EPA-R3-72-004
. 10-,0 Ecological Research Series
August 1972
The Role of Sludge Worms
in Eutrophication
Office of Research and Monitoring
U.S. Environmental Protection Agency
Washington, D.C. 20460
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and
Monitoring, Environmental Protection Agency, have
been grouped into five series. These five broad
categories were established to facilitate further
development and application of environmental
technology. Elimination of traditional grouping
was consciously planned to foster technology
transfer and a maximum interface in related
fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
U. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ECOLOGICAL
RESEARCH series. This series describes research
on the effects of pollution on humans, plant and
animal species, and materials. Problems are
assessed for their long- and short-term
influences. Investigations include formation,
transport* and pathway studies to determine the
fate of pollutants and their effects. This work
provides the technical basis for setting standards
to minimize undesirable changes in living
organisms in the aquatic, terrestrial and
atmospheric environments.
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EPA-R3-72-00^
August 1972
THE ROLE OF SLUDGE WORMS IN EUTROPHICATTON
By
Ralph 0. Brinkhurst
Project 16010 ECQ
Project Officer
Charles F. Powers
Environmental Protection Agency
National Environmental Research Center
200 S.W. 35th Street
Corvallis, Oregon 97330
Prepared for
OFFICE OF RESEARCH AND MONITORING
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, B.C. 20k60
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EPA Reviev Notice
This report has been reviewed "by the Environmental
Protection Agency and approved for publication.
Approval does not signify that the contents
necessarily reflect the views and policies of
the Environmental Protection Agency, nor does
mention of trade names or commercial products
constitute endorsement or recommendation for use.
11
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ABSTRACT
In grossly polluted Toronto Harbour, Lake Ontario the worm popula-
tion averaging 96,000 animals/m2 (l8.3 g ash-free dry wt/m2)
assimilates 1,7^3 kcals/m2/yr and produces 1550 kcals/m2/yr worm
tissue. Of the total nitrogen input of 830 tons/year, 7 tons is
present in worm tissue at any one time and 113 tons may be
circulated in a year. Production and Respiration values for tubi-
ficids should be based on mixed species cultures because of
positive interactions between species which increase the assimi-
lation rate and assimilation efficiency. Worms feed selectively
upon the bacteria in sediment. They also pump water through
sediment. Large worm populations play a significant role in
preventing organic matter from being deposited in an energy or
material sink. The quality or specific identity of organic
matter inputs are of as much interest as their total calorific
or carbon content in determining their effect on benthic produc-
tion.
This report was submitted in fulfillment of 16010 ECQ under the
partial sponsorship of the Office of Research and Monitoring,
Environmental Protection Agency.
111
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CONTENTS
Section Page No.
I CONCLUSIONS 1
II RECOMMENDATIONS 3
III INTRODUCTION 5
IV MATERIALS AND METHODS 9
V TORONTO HARBOUR STUDIES 19
VI PRODUCTION STUDIES 35
VII DISCUSSION 57
VIII ACKNOWLEDGEMENTS 59
IX REFERENCES 6l
X PUBLICATIONS 63
XI APPENDIX 65
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v
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FIGURES
Figure Page No.
1.
2.
3.
k.
5.
6.
T.
8.
9.
10.
11.
12.
13.
Ik.
15-
16.
Common view of material and energy pathways
Potential sources of return from sediment
Site location and sampling grid
Apparatus for collecting faeces
Abundance of tubificids
Abundance of T. tuMfex
Abundance of L. hoffmeisteri
Abundance of P. multisetosus
Abundance of L. udekemianus
Abundance of A. pluriseta and P. vejdovskyi
Seasonal abundance of three worm species
Seasonal changes in biomass of three worm species
Supposed seasonal changes in mean weight
Defecation rate of worms at mean temperature of 3.7°C
Defecation rate of worms at mean temperature of 3.5°C
Possible changes in defecation rate with temperature
7
7
10
16
20
21
22
23
2>J
25
30
31
32
U7
U8
50
VI
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TABLES
Table Page No.
1. - Overall abundance of tubificid species in
Toronto Harbour 26
2. Distribution and abundance of the 3 most abundant
tubificids for each of the h zones identified in Fig.l 27
3. Vertical distribution of worms in sediment during
one diurnal period 28
k. Average dry weight of worms in most polluted and
least polluted parts of Toronto Harbour 33
5. Rates of oxygen consumption for 3 tubificid species
at h temperatures 36
6. Rates of oxygen consumption for 3 tubificid species
at h temperatures in pure and mixed culture 37
7. Rate of oxygen consumption of 3 tubificid species
at 2 population densities 39
8. Gain in weight of cultures of 3 tubificid species
under various conditions Uo
9- Gain in weight of pairs of tubificid species and of
a mixture of all 3 after 6 months Ul
10. The nitrogen, organic matter and calorific content
of faeces of 2 tubificid species at k temperatures h3
11. The % organic matter and % nitrogen content of 3 types
of sediment and of the faeces of 2 tubificid species
fed with them 45
VI1
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12. The % organic matter in faeces of a mixed culture
of 3 worm species compared to the content of faeces
of the same worms in pure culture and to the original
mud U6
13. Defecation rates for tubificid worms fed on mud 51
ll*. Defecation rates for tubificid worms fed on 3
different sediments 52
15. Standing stock, annual production and assimilation
"by oligochaetes at U stations in the Bay of Quinte
and Toronto Harbour 5^
Vlll
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SECTION I
CONCLUSIONS
1. Production and assimilation estimates of "benthic organisms
made by reference to the Ivlev formula Ingestion =
Production + Respiration + Egestion + Excretion should be
made on species mixtures as found in nature because of
interspecific interactions.
2. The quality of sedimented material is important in determining
material and energy sources available to the benthos via the
microbiota as some material is relatively refractile while
some is highly labile.
3. At densities as high as 18.3 g ash-free dry weight of worms/
m2 (96,000 worms/m2) assimilation may reach 1,7^3 kcals/m2/yr
production 1,550 kcals/m2/yr.
h. Assuming that the input of N2 of 830 tons/annum is evenly
mixed throughout Toronto Harbour, the standing stock of worms
represents 7 tons, the throughput represents 113 tons. As
the available nitrogen enters at one point in the system
where dredging is frequently performed, this represents a
considerable fraction of the allochthonous nitrogen.
5. Without estimations of predation on worm populations it is
impossible to state how much of the worm production is
returned to the ecosystem and how much is being recycled
within the worm - microbiota - sediment complex.
6. Worm populations exert a strong selective influence on the
bacterial populations upon which they feed.
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SECTION II
RECOMMENDATIONS
The activity of the benthos in retrieving materials and energy
from the sedimentary "sink" in aquatic ecosystems should be
assessed in any study of productivity or eutrophication of
lakes. The secondary production of worm tissue may reach
significant proportions and hence may complement their
activities in physical stirring and irrigation of sediment.
The activities of benthic animals play a significant role in
determining the nature and quantity of bacterial populations
in sediment, so that the type and amount of benthos present
should be noted in bacteriological surveys of aquatic systems
as well as the normal abiotic factors.
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SECTION III
INTRODUCTION
In the study of eutrophication we are concerned with the circulation
of materials and the flow of energy through aquatic systems. While
questions of quality, such as an overabundance of particular algae
(Cladophora) or certain less desirable fish species (Carp), are of
importance, they have attracted less attention than questions of
quantity of materials and energy which should be susceptible to
analysis.
Materials and energy sedimented out to the bottom may be thought of
as descending to a "sink" from which return is difficult. Re-sus-
pension of sediment has been long suspected but rarely demonstrated.
Chemical diffusion processes at the mud/water interface have
received some attention, but the activities of benthic organisms
have not often been thought of in terms of regeneration of material
and energy from that sink. The irrigation of sediments by worms
may be substantial, and will be investigated in the future. In
this study we attempted to measure the potential of a worm popula-
tion as a means of retrieving material and energy from the sink.
When organic matter from primary production (autochthonous) and
from external (allochthonous) sources reach the sediments of a
lake they are decomposed by bacteria, which themselves form an
important component of the diet of many benthic animals (Wavre and
Brinkhurst, 1971)• This decomposition creates an oxygen demand
(the respiration of microbiota and benthic animals plus chemical
oxygen demand of allochthonous materials) and this, together with
the clogging action of settling and resettling sediment, limits
the diversity of the benthic fauna. The distribution and abun-
dance of benthic animals is the best method of detecting the
nature, extent and source of pollution in aquatic ecosystems (Hynes,
I960; Brinkhurst, 19^9) but beyond this we need to understand the
function of benthic organisms in polluted sediments.
Organic additives, nutrients, or heated effluents may increase
production in aquatic systems, despite the natural tendency to
deposit nutrients in the sediment or to lose them over the outlet.
According to widely held beliefs (largely unsubstantiated and based
on a largely discredited lake typology system) any quantum addition
of organic matter to a lake will "age" it by remaining in circula-
tion. Significant release of phosphates from anaerobic sediments
is accepted, so.that an eutrophic lake should release nutrients to
the water column in late summer and under ice-cover. This is
Preceding page is blank
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presumed to be available for algal growth in the spring by being
stored in algal cells during the periods of complete aeration
during ice-free cold periods.
Return from the sediment may occur not only by simple chemical
exchange, but by the irrigation of sediment by organisms, parti-
cularly worms, and also by the build up of tissue by larger
organisms that may migrate into or through the water column or
be consumed by migratory organisms such as fish.
If sediments are irrigated by worms , the surface may be aerobic
but the faeces are derived from the anaerobic layer, so that their
deposition on the surface may release nutrients into the water
column. So may the water flow drawn through the sediments (provi-
sionally estimated as better than 600 ml/m2/hr by Wood and
Brinkhurst, In Mss.). This problem will be the next to receive
our attention, but first we attempted to assess the production of
worm tissue in Toronto Harbour and in the trophic gradient of the
Bay of Quinte (which strongly resembles the whole Lake Erie system
of three basins).
To do this we had to study:
Identity of worm species , their distribution and abundance in the
habitats, their standing stocks through time, growth and reproduc-
tion (production), respiration, egestion, egestion rate, sediments
and sedimentation rate, temperature and oxygen characteristics of
the environment. Initial studies on the use of selected components
of the potential food supply by specific worms have also been
attempted, as have studies of flux rates of specific amino acids
and sugars between mud, water, microflora and worm populations.
The primary aim of this study was to evaluate THE RECOVERY OF
POTENTIAL NUTRIENTS FROM SEDIMENT VIA THE PRODUCTION OF SLUDGE
WORM TISSUE and THE RATE OF DESTRUCTION OF ORGANIC MATTER IN
SEDIMENT VIA ASSIMILATION BY WORMS (PRODUCTION PLUS RESPIRATION).
The aim is clarified in Figs.1-2.
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E (sun)
nutrients
Fig.1. Common view of nutrient pathways.
Fig. 2. Potential sources of return from sediment.
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SECTION IV
MATERIALS AND METHODS
Toronto Harbour has a surface area of 373 ha and a maximum depth of
12.5 m. The Don River enters the northeast corner of the harbour
via the Keating Channel. The harbour is connected to Lake Ontario
via two narrow channels (marked by arrows in Fig.3) known simply
as the East and the West gaps. The northern and eastern sides are
embanked and are used as docks, and the banks are covered with
warehouses and industries. The south and west shores are formed
by the Toronto islands, between which run a series of lagoons and
channels. The islands are mostly used as parkland, with a few
residents still occupying the southeast corner. A number of
sailing clubs and a small airport form part of the recreational
facilities.
The two major sewage works on the Toronto waterfront discharge
their effluents on either side of the harbour in Ashridges Bay and
Humber Bay. Storm sewers discharge into the harbour along the
northern wall, and the Don River carries a heavy load of organic
and industrial wastes.
The survey of worms in Toronto Harbour was carried out during May-
July 1969, the sampling stations being based on a grid plan. Four
samples were taken at each of the 1*3 stations with a KB corer (5
cm diameter) described elsewhere {Brinkhurst et al., 1969). Samples
were screened through narrow mesh screens (0.2 mm opening) and worms
were picked using stereo microscopes. Two of the samples were used
to determine the dry weight of worms (plus gut content) at each
station. Eight of these samples were used to determine the average
dry weight of a worm. This value was used to convert dry weight
values to standing stocks estimates. The other two samples were
used to determine the identity and abundance of each species
present. Average values of dry weight for worms minus gut contents
for each species were used to obtain calculated dry weight estimates.
Some additional data from continuous studies at Hanlan's Point are
used in addition to the survey data.
Standing stock data were derived from four core samples collected
each month from Hanlan's Point, Toronto Harbour. Samples were sieved
using 0.2 mm pore size screens and the worms were identified using
a stereo microscope. Worms were held in dechlorinated city tap water
at 10"C for 12 hours to allow the guts to clear before being washed
and dried in preweighed planchets at TO°C for 12 hours. The planchets
were cooled in a dessicator and reweighed on a Cahn electrobalance.
Preceding page is blank
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76- 78'
OO' 30' 00'
n I i n 11 i 11 11: irn rTTTrrrrm »•
Fig. ?. Samrling stations in Toronto Harbour, survey dated May-July, 1969.
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Sediment analyses were made on samples dried at 60*C prior to
analysis. Percentage organic matter was determined by igniting
samples in preweighed crucibles at 500°C for 1 hour. The cool
dry crucibles were then reweighed. Caloric content was determined
by wet oxidation by the method described by Hughes (1969). Attempts
at microbomb determination of caloric content were abandoned after
trying several ways of combining the mud with oil or placing it in
paper cups to obtain complete combustion. Nitrogen content was
determined by a semi-micro Kjeldahl technique based in methods
described by Jackson (1958), the American Instrument Co. (1959),
and the Association of Official Agricultural Chemists (1965).
Material of known weight (100-300 mg) was kept in a 100 ml flask
to which was added 6 ml 36W f^SO^ containing 0.3 g salicylic acid.
Samples were held overnight, and then digested with about 0.75 g
Na2S203.5H20 slowly heated for 5 minutes. The heat was turned off
and 0.5 g red HgO, 2.0 g ^SO^ and 2 glass beads were added. The
flasks were gently reheated until frothing ceased, when the tem-
perature was slowly raised and digestion completed. Steam disti-
llation was carried out after adding 15 ml 50% NaOH containing
5% Na2S203.5H20. Titration was performed with 0.005 N HC1.
Temperature and oxygen values were obtained with a Mackereth Oxygen
Probe (Lakes Instruments Co. Ambleside, Westmorland).
Worms used in respiration studies were also obtained from Hanlan's
Point, Toronto Harbour, where the water is U-5 m deep. Samples were
taken with an Ekman grab and sieved in the field in a wash bucket
with an 0.5 mm pore size, thus eliminating the smallest worms. The
residue was placed in a bucket with some lake water, and a number
of such buckets were returned to the laboratory, where they were
stored in environmental rooms at 5°C, 10°C, 15°C, and 20°C for at
least 3 weeks prior to use. Worms were then sorted with pasteur
pipettes from sub-samples sieved through fine screens (0.25 mm pore
size) and were identified under a stereo microscope. One hundred
and fifty worms of each species were identified, placed in a tube
with some sediment and water, and returned to the environmental room
for 12 hours. The density used (l08,000/m2) was equivalent to that
at the sampling site.
The average dry weight of T. tubifex and L. hoffmeisteri used in these
studies was high (about 0.1* mg per worm as opposed to 0.06 and 0.2 mg
respectively for field populations). All available specimens of the
scarcer P. multisetosus were used so that their average dry weight
(0.1 mg) was the same as that derived from field populations. Age
of worms cannot be established.
11
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The worms were washed in dechlorinated tap water "before "being
introduced into glass vessels containing about 20 ml washed sand
(0.25 mm particle size) and 120 ml water, and these respiratory
chambers were closed by inserting YSI 5^20A self-stirring BOD
probes into the neck. The probes were cleaned frequently and the
membranes were replaced at least once a week. In each experiment
H such chambers were prepared, one without worms being used as
a control.
Prior to the introduction of the worms, the chambers were placed in
a beaker full of dechlorinated tap water covered with foil, and
sterilized in an autoclave for 15 minutes. After cooling, the
vessels were placed in a constant temperature bath at the experi-
mental temperature, and aerators were introduced for a minimum of
12 hours to ensure that the oxygen saturation remained above 85$.
The vessels were eventually placed in an enclosed water bath
connected to a Haake constant temperature circulator. A BOD probe
was introduced into the neck of each chamber and the system was
allowed to stabilize for 2 hours prior to the introduction of the
worms. A small piece of stramin was placed over the sand after the
worms had burrowed into it, and this was held down by a number of
glass beads. This was to prevent the stirrer from agitating the
sand too violently. The worms protruded their posterior ends
through the stramin into the water in the normal manner. An
initial reading on the YSI dissolved oxygen water was taken 10
minutes after the worms were introduced, and then again after 2
hours. The control values were subtracted from the gross respi-
ration data to obtain net respiration values. Short-term experi-
ments were used in order to eliminate problems due to recolonization
of sterile sediment by bacteria from the worm faeces. Continuous
records were not kept because of the problem of continually agitating
the worms - every precaution being used to keep conditions as natural
as possible.
The main series of experiments was carried out using 150 worms of a
single species in each respiratory chamber, the fourth chamber
lacking worms being used as a control. Once oxygen levels had been
determined (after 10 minutes and 2 hours) the worms were retrieved
and held overnight in sieved mud. The same individuals were then
used again the next day in the second half of each experiment, this
time equal numbers of each of the three species being mixed together
and introduced into each chamber.
At the end of each run, the mixed worms were re-identified. The
worms of each species from each respiratory chamber were placed in
separate test tubes in water and were held overnight at 10°C to allow
12
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the gut content to be voided. They were then dried on planchets at
70°C for 12 hours and weighed on a Cahn electrobalance. The dry
weights obtained could then be summed a) according to species in
order to determine the rates of oxygen utilization in pure culture
and b) according to respiratory chamber occupied by a mixture of
all three species in the second half of each experiment.
Each run (separate then mixed cultures) was repeated 3 times at
each temperature used (5°C, 10°C, 15°C, and 20°C). Hence, at the
end of this series of experiments 3 determinations of oxygen up-
take by each of 3 species and 9 determinations of each mixed cul-
ture had been obtained at each of U temperatures. Each determina-
tion is, however, an average rate for the duration of the experi-
ment .
The results were calculated as follows. In order to compare the
respiratory rates of one species with another, the rate determina-
tions from each of the 3 experimental runs at a given temperature
were simply averaged. The respiratory rates of mixed cultures were
obtained in a slightly different manner, because there are 3
replicates of this arrangement in each experimental run. The total
volume of oxygen used in all three chambers of a run was divided by
the total weight of worms to obtain an overall value for respira-
tory rate. An average of the 3 determinations at each temperature
was then calculated. This was then compared with a value for the
respiratory rate of worms held in pure culture derived as follows.
The total oxygen consumption in all 3 bottles (one containing
T. tubifex, one with L. hoffmeisteri and the third with P. multi-
setosus)was divided by the total weight of worms used in the
experiment (the same weight used to calculate the respiration rate
of mixed cultures in the same run). The 3 values were then
averaged. This procedure is described in detail as it is possible
to average the values in other ways. Examination of the tabulated
results should further clarify the procedure adopted.
As the results obtained by mixing the worms could be attributed to
the degree of handling or starvation, the process was repeated at
10°C but the respiratory rate of mixed cultures was determined
before that of the pure cultures. Once again the experiment was
repeated 3 times, yielding 9 values for mixed cultures, and 3
values for each of the 3 species isolated in pure culture.
By mixing 50 specimens of 3 species in a single chamber, the actual
population density of any one species per chamber has been reduced
to 1/3 of its density in pure culture despite the fact that the
13
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population density of all worms remained at 150 per chamber. The
possible effect of this was determined by comparing the respira-
tory rate for each species at densities of 150 and 50 per chamber,
again at 10°C and with 3 replicates.
Worms used for growth studies were also collected from Hanlan's
Point. Starved worms were wet-weighed on a Cahn electrobalance
in a fully saturated atmosphere prior to and at the conclusion of
each experiment. Dry weight was taken to be 1.6% of wet weight
(Brinkhurst, 1970).
Cultures were maintained for 6 months because growth studies based
on cultures maintained for between 9 and 20 days proved unsatisfac-
tory because of weight losses or slight weight gains rather like
those demonstrated by Appleby and Brinkhurst (1970).
The worms were maintained in pure culture and also in every
possible combination of pairs as well as mixtures of all 3 species.
In pure culture 18 worms per vessel were used, 9 of each species
were used in paired situations, 6 of each species where all 3
were present, densities far short of those found in Toronto Harbour.
The sediment used was autoclaved for 20 minutes at 110*0 and 20 psi
to eliminate small worms and cocoons that would pass through fine
screens. After cooling, the sediment was inoculated with an 18 hr
stock culture of bacteria in nutrient broth. The culture contained
5 of the forms found in Toronto Harbour (Wavre and Brinkhurst, 1971)
i.e. Flavobacterium sp. Bacillus cereus, B. mycoides, Pseudomonas
flucrescens and a Micrococcus sp. The sediment once inoculated was
held for kQ hr at 20 C prior to the introduction of the worms. About
UOO ml of wet mud was placed in each 600 ml plastic box into which
18 worms were then introduced. The boxes were placed in wooden
containers at random, and dechlorinated city water (from Lake Ontario)
was allowed to flow through the system continuously, the water level
being maintained at twice the height of the plastic boxes. Temperature
records were kept daily, and were roughly comparable with the field
temperatures (mean temperature 10.9°C in the laboratory, 9-7°C for
the same period in the field in 1969 and 1970). A total of 5 repli-
cates of each combination was used, and as there are 7 combinations
possible, a total of 35 plastic boxes was used. At the end of 6
months (July 12, 1970 to January, 1971) the worms were retrieved by
washing the mud through a 0.25 mm screen. They were identified,
counted, dried, and weighed.
Analysis of variance was performed using the method described by
Snedecor and Cochran (1968).
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The collection of faeces was made using the Alsterberg inverted-
culture technique in which worms are placed in sediment in small
vials which are then covered with burlap (Fig.li). Once the
worms protrude through the fabric, the vial may be inverted over
a collecting vessel into which faeces fall (Appleby and Brinkhurst,
1970).
Worms were weighed with the guts empty prior to each experiment
using a Cahn electrobalance, and 3 samples of worms were used to
determine wet weight/dry weight ratios at the beginning of each
experiment. These values were used to determine the dry weights
of worms used in each vial. Unless otherwise stated the mud used
in the vials was sieved through a Wo.60 screen (250 M pore size)
and allow to settle overnight. Once in the partially filled vials,
the worms were covered with a little of the silt and a layer of
wet cotton was added, followed by a piece of stramin. The vials
were kept upright for two days, and then inverted for two days
before faecal samples were taken. The faeces were collected on
preweighed planchets in glass chambers (60 x 35 mm), the collecting
funnels penetrating neoprene stoppers that isolated the collecting
chambers from the surrounding aquarium tank. The chambers were
filled with 50 ml distilled water, to which was added 300 mg NaCl.
Once this had dissolved, 0.3 ml of an iodine solution was introduced
slowly, just above the planchet, so that a discrete layer formed
below the salt solution. The salt and iodine removed from the
stem of the collecting funnel, and the system was topped up with
distilled water. These precautions were taken to minimize the
development of bacteria on the faeces.
One such set-up was placed beneath each experiment vial for hQ hours
at a time. After the first time period the faeces were weighed
and used for the determination of % organic matter. After the
second interval the fresh faeces were used to obtain nitrogen
content, the third set being used for calorific values. The same
sequence of samples was taken a second time with the same set of
experimental vials, sometimes more often. Sometimes samples had
to be pooled to obtain sufficient material for analysis. Control
vials full of sediment were kept in the aquaria along with the
experimental chambers at all times in order to determine changes
in the parameters measured brought about by the microflora alone.
An initial experiment was run at 5°C and a subsequent experiment
was run at 10°C, 15°C and 20°C using one stock of sediment which
was made up separately to that used at 5°C. In addition to the
effect of temperature, preliminary assessment of the effect of
particle size was made at 5°C alone, using mud passed through No.6o,
15
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Vial
Clamp
Water
Sediment
Rubber Band
Cotton Wool
Stramin
Worms
Watchglass
Funnel
Funnel Holder
Beaker
Faecal Pellets
Planchet
Fig. h. Apparatus for collecting faeces. The whole assemblage is
kept in an aquarium.
16
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120, and 230 screens (250, 120 and 63 y respectively).
In a final series, run at 10°C for 2h and U8 hours, defecation rates
were determined for fifteen worms of each species in pure culture,
and a total of fifteen mixed worms (five of each species).
Calorific values of the three species of worms were determined by
igniting 5 large samples of worms of each species in Phillipson
microbomb (Gentry Wiegert) calorimeter. An oxycaloric coefficient
of U.825 kcal/1 Q£ was used to convert respiration data (Brody,
19^5). The worms were held in dechlorinated tap water overnight
before being dried at 70°C for 20 hours.
A pellet press was used to compact the worm tissue. Five replicates
were obtained. Ash-free dry weights were determined by ignition at
500"c for 20 minutes. The ash content of worms was found to-be 8.55
9-7 and 23.6$ for T. tubifex, L. hoffmeisteri and P. multisetosus.
17
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SECTION V
TORONTO HARBOUR STUDIES
The study area consists of a busy commercial harbour on the St.
Lawrence Great Lakes at Toronto, Ontario (Canada). The seaport
is enclosed by a chain of islands and sand bars used as a. park and
an airport with a few residents at the southeast end. The
location is illustrated in Fig.3.
Some of the environmental variables were described by Bennett (1970),
Brydges (1970) and Michalski (1970). Temperature and oxygen records
are presented in Appendix 1, data on nitrogen and percent organic
matter of sediments in Appendix 2.
The maximum depth of the harbour is 12.5 m (Ul ft) the surface area
approximately 373 ha (920 acres). The Don River enters at the north
east corner, bringing with it a considerable amount of domestic and
industrial waste. Wastes also enter the harbour from the storm sewer
outfalls along the northern wall. The ships in the harbour and the
residents plus the huge transient population of day trippers in
summer add to the pollution of the environment. Toronto's major
sewer outfalls lie outside the harbour proper and are unlikely to
affect conditions within it. Coliform values north of the line A-A Fig.3
were greater than 2^00/100 ml, below it in excess of 1000/100 ml
(x 2220) in December 1967 (O.W.R.C. data).
The distribution and abundance of sludge worms (Tubificidae) has been
described by Brinkhurst (1970). The data presented here are in the
form of maps indicating generalized zones (Figs.5-10). Most
tubificids are found in the northeast and northwest corners, least
in the island lagoon area. The commonest species are Tubifex tubifex,
Limnodrilus hoffmeisteri and Peloscolex multisetosus (Table l) but
there is a gradual change from this pollution tolerant complex at
the mouth of the Don River, to a mixture of eutrophic lake species
in Zone IV, where Aulodrilus and Potamothrix species are found. Data
on the distribution of the three commonest species are presented in
Table 2. The totals derived from counting identified worms' from
paired samples are very close to those calculated from dry weights of
all worms in the second set of paired samples from the same station.
Samples taken at one point during the period 2 a.m. to 10 p.m. on a
single day revealed no diurnal changes in depth - distribution of
worms in the sediment (Table 3). The single period" that seems to
suggest diurnal changes (2 p.m. values) is that when most samples have been
taken over extended periods, when the vertical distribution pattern
is similar to that shown in the rest of Table 3 (Bj-inkhurst et/al. 1969).
19
-------
T O R O N T
rv
TORONTO
ISLAND AIRPORT
SCAU Of MiTIRS
500
' J
Fig. 5. Abundance (no./m ) of tubificids in Toronto Harbour. Zone 1 (solid), >125,000; zone 2,
75,000-125,000; zone 3, 25,000-75,000; zone it, >25,000.
-------
TORONTO
TORONTO
ISLAND AIRPORT
SC»Li Of MtTERS
500
1
L
Fig. 6. Abundance of Tubifex tubifex in Toronto Harbour as percentage of all tubificids. Zone 1
(solid), >50$; zone 2, 25-50$; zone 3,
-------
T O R O N T
•-
1
TORONTO
ISLAND AIRPORT
SCALI Of MITSIIS
500
Fig. T. Abundance of Limnodrilus hoffmeisteri in Toronto Harbour as percentage of all tubificids
Zone 1 (solid), >50$; zone 2, 25-50$, zone 3,
-------
TORONTO
-
TORONTO
ISLAND AIRPORT
Fig. 8. Abundance of Peloscolex multisetosus in Toronto Harbour as percentage of all tubificids,
Zone 1, >25%; zone 2,
-------
TORONTO
.
SC«tl 01 KIIIKS
Fig. 9. Abundance (no./m ) of Limnodrilus udekemianus in Toronto Harbour. Zone 1 (solid), >5QOO
(mean, 9500); zone 2, 1000-5000 (mean, 2500); zone 3, 0-500 (mean, 360).
-------
TORONTO
^
SC»Li Of METERS
0 500
•J
Fig. 10. Abundance (no./m } of Aulodrilus pluriseta and Potamothrix vejdovskyi in Toronto Harbour.
A. pluriseta: zone 1 (solid), 9250; zone 2, 750-3750 (mean, 2000); zone 3, 250-750 (mean, 350);
zone 4, absent. P. vejdovskyi: zones 1 and 2 present (mean, 800); zones 3 and k, absent.
-------
- abundance of tubificid species in Toronto Harbour.
o\
Number Tubifex Linmodrilus Peloscolex Other Total
tubifex hoffmeisteri multisetosus species
p
( thousands /m ) 39 26 13
31 15 7 100
-------
Table 2. Data on the distribution and abundance of the three most abundant tubificids
2 2
(average number/m , percent, and dry weight in g/m ) for each of the four zones
identified in Fig.l, and for Hanlan's Point, Toronto Harbour.
L = Limnodrilus hoffmeisteri; P = Peloscolex multisetos_us_.
T = Tubifex tubifex;
Zone
No. stations
2
Avg no./m
(thousands )
Avg no./m
(thousands)
calculated from
dry weight plus
gut content
%
Avg dry weight
(g/m2)
calculated for
worms minus gut
1
8
T 115
L 58
P 2U
£ 197
I, 19U
T 58
L 30
P 12
T 22.9
L 17-5
P 2.3
I U2.7
2
11
55
33
16
10U
106
53
31
16
11.0
9.8
1.6
22.1*
3
22
18
21
12
51
59
36
Itl
23
3.7
6.3
1.1
11.1
1;
2
3
8
12
23
19
lU
33
52
0.7
2.k
1.2
U.3
Hanlan's Point
1
12
16
2
30
UO
53
7
2.U
fc.9.
0.2
7.5
content
Avg dry weight
(g/m2) of worms
plus gut contents
(all species)
98.5
U8.0
26.5
9.0
Ratio dry weight
plus gut content/
dry weight without
gut content
2.3:1
2.1:1
2.1:1
-------
Table 3. Vertical distribution of worms in sediment during one diurnal period.
Numbers are given per core sample; numbers per square meter are approximately
500 times greater.
ro
CO
Depth in
(cm)
0-2
2-U
li-6
6-8
8-10
10-12
core
2 AM
1*7
Hi
7
2
0
12
Time
6 AM
91
Uo
21
6
k
2
10 AM
56
28
9
7
U
0
2 PM
10
111
11
U
l
2
6 PM
60
36
11
2
5
1
10 PM
111
33
12
U
2
5
-------
The distribution and abundance of tubificid species in Toronto
Harbour clearly demonstrates the polluting effect of the Don River,
which is still subject to intense stress despite considerable
improvement over the last few years. This fact is reinforced by
a consideration of the rest of the fauna. Over nearly all of the open
harbour and in the docks themselves the tubificids are the entire
fauna. Among the island lagoons Sphaerium, Pisidium, Valvata,
Chironomus , Orconectes , Asellua» Gammarus , Caenis, Trichorythodes ,
Ischneura, Chromagrion, Glossiphonia, Helobdella and a number of
other genera were found in small numbers.(Operation Sludgeworm -
Opportunities for Youth 1971 - Final Report).
The detailed distribution of tubificid species confirms earlier
reports of the relationship between sludge worms and pollution
documented elsewhere (Brinkhurst and Jamieson, 1971).
Both numbers and weights of worms varied through quite wide limits
in 1970, although the plots of the logs of values obtained demons-
trate no seasonal trends (Figs.11-12). An attempt to demonstrate
breeding periods by reference to mean weights failed, and the
supposed upward trends in mean weight revealed during 1970
13) were regarded as spurious despite the statistically significant
differences in slopes of the lines as subsequent data failed to
conform to this pattern. Steady changes of slope like this with
time could relate to long-term changes in conditions in the
locality, in which case a similar trend from Zone I to Zone IV of
Toronto Harbour (Fig.5) might be demonstrable. The results of
such a test are reproduced in Table k, and give little credence
to the idea.
Tubificid worms do not all reproduce at a given time for a given species ,
or at a fixed time in any one habitat. Reproduction may occur very
rapidly after intermittent pollution stress, but no discrete cohorts
may be detected, and the life-span of a worm in the field is difficult
to determine. Worms may live two years, breeding mostly in their
second year (Brinkhurst and Jamieson, 1971) but in polluted localities,
such as Toronto Harbour, life histories are very difficult to establish.
While worms may reach a peak biomass in August with a minimum in
December, numbers appear maximal in March and September, but these
could be sampling artifacts only to be overcome by intensive sampling
programmes beyond our resources. For studies on production we will
assume constant standing stocks equal to the means derived from the
1970 data.
29
-------
3-0-
o
•
o
V)
E
2-0-
c
c
1-0-
0-1
• •
~T~ ~T- — ?— — T—
D69 J?o F M
— i
M
J
1
A
r
S
•-P
O N D70 J71
MON TH
Fir;. 11. Seasonal abundance of three worm species.
-------
-
2-2-
1-9-
i
T-
o
O)
E
o
$ 1-3
*O
ti to
0-7-
0-4-
O)
O
0-1
D69 J70 F M A M J J A S O N D70 J71
MONTH
ig. 12. Seasonal changes in biomass of three worn species,
-------
u
'
0)
E
.E
E
«•
0
^
IX
0-24-
0-22-
0-20-
0-18-
0-16-
0-14-
0-12-
010-
OO8-
0-06-
0-04-
0-02-
0
o ,-l
o _ «, **
_ .. — -"""
— — •* "**
f ^~~~~
,^**""p' °
o .-°-~~~- *
^ — — •""* °
00 • • •
A
I I
i r
D69 J?o F M A M J J A S O N D70 J?1
MONTH
Fir. 13. Supposed seasonal changes in mean weiglit of worms.
-------
Table U. Average dry weight in mg per worm at the most polluted (Zone l)
and least polluted (Zone U) parts of Toronto Harbour, July 1971.
U)
Tubifex
tubifex
Limnodrilus
hoffmeisteri
Peloscolex
multisetosus
Zone 1
0.209
0.093
Zone
0,100
0.208
-------
SECTION VI
PRODUCTION STUDIES
As individual worms cannot be aged, and there are no clear cohorts
in the population structure of worms, production studies have to
be based on the method derived by Ivlev (1939). In this approach
laboratory studies of ingestion, growth, respiration, egestion,
excretion and secretion are carried out in order to balance the
equation:
Ingestion = Production + Respiration + Egestion + Excretion +
Secretion
It is usually difficult to obtain ingestion values, so that growth
(including reproduction) respiration and solid egestion are
measured in calorific terms and the formula is solved for ingestion
assuming that fluid excreta and secretions are trivial. Most of
the assumptions have not been fully tested until recently (Hargrave,
1971). In our study we attempted to evaluate each parameter
(other than secretions and fluid excreta) for three species reared
in isolation and in mixed cultures.
Respiration
The rate of oxygen consumption in yl/mg dry weight/hr of the 3 species
when measured alone varies in relation to temperature as demonstrated
in Table 5. A two-way analysis of variance demonstrated significant
differences due to temperature (F = 11.02 on 3 and 2k d.f., P<0.0l).
As there were significant differences between species (F = U.85 on
2 and 2k d.f.) a one-way analysis was performed in order to determine
which differences between species were significant. This showed
a significant difference between P. multisetosus and L. hoffmeisteri
at the 5$ level, but none between P. multisetosus and T. tubifex
or L. hoffmeisteri and T. tubifex.
The data for separate species compared to that from subsequently
mixed worm cultures again varied with temperature, of course, but
the data from mixed cultures differed from those obtained from
pure culture (Table 6). A two-way analysis of variance indicated a
significant effect of temperature (F = 37.18 on 3 and 16 d.f.,
P<0.01) and also a significant difference between separate and
mixed cultures (F = 1^.77 on 1 and 16 d.f., P<0.0l). The inter-
action of temperature vs separate or mixed cultures was not significant.
A Duncan multiple range test (Steel and Torrie, I960) applied to
the interactions between temperatures for both separate and mixed
cultures demonstrated a significant difference (P<0.0l) between results
obtained at 20 *C and those at all other temperatures in both separate
and mixed cultures. A significant distinction could be made (P<0.05)
35
-------
Table 5. Rates of oxygen consumption in jil/mg dry weight/hr for 3 tubificid species at
1* temperatures (T = T. tubifex. L » L. hofftaeisteri. P = P. multisetosus).
U)
o\
Total
Temperature Expt
No
5C 1
2
3
IOC 1
2
3
15C 1
2
3
20C 1
2
3
T
1*7.
81.
71.
39.
51.
77.
1*1.
61.
66.
55.
55.
65.
2
1
1*
2
1
1
6
7
U
U
3
5
dry weight
(mg)
L
72.9
68.3
75.5
63.0
71.3
66.2
1*7.1
76.9
55.8
52.9
60.7
51.9
P
22.2
16.7
13.1*
18.2
18.7
19.6
15. »»
16.9
15.2
19.2
ll*.9
12.6
Oxygen consumed
(>H/hr)
T
11*. 7
15.1
15.8
11.2
08.1*
ll*. 7
18.2
21*. 5
23.5
23.5
31.5
35-0
L
12.3
13.7
13.0
ll».0
13.3
lU.O
16.8
17.5
18.9
19.2
29.1
30.5
P
07.7
03.5
08.1
08.1
03.5
08.1
07.0
01*. 6
08.1
13.0
05.3
08.8
Respiration rate
(;il/mg/hr)
T
0.
0.
0.
x 0.
0.
0.
0.
x 0.
0.
0.
0.
x 0.
0.
0.
0.
x 0.
31
19
22
2U
29
17
19
21
1*1*
1*0
35
1*0
1*2
57
51*
51
L
0.17
0.20
0.17
0.18
0.22
0.19
0.21
0.21
0.36
0.23
0.3l*
0.31
0.36
0.1*8
0.59
0.1*8
P
0.35
0.21
0.60
0.39
0.1*1*
0.19
O.Ul
0.35
0.1*5
0.27
0.53
0.1*2
0.67
0.35
0.70
0.56
-------
Table 6. Rates of oxygen consumption in pl/mg/hr for 3 tubificid species at 1* temperatures determined in pure
culture and mixed culture (see text for details of computing data from pure cultures).
Temperature Expt
No
uu 5C 1
— i
2
3
IOC 1
2
3
15C 1
2
3
20C 1
2
3
Total
dry weight
(mg)
1*2.2
166.1
160.3
120.5
lfcl.1
162.9
10U.1
155. !»
139.2
127-5
130.8
129.9
2 oxygen used
by 3 species
in pure culture
Cul/hr)
3U.7
32.2
36.8
33.3
25.2
36.8
142.0
1*6.6
50. U
55.7
65.8
7U.2
2 oxygen used
in mixed culture
of 3 species
fyil/hr)
22. U
12.0
22.8
21.0
17.5
25.9
33.3
28.0
3!*. 0
1*6.9
52.5
68.3
respiratory rates
of 3 species
in pure culture
(^1/mg/hr)
0.2l4
0.19
0.23
x 0.22
0.28
0.18
0.23
X 0.23
0.1*0
0.30
0.36
x 0.36
O.U
0.50
0.57
x 0.50
Overall respiratory rate
of 3 species
in mixed culture
fyiL/mg/hr)
0.16
0.12
O.lU
O.ll*
0.17
** m -•- |
0.12
0.16
0.15
0.32
0.18
0.2U
0.25 .
0.37
0.1*0
0.53
O.U3
-------
"between 10 C and 15 C in separate cultures only, but all other
comparisons showed no significant difference.
When the experimental procedure was reversed (at 10 C) and the
species were mixed first and then separated, the results obtained
were 0.233 and 0.322 yl/mg/hr, respectively. Again, the result was
highly significant (F = 18^.9^ on 1 and k d.f., P<0.00l). When two
densities were compared (Table 7) no significant differences in
respiration rate could be demonstrated.
Growth
The growth of worms over a 6 month period under various conditions
is documented in Tables 8 and 9, from which it is clear that growth
varies in relation to the presence or absence of other species. An
initial consideration of growth in pure culture only shows that,
according to a one-way analysis of variance, there is no significant
difference in growth between T. tubifex and L. hoffmeisteri, but
P. multisetosus grew less than either. T. tubifex grows significantly
(at the 5$ level) better than P. multisetosus when they are mixed as
a pair, and so does L^ hoffmeisteri (P<0.01). This result is obtained
for the third time when considering the growth of the same pairs when
all 3 species are mixed together, but the significance of the result
is at the 1% level for both comparisons using P. multisetosus.
Thus far comparisons have been based on cultures initiated with the
same number of specimens of each species (l8 in pure culture, 9
of each when paired, 6 of each when all species present). Some of
the following tests of the growth of single species under a variety
of conditions must inevitably involve comparisons based on the
results of experiments in which there were differences in the initial
numbers used. It would be impossible to create a situation in which
the total population density and the population density of each
species in separate and mixed cultures remained constant.
The growth of P. multisetosus was not significantly affected by the
presence or absence of one or other or both other species, but the
growth of the other species was often affected by the presence of
this relatively slow-growing species. L. hoffmeisteri grew more in
the presence of F. multisetosus than it did alone or with T. tubifex
(P<0.05). T. tubifex grew more in the presence of either (or both)
other species than when alone (P<0.0l). . When all 3 species were
present T. tubifex grew significantly more than it did in the
presence of just L. hoffmeisteri, but the reverse situation (L. hoff-
meisteri with T. tubifex vs L. hoffmeisteri with both other species)
made no difference to the growth of L. hoffmeisteri. Both species
grew as well in the presence of P. multisetosus as they did in the
38
-------
LO
VO
Table 7. Rate of oxygen consumption in Ail/mg/hr at IOC of
3 tubificid species at 2 population densities.
Number of worms per test vessel
Species 150 50
L. hoffmeisteri 0.2U 0.27
T. tubifex 0.31 0.33
P. multisetosus 0.6U 0.78
-------
Table 8. Gain in veight of cultures of 3 tubificid species under various
conditions as multiples of the original weights.
Culture
conditions
Pure culture
With L. hoffmeisteri
With T. tubifex
With P. multisetosus
With both other
species
L. hoffmeisteri
2.39
7.20
8.02
li.89
2.39
x ¥798
_
-
-
-
3.71*
5.39
6.80
5-96
9.1*1
x 6.26
9.98
6.32
11.33
9-75
10.72
x 9.62
7.95
7.01
13.03
8.09
8.82
x 8.98
T. tubifex
2.1*7
1.85
2.71*
3.U8
l*.3l*
x 2.98
l*.6l
5.30
5.80
7.25
6.53
x 5.90
_
_
_
^
5.13
10.55
9-97
5.29
11*. 10
x 9.01
11.06
7.31
10.60
13.1*5
11.50
x 10.78
P. multisetosus
1.5*
1.02
1.00
2.91*
1.76
x 1.65
0.31*
0.50
0.88
2.32
3.81
x 1.57
2.1*9
If. 33
6.91
1.58
1.00
It 3.26
m t
-
-
-
-
0.1*9
0.59
1.79
1.82
1^09,
x 1.56
-------
Table 9. Gain in veight of pairs of tubificid species and of a mixture of all 3 after 6 months
expressed as multiples of the original weights.
Culture
conditions
L. hoffmeisteri
plus
T. tubifex
Mixture of species
Ii. hoffmeisteri
plus
P. multisetosus
T. tubifex
plus
P. multisetosus
All 3 species
Total for 2
or 3 species
3.98
5.3U
6.1*0
6.31
8.53
x oTlT
8.75
5.57
8.88
8.U3
9-30
X 8.19
U.lU
7.6l
9.32
U.6U
8.03
x 6.75
7.67
6.5U
10.31
8.83
8.UU
x 8.36
Total for 2 species
in a mixture of all 3
8.83
7.12
11.73
10.OU
10.38
x 9.62
6.5,7
6.18
10.07
6.85
5.93
x 7.12
7.
5.
91
8.Mi
-------
mixture of all 3 species. All of this indicates considerable
influence by P. multisetosus on the other 2 species under a variety
of conditions, vhereas its own growth is not significantly changed
"by the presence of either or "both of the others.
The total production of worm tissue when two species are combined
in a single culture may now be considered (Table 9). No significant
differences in growth were observed between the 3 possible pairs,
but more worm tissue was produced by any of the pairs than by
T. tubifex or P. multisetosus alone (P<0.01). Growth of L. hoff-
meisteri alone was not significantly different from that of worms in
2 of the 3 pairs, but L. hoffmeisteri with P. multisetosus produced
more worm (P<0.05).
Again when the production of worms in paired culture is compared to
the growth of the same 2 in the presence of the third, the presence
of P. multisetosus^ stimulated more growth by the other two than
they achieved in its absence (P = O.Oll).
The mixture of all 3 species produced more worm tissue than any
species alone (P<0.01 for T. tubifex, P. multisetosus^; P<0.05 for
L. hoffmeisteri) and significantly better than the L. hoffmeisteri-
T. tubifex culture (P<0.05), but there was no significant difference
between the complete mixture and the other paired cultures.
Egestion
The % organic matter in the faeces of T. tubifex and L. hoffmeisteri^
is significantly higher than that of the original mud at all four
experimental temperatures (Table 10). Differences between the two
worm species, and temperature effects were of little significance
throughout, and the fact that the mud used at 5°C had a lower organic
content than that in the other experiments had no effect either. The
isolated results obtained using P. multisetosus showed the same
trend.
The % nitrogen was significantly higher in the faeces than in the mud
at 5°C (P<0.01) and at^lo'C and 15°C (P<0.05) for both species (Table
2), but P values at 20°C were 0.05 and 0.86 for L. hoffmeisteri and
T. tubifex respectively for the same comparison. There was no
significant difference in nitrogen values of the two sets of faeces,
and no significant effects due to temperature other than a slightly
elevated nitrogen level in the mud at 5°C, probably related to the
somewhat higher value in the mud used at that temperature. The five
values obtained from faeces of P. multisetosus were-about the same
as those for mud except for one at 15"C, which was higher.
-------
Table 10. The nitrogen, organic matter and calorific content of feces of T. tubifex and L. hoffmeisteri
at U temperatures using mud<250 ^i particle size.
Nitrogen and organic matter expressed as a %. All values are means +_S.D. N = 10-15 in each instance.
4=-
00
Parameter
% organic matter
% nitrogen
calories/gm
Temperature
C
5
10
15
20
5
10
15
20
5
10
15
20
mud
+ S.D.
6.7 + 0.8
8.0 + 1.9
7.2 + 0.6
7.1* + 1.1
0.23 + 0.01
0.22 + 0.01
0.22 + 0.01
0.21 +_ 0.01
2U3 * 8
220 + 33
2U8 + 22
236 + 6
Source of sample
feces of
L. hoffmeisteri
± S
-------
The calorific values of faeces were again significantly higher than
those of mud for both species at most temperatures (Table 6). The
difference was significant with P<0.01 for L. hoffmeisteri at 10°C
and for T. tubifex at 15°C, and P values<0.05 level were obtained
for the former at all other temperatures and for the latter at 10°C.
There were no significant differences in calorific values of faeces
of the worm species, and no significant differences due to tempera-
ture. Again, six of the seven values for P. multisetosus faeces
were higher than those of the mud.
In the experiment designed to test the effect of varying the particle
size used, the % organic matter was still higher in faeces than in
the mud (Table 11). The % nitrogen in faeces of L. hoffmeisteri
was significantly higher than in the mud in all three instances
(P<0.01 with 230 y screens but <0.05 with the other sediments), but
in the faeces of T. tubifex there was no longer a significant
difference in nitrogen levels once the two finer screens were
employed (P<0.01 using 250 y screens just as in the first experiment
at 5 C). At no time did the use of fine screens produce a situation
in which % organic matter or % nitrogen was lower in the faeces than
in the mud used as a food source, despite the fact that there was a
significant increase in both parameters for the mud sieved with 120 y
screen in place of the 250 u screen. No further significant increase
was noted when the 63 \i screen was employed. The % organic matter in
the faeces of L. hoffmeisteri showed little significant difference
in relation to the type of sediment used (P<0.05 for interactions
involving the 120 y screen, but no significant difference between
250 y and 63 y assays) and the same was true for T. tubifex. The
faeces of both worm species had substantially the same nitrogen
content regardless of the screen size in preparing the mud, and
no differences in organic content were detectable in comparisons
between the species either. When mixed cultures were used, the
percentage organic matter in the faeces was not significantly
different from that observed in pure cultures but both were signifi-
cantly higher than that of the whole mud presented as food (Table
12). Furthermore, there is a significant positive correlation
between percentage organic content of the original mud and that of faeces
(P<0.01 and P<0.05 for pure and mixed culture respectively), which is
linear according to regression analysis for the range 9-~Lk% organic
matter in the mud.
Defecation rate
Defecation rate was investigated at a number of temperatures using
three species, and at a single temperature (lO°C) for a mixture of
three species. The rate varied considerably from day to day and
experiment to experiment (Figs.lU, 15) (Appleby and Brinkhurst, 1970).
-------
Table 11. The % organic matter and % nitrogen content of three types of sediment and of the feces
of two species of tiibificid worm fed with them, (x +_ S.D. , N = 12-15).
Particle size of food
mud used as food
feces of L. hoffmeisteri
% organic matter
<120
•63
6.7±0.8 8.1+0.8 8.7+0.7
13.2+1.8 lit.7+1.8 13.0+1.6
% nitrogen
<250
'63
0.23+0.01 0.26+0.03 0.27+0.01
0.29±O.OU 0.29+0.05 0.29+0.03
feces of T. tubifex
13.2+_3.6 13.3±2.6 15.3+2.0
0.27+0.01 0.27+O.OU 0.27+O.OU
-------
o\
Table 12. % organic matter in faeces of a mixed culture of three worm species
compared to the content of faeces of the same worms in pure culture and to
the original mud. Experiments at 10 C.
Experiment
1
2
3
1*
5
Mud
8.9
9.0
7.8
13. U
13.9
Pure culture
15.0
17.2
15.5
26.3
26.0
Mixed culture
Ih.k
16.0
17.6
22. U
29.2
-------
~
-5
J
£
a
E
M
SO 2
a
£
=r.
E
*
C
30
2.0
C
n
Fif> Ik. Defecation rate of worms at i :an ^:,:njiature oT 3-7 C.
-------
---
-
i
r
k.
c
E
a
-
X
if
9
u
•
M
*—
>. 02
L.
-c
E
a
E
<
U
13O
X.
-<
,2o
m
z
-
=
<5—
-------
In early experiments some relationships between temperature and
average defecation rate were established (Fig.l6) but these were
not duplicated in later studies (those in which the analyses of the
faeces were performed) (Table 13). Preliminary efforts to investigate
the effect of varying the sediment used as food produced little effect
on the defecation rate (Table lH). No data is presented on P.multi-
setosus in this instance as very few results were obtained, and data
presented in Table 13 are based on few positive results for this species.
When the species were mixed together, defecation rate increased by
2h% (U.5 mg/mg/day versus 3.6, n = 35), a significant difference
(P = 0.03).
Assimilation
Average calorific values of 5.130, 5.17^ and 5.0266 kcal/g were
obtained for L. hoffmeisteri , T. tubifex and P ._multisetosus respect-
ively. Using this data, the sum of respiration and growth in pure
and mixed culture can be calculated.
It should be noted that respiration experiments were of very brief
duration, and that growth experiments lasted six months. Also,
short-term growth studies suggested that weight losses may occur in
3-week old cultures, so that the true duration of growth experiments
might be anything from 20-26 weeks. Nevertheless, on an annual basis
the three species in mixed culture might respire 9.38 kcal/g while
growth could account for 75.22 kcal/g. In pure culture the three
species would respire a total of 13.28 kcal/g but achieve a growth
of only 22.5 kcal/g. As there is a greater increase in growth than
is accounted for by reduced respiration in mixed culture, the pure
culture utilizes less energy than the mixed culture per unit time
per unit weight.
Total assimilation of a mixed worm population should be calculated
on the basis of 8U.6 kcal/gm/year rather than the total of 35.8
kcal/gm/year for three pure cultures. Mean standing stocks of
tubificids in Toronto Harbour are probably as high as any that can
be recorded anywhere in the world. A survey of eighty-six samples
in the harbour yielded the following averages: - 96,000 worms/m2,
20.6 g dry wt/m2, 18.2 g ash-free dry wt/m2. These averages are
the result of pooling data from a gradient along which worms varied
in abundance from over 125,000 to less than 25,000 (Brinkhurst, 1970).
The worms therefore export 200 kcals/m2/annum by virtue of their
respiratory activity. The 1550 kcals/m2/annum of worm tissue produced
may potentially be returned to the ecosystem via the activities of
predators, but some percentage of this quantity is undoubtedly recycled
through the worm population when it feeds on bacteria and on the
decomposing dead worms. In the Bay of Quinte study the ash-free dry
-------
e
25
o
E2.0
01
M
s
>, ' 5
v.
-
I
1.0
UJ
h
tt
0-L
A- P
D-T
0 2 4 6 8 10 12 14
TEMPERATURE (°C.)
Fig. 16. Possiule changes in defecation rate vith IT?
16
18
20
22
-------
Table 13. Defecation rates for tubificid worms fed on mud with <250 y particle
size (x ± S.D., n = 10-20). In mg dry faeces/mg dry worm/day.
Temperature
C
5
10
15
20
T. tubifex
k.2 ± 2.3
3.8 ± 1.7
k.5 ± 2.2
12.7 ± 10.3
Species
L. hoffmeisteri
3.U ± 1.6
5.2 ± 2.7
Ik. 9 ± 3.7
8.1 ± 5.1
P. multisetosus*
1.2 ± 1.6
3.7 ± 1.9
2.k ± 1.3
8.1 ± k.Q
* Data based on few replicates.
-------
Table lU. Defecation rates for tubificid worms fed on three different
sediments at 5 C (x ± S.D.). In mg/mg/day.
vn
rv>
Particle size
T. tub if ex
<250 y
3.6 ± l.T
L. hoffmeisteri 3-1* ± 1.6
<120 y
3.6 ± 1.2
U.O ± 2.0
<63 y
U.U ± 1.5
2.8 ± l.li
-------
weights per oligochaetes are much lower than for Toronto Harbour
(Table 15) where the polluting input probably contains more
utilizable input than at Big Bay (see below). The production and
assimilation in Toronto Harbour are calculated from respiration
data on mixed species complexes, but those for the Bay of Quinte
are not. Production data are based on the growth of mixed cultures
over six months in the laboratory for Toronto Harbour worms, that
for the Bay of Quinte on shorter-term growth determinations also
on laboratory held mixed populations. Differences between the
various estimates of production and assimilation are roughly pro-
portional to the standing stocks of worms despite the very high
levels observed in Toronto Harbour.
Imports
Attempts to study sedimentation rate in Toronto Harbour failed owing
to destruction of the equipment by shipping and/or vandals. In a
parallel study in the Bay of Quinte samples of various types were
evaluated (Johnson and Brinkhurst, 1971c) and all except the narrow
(5 cm diameter) traps collected material at roughly the same rate.
The small cylinder caught much more than the others (2.6 g/m^/day as
opposed to 0.25-0.6).
While correspondence between import and sediment respiration (which
includes the living organisms) was good along the trophic gradient
from Big Bay to Prince Edward Bay, Lake Ontario, the energy flow into
the benthos was not proportional to the total input. At Big Bay
much of the 6856 cal/m2/day ends up in the sediment, whereas only
1586 are channelled through the microflora to pass 3^5 cal on to the
benthos. In the less polluted sites lower down the system - imports
of 1512-787 cals produce throughputs to the benthos of 1180-U20 cals.
Hence the quality of the sedimented material is more important than
the overall total measured simply in terms of calories, carbon or
nitrogen. Selective feeding has already been established by studying
the composition of worm faeces. Resistance to bacterial decomposition
varies according to the biochemical nature of the sedimenting material
or allochthonous material (high for wood fibre, low for milk or sewage
for example). Hence a direct relationship between total input in
calories and the efficacy of the worm population in recycling this
cannot be made. Estimates of worm production and assimilation in a
grossly polluted situation can be made (with certain assumption) but
these cannot yet be related to total pollutional loading.
The measure of the amount of organic matter in the sediment is equi-
valent to determination of standing stocks of organisms. Organic
material is being added to and removed from the sediment by sedimenta-
tion and the activities of the organisms inhabiting it (the dead
53
-------
^
Table 15. Standing stock (g ash-free dry weight/m ), annual production and
o
assimilation by oligochaetes (in kcal/m /yr) at four stations in the Bay
of Quinte and in Toronto Harbour. (Values for Bay of Quinte means for 2
annual periods during 1967-68).
Big Bay Glenora Conway Lake Ontario Toronto Harbour
Production 5-9 90.0 h.6 2.8 1,5^9.5
Assimilation 8.6 132.5 9.8 7.0 1,7^2.8
x g ash-free 0.12 1.6l 0.36 0.32 18.3
dry wt/m
-------
bodies and excreta of the same returning materials to the sediment
continuously). In our initial vork with concentrations and flux
rates of amino acids and sugars in the sediment and the overlying
water column, it is apparent that flux rates and ambient concen-
trations are in no way correlated. Hence one cannot judge the
activity of an aquatic system "by examining the concentration of
materials in storage within it. Some knowledge of flows around
(for materials) or through (for energy) the system is required in
order to compare activity.
In the Bay of Quinte study, macrobenthos biomass appeared to be
adjusted to the utilizable import consistent with a turnover rate
determined by temperature i.e. P = B T2
10
where P = production, B = biomass, T = mean temperature. Standing
stock and production were not closely related in this study, but
may be used in relation to temperature data to predict production
levels in the Great Lakes (Johnson and Brinkhurst, 1971c).
Nitrogen
We cannot therefore attempt to fulfill our original objective in terms
of calories, but as it has been calculated that the contribution of
nitrogen to Toronto Harbour might be 830 tons per annum in 1969
(data from Ontario Water Resources Commission, Ontario - Brinkhurst,
1970), we could examine the use of nitrogen by the worm population.
A tubificid worm consists of between 55 to 60 percent protein
(Whitten and Goodnight, 1966) and nitrogen is 16 percent of protein.
The average standing stock of worms in Toronto Harbour is 20.7 g/m2
dry weight, of which 11.8 g/m2 (57/0 is protein, 1.89 g/m2 is nitrogen.
The annual turnover rate is about fifteen times the original standing
stock for mixed cultures (Table 9) which gives us an annual throughput
of nitrogen of 28.35 g/m2 in Toronto Harbour. The total area of the
harbour is 3,728,000 m2, so that the standing stock and throughput
of nitrogen overall represents 70^6 kg and 105,689 kg respectively,
i.e. roughly 7 and 106 tons in relation to the total input of 830 tons.
As this imported tonnage enters at one restricted point in the harbour
(the Don River - Fig.l) it is not uniformly available to the worm
population. Much of it must be sedimented and probably thereby
exported in the dredging operation that is carried out in that area.
However, the densest worm populations are also in that neighbourhood,
with a standing stock of 142.7 gm (250,000 worms) per m2 (and hence a
minimum nitrogen concentration and throughput of 3.9 g/m2 and 58.5 g/m2
or about twice the average). The nitrogen utilization of this zone
of Toronto Harbour would approximate to 1.5 tons or 22 tons if the
area of the zone be taken to be one tenth of the whole harbour.
55
-------
SECTION VII
DISCUSSION
There are a number of implications to be derived from a considera-
tion of the results obtained herein, and these relate to a set of
assumptions inherent in many of the studies of energy flow in
ecosystems.
The quality as well as the quantity of material entering a system
as allochthonous material or produced within it as autochthonous
material is important in determining the nature of the organisms
present and the efficiency of cycling material or passaging energy
through the system. In the Bay of Quinte maximum production of
benthos does not occur where import in terms of carbon or calories
is greatest. Bacterial production occurs in nature in a multiple-
substrate system in which the biochemical identity of the substrates
is more important than the total amount of carbon or energy resources
available. Worms, too, exhibit selectivity in their feeding as
indicated by the apparent increase in organic matter, nitrogen and
calorific value of faeces as opposed to the whole mud upon which
they were fed.
Tearing an ecosystem apart and determining energy flow in the labora-
tory species by species ignores the possibility of interspecific
interaction. Our work on mixed cultures makes it clear that respira-
tion and growth of mixed cultures of worms are significantly different
from the values obtained when those species, or even those same
individuals, are maintained in isolation. How general this sort of
effect is we do not know, but we suspect it may involve other benthic
organisms at least.
In our study of the use of bacteria as food for worms (Wavre and
Brinkhurst, 1970) we indicated that worm species differ in their
ability to digest the spectrum of bacteria available to them so that,
even if there is no discrimination at ingestion, the faeces differ
in bacterial composition. It is possible to conceive of a system
in which worms actively seek out the faeces of other species which
may contain a high proportion of a preferred bacterium. If that were
so, worms would spend time searching rather than eating in the absence
of other species.
As the reduction in respiratory energy flow in mixed cultures is less
than the weight gain, the suggestion is that more time was spent
feeding than burrowing in the mixed culture. The energy saved in
respiration added to that obtained by production in pure culture is
57 Preceding page is blank
-------
less than the production value in mixed culture, so that there has
been an increase in food ingested and/or the efficiency of its
utilization. In order to test this hypothesis, we examined defeca-
tion rates in mixed and pure populations at the same time. We found
that the organic matter in faeces did not change but that there was
a 2k% greater flow of faeces in mixed populations than in pure.
Furthermore, the assimilation efficiency (assimilation in relation
to ingestion) increased by over 6%, indicating that a preferred food
had been ingested or that some other factor increased its assimila-
bility.
These changes indicate that energy and materials budgets for species
cannot simply be summed to yield budgets for species associations
found in nature. In order to determine the effect of the sludge-
worm population on the harbour ecosystem we would have to know the
quantity of useable imported material arriving at the sediments
along the gradient Keating Channel - Hanlan's Point, the total being
of relatively little significance. We would also have to know the
rate of utilization of the worm population by predators and the
degree to which worm tissue is simply recycled through the bacteria
after death.
The production rates and nitrogen values established allow us to
suggest that such large worm populations have a significant potential
as sources of material and energy retrieval from what we might be
tempted to regard as a sink. The effect of irrigation of those
sediments by the worms further enhances their importance in all
probability.
58
-------
SECTION VIII
ACKNOWLEDGEMENTS
The work reported here was carried out under the direction of the
Project Director, Drs. K.E. Chua, M.G. Johnson, N. Kaushik, and
L.W. Wood. Mrs. C.C. Ho and Mrs. A. Ma provided technical
assistance and the secretarial work was undertaken by Mrs. I.
Govers and Mrs. M. Thinh. Dr. J. Paloheimo provided statistical
advice. Miss S. Dymond Q.C. was of inestimable assistance in
preparing applications and reports.
We would like to acknowledge the continued interest and encoura-
gement shown to us by Dr. C.F. Powers, our E.P.A. Project Officer.
Funds derived from the Canadian National Research Council were also
used in this project. We acknowledge the assistance of the
technical personnel of the Department of Zoology, University of
Toronto, and the contribution of the Chairman, Dr. D.A. Chant, in
making these facilities available to us.
59
-------
SECTION IX
REFERENCES
AMERICAN INSTRUMENT CO. 1959. The determination of nitrogen by
Kjeldahl procedure including digestion, distillation,
and titration. Aminco Rpt. No. 10U. hpp.
APPLEBY, A.G., and R.O. BRINKHURST. 1970. Defecation rate of
three tubificid oligochaetes found in the sediment of
Toronto Harbour, Ontario. J. Fish. Res. Bd Canada
27: 1971-1982.
ASSOCIATION OFFICIAL AGRICULTURAL CHEMISTS. 1965- Methods of
analysis. 10th ed. Washington, B.C. 957pp.
BENNETT, E.A. 1970. Investigations of daily variations in chemical,
bacteriological, and biological parameters at tvo Lake
Ontario locations near Toronto. II. Bacteriology. Proc.
12th Conf. Great Lakes Res. 21-38.
BRINKHURST, R.O. 1969- Taxonomy and Biology of Sludge Worms.
Terminal Report 009^0. U.S. Dept. Interior. F.W.P.C.A.
BRINKHURST, R.O. 1970. Distribution and abundance of tubificid
(Oligochaeta) species in Toronto Harbour, Lake Ontario.
J. Fish. Res. Bd Canada 27: 1961-1969.
BRINKHURST, R.O., K.E. CHUA, and E. BATOOSINGH. 1969- Modifications
in sampling procedures as applied to studies on the
bacteria and tubificid oligochaetes inhabiting aquatic
sediments. J. Fish. Res. Bd Canada 26: 2581-2593.
BRINKHURST, R.O., and E.G.M. JAMIESON. 1971. Aquatic Oligochaeta
of the World. Oliver and Boyd. 86Upp.
BRODY, S. 19^5. Bioenergetics and Growth. Reinhold. 1023pp.
BRIDGES, T.G. 1970. Investigations of daily variations in chemical,
bacteriological, and biological parameters at two Lake
Ontario locations near Toronto. -I. Chemistry. Proc.
12th Conf. Great Lakes Res. 750-759.
HARGRAVE, B.T. 1971. An energy budget for a deposit-feeding amphipod.
Limnol. Oceanogr. 16: 99-103.
HUGHES, R.N. 1969. Appraisal of iodate-sulphuric acid wet-oxidation
procedure for the estimation of the caloric content of
marine sediments. J. Fish. Res. Bd Canada 26: 1959-196*1.
HYNES, H.B.H. I960. Biology of Polluted Waters. Univ. of Liverpool,
Liverpool University Press.
IVLEV, V.S. 1939. Transformation of energy by aquatic animals.
Coefficient of energy consumption by Tubifex tubifex
(Oligochaeta). Int. Rev. Ges. Hydrobiol. 38: 1^9-^58.
JACKSON, M.L. 1958. Soil Chemical Analysis. Prentice-Hall Inc.
U98pp.
61
-------
JOHNSON, M.G., and R.O. BRINKHURST. 1971c. Benthic community
metabolism in Bay of Quinte and Lake Ontario. J. Fish.
Res. Bd Canada 28: 1715-1725-
MICHALSKI, M.F.P. 1970. Investigations of daily variations in
chemical, bacteriological, and "biological parameters at
tvo Lake Ontario locations near Toronto. III. Biology.
Proc. 12th Conf. Great Lakes Res. 69-79.
SNEDECOR, G.W., and W.G. COCHRAN. 1968. Statistical Methods. 6th
ed. The Iowa State Univ. Press, Ames, Iowa.
STEEL, R.G.D., and J.H. TORRIE. I960. Principles and Procedures
of Statistics. McGraw-Hill Book Co. Inc. USlpp.
WAVRE, N., and R.O. BRINKHURST. 1970. Interactions between some
tubificid oligochaetes and bacteria found in the sediments
of Toronto Harbour, Ontario. J. Fish. Res. Bd Canada
28: 335-3U1.
WRITTEN, B.K., and C.J. GOODNIGHT. 1966. The comparative chemical
composition of two aquatic oligochaetes. Comp. Biochem.
Physiol. 17: 1205-1207.
62
-------
SECTION X
PUBLICATIONS
Publications produced as a result of this project.
BRINKHURST, R.O., and K.E. CHUA. (in Prep.). Production studies
of tubificid worms in pure and mixed cultures.
BRINKHURST, R.O., K.E. CHUA, and N.K. KAUSHIK. 1972. Interspecific
interactions and selective feeding by tubificid oligo-
chaetes. Limnol. Oceanogr. IT: 122-133.
CHUA, K.E., and R.O. BRINKHURST. (In Prep.). Influence of inter-
specific interactions on the respiration of tubificid
oligochaetes.
WAVRE, N., and R.O. BRINKHURST. 1971. Interactions between some
tubificid oligochaetes and bacteria found in the sediments
of Toronto Harbour, Ontario. J. Fish. Res. Bd Canada
28: 335-3U1.
Publications produced as a result of associated projects.
APPLEBY, A.
BRINKHURST,
BRINKHURST,
BRINKHURST,
JOHNSON, M.
JOHNSON, M.
JOHNSON, M.
G., and R.O. BRINKHURST. 1970. Defecation rate of three
tubificid oligochaetes found in the sediment of Toronto
Harbour, Ontario. J. Fish. Res. Bd Canada 27: 1971-1982.
R.O. 1970. Distribution and abundance of tubificid
(Oligochaeta) species in Toronto Harbour, Lake Ontario.
J. Fish. Res. Bd Canada 27: 1961-1969.
R.O., and K.E. CHUA. 1969. Preliminary investigation
of the exploitation of some potential nutritional
resources by three sympatric tubificid oligochaetes. J.
Fish. Res. Bd Canada 26: 2659-2668.
R.O., K.E. CHUA, and E. BATOOSINGH. 1969. Modifications
in sampling procedures as applied to studies on the bacteria
and tubificid oligochaetes inhabiting aquatic sediments. J.
Fish. Res. Bd Canada 26: 2581-2593.
G. , and R.O. BRINKHURST. 1971a. Associations and species
diversity in benthic macroinvertebrates of Bay of Quinte
and Lake Ontario. J. Fish. Res. Bd Canada 28: 1683-1697.
G., and R.O. BRINKHURST. 1971b. Production of benthic
macroinvertebrates of Bay of Quinte and Lake Ontario. J.
Fish. Res. Bd Canada 28: 1699-171^.
G. , and R.O. BRINKHURST. 1971c. Benthic community meta-
bolism in Bay of Quinte and Lake Ontario. J. Fish. Res.
Bd Canada 28: 1715-1725.
63
-------
SECTION XI
APPENDIX
Appendix 1 Temperature and oxygen data
Appendix 2 Percent N2 and organic matter in sediment sampl
-------
APPENDIX 1
Temperature and Oxygen Concentrations
(March - December, 1969 - measurement
from Toronto Harbour (Hanlan's Point)
of top and bottom water at sampling site
taken between 1000 to lUOO hours). Data
•
(% saturation)
Date
19/3/69
1VV69
30/U/69
15/5/69
27/5/69
U/6/69
11/6/69
18/6/69
25/6/69
2/7/69
9/7/69
16/7/69
23/7/69
30/7/69
7/8/69
12/8/69
18/8/69
27/8/69
1*79/69
10/9/69
19/9/69
29/9/69
22/10/69
13/10/69
2V11/69
22/12/69
Temperature
Top
1.5
9.8
10.0
12.2
13.U
11. U
lU.U
lit. 2
15.6
16.5
17.0
20.8
21.8
21.7
23. U
20.0
18.6
19.8
21.0
19.7
13.8
15. k
8.2
7-1
i».o
0.60
c
Bottom
2.5
6.2
8.6
8.9
10.8
10.0
11.8
12.6
12.7
15.0
lit. 9
17.5
20. U
20.8
20.1+
17.0
16.5
16.6
19. !»
17.3
11.-8
Ih.k
8.0
7.1
i*.o
0.70
Oxygen
Top
ca.130
112
115
125
127
98
122
105
109
119
132
112
117
65
90
117
130
116
117
99
133
116
105
107
107
125
Cone. (% !
Bot'
ca.130
97
98
101*
111
92
108
95
85
76
90
65
72
25
9
1*9
80
53
87
51
100
9U
99
105
107
125
66
-------
APPENDIX 2. A.
Percentage of-Kg by weight of dry sediment (60 C) (X ± 95j! c.l., n = 6) Samples from
Toronto Harbour Zones I-1*, July, August, September 1970.
Zone 1. July 17, 1970 August 18, 1970
September 18, 1970
0-2 cm
2-1* cm
l*-6 cm
6-8 cm
8-10 cm
Zone 2.
0-2 cm
2-1* cm
l*-6 cm
6-8 cm
8-10
Zone 3.
0-2 cm
2-1* cm
k-6 cm
6-8 cm
8-10 cm
Zone 1*.
0-2 cm
2-1* cm
k-6 cm
6-8 cm
8-10 cm
O.l6l ± 0.005
o.ll*0 ± O.OOl*
O.lUO ± 0.005
o.iUo ± o.ooi*
0.121* ± O.OOl*
0.135 ± 0.009
0.119 ± 0.007
0.109 ± 0.005
0.120 ± 0.008
0.102 ± 0.006
0.212 ± 0.030
0.205 ± 0.010
0.183 ± 0.010
0.176 ± 0.015
0.169 ± 0.006
0.3^5 ± 0.03l»
0.321* ± 0.021
0.275 ± 0.008
0.173 ± 0.017
0.129 ± 0.022
0.177 ± 0.027
0.176 ± 0.027
0.166 ± 0.028
0.159 ± 0.030
0.157 ± 0.0^0
0.160 ± 0.008
0.158 ± 0.006
0.156 ± o.oio
0.11*8 ± 0.017
0.138 ± 0.012
0.202 ± 0.013
0.185 ± 0.008
0.188 ± 0.005
0.175 ± O.OOU
0.166 ± 0.009
0.3U3 ± 0.013
0.321 ± 0.019
0.275 ± 0.036
0.20U ± O.OlU
0.197 ± 0.010
0.171 ± 0.007
0.153 ± 0.021
0.165 ± 0.029
0.167 ± O.OlU
0.170 ± 0.010
0.177 ± 0.015
0.155 ± O.OOit
0.11*2 ± 0.011
0.131* ± 0.009
0.129 ± O.OOU
0.162 ± 0.019
0.157 ± 0.021
0.157 ± 0.015
0.159 ± 0.010
0.173 ± 0.008
0.383 ± 0.027
0.357 ± 0.026
0.316 ± 0.018
0.278 ± 0.011
0.219 ± 0.026
67
-------
APPENDIX 2. B.
Percentage of organic matter in samples of sediment from Toronto Harbour Mean values +
95$ confidence limits. Sediment dried at 60 C ignited at 500 C. No corrections
applied. Zones l-b, July, August, September 1970.
Zone 1.
0-2 cm
2-1* cm
l*-6 cm
6-8 cm
8-10 cm
Zone 2.
0-2 cm
2-1* cm
l*-6 cm
6-8 cm
8-10 cm
Zone 3.
0-2 cm
2-1* cm
U-6 cm
6-8 cm
8-10 cm
Zone 1*.
0-2 cm
2-1* cm
l*-6 cm
6-8 cm
8-10 cm
July 17, 1970
6.90 ± 0.16
6.50 ± 0.27
6.98 ± 0.69
7.21 ± 0.65
6.28 ± 0.33
6.15 ± 0.1*9
5.79 ± 0.27
5.68 ± 0.60
6.20 ± 0.2k
5.2k ± 0.27
7.1*5 ± 0.70
7.25 ± 0.58
7.65 ± 0.2U
7.6l ± 0.28
7.13 ± 0.21
10.32 ± 0.79
9-52 ± 0.3l*
8.33 ± 0.1*3
5.1*1* ± 0.71
It. 09 ± 0.72
August 18, 1970
9.15 ± 0.95
9.21* ± o.37
8.5!* ± 0.52
7.1*0 ± 0.1*9
8.21* ± 0.61*
6.99 ± 0.26
6.68 ± 0.15
6.50 ± 0.19
6.00 ± 0.1*5
5.86 ± 0.1*7
7.63 ± 0.1*0
7.08 ± 0.16
7.13 ± 0.07
6.89 ± 0.28
6.62 ± 0.20
9.5l* ± 0.19
8.60 ± 0.1*0
7.75 ± 0.93
6.28 ± 0.1+2
• 6.1*9 ± 0.1*2
September 18, 1970
7.30 ± 0.27
7.38 ± 0.1*1
6.69 ± 1.6U
7.32 ± 0.82
7.26 ± 0.25
7.07 ± 0.37
6.1*9 ± 0.21
6.1*6 ± 0.3l*
6.30 ± 0.29
6.18 ± 0.28
7.80 ± 0.33
7-91 ± 0.32
8.12 ± 0.22
8.18 ± 0.36
7-98 ± 0.35
9.81* ± o.27
9.55 ± 0.31*
8.80 ± 0.31
8.28 ± 0.38
6.63 ± i.oo
68
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SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
I. Report No.
3. Accession No.
fi W
4. Title
The Role of Sludge Worms in Eutrophication
7. Author(s)
R. 0. Brinkhurst
9, Organization
Department of Zoology
University of Toronto
Toronto, Ontario, Canada
12. Sponsoring Organization avlronmental Protection Agency
15. Supplementary Notes
Environmental Protection Agency report
number EPA-R3-72-004, August 1972.
9. PtrfotmiagOrgfainttiea'
Report No. '
10. Project No.
16010 EOQ
//. Contract/ Grant No.
In grossly polluted Toronto Harbour, Lake Ontario, worm populations (x 96,000
18.3 g AF dry vt,/m2) assimilates 1,7^-3 kcals/m^/yr, produces 1550 kcals, 7 tons
nitrogen standing stock of worms circulates 830 tons/yr of total input 830 tons.
Production and respiration values for mixed species cultures differ markedly from
those of pure cultures. Worms feed selectively, digest bacteria selectively,
actively irrigate sediments. They retrieve materials from the energy sink via
production and irrigation. Production of benthos depends on quality of sedimenting
material, not just total energy or material content.
17a. Descriptors
*Benthos, *sediment, *Ecology, *Energy, ^Nitrogen, eutrophication, aquatic
microorganisms, water pollution, indicators, respiration, cycling nutrients.
17b. Identifiers
*Tubifex tubifex. *Limnodrilus hoffmeisteri, *Peloscolex multisetosus, sludge
worms, Laurentian Great Lakes, Toronto Harbour.
17c. COWRR Field & Group
18. Availability
19. Security C7««.
(Report)
20. Security CI»M,
(Page)
Abstractor R. Q. Brinkhurst \iastitutiott University of Toronto
21. No. of
Pages
22. Price
Send To:
WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON, D. C. 2O240
WRSIC 102 (REV. JUNE 1971)
GPO 913.261
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