United States
                     Environmental Protection
                     Agency
 Environmental Research
 Laboratory
 Duluth MN 55804
                     Research and Development
 EPA-600/S3-84-016  Mar 1984
&EPA          Project  Summary

                     The  Nutritional
                     Ecology of  Great  Lakes
                     Cladophora glomerata
                     Gerald C. Gerloff and J. Vic Muth
                      Various  bioassays,  primarily plant
                    analyses,  were  utilized to  evaluate
                    relative nutrient supplies and primary
                    growth limiting nutrients for Cladophora
                    glomerata growth in parts of Green Bay,
                    Lake Michigan, known to differ marked-
                    ly in degree of pollution. Preliminary
                    studies indicated that emphasis should
                    be placed on evaluations of five nutri-
                    ents: phosphorus, nitrogen, boron, sul-
                    fur, and vitamin B,. The bioassays in-
                    dicated that phosphorus very likely is
                    the critical nutrient in nuisance  C.
                    glomerata  growths and that  at times
                    phosphorus supply actually is reduced
                    to  growth-limiting concentrations.
                    However, the possibility that vitamin B,
                    may at times be critical for C. glomerata
                    cannot as yet be eliminated.
                      The bioassays employed (total P, hot-
                    water-extractable  P,  and  alkaline
                    phosphatase activity)  were in agree-
                    ment and consistent in indicating that
                    phosphorus availability  limited  C.
                    glomerata  growth.
                      In further development of  plant
                    analysis  as a bioassay, nitrogen  and
                    phosphorus critical concentrations were
                    demonstrated to be relatively constant
                    in C. glomerata of different ages  and
                    grown under various  environmental
                    conditions which would affect the rate
                    and amount of growth.
                      A requirement for vitamin B,2 and very
                    high requirements for sulfur and boron
                    were confirmed as unusual nutritional
                    features of C. glomerata. Comparisons
                    with the requirements for other green
                    and blue-green algae  established  the
                    uniqueness of the high sulfur require-
                    ment for C. glomerata. There was no in-
 dication of sulfur deficiency in Clado-
 phora sp. from the Great Lakes.
   Data obtained from solution replace-
 ment cultures indicated that, even when
 adequate total phosphorus is available,
 the growth of  C. glomerata becomes
 less than optimum at phosphorus solu-
 tion concentrations of 0.014 ppm and
 less, and at potassium and calcium con-
 centrations below 0.18 and 0.24 ppm,
 respectively. This supports the concept
 of critical concentrations in the water
 for optimum C. glomerata growth.
  Trace element studies indicated that
 C.  glomerata  requires  an inorganic
 nutrient not generally recognized as
 essential  for plant growth. The alga
 responded positively and significantly to
 a mixture of elements suspected to be
 essential. However, systematic elimina-
 tion of elements from the mixture failed
 to identify one element as responsible
 for the yield increases. The situation is
 more complex than anticipated.
  The culture and nutrition of Nitzschia
 palea, a very common diatom in the
 Great Lakes, was investigated. Silicon
 concentrations  well  above those in
 available media were  essential for suc-
 cessful laboratory growth of /V. palea.
  Various algae, primarily from  Lake
 Michigan, failed to produce inhibitors of
 C. glomerata growth to a degree that
 would suggest they are important in the
 ecology of C. glomerata in the Great
 Lakes.
  Laboratory studies were initiated on
the toxicity  of  heavy metals to  C.
glomerata.
  This report covers the period May 1,
1976 to September 30, 1978.

-------
   This Project Summary was developed
by  EPA's Environmental Research
Laboratory, Duluth, MN. to announce
key findings of the research project that
is fully documented in a separate report
of the same title (see Project Report
ordering information at back).

Introduction
   The pollution  of the  Great Lakes with
municipal and industrial wastes has resulted
in increased  growths of nuisance algae.
Filamentous  green  algae in  the genus
Cladophora are among  the most trou-
blesome  of the  nuisance organisms. The
development of measures for the reduction
of the  Cladophora  growths, based on
nutrient limitation,  will be facilitated by an
understanding of the importance of specific
nutrients in the growth of Cladophora, i.e.,
the  nutritional ecology of Cladophora.  A
primary goal of this  project has been to iden-
tify  the  nutrients,  both inorganic and
organic, most likely to limit and control the
growth of C.  glomerate in Lake Michigan.
A second goal was  to continue experiments
on the  nutrition of C.  g/omerata. Plant
analysis was the diagnostic technique used
in the study.
   For the  bioassays, samples of C. g/o-
merata and of  lake  water were  obtained
primarily at five Lake Michigan sites, four of
the sites  on the Green Bay  side  of Door
County, and a fifth on the Lake Michigan
side. The sites were selected to represent a
range of pollution and fertility resulting from
the entry of the Fox River into lower Green
Bay.
  C. g/omerata samples were obtained by
clipping filaments,  indicated as healthy by
their green color, from heavy growths close
to rocks,  the  shore,  or   from  rock-
breakwaters which extended out  from the
shore. The algae samples were  rinsed  in
distilled  water to  remove contaminating
debris. Samples  were hand-squeezed and
transported to the laboratory under refrigera-
tion. They were oven-dried and ground in a
Wiley mill. Analyses for N, P,  S and B were
by  generally   accepted   quantitative
techniques.
  In  the plant analysis bioassay, reduction
in the supply of an element to a growth con-
trolling level for a particular species at a par-
ticular site is indicated by a concentration of
the element in a sample of the species at or
below the  critical  concentration, the
minimum plant concentration which permits
optimum growth. A concentration above the
critical level indicates that the algae from the
site sampled were adequately supplied with
the element.
   In  the differential nutrient enrichment ex-
periments aliquots of lake water from specific
sites  were  enriched  with  the  various
nutrients. Concentrations of added nutrients
were those in the synthetic culture medium
of Cladophora. One or several nutrients were
omitted in each treatment. After innocula-
tion with the C. glomerata, cultures were in-
cubated  for 21 days  under  continuous
fluorescent  light at  a  temperature  of
23 ± 1 °C. Any element  present in the lake
water in an  amount adequate to support
50% of the yield in the complete medium in
lake water was  considered unlikely to limit
algae growth under field conditions. Of the
nutrients tested, this eliminated  calcium,
magnesium, manganese, molybdenum, zinc,
copper, boron,  sulfur and vitamin  B12 as
critical in C. g/omerata growth. Every enrich-
ment test indicated that four nutrients (N,
P, Fe and vitamin B,) were most likely to limit
growth of C. glomerata.
  Yields of C. g/omerata in the enrichment
cultures were slightly better when nutrients
were added to lake water rather than distilled
water. This suggested that lake water con-
tains  some  unrecognized essential  trace
nutrient, or that the ratios of nutrients in the
synthetic medium are not optimal.
  Overall results indicated that phosphorus
is the key nutrient in nuisance growths of C.
g/omerata in Green Bay of Lake Michigan.

Conclusions
1.  C. g/omerata becomes phosphorus defi-
    cient in parts of Green Bay during  late
    summer. Phosphorus seems to be the
    key  nutrient in  the development of
    nuisance C. g/omerata growths.
2.  There is a  close correlation  between
    nutrient inputs to Green Bay and  the
     development of phosphorus deficie
     in C. g/omerata.
3.   C.  g/omerata has extremely high ,
     unique requirements for  sulfur  i
     boron, but  these  elements  are
     critical in the nutritional ecology of
     organism.
4.   While phosphorus very likely is the I
     factor in   nuisance C.  g/omer,
     growths, the possibility that vitamin
     is a critical nutrient cannot be elimina
     at this time.
5.   Relatively simple bioassays are availa
     for evaluating nutrient supplies for
     g/omerata.
6    Critical nitrogen and phosphorus cc
     centrations,  which  are  the basis
     nutrient assays through plant analys
     are relatively constant for C. glomen
     under a variety of environmental cc
     ditions and at various stages of grow
     This is a critical point of support 1
     plant  analysis as a reliable  nutrie
     bioassay.
7.   C. glomerata growth seems to be le
     than  optimal when the phosphor
     solution  concentration  decreases
     0.014 ppm and below.
8.   Inhibitor production by common algi
     probably is not a major factor in tl
     ecology of C. glomerata.
9.   An adequate supply  of soluble silicon
     a  critical   factor in  the successf
     laboratory  culture of the  diatom Nit
     schia palea. Media commonly used fi
     culturing blue-green and green alg<
     contain inadequate silicon for optimui
    growth of the diatom.
                                        U S GOVERNMENT PRINTING OFFICE, 1984 — 759-015/76'
   Gerald Gerloff and J. Vic Muth are with the University of Wisconsin, Madison, Wl
     537O6.
   Nelson A. Thomas is the EPA Project Officer (see below).
   The complete report, entitled "The Nutritional Ecology of Great Lakes Cladophora
     glomerata,"(Order No. PB 84-136 571; Cost: $16.00, subject to change) will be
     available only from:
           National Technical Information Service
           5285 Port Royal Road
           Springfield, VA 22161
           Telephone: 703-487-4650
   The EPA Project Officer can be contacted at:
           Environmental Research Laboratory
           U.S. Environmental Protection Agency
           6201 Congdon Blvd.
           Duluth, MN 55804

-------
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use S300
                Pb   Q0003
-------