Microbial food-web structure and function in Lake Erie Influence of benthic-pelagic coupling on hypoxia in the central basin

1. COVER PAGE
Project Title:
Microbial food-web structure and function in Lake Erie: Influence of benthic-pelagic
coupling on hypoxia in the central basin
Project Period: April 1 2005 – May 1 2006.
Principal Investigator:
Hunter J. Carrick
Assistant Professor of Aquatic Ecology
The Pennsylvania State University
School of Forest Resources
8B Ferguson Building
University Park, PA 16802
Phone: 814-865-9219 Email:
Summary: We propose to evaluate the spatial and temporal variation in microbial-based
carbon, its deposition, and subsequent contribution to the seasonal development of hypoxia in
the central basin of Lake Erie. This will be determined by directly measuring the microbial
biomass, species composition, and the balance between microbial growth and loss rates
(zooplankton grazing and sedimentation) in time and space. This project will also assess
links
between changes
in
microbial population dynamics
and recent food web changes in
A.
Lake Erie through comparative
studies among sites and basins.
We believe this approach has
merit, because the production of
organic matter and its subsequent
deposition to the sediments is a
key factor that fuels hypoxia in

systems such as the Gulf of
Mexico, and these factors can in
B.
turn be more easily managed
compared with physical factors
Central basin hypolimnion
(e.g., Rowe 2001). We will
accomplish this by using state of
the art analytical techniques (flow
cytometry,
HPLC
pigment Fig. 1. A). SeaWifs image of surface water chlorophyll 
analysis, high-resolution oxygen (7/20/02) depicting typical spatial variation  (dark 
titrations) to provide estimates shading=high chl).  Red lines show boundaries for basins 
that can be used to predict B). A cross­section of the lake highlights the central 
microbial structure and function basin hypolimnion where the seasonal hypoxia occurs. 
across several temporal and
spatial scales in Lake Erie.

Carrick: Lake Erie microbial ecology and hypoxia, Page 1


2. SCIENTIFIC RATIONALE
2A) HISTORICAL BACKGROUND AND CONTEXT: Reduced phosphorus loadings to the Great
Lakes since 1970 has been credited with a return of these systems to more pristine
conditions, particularly in Lake Erie (Makarewicz and Bertram 1991). However, recent
information for Lake Erie indicates a perplexing increase in lake N and P levels, while
phytoplankton biomass has decreased (Carrick et al. 2004); this pattern that is perplexing
given that P-loadings to the lake have not changed significantly over the same time-frame
(Dolan and Richards 2003). Taken together, this suggests a decoupling between

phytoplankton and nutrients, a condition that simply runs contrary to our concept of Great
Lakes ecology and the nutrient reduction plans in place throughout the entire Great Lakes
system (e.g., Schelske et al. 1986). Some data suggests that the introduction and
establishment of exotic Dreissenid mussels may be responsible for the decoupling of
chlorophyll and phosphorus, through direct grazing on phytoplankton (Lavrenteyv et al.
1995), while simultaneously excreting biologically unavailable phosphorus (Nichols et al.
1999) that may fuel heterotrophic production (Heath et al. 1995).
Hypolimnetic oxygen depletion is a key forecasting parameter used to gauge
improvements in the water quality of Lake Erie (figure 1), because depleted oxygen levels in
Lake Erie once resulted in massive fish die-offs and changes in the lake’s gross chemistry
and biology (see Burns 1985). The reduction in phosphorus loads to Lake Erie since 1970
have been credited with a lessening in HOD rates in the lake (Bertrum 1993). However,
recent data for the lake exhibits an upward trend in HOD rates since 1995 (Rockwell and
Warren 2003). However, few measurements of annual carbon flux to the sediments have
been made since the 1980’s (Matisoff 1999), and comparatively little is know about the
balance between microbial growth and loss rates in the water column, which we know
contribute to deposition of organic matter to the benthos in the Great lakes (Schelske and
Hodell 1997).
2B) PROJECT OBJECTIVES: We propose to evaluate the spatial and temporal variation in
microbial-based carbon and its subsequent deposition and contribution to the seasonal
development of hypoxia in the central basin of Lake Erie. This will be determined by
directly measuring microbial biomass, species composition, and the balance between
microbial growth and loss rates in time and space. This project will also assess links between
changes in microbial population dynamics and recent food web changes in Lake Erie through
comparative studies among sites and basins. We believe this approach has merit, because the
production of organic matter and its subsequent deposition to the sediments is a key factor
that fuels hypoxia in systems such as the Gulf of Mexico, and these factors can be managed
(e.g., Rabalais et al. 2005). Having said this, we fully realize that physical oceanographic
factors can influence hypoxia (e.g., advection, thickness of hypolimnion), particularly in
shallow basins (e.g., Burns 1985); however, these factors are likely to be more difficult to

manage. The specific objectives of the study are: 1) measure the seasonal and spatial extent
of the subsurface algal maximum in Lake Erie, 2) determine if a benthic algal assemblage
exists in the central basin, and 3) evaluate the interaction between pelagic and benthic
microbial assemblages and their likely contribution towards HOD in the central basin.
2C) PROJECT APPROACH AND METHODS: We propose to conduct field sampling to identify
unique patterns in microbial structure and function at temporal and spatial scales in Lake

Carrick: Lake Erie microbial ecology and hypoxia, Page 2


Erie, whereas a series of experiments will be used to evaluate the mechanisms that regulate
these patterns. Monthly sampling will be conducted during spring mixing (May), early
stratification (June), mid-stratification (July), late stratification (August), and fall mixing
(September) in Lake Erie. Measurements of microbial structure (biomass, size, species
composition) will be made at all 14 NOAA stations, while functional measures (production,
growth and loss rates) will be made at four NOAA intensive sampling sites. This sampling
scheme will likely characterize the bulk of temporal (Scavia and Fahnenstiel 1987) and
spatial (Makarewicz et al. 1999) variation for the offshore region of the lake. At all lake
stations, water column profiles for temperature, PAR, dissolved oxygen, chlorophyll
fluorescence, and conductivity will be logged from surface to near bottom using a Seabird
CTD (model SBE-19). During stratification, water samples will be collected from each
thermal strata (epilimnion, metalimnion, and hypolimnion) using 8-L Niskin bottles. During
the spring and fall mixing periods (May and September), water samples will be collected
from 1-2 depths. Benthic samples will be collected at each site using a box core sampler
(0.25 m2) in order to retrieve intact (undisturbed) sediments, from which triplicate
subsamples will be collected with acrylic core tubes (surface area=13.2 cm 2). Once retrieved,
raw benthic and pelagic samples from all 14 stations will be retained for pigment, carbon,
flow-cytometry analyses (see below). The flow cytometry samples will be preserved with
1.0% paraformaldehyde (Li and Dickie 2001). Samples for microscopic counts from the four
intensive stations will be preserved with 1% glutaraldehyde (pico- and nano-sized bacteria,

algae, and protists), and with 1% Lugols (micro-sized algae and protists) for subsequent.
Objective-1: Measure the seasonal and spatial extent of the subsurface algal maximum
in Lake Erie and evaluate co-variation among members of the microbial food web
(predictive model). The
occurrence of Dreissenid
mussels
has
been
correlated with enhanced
water transparency in
portions of Lake Erie (e.g,
Holland 1993). Given this,
Carrick
(2004)
hypothesized
that
enhanced water clarity due
to mussel grazing might
promote the development of a subsurface algal maximum (SAM) in Lake Erie that could
lessen hypolimnetic oxygen depletion. Based on his 1997-98 data, a SAM was present with
a unique flora compared with the surface assemblage, although the layer did not alleviate
oxygen depletion in the eastern basin. In the central basin, Carrick et al. (2004) observed
large variation in pelagic chlorophyll concentrations (see Fig. 2; Table 1), with the greatest
values being measured in the metalimnion (Wilcoxon signed rank test z=2.00, P<0.05). Also,
algal taxonomic composition of the pelagic assemblage varied with depth and sampling date
at a single offshore site (Fig. 4), and had comparable species composition with other oligomesotrophic assemblages in the eastern basin and Lake Michigan than previously had been
observed (Carrick 2004).

Carrick: Lake Erie microbial ecology and hypoxia, Page 3

Exploratory studies will be initiated to measure the abundance and species composition
of pelagic microbial assemblages with respect to relevant in-lake environmental gradients
that we know exist (light, temperature, and nutrient conditions). Previous studies indicate that
microbial populations vary with depth in the Great Lakes (e.g., Pick and Caron 1987).
However, few estimates of
entire
microbial
assemblages have been
made to date in Lake Erie
(see Fahnenstiel et al 1998).
Because our knowledge of
microbial dynamics is often
limited by our ability to
complete
laborious
microscopic cell counts, we
will develop a model to
predict known microbial
taxonomic
composition
from
flow
cytometry
signatures (Li and Dickie
2001). Microbial cell counts will be performed only at four intensive NOAA stations, while
pigment and flow cytometry samples will be collected at all 14 sites.
Approach and Methods: Microbial abundance will be measured along environmental
gradients in Lake Erie by sampling depth profiles at all NOAA representative stations that
span the three basins (East, Central, and West) before (May), during (June, July and August),

and after (September) the onset of thermal stratification. The biomass and taxonomic
composition of the entire microbial food web will be measured using several independent
techniques. First, we will measure the gross biomass of microbes using an analysis of
photosynthetic pigments (phototrophic microbial biomass) and total carbon (total microbial
biomass). High-performance liquid chromatography (HPLC) will be used to characterize the
phytoplankton assemblage and identify major pigments that are diagnostic of dominant algae
(see Millie et al. 2002). Particulate carbon will be measured using UIC Coulometer to
estimate total microbial biomass (see Carrick et al. 1993). The difference between these two
estimates can be used to infer the contribution of heterotrophic microbes. Second, direct
microscopic cell counts will be performed to determine the biomass and species composition
of both heterotrophic and phototrophic microbes using a stratified microscopic analysis
(Carrick et al. 2000). Cell volumes will be converted to carbon estimates using standard
conversion factors (Verity et al. 1994). Last, flow-cytometry will be used to evaluate
microbial abundance of size-specific phylogenic groups (pico, nano, and micro-sized
organisms) using a Beckman Epics XL coulter counter. Counts will be performed according
to cell fluorescence, backscatter, and forward scatter characteristics of individual cells (see Li
and Dickie 2001). Initial studies indicate good correspondence between plankton cell counts
versus flow cytometry tallies (r2=0.61, p<0.001, n=28, Carrick 2003) and HPLC pigments
(see Millie et al. 2002).
Summary: Flow-cytometric signatures will be regressed against the abundance of
specific microbial taxonomic categories (bacteria, algae, and protists) in order to develop
useful predictive models that will be used to extend observations in time and space using the

Carrick: Lake Erie microbial ecology and hypoxia, Page 4


flow signatures as proxies of microbial composition. These type of data should compliment
fisheries work by researchers at NOAA (Stuart Ludsin and Doran Mason). To detect the
existence of a SAM, temporal and spatial variation in microbial biomass and dominant taxa
abundance will be evaluated using a 3-way factorial ANOVA, where station (14 sites), time

(5 dates), and depth (1-3 strata) will be considered fixed factors. Significant interactions
among factors will be subsequently reanalyzed as blocked factors.
Objective-2 Determine if a benthic microbial assemblage exists in the central basin and
evaluate its seasonal and spatial extent, as well as, its likely source. Previous studies
indicate that benthic chlorophyll concentrations in the central basin are considerable, and at
some sites they rival the standing stock of pelagic chlorophyll (Carrick et al. 2004), with
standing stocks that are high in June and decreased significantly thereafter (Fig. 3).
Microscopic analysis confirmed that viable benthic algal were present in all samples
analyzed, and that >90% of benthic algal carbon was composed of pelagic diatom species.
The seasonal pattern of benthic algal assemblages observed for the central basin appears to
be similar to that observed in nearshore Lake Michigan, where substantial concentrations of
benthic chlorophyll were measured in the May-June period and declined into the summer
(Nalepa and Quigley 1987). This was attributed this seasonal pattern to sedimentation of the
spring phytoplankton bloom
to the sediments. In the
eastern basin of Lake Erie,
benthic algal biomass was also
high early in the year and
composed
of
planktonic
diatoms, many of which
occurred as resting cells,
suggesting that the origin of
the layer was due to
sedimentation of plankton
(Carrick 2004). Thus, it seems
likely the benthic algal layer
present in the central basin has
settled out the water column;

however, previous sampling
was not adequate to confirm this pattern (i.e., did not capture the spring bloom).
Approach and Methods: We will determine the seasonality of benthic microbes in all
three basins by collecting monthly benthic samples at all NOAA stations using a box corer,
and subsampling with coring tubes (in triplicate) as described above. Also, microbial
sedimentation rates (and carbon flux) will be measured in sediment traps being deployed just
above lake bottom at 2 stations in the central basin (NOAA research by B. Eadie and N.
Hawley). Microbial biomass will be measured in all samples using pigments and carbon.
Cell counts will be performed at the five intensive stations to determine species composition
and the occurrence of diatom resting cell formation according to Sicko-Goad (1986).
Summary: Temporal and spatial variation in benthic microbial biomass and dominant
taxa abundance will be evaluated using a 3-way factorial ANOVA, where station (14 sites),
time (5 dates), and depth (1-3 strata) will be considered fixed factors. Significant interactions

Carrick: Lake Erie microbial ecology and hypoxia, Page 5


among factors will be subsequently reanalyzed as blocked factors. Cluster analysis will be
used to evaluate distribution patterns among common microbial species, from which species
groups will be inferred. In this way, we can evaluate the relative similarity of the benthic
assemblage compared with other sites-depth combinations in the central basin, including the
assemblage captured in sediment traps. If the origin of the benthic assemblage is the spring
bloom, then the benthic assemblage in May and June should be most similar with samples
taken from the lower water column and sediment traps in May.
Objective-3: Determine the balance between growth and loss factors for pelagic
microbial assemblages. We will evaluate the importance growth and loss rates (grazing and
sedimentation) in shaping the dynamics of dominant microbial taxa in Lake Erie. We will use
a series of complimentary bottle experiments to simultaneously measure growth rates and
grazing loss rates at four key NOAA stations in the lake. Previous studies indicate that bottle
experiments such as these provide reasonable estimates of growth that compare favorably

with in situ growth rates measured in the water column without bottle containment (mitotic
index, see Carrick et al. 1992).
Microbial growth and zooplankton grazing loss rates: The impact of
macrozooplankton (organisms > 153-µm in size) grazing on microbial abundance and species
composition will be determined by experimentally manipulating macrozooplankton
concentrations across a series of bottles and evaluating changes in microbial densities within
the bottles over time (Carrick et al. 1991). The relationship between the change in microbial
abundance (dependent variable) and zooplankton biomass (independent variable) will be
assessed using simple linear regression, where the slope provides an estimate zooplankton
clearance rate (µg dry wt L -1 d-1) and the y-intercept is an estimate of the growth rate (d -1) of
the prey (Lehman and Sandgren 1985). Macrozooplankton treatments are administered by
filling 4- L carboys with screened lake water, while subsequently inoculating the carboys
with subsamples of zooplankton taken from a vertical net haul. Bottles will be inoculated
with concentrations of zooplankton that approximate 0-, 1-, 1.5-, and 3 x ambient
macrozooplankton concentrations. All bottles are incubated for 24 h at ambient light and
temperature in a shipboard incubator. Initial and final subsamples for microbial abundance
(flow cytometry) and biomass (chlorophyll and HPLC pigments) will be removed from the
bottles, preserved, and enumerated to determine the abundance of heterotrophic and
phototrophic microbes (as described previously). We calculate the flux of carbon from
protozoa to macrozooplankton (µg C L -1 d-1) by multiplying the clearance rate for the
protozoan group under question by the ambient macrozooplankton biomass and, in turn,
multiplying this product by the ambient biomass of the microbial group itself.
Summary: The balance between growth and loss factors is a valuable approach to
infer dynamics that regulate the abundance of populations in nature, particularly for plankton.
We will use a simple mass balance model to assess the relative importance of growth and loss
factors (macro-zooplankton grazing and sedimentation) by comparing growth, grazing, and
sedimentation processes as mass flux estimates (ugC/m2/day). Processes will be compared
for each sampling date at two stations in the central basin to evaluate the relative export of
microbial carbon to the sediments. This carbon budget will be compared with water column
oxygen balances (see below) to corroborate results, and evaluate the contribution of pelagic

versus benthic microbial carbon make to HOD in Lake Erie.

Carrick: Lake Erie microbial ecology and hypoxia, Page 6


Objective-4: Determine the contribution of pelagic and benthic microbial metabolism to
water column oxygen balances in the central basin of Lake Erie. The redistribution of
microbial assemblages in Lake Erie in response to recent food web changes may have
implications for the water column oxygen balances and annual rates of HOD (Carrick et al.
2004). We hypothesize that algal rain from the plankton is the major of source algal biomass
to the benthos, that in turn, either contributes towards benthic production to offset respiration,
or is a source of organic matter that fuels hypolimnetic oxygen demand (HOD, see below).
This type of pattern has been observed in other large systems (e.g., Gulf of Mexico) where
seasonal pulses of plankton can contribute to the benthos (e.g., Rowe 2001).
Approach and Methods: At a two key NOAA stations in the central basin, water
column oxygen balances will be estimated by measuring diel changes in ambient
concentrations, as well as, differences between primary production and microbial respiration
(water column and sediments). Initial and final oxygen water column oxygen concentrations
will be used to estimate water column oxygen balances (Fahnenstiel and Carrick 1988).
Sampling will begin prior to daybreak (0600h) when water column CTD cast will be taken,
and water collected from the epi-, meta-, and hypolimnia will be placed into BOD bottles
(quadruplicates). Water column [O2] will be measured on whole BOD bottles (see below).
Primary production and microbial respiration will be determined using the light-dark
bottle technique (Fahnenstiel and Carrick 1988; Carrick 2004). Again, water collected from
the epi-, meta-, and hypolimnia will be placed into BOD bottles (quadruplicates) prior to
daybreak. These bottles will in turn be incubated under in situ conditions at the water depth
from which they were collected on a moored line (see Carrick 2003). All bottles will be
retrieved at sundown (1800 h) and will serve as finals to infer in situ rate processes.
Concentrations of dissolved oxygen in all bottles will be determined using a modified
Winkler technique (after Carpenter 1965), where whole BOD bottles (300 ml) will be titrated

using an automated Brinkman Metrohom potentiometric end-point detection system (Carrick
2004). Coefficients of variation among replicate samples are typically < 0.1%, with routine
blank determinations and titrant standardization. Benthic primary production and respiration
will be measured using an oxygen micro-sensor system (Unisense PA2000). The system will
be used to record time-dependent oxygen changes in triplicate core samples, from which
primary production and respiration rates will be calculated (Carlton et al. 1989).
Summary: The water column oxygen balance in the central basin of Lake Erie will be
assessed by differences in concentration in the water column associated with a discrete water
mass (Fahnenstiel and Carrick 1988). Such differences will be expressed on an areal basis for
individual water strata (epi-, meta-, and hypolimnia). Next, differences between production
and respiration will be evaluated from the bottle incubations, and these expressed in areal
terms. The degree of correspondence between water column and bottle estimates can be used
to assess the contribution of benthic versus pelagic metabolism, given that bottle effects
resulting from this approach have been found to be negliable (Fahnenstiel and Carrick 1988;
Carrick et al. 1992). Discrepancies between estimates can be used to evaluate the likelihood
of non-steady state contributions to areal metabolism (allocthanous inputs, metabolism by
metazoa, see Scavia and Fahnenstiel 1987).
References:
Bertram, P.E. 1993. Total phosphorus and dissolved oxygen trends in the central basin of Lake Erie, 19701991. J. Great Lakes Res. 19:224-236.
Burns, N.M. 1985. Erie: the lake that survived. New Jersey: Rowman & Allanhled publ.

Carrick: Lake Erie microbial ecology and hypoxia, Page 7


Carlton, R.G., G.S. Walker, M.J. Klug, and R.G. Wetzel. 1989. Relative values of oxygen, nitrate, and sulfate
to terminal microbial processes in the sediments of lake Superior. J. Great Lakes Res. 15: 133-140.
Carpenter, J.H. 1965. The accuracy of the Winkler method for dissolved oxygen analysis. Limnol. Oceanogr.
10:135-143.
Carrick, H.J. 2003. Recent changes in Lake Erie’s microbial food web: Influences on water column oxygen
balances in the Central Basin. 46 th Conference on Great Lakes Research, International Association for

Great Lakes Research, Chicago, IL. (abstract).
Carrick, H.J., Aldridge, F.J. and Schelske, C.L. 1993. Wind influences phytoplankton biomass and composition
in a shallow, productive lake. Limnol. Oceangr. 38:1179-1192.
Carrick, H.J, J.B. Moon, and G.F. Gaylord. 2004. Phytoplankton dynamics and hypoxia in Lake Erie: Evidence
for benthic-pelagic coupling in the central basin. In revision-- Journal of Great Lakes Research.
Carrick, H.J. 2004. Algal distribution pattern in Lake Erie: Implications for oxygen balance in the Eastern
Basin. J. Great Lakes. Res. 30: 133-147.
Carrick, H.J., A. Padmanabha, L. Weaver, G.L. Fahnenstiel, and C.R. Goldman. 2000. Importance of the
microbial food web in large lakes (USA). Verh. Internat. Verein. Limnol. 27: 3170-3175.
Dolan, D.M. , and Richards, R.P. 2003. Analysis of Late 90’s phosphorus loadings surge to Lake Erie. 46 th
Annual Conf., Internat. Assoc. Great Lakes Res. Abstract, p. 69.
Fahnenstiel, G.L., and Carrick, H.J. 1988. Primary production in lake Huron and Michigan: In vitro and in situ
comparison. J. Plankton Res. 10:1273-1283s
Fahnenstiel, G.L., A.E. Krause, M.J. McCormick, H.J. Carrick, and C.L. Schelske. 1998. The structure of the
planktonic food web in the St. Lawrence Great Lakes. J. Great Lakes
Heath, R.T., Fahnenstiel, G.L., Gardner, W.S., Cavaletto, J.F., Hwang, S-J. 1995. Ecosystem-level effects of
zebra mussels (Dreissena polymorpha): An enclosure experiment in Saginaw Bay, Lake Huron. J. Great
Lakes Res. 21:501-516.
Holland, R.E. 1993. Changes in planktonic diatoms and water transparency in Hatchery Bay, Bass Island area,
western Lake Erie since the establishment of the zebra mussel. J. Great Lakes Res. 19:617-624.
Lavrentyev, P.J., Gardner, W.S., Cavaletto, J.F., Beaver, J.R. 1995. Effects of zebra mussel (Dreissena
polymorpha Pallas) on protozoa and phytoplankton from Saginaw Bay, Lake Huron. J. Great Lakes Res.
21:545-557.
Lehman, J.T., and C.D. Sandgren. 1985. Species-specific rates of growth and grazing loss among freshwater
algae. Limnol. Oceanogr. 30: 34-46.
Li, W.K.W., and P.M. Dickie. 2001. Monitoring phytoplankton, bacterioplankton, and virioplankton in a
coastal inlet (Bedford basin) by flow cytometry. Cytometry 44: 236-246.
Makarewicz, J.C., and Bertram, P. 1991. Evidence for the restoration of the Lake Erie ecosystem. Bioscience
41:216-223.
Makarewicz, J.C., Lewis, T.W., and Bertram, P. 1999. Phytoplankton composition and biomass in the offshore

waters of Lake Erie: pre- and post-Dreissena introduction (1983-993). J. Great Lakes Res. 25: 135-148.
Matisoff, G. 1999. Tiem resolution of downcore chemical changes in Lake Eriesediments, pp. 75-96. In (M.
Munawar, T. Edsall, and I.F. Munawar, eds.), State of Lake Erie (SOLE)- past, present, and future,.
Backhuys Publ., Leiden, The Netherlands
Millie, D.F., G.L. Fahnenstiel, S.E. Lohrenz, H.J. Carrick, and O.Scofield. 2002a. Effect of a recurrent
sediment plume on phytoplankotn biomass and group dynamics in southern Lake Michigan. Journal
Phycology 38: 639-648.
Nichols, K.H., Hopkins, G.J., and Standke, S.J. 1999. Reduced chlorophyll to phosphorus ratios in the
nearshore Great Lakes waters coincides with the establishment of dreissenid mussels. Can.J. Fish. Aquat.
Sci. 56; 153-161.
Pick, F.R., and D.A. Caron, 1987: Picoplankton and nanoplankton biomass in Lake Ontario: Relative
contribution of phototrophic and heterotrophic communities. Can. J. Fish.Aquat. Sci. 44: 2164-2172.
Rockwell, D. C., and Warren, G.J. 2003. Lake Erie report for the Great Lakes National Program Office’s
indicators monitoring program 1983-2002. 46th Annual Conf., Internat. Assoc. Great Lakes Res. Abstract,
p. 70.
Rowe, G.T. 2001. Seasonal hypoxia in the bottom water off the Mississippi River Delta. J. Environ. Qual. 30:
281-290.
Scavia, D., and Fahnenstiel, G.L. 1987. Dynamics of Lake Michigan phytoplankton: Mechanisms controlling
epilimnetic populations. J. Great lakes Res. 13:103-120.

Carrick: Lake Erie microbial ecology and hypoxia, Page 8


Schelske, C.L., E.F. Stoermer, G.L. Fahnenstiel, and M. Haibach. 1986. Phosphorus enrichment, silica
utilization, and biogeochemical silica depletion in the Great Lakes. Can. J. Fish. Aquat. Sci. 43: 407-415.
Sicko-Goad, L. 1986. Rejuvenation of Melosira granulata (Bacillariophyceae) resting cells from the anoxic
sediments of Douglas Lake, Michigan. II. Electron microscopy. J. Phycol. 22:28-35.
Verity, P.G., C.Y. Robertson, C.R. Tronzo, M.G. Andrews, J.R. Nelson, and M.E. Sieracki, 1992: Relationships
between cell volume and the carbon and nitrogen content of marine photosynthetic nanoplankton. Limnol.
Oceanogr. 37: 1434-1445.

D) PROJECT RELEVANCE
This project will address all 8 thematic areas listed on page 2 of the RFP.
E) COLLABORATIONS
This research project draws on expertise from several collaborators. I am working with Drs.
Millie (HPLC pigments) and Dr. N. Ostrom (18-labeled Oxygen), each who are providing
analytical expertise to the project. Dr. N. Hawley will deploy sediment traps, which we have
cleared for sampling. I have spoken with Dr. S. Ludsin and Dr. D. Mason, both of which
expressed an interest in the microbial biomass and species composition data that will be
produced herein.
F) SOCIETAL RELEVANCE: This project will also assess links between changes in microbial
population dynamics and recent food web changes in Lake Erie through comparative studies
among sites and basins. We believe this approach as merit, because the production of organic
matter and its subsequent deposition to the sediments is a key factor that fuels hypoxia in
systems such as the Gulf of Mexico, and these factors can in turn be managed (e.g., Rabalais
et al. 2005). Finding from this project will lead to a better understand of the biological
factors that influence the degree and extent of the dead zone in Lake Erie.
3. PROJECT TIMELINE
Major project milestones and the date for the completion are outlined below.
Project Milestones
Project starts
Begin field sampling: Abundance & process estimates
Complete field sampling
Complete Sample Analysis: Pigment & flow cytometry
Complete Sample Analysis: Microscopic cell counts
Summarize data
Present results at IAGLR in Windsor, Ontario
Project Ends: Submit paper for publication

Dates

April 2005
May 2005
September 2005
December 2005
March 2006
April 2006
May 2006
June 2006

Carrick: Lake Erie microbial ecology and hypoxia, Page 9


5. PROPOSED VESSEL TIME NEEDS
a) Vessels: We request ship-time aboard the R/V Lake Guardian from NOAA to sample at
month intervals for five months (May to September) at 4 EPA master offshore stations in the
lake (EPA stations 91M, 43M, 78M, and 15M). The principal investigator has considerable
experience aboard this ship and served as Chief Scientist on 3 of 4 cruises in 2002 as part of
the EPA funded “Lake Erie Trophic Status Project”.
b) Time Needed: We request 5-7 days of ship-time per month to conduct sampling.
However, we will be flexible in order to dovetail with other aspects of the larger project. We
will also conduct limited sampling at nearshore stations (4-5 locations) in all three basins to
draw contrasts with offshore conditions.
c) Special Needs: We request the use of the productivity laboratory to use radiaosiotopes and
incubators space.
d) Space for Personnel: Berth and lab space are requested for the PI (Carrick), one graduate
student (Ms. Jessica Moon) and one undergraduate student (to be named later).
6. ANSWERS TO QUESTION
a) No.
b) Waste will be generated from winkler titrations that may be consider hazardous. Carrick
will make previsions to transport this material back to PSU.

Carrick: Lake Erie microbial ecology and hypoxia, Page 10


7. VITAE
Hunter J. Carrick
BUSINESS ADDRESS:
School of Forest Resources
8B Ferguson Building
The Pennsylvania State University
University Park, PA 16802
Phone: (814) 865-9219
FAX: (814) 865-3725
Email:

HOME ADDRESS:
81 Macintosh Court
Port Matilda, PA 16870
Phone: (814) 692-7558
Birthplace: Youngstown, Ohio
Birth date: June 6, 1960
Citizenship: USA

I. EDUCATIONAL BACKGROUND
Ph.D.
AQUATIC ECOLOGY: The University of Michigan, 1987-90, Ann Arbor,
Michigan. Advisors: Drs. E.F. Stoermer and R.G. Wetzel.
M.S.
AQUATIC ECOLOGY: Bowling Green State University, 1983-85. Bowling
Green, Ohio. Advisor: Dr. R.L. Lowe.

B.A.
BIOLOGICAL SCIENCES (BOTANY): The State University of New York at
Binghamton, 1983, Binghamton, NY. Advisor: Dr. G. Schumacher.
II. EMPLOYMENT EXPERIENCE
A. Professional Positions
2001-pres
ASSISTANT PROFESSOR: Aquatic Ecology, School of Forest Resources,
Pennsylvania State University, University Park, PA
1998-01
ENVIRONMENTAL SCIENTIST: Division of Watershed Research & Planning,
South Florida Water Management District, West Palm Beach, FL.
1995-98
ASSISTANT PROFESSOR: Aquatic Ecology, Department of Biology & Great
Lakes Center, Buffalo State College, NY.
1993-95
ASSISTANT PROFESSOR: Aquatic Ecosystems Ecology, Department of
Biology, San Francisco State University, San Francisco, CA.
1990-93
POST DOCTORAL RESEARCH FELLOW: Department of Fisheries and Aquatic
Sciences, The University of Florida, Gainesville, FL.
1985-90
ECOLOGIST GS-11:
U.S. Department of Commerce, Great Lakes
Environmental Research Laboratory, NOAA, Ann Arbor, MI.
B. Other Professional Appointments
2002-pres
BOARD MEMBER: International Association for Great Lakes Research
2002-pres
ASSOCIATE EDITOR: Journal of Great Lakes Research
1998-01

RESEARCH ASSISTANT PROFESSOR: Ecology, Department of Biological
Sciences, University at Buffalo, Buffalo NY.
1998-00
ADJUNCT ASSISTANT PROFESSOR: Aquatic Ecology, Department of Biology,
Buffalo State College, NY.
1986
ADJUNCT LECTURER: Department of Biology, University of Michigan,
Dearborn, MI.
III. HUMAN RESOURCES:
Courses Taught (12 Courses):
Environmental Biology (Biol 104), Principles in Ecology (Biol 313), Ecology (Biol 315),
Ecosystem Management (ERM 413w), Pollution in Aquatic Systems (ERM 432, Co-taught),

Carrick: Lake Erie microbial ecology and hypoxia, Page 11


Limnology (WFS435), Plankton Ecology (Biol 590), Great Lakes Limnology (Biol 612a,
Team-Taught), Research Principles and Paradigms (Biol 612b), Aquatic Microbial Ecology
(WFS 596), Ecosystems Ecology (WFS597B), Foundations in Aquatic Ecology (Biol 897).
Past Graduate Education: Ms. Kristen Nutile (M.S. 1996), Mr. Brent Higley (M.S. 1998),
Mr. Albert Marchi (M.S. 1998), Mr. Barrett Gaylord (M.S. 2003), Ms. Jessica Moon
(M.S. 2004).
Current Graduate Education: Ms. Sarah MacDougall (M.S.), Mr. Casey Godwin (M.S.),
and Ms. Jessica Moon (Ph.D.), and Ms. Catharine Olsen (Ph.D.).
Undergraduate Independent Studies (48 credits, *honors student): Aneal Padmanabha,
Chrissy Plotner, Nicole Horning, KellyJo Driskel*, Laurie Weaver*, Rebecca Caldwell,
Corianne Iacovelli*, Katie Nickles*, Morgan Johnston, Matt Omizek, Jamie Bosiljevac,
Lindsay Olinde*, Corey Rilk, Joshua Jackson, Sabrina Charzanowski, and Josh Jackson.
Research Technicans: Rebecca Caldwell, Leslie Nesbitt, Brent Higley, Jamie Bosiljevac,
Corey Rilk

IV. PROFESSIONAL AFFILIATIONS
Association of International Biologists (1996-present)
International Association for Great Lakes Research (1985-present)
Society of International Limnology (1998-present)
The American Society of Limnology and Oceanography (1985-present)
The Phycological Society of America (1990-present)
V. COLLABORATIONS (23 persons over past 48 months):
F. Aldridge, R. Barbiero, M.T. Brett, M.F. Coveney, P. Doering, G.L. Fahnenstiel, C.R.
Goldman, K. Havens, T. Johengen, S. Lohrenz, C. Luecke, M.J. McCormick, D.A. Millie, N.
Ostrom, A. Padmanabha, C.L. Schelske, M. Tuchman, O. Scofield, K. Steidinger, A.D.
Steinman, M. Twiss, R. VanZee, J.B. Volerman, L. Weaver.
VI. PROFESSIONAL PUBLICATIONS (6 of 45 Total, *invited paper)
*Carrick, H.J, J.B. Moon, and G.F. Gaylord. 2004. Phytoplankton dynamics and hypoxia in
Lake Erie: Evidence for benthic-pelagic coupling in the central basin. In revision-Journal of Great Lakes Research.
Carrick, H.J. 2004. Algal distribution patterns in Lake Erie: Implications for water column
oxygen balances. J. Great Lakes Res. 30: 133-147.
Carrick, R. Barbiero, and M.L. Tuchman. 2001. Variation in Lake Michigan plankton:
Temporal, spatial, and historical trends. J. Great Lakes Res. 27: 467-485.
*Carrick, H.J., A. Padmanabha, L. Weaver, G.L. Fahnenstiel, and C.R. Goldman. 2000.
Importance of the microbial food web in large lakes. Verhandlungen fur Internat.
Limnol. 27: 1-6.
Carrick, H.J., and C.L. Schelske. 1997. Have we underestimated the importance of small
phytoplankton in productive waters? Limnol. Oceanogr. 42: 1613-1621.
Carrick, H.J., and G.L. Fahnenstiel. 1995. Common planktonic protozoa in the upper Great
Lakes: An illustrated guide. Pine Press, Ann Arbor, MI. 68 p.

Carrick: Lake Erie microbial ecology and hypoxia, Page 12


CURRENT AND PENDING SUPPORT RELEVANT TO THIS PROJECT

The following information should be provided for each investigator and other senior personnel.
Failure to provide this information may delay consideration of this proposal.
Other agencies (including NSF) to which this proposal
has been/will be submitted.
Investigator: Hunter J. Carrick
Support:
Current
Pending
Submission Planned in Future
*Transfer
Project/Proposal Title: Lake Erie Trophic Status- Supplement
Source of Support: Environmental Protection Agency
Total Award Amount: $ 120,000
Total Award Period Covered: June 2003- December 2005
Location of Project: Case Western University
Person-Months Per Year Committed to
Cal: 0
Acad: 0
Sumr: 0
Support:
Current
Pending
Submission Planned in Future
*Transfer
Project/Proposal Title: Collaborative Research: Phylogeny and physioplogical ecology of
phototrophic picoplankton in Lake Erie
Source of Support: National Science Foundation
Total Award Amount: $ 370,364
Total Award Period Covered: 2005-2008
Location of Project Penn State University

Person-Months Per Year Committed to
Cal: 0
Acad: 0
Sumr: 1
Support:
Current
Pending
Submission Planned in Future
*Transfer
Project/Proposal Title: Determining the causes and influences on seasonal hypoxia in
the central basin of Lake
Source of Support: National Oceanic and Atmospheric Administration
Total Award Amount: $2,500,000
Total Award Period Covered: 2005-2010
Location of Project: University of Tennessee
Person-Months Per Year Committed to project.
Cal: 0
Acad: 0 Sumr: 1
*If this project has previously been funded by another agency, please list and furnish information
for immediately preceding funding period.

Carrick: Lake Erie microbial ecology and hypoxia, Page 13