Comparison of pelagic food webs in lakes along a trophic gradient and with seasonal aspects: influence of resource and predation

Composition and seasonal dynamics of phytoplankton, bacteria,and zooplankton (including heterotrophic flagellates, ciliates,rotifers and crustaceans) were studied in 55 lakes in NorthernGermany with different trophic status, ranging from mesotrophicto hypertrophic. Mean abundance and biomass of all groups increasedsignificantly with trophic level of the lake, but bacteria andmetazooplankton showed only a weak correlation and a slightincrease with chlorophyll concentration. Composition of phytoplanktonshowed a dominance of cyanobacteria in hypertrophic lakes, whereasthe importance of chrysophytes and dinophytes decreased withan increase in trophic status. Protozoans (heterotrophic flagellatesand ciliates) made up 24% (mesotrophic lakes) to 42% (hypertrophiclakes) of total zooplankton biomass on average, and were dominatedby ciliates (62–80% of protozoan biomass). Seasonally,protozoans can build up to 60% of zooplankton biomass in spring,when heterotrophic flagellates can contribute     

Stratification and dynamics of microbial loop communities in Lake Fryxell, Antarctica

1. Lake Fryxell, situated in the McMurdo Dry Valleys, Antarctica, offers the opportunity to study microbial loop processes in the absence of crustacean zooplankton and other higher organisms. This is the first study of Lake Fryxell to provide detailed temporal and vertical variations of microbial loop organisms.
2. Protozoan communities are concentrated around the chemocline (9–10 m) in Lake Fryxell. Phototrophic nanoflagellates (PNAN), heterotrophic nanoflagellates (HNAN) and ciliates formed deep maxima of 14 580, 694 and 58 cells mL−1 respectively. Although abundance and biomass at the chemocline was high, diversity of protozoa was low, Plagiocampa accounting for> 80% of the total ciliate biomass.
3. In the mixolimnion (4.5–8 m), protozoa were less abundant, but more diverse, with 24 ciliate morphotypes being identified within this region of the water column. Inter-annual variability of protozoan biomass and abundance was greater in the mixolimnion than at the chemocline due to more variable nutrient and prey concentrations.
4. Physicochemical gradients in Lake Fryxell were very stable because the perennial ice cover reduced wind driven currents. As a consequence, ciliate species occurred in distinct depth strata, Monodinium being most abundant directly beneath the ice cover, Askenasia having maximum abundance at 8 m and Plagiocampa dominating ciliate biomass at the chemocline. The lack of vertical mixing reduced seasonal successions of PNAN and ciliate species. Three cryptophyte species dominated the PNAN community at all times (>79% of total biomass).     

Benthic–pelagic coupling: a comparison of the community structure of benthic and planktonic heterotrophic protists in shallow inlets of the southern Baltic

1. The taxonomic composition, abundance and biomass of heterotrophic protists (ciliates, heterotrophic flagellates (HF), rhizopods and actinopods) in the sediment and water column of shallow inlets of the Southern Baltic was studied under a variety of environmental conditions during 1996–1997. A shallow, highly eutrophic station and a deeper, less eutrophic station were compared.
2. Community biomass ranged from 0.12 to 0.34 μg C cm?3 in the water column and from 1.5 to 105 μg C cm?3 in the sediment. Heterotrophic protists dominated zooplankton biomass at both stations (73% and 84% mean contribution), while they were of minor importance within the zoobenthos. Expressed per unit area, benthic biomass contributed a significant part (44% and 49%) to the total heterotrophic protistan community at both stations.
3. Although the methodology for counting ciliates and HF was focussed on a high taxonomic resolution, the results reveal some general trends in the distribution of heterotrophic protists: protozooplankton biomass was dominated by flagellates (80% mean biomass contribution) at the shallow station and by ciliates (73% mean biomass contribution) at the deep station. In the benthos at both stations, ciliates were the dominant protozoans, followed by the hitherto little‐studied rhizopods (25% and 35% mean biomass contribution) and flagellates.
4. The degree of benthic–pelagic coupling differed between taxonomic groups. Benthic and pelagic communities of ciliates showed little taxonomic overlap. In contrast, many heterotrophic flagellate species were found both in the benthos and in the pelagic. These benthic–pelagic species contributed significantly to the biomass of HF in the water column. The planktonic rhizopod community consisted of a subset of those species found in the benthos.
5. The abundance of benthic and pelagic protists was positively correlated at the shallow station, but taxonomic data indicate that the direct exchange between benthic and pelagic communities was only partly responsible.     

Dynamics and trophic roles of heterotrophic protists in the plankton of a freshwater tidal estuary

Freshwater tidal estuaries comprise the most upstream reaches of estuaries and are often characterised by the presence of dense bacterial and algal populations which provide a large food source for bacterivorous and algivorous protists. In 1996, the protistan community in the freshwater tidal reaches of the Schelde estuary was monitored to evaluate whether these high food levels are reflected in a similarly high heterotrophic protistan biomass. Protistan distribution patterns were compared to those of metazoan zooplankton to evaluate the possible role of top-down regulation of protists by metazoans. Apart from the algivorous sarcodine Asterocaelum, which reached high densities in summer, heterotrophic protistan biomass was dominated by ciliates and, second in importance, heterotrophic nanoflagellates (HNAN). HNAN abundance was low (annual average 2490 cells ml^–1) and did not display large seasonal variation. It is hypothesised that HNAN were top-down controlled by oligotrich ciliates throughout the year and by rotifers in summer. Ciliate abundance was generally relatively high (annual average 65 cells ml^–1) and peaked in winter (maximum 450 cells ml^–1). The decline of ciliate populations in summer was ascribed to grazing by rotifers, which developed dense populations in that season. In winter, ciliate populations were probably regulated `internally' by carnivorous ciliates (haptorids and Suctoria). Our observations suggest that, in this type of productive ecosystems, the microbial food web is mainly top-down controlled rather than regulated by food availability.     

The structure of the planktic microbial community in the lower reaches of the Ob River near Salekhard

We studied the distribution of the main components of planktic food web: bacteria, heterotrophic flagellates, and ciliates in the lower reaches of the Ob River near the town of Salekhard. In the early summer, the abundance, biomass, and diversity of protozoans were low; the plankton community was dominated by heterotrophic bacteria whose biomass was higher than that of phyto- and zooplankton. Downstream of Salekhard, biomass and abundance of bacterioplankton were increased due to household and industrial wastewater. The data obtained showed the importance of heterotrophic organisms in trophic dynamics and self-purification of the lower reaches of the Ob River.     

Seasonal distribution,composition and abundance of the planktonic Ciliata and Testacea of Cayuga Lake

The planktonic protozoans (Ciliata and Testacea) of Cayuga Lake were studied from September 1974 through July 1975. Monthly collections were taken at four depths (surface, 15,31 and 92 m) at each of seven stations along the 125 m depth contour. All samples were collected with a 6-liter Van Dorn bottle sampler. Densities and biomass were determined for total protozoans and total zooplankton at each depth on each sampling date. Temperature profiles at one-meter intervals were also determined on or within a few days of the zooplankton sampling.The vertical distribution of the total protozoans was directly related to temperature; maximum densities corresponded to high summer surface temperatures. Dominant protozoan taxa included Didinium nasutum, Stokesia vernalis, Codonella cratera, Strobilidium gyrans, Strobilidium sp., Strombidium viride, Paradileptus canellai, Difflugia limnetica, and unidentified ciliates belonging to the families Halteriidae, Holophryidae, Epistylidae, and Vorticellidae. Protozoans composed 69% or more of the total zooplankton density on nine of eleven dates. Protozoan dominance was most evident during winter and spring, corresponding to the near absence of rotifers and microcrustaceans. Protozoans accounted for 30% or more of the zooplankton biomass from April through June, reaching 47% in May.     

Microbial dynamics during the summer ice-loss phase in maritime Antarctic lakes

The dynamics of bacterioplankton and protozooplankton in twomaritime Antarctic lakes (Heywood Lake and Sombre Lake, SignyIsland, South Orkneys) were studied during the phase of icebreak-out (December and early January 1994/95). The lakes aresuffering animal-induced (fur seal) eutrophication, though HeywoodLake is most severely affected. Both lakes had morphologicallydiverse bacterial communities which increased during the studyperiod, reaching maxima of 80 x 10⁸ l^–1 in Heywood Lakeand 31.8 x 10⁸ l^–1 in Sombre Lake. Heterotrophic nanoflagellates(HNAN) reached a peak in late December with maxima of 40.6 x10⁸ l^–1 in Sombre Lake and 174 x 10⁵ l^–1 in HeywoodLake. Phototrophic nanoflagellates (PNAN) peaked in late Decemberafter ice loss in Heywood Lake (63 x 10⁵ l^–1), which coincidedwith a peak in a bloom of Chroomonas acuta which reached abundancesof 1.0 x 10⁸ l^–1. In Sombre Lake, ice persisted for alonger period and here PNAN reached their highest density atthe end of the study period (around 70.0 x 10⁵ l^–1). Ciliateabundance reached high levels in Heywood Lake (>60001^–1),while in Sombre Lake maximum abundance was 568l^–1. Protozooplanktondiversity was greater in the less-enriched Sombre Lake. Grazingrates of ciliates averaged 70.6 bacteria indiv.^–1 h^–1in Heywood Lake and 119.3 bacteria indiv.^–1 h^–1in Sombre Lake. The difference was a reflection of the differenttaxonomic make-up of the community in the lakes. HNAN grazingrates varied between 0.51 and 0.83 bacteria indiv.^–1 h^–1in Sombre and Heywood Lakes, respectively. Specific growth rates(r) h^–1 in Sombre Lake were 0.028 for ciliates and 0.013for HNAN, and in Heywood Lake 0.010 for ciliates and HNAN 0.012.These growth rates result in doubling times ranging between38 and 69 h for ciliates and around 55 h for HNAN.HNAN grazingon bacteria was curtailed in Heywood Lake in early January asa result of predation by microcrustacean larvae feeding on theplankton. Thus, for a short phase top-down control was apparentin the dynamics of Heywood Lake, a feature uncommon in Antarcticlake ecosystems. The impact of natural eutrophication on thesesystems is discussed in relation to other unaffected Antarcticlakes.     

Weak Coupling between Heterotrophic Nanoflagellates and Bacteria in a Eutrophic Freshwater Environment

In a study on the dynamics and trophic role of the heterotrophic nanoflagellate (HNAN) assemblage in the microbial food web of a eutrophic oxbow lake abundances, biomass, and production rates of HNAN and their potential prey organisms, namely heterotrophic bacteria and autotrophic picoplankton, were monitored for a period of 2 years. No coupling between HNAN abundance and biomass and the abundance and biomass of their picoplanktonic prey was observed for the investigation period. The ratio of heterotrophic bacterial to HNAN abundance ranged from 2.2 x 103 to 8.6 x 103 (mean: 4.2 x 103 +/- 1.8 x 103). HNAN carbon consumption could account for only 10% to 40% of bacterial secondary production. The lack of coupling between HNAN and their potential prey and the low HNAN abundance relative to bacterial abundance suggested (a) that HNAN grazing was an insignificant factor in the regulation of bacterial abundance and (b) that HNAN abundance was regulated by predation rather than by prey abundance. This hypothesis was supported by the fact that HNAN growth rates were high (in the range of 0.45 d-1 to 1.00 d-1 during spring and summer, yearly mean: 0.52 d-1), and only weakly correlated with prey abundance and biomass. The results indicated strong top-down control of HNAN and consequently a weak coupling of HNAN and picoplankton in the investigated eutrophic freshwater environment.     

On the Importance of Planktonic Protozoans in the Eutrophication Process of the Baltic Sea

Analysing the results of various authors recent studies in the pelagic region of the Baltic revealed that protozoan biomass is in the same range or even higher than metazooplankton biomass. The dominant groups of planktonic protozoans are heterotrophic pico- and nanoflagellates (various taxonomic groups), large heterotrophic flagellates (mainly dinoflagellates) and ciliates. Regularly the spring bloom of phytoplankton is accompanied by a maximum of protozoan biomass which declines in early summer as a result of intensive grazing pressure by metazooplankton and changing food conditions. The analysis of results from different stations indicated that biomasses of protozoans increase with an increasing degree of eutrophication. Several trophic levels within the microbial web should be added to the traditional view on the pelagic food web of the Baltic. Our knowledge regarding the quantitative aspect of the microbial matter flux of the Baltic is very limited up to now and complex ecological (and taxonomical) studies using standardized methods including all protozoan components are necessary. Protozoans (various trophic groups and levels), besides bacteria, should be viewed as the metabolically most active heterotrophic component in the pelagic region of the Baltic, their activity should increase with an increasing degree of eutrophication.     

Abundance and productivity of heterotrophic nanoplankton in Georgia coastal waters

The population abundances and rates of biomass production ofheterotrophic nanoplankton (HNAN) in Georgia coastal waterswere evaluated by epifluorescence microscopy. HNAN populations(mostly non-pigmented microflagellates <10 µm in diameter)ranged from 0.3 x 10³ cells ml^–1 in shelf waters 15 kmoffshore to 6.3 x 10³ cells ml^–1 in waters 0.25 km fromthe coast. There was a strong correlation (r = 0.83) betweenHNAN and free bacterioplankton population abundances, but noapparent relation (r = 0.38) between HNAN and phototrophic nanopLankton(PNAN) abundances. HNAN biomass production in estuarine andnearshore shelf waters, as estimated from increases in HNANpopulations during laboratory incubations of natural water samples,ranged from 0.10 to 0.79 mg C m^–3 h^–3, with populationgeneration times of 9.7 to 26.5 h. There was a significant linearrelation (r = 0.95) between HNAN biomass and HNAN productivity.We calculated that HNAN may graze at least 30% to 50% of dailybacterioplankton production in Georgia coastal waters.     

Planktonic ciliated protozoa: their distribution and relationship to environmental variables in a marine coastal ecosystem

The spatial distribution of planktonic ciliated protozoa, physicalvariables and potential food items were measured at northernand southern sites off the west coast of the South Island, NewZealand, to examine which variables were important in structuringthe ciliate community. Ciliates contributed 30% of total zooplanktonbiomass. Ciliate abundance was greatest within 55 km of thecoast on the northern transect, but on the southern transectthe greatest abundance was close inshore and at the stationsoffshore of the continental shelf. The ciliate community wasdominated by small oligotrichs and abundance (114–1139l^–1 was comparable with other oligotrophic marine environments.The depth of the pycnocline had a major influence on the verticaldistribution of ciliates, which were closely correlated withprofiles of phytoplankton biomass and picophytoplankton abundance,but not primary production. The results of this study suggestthat physical factors were more important than biotic factorsin influencing the distribution of protozoan ciliates. The deepmixed layer prevented the formation of deep chlorophyll a orciliate maxima. Few studies of microzooplankton have incorporatedpicophytoplankton distribution, but the importance of smallciliates and picophytoplankton suggests that these groups mayplay a pivotal role in mediating the transfer of organic matterto higher trophic levels in this marine coastal ecosystem.     

Community structure and bottom-up regulation of heterotrophic microplankton in arctic LTER lakes

Microplankton community structures and abundance was assessed in lakes at the Toolik Lake LTER site in northern Alaska during the summers of 1989 and 1990. The microplankton community included oligotrich ciliates, but rotifers and zooplankton nauplii comprised greater than 90% of total estimated heterotrophic microplankton biomass. Dominant rotifer taxa included Keratella cochlearis, Kellicottia longispina, Polyarthra vulgaris, Conochilus unicornis and a Synchaeta sp. Microplankton biomass was lowest in highly oligotrophic Toolik Lake (< 5 μgCl⁻¹ at the surface) and highest (up to 55 μCl⁻¹) in the most eutrophic lakes, experimentally fertilized lakes, and fertilized limnocorrals, consistent with bottom-up regulation of microplankton abundance.     

Nutrient cycling through phytoplankton, bacteria and protozoa, in selectively filtered Lake Vechten water

The breakdown of organic carbon of dead Synechococcus cell walls,added to selectively filtered Lake Vechten water, was not acceleratedby protozoa. During 4 weeks of incubation at 15°C no significantdecrease of total organic carbon was observed. However, heterotrophicnanoflagel-lates (HNAN) and ciliates strongly increased theremineralization of N and especially P, from both cell wallsand cell extract. Bacterioplankton growth did not result innet P mineralization but in P uptake. P was remineralized onlyin the presence of protozoan grazers. Both HNAN and ciliatesgrazed on bacteria, with ingestion rates estimated at 27–96bad HNAN^–1 h^–1 and 129 bact ciliate^–1 h^–1respectively. Grazers increased N mineralization too, althoughN was also mineralized in the absence of protozoa. The phytoplanktoncell walls yielded less P but more N remineralization than thecell extract. Thus, protozoa can strongly accelerate cyclingof specific nutrients through plankton. Nuclepore filters werefound to cause artificial DOC release during selective filtration.     

Chlorella-bearing ciliates dominate in an oligotrophic North Patagonian lake (Lake Pirehueico, Chile): abundance, biomass and symbiotic photosynthesis

1. Large mixotrophic ciliates ( Stentor araucanus , S. amethystinus and Ophrydium naumanni ) were a characteristic component of a temperate, oligotrophic lake in North Patagonia. During a 1-year study, the abundance, biomass and primary production of these large Chlorella -bearing ciliates were compared with those of the total plankton community.
2. Mixotrophic ciliates peaked in spring and from late summer to autumn, accounting for 1.6–43% (annual average: 16.3%) and 67–99% (annual average: 92%) of total ciliate abundance and biomass, respectively. Their contribution to total zooplankton biomass, including flagellates, rotifers, ciliates and crustaceans, was 14–76%, or 47% as an annual average. Endosymbiotic algae accounted for up to 25% of total autotrophic biomass (annual mean: 3.9%).
3. Maximum cell-specific photosynthetic rates of S. araucanus and S. amethystinus at light saturation varied between 80 and 4400 pg C ciliate^–1 h^–1 with high values during autumn and winter, and low values during summer. The depth-integrated rates of photosynthesis (0–40 m) of algal endosymbionts contributed 1–25% to total photosynthesis (annual mean: 6.5%).
4. A comparison of calculated ingestion rates with photosynthetic rates of Stentor indicates that photosynthate produced by endosymbionts generally exceeded heterotrophic food supply of Stentor during autumn and winter, but was much lower during summer, when food supply was high.
5. The mixotrophic ciliates represent an important 'link' between nanoplankton and higher trophic levels within the plankton community because of their high heterotrophic biomass and considerable contribution to total photosynthesis.     

The effect of small zooplankton on the microbial loop and edible algae during a cyanobacterial bloom

SUMMARY 1. We studied the effect of the small crustacean zooplankton on heterotrophic micro-organisms and edible phytoplankton in a eutrophic lake during a cyanobacterial bloom.
2. Small (15 L) enclosures were filled with natural or screened (100 μm) lake water and incubated for 5 days in the lake. Screening removed crustacean zooplankton but the initial density of rotifers and phytoplankton remained the same in control and removal treatments. Changes in the abundance and biomass of bacteria, autotrophic picoplankton (APP), heterotrophic nanoflagellates (HNF) and ciliates were measured daily.
3. The crustacean zooplankton, dominated by the small cladoceran Chydorus sphaericus , did not affect cyanobacteria, the main phytoplankton group during the experiment.
4. The removal of the crustacean zooplankton induced a higher abundance of ciliates and reduced that of the HNF, indicating the importance of ciliates in controlling HNF in this system.     

Biochemical composition of crustacean zooplankton and their grazing on phytoplankton and ciliated protozoans in a recently founded reservoir (Sahela, Morocco

In order to assess the impact of crustacean zooplankton on phytoplankton and protozoan ciliates in the Sahela reservoir under semi-arid climate, we conducted experiments during the period from July to December 1999 at the deepest point in the lake (15 m). Samplings and measurements were carried out in diffusion chambers submerged in situ over a period of 7 h without (control chambers) and with (experimental chambers) crustacean zooplankton. During these experiments, counts were conducted on phytoplankton and ciliates to determine the abundance and the mortality of these organisms due to zooplankton in each diffusion chambers at t = 0 and t = 7 h of incubation. The study showed that the growth rates of phytoplankton and ciliates populations varied between 0.02 and 0.05 h-1 and from 0.01 to 0.07 h-1, respectively. The mortality caused by zooplankton grazing fluctuated from 0.07 to 0.2 h-1 of phytoplankton and from 0.01 to 0.2 h-1 of ciliates. These mortalities were significantly and positively correlated with the growth rates (r = 0.8; p < 0.02; n = 9). Moreover, the heavy predation by the crustacean zooplankton was exerted on small-sized phytoplankton and ciliates and we demonstrated the relationships between protozoans and zooplankton for the transfer of matter and energy in aquatic food webs. Furthermore, the crustacean zooplankton metabolism was different, whether zooplankton was present in diffusion chambers or in the lake.     

Microplankton dynamics in a perennially ice-covered Antarctic lake – Lake Hoare

1. Temporal and spatial variation in planktonic abundance, biomass and composition were determined in Lake Hoare (McMurdo Dry Valleys, Antarctica) over two summer seasons (1996–97 and 1997–98). 2. Phototrophic nanoflagellates (PNAN) dominated planktonic biomass, with a mean monthly biomass ranging between 27.3 and 40.4 μg C L^?1. The deep chlorophyll maximum was mainly composed of cryptophytes (>87% of total PNAN biomass) and varied in depth between 6 and 12 m. 3. Maximum bacterial concentration was 11.8 × 10⁵ cells mL^?1. Bacterial abundance showed relatively little temporal variation, with the exception of a drop in numbers that occurred in late November of both years studied. 4. Ciliates were the most successful heterotrophic protozoan group, with a mean monthly biomass (1.2–3.2 μg C L^?1) being typically at least double that of heterotrophic nanoflagellate (HNAN) biomass (0.1–0.7 μg C L^?1). 5. Microbial processes within this lake appear to be dominated by bottom up control. The relative importance of allochthonous inputs into the lake (from the ice‐cover and stream flow) and autochthonous recycling (by microzooplankton regeneration) are considered. 6. Results from a horizontal transect indicate that the permanence of the main sample hole may have enhanced planktonic biomass over a relatively small spatial scale.     

The dynamics of heterotrophic nanoflagellates and bacterioplankton in a large ultra-oligotrophic Antarctic lake

The abundance of both heterotrophic nanoflagellates (HNAN) andbacterioplankton in a large (9km²) ultraoligotrophic Antarcticlake (Crooked Lake) were investigated from December 1992 untilNovember 1993. HNAN abundance peaked in spring, summer and autumn,falling to lowest numbers during the winter. Numbers rangedbetween 0 and 50.9x10⁴ l^–1. Bacterioplankton abundancewas highest during the late summer and then fell progressivelytowards winter and autumn (range 1.19–4.46x10⁶ l^–1)In contrast to numbers, mean cell volumes (MCV) of the bacteriareached their highest in spring, and consequently highest bacterialbiomass occurred at this time. MCV ranged between 0.052 and0.224µm³. Bacterial production measurements followingthe incorporation of [³H] thymidine into DNA and [¹⁴C] leucineinto protein using a doubling-labelling procedure were undertakenin January, June, August, October and November. Rates variedbetween 2.8 and 52 ng C l¹ h¹. On occasions, a significant differencein production rates based on the uptake of leucine and thymidinewas observed, suggesting unbalanced growth. Highest rates ofproduction coincided with times of high dissolved organic carbonlevels in the water column and lowest production with low levelsof DOC. HNAN grazing rates were measured by following the uptakeof fluorescently labelled bacteria and averaged 4.8 bacterialcells individual¹ day¹ at 2 and 4°C. Specific growth rates(h¹) ranged around 0.00070–0.00077 in both the field andlaboratory, giving doubling times of 37.3 and 41.0 days, respectively.These low rates of grazing and growth indicate that there isno adaptation to low temperatures in these freshwater protists.Based on these data, the gross production efficiency is 24%.HNAN removed between 0.1 and 9.7% of bacterial production perday.     

Evidence for predatory control of the invasive round goby

We coupled bioenergetics modeling with bottom trawl survey results to evaluate the capacity of piscivorous fish in eastern Lake Erie to exert predatory control of the invading population of round goby Neogobius melanostomus. In the offshore (>20 m deep) waters of eastern Lake Erie, burbot Lota lota is a native top predator, feeding on a suite of prey fishes. The round goby invaded eastern Lake Erie during the late 1990s, and round goby population size increased dramatically during 1999–2004. According to annual bottom trawl survey results, round goby abundance in offshore waters peaked in 2004, but then declined during 2004–2008. Coincidentally, round goby became an important component of burbot diet beginning in 2003. Using bottom trawling and gill netting, we estimated adult burbot abundance and age structure in eastern Lake Erie during 2007. Diet composition and energy density of eastern Lake Erie burbot were also determined during 2007. This information, along with estimates of burbot growth, burbot mortality, burbot water temperature regime, and energy densities of prey fish from the literature, were incorporated into a bioenergetics model application to estimate annual consumption of round goby by the adult burbot population. Results indicated that the adult burbot population in eastern Lake Erie annually consumed 1,361 metric tons of round goby. Based on the results of bottom trawling, we estimated the biomass of yearling and older round goby in offshore waters eastern Lake Erie during 2007–2008 to be 2,232 metric tons. Thus, the adult burbot population was feeding on round goby at an annual rate equal to 61% of the estimated round goby standing stock. We concluded that the burbot population had high potential to exert predatory control on round goby in offshore waters of eastern Lake Erie.