Changes in the Nearshore and Offshore Zooplankton Communities in Lake Ontario: 1981–88

1991 ◽  
Vol 48 (8) ◽  
pp. 1546-1557 ◽  
Author(s):  
Ora E. Johannsson ◽  
Edward L. Mills ◽  
Robert O'Gorman
Keyword(s):  
Lake Ontario ◽  
Zooplankton Abundance ◽  
Alosa Pseudoharengus ◽  
Catch Per Unit Effort ◽  
Eastern Basin ◽  
Cladoceran Species ◽  
Large Populations ◽  
Daphnia Galeata Mendotae ◽  
And Shifts ◽  
Zooplankton Communities

We examined trends and factors influencing changes in nearshore and offshore zooplankton abundance and composition in Lake Ontario between 1981 and 1988. In the nearshore (southshore and eastern basin), zooplankton abundance decreased and shifts occurred in the relative abundances of Bosmina longirostris and Daphnia retrocurva (eastern basin) and Daphnia retrocurva and Daphnia galeata mendotae (southshore). These changes could have resulted from increased vertebrate predation or reduced food resources which intensified the effects of predation. In the offshore, the first appearance (FA) of the larger, less common cladoceran species occurred earlier in the season as of 1985. FA was correlated with cumulative epilimnetic temperature (CET) and the catch per unit effort (CPUE) of alewife (Alosa pseudoharengus) [Formula: see text] caught in U.S. waters in the spring. In 1987, when CET was high and CPUE of alewife [Formula: see text] was low, large populations of these cladocerans developed in June and July. Bythotrephes cederstroemi, a recent invader in the Great Lakes, was abundant only in 1987 when the CPUE of alewife was lowest. Changes in zooplankton abundance, development, and composition along the nearshore–offshore gradient reflected effects of temperature, habitat, and planktivory on the community.

Chemical and Biological Changes in Nelson Lake, Ontario Following Experimental Elevation of Lake pH

1977 ◽  
Vol 12 (1) ◽  
pp. 213-232 ◽  
Author(s):  
N.D. Yan ◽  
W.A. Scheider ◽  
P.J. Dillon
Keyword(s):  
Heavy Metal ◽  
Lake Ontario ◽  
Background Concentrations ◽  
Precambrian Shield ◽  
Metal Levels ◽  
Zooplankton Communities ◽  
Shield Lakes

Abstract Intensive studies of Nelson Lake, a Sudbury area lake of intermediate pH ~5.7), were begun in 1975. The chemistry of the lake was typical of that of most PreCambrian Shield lakes except that low alkalinities and high sulphate concentrations were observed along with elevated heavy metal levels. After raising the pH of Nelson Lake to 6.4 by addition of Ca(OH)2 and CaCO3, the metals were reduced to background concentrations. Phytoplankton and Zooplankton communities, which at pH of 5.7 were typical of PreCambrian lakes, were not affected by the experimental elevation of lake pH.

Changes in the crustacean communities of Lakes Michigan, Huron, and Erie following the invasion of the predatory cladoceran Bythotrephes longimanus

2004 ◽  
Vol 61 (11) ◽  
pp. 2111-2125 ◽  
Author(s):  
Richard P Barbiero ◽  
Marc L Tuchman
Keyword(s):  
Zooplankton Community ◽  
Crustacean Zooplankton ◽  
Bythotrephes Longimanus ◽  
Zooplankton Community Structure ◽  
Cladoceran Species ◽  
Invertebrate Predators ◽  
Predatory Cladoceran ◽  
Leptodora Kindti ◽  
Escape Responses ◽  
Zooplankton Communities

The crustacean zooplankton communities in Lakes Michigan and Huron and the central and eastern basins of Lake Erie have shown substantial, persistent changes since the invasion of the predatory cladoceran Bythotrephes in the mid-1980s. A number of cladoceran species have declined dramatically since the invasion, including Eubosmina coregoni, Holopedium gibberum, Daphnia retrocurva, Daphnia pulicaria, and Leptodora kindti, and overall species richness has decreased as a result. Copepods have been relatively unaffected, with the notable exception of Meso cyclops edax, which has virtually disappeared from the lakes. These species shifts have for the most part been consistent and equally pronounced across all three lakes. Responses of crustacean species to the Bythotrephes invasion do not appear to be solely a consequence of size, and it is likely that other factors, e.g., morphology, vertical distribution, or escape responses, are important determinants of vulnerability to predation. Our results indicate that invertebrate predators in general, and invasive ones in particular, can have pronounced, lasting effects on zooplankton community structure.

Planktivory by alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) on microcrustacean zooplankton and dreissenid (Bivalvia: Dreissenidae) veligers in southern Lake Ontario

1995 ◽  
Vol 52 (5) ◽  
pp. 925-935 ◽  
Author(s):  
Edward L. Mills ◽  
Connie Adams ◽  
Robert O'Gorman ◽  
Randall W. Owens ◽  
Edward F. Roseman
Keyword(s):  
Laboratory Experiments ◽  
Lake Ontario ◽  
Osmerus Mordax ◽  
Field Observations ◽  
Alosa Pseudoharengus ◽  
Rainbow Smelt ◽  
Consumption Rates ◽  
South Shore ◽  
Young Of The Year ◽  
Veliger Larvae

The objective of this study was to describe the diet of young-of-the-year and adult alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) in nearshore waters coincident with the colonization of Lake Ontario by Dreissena. Laboratory experiments and field observations indicated that alewife and rainbow smelt consumed dreissenid veligers and that the veligers remained intact and identifiable in the digestive tract for several hours. Dreissenid larvae were found in field-caught alewife and rainbow smelt in August 1992, even though veliger densities were low (<0.1/L). Zooplankton dominated the diet of all fish and veliger larvae were <0.1% of the biomass of prey eaten by these fish. Density of veligers and the distribution of settled dreissenids declined from west to east along the south shore of Lake Ontario. Based on veliger consumption rates we measured and the abundance of veligers and planktivores, we conclude that planktivory by alewife and smelt in the nearshore waters of Lake Ontario did not substantially reduce the number of veligers during 1991–1993. However, our results indicate that if the density of veligers in Lake Ontario decreases, and if planktivores remain abundant, planktivory on veliger populations could be significant.

Invasion of Lake Erie Offshore Sediments by Dreissena, and Its Ecological Implications

1993 ◽  
Vol 50 (11) ◽  
pp. 2298-2304 ◽  
Author(s):  
R. Dermott ◽  
M. Munawar
Keyword(s):  
Zebra Mussel ◽  
Dreissena Polymorpha ◽  
Lake Erie ◽  
Quagga Mussel ◽  
Central Basin ◽  
Eastern Basin ◽  
Fine Sediments ◽  
Ecological Implications ◽  
Large Populations ◽  
Hard Substrates

Large populations of the exotic rounded (noncarinate) shelled mussel of the genus Dreissena were found to exist on soft sediments collected throughout the central and eastern basins of Lake Erie during July and August 1992. Two different phenotypes were present on fine sediments (<150 μm) in the eastern basin. An elongated white morph was common on the profundal sediments beyond 40 m depth, while the "quagga" mussel was common on sand and sandy silt at depths between 10 and 30 m. Together with the carinated zebra mussel Dreissena polymorpha, which is very abundant on hard substrates in the sublittoral region, at least 80% of Lake Erie's bottom sediments have been invaded by Dreissena. Only that region of the central basin (near Cleveland) which undergoes periodic summer anoxia was not inhabited by this genus.

Environmental drivers of a decline in a coastal zooplankton community

2021 ◽  
Author(s):  
Seòna R Wells ◽  
Eileen Bresnan ◽  
Kathryn Cook ◽  
Dafne Eerkes-Medrano ◽  
Margarita Machairopoulou ◽  
...  
Keyword(s):  
Zooplankton Community ◽  
Water Masses ◽  
Environmental Drivers ◽  
High Temporal Resolution ◽  
Monitoring Site ◽  
Zooplankton Abundance ◽  
Offshore Water ◽  
Additive Mixed Models ◽  
Zooplankton Communities

Abstract Major changes in North Atlantic zooplankton communities in recent decades have been linked to climate change but the roles of environmental drivers are often complex. High temporal resolution data is required to disentangle the natural seasonal drivers from additional sources of variability in highly heterogeneous marine systems. Here, physical and plankton abundance data spanning 2003–2017 from a weekly long-term monitoring site on the west coast of Scotland were used to investigate the cause of an increasing decline to approximately -80± 5% in annual average total zooplankton abundance from 2011 to 2017. Generalized additive mixed models (GAMMs), with an autoregressive correlation structure, were used to examine seasonal and inter-annual trends in zooplankton abundance and their relationship with environmental variables. Substantial declines were detected across all dominant taxa, with ∼ 30–70% of the declines in abundance explained by a concurrent negative trend in salinity, alongside the seasonal cycle, with the additional significance of food availability found for some taxa. Temperature was found to drive seasonal variation but not the long-term trends in the zooplankton community. The reduction in salinity had the largest effect on several important taxa. Salinity changes could partly be explained by locally higher freshwater run-off driven by precipitation as well as potential links to changes in offshore water masses. The results highlight that changes in salinity, caused by either freshwater input (expected from climate predictions) or fresher offshore water masses, may adversely impact coastal zooplankton communities and the predators that depend on them.

From Catastrophe to Recovery: Stories of Fishery Management Success

2019 ◽  
Keyword(s):  
Food Web ◽  
Fishery Management ◽  
Conservation Status ◽  
Lake Ontario ◽  
Water Clarity ◽  
Lessons Learned ◽  
Alosa Pseudoharengus ◽  
Nutrient Inputs ◽  
Rainbow Smelt ◽  
Trawl Surveys

<i>Abstract</i>.—Fish population recoveries can result from ecosystem change in the absence of targeted restoration actions. In Lake Ontario, native Deepwater Sculpin <i>Myoxocephalus thompsonii</i> were common in the late 1800s, but by the mid-1900s the species was possibly extirpated. During this period, mineral nutrient inputs increased and piscivore abundance declined, which increased the abundance of the nonnative planktivores Alewife <i>Alosa pseudoharengus</i> and Rainbow Smelt <i>Osmerus mordax</i>. Deepwater Sculpin larvae are pelagic and vulnerable to predation by planktivores. Annual bottom trawl surveys did not capture Deepwater Sculpin from 1978 to 1995 (<i>n</i> = 6,666 tows) despite sampling appropriate habitat (trawl depths: 7–170 m). The absence of observations during this time resulted in an elevated conservation status for the species, but no restoration actions were initiated. In 1996, three individuals were caught in bottom trawls, the first observed since 1972. Since then, their abundance has increased, and in 2017, they were the second most abundant Lake Ontario prey fish. The food-web changes that occurred from 1970 through the 1990s contributed to this recovery. Alewife and Rainbow Smelt abundance declined during this period due to predation by stocked salmonids and legislation that reduced nutrient inputs and food web productivity. In the 1990s, proliferation of nonnative, filter-feeding dreissenid mussels dramatically increased water clarity. As light penetration increased, the early-spring depth distribution of Alewife and Rainbow Smelt shifted deeper, away from larval Deepwater Sculpin habitat. The intentional and unintentional changes that occurred in Lake Ontario were not targeted at Deepwater Sculpin restoration but resulted in conditions that favored the species’ recovery. While standard surveys documented the recovery, more diverse information (e.g., observations in deep habitats and early-life stages) would have improved our understanding of why the species recovered when it did. Annual Lake Ontario trawl surveys have collaboratively expanded their spatial extent and diversified habitat sampled, based on lessons learned from the Deepwater Sculpin recovery.

Mysid and fish zooplanktivory in Lake Ontario: quantification of direct and indirect effects

2006 ◽  
Vol 63 (12) ◽  
pp. 2734-2747 ◽  
Author(s):  
Gideon Gal ◽  
Lars G Rudstam ◽  
Edward L Mills ◽  
Jana R Lantry ◽  
Ora E Johannsson ◽  
...  
Keyword(s):  
Indirect Effects ◽  
Lake Ontario ◽  
Fish Feed ◽  
Osmerus Mordax ◽  
Alosa Pseudoharengus ◽  
Rainbow Smelt ◽  
Mysis Relicta ◽  
Consumption Rates ◽  
Positive Effect ◽  
Potential Rate

Mysis relicta and planktivorous fish feed on zooplankton in Lake Ontario and form a trophic triangle that includes intraguild predation by fish on mysids. Thus, fish affect zooplankton both directly and indirectly. To evaluate the importance of alewife (Alosa pseudoharengus), rainbow smelt (Osmerus mordax), and mysids as zooplanktivores in Lake Ontario, we measured abundances and distributions, assessed diets, and computed mysid and fish consumption rates based on bioenergetics models. We further estimated indirect effects by comparing clearance rates given observed and potential mysid distributions. Estimated consumption rates varied widely with season and water depth and ranged between 2.6 × 10–3 and 1.3 g·m–2·day–1 for mysids and between 1.4 × 10–3 and 0.5 g·m–2·day–1 for fish, representing a daily removal of zooplankton of up to 10.2%·day–1 and 2.0%·day–1 by mysids and fish, respectively. Mysid planktivory exceeded fish planktivory in May and August, but fish planktivory dominated in October. Estimated mysid planktivory rates were 2- to 90-fold lower than the potential rate if mysids moved to temperatures that maximized their predation rates, suggesting an indirect positive effect of fish on zooplankton.

Piscivority in a Land-Locked Alewife (Alosa pseudoharengus) Population

1980 ◽  
Vol 37 (8) ◽  
pp. 1314-1317 ◽  
Author(s):  
Christopher C. Kohler ◽  
John J. Ney
Keyword(s):  
Great Lakes ◽  
Larval Fish ◽  
Early Summer ◽  
Zooplankton Abundance ◽  
Alosa Pseudoharengus ◽  
Zooplankton Density ◽  
Forage Species ◽  
Dietary Component ◽  
Fish Ingestion ◽  
Precipitous Decline

Larval fish were a frequent dietary component of alewives (Alosa pseudoharengus) from Claytor Lake, Virginia, USA. Alewives consumed the young of four game and two forage species (maximum 26 mm total length (TL)). Alewife piscivority appeared to be at least partially nocturnal and was more prominent in littoral than in limnetic areas. Predator and prey lengths were positively correlated, although morphological limits on larval fish ingestion by alewives were not severe. Peak occurrence (40–70%, June 1978) of larval fish in alewife stomachs coincided with a precipitous decline in zooplankton density. Zooplankton abundance was higher in early summer 1979, when alewife piscivority was less common. Our findings support the hypothesis that alewife piscivority could have contributed to the collapse of Great Lakes resident fish populations following alewife establishment. Alewife piscivority should be considered in risk–benefit evaluations prior to introducing alewife as a pelagic forage species.Key words: alewife, Alosa pseudoharengus; feeding ecology, larval fish, Great Lakes fisheries, forage introductions

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