Cornell Biological Field Station

Bridgeport, NY, United States

Cornell Biological Field Station

Bridgeport, NY, United States

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Watkins J.,Cornell Biological Field Station
Aquatic Ecosystem Health and Management | Year: 2010

Satellite-based sensors provide synoptic measurements of surface parameters useful in detecting physical and biological conditions of the Great Lakes. Satellite surface temperature measurements using infrared spectra are compatible with buoy measurements and the time series now covers more than two decades in length. This time-series tracks seasonal warming patterns and localized upwelling events. The use of visible spectra for remote sensing of water clarity and particle composition is improving with new algorithms to separate chlorophyll-a, inorganic particles, and dissolved organic matter. The use of satellites to measure these variables holds promise for future quantification of phytoplankton production, calcite precipitation (whiting), and suspended sediment from rivers and resuspension events. Satellite imagery has also been useful for interpreting ship-collected data such as those associated with the bi-national Lake Ontario Lower Foodweb Assessment (LOLA) in 2003. © 2010 AEHMS.


Wang R.W.,Cornell Biological Field Station | Rudstam L.G.,Cornell Biological Field Station | Brooking T.E.,Cornell Biological Field Station | Snyder D.J.,50 Hiawatha Boulevard | And 2 more authors.
Lake and Reservoir Management | Year: 2010

The annual spring clear water phase (May-June) in Onondaga Lake, New York, unexpectedly disappeared in 2003 following several years of phosphorus and ammonia loading reductions at the Metropolitan Syracuse Wastewater Treatment Facility (Metro). Mean chlorophyll a concentration during May-June was higher from 2003 to 2007 than from 1990 to 2002, with mean Secchi disk depths <2 m. Large zooplankton (Daphnia sp.) were abundant during April-June before 2003 but were rare from 2003 to 2007, while abundance of small zooplankton (Bosmina longirostris) increased. Alewife (Alosa pseudoharengus) catches from electrofishing surveys dramatically increased in 2003, and hydroacoustic surveys estimated the alewife population to be between 1600 and 2300 fish/ha in spring 2005-2007. The alewife population in 2005 was dominated by a strong 2002 year class. Increasing biomass of the 2002 year class coincided with the timing of the shift from large to small zooplankton in late summer of 2002. This indicates that the strong 2002 alewife year class initiated a classic trophic cascade in Onondaga Lake, causing the decline and continuing low abundance of Daphnia sp. and the disappearance of the spring clear water phase. The increase in alewife may have been associated with decreasing ammonia concentrations following improvement to Metro. Unionized ammonia has been below levels considered toxic to nonsalmonid fish species since 1999, and the ammonia concentration continues to decrease in the lake. Thus, reductions in nutrient loading can lead to unanticipated food web effects causing decreases rather the expected increases in water clarity in the spring-early summer period. © 2010 Copyright by the North American Lake Management Society.


Watkins J.M.,Cornell Biological Field Station | Rudstam L.G.,Cornell Biological Field Station | Crabtree D.L.,The Nature Conservancy | Walsh M.G.,U.S. Geological Survey
Journal of Great Lakes Research | Year: 2013

Benthic monitoring by USGS off the southern shore of Lake Ontario from October 1993 to October 1995 provides a detailed view of the early stages of the decline of the native amphipod Diporeia. A loss of the 1994 and 1995. year classes of Diporeia preceded the disappearance of the native amphipod at sites near Oswego and Rochester at depths from 55 to 130. m. In succeeding years, Diporeia populations continued to decline in Lake Ontario and were nearly extirpated by 2008. Explanations for Diporeia's decline in the Great Lakes include several hypotheses often linked to the introduction and expansion of exotic zebra and quagga mussels (Dreissena sp.). We compare the timeline of the Diporeia decline in Lake Ontario with trends in two sources of organic matter to the sediments - spring diatom blooms and late summer whiting events. The 1994-95 decline of Diporeia coincided with localized dreissenid effects on phytoplankton in the nearshore and a year (April 1994 to May 1995) of decreased flux of organic carbon recorded by sediment traps moored offshore of Oswego. Later declines of profundal (> 90. m) Diporeia populations in 2003 were poorly associated with trends in spring algal blooms and late summer whiting events. © 2013 Elsevier B.V.


Johannsson O.E.,Canadian Department of Fisheries and Oceans | Bowen K.L.,Canadian Department of Fisheries and Oceans | Holeck K.T.,Cornell Biological Field Station | Walsh M.G.,U.S. Geological Survey
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2011

We investigated population responses of Mysis to ecosystem changes induced by invasion of dreissenids and predatory cladocerans, Cercopagis and Bythotrephes. Lake productivity declined as dreissenids invaded the offshore region. Whole-lake mysid biomass was compared before (early 1990s) and after (2002-2007) the invasion period; it declined 40%- 45%. Abundance of young mysids and presence of a summer cohort increased with summer, epilmnetic, nighttime zooplankton biomass (i.e., food biomass index). Cercopagis + Bythotrephes biomass was negatively correlated with this index, implicating them in the mysid decline. Eggs per gravid female increased with autumn, total-water-column zooplankton biomass, reflecting the greater use of hypolimnetic waters by adults. Reproductive success was below replacement during the period 2002-2005. First-year mysid growth rate was maintained while population abundance declined, suggesting selection for individuals that feed effectively at low food concentrations. Mortality rates in the first and second years were dependent on cohort density, indicating that competition for food limited abundance in the first 2 years. Fish predation indices (smelt and alewife combined) were correlated positively with mortality rates and negatively with abundance in the third year. Thus, mysids cannot support as many fish in invaded compared with non-invaded lakes. They may also not be a stable food resource; unusual cohort losses occurred in some years.


Stapanian M.A.,U.S. Geological Survey | Paragamian V.L.,885 W. Kathleen Avenue | Madenjian C.P.,U.S. Geological Survey | Jackson J.R.,Cornell Biological Field Station | And 3 more authors.
Fish and Fisheries | Year: 2010

Although burbot (Lota lota Gadidae) are widespread and abundant throughout much of their natural range, there are many populations that have been extirpated, endangered or are in serious decline. Due in part to the species' lack of popularity as a game and commercial fish, few regions consider burbot in management plans. We review the worldwide population status of burbot and synthesize reasons why some burbot populations are endangered or declining, some burbot populations have recovered and some burbot populations do not recover despite management measures. Burbot have been extirpated in much of Western Europe and the United Kingdom and are threatened or endangered in much of North America and Eurasia. Pollution and habitat change, particularly the effects of dams, appear to be the main causes for declines in riverine burbot populations. Pollution and the adverse effects of invasive species appear to be the main reasons for declines in lacustrine populations. Warmer water temperatures, due either to discharge from dams or climate change, have been noted in declining burbot populations at the southern extent of their range. Currently, fishing pressure does not appear to be limiting burbot populations world-wide. We suggest mitigation measures for burbot population recovery, particularly those impacted by dams and invasive species. Published 2010. This article is an US Government work and is in the public domain in the USA.


Lantry B.F.,U.S. Geological Survey | Gumtow C.F.,U.S. Geological Survey | Walsh M.G.,U.S. Geological Survey | Weidel B.C.,U.S. Geological Survey | And 2 more authors.
Journal of Great Lakes Research | Year: 2012

We investigated the seasonal occurrence of Hemimysis anomala in the diets of fish that prey on macroinvertebrates at two sites with established Hemimysis populations east of Oswego, NY, during 2009-2010. In 2009, we examined 320 stomachs from 10 species and found Hemimysis only in alewife (Alosa pseudoharengus), rockbass (Ambloplites rupestris), and yellow perch (Perca flavescens). Of those species, alewife consumed Hemimysis most frequently and it represented a greater proportion of their diets. During 2009, the dry weight composition of Hemimysis in alewife diets varied seasonally between < 1% in June, 5% in July, 98.5% in August, and 18.8% in September. In contrast, we examined 667 stomachs from 15 species in 2010 and observed Hemimysis in only one alewife and two rockbass stomachs. For alewife from September 2009, we found no relationship between predator size and the number of Hemimysis consumed, or between the presence of Hemimysis in fish diets and the presence of other diet taxa or diet diversity. Fish diets collected as bycatch from other assessments revealed large numbers of Hemimysis in fishes that had not previously been observed consuming Hemimysis in Lake Ontario, including cisco (Coregonus artedi) and white perch (Morone americana). Our results indicate Hemimysis consumption by nearshore fish can be high, but that it is variable across seasons and years, and may be most prevalent in fish that feed up in the water column, at or near dark, and have the ability to consume swift moving prey like Mysis diluviana or small fish. © 2011 International Association for Great Lakes Research.


Watkins J.M.,Cornell Biological Field Station | Rudstam L.G.,Cornell Biological Field Station | Mills E.L.,Cornell Biological Field Station | Teece M.A.,New York University
Journal of Great Lakes Research | Year: 2012

Populations of the benthic amphipod Diporeia spp. have sharply declined since the early 1990s in all North America's Great Lakes except Lake Superior. The onset and continued decline coincides with the invasion of these lakes by zebra (Dreissena polymorpha) and quagga (Dreissena rostriformis bugensis) mussels and the spread of quagga mussels to deep habitats. The six deepest Finger Lakes of central New York (Seneca, Cayuga, Skaneateles, Canandaigua, Keuka, and Owasco) have historically been Diporeia habitat and have had dreissenids for more than a decade. These lakes represent a wide range of trophic state, maximum depth, and dreissenid invasion history. We hypothesized that Diporeia abundance would be negatively impacted by dreissenid mussel expansion in the Finger Lakes. During 2006-2010, we sampled Diporeia and mussel populations in these six lakes. Diporeia was present in all six lakes, and was abundant (2000/m 2) in Owasco Lake that has only zebra mussels and in Cayuga and Seneca Lakes that have had zebra and quagga mussels since 1994. Diporeia abundance was lowest (1000/m 2) in Skaneateles, Canandaigua, and Keuka Lakes where quagga mussels have recently expanded. Productivity indicators explained much of the variability of Diporeia abundance. The persistence of Diporeia with quagga mussels in these lakes may be because of available alternative food resources. Fatty acid tracers indicate that Diporeia from Owasco Lake, the lake without quagga mussels, utilize diatoms, but Diporeia from Cayuga Lake that coexist with abundant quagga mussels also use food resources associated with terrestrial detritus that cannot be intercepted by dreissenids. © 2012 International Association for Great Lakes Research.


Karatayev A.Y.,Buffalo State College | Burlakova L.E.,Buffalo State College | Burlakova L.E.,State University of New York at Buffalo | Mastitsky S.E.,Buffalo State College | And 3 more authors.
Journal of Shellfish Research | Year: 2011

Examining congeners can help identify critical differences between species that affect invasion and spread. We examined Dreissenapolymorpha (zebra mussel) and Dreissena rostriformis bugensis (quagga mussel), which are important invaders in freshwater and share general ecological characteristics, to determine whether they had similar rates of invasion at different spatial scales (global, regional, local, and individual water bodies) from the time of first introduction to the present. We also contrasted differences in ecological and population characteristics that could influence speed of spread. Although D. polymorpha and D. r. bugensis are relatives and share a common native habitat, morphology, lifestyle, life history, and dispersal potential, D. polymorpha was found to be a better invader than D. r. bugensis at most spatial scales throughout their invasion history. Spread at the regional scale in North America was the same for both species, but the initial rate of invasion by zebra mussels far outpaced the spread of quagga mussels both in the United States and in Europe. The estimated lag time between initial introduction and maximal population size is 5 times shorter for D. polymorpha than for D. r. bugensis, which may be an important factor affecting the speed with which this species can spread. Differences in population dynamics may facilitate the increased rates of spread of D. polymorpha relative to D. r. bugensis, especially at smaller spatial scales.


Manning N.F.,University of Toledo | Bossenbroek J.M.,University of Toledo | Mayer C.M.,University of Toledo | Bunnell D.B.,U.S. Geological Survey | And 3 more authors.
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2014

We sought to quantify the possible population-level influence of sediment plumes and algal blooms on yellow perch (Perca flavescens), a visual predator found in systems with dynamic water clarity. We used an individual-based model (IBM), which allowed us to include variance in water clarity and the distribution of individual sizes. Our IBM was built with laboratory data showing that larval yellow perch feeding rates increased slightly as sediment turbidity level increased, but that both larval and juvenile yellow perch feeding rates decreased as phytoplankton level increased. Our IBM explained a majority of the variance in yellow perch length in data from the western and central basins of Lake Erie and Oneida Lake, with R2 values ranging from 0.611 to 0.742. Starvation mortality was size dependent, as the greatest daily mortality rates in each simulation occurred within days of each other. Our model showed that turbidity-dependent consumption rates and temperature are key components in determining growth and starvation mortality of age-0 yellow perch, linking fish production to land-based processes that influence water clarity. These results suggest the timing and persistence of sediment plumes and algal blooms can drastically alter the growth potential and starvation mortality of a yellow perch cohort. © 2014 Can. J. Fish. Aquat. Sci. All rights reserved.


Kocovsky P.M.,U.S. Geological Survey | Rudstam L.G.,Cornell Biological Field Station | Yule D.L.,U.S. Geological Survey | Warner D.M.,U.S. Geological Survey | And 5 more authors.
Journal of Great Lakes Research | Year: 2013

Standardized methods of data collection and analysis ensure quality and facilitate comparisons among systems. We evaluated the importance of three recommendations from the Standard Operating Procedure for hydroacoustics in the Laurentian Great Lakes (GLSOP) on density estimates of target species: noise subtraction; setting volume backscattering strength (Sv) thresholds from user-defined minimum target strength (TS) of interest (TS-based Sv threshold); and calculations of an index for multiple targets (Nv index) to identify and remove biased TS values. Eliminating noise had the predictable effect of decreasing density estimates in most lakes. Using the TS-based Sv threshold decreased fish densities in the middle and lower layers in the deepest lakes with abundant invertebrates (e.g., Mysis diluviana). Correcting for biased in situ TS increased measured density up to 86% in the shallower lakes, which had the highest fish densities. The current recommendations by the GLSOP significantly influence acoustic density estimates, but the degree of importance is lake dependent. Applying GLSOP recommendations, whether in the Laurentian Great Lakes or elsewhere, will improve our ability to compare results among lakes. We recommend further development of standards, including minimum TS and analytical cell size, for reducing the effect of biased in situ TS on density estimates. © 2013.

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