Diet and Prey Selection of Alewives in Lake Michigan: Seasonal, Depth, and Interannual Patterns

To evaluate the current diet of alewives Alosa pseudoharengus and interactions with their prey in light of recent changes in Lake Michigan, we determined the seasonal diet and prey selectivity of large (>100 mm total length) and small (<100 mm) alewives in southeastern Lake Michigan. Selectivity and diet were evaluated on a biomass basis for alewives collected near Muskegon, Michigan, during June, July−August, and October 1999–2001. Fish were sampled from three depth zones: shallow (15–25 m), transitional (35–55 m), and deep (65–90 m). Prey selectivity and diet patterns indicated that alewives had considerable flexibility in adjusting to prey availability, which varied by season, depth zone, and year. Although small copepods were an abundant prey item throughout the year and in all depth zones, they were mainly important in the diet (large and small alewives) in June and at the shallow stations, where many of the other prey types were not available. Despite declining numbers, Diporeia continued to be important for large alewives in spring, particularly at the transitional and deep stations, where their biomass was many times higher than that of other prey. During summer, large alewives selected either Bythotrephes longimanus or Mysis relicta in all depth zones and years. The diet of large alewives consisted mainly of Mysis in July 1999 and August 2001, whereas in August 2000 mainly Bosmina were eaten. During October, Mysis and Bythotrephes, along with large zooplankters (Daphnia spp. and large calanoid copepods), were selected and were most important in the diet of large alewives. In contrast, only the large zooplankton were selected and were important prey for the small alewives in fall. Annual, seasonal, and depth differences in prey biomass as well as differences in alewife size all influenced diet and selectivity patterns.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141716/1/tafs1068.pd

Evidence of hypoxic foraging forays by yellow perch ( Perca flavescens ) and potential consequences for prey consumption

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91146/1/FWB_2753_sm_fS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/91146/2/j.1365-2427.2012.02753.x.pd

Corrigendum to “Recent changes in primary production and phytoplankton in the offshore region of southeastern Lake Michigan” [J. Great Lakes Res. 36 (Supplement 3) (2010) 20–29]

The authors regret that there is an error on the labels of two figures that were published in the paper referenced above. For Figs. 5b, c, and d and 7b and c the y-axes have the wrong labels. The following are the correct y-axis labels: Fig. 5b — the y-axis should range from 0 to 5, Fig. 5c — the y-axis should range from 0 to 2, Fig. 5d — the y-axis label should range from 0 to 3, Fig. 7b — the y-axis should range from 0 to 40, and for Fig. 7c — the y-axis should range from 0 to 50

Corrigendum to “Recent changes in primary production and phytoplankton in the offshore region of southeastern Lake Michigan” [J. Great Lakes Res. 36 (Supplement 3) (2010) 20–29]

The authors regret that there is an error on the labels of two figures that were published in the paper referenced above. For Figs. 5b, c, and d and 7b and c the y-axes have the wrong labels. The following are the correct y-axis labels: Fig. 5b — the y-axis should range from 0 to 5, Fig. 5c — the y-axis should range from 0 to 2, Fig. 5d — the y-axis label should range from 0 to 3, Fig. 7b — the y-axis should range from 0 to 40, and for Fig. 7c — the y-axis should range from 0 to 50

Anatomy of the recurrent coastal sediment plume in Lake Michigan and its impacts on light climate, nutrients, and plankton

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94624/1/jgrc9664.pd

Alewife planktivory controls the abundance of two invasive predatory cladocerans in Lake Michigan

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74873/1/j.1365-2427.2007.01728.x.pd

Radioecology of benthic fishes off Oregon, U.S.A.

Gamma-emitting radionuclides were found in benthic fishes from depths of 50-280O m off the Oregon coast from 1964-1971. 65Zn, 60Co, 54Mn, 144Ce, 137Cs and 40K were present. Zinc-65, originating mainly from the nuclear reactors on the Columbia River, was the predominant artifically-induced radionuclide. Levels of 6Zn per g and specific activities of 65Zn decreased markedly in several species of fishes between 1965 and 1971 because of the shutdown of reactors. This decrease was greater for small than large Lyopsetta exilis during 19 70-1971. Specific activities decreased with increasing depth, both for individual species inhabiting broad depth ranges and for different species inhabiting different depths. Specific activities of 65Zn were inversely related to body size for L. exilis and Sebastolobus. Other variations of 65Zn were related to trophic position. Fishes that preyed on low trophic level pelagic animals had higher specific activities than fishes that preyed on benthic invertebrates. Such pelagic feeders may play an important role in accelerating the transport of some radionuclides or elements to the sea floor.Keywords: Marine radioecology, benthic fishe

Influence of invasive quagga mussels, phosphorus loads, and climate on spatial and temporal patterns of productivity in Lake Michigan: A biophysical modeling study

We applied a three‐dimensional biophysical model to Lake Michigan for the years 2000, 2005, and 2010 to consider the mechanisms controlling spatial and temporal patterns of phytoplankton abundance (chlorophyll a) and lake‐wide productivity. Model skill was assessed by comparison to satellite‐derived Chl a and field‐measured water quality variables. We evaluated model sensitivity to scenarios of varying mussel filter feeding intensity, tributary phosphorus loads, and warm vs. cool winter‐spring climate scenarios. During the winter‐spring phytoplankton bloom, spatial patterns of Chl a were controlled by variables that influenced surface mixed layer depth: deep mixing reduced net phytoplankton growth through light limitation and by exposing the full water column to mussel filter feeding. Onset of summer and winter stratification promoted higher surface Chl a initially by increasing mean light exposure and by separating the euphotic zone from mussels. During the summer stratified period, areas of relatively high Chl a were associated with coastal plumes influenced by tributary‐derived nutrients and coastal upwelling‐downwelling. While mussels influenced spatial and temporal distribution of Chl a, lake‐wide, annual mean primary production was more sensitive to phosphorus and warm/cool meteorology scenarios than to mussel filter feeding scenarios. Although Chl a and primary production declined over the quagga mussel invasion, our results suggest that increased nutrient loads would increase lake‐wide productivity even in the presence of mussels; however, altered spatial and temporal patterns of productivity caused by mussel filter feeding would likely persist.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139984/1/lno10595-sup-0001-suppinfo.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139984/2/lno10595.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139984/3/lno10595_am.pd

Spatial distribution, biomass and population dynamics of Mysis relicta in Lake Michigan

The abundance, biomass, and life history traits of Mysis relicta were evaluated in the spring, summer, and autumn of 2000 at 8 nearshore (45 m) and 8 offshore (75–110 m) stations throughout central and southern Lake Michigan. Abundance was also evaluated on a smaller scale during June 2000 at 4 nearshore and 4 offshore stations in southeastern Lake Michigan. For large-scale sampling, the abundance of M. relicta did not differ among locations in the spring. In the summer and autumn the abundance of M. relicta was similar among offshore stations with the exception of one station each season; for nearshore stations, abundance was generally highest off Pentwater, Michigan. The abundance of mysids was not consistently high for central or southern basin sites, although overall biomass was higher in the southern basin each season. Abundance of Mysis was positively correlated with bottom depth, but not with bottom water temperature, surface water temperature, or mean chlorophyll concentration. Within the smaller region in southeast Lake Michigan, the abundance of M. relicta differed among locations for both nearshore and offshore stations. Brood size and size of reproductive females did not differ among lake wide locations, but the proportion of females with broods and the size distribution of M. relicta did.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42900/1/10750_2004_Article_5266883.pd

The Changing Face of Winter: Lessons and Questions From the Laurentian Great Lakes

Among its many impacts, climate warming is leading to increasing winter air temperatures, decreasing ice cover extent, and changing winter precipitation patterns over the Laurentian Great Lakes and their watershed. Understanding and predicting the consequences of these changes is impeded by a shortage of winter-period studies on most aspects of Great Lake limnology. In this review, we summarize what is known about the Great Lakes during their 3–6 months of winter and identify key open questions about the physics, chemistry, and biology of the Laurentian Great Lakes and other large, seasonally frozen lakes. Existing studies show that winter conditions have important effects on physical, biogeochemical, and biological processes, not only during winter but in subsequent seasons as well. Ice cover, the extent of which fluctuates dramatically among years and the five lakes, emerges as a key variable that controls many aspects of the functioning of the Great Lakes ecosystem. Studies on the properties and formation of Great Lakes ice, its effect on vertical and horizontal mixing, light conditions, and biota, along with winter measurements of fundamental state and rate parameters in the lakes and their watersheds are needed to close the winter knowledge gap. Overcoming the formidable logistical challenges of winter research on these large and dynamic ecosystems may require investment in new, specialized research infrastructure. Perhaps more importantly, it will demand broader recognition of the value of such work and collaboration between physicists, geochemists, and biologists working on the world\u27s seasonally freezing lakes and seas