Impacts of Adfluvial Fish on the Ecology of Two Great Lakes Tributaries

Anadromous and adfluvial fish can transport high concentrations of nutrients and energy into streams during spawning runs. While the ecological effects of their spawning migrations are variable, in some instances these fish contribute to increased nutrient concentrations, primary productivity, invertebrate biomass, and resident fish growth and survival in the nutrient‐poor streams of the Pacific Northwest. In tributaries of the Great Lakes, the effects of introduced salmonid and native adfluvial fish are poorly documented. We conducted field experiments to determine the effects of a semelparous fall fish, Chinook salmon Oncorhynchus tshawytscha, and an iteroparous spring fish, steelhead O. mykiss, on the ecology and productivity of two tributaries to the Muskegon River, Michigan, a Lake Michigan tributary. We sampled stream biota and water chemistry before and after the introduction of Chinook salmon carcasses and eggs in the fall and steelhead eggs in the spring in a tributary stream with natural spawning runs and in another tributary stream without runs but with carcass and egg additions. There was no response in terms of invertebrate density or water chemistry to spawning migrations or salmon carcass introductions in either tributary. The density of resident brown trout Salmo trutta increased in both stream types after the introduction of salmon carcasses in the fall, and energy consumption increased after the addition of salmon eggs in the fall and spring in the manipulated stream. Based on stomach content analysis, fish that had eggs in their stomachs also consumed more energy than fish that did not consume eggs. The results suggest that adfluvial fish may affect some tributaries of the Great Lakes by providing high‐energy food sources to resident stream fish, but the potential effect of this egg consumption on resident fish growth and survival requires more research.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141037/1/tafs1670.pd

Intense winter heterotrophic production stimulated by benthic resuspension

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109851/1/lno20004571672.pd

Seasonal changes in the respiratory electron transport system (ETS) and respiration of the zebra mussel, Dreissena polymorpha in Saginaw Bay, Lake Huron

Electron transport system activity (ETS) and respiration rates (R) of the zebra mussel, Dreissena polymorpha , were determined monthly from April to November over 2 years at two sites in Saginaw Bay, Lake Huron. The sites were located in the inner and outer bay and contrasted in food quantity and quality. ETS ranged from 2 to 40 μg O 2 mg DW −1 h −1 over the study period. Both ETS and respiration were strongly related to temperature, and maximum values were found between June and August. ETS also peaked in June/July when assays were conducted at a constant temperature (25 °C), indicating other factors besides temperature affected metabolic activity. R:ETS ratios decreased with increased temperature at the inner bay site, but trends were minimal at the outer bay site. In late summer, blooms of the cyanophyte Microcystis occurred in the inner bay, likely depressing filtration rates, and leading to lower respiration rates relative to ETS. ETS activity was consistently higher in the outer bay and was likely a result of higher food quality. Despite these spatial differences, annual mean R:ETS ratios varied only from 0.04 to 0.09 at the two sites over the 2-year period. Based on these values, ETS may be useful as an indicator of long-term metabolic activity in annual energy budgets of D. polymorpha . However, food conditions differentially affect respiration relative to ETS, and variability in this ratio must be considered when interested in shorter time scales.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42896/1/10750_2004_Article_334245.pd

Seston quality drives feeding, stoichiometry and excretion of zebra mussels

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136507/1/fwb12892.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136507/2/fwb12892_am.pd

Distribution and dynamics of nitrogen and microbial plankton in southern Lake Michigan during spring transition 1999–2000

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95655/1/jgrc9187.pd

In situ hatching of invertebrate diapausing eggs from ships’ ballast sediment

Ships that enter the Great Lakes laden with cargo carry only residual ballast water and sediment in ballast tanks. These ships are designated ‘no ballast on board’ (NOBOB) and constitute > 90% of inbound traffic. We conducted in situ experiments using emergence traps to assess the viability and the introduction potential of invertebrate diapausing stages present in ships’ ballast sediment. All trials commenced while vessels operated on the lower lakes (Erie, Ontario) and were completed 6–11 days later at ports on the upper lakes (Michigan, Lake Superior). Eight trials were conducted on four ships using five different ballast sediments. Hatching was observed on every ship, although not from all sediments on all ships. Overall hatch rates were very low (0.5 individuals per 500 g sediment), typically involving activation of < 0.05% of total eggs present. Five species of rotifers and copepod nauplii were hatched from ballast sediments, although only one or two species typically hatched from any one sediment. Results of this study indicate that hatching of diapausing eggs contained in ballast sediment of NOBOB ships poses a relatively low risk of invasion to the Great Lakes. However, as reproduction may occur in tanks, and non-indigenous species may be involved in numerous introduction events, the risk posed by this vector is small but potentially important. While dormancy is a characteristic enabling enhanced survival during transportation in ballast tanks, it becomes a hindrance for introduction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72804/1/j.1366-9516.2005.00150.x.pd

Lake Erie hypoxia prompts Canada‐U.S. study

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95631/1/eost15589.pd

Exurban Residential Subdivision Development: Effects on Water Quality and Public Perception

We investigated how future alternative designs for exurban residential subdivision development in agricultural landscapes might affect aquatic ecosystems and public perceptions, and we asked whether better aquatic ecological quality would correspond with public perceptions of greater landscape attractiveness. The alternative exurban features we compared were: ecologically beneficial subdivisions, conventional subdivisions, and conventional agriculture. To judge their aquatic ecology effects we measured the chemistry and biota of six first-order streams within our study area, the Huron and Raisin River watersheds in the Detroit CMSA. We chose two stream catchments that exibited land cover to represent the same proportions as each of three types of alternative exurban features. Streams in catchments representing ecologically beneficial subdivision designs had the most total macroinvertebrate taxa, the most sensitive macroinvertebrate taxa, lowest nitrates, lowest total phosphorus, and lowest total suspended materials. Nutrient concentrations were highest in agricultural catchments, and suspended sediments were highest in conventional subdivision catchments. To compare public perceptions of the alternative futures, we surveyed 336 suburban and exurban adult residents of the upper Midwest. All respondents viewed digital imaging simulations of each of the futures and rated their attractiveness as if they were seen from the window of a home in the area. Ecologically beneficial futures were perceived as most attractive. Comparing the alternative futures, rankings of aquatic ecological quality were consistent with public perceptions of attractiveness.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49341/1/UrbEco04.pd

Spatial-temporal variability of in situ cyanobacteria vertical structure in Western Lake Erie: Implications for remote sensing observations

Remote sensing has provided expanded temporal and spatial range to the study of harmful algal blooms (cyanoHABs) in western Lake Erie, allowing for a greater understanding of bloom dynamics than is possible through in situ sampling. However, satellites are limited in their ability to specifically target cyanobacteria and can only observe the water within the first optical depth. This limits the ability of remote sensing to make conclusions about full water column cyanoHAB biomass if cyanobacteria are vertically stratified. FluoroProbe data were collected at nine stations across western Lake Erie in 2015 and 2016 and analyzed to characterize spatio-temporal variability in cyanobacteria vertical structure. Cyanobacteria were generally homogenously distributed during the growing season except under certain conditions. As water depth increased and high surface layer concentrations were observed, cyanobacteria were found to be more vertically stratified and the assumption of homogeneity was less supported. Cyanobacteria vertical distribution was related to wind speed and wave height, with increased stratification at low wind speeds (bathymetry and environmental conditions could lead to improved biomass estimates. Additionally, cyanobacteria contributions to total chlorophyll-a were shown to change throughout the season and across depth, suggesting the need for remote sensing algorithms to specifically identify cyanobacteria

Physical-Biological Coupling in Southern Lake Michigan: Influence of Episodic Sediment Resuspension on Phytoplankton

The influence of episodic, sediment resuspension on phytoplankton abundance/volume and composition, the photosynthetic maximum rate (P B max ) and efficiency (α B ), and chlorophyll-specific growth (μ Chl ) was evaluated during the spring isothermal period in southern Lake Michigan (Laurentian Great Lakes, USA). Resuspension altered the nutrient and light climate of nearshore waters; light attenuation (K d ) and phosphorus concentrations corresponded (p ≤ 0.0001 and p ≤ 0.001, respectively) with concentrations of suspended particulate matter (SPM). Phytoplankton cell volume and diatom cell abundance and volume were not associated with SPM concentrations (p > 0.05). Diatom composition displayed spatial dissimilarities corresponding with resuspension (p ≤ 0.001); small centric diatoms exhibiting meroplanktonic life histories and pennate diatoms considered benthic in origin were most abundant within SPM-impacted, nearshore waters whereas taxa typically comprising assemblages in optically-clear, offshore waters and the basin-wide, spring bloom were not. Values of P B max and α B corresponded (p ≤ 0.0001) with both K d coefficients and SPM concentrations, potentially reflecting increased light harvesting/utilization within impacted assemblages. However, integral production was inversely associated with K d coefficients and SPM concentrations (p < 0.0001) and photosynthesis was light-limited (or nearly so) for most assemblages. Although μ Chl values corresponded with K d coefficients (p ≤ 0.05), values were quite low (x ± S.E., 0.10 ± 0.004 d -1 ) throughout the study. Most likely, distinct rate processes between SPM- and non-impacted assemblages reflected short-term compositional (and corresponding physiological) variations due to infusion of meroplankton and/or tributary-derived phytoplankton. Overall, resuspension appears to have little, if any, long-term impact upon the structure and function of the lake’s phytoplankton.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41735/1/10452_2004_Article_5149255.pd