10:30-11:30 AM Podium Session Session 01 Lake Erie Ecosystems Room 427.
Where a stream enters a large lake, the mouth will likely represent a mixed environment that is neither truly lotie nor lentic in nature. Consequently, what freshwater mussel (Unionidae) assemblages live in this heterogeneous system is poorly understood. The lower reaches of nine small tributaries of the western and central basins of Lake Erie were sampled for mussels in 2010 by sight, feel and with mussel rakes followed by similar surveys in 2011-2012 on three more streams and the large embayments of Muddy Creek and Sandusky Bay. Together, these systems composed 15 localities varying from 10 to 4000 km2 in watershed size. Regional land use was assessed by remote sensing, and basic water chemistry was measured by standard protocols. Evidence of unionid mussels occurred in all 15 localities, with 13 species found alive, but no live unionids were found in two streams. Dreissenid mussels were rarely encountered. The intercept of a regression of log-watershed size on species number approached zero, meaning mussels can occur in very small lake-influenced inlets, but the slope was just 1/6 that for rivers, indicating that species numbers increase slowly with greater watershed size. Low variation in both water chemistry and land use reduced their explanatory power although presence of bare fields probably contributed to high turbidity, the one water quality measure correlated with abundance. That feature may explain the increased presence of Quadrula quadrula and Pyganodon grandis, which tolerate depositional, low-flow environments, while the interchange of water may provide a refuge habitat for these native mussels.
10:45 - VARIATION IN FINGERNAIL AND PEA CLAM (SPHAERIIDAE) POPULATIONS IN LAKE ERIE. Taylor R. Schilling (email@example.com) and Robert A. Krebs (firstname.lastname@example.org). Dept. of Biological, Geological and Environmental Sciences, Cleveland State University, 28886 Alton Rd, Wickliffe, OH 44092.
Small clams in the family Sphaeriidae consist of the genera Musculium, Sphaeriium, and Pisidium. Although these clams are known from the Laurentian Great Lakes of the United States and Canada, this study focuses on the variation of sphaeriids between the central and western basins of Lake Erie. Since the samples were collected from this one body of water, less variation within a species was predicted compared to published literature on samples taken from across North America. The height/length (H/L) and width/length (W/L) ratios of the clams were used to aid in species identification and then to compare size and meristic variation within species. Surprisingly, variation levels in the lake were as high as that reported in the northern United States as a whole, and similarly, community composition was as diverse. But, while the western basin contained all three genera with Pisidium least common, the deeper waters of the central basin contained almost entirely Pisidium, and the assemblage consisted of up to 12 species at one site and 19 species across the central basin. Samples from Old Woman Creek (OWC), a freshwater estuary near Huron, Ohio, were also surveyed to test whether communities would follow that predicted for shallow waters or for the central basin fauna to which it drained. An initial survey identified a Pisidium-Musculium mix, however, recent hypoxic conditions led us to find no additional living clams.
11:00 - THE ROLE OF TRACE NUTRIENT LIMITATION IN THE CENTRAL BASIN OF LAKE ERIE CYANOBACTERIAL BLOOMS. Brittany Dalton (12) (email@example.com) and Justin Chaffin (1) (firstname.lastname@example.org). (1) Franz Theodore Stone Laboratory, The Ohio State University, P.O. Box 119, 878 Bayview Road, Put-In-Bay, Oh 43456, (2) Cleveland State University, 2121 Euclid Avenue, Cleveland, Oh 44115.
Periodic summer blooms of the diazotrophic cyanobacterium Dolichospermum occur in the central basin of Lake Erie. High concentrations of nitrates and low phosphorus (P) make the presence of Dolichospermum in the central basin enigmatic. Trace nutrients molybdenum (Mo) and iron (Fe) are needed for nitrate-nitrogen (N) assimilation and low concentrations of these nutrients may create N limitation even with nitrate present. Six nutrient enrichment bottle bioassays were conducted using offshore central basin water from June 2 to August 26 in 2016 to determine which nutrient(s) limited algal growth and we hypothesized that more growth would occur when P(1[micro]M) and trace nutrients, Fe(0.5 [micro]M), Mo(0.1 [micro]M), were enriched together compared with P-only enrichment. Chlorophyll a (Chla) (proxy for phytoplankton biomass) and ambient nitrate concentration were measured before and after incubation. In all experiments, P-only treatments demonstrated significantly (P<0.001, ANOVA) higher Chla (2.70 pg/L to 15.92 pg/L) than control (1.09 pg/L to 3.33 pg/L), which indicated a primary P-limitation. Enrichments of P with trace nutrients resulted in higher Chla than P-only in 3 of the 6 experiments and enrichments of P and ammonium-N resulted in highest Chla in 5 of the 6 experiments, indicating that other nutrients constrained growth. However, ambient nitrate concentration post incubation did not differ (P > 0.05) between P-only and P with trace nutrients in any experiments, indicating that Fe and Mo did not limit nitrate assimilation. Therefore, the trace nutrient colimitation in the central basin may favor Dolichospermum typically associated with high P and low N.
11:15 - ACCURACY OF DATA BUOYS FOR MONITORING HARMFUL ALGAL BLOOMS IN LAKE ERIE. Justin D. Chaffin (1) (Chaffin.email@example.com) and Douglas D. Kane (1,2) (firstname.lastname@example.org). (1) Franz Theodore Stone Laboratory, Ohio State University, 878 Bayview Ave., Putin-Bay, Ohio 43456, (2) Defiance College.
Real-time data buoys have become a valuable tool for lake managers, water treatment plant operators, and the public to monitor cyanobacterial (cHAB) abundance in Lake Erie. However, the buoys utilize sensors that measure total algae and cHABs by fluorescence, which is an indirect proxy for chlorophyll concentration. Furthermore, the sensors on the buoys are located about 0.6 m from the surface, whereas cHABs can regulate buoyancy and may be over or underestimated by the buoy sensors. The objective of this project was to determine how accurate data buoys are at monitoring for cHABs. Surface water samples (0-2 meter, n=147) were collected next to a data buoy located near Gibraltar Island throughout summers 2015 and 2016 and analyzed for total chlorophyll and with a fluorometric instrument (FluoroProbe) to determine cHAB-specific chlorophyll. Additionally, on a subset of dates (n=34) water was collected at every meter throughout the water column to determine vertical position of cHAB. cHAB-specific chlorophyll concentration measured in surface water samples peaked in late July 2015 at 116 ppb and had a very strong positive linear relationship with the buoy cHAB sensor ([R.sup.2] = 0.96). However, there was a weaker relationship between total chlorophyll and the buoy chlorophyll sensor ([R.sup.2]- < 0.50). The every-meter sampling indicated that cHAB were spread evenly throughout the water column or increased in concentrations towards the surface. Surface cHAB accumulations led to a few inconsistencies between the buoy data and every-meter data that could potentially lead to inaccurate warnings and water treatment procedures.
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|Publication:||The Ohio Journal of Science|
|Date:||Apr 1, 2017|
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