SFS Annual Meeting

5/23/2019  |   11:00 - 11:15   |  151 ABC

PHYSIOLOGICAL PERSPECTIVES IN FRESHWATER SALINIZATION RESEARCH The changing salinity of freshwater ecosystems has emerged as an ecological issue throughout the world because biodiversity losses are often associated with these changes. Regulatory entities have been slow to respond to this issue, in part, because our scientific understanding of how salinity affects biota is relatively poor. At the physiological level, it remains unclear whether salinity effects arise from toxic concentrations of individual ions, interactions among ions, or the overall salinity of all ions in solution. Further, we don’t yet understand if toxicity arises from a dysregulation of ion content in body fluids, or whether the energetic costs of regulating internal ionic composition is more relevant to understanding salinity effects. In this talk, I will synthesize recent research that highlights the potential importance of the energetics of osmoregulation in aquatic insects. I will further discuss how an interactive blend of lab-based and field-based research is needed to better understand this complex issue.

David Buchwalter (Primary Presenter/Author), North Carolina State University, david_buchwalter@ncsu.edu;


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5/23/2019  |   11:15 - 11:30   |  151 ABC

DOES TEMPERATURE INFLUENCE ION TRANSPORT IN AQUATIC INSECTS? Temperature and salinity are critical abiotic factors that strongly influence the global distribution of aquatic organisms. Many aquatic ecosystems are simultaneously becoming warmer and saltier, but our understanding of how the interactions between these factors affect the physiology and life history outcomes of most aquatic species remain unknown. Work in our laboratory is beginning to explore the influence of temperature on ion transport rates in aquatic insects. We are testing the hypothesis that increasing metabolic rates associated with increasing temperatures may increase ion turnover rates, which may present additional energetic costs. For example, increasing temperature from 15°C to 25°C, increased 22-Na uptake rates by two-fold (P<0.0001) and 35-SO4 uptake rates by four-fold (P<0.0001) in Hydropsyche sp.. Smaller changes in 22-Na uptake rates were observed in Isonychia sp. and Maccaffertium sp. suggesting species-specific differences in the thermal sensitivity of ion transport. We will present research on the relationships among temperature, metabolic rates, and ion transport rates in both field collected and laboratory reared aquatic insects. Conceivably, the energetic cost of osmoregulation in warmer, saltier environments may lead to detrimental effects on certain species of freshwater insects.

Sarah Orr (Primary Presenter/Author), North Carolina State University, seorr@ncsu.edu;


David Buchwalter (Co-Presenter/Co-Author), North Carolina State University, dbbuchwa@ncsu.edu;


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5/23/2019  |   11:30 - 11:45   |  151 ABC

EFFECTS OF SALINITY AND TEMPERATURE ON GROWTH, SURVIVAL, AND ADULT EMERGENCE IN THE DESERT CADDISFLY LIMNEPHILUS ASSIMILIS BANKS Study of species from extreme environments can inform predictions of effects of salinization and changed thermal regimes resulting from climate change and various human activities. We monitored growth, survival and adult emergence in the desert caddisfly Limnephilus assimilis by holding larvae in cages over a range of salinities and temperatures. In field experiments at Salt Creek (15-18 ppt salinity) and Saratoga Springs (3 ppt) in Death Valley, CA, larval growth rates, mortality rates, and emergence did not differ significantly between habitats. Reciprocal transfers of larvae between habitats showed equal emergence at Saratoga Springs; at Salt Creek, most larvae originating at Saratoga Springs died, but a small proportion of transferred larvae emerged successfully emerged. Full factorial laboratory experiments with salinities of 1-25 ppt and temperatures of 5-25 C showed (1) 100% larval mortality at 25 C, with mortality rates increasing with salinity; (2) no successful emergence at 22 and 25 ppt salinity, with mortality rates at all salinities increasing with temperature; (3) decreasing adult emergence with increasing salinity but a small proportion of emergence at 18 and 20 ppt at low-to-moderate temperatures. Such plasticity may help species adapt to environmental change.

Betsy Colburn (Primary Presenter/Author), Harvard Forest, colburn@fas.harvard.edu;


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5/23/2019  |   11:45 - 12:00   |  151 ABC

TEMPORAL AND SPATIAL EXTENT OF SURFACE COAL MINING INFLUENCES ON CENTRAL APPALACHIAN HEADWATER STREAMS Increased loading of dissolved ions (salinization) is a primary alteration to headwater streams in the central Appalachian coalfield. However, temporal and spatial trends of increased dissolved ions and associated influences on biota have not been well studied. To address this research need, we analyzed temporal trends in specific conductance, benthic macroinvertebrate communities, and ion matrix in 24 headwater streams from 2011-2019. To date, there is limited evidence of recovery of water chemistry or aquatic life in these streams indicating, lasting impacts from surface coal mining. We analyzed spatial patterns of water chemistry in a subset of these streams using synoptic sampling of multiple constitutes every 100m under high and low flow conditions. Preliminary results indicate that water chemistry is spatially dynamic and can be influenced by several processes including dilution and source activation. Lastly, we investigated spatial patterns of selenium bioaccumulation from particulate matter to top trophic levels including fish and salamanders and found limited evidence of increased selenium bioaccumulation downstream of a single source. Our work indicates persistent coal mining influences but also highlights future research needs to better understand downstream impacts to water quality and biotic communities.

Thomas Cianciolo (Primary Presenter/Author), Virginia Tech, thomrc6@vt.edu;


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5/23/2019  |   12:00 - 12:15   |  151 ABC

CAPTURING BENTHIC MACROINVERTEBRATE TAXA RICHNESS ACROSS A SALINITY GRADIENT IN CENTRAL APPALACHIAN HEADWATER STREAMS Anthropogenic salinization is a global concern as human activities such as road de-icing, agriculture, and mining introduce increased levels of ions to freshwaters. Headwater streams draining coalfields in central Appalachia have elevated levels of sulfate and associated major ions that alter benthic macroinvertebrate community structure by decreasing diversity of salt-sensitive taxa. Less is known about how elevated salinity affects macroinvertebrate densities and their functions because quantitative sampling is less common. Taxa accumulation curves identify the sample effort (i.e. the number of samples) required to capture representative metrics. In April of 2014, three Surber samples were collected from riffles of 15 headwater streams (N=45) across a salinity gradient (~25-1500 µS/cm). The estimated number of samples needed was predicted to decrease as salinity increased because salinity negatively impacts taxa richness. Preliminary accumulation curves suggest decreases in taxa richness with increased salinity as curves level off sooner. Reference sites continue to have higher slopes that reach higher asymptote values, suggesting more than three Surber samples were required to capture taxa richness. We will present complete accumulation curves that inform future quantitative sampling efforts and functional metrics in relation to salinity.

Aryanna James (Primary Presenter/Author), Virginia Tech, aryannaj@vt.edu;


Rachel Pence (Co-Presenter/Co-Author), Virginia Tech, pencera@vt.edu;


Sally Entrekin (Co-Presenter/Co-Author), Virginia Tech, sallye@vt.edu;


Carl Zipper (Co-Presenter/Co-Author), Virginia Tech, czip@vt.edu;


Anthony Timpano (Co-Presenter/Co-Author), Virginia Tech, atimpano@vt.edu;


Stephen Schoenholtz (Co-Presenter/Co-Author), Virginia Tech, schoenhs@vt.edu;


Daniel McLaughlin (Co-Presenter/Co-Author), Virginia Tech, mclaugd@vt.edu;


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5/23/2019  |   12:15 - 12:30   |  151 ABC

DOES SAMPLE TIMING MATTER? INVESTIGATING WHEN TO SAMPLE FORESTED HEADWATER STREAMS FOR ASSESSING FRESHWATER SALINIZATION IMPACTS TO BENTHIC MACROINVERTEBRATES. Effective monitoring and management of aquatic-life effects from freshwater salinization can be advanced through accurate description of how salinity influences benthic macroinvertebrate assemblages. However, linking salinity to biological effects is complicated because salinity and benthic macroinvertebrate sample composition often vary throughout the year. Therefore, ideal salinity-biota associations will account for the annual cycle of salinity variation and link it to organism exposure at a particular life stage. Assessment of benthic macroinvertebrate responses to salinization, such as occurs in central Appalachian (USA) streams salinized by coal mining, is typically conducted by associating macroinvertebrate assemblage structure with salinity sampled concurrently. This “snapshot” approach assesses stream conditions at a single point in time but does not capture temporal variability of salinity or macroinvertebrate sample composition. To evaluate how sample timing might influence conclusions drawn about salinity effects to aquatic life, we investigated whether measures of salinity that integrate exposure over time, or represent certain periods of time that may correspond with sensitive life stages of taxa, may be more accurate than snapshot salinity in predicting macroinvertebrate assemblage structure. Ensuring decisions are based on accurate linkages between salinity and biota should yield effective management.

Anthony Timpano (Primary Presenter/Author), Virginia Tech, atimpano@vt.edu;


Carl Zipper (Co-Presenter/Co-Author), Virginia Tech, czip@vt.edu;


David Soucek (Co-Presenter/Co-Author), Illinois Natural History Survey, soucek@illinois.edu;


Stephen Schoenholtz (Co-Presenter/Co-Author), Virginia Tech, schoenhs@vt.edu;


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