SFS Annual Meeting

5/24/2018  |   09:00 - 09:15   |  410 B

DESCRIPTION OF THE Chironomus sp. (Diptera, Chironomidae) NEUROMUSCULAR SYSTEM: A TOOL FOR FUTURE FRESHWATER ECOTOXICOLOGICAL EVALUATIONS IN PUERTO RICO Ecotoxicological studies have used the Drosophila melanogaster neuromuscular junction (NMJ) as a biomarker. Unfortunately, this model is ineffective to evaluate toxicity in freshwater ecosystems. Water and sediment toxicities have been evaluated with organisms from the Chironomidae family, but their NMJ anatomy, due to lack of information, has not been used as a biomarker for ecotoxicological assays. The aim of this study is to describe the NMJ anatomy of a Puerto Rican Chironomus sp. and establish it as a reference for future use in freshwater ecotoxicological evaluations in the island. To achieve this, we dissected laboratory reared larvae and immunolabelled them for a series of NMJ molecules. Using confocal microscopy, we then described the nervous and muscular systems of the thoracic and abdominal segments. The central nervous system is composed by a brain and a ventral nerve cord. We observe three types of ganglions in the nerve cord, from which axons connect with ventral muscles. Upon contact of the nerves with the muscle fibers, a series of varicosities (NMJ) is also observed. This description can result in a useful tool for freshwater ecotoxicological assays if the necessary validation studies are pursued.

Roberto Reyes-Maldonado (Primary Presenter/Author), University of Puerto Rico, Rio Piedras, robertoomaldo@gmail.com;


Kevin De Leon (Co-Presenter/Co-Author), University of Puerto Rico, Institute of Neurobiology, kevindeleonupr@gmail.com;


Bruno Marie (Co-Presenter/Co-Author), University of Puerto Rico, Institute of Neurobiology, brunomariemail@gmail.com;


Alonso Ramírez (Co-Presenter/Co-Author), North Carolina State University, alonso.ramirez@ncsu.edu;


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5/24/2018  |   09:15 - 09:30   |  410 B

STREAM MESOCOSM PHOSPHORUS DOSE-RESPONSE VALIDATION STUDY Validating stream nutrient targets for water quality management with experiments that can demonstrate causal effects on biota lends confidence to the users and stakeholders of such targets. Numeric nutrient thresholds are based on correlation-type analyses using data from multiple field sites and linkage variables like dissolved oxygen to indicate the mechanism causing biological impairment. To help validate thresholds determined from field data, we conducted a replicated mesocosm dose-response study with nominal dissolved phosphate treatments of <15, 40, 100, 300, 600, and 1200 ppb using an ecotoxicology framework. Dose effects on the periphytic and macroinvertebrate components of the stream mesocosms were assessed within a community context and with more traditional, single-species toxicity assays run in parallel. Results suggest that there were differences in the periphyton community occurring between the 100 and 300 ppb phosphate treatments that coincided with a significant effect on insect emergence. Specifically, the emergence of adult Tanytarsini chironomids decayed exponentially with dose producing a 20% effective total phosphorus concentration (ppb) response (i.e., EC20) of 148 ± 60 ppb.

Paul Weaver (Co-Presenter/Co-Author), U.S. Environmental Protection Agency, weaver.paul@epa.gov;


Jim Lazorchak (Co-Presenter/Co-Author), United States Environmental Protection Agency, Office of Research and Development, Center for Environmental Measurement and Modeling, Cincinnati, OH 45268, lazorchak.jim@epa.gov;


Nathan Smucker (Co-Presenter/Co-Author), U.S. Environmental Protection Agency, smucker.nathan@epa.gov;


Christopher Nietch (Primary Presenter/Author), U.S. Environmental Protection Agency, nietch.christopher@epa.gov;


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5/24/2018  |   09:30 - 09:45   |  410 B

FRESHWATER SALINIZATION: MULTI-YEAR STUDY REVEALS NATURAL SEASONAL SALINITY PATTERN, IMPLICATIONS FOR MACROINVERTEBRATE LIFE-CYCLE EXPOSURE Salinization of freshwaters is of growing concern globally. In many regions of the world, and in coal-mining-influenced streams of Appalachia USA, specific conductance (SC; a salinity surrogate) has been linked to decreased diversity of benthic macroinvertebrates. Effective management of salinization requires accurately linking salinity with biological effects while accounting for temporal variability. Toward that end, we sampled high-frequency SC and seasonal benthic macroinvertebrates for 4.5 years in 25 Appalachian headwater streams spanning a gradient of salinity. A sinusoidal model of the annual cycle of SC revealed that on average, salinity naturally deviated ± 20% from annual mean levels, with minimum SC occurring in late winter and maximum SC occurring in late summer. Community structure diverged from reference condition as salinity increased, with stronger relationships in Spring than in Fall. Non-Baetidae Ephemeroptera in Spring samples were most sensitive to salinity, with declines in richness and abundance predicted when Spring SC was > 200 uS/cm and when SC during the prior Fall was > 250-300 uS/cm. This study demonstrates transferable tools that can account for natural temporal variability and allow characterization of life-cycle exposures when assessing biological effects in salinized waters.

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;


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


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5/24/2018  |   09:45 - 10:00   |  410 B

STREAM BEDFORM AND HYPORHEIC FLOWS: EFFECTS ON METAL BIOAVAILABILITY AND BIOLOGICAL COMMUNITIES IN SEDIMENTS In metal contaminated streams, the direction of hyporheic flow (upwelling or downwelling) may influence sediment redox conditions and metal speciation, resulting in a range of effects for aquatic organisms. This study investigates the potential for metal toxicity in the head (upstream) and tail (downstream) ends of riffles in a Southeastern Michigan stream. In situ experiments were paired with artificial stream mesocosms. Sediments from a stream with low zinc contamination were deployed for 30 days and effects to sediment geochemistry, metal chemistry, biofilms and benthic macroinvertebrates were assessed. The riffle head was more oxidized and had higher pH. The more oxidized conditions correlated with greater bioavailable metals (i.e., (SEM-AVS)/fOC). Similar results from pH and redox were found in the mesocosm experiments. In the in situ experiment, macroinvertebrate community diversity and sensitivity were higher in the riffle head, where risk to metal contamination was higher. Biofilm net primary production declined with increased (SEM-AVS)/fOC. This research suggests that stream bedform location can alter processes in the hyporheic zone by affecting redox conditions, and if metal concentrations are high enough, could increase exposure of metals to aquatic biota.

Anna Harrison (Primary Presenter/Author), Institute for Great Lakes Research, Central Michigan University, harri25a@cmich.edu;


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5/24/2018  |   10:00 - 10:15   |  410 B

DETECTION OF ESTROGENIC HORMONES AND UV-FILTERS IN VIRILE CRAYFISH (ORCONECTES VIRILIS) IN URBAN STREAMS NEAR BALTIMORE, MARYLAND Ultraviolet-filters (UV-filters) in sunscreens and estrogenic hormones are endocrine-disrupting chemicals (EDCs) that have attracted increased attention as contaminants of emerging concern (CECs) due to their widespread occurrence in aquatic ecosystems. However, little is known about the bioaccumulation of these CECs in aquatic biota. The objective of this study was to measure five UV-filters and three estrogenic hormones in crayfish tissue to better understand CEC occurrence in urban streams. We collected virile crayfish (Orconectes virilis) from six sites in urban streams near Baltimore, Maryland using a backpack electrofisher. By applying a novel extraction procedure and liquid chromatography tandem mass spectrometry analysis, we simultaneously detected 6 CECs in crayfish tissue. The 4-methylbenzylidene camphor (75–352 ng/g), octocrylene (3–113 ng/g), and homosalate (78–263 ng/g) UV-filters were present in all crayfish samples. In addition, the UV-filters, benzophenone-3 and ethylhexylmethoxycinnamate were detected at concentrations as high as 51 and 83 ng/g, respectively. The synthetic estrogen, 17a-ethinylestradiol, was also present in crayfish tissue at one site at concentrations of 17 ng/g. Ultimately, these findings confirm that invertebrates living in urban streams accumulate CECs in their tissue, raising new concerns for aquatic species.

Ke He (Primary Presenter/Author), University of Maryland, Baltimore County, kehe1@umbc.edu;


Anne Timm (Primary Presenter/Author,Co-Presenter/Co-Author), USDA Forest Service, Northern Research Station, anne.l.timm@usda.gov;


Lee Blaney (Co-Presenter/Co-Author), University of Maryland, Baltimore County, blaney@umbc.edu;


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5/24/2018  |   10:15 - 10:30   |  410 B

USING FIELD DATA TO ASSESS THE TOLERANCE OF FRESHWATER FISH TO ELEVATED IONIC CONCENTRATIONS Recently, anthropogenic sources have increased ion concentrations in freshwaters. We used field data of fish occurrences and specific conductivity to assess the tolerance of freshwater fish to elevated ions. The concentration at which a species was expected to no longer be observed [the extirpation concentration (XC₉₅)] was identified from the 95th percentile of a weighted cumulative frequency distribution for fish species in streams of the central Appalachians. Comparing analyses with fish identified to species or genus, XC₉₅ for most fish genera was biased towards the XC₉₅ of the most tolerant species observed in the genus. Therefore, a genus-level effect threshold was not reliably predictive of species-level effects, unless only one species of a genus occurred in the fish assemblage. The lowest fish species XC₉₅ was 322 μS/cm, and 5% of XC₉₅s were less than 509 μS/cm. Above 509 μS/cm, 41 of 101 fish species declined in occurrence. In comparison, 5% of macroinvertebrate genera XC₉₅s in an analysis of data from the central Appalachians was 300 μS/cm, a value protective of fish. The views expressed are those of the authors and do not necessarily reflect the views or polices of USEPA.

Michael Griffith (Primary Presenter/Author), U.S. Environmental Protection Agency, Office of Research and Development, Center for Environmental Measurement and Modeling, Cincinnati, OH 45268, griffith.michael@epa.gov;


Lei Zheng (Co-Presenter/Co-Author), previously with Tetra Tech, Inc., lei.zheng@hotmail.com;


Susan Cormier (Co-Presenter/Co-Author), USEPA, Cormier, Susan ;


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