SFS Annual Meeting

5/20/2019  |   11:00 - 11:15   |  150 DEF

CURRENT DISTRIBUTIONS AND FUTURE CLIMATE-DRIVEN CHANGES IN DIATOMS, INSECTS, AND FISH IN U.S. STREAMS Climate and land use changes are among the biggest threats to global biodiversity. The development of large-scale modeling techniques, particularly species distribution models (SDMs), presents a powerful opportunity to predict species distributions from known species-environmental relationships and assess potential fallouts of anthropogenic impacts. Despite the vulnerability of freshwater diversity to global change, SDMs have been heavily biased toward terrestrial systems. We examined the distributions of diatoms, aquatic insects, and fish throughout the coterminous United States using chemistry, watershed, climate, and combined models. We further investigated the modeling strength and projected distribution changes of warm- versus cold-water taxa under mitigated, stabilizing, and increasing greenhouse gas emissions. Across all three organismal groups, climate emerged as the strongest predictor of species distributions. Subsequent SDMs using climatic predictors suggest widespread increase of warm water taxa, while cold water taxa decline in streams where they are currently most abundant. Eradication of such source habitats, which support populations in localities with less favorable conditions through immigration, may limit the regional distributions of cold-adapted biota with negative consequences for ecosystem function, resistance, and resilience.

Katrina Pound (Primary Presenter/Author), University of Texas - Arlington, katrina@uta.edu;


Chad Larson (Co-Presenter/Co-Author), Washington State Department of Ecology, clar461@ecy.wa.gov;


Sophia Passy (Co-Presenter/Co-Author), University of Texas - Arlington, sophia.passy@uta.edu;


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5/20/2019  |   11:15 - 11:30   |  150 DEF

HOW DO WE RESPOND TO ECOLOGICAL TRANSFORMATIONS: RESIST, ACCEPT, OR DIRECT? Ecological transformation, the reorganization of an ecosystem from one state into another, has always occurred but in the age of the Anthropocene, transformations are occurring at an unprecedented scale and rate. Traditional conservation-oriented management approaches seek to resist these changes, attempting to maintain ecosystems within a historical range of variability or restore them back to a pre-defined natural state. However, given the directional force of climate change, resistance will become increasingly difficult, expensive, and under many circumstances, impossible. We now need to intentionally consider and identify those situations where we can realistically resist change, where we must accept change, or in some cases even direct ecosystems to a desirable future state. Land management agencies currently lack guidance on managing across the resist, accept, direct (RAD) continuum, especially when we move into the realm of directing change. In this presentation we will introduce the RAD management framework intended to address this challenge, and using cases studies illustrate some of the key considerations we will face when managing systems experiencing ecological transformation. This work represents the efforts of two active working groups tackling this issue.

David Lawrence (Primary Presenter/Author), National Park Service, Climate Change Response Program, david_james_lawrence@nps.gov;


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5/20/2019  |   11:30 - 11:45   |  150 DEF

EFFECTS OF WATER TEMPERATURE UNDER PROJECTED CLIMATE CHANGE ON THE DEVELOPMENT AND SURVIVAL OF THE FAMILIAR BLUET DAMSELFLY (ENALLAGMA CIVILE) Climate and land-use changes are the primary threats to aquatic invertebrate communities around the world. Within the Southern High Plains of North America, current climate change projections estimate increased air temperatures by 2 to 4°C, putting many aquatic organisms at risk from environmental changes affecting nymph and adult life stages. Increased air temperatures can lead to elevated water temperatures, but experiments are lacking on responses in terms of development or survival. The familiar bluet damselfly (Enallagma civile) was used as a model organism to study the effects of projected water heating on playa invertebrates. Eggs were collected and reared under four water temperature regimes (26, 32, 38, and 41°C). Nymph body measurements after molts, development rate, and deaths were recorded daily. Elevated water temperature was found to significantly affect all life stages. Nymphs in the two hotter treatments were smaller and had lower survivorship whereas individuals in the cooler temperatures generally survived to adulthood and were larger. Individuals reared at 32°C emerged the quickest, going from egg to adult in 26 days. Elevated temperatures can thus be both advantageous and detrimental, causing concern for aquatic invertebrates in the future.

Scott Starr (Primary Presenter/Author), Biology Department, South Plains College, Levelland, TX 79336, sstarr@southplainscollege.edu;


Nancy McIntyre (Co-Presenter/Co-Author), Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409-3131, nancy.mcintyre@ttu.edu;


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5/20/2019  |   11:45 - 12:00   |  150 DEF

HETEROGENEOUS FISH RECOLONIZATION ALONG A CLIMATE GRADIENT FOLLOWING HURRICANE HARVEY A category 4 hurricane, Harvey, made landfall in the Texas Coastal Bend on August 25, 2017 bringing extreme floods and high winds. The frequency and intensity of similar storms are expected to increase in many regions as global temperatures rise (IPCC 2018). Here, we evaluate the impact of climate drivers on fish community responses and recovery rates to this storm. Prior to and after the hurricane, we performed monthly surveys of 9 streams spanning a semi-arid to sub-humid precipitation gradient along the Texas Gulf Coast. Surveys assessed nutrients (SRP: NH4+, NO3-), water chemistry, habitat characteristics and fish communities. Fish sampling was performed using a 3-pass depletion survey design within a 75m reach bounded by block nets. Fish community assemblage dynamics were evaluated using diversity indices and non-metric multidimensional scaling. Climate drivers of fish recolonization were evaluated by correlating species and diversity recovery with environmental factors. Fish community abundances recovered quickly with varying compositional and diversity recovery rates. Our results indicate a universal flood-pulse response to disturbance in which fish communities in streams with wetter climates take more time to reestablish pre-storm community states.

Fernando Carvallo (Co-Presenter/Co-Author), Texas A&M University–Corpus Christi, fcarvallo@islander.tamucc.edu ;


Darcia Gonzalez (Co-Presenter/Co-Author), Texas A&M Corpus Christi, dgonzalez16@islander.tamucc.edu;


Alexander Solis (Co-Presenter/Co-Author), VIMS, alexander.tr.solis@gmail.com;


Brandi K. Reese (Co-Presenter/Co-Author), Texas A&M Corpus Christi, brandi.reese@tamucc.edu;


James Hogan (Co-Presenter/Co-Author), Texas A&M University – Corpus Christi, james.hogan@tamucc.edu;


Christopher Patrick (Co-Presenter/Co-Author), Virginia Institute of Marine Science (VIMS), cpatrick@vims.edu;


Sean Kinard (Primary Presenter/Author), Virginia Institute of Marine Science, s2kinard@gmail.com;


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5/20/2019  |   12:00 - 12:15   |  150 DEF

LIGHT VS. NUTRIENT EFFECTS OF DOM ON BENTHIC PRODUCTION IN NORTHERN LAKES Among lakes, observed hump-shaped relationships between gross primary production (GPP) and dissolved organic matter (DOM) are hypothesized to result from nutrient supply (positive relationship) and light absorption (negative relationship). To test these mechanisms, we used nutrient diffusing substrata (NDS) to examine benthic biofilm growth and type/strength of limitation among lakes along a DOM gradient. While we did not observe a clear relationship between biofilm growth and DOM in unamended controls, nutrient limitation differed along the gradient. At low DOM, we saw limitation by N alone, at moderate DOM there was primary limitation by N and secondary limitation by P, while at higher DOM light limitation superseded the effects of added nutrients. In four lakes, we incubated NDS at three depths to isolate effects of nutrient supply and light. In clearer lakes, chl-a in controls was consistently low, while in the darkest lake, shallow deployments had the highest chl-a. In contrast, we observed the largest responses to added N in shallow incubations of the clearest lakes. These results support the hypothesis of dual control of terrestrial DOM on GPP via nutrients and light, creating a nonlinear relationship between GPP and DOM.

Megan Fork (Primary Presenter/Author), West Chester University, mfork@wcupa.edu;


Jan Karlsson (Co-Presenter/Co-Author), Umeå University, jan.p.karlsson@emg.umu.se;


Ryan Sponseller (Co-Presenter/Co-Author), Department of Ecology and Environmental Science, Umeå University, 901 87 Umeå, Sweden, ryan.sponseller@umu.se;


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