SFS Annual Meeting

Ashley Helton (Co-Presenter/Co-Author)
University of Connecticut, ashley.helton@uconn.edu;

Zachary Johnson (Co-Presenter/Co-Author)
U.S. Geological Survey, Washington Water Science Center, zach.c.johnson3@gmail.com ;

Martin Briggs (Co-Presenter/Co-Author)
U. S. Geological Survey, Hydrogeophysics Branch, Storrs, Connecticut, USA, mbriggs@usgs.gov;

Danielle Hare (Primary Presenter/Author)
University of Connecticut, danielle.hare@uconn.edu;

Abstract: Groundwater discharge to streams maintain thermal stability and water quality essential for sustaining many aquatic ecosystems. However, the depth of the contributing groundwater flow path can influence how vulnerable these ecosystems are to landscape and climate modifications. Here we use paired multi-year air-water temperature signals to categorize 1786 varied size stream sites across the continental United States. These categories parse streams with strong shallow or deeper groundwater connectivity from those with reduced groundwater connectivity and sites with thermal regimes likely influenced by major upstream dam operation. Nationally, 40% of non-dam stream sites were identified as having clear groundwater influence, of which approximately 50% are dominated by shallow groundwater. We observed that long-term shallow groundwater signature sites are warming at a similar proportion to sites with reduced groundwater contributions. Sites with deep groundwater signature tended to have long term temperature records that were stable or cooling. When compared to human-modified watershed characteristics streams with thermal regimes closely coupled to air temperature indicating groundwater disconnection. These results demonstrate that the vulnerability of groundwater-influenced streams to warming depends on the relative flow path depth of the source groundwater requiring distinct management strategies.

Hamish Greig (Primary Presenter/Author)
University of Maine, hamish.greig@maine.edu;

Scott Wissinger (Co-Presenter/Co-Author)
Allegheny College, swissing@allegheny.edu;

Jared Balik (Co-Presenter/Co-Author)
Western Colorado University, jbalik@western.edu;

Amanda DelVecchia (Co-Presenter/Co-Author)
University of North Carolina at Chapel Hill, amanda.delvecchia@unc.edu;

Isaac Shepard (Co-Presenter/Co-Author)
University of Maine, isaac.shepard@maine.edu;

Brad Taylor (Co-Presenter/Co-Author)
North Carolina State University Dept. of Applied Ecology; Rocky Mountain Biological Laboratory, bwtaylo3@ncsu.edu ;

Abstract: Shifts in species distributions poleward in latitude and upslope in elevation are among the most commonly reported ecological responses to climate change, yet few studies have explored the impacts of these shifts on ecosystem function. We investigated the ecosystem-level impacts of observed elevational range shifts in a guild of detritivorous caddisflies (Trichoptera: Limnephilidae) in alpine ponds in the Colorado Rockies. We manipulated caddisfly assemblages in microcosms, mesocosms, and cages within ponds to reflect changes in species relative abundance as high elevation resident taxa are replaced by range-expanding taxa from lower elevations. These experimental species replacements altered ecosystem processes linked to detritus decomposition including rates of detritus breakdown and fine particle production. Moreover, these changes in process rates were consistent across experimental units differing in spatial scale and ecological context. These results suggest that species range shifts can alter detritus dynamics, which could have broader ramifications for aquatic food webs and the provision of ecosystem services. 

Tessa Durnin (Primary Presenter/Author)
University of Minnesota, Twin Cities, durni018@umn.edu;

Debora Pires Paula (Co-Presenter/Co-Author)
Embrapa, debora.pires@embrapa.br ;

Leonard C. Ferrington, Jr. (Co-Presenter/Co-Author)
University of Minnesota, ferri016@umn.edu;

Abstract: Chironomidae that emerge in temperate regions during winter are less frequently studied as compared to summer-emerging counterparts. Two commonly encountered winter-emerging species, Diamesa nivoriunda Fitch and Diamesa mendotae Muttkowski have not been molecularly analyzed. Diamesa nivoriunda is widespread and well-defined morphologically. Diamesa mendotae is more restricted in distribution but more variable morphologically. Both species were collected in the southeastern Minnesota Driftless Area along four groundwater dominated trout streams during winter 2019-2020: Pine Creek, Clear Creek, Miller Creek, and the Vermillion River. Sixty-seven of 302 adults collected in December 2019 were randomly chosen for genetic analysis. Mitochondrial and nuclear DNA were extracted and barcode regions COI (154 bp), EF-1a (591 bp), and ITS (1044 bp) were amplified and Sanger sequenced. Multiple distinct sequences of Diamesa nivoriunda (12) and Diamesa mendotae (189) were differentiated across streams: Pine Creek (66), Clear Creek (54), Miller Creek (45), and Vermillion River (36). The number of unique sequences as a function of barcode regions were: 8 for COI, 3 for EF-1a, and 15 for ITS. The degree of differentiation of sequences suggest the presence of cryptic species within both morphologically defined species.

Andrew Wymore (Primary Presenter/Author)
The College of Idaho, andrew.wymore@yotes.collegeofidaho.edu;

Chris Walser (Co-Presenter/Co-Author)
The College of Idaho, cwalser@collegeofidaho.edu;

Abstract: Intermittent rivers and ephemeral streams are one of the most common, yet least studied types of aquatic ecosystems. Dry Creek, an ephemeral stream in southwestern Idaho, supports a genetically pure population of redband trout (Oncorhynchus mykiss). Our objective was to evaluate trout response to changing physicochemical conditions as stream flows decline. From June to September 2019, we used loggers to monitor stream temperatures and dissolved oxygen concentrations at 30-min intervals across 10 study reaches. We measured current velocity weekly, drifting macroinvertebrates were collected biweekly, while trout were sampled monthly at all reaches. Fish Condition Factor (K) was calculated to estimate fish health. We found current velocity decreased at all reaches. Mean daily water temperatures (6.4-22.3°C) were within an acceptable range for trout, but in late summer dissolved oxygen fell below the critical limit for trout (6.0mg/L). Across all reaches, rate of delivery of macroinvertebrates (number/15 min.) was significantly lower in August than June and July (p<0.05). Mean K for trout was significantly higher in July (1.25) than September (0.99) (p<0.05). We attribute this decline in trout condition to decreases in dissolved oxygen and macroinvertebrates brought upon by reduced stream flow.

Jake Wright (Primary Presenter/Author)
Wichita State University, wrightjake77@hotmail.com;

Abstract: Climate change is expected to increase the frequency and severity of droughts and precipitation events. Intermittent stream pools in the Great Plains present an idealized replicated system to study the impacts of variable climatic conditions on the distribution of aquatic species including amphibians. We sampled 117 stream pools to investigate the effects of fish presence, stream vegetation, hydroperiod, connectivity, and pool volume on larval amphibian distribution and density in the Flint Hills of Kansas. Fish presence, pool volume, and pool connectivity all influenced the distribution of amphibians on the landscape (P < 0.05). In pools where amphibian larvae occurred (n=31), density(g/m3) was significantly influenced by stream vegetation and pool volume (P < 0.01). In the Great Plains, intermittent stream pools are the most abundant spawning habitat for amphibians. We sampled during a wet year (2020) and the results we found are likely to be variable year to year due to the variation in precipitation. Although more precipitation has the potential to increase the likelihood of larval amphibian presence, it also makes pools more susceptible to fish colonization due to increased connectivity.

Leonard C. Ferrington, Jr. (Primary Presenter/Author)
University of Minnesota, ferri016@umn.edu;

Corrie Nyquist (Co-Presenter/Co-Author)
Lund University, Sweden, nyqui095@alumni.umn.edu;

Bruce Vondracek (Co-Presenter/Co-Author)
Department of Fisheries, Wildlife and Conservation Biology, University of Minnesota - Twin Cities, bvondrac@umn.edu;

Tessa Durnin (Co-Presenter/Co-Author)
Normandeau Associates, Inc., tdurnin@normandeau.com;

Hannah Bodmer (Co-Presenter/Co-Author)
University of Toronto Mississauga, hannah.bodmer@mail.utoronto.ca;

Abstract: Diamesa mendotae is a common winter-emerging insect in streams of southeast Minnesota, and forms a substantial component of trout diets. Adults collected on the snow are cold-tolerant, depress freezing points to ~-20° C, and are long lived when incubated at -10° C or 6° C. These attributes are interpreted as adaptively beneficial, increasing time for mate-location and reproduction under harsh and unpredictable weather conditions. However, what is not understood is if, or how, warmer winter air temperatures predicted by climate change models affect longevity. Adults collected on snow (n= 1,683) from streams in 2016-2019 were incubated at 0°, 6°, 12°, 18° and room temperatures (RT, 22°-24° C) to determine longevity under controlled lab conditions. We found statistically significant reductions in mean longevity, from 30.3 days (males) and 34.2 days (females) at 0° to 3.5 days (both sexes) at RT. Although treatments do not reflect realistic winter air temperatures, they suggest increasing winter temperatures have potential to reduce longevity of Diamesa mendotae, possibly resulting in less reproductive success. These studies also represent range-finding testing protocols to be used as reference data to set more realistic test conditions in subsequent experiments.

Raquel Arias Font (Primary Presenter/Author)
Univerisity of Birmingham, R.AriasFont@bham.ac.uk;

Abstract: Climate change is expected to intensify the frequency of extreme events, such as low flow and heatwaves, with potentially significant impacts for stream ecosystem functioning. Here, we examined the effect of low flow and heatwaves individually and combined on a suite of ecosystem processes in a stream mesocosm experiment. Habitat contraction was the main driver of reduced ecosystem functioning in the low flow treatment, suppressing metabolism, but elevating DOC concentration. By contrast, heatwaves increased decomposition, algal accrual, and humic-like DOC, but reduced leaf decomposition efficiency. Assessment of NEP responses to the three successive heatwave events revealed that responses later in the sequence were more similar to controls, suggesting that biofilm communities may acclimate to autumn heatwaves. However, when heatwaves co-occurred with low flow, a strong reduction in both ER and GPP was observed, suggesting increased microbial mortality and reduced acclimation. Our study reveals autumn heatwaves will potentially elongate the growth season for primary producers and stimulate decomposers. With climate change, river ecosystems may become more heterotrophic, with faster processing of recalcitrant carbon.

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

Mariely Vega-Gómez (Primary Presenter/Author)
North Carolina State University, mvega2@ncsu.edu;

Abstract: In the Caribbean, hurricanes and droughts alter resource availability for aquatic biota. Here, we evaluate the impact of these disturbances on freshwater ecosystems by assessing changes in functional feeding group (FFG) abundances in two streams (Quebrada Prieta A and B) of El Yunque National Forest, Puerto Rico. Puerto Rico was impacted by a drought in 2015, and two major hurricanes in 2017 (i.e. Irma and Maria). Quarterly (2014 – 2015) and monthly (2016 – 2018) macroinvertebrate sampling was conducted in pools using corers, and taxa were classified using FFGs. Analysis of similarity was performed to compare FFGs among pre-drought, post-drought, pre-hurricane, post-hurricane, and short-term post-hurricane periods. Scrapers and Collector-Gatherers dominated the assemblage during the sampling period in QPA and QPB, respectively. Average FFGs remained similar between pre-disturbance and post-disturbance groups. Shifting environmental conditions did not result in significant differences between groups, except for the pre-hurricane and short-term post-hurricane groups of QPA, where scraper taxa decreased. Overall patterns could suggest that FFG composition was resilient to these natural disturbances. A comprehensive understanding of how stream ecosystems respond to disturbances is critical to understand their vulnerability to predicted changes in environmental conditions.

Nicole Tripp (Co-Presenter/Co-Author)
University of Florida, tripp17@ufl.edu;

Jim Stoeckel (Co-Presenter/Co-Author)
Auburn University, jas0018@auburn.edu;

Lindsey Reisinger (Primary Presenter/Author)
University of Florida, lreisinger1@ufl.edu;

Abstract: Freshwater species are exposed to novel thermal regimes due to climate change and biological invasions. Temperature can alter the metabolic rates of ectotherms, which can affect their energy requirements, behavior, and ecological impacts. We used a widely distributed crayfish, the virile crayfish (Faxonius virilis), to examine the relationship between climate and crayfish metabolic rates and activity levels. We hypothesized that crayfish from high latitudes would have higher routine metabolic rates and activity levels as an adaptation to promote food acquisition during the short growing season. We collected virile crayfish from eight populations along a latitudinal gradient and used intermittent respirometry to measure crayfish routine metabolic rates in common conditions. In support of our hypothesis, there was a significant positive relationship between home latitude and crayfish metabolic rates, but this only occurred at night when crayfish are more active. Further, crayfish from higher latitudes had higher activity levels in behavioral experiments. These data suggest that the behavioral traits within this species shift as a response to the local thermal regime. Thus, future changes in the climate may result in changes in behavioral traits and associated metabolic rates.

Chris Patrick (Primary Presenter/Author)
Virginia Institute of Marine Science, cpatrick@vims.edu;

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

Matt Whiles (Co-Presenter/Co-Author)
University of Florida, mwhiles@ufl.edu;

Hannah Vander Zanden (Co-Presenter/Co-Author)
UF, hvz@ufl.edu;

Amber Ulseth (Co-Presenter/Co-Author)
Sam Houston State University, amber.ulseth@epfl.ch;

Bradley Strickland (Co-Presenter/Co-Author)
Virginia Institute of Marine Science, bastrickland273@gmail.com;

Connor Brown (Co-Presenter/Co-Author)
Sam Houston State University, clb150@SHSU.EDU;

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

Christopher Frazier (Co-Presenter/Co-Author)
Texas A&M Corpus Christi, christopher.frazier@tamucc.edu;

Christopher Groff (Co-Presenter/Co-Author)
Texas A&M Corpus Christi, cgroff@islander.tamucc.edu;

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

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

Abstract: Changes in rainfall patterns worldwide are one of the predicted effects of global climate change, causing entire regions to become wetter or drier over the next century. The tight linkages between rainfall and hydrology make streams extremely vulnerable to these types of changes, however, forecasting the impacts of changes in rainfall on streams is extremely challenging. Precipitation is not conducive to lab experiments, and observational studies along rainfall gradients typically have variables like temperature, elevation, and underlying geology covarying with rainfall. However, the Texas Coastal Plain is a natural precipitation gradient without natural covarying variables. Here, we present information from six years of monitoring and experiments in this region assessing the effect of rainfall on stream ecosystem structure and function and describe the next phase in this work, an assessment of drivers of primary and secondary production along the rainfall gradient. Whereas variables like hydrologic variability and algal abundance changed gradually, others such as ER/GPP showed little change, and the composition and stability of fish and invertebrate communities changed rapidly in the middle of the gradient.

Melinda Martinez (Primary Presenter/Author)
North Carolina State University, mmarti13@ncsu.edu;

Marcelo Ardon (Co-Presenter/Co-Author)
North Carolina State University, mlardons@ncsu.edu;

Abstract: The southeastern US coastline has seen an increase in extensive tree mortality (i.e. ghost forests) due to climate change variability and human activities. Ghost forests are areas that were healthy forested wetlands in the past, but are now transitioning to marshes or open water. Critical transitions occur when ecosystems become increasingly fragile to disturbances, to the point where a small perturbation may trigger a change to a new state. As freshwater forested wetlands transition to other wetland types, the ecosystem services provided become reduced or altered. Given the potential loss of ecosystem services, it is important to anticipate when and where critical transitions are likely to occur, but it has been challenging to map these transitions, which has limited mitigation efforts. Remote sensing imagery is a valuable method to detect critical transitions early at the necessary temporal scale due to repeated and consistent observations over large spatial extents. In this study, early warning signals of critical transitions were assessed using the LandTrendr algorithm and metric-based indicators by assessing each pixel’s ability to recover from a disturbance over time.

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

Brandi Kiel Reese (Co-Presenter/Co-Author)
Dauphin Island Sea Lab, bkielreese@disl.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;

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

Abstract: Local precipitation regimes are predicted to be affected by global climate change. We surveyed nine streams in the Texas Gulf Coastal Prairie that were distributed across a semi-arid to sub-humid rainfall gradient to observe the ecological impact of differing precipitation regimes. On a monthly basis, we assessed benthic invertebrate community characteristics, flow conditions, and water quality variables to relate precipitation regime to stream ecosystem structure and function. As annual rainfall increased, flow regimes became more stable within seasons and predictable across seasons. Invertebrate community composition was influenced by rainfall and correlated flow variables. Sub-humid streams were dominated by slower growing taxa without adaptations for desiccation resistance and strong dispersal. In contrast, semi-arid streams with lower, more stochastic flows were dominated by taxa with the ability to exit the water. Mesic sites displayed greater seasonal variation in composition and species richness than semi-arid sites, whereas the communities in semi-arid sites were strongly shaped by flow conditions in the weeks prior to sampling. These observations demonstrate how important precipitation regime is to stream ecosystem structure and function, suggesting that climate change may have sweeping impacts on lotic fauna.