SFS Annual Meeting

6/04/2024  |   10:30 - 10:45   |  Philadelphia Ballroom

Long-term data reveal widespread phenological change across major U.S. estuarine food webs Climate change is shifting the timing of organismal life-history events such as hatching, growth, reproduction, and migration. Although consequential food-web mismatches can emerge if predators and prey shift at different rates, research on phenological shifts has traditionally focused on single trophic levels. Here, we gathered >2000 long-term, monthly time series of phytoplankton, zooplankton, and fish abundance or biomass for three major U.S. estuaries (San Francisco, Chesapeake, and Massachusetts bays) generated by local, state, and federal monitoring efforts. With these data, we constructed trivariate metaregression models that jointly model phenology, climate (temperature and salinity), and the relationship between the two. We found that phenological shifts occurred in over a quarter (27%) of the combined series and shifting taxa overwhelmingly advanced phenology. However, phenological trends for many (~34%-68%) taxa did not track the changing environment, and trends often diverged between predators and their potential prey. Unlike the expected pattern of phenological advancement displayed by fishes in the Chesapeake, fishes in the San Francisco Bay most often showed a delayed timing of peak abundance. When coupled with strong advancement of peaks for zooplankton, these phenological patterns illustrate the potential for climate-driven trophic mismatch. Our results suggest that even if signatures of global climate change differ locally, widespread phenological change has the potential to disrupt estuarine food webs.

Robert Fournier (Primary Presenter/Author), University of California, Berkeley, robertfournier@berkeley.edu;

Denise Colombano (Co-Presenter/Co-Author), Delta Stewardship Council, Denise.Colombano@deltacouncil.ca.gov;

Robert Latour (Co-Presenter/Co-Author), Virginia Institute of Marine Science, latour@vims.edu;

Stephanie Carlson (Co-Presenter/Co-Author), Department of Environmental Science, Policy, and Management, University of California, Berkeley, California, U.S., smcarlson@berkeley.edu;

Albert Ruhi (Co-Presenter/Co-Author), Department of Environmental Science, Policy, and Management, University of California, Berkeley, albert.ruhi@berkeley.edu;

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6/04/2024  |   10:45 - 11:00   |  Philadelphia Ballroom

Human impacts mediate invertebrate community responses to and recovery from drought Drought is an increasing risk to the biodiversity within rivers—ecosystems already altered by human impacts. However, long-term spatially replicated studies—which are needed to better understand how anthropogenic stressors alter ecological responses to drought—are lacking. To fill this gap, we collated aquatic invertebrate communities from 179 sites on rivers fed by England’s chalk aquifer collected as part of national biomonitoring over three decades. We assessed community responses to and recovery from drought in interaction with human impacts, including water quality, fine sediment, channel morphology, flow alteration (by abstraction and effluent) and temporal change in land use. Drought-driven reductions in taxa richness were exacerbated by low water quality, and changes in community composition impacted by water abstraction and land-use changes. Recovery from drought was lower at sites impacted by water abstraction and higher at sites with effluent-augmented flows, in particular as recovery trajectories extended beyond three years. Recovery was also enhanced at sites that had gained woodland and where cropland replaced pasture. Our use of long-term, spatially replicated data enabled detection of linear and non-linear responses, highlighting the potential for drought and human impacts to drive unexpected and sometimes abrupt community shifts. Our results show that communities in river ecosystems exposed to human impacts—in particular water quality, altered flow volumes and land-use change—are particularly vulnerable to drought. These findings demonstrate that national monitoring data—collected to assess the health of England’s rivers—can also generate new insights into concurrent ecosystem responses to climate change and human impacts.

Romain Sarremejane (Primary Presenter/Author), Nottingham Trent University, romain.sarremejane@gmail.com;

Judy England (Co-Presenter/Co-Author), Environment Agency, judy.england@environment-agency.gov.uk;

Rosalind Brown (Co-Presenter/Co-Author), Environment Agency, rosalind.brown@environment-agency.gov.uk;

Mike Dunbar (Co-Presenter/Co-Author), Environment Agency , mike.dunbar@environment-agency.gov.uk;

Rachel Stubbington (Co-Presenter/Co-Author), Nottingham Trent University, rachel.stubbington@ntu.ac.uk;

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6/04/2024  |   11:00 - 11:15   |  Philadelphia Ballroom

30 YEARS OF MACROINVERTEBRATE MONITORING IN THE NETHERLANDS REVEALS THE IMPACT OF CLIMATE CHANGE ON LOWLAND STREAMS The Dutch water authorities monitor macroinvertebrates in lowland streams following standardized sampling protocols. To date, this has resulted in an extensive dataset for streams in the Netherlands with over 10,000 samples from 235 watersheds for the period 1990-2020. This monitoring data has been primarily used to assess and report the waterbodies' ecological status according to the EU Water Framework Directive (WFD) guidelines in ecological quality classes ranging from ‘bad’ to ‘very good’. The currently used assessment method thereby provides water authorities insight into general degradation, but does not identify the underlying stressors that have determined the ecological status over time. More information on changes in the stressors may be obtained by using the ecological preferences of the macroinvertebrate species in the samples. Hence, our aim was to identify these stressor-specific trends. Based on the changes in the macroinvertebrate assemblages we showed that organic matter pollution decreased in most streams since the ‘90s, in line with improved collection and treatment of wastewater. In contrast, there was more stress related to drought and higher water temperatures in most streams. Despite the extensive amount of restoration efforts aiming at improving the flow conditions in streams, the effects regarding flow were mixed, with less stress from stagnation in about half of the streams and more stress in the other streams. In conclusion, 30 years of macroinvertebrate monitoring in the Netherlands reveals climate change as a significant pressure with an increasing impact on the assemblages of streams.

Gea van der Lee (Primary Presenter/Author), Wageningen Environmental Research, gea.vanderlee@wur.nl;

Ralf C.M. Verdonschot (Co-Presenter/Co-Author), Wageningen Environmental Research, ralf.verdonschot@wur.nl;

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6/04/2024  |   11:15 - 11:30   |  Philadelphia Ballroom

WHAT CAN LONG-TERM MONITORING DATA TELL US ABOUT THE INFLUENCE OF WILDFIRE ON STREAM HABITAT IN THE PACIFIC NORTHWEST? Long-term monitoring datasets provide valuable opportunities to identify aquatic ecosystem responses to disturbance at broad spatial extents. The Aquatic and Riparian Effectiveness Monitoring Program (AREMP) is unique in this regard because the program re-surveys the same 1411 stream sites in the Pacific Northwest on an 8-year return interval. Regular return surveys provide snapshots of stream habitat conditions that bookend disturbance events, such as wildfire. We focus on pre- and post-fire changes for in-stream large wood at 84 sites, as large wood is a component of habitat complexity potentially impacted by wildfire. Post-fire change in large wood metrics was variable. Wood frequency increased at 40% of sites and decreased at 38% of sites; log jam occurrence increased at 11% of sites and decreased at 10% of sites. We use Random Forest models to assess large wood responses to burn severity and time since fire within context of initial wood availability, watershed drainage area, topography, forest age, and post-fire high flows. We highlight the utility of pre- and post-fire measurements to identify changes in stream habitat within the 8-year windows of AREMP surveys. Ongoing work will incorporate change-over-time for stream habitat metrics at sites where fire has not occurred in the recent past, facilitating understanding of fire effects within context of climate and anthropogenic disturbances in the Pacific Northwest. The views expressed in this abstract are those of the authors and do not necessarily represent the views or policies of the U.S. Environmental Protection Agency.

Robert Brown (Primary Presenter/Author), Oak Ridge Institute for Science and Education (US EPA), brownrs1991@gmail.com;

Sara Wall (Co-Presenter/Co-Author), Oak Ridge Institute for Science and Education (USFS), sara.wall@usda.gov;

Marcía Synder (Co-Presenter/Co-Author), US Forest Service, marcia.snyder@usda.gov;

Christine Hirsch (Co-Presenter/Co-Author), US Forest Service, christine.hirsch@usda.gov;

David Hockman-wert (Co-Presenter/Co-Author), US Forest Service, david.hockman-wert@usda.gov;

Rebecca Flitcroft (Co-Presenter/Co-Author), USDA Forest Service, PNW Research Station, rebecca.flitcroft@usda.gov;

Joe Ebersole (Co-Presenter/Co-Author), US EPA, Western Ecology Division, Corvallis, OR, ebersole.joe@epa.gov;

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6/04/2024  |   11:30 - 11:45   |  Philadelphia Ballroom

ESTIMATING ECOLOGICAL VULNERABILITY TO DROUGHT: A CASE STUDY IN THE SIERRA NEVADA, CALIFORNIA Most drought assessments are incomplete because they lack indicators of ecological vulnerability. Further, it is unclear which of the plethora of hydro-meteorological indicators of drought are most relevant to ecological wellbeing. Our objectives were to estimate drought vulnerability for streams and rivers at a regional scale and to identify the ecological relevance of hydrologic drought indicators. We hypothesized that at sites minimally influenced by land and water management, biological condition would be influenced by variation in drought severity. We used biological monitoring data collected by the California Department of Fish and Wildlife from 1999-2015 in the Sierra Nevada ecoregion. We computed 25 hydrologic drought indicators from modeled monthly runoff at each of 157 monitoring sites, which were combined with 71 geospatial indicators of basin topography, soils, geology, and groundwater dynamics. Models predicting biological condition using these explanatory variables performed well on calibration and validation datasets (true skill statistic = 0.79, 0.69, respectively). The most influential predictors were related to antecedent runoff and groundwater influence on streamflow. We offer example applications of the models for assessing spatial and temporal vulnerability to drought.

Daren Carlisle (Primary Presenter/Author), U.S. Geological Survey, dcarlisle@usgs.gov;

Andrew Rehn (Co-Presenter/Co-Author), California Department of Fish and Wildlife, Andy.Rehn@wildlife.ca.gov;

Eric Stein (Co-Presenter/Co-Author), Southern California Coastal Water Research Project, erics@sccwrp.org;

Kris Taniguchi-Quan (Co-Presenter/Co-Author), Southern California Coastal Water Project, Kristinetq@sccwrp.org;

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6/04/2024  |   11:45 - 12:00   |  Philadelphia Ballroom

Spatial and decadal-scale temporal changes in water chemistry and macroinvertebrates in central Alaska Northern latitudes are disproportionately warming due to climate change, with potential consequences cascading to aquatic life. We explored a data set of water chemistry and macroinvertebrate communities collected by the National Parks Service between the years 2004 and 2022, at ~225 sites in the Central Alaska Inventory and Monitoring Network (parks and preserves: Denali, Wrangell-St. Elias, and Yukon-Charley Rivers). Carbon and nitrogen (N) analyte concentrations typically decreased with increasing elevation. Although we detected site-specific trends in several water chemistry variables, total dissolved N consistently increased in almost all repeat visit sites, often from near detection limits (<0.005 mg/L) to 0.2 - 0.4 mg/L within two decades. Elevation was the dominant spatial driver of invertebrate richness. Site-specific richness trends ranged from 0 to a doubling of taxa (e.g., from ~20-40) within two decades. Further analysis will characterize community-level responses to spatial and temporal environmental gradients. These analyses establish baselines for monitoring in a rapidly changing Alaskan climate, as well as inform research priorities for understanding and forecasting future change.

Caleb J. Robbins (Primary Presenter/Author), University of Alaska Fairbanks, Caleb_Robbins@baylor.edu;

Trey Simmons (Co-Presenter/Co-Author), National Park Service, trey_simmons@nps.gov;

Jeffrey Muehlbauer (Co-Presenter/Co-Author), University of Alaska Fairbanks, USGS Alaska Cooperative Fish and Wildlife Research Unit, jdmuehlbauer@alaska.edu;

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