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SFS Annual Meeting

Wednesday, June 5, 2024
10:30 - 12:00

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S22 Leveraging the Whole Ecosystem Approach to Studying Freshwater Ecosystems: Celebrating the Career of Bill McDowell

10:30 - 10:45 | Philadelphia Ballroom | THE LONG ARC OF STREAM BIOGEOCHEMISTRY: CELEBRATING THE CAREER AND SCIENCE OF DR. BILL MCDOWELL

6/05/2024  |   10:30 - 10:45   |  Philadelphia Ballroom

THE LONG ARC OF STREAM BIOGEOCHEMISTRY: CELEBRATING THE CAREER AND SCIENCE OF DR. BILL MCDOWELL Professor Bill McDowell has emerged as a leader in the field of stream biogeochemistry over almost five decades. Although Dr. McDowell has made many scientific contributions (work on the nitrogen cycle, contributions to the Lotic Intersite Nitrogen Experiment (LINX), Long-Term Ecological Research (LTER), Critical Zone Observatories (CZO), and comparative analysis of urban, tropical, and forest ecosystems, his work on dissolved organic matter has distinguished him. Dr. McDowell’s first paper on the leaching of dissolved organic matter from leaves was in 1976 with Dr. Stuart Fisher. Dr. McDowell then worked on analyzing watershed sources, composition, and fluxes of organic matter for his PhD with Dr. Gene Likens. Later, Dr. McDowell worked with Dr. Jon Cole and collaborators on plumbing the global aquatic carbon cycle. Over decades, Dr. McDowell’s pioneering work has integrated the analysis of sources and composition of organic matter at watershed scales with downstream ecosystems. His research often crossed disciplinary divides unifying processes in soil science, atmospheric science, and geology with relevance to stream ecology and the aquatic sciences. Ultimately, McDowell’s research along with his collaborators has revolutionized the way that we conceptualize and study the aquatic carbon cycle and think of interdisciplinary science, long-term research, and critical zone observatories. In this special session, we will: (1) explore different and diverse themes associated with McDowell’s research, (2) discuss relevant emerging questions, and (3) celebrate the career and contributions of a visionary leader and eminent scientist, caring mentor, and dedicated citizen of our global freshwater science community.

Sujay Kaushal (Primary Presenter/Author), University of Maryland, skaushal@umd.edu;

Adam Wymore (Co-Presenter/Co-Author), University of New Hampshire, adam.wymore@unh.edu;

10:45 - 11:00 | Philadelphia Ballroom | THE RIPARIAN BIOME GRADIENT FRAMEWORK: GLOBAL CHARACTERIZATION OF TERRESTRIAL-AQUATIC ECOSYSTEM LINKAGES

6/05/2024  |   10:45 - 11:00   |  Philadelphia Ballroom

The riparian biome gradient framework: global characterization of terrestrial-aquatic ecosystem linkages Structure and function of riparian ecosystems varies with changing climatic and environmental conditions. Riparian zones are often distinct from the upland biomes they are embedded in because they are generally wetter (more consistent access to shallow saturated soils) and are carbon- and nutrient-rich. We define riparian biome gradients across five environmental axes that strongly determine their ecosystem properties: precipitation, temperature, seasonality, topography, and catchment position. We assess changes of key riparian properties including biodiversity, energy and carbon fluxes to aquatic ecosystems, water quality and quantity, aquatic habitat, and greenhouse gas production and carbon sequestration. Many of these functions are influenced by the presence of trees that shade small channels, serve as a carbon source, and provide habitat within and adjacent to streams. Very wet (potential evapotranspiration << annual precipitation) biomes have less distinct riparian zones, while drier biomes have riparian areas with denser, taller, and more productive vegetation than nearby uplands. Seasonality leads to forests with distinct periods of leaf and light input to streams, and fire coupled with seasonality can lead to the establishment of grasslands in riparian zones. Steep topography rapidly increases depth to the water table with distance from streams, narrowing streams and their riparian zones. Narrow streams are more influenced by riparian vegetation, but large rivers can have wide riparian areas. Understanding the drivers of riparian ecosystem function based on large-scale climatic patterns underlain by other factors is particularly important to predict terrestrial aquatic interactions in the face of global anthropogenic changes.

Walter Dodds (Primary Presenter/Author), Kansas State University, wkdodds@ksu.edu;

Ellen Wohl (Co-Presenter/Co-Author), Colorado State University, Ellen.Wohl@colostate.edu ;

Gilles Pinay (Co-Presenter/Co-Author), CNRS, gilles.pinay@ens-lyon.fr;

Tamara Harms (Co-Presenter/Co-Author), University of California Riverside, tharms@ucr.edu;

Li Li (Co-Presenter/Co-Author), The Pennsylvania State University, lxl35@psu.edu;

Jessica Corman (Co-Presenter/Co-Author), University of Nebraska-Lincoln, jcorman3@unl.edu;

Michael Gooseff (Co-Presenter/Co-Author), University of Colorado, michael.gooseff@colorado.edu;

Susana Bernal (Co-Presenter/Co-Author), Center for Advanced Studies of Blanes (CEAB-CSIC), Spain, sbernal@ceab.csic.es;

Sherri Johnson (Co-Presenter/Co-Author), U.S. Forest Service, Pacific Northwest Research Station, sherrijohnson@fs.fed.us;

Davi Cunha (Co-Presenter/Co-Author), University of São Paulo, davig@sc.usp.br;

Julian Olden (Co-Presenter/Co-Author), University of Washington, olden@uw.edu;

Lucas C. R. Silva (Co-Presenter/Co-Author), University of Oregon, lucascrsilva@gmail.com;

Pamela Sullivan (Co-Presenter/Co-Author), Oregon State University, Pamela.Sullivan@oregonstate.edu;

Corey Krabbenhoft (Co-Presenter/Co-Author), University at Buffalo, ckrabben@buffalo.edu;

Hélène Avocat (Co-Presenter/Co-Author), Kansas State University, havocat@ksu.edu;

11:00 - 11:15 | Philadelphia Ballroom | EFFECTS OF EXTREME DROUGHT ON RIPARIAN-STREAM CONNECTIONS WITH LITTER PROCESSING BY DECAPODS IN PUERTO RICAN HEADWATER STREAMS.

6/05/2024  |   11:00 - 11:15   |  Philadelphia Ballroom

Effects of extreme drought on riparian-stream connections with litter processing by decapods in Puerto Rican headwater streams. High temperature and fast rates of evapotranspiration increase rapid drying of riparian soils during droughts, resulting in synchronized leaf fall into pools with warmer water. The pulse of leaf-litter and rapid accumulations of detritus in warm, shallow pools leads to deoxygenation and movement of some shrimp from shallow pools to deeper pools. The leaching of nutrients and toxic chemicals from leaf litter can alter habitat quality among different pools increasing redistribution of detritivores. In contrast, high winds and intense rainfall during hurricanes cause defoliation of the forest canopy that results in longer storage of large inputs of leaf litter, primarily from Cecropia and Dacryodes, two dominant riparian trees. Detrital storage in debris dams is composed of woody materials and palm fronds. Slow downstream redeposition of leaf litter occurs in pools as the debris dams gradually break down. This process extends litter availability for detritivores for several months while canopy-cover regrowth occurs and daily litter inputs resume. The food availability initially from fast-decomposing, low-quality, fiber-rich Cecropia and later from slow-decomposing, microbially enriched Dacryodes leaf litter leads to increased numbers of detritivores per pool after the hurricanes relative to pre-hurricane numbers and pools remain deep with high dissolved oxygen during stream flows. Data from 1989 during Hurricane Hugo and 2017 during Hurricane Maria demonstrate these contrasting results relative to droughts in 2008 and 2015. The long-term cumulative effects of both hurricanes and droughts are expected to alter future distributions of shrimp detritivores (Atya lanipes, Xiphocaris elongata, Macrobrachium crenulatum, M. lanipes).

Alan Covich (Primary Presenter/Author), Odum School of Ecology, University of Georgia, a.covich@gmail.com;

Todd Crowl (Co-Presenter/Co-Author), Florida International University, facrowl@gmail.com;

Pablo E. Gutierrez-Fonseca (Co-Presenter/Co-Author), Rubenstein School of Environment and Natural Resources, University of Vermont, gutifp@gmail.com;

Alonso Ramirez (Co-Presenter/Co-Author), Department of Applied Ecology, North Carolina State University, alonso.ramirez@ncsu.edu;

Tamara Heartsill-Scalley (Co-Presenter/Co-Author), International Institute of Tropical Forestry, U.S.D.A. Forest Service, tamara.heartsill-scalley@usda.gov;

Omar Perez-Reyes (Co-Presenter/Co-Author), Department of Environmental Sciences, University of Puerto Rico, omar.perez@upr.edu;

Catherine Pringle (Co-Presenter/Co-Author), Odum School of Ecology, University of Georgia, cpringle@uga.edu;

Lauren Kabat (Co-Presenter/Co-Author), Institute of Environment, Florida International University , kabat.lauren@gmail.com;

Rolando Santos (Co-Presenter/Co-Author), Institute of Environment, Florida International University , rsantosc@fiu.edu;

Max Kelly (Co-Presenter/Co-Author), Odum School of Ecology, University of Georgia, maxkellyemail@gmail.com;

11:15 - 11:30 | Philadelphia Ballroom | LONG-TERM CHANGES IN NUTRIENTS, ORGANIC MATTER AND STOICHIOMETRY IN RIVERS DRAINING WATERSHEDS EXPERIENCING INCREASED DEVELOPMENT AND HYDROLOGIC VARIABILITY

6/05/2024  |   11:15 - 11:30   |  Philadelphia Ballroom

Long-term changes in nutrients, organic matter and stoichiometry in rivers draining watersheds experiencing increased development and hydrologic variability Long-term changes in watershed land cover, wet deposition, hydrologic variability, and wastewater management all affect stream chemistry and the delivery of organic matter, nutrients and sediments to coastal systems. Here we document long-term changes in nutrients, organic matter and stoichiometry in eight tributaries to the Great Bay Estuary in New Hampshire and Maine which is impaired by nitrogen and experiencing eelgrass habitat loss. Dissolved organic carbon (DOC), dissolved organic nitrogen (DON), dissolved inorganic nitrogen (DIN) and phosphate concentrations increased at several sites over the 15–20-year record. These changes occurred during a time (2010 - 2020) when the Great Bay watershed experienced a 6.4% increase in impervious cover (5.4% to 5.8%) and 9.7% increase in population (111 to 122 people per square kilometer). Improvements in wastewater management resulted in substantial declines in DIN at one site, but not DOC or phosphate. Little change is evident in carbon to nitrogen ratios, but a few sites show changes in nitrogen to phosphorus ratios. These results suggests that colored dissolved organic matter and nutrient loading delivered from the coastal watershed to Great Bay Estuary may continue to attenuate light (directly or indirectly) and threaten eelgrass habitat and overall ecological health.

Michelle Shattuck (Primary Presenter/Author), University of New Hampshire, Michelle.Shattuck@unh.edu;

William H McDowell (Co-Presenter/Co-Author), University of New Hampshire, bill.mcdowell@unh.edu;

Kalle Matso (Co-Presenter/Co-Author), Piscataqua Region Estuaries Partnership, Kalle.Matso@unh.edu;

11:30 - 11:45 | Philadelphia Ballroom | ASSESSING PARTICULATE QUANTITY AND BIOAVAILABILITY ACROSS A NESTED WATERSHED IN CENTRAL ALABAMA, USA

6/05/2024  |   11:30 - 11:45   |  Philadelphia Ballroom

ASSESSING PARTICULATE QUANTITY AND BIOAVAILABILITY ACROSS A NESTED WATERSHED IN CENTRAL ALABAMA, USA River networks are vital transporters and processors of dissolved and particulate [C]arbon, [N]itrogen, and [P]hosphorus and contribute disproportionately to the cycling and movement of these elements through the biosphere. However, most studies focus on the transport and transformation of dissolved forms of these elements, resulting in a limited understanding of the quality and quantity of particulate material exported along river continua. Here, we aimed to understand the controls on particulate C, N, and P within a nested watershed. We leveraged two years of biweekly data collection at three National Ecological Observatory Network (NEON) aquatic sites and two United States Geological Survey (USGS) sites in Alabama, USA. The three NEON sites were forested Mayfield Creek (MAYF, 14 km2), the Black Warrior River (BLWA, 16,160 km2), and the Tombigbee River (TOMB, 35,656 km2). The two USGS sites included the primarily urbanized Elliot’s Creek (ELL, 84 km2) and agriculture-dominated Crib’s Mill Creek (CRIB, 28 km2). At each site, we quantified particulate C, N, and P content and conducted ex situ respiration assays as a proxy for particulate quality. Across all sites, particulates contributed nearly one third (31.4%) of total respiration, driven by higher particulate respiration in the large-river sites, BLWA and TOMB (31.5% and 47.9%. respectively). The average molar particulate C:N:P ratio across all sites was 140:11:1. Our results suggest that the processes controlling particulate composition and biological activity within a watershed are complex. However, the dominant role of particulates in water-column respiration highlight their importance for elemental cycling across river networks.

Zacharie Loveless (Primary Presenter/Author), The Unversity of Alabama, ztloveless@crimson.ua.edu;

Arial Shogren (Co-Presenter/Co-Author), University of Alabama, ashogren@ua.edu;

Jonathan P. Benstead (Co-Presenter/Co-Author), The University of Alabama, jbenstead@ua.edu;

David Manning (Co-Presenter/Co-Author), University of Nebraska at Omaha, davidmanning@unomaha.edu;

11:45 - 12:00 | Philadelphia Ballroom | EFFECT OF AN EXPERIMENTAL FLOW REDUCTION ON A RAINFOREST STREAM ECOSYSTEM, PUERTO RICO

6/05/2024  |   11:45 - 12:00   |  Philadelphia Ballroom

EFFECT OF AN EXPERIMENTAL FLOW REDUCTION ON A RAINFOREST STREAM ECOSYSTEM, PUERTO RICO Climate change is altering precipitation regimes over the tropics and most of the Caribbean region is expected to experience more frequent periods of low precipitation and drought. Given that rainforest stream ecosystems are composed of biota adapted to continuous flow and frequent floods, prolonged periods of low flow might alter stream community structure and ecosystem function. We designed a flow reduction experiment to assess the effects of low flow conditions on stream fauna and ecosystem processes in Puerto Rico. Our goal was to determine the response of stream variables to recurrent low flow conditions. Our study was conducted within the Luquillo LTER research program at the Luquillo Experimental Forest, Puerto Rico. We used a pair of small headwater streams, manipulated flow in one and used the other as reference. Following climate model predictions, flow was reduced from March to July (the less rainy months) for two consecutive years. We collected monthly samples for algal biomass as chlorophyll a, benthic organic matter, leaf litter inputs, benthic and emerging insects, and shrimp. The flow reduction was effective in maintaining our experimental stream in low flow conditions, but large floods affected both streams. Algal biomass was maintained at low levels due to grazing and shrimp assemblages did not change in response to flow. In contrast, insect assemblage fluctuations reflected changes in flow. Overall, rainforest streams respond quickly to changes in flow, but biota is able to cope with low flow as long as dissolved oxygen is not depleted and temperature remains stable.

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

Pablo Gutiérrez-Fonseca (Co-Presenter/Co-Author), University of Costa Rica, pabloe.gutierrezfonseca@gmail.com;

Jesus Gomez (Co-Presenter/Co-Author), Department of Biology, University of Puerto Rico- Rio Piedras, jesuslobo06@gmail.com ;

Omar Perez-Reyes (Co-Presenter/Co-Author), Department of Environmental Sciences, University of Puerto Rico, omar.perez@upr.edu;

Catherine Pringle (Co-Presenter/Co-Author), Odum School of Ecology, University of Georgia, cpringle@uga.edu;

Todd Crowl (Co-Presenter/Co-Author), Florida International University, facrowl@gmail.com;

William McDowell (Co-Presenter/Co-Author), Department of Natural Resources and the Environment, University of New Hampshire, 03824, Durham, New Hampshire, bill.mcdowell@unh.edu;

Ana Meza-Salazar (Co-Presenter/Co-Author), North Carolina State University, ammezasa@ncsu.edu;

Vamery González-Hernández (Co-Presenter/Co-Author), Department of Applied Ecology, North Carolina State University, vgonzal5@ncsu.edu;

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