COS 185-5 - Size-based intraspecific trait variation-diversity relationships in freshwater fish across National Ecological Observatory Network (NEON) streams and lakes

Wednesday, August 9, 2023

2:30 PM – 2:45 PM PDT

Location: B110

Presenting Author(s)

AM

Alicia McGrew

Post-doctoral Fellow
Institute for Watershed Studies, Western Washington University
Bellingham, Washington, United States

Coauthor(s)

CG

Crysta Gantz

Institute for Watershed Studies, Western Washington University / Department of Environmental Science and Management, Portland State University, United States
BW

Brigid Wills

Western Washington University, United States
LK

Lala Kounta

Michigan State University, United States
AS

Angela Strecker

Associate Professor
Institute for Watershed Studies, Western Washington University
Bellingham, Washington, United States
BB

Benjamin Baiser

Associate Professor
Department of Wildlife Ecology and Conservation, University of Florida
Gainesville, FL, United States
SR

Sydne Record

Associate Professor
Department of Wildlife, Fisheries, and Conservation Biology, University of Maine, Maine, United States
PZ

Phoebe L. Zarnetske

Associate Professor
Department of Integrative Biology; Ecology, Evolution, and Behavior Program; Institute for Biodiversity, Ecology, Evolution, and Macrosystems, Michigan State University, United States

Abstract: Body size is a fundamental trait shared by all organisms, serving as a proxy for species’ traits that govern species’ niches. While measures of species diversity (e.g., richness) describe the structure of communities, intraspecific trait variation (ITV) in body size can elucidate abiotic and biotic mechanisms that influence species’ niches to shape patterns of diversity. In freshwater fishes, a species’ niche and functional roles are strongly related to body size; however, drivers of fish diversity and its relationship to trait variation remain unclear, particularly across broad spatial scales. We leveraged data products from the National Ecological Observatory Network’s (NEON) aquatic observation and instrument systems to understand drivers of fish diversity in 17 streams and lakes in the continental United States. We explored the direct and indirect influences of local-scale abiotic and biotic processes on patterns of fish diversity through the lens of ITV in fish body size. For each NEON site, we calculated 1) within-site pairwise size overlap for fish species and subspecies length and weight distributions, 2) taxonomic richness and phylogenetic diversity, and 3) pairwise metrics of phylogenetic structure. While body size overlap values can range from 0-1 (i.e., no overlap to complete overlap), observed overlaps were moderate and ranged from 0.24 to 0.73 for fish length and 0.18 to 0.71 for fish weight. Site-level taxonomic richness ranged from 2 to 23 taxa, and measures of phylogenetic diversity ranged from sites with few, closely related taxa to sites to sites with many, relatively distantly related taxa. We quantified relationships between body size overlap with local abiotic factors (climate, productivity, disturbance) by analyzing their direct and indirect (i.e., through size overlaps) influence on measures of fish diversity using path analysis. Local abiotic factors act directly and indirectly on fish diversity via intraspecific trait variation through mechanisms such as environmental filters, partitioning of available niches among species, and size-based competitive interactions. Understanding the proximate and ultimate factors that affect relationships between species traits and patterns of diversity in freshwater fish is important for understanding current and future impacts to freshwater communities and ecosystems.