Hydrodynamics and habitat interact to structure fish communities within terminal channels of a tidal freshwater delta

• Published in: Ecosphere (Washington, D.C) Vol. 14; no. 1
• Main Authors: Huntsman, Brock M., Young, Matthew J., Feyrer, Frederick V., Stumpner, Paul R., Brown, Larry R., Burau, Jon R.
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.01.2023; Wiley
• Subjects: backwater slough; Cache Slough complex; Ecosystems; Estuaries; Fish; Fishing nets; Floods; Fluid mechanics; Food chains; Habitats; Influence; multivariate; Salinity; San Francisco Estuary; spatial scale; Stormwater management; tidal excursion; tidal marsh; Wetlands; United States > US; San Francisco California
• ISSN: 2150-8925; 2150-8925
• DOI: 10.1002/ecs2.4339

Terminal channels were historically a common feature of tidal delta ecosystems but have become increasingly rare as landscapes have been modified. Tidal hydrodynamics are a defining feature in tidal terminal channel ecosystems from which native aquatic communities have evolved. However, few studies have explored the relationship between fish community structure and hydrodynamics in these tidal terminal channel ecosystems. We sampled fish communities throughout a network of terminal channels within the northeasternmost region of the San Francisco Estuary to determine the relationship between fish community structure and hydrodynamics within these environments. We collected two years (2017 and 2018) of fish community samples using gill nets and analyzed data using multivariate community analyses and count models. We found metrics of fish diversity and counts of native fishes to be greatest upstream (farthest from tidal influence) of the tidal excursion within terminal channels. Counts of non‐native fishes were less affected by this hydrodynamic feature of terminal channels and more tightly correlated to local habitat conditions (e.g., water temperature, depth). Our results suggest that channel hydrodynamics plays a role in structuring fish communities within terminal channels, particularly native fishes. These results indicate that hydrodynamics in tidal delta ecosystems may be able to be altered in ways that benefit native fishes without the cost of water pumping.