Fish assemblages across a vegetation gradient in a restoring tidal freshwater wetland: diets and potential for resource competition

• Published in: Environmental biology of fishes Vol. 97; no. 6; pp. 659 - 674
• Main Authors: Whitley, Sarah N, Bollens, Stephen M
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer-Verlag 01-06-2014; Springer Netherlands; Springer; Springer Nature B.V
• Subjects: Agnatha. Pisces; Animal and plant ecology; Animal Systematics/Taxonomy/Biogeography; Animal, plant and microbial ecology; Animals; Autoecology; Biological and medical sciences; biomass; Biomedical and Life Sciences; Diet; Endangered species; Environment; Fish; Fresh water ecosystems; Freshwater; Freshwater & Marine Ecology; Freshwater ecology; Fundamental and applied biological sciences. Psychology; General aspects; gillnets; Habitats; Life Sciences; Morone saxatilis; Nature Conservation; Percina caprodes; Predation; salt marshes; Seasons; Spring; statistical analysis; stomach; summer; Synecology; Tidal waves; Vegetation; Vertebrata; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; Water resources management; Wetlands; Winter; Zoology; Zooplankton; California; INE, USA, California; Competition; Fish ecology; Wetland restoration; Diet; Tidal marsh; Resource partitioning; Brackish water environment; Ecology; Resource sharing; Tides; Feeding; Freshwater environment; Salt marsh; Resource repartition; Vertebrata; Animal community; Pisces; Vegetation; Ecological recovery; Wetland
• DOI: 10.1007/s10641-013-0168-9
• EISSN: 1573-5133
• ISSN: 0378-1909

Marsh habitats have been the focus of recent worldwide restoration efforts due to their degradation and destruction as a result of human development. We assessed fish resource use at a naturally restoring marsh (Liberty Island, California, USA) by comparing diet composition, stomach fullness, normalized stomach weight, and diet overlap across a vegetation gradient. Fish were collected using gill nets and fyke nets at six sites during spring 2010, summer 2011 and winter 2012. We analyzed 392 stomachs from the eleven most abundant species collected. Prey composition and biomass varied seasonally for all fish species, but there were no notable differences across sites or seasons for stomach fullness or normalized stomach weight for most fish species. Results from non-metric multidimensional scaling (NMDS) and two-way analysis of similarities (ANOSIM) indicated minimal diet overlap between species (R = 0.633, p = 0.001) and seasons (R = 0.413, p = 0.001). Seasonal habitat and resource use across the vegetation gradient was species-specific. Small but significant spatial diet differences were detected for inland silverside, striped bass and bigscale logperch. Delta smelt exhibited seasonal diet differences by shifting from chironomids and zooplankton during spring, to amphipods and zooplankton during winter. More generally, fish maintained stomach fullness across all sites and seasons while maintaining minimal dietary overlap. Our study emphasizes the importance of tidal marshes as feeding habitat for several fish species, including the endangered delta smelt.