Date of Award

Spring 5-24-2023

Document Type

Undergraduate Honors Thesis

Department

Environmental and Ocean Sciences

Advisor

Dr. Drew Talley

Advisor

Dr. Bethany O'Shea

Abstract

Marsh restoration and creation are increasingly being used to mitigate Southern California’s drastic decline in wetlands due to human activities. This study used minnow traps to resample the ichthyofauna of a created marsh (Crown Point Mitigation Site; CPMS) and an adjacent natural marsh (Kendall Frost) in Mission Bay, California, 26 years following the marsh creation. Data from this study were compared to data collected immediately after marsh creation from 1995-1998, and from 2021. Fishes captured included Fundulus parvipinnis, Gillichthys mirabilis, Acanthagobius flavimanus, Ctenogobius sagittula, and Mugil cephalus. Species richness and dominance measures were higher in the natural relative to the created marsh. The size-structure of F. parvipinnis populations in the natural marsh were skewed towards larger sizes relative to those in the created marsh. These size differences were similar to 2021 but opposite of those noted in the years immediately following marsh creation, suggesting long-term changes rather than inter-annual variability. The changes in size-structure appear to arise from differences in creek morphology between the created and natural systems, with the created marsh creek having become shallower through time. To determine nutrient (nitrate and phosphate) concentrations, surface water samples were collected, filtered, and analyzed with a SEAL Analytical AQ400. No significant difference in nutrients were detected between the marshes. The differences in ichthyofaunal communities between the created and natural systems suggest that marsh/creek geomorphology may be affecting the suitability of habitat for resident fishes and should be more carefully considered when designing marsh restoration projects.

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