Date of Award

Spring 5-5-2023

Document Type

Thesis

Degree Name

Bachelor of Science (BS)

Department

Marine Science

College

College of Science

First Advisor

Juliana M. Harding

Abstract/Description

Salt marsh tidal creek estuaries act as a nursery habitat for young transient nektonic species until individuals are mature enough to survive in other coastal habitats. Tidal creeks specifically provide refuge for young nekton by separating smaller individuals that may survive in shallower water depths from larger predators that must remain in deeper channels. Tidal creek geomorphology influences demographics and growth rates of estuarine-dependent juvenile nekton. Spot (Leiostomus xanthurus) was used as a model species to assess potential creek-specific differences in age-at-length and growth rates during 2022. Spot have high fidelity for specific tidal creeks during their first year as well as otoliths that include daily growth lines. Juvenile Spot were collected from two tidal creeks in North Inlet estuary, S.C. during low tide on July 15, 2022. Spot standard length was measured when otoliths were dissected from each fish (n >20 for each creek). Lapilli were mounted on slides so that daily growth lines could be exposed by sanding. The resulting line counts were used to determine the age-at-length and corresponding growth rates for individuals. Only fish with otolith count coefficients of variation <5% were used for analysis. Juvenile Spot standard length ranged from 37-61 mm in West Prong creek, and from 38-65 mm in North Jones creek. The median age of juvenile Spot in West Prong creek was 118 days, while the median age of juvenile Spot in North Jones creek was 122 days. Two cohorts were found in both West Prong and North Jones tidal creeks. The estimated growth rate for West Prong creek cohort 1 (0.57 mm/day, n = 4 fish) was statistically similar to the estimated growth rate observed in cohort 2 (0.65 mm/day, n = 12 fish). Estimated growth rates for North Jones creek cohort 1 (0.64 mm/day, n = 8 fish) were similar to the growth rates observed in cohort 2 (0.69 mm/day, n = 7 fish) at the same location. Growth rates observed in 2022 in both cohorts were similar across creeks. North Inlet spot growth rates in 2022 were comparable to those previously observed in North Carolina, South Carolina, and Virginia nursery habitats. Studying the age and growth of juvenile Spot resident in southeastern estuaries can help scientists to better understand optimal conditions for growth of this ecologically and commercially important species.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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