Date of Award

Spring 5-6-2022

Document Type

Thesis

Degree Name

Bachelor of Science (BS)

Department

Marine Science

College

College of Science

First Advisor

Juliana M. Harding

Abstract/Description

Temperate estuaries are important habitats for resident species and maturing juvenile transient fishes. The North Inlet estuary, SC resident fish fauna includes the Striped Blenny (Chasmodes bosquianus) and Crested Blenny (Hypleurochilus geminatus). Individual blenny males occupy habitat shelters year-round. During breeding season, blenny males attract mates to nest and protect developing embryos within the nest. Salinity requirements establish blenny spatial distribution in the estuary. Seasonal spawning activity by these temperate blenny species is related to water temperature and seasonal productivity patterns. Blenny nest site occupancy patterns relative to the lunar cycle, water depth, and salinity were quantified during 2020 and 2021 in North Inlet estuary, SC. Underwater video cameras recorded diel blenny activity in and around nest sites from early April until July in 2020 and 2021. Salinities remained above the lower blenny survival threshold throughout the observation period. Male blenny residents were present in nest shelters during 56.8% of the April to July observation period. Female blenny were also present for at least some portion of each observation day within this time period. Male blenny mating displays, female blenny nest shelter visits, or both kinds of mating activity were observed on 141 out of 178 observation days between sunrise and sunset. Male and female Striped Blenny exhibited the most nesting activity (8.2%) in the early mornings before 07:00 with nesting activity decreasing after sunrise until reaching a daily low at approximately 15:00. The most nesting activity by either blenny sex occurred during early ebb tide. Male Striped Blenny nesting behavior was significantly higher seven days after the new moon. Female Striped Blenny nesting activity was significantly higher 7-9 days before the new moon. The positive relationship between Striped Blenny nesting activity and increasing moonlight that optimizes light required to see breeding coloration and displays while minimizing predation risk at higher light levels is similar to documented trends in coral reef blenny mating behavior. Synchronization of temperate blenny reproductive cycles with lunar cycles likely optimizes their reproductive success in estuaries and their contributions as intermediate species in the ecosystem food web.

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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