Date of Award

Spring 5-1-2023

Document Type

Thesis

Degree Name

Master of Science in Coastal Marine and Wetland Studies

Department

Coastal and Marine Systems Science

College

College of Science

First Advisor

Dan Abel

Second Advisor

Robert F. Young

Third Advisor

Matthew Kimball

Additional Advisors

Eric Rosch

Abstract

Urbanization near estuaries has been shown to affect the growth and survival of juvenile sharks using the system as a nursery. North Inlet and Murrells Inlet, South Carolina, are similarly-sized, tidally-dominated, bar-built estuaries with extensive Sporobolus-lined tidal creeks but differ in degree of human impact. Previously, Murrells Inlet was shown to have a lower abundance and diversity of large sharks than North Inlet and Atlantic Sharpnose Sharks (Rhizoprionodon terraenovae) were shown to use North Inlet as a primary nursery. To examine potential differences in neonate shark abundance and growth between a developed estuary, Murrells Inlet, and a protected estuary, North Inlet, fifty-two neonate R. terraenovae were captured on hook-and-line gear from May to September 2022. Sharks were measured for length and girth, weighed, sexed, and released. Noise pollution between the two estuaries was investigated using hydrophone recordings. Relative abundance of neonate R. terraenovae was much greater for North Inlet (n = 45) than for Murrells Inlet (n = 7). However, body condition, weight-length relationships, girth-length relationships, and growth rates of the neonate sharks did not differ between the estuaries. Elasmobranch diversity was greater for Murrells Inlet than North Inlet, though bony fish diversity was equal between estuaries. Analysis of sound found no difference in the total loudness of the recordings between estuaries or the sound power of the recordings for shark hearing frequency ranges (p = 0.57, p = 0.45, respectively). Sampling sites were deeper for North Inlet and there was more boat traffic at Murrells Inlet, however, there was no correlation between the sound recordings and depth or boat traffic for either estuary. Although the difference in urbanization between estuaries did not affect the growth and body condition of R. terraenovae, the drivers behind the difference in abundance of neonates are still unclear.

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