HCNSO Student Theses and Dissertations

Defense Date

7-2015

Document Type

Thesis

Degree Name

M.S. Marine Biology

Second Degree Name

M.S. Coastal Zone Management

First Advisor

Amy Hirons

Second Advisor

David Kerstetter

Third Advisor

Tracey Sutton

Abstract

Many marine fishes use the mangrove ecosystem for foraging, protection, spawning, and as a nursery habitat. To develop a better understanding of energy flow between the coastal mangrove and coral reef ecosystems, the ontogentic migration and trophic connectivity of reef fishes were examined through the use of carbon (C), nitrogen (N), and oxygen (O) stable isotope ratios. Juvenile and adult gray snapper Lutjanus griseus, lane snapper L. synagris, bluestriped grunt Haemulon sciurus, French grunt H. flavolineatum, sailor’s choice H. parra, yellowfin mojarra Gerres cinereus, and great barracuda Sphyraena barracuda were collected from both mangrove and coral reef sites located near Port Everglades, Broward County, Florida. All species were analyzed for δ13C and δ15N of muscle tissues and δ 18O and δ 13C of otoliths to evaluate ontogenetic migrations, foraging, and occupation within both the mangrove and reef sites. The δ13C and δ15N in muscle tissue were more depleted in juvenile fish from the mangroves than their adult forms caught on the adjacent reef. The δ18O and δ13C otolith data were significantly different between species, age class, and habitat, with lower δ18O values for juvenile fish caught in the mangroves. A general trend of increasing δ13C in otoliths corresponded to increasing total length, also suggesting juvenile movements from mangrove to nearshore reefs with age. Overall, the findings of this study further confirm that several commercially and recreationally important reef-associated fishes utilize mangrove ecosystems during juvenile life stages.

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