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Introduction

Methodology

THE EFFECT OF RECRUITMENT OF OYSTERS (CRASSOSSTREA VIRGINICA) AND OTHER REEF ORGANISMS BASED ON SITE AND TIDAL LOCATION

Reyes Umanzor Jr¹, Dr. John Carroll²

¹Department of Marine Science, University of Connecticut, Storrs Mansfield, CT

²Department of Biology, Georgia Southern University, Statesboro, GA

Study Area

Acknowledgements

How is the recruitment of reef organisms dependent on water quality and tidal location on Sapelo Island?

Central Question

Discussion

This research was sponsored by the National Science Foundation (NSF) and Georgia Southern University. NSF Award DBI 2244232. Many thanks to Wil Atencio, Jessie Rivera, Zach Czoer, and Skyler Fox for their assistance in the lab and field. Another thanks to Wil for his predation experiment data.

Results

Figure 2. Satellite imagery of Sapelo Island, GA highlighting roads and developed

areas. Deployment sites used during the experiment are noted on the map, along

with images of each corresponding site.

Hunt Camp

Ferry Dock

Cabretta Creek

Addition of more sites to deploy tiles

Broader array of water quality conditions

Measurement of more water quality variables

Sediment type, water flow, predation

Utilization of a more secure method of attachment of tiles onto bricks
Deployment of tiles during different seasons throughout the year

Future Steps

Open Water

Dry Land

Tidal Range

Field

Sites were chosen due to SWMP data collected over the past ten years
At each site, a split was made between low-tidal location and mid-tidal location

Eight bricks attached with limestone tiles were placed at each tidal location during low tide

Bricks were left and collected after a full lunar tidal cycle (28 days)
Tiles were then removed from bricks and brought to lab for processing

Eastern oysters are a major keystone species in ecosystems

Allow for habitat building, water filtering, & prevent erosion

Sapelo Island, GA is a barrier island off the Atlantic Coast benefitting from these oysters
Sites experience unique marsh environments monitored by system-wide monitoring program (SWMP)
Recruitment of organisms increases abundance in ecosystems, aiding in potential recovery after disruption

Figure 3. Diagram showing the positioning of the bricks relative to the lower (left) and mid (right) tidal range of each site.

Figure 4. (A) Overhead photo of all 96 tiles used during the experiment, including attached oysters. (B) Photo of myself out at Hunt Camp. (C) Photo of brick and tile before month-long deployment. (D) Photo of different brick and tile after month-long deployment.

Figure 1. Graphs of the (A) salinity, (B), temperature, (C) DO, and (D) pH of the four sites collected over the past ten years by SWMP

● Cabretta Creek, ● Dean Creek, ● Hunt Camp, ● Ferry Dock

Tiles are sorted and organized based on site and tidal location
Any debris (algae) or sediment get gently rinsed off with water
Tiles get placed in a drying oven at 60°C for 48 hours
Recruitment of four different organisms were counted: oyster, barnacles, worms, and bryozoans

Figure 5. Photo back at the lab, after tiles have been cleaned up counted for recruitment of species such as (A) oysters, (B) barnacles, (C) worms, and (D) bryozoans

Lab

Dean Creek

Site	Salinity	DO	pH	Temperature
Cabretta	32.12 ± 0.95	5.02 ± 1.50	7.69 ± 0.21	29.27 ± 1.58
Hunt	24.73 ± 1.22	3.64 ± 0.89	7.22 ± 0.10	29.73 ± 1.96
Dean	27.81 ± 1.47	3.42 ± 1.70	7.36 ± 0.25	29.39 ± 1.95
Ferry	24.20 ± 1.92	5.11 ± 0.68	7.58 ± 0.17	29.11 ± 1.11

Low-tidal location is better for recruitment than mid-tidal location
Each site (-Cabretta) had more of one type of species than the others

Dean Creek – Oysters
Hunt Camp – Barnacles
Ferry Dock – Bryozoans

Differing water quality conditions may have affected the type of organism recruitment (i.e. pH, DO, salinity)
Unmeasured conditions also may have come into play

Predation of oysters has been studied at the same four sites

Figure 6. (A) Bar graph showcasing the overall mean recruitment of the four species across the four sites, split between the low and mid tidal locations. (B) Bar graph showcasing the overall mean recruitment of solely oysters across the four sites, split between the low and mid tidal locations. Error bars represent standard deviation.

● Worms, ● Barnacles, ● Oysters, ● Bryozoans

	Cabretta Creek		Dean Creek		Hunt Camp		Ferry Dock
Organism	Low	Mid	Low	Mid	Low	Mid	Low	Mid
Oyster	3.25 ± 4.50	2.08 ± 4.23	18.67 ± 17.29	8.68 ± 9.10	5.57 ± 3.13	0.99 ± 2.49	7 ± 3.13	4.71 ± 3.13
Barnacle	1.38 ± 2.88	0.92 ± 2.78	0.33 ± 1.00	0 ± 0	12.71 ± 14.58	6.82 ± 21.62	0.10 ± 0.32	0 ± 0
Worm	1.75 ± 1.58	0.54 ± 1.66	0 ± 0	0 ± 0	0 ± 0	0 ± 0	8.0 ± 4.69	1.86 ± 2.34
Bryozoan	3.63 ± 3.66	2.92 ± 8.77	0.22 ± 0.67	0 ± 0	0 ± 0	0 ± 0	38.1 ± 9.34	26.71 ± 22.47

Figure 7. (A) Table showing the mean and standard deviation values of the different water quality conditions across the four sites throughout Summer 2024. (B) Table showing the mean and standard deviation values of the different recruitment done by the four species, separated by site and tidal location.

Figure 8. Data from a separate predation experiment showcasing the mean survival of oysters left out on traps on the four same sites used during this experiment