Team Ocean diver Mike Mullinex rolls out the transect tape. (Photo: Laurie Bauer)
Today was another productive day. So far, we have successfully surveyed eight out of nine marine debris monitoring sites. Our efforts have been aided by calm seas; we couldn’t have asked for better weather!
The purpose of this project is to assess and monitor marine debris in Gray's Reef National Marine Sanctuary. Previously, we found that the incidence of the debris on densely colonized ledge was significantly greater than at sand or flat live bottoms. It is further influenced by the level of boating activity and ledge characteristics (e.g., ledge height). This information can be used to prioritize which ledges should be targeted for cleanup. However, one missing piece of the puzzle is the speed at which debris accumulates. This information would help determine how often sites should be cleaned.
Heavily encrusted debris removed from one of the survey sites. (Photo: Laurie Bauer)
To answer this question, we established nine permanent monitoring sites during last year’s Nancy Foster cruise. Ledges were selected to test two hypotheses: how does accumulation differ between a) short and tall ledges, and b) tall ledges residing in relatively low vs. high fishing areas. At each site, we measured out a 50m transect and marked either end with a sand anchor so that divers could find the site in the future. Any debris that was found within 2 meters on either side (for a total survey area of 200m2) was identified and removed. Notes on the association with the benthos (e.g., entanglement, negative impacts on biota, degree of fouling) were recorded.
Wire entangled in Oculina. (Photo: Laurie Bauer)
Currently, we are revisiting these sites to see what has accumulated over the past year. So far, we’ve found debris (including cable/rope, wire, and a fishing leader), at two sites, both of which are located in the part of the sanctuary that experiences higher fishing/boating activities. We’ve been accompanied by Team Ocean divers, Jeff Hart and Mike Mullinex, who have been trained in the survey protocol, which enables them to conduct the monitoring in the future. As an added “bonus”, we’ve been visited by many sea creatures at our sites, including a sandbar shark, nurse sharks, spiny lobster, and numerous scamp and gag grouper.