West Florida Shelf pipeline serves as sea turtle benthic habitat based on in situ towed camera observations

C Lembke,Ha Broadbent,S Murawski,Rf Hardy,Km Hart,Se Grasty,Jl Brizzolara,Mm Lamont

doi:10.3354/ab00722

Abstract

The use of marine offshore benthic habitats by sea turtles is poorly characterized due to the difficulty of obtaining in situ data. Understanding benthic habitat use that is important to the species’ reproduction, foraging, and migrations is critical for guiding management decisions. A towed camera-based assessment survey system (C-BASS) equipped with environmental sensors was used to characterize and assess benthic habitats on the West Florida Shelf (WFS) from 2014 to 2018. During these cruises, sea turtles were opportunistically observed during the surveys, and critical in situ data such as spatiotemporal information, species identification, habitat use, behavior, and environmental data were collected and evaluated. In total, 79 sea turtles were observed during 97 transects of approximately 2700 km of seafloor, which was recorded on 380 h of video. Several sea turtle species were spotted within the WFS, including loggerhead Caretta caretta, Kemp’s ridley Lepidochelys kempii, and green turtles Chelonia mydas. These opportunistic sightings revealed an area of high use on the WFS, an anthropogenic structure known as the Gulfstream natural gas pipeline (GSPL). C-BASS survey results suggest that 2 sea turtle species (C. caretta and L. kempii) utilize this artificial structure primarily as a resting area. We emphasize the importance of combining habitat mapping techniques (towed underwater video and multibeam bathymetry/backscatter) with tracking technology to better understand the fine-scale habitat use of sea turtles.

Highlights

Most sea turtles spend a large portion of their lives underwater associated with distinctive habitats (Lutz et al 2002)
Characterizing the benthic habitat and developing methods to improve sub-surface sea turtle surveys is highly important to understanding sea turtle ecology
This research represents the first example of towed camera system data being used to characterize and study sea turtles in the Gulf of Mexico (GoM) at depths greater than 30 m (Zawada et al 2008)

Summary

Introduction

Most sea turtles spend a large portion of their lives underwater associated with distinctive habitats (Lutz et al 2002). These benthic habitats can include sea grass beds (green turtles; Ballorain et al 2010), coral reefs (hawksbills; Walcott et al 2014), natural rocky hard bottoms (loggerheads; Hart et al 2010), and rock outcroppings (Kemp’s ridleys; Schmid et al 2003). Distribution of sea turtles on the WFS has been associated with water temperature and benthic habitat features (natural and artificial) which aggregate prey (Fanning et al 1981, Foley et al 2014, Hardy et al 2014); this information is sparse and challenging to obtain (Stoneburner 1982). There has recently been a considerable emphasis placed upon the importance of habitat mapping (Brown et al 2011, Fakiris et al 2019) and a significant by-product of this research could be an increased amount of data on fine-scale sea turtle habitat use

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Discussion

Conclusion