Deep-sea sponge grounds enhance diversity and abundance of epibenthic megafauna in the Northwest Atlantic

Abstract

Beazley, L. I., Kenchington E. L., Murillo, F. J., and Sacau, M. 2013. Deep-sea sponge grounds enhance diversity and abundance of epibenthic megafauna in the Northwest Atlantic. – ICES Journal of Marine Science, 70: . The influence of structure-forming deep-water sponge grounds on the composition, diversity, and abundance of the local epibenthic megafaunal community of the Flemish Pass area, Northwest Atlantic was statistically assessed. These habitats are considered vulnerable marine ecosystems and, therefore, warrant conservation measures to protect them from bottom fishing activities. The epibenthic megafauna were quantified from four photographic transects, three of which were located on the western slope of the Flemish Cap with an overall depth range of 444–940 m, and the fourth in the southern Flemish Pass between 1328 and 1411 m. We observed a diverse megafaunal community dominated by large numbers of ophiuroids and sponges. On the slope of the Flemish Cap, sponge grounds were dominated by axinellid and polymastid sponges, while the deeper sponge ground in the southern Flemish Pass was formed mainly by geodiids and Asconema sp. The presence of structure-forming sponges was associated with a higher biodiversity and abundance of associated megafauna compared with non-sponge habitat. The composition of megafauna significantly differed between sponge grounds and non-sponge grounds and also between different sponge morphologies. Surface chlorophyll a and near-bottom salinity were important environmental determinants in generalized linear models of megafaunal species richness and abundance.

Drivers of epibenthic megafaunal composition in the sponge grounds of the Sackville Spur, northwest Atlantic

“…Successive images were taken at one minute intervals along the drift course with the winch operator lifting the camera off-bottom after each image and hovering near-bottom until the next deployment. The area of seabed covered by the field of view of each image is 0.4770.05 m À 2 (mean7SD) (Beazley et al, 2013).…”

“…Voucher specimens collected using a rock dredge and box corer during the NEREIDA surveys onboard the RV Miguel Oliver aided taxonomic identification. Fauna that could not be identified to species were given mutually exclusive morphotype designations at a higher level following Beazley et al (2013). Organisms that could not be placed into a phylum were recorded as unidentified morphotypes (e.g., Unidentified 1).…”

“…Consequently, sponge grounds may exhibit a different and/or more diverse and abundant assemblage of associated fauna compared to non-sponge habitat (Bett and Rice, 1992;Kunzmann, 1996;Bo et al, 2012;Beazley et al, 2013;Kenchington et al, 2013). Sponge grounds can modify the physical and chemical structure of the surrounding seafloor through current baffling and sediment trapping (Krautter et al, 2006).…”

Shedding light on an East-Mediterranean mesophotic sponge ground community and the regional sponge fauna

“…Sponges are important habitat builders in the Mediterranean, creating complex three-dimensional structures, attracting fish and invertebrates by increasing the number and complexity of available microhabitats, providing refuge from predators, and serving as spawning and nursery grounds (Hogg et al, 2010;Beazley et al, 2013;Bo et al, 2012). They support local species richness and diversity and provide diverse ecosystem services, thus serving as environmental engineers Gerovasileiou et al, 2016).…”

Water mass characteristics and associated fauna of a recently discovered Lophelia pertusa (Scleractinia: Anthozoa) reef in Greenlandic waters

“…This system is capable to 4000 m depth, and houses a Canon Rebel Eos Ti 12 megapixel camera and two Canon flashes enclosed inside an aluminum roll cage. The area covered by the field of view of each photograph when the camera is landed squarely on the sea floor is 0.47 ± 0.05 m 2 (mean ± SD) (Beazley et al 2013). Temperature and depth were measured with a Sea-Bird Electronics SBE 39 recorder attached to the 4KCam.…”