The relationship between fish abundance and benthic community structure on artificial reefs in the Mid-Atlantic Bight, and the importance of sea whip corals Leptogorgia virgulata

Abstract

Autogenic engineers (i.e., biogenic structure) add to habitat complexity by altering the environment by their own physical structures. The presence of autogenic engineers is correlated with increases in species abundance and biodiversity. Biogenic structural communities off the coast of Delaware, Maryland, and Virginia (Delmarva) are comprised of multiple species including boring sponge Cliona celata, various hydroids (i.e., Tubularia sp., Obelia sp., Campanular sp.), northern stone coral Astrangia poculata, sea whips Leptogorgia virgulata, and blue mussels Mytilus edulis. Sea whips are soft corals that provide the majority of vertical height to benthic structure off the coast of the Delmarva peninsula. The mid-Atlantic bight is inhabited by several economically valuable fishes; however, data regarding habitat composition, habitat quality, and fish abundance are scarce. We collected quadrat and sea whip images from 12 artificial reef sites (i.e., shipwrecks) ranging from 10 to 24 m depth to determine proportional coverage of biogenic structures and to assess habitat health, respectively. Underwater video surveys were used to estimate fish abundances on the 12 study sites and determine if fish abundance was related to biogenic coverage and habitat health. Our results showed that higher fish abundance was significantly correlated with higher proportional sea whip coral coverage, but showed no significant relationship to other biogenic structure. Assessment of sea whip condition (as a damage index) showed that sea whip corals on artificial reefs off the Delmarva coast exhibited minor signs of degradation that did not differ significantly among study sites.

Sea whip coral Leptogorgia virgulata in the Mid-Atlantic Bight: Colony complexity, age, and growth

“…in the South Atlantic Bight (Van Dolah, Wendt & Nicholson, 1987;Steimle & Figley, 1996;Able & Fahay, 1998;Cullen & Stevens, 2017). Additionally, Schweitzer & Stevens (2019) found fish abundance to positively correlate with sea whip coverage on artificial Delmarva reef habitats, and that sea whips were the only biogenic structure in the study significantly related to fish abundance.…”

“…In the Delaware, Maryland, and Virginia (Delmarva) region of the MAB the sea whip Leptogorgia virgulata is a common component of natural and artificial hard-bottom reefs (Steimle & Zetlin, 2000;Cullen & Stevens, 2017;Schweitzer, Lipcius & Stevens, 2018;Schweitzer & Stevens, 2019). These corals can be found along the North American Atlantic coast, and have been observed at depths of 2-59 m (Bayer, 1961;Gotelli, 1988;Devictor & Morton, 2010;Packer et al, 2017).…”

“…Sea whips in the Delmarva region show evidence of damage and overgrowth by fouling organisms (R Wenker andB Stevens, pers. obs., 2017 and2018;Schweitzer, Lipcius & Stevens, 2018;Schweitzer & Stevens, 2019). This includes overgrowth by organisms such as mussels, bryozoans, ascidians, and sponges, as well as damaged and stripped tissue.…”

Peer Review #1 of "Sea whip coral Leptogorgia virgulata in the Mid-Atlantic Bight: Colony complexity, age, and growth (v0.1)"

“…in the South Atlantic Bight (Van Dolah, Wendt, and Nicholson 1987;Steimle and Figley 1996;Able and Fahay 1998;Cullen and Stevens 2017). Additionally, Schweitzer and Stevens (2019) found fish abundance to positively correlate with sea whip coverage on artificial Delmarva reef habitats, and that sea whips were the only biogenic structure in the study significantly related to fish abundance.…”

“…In the Delaware, Maryland, and Virginia (Delmarva) region of the MAB the sea whip Leptogorgia virgulata is a common component of natural and artificial hard-bottom reefs (Steimle and Zetlin 2000;Cullen and Stevens 2017;Schweitzer et al 2018;Schweitzer and Stevens 2019). These corals can be found along the North American Atlantic coast, and have been observed at depths of 2-59 meters (Bayer 1961;Gotelli 1988;DeVictor and Morton 2010;Packer et al 2017).…”