Population expansion of a new invasive coral species, Tubastraea micranthus, in the northern Gulf of Mexico

Abstract

An Indo-Pacific scleractinian coral has invaded the northern Gulf of Mexico (GOM): Tubastraea micranthus. It was initially observed on one oil platform (GI-93C) near the Mississippi River. Here, we determined whether its populations were spreading and whether there was evidence of rapid expansion. We compared population density data of T. micranthus with those from T. coccinea, a congener which invaded the western Atlantic earlier. Fourteen oil/gas platforms were assessed down to 138 m depth using remotely operated vehicle digital video. Colony densities in numbers m −2 were determined for both species, and colony size was measured for T. micranthus. Data were analyzed by platform and for geographic distribution. T. micranthus densities were highest on GI-93C and on GI-116A, SW of the Mississippi River, being significantly higher than on other platforms. Densities declined radially from there. Mean colony size was highest on MC-311A, with colonies generally being >100 cm 2 . This platform is situated at the head of the Mississippi Canyon and may have been the original site of colonization. It also receives blue water instead of turbid, lower salinity water, and this species may grow better under those conditions. T. micranthus size frequency distributions were generally skewed towards 1-200 cm 2 (5 cm diameter) (sometimes > 90% of the population), suggesting that most populations are potentially in an expanding growth phase. T. coccinea densities were high (range: ~50 to 300 colonies m −2 ). Its populations were also centered SW of the Mississippi River. T. micranthus is spreading through this region, and the window for its potential eradication may be closing.

Assessment of Mesophotic Coral Ecosystem Connectivity for Proposed Expansion of a Marine Sanctuary in the Northwest Gulf of Mexico: Population Genetics

“…Naturally, this does not preclude the potential for occasional export of larvae beyond the NW GOM and successful gene flow to other reefs hundreds of kilometers away, as has been suggested by biophysical and genetic data (Davies et al, 2017;Rippe et al, 2017;Garavelli et al, 2018). Stepping-stone dynamics among other reef habitats in the NW GOM including scleractinian communities on oil and gas platforms (Sammarco et al, 2004(Sammarco et al, , 2012(Sammarco et al, , 2013(Sammarco et al, , 2014 and mesophotic banks in the eastern GOM (Hine et al, 2008;Locker et al, 2010;Silva and MacDonald, 2017) may also influence coral population connectivity in the region.…”

Success in Competition for Space in Two Invasive Coral Species in the western Atlantic – Tubastraea micranthus and T. coccinea

“…A total of fifteen platforms within a 25 km radius south of the mouth of the Mississippi River were initially surveyed ( Fig 1 ; Table 1 ; [ 8 ]. Nine platforms possessed Tubastraea micranthus in sufficient numbers to be statistically analysed for frequency of competitive success.…”

“…Over the past 70 yrs, there have been several invasions of coral species to the western Atlantic. One was that of Fungia scutaria [ 6 , 7 , 8 ], which was introduced to northern Jamaican waters in Discovery Bay in the 1960s/1970s. Fungia is a vagile Indo-Pacific fungiid coral and lives primarily on soft-bottom [ 9 ].…”

“…We recently reported that Tubastraea micranthus invaded an area south of the Mississippi River mouth [ 21 ], having colonized offshore oil and gas platforms in this area. Later, we found that their populations were spreading rapidly throughout this region [ 8 ]. They have been found to extend to depths below the depth-distribution of the co-occurring congener T .…”

Anthropogenic disturbance facilitates a non‐native species on offshore oil platforms

“…Non-native species often thrive on artificial structures in the marine environment (Mineur et al, 2012). Offshore energy infrastructure, such as oil or natural gas platforms and renewable energy installations, introduce hard substrate into an offshore environment typically characterized by soft sediments, and consequently provide novel habitat for reef-associated species (De Mesel, Kerckhof, Norro, Rumes, & Degraer, 2015;Page, Dugan, Culver, & Hoesterey, 2006;Sammarco, Porter, Sinclair, & Genazzio, 2014). These artificial islands may serve as "stepping stones" of habitat that increase regional connectivity via planktonic larval dispersal, thereby facilitating species range expansions (Adams, Miller, Aleynik, & Burrows, 2014;Sheehy & Vik, 2009;Simons et al, 2016).…”