New non-native ornamental octocorals threatening a South-west Atlantic reef

Abstract

Invasive species are leading to ecosystem changes and socioeconomic deterioration around the globe. In 2018, unknown soft corals were noticed forming a massive ‘blue carpet’ on a shallow reef environment at Todos os Santos Bay, South-west Atlantic. In this study we identified the species, quantified their distribution and abundance as a first step for baseline invasion monitoring, and discussed origin, vector and impacts on native competitors. Coral samples were identified based on morphology and a multilocus DNA barcode, and benthic structure was characterized using digital photoquadrats. Our results revealed two new harmful non-native octocorals in this tropical rocky reef, the ‘blue polyps’ genus Sarcothelia (Xeniidae), native to Hawaii but likely an undescribed cryptic species, and Briareum hamrum (Briareidae), native to the Indian Ocean. Sarcothelia sp. was the dominant taxon in the rocky reef (mean cover 23.66% ± 21.46), exhibiting high coverage as well in the sandy and patch reef habitats (15.83% ± 15.81), however, only three colonies of B. hamrum were found, all outside the sampling area. These octocorals were in physical contact with native benthic organisms, mainly with the most abundant group, but apparently avoid turf algae in sandy and patch reef habitats. We suggest that irresponsible marine aquarium releases likely introduced these species to Brazilian reefs. After identifying the aquarium trade as the main vector of octocoral introductions, we reinforce the importance of inspecting marine species importation and the urgent need to implement a government plan to mitigate invasive species' impacts on the natural reefs of Brazil.

Neospongodes atlantica, a potential case of an early biological introduction in the Southwestern Atlantic

“…For example, an invasive xeniid octocoral has invaded the Venezuelan Caribbean and, more recently, its abundance has surpassed that of all other benthic taxa in that region ( Ruiz-Allais, Benayahu & Lasso-Alcalá, 2021 ). Invasive xeniids and other non-indigenous octocoral species from other families have also been reported in Brazil ( Mantelatto et al, 2018 ; Carpinelli et al, 2020 ; Menezes et al, 2021 ), raising concerns on the fate of invaded localities biodiversity and, consequently, ecosystem function. Therefore, we recommend that populations of N. atlantica should be monitored in order to keep track of its spread and eventual invasiveness in Brazilian marine environments, along with other recently aquarium-introduced octocorals ( Mantelatto et al, 2018 ; Carpinelli et al, 2020 ).…”

A new blue astrangiid coral from the Southwestern Atlantic: coral diversity under globalization

“…A fourth species, A. poculata (Ellis & Solander, 1786), also occurs in the Western Atlantic, but it has not been reported to Brazil yet (Peters 1988;Cairns 2000). Astrangia poculata has a reduced number of septa (30)(31)(32)(33)(34)(35)(36), but the calice diameter of the corallites may vary enormously, from the smallest size among the congeners (1.0 mm), it may be bigger than in A. rathbuni (7.0 mm). In addition, the corallites of A. poculata are closer, with a poorly developed coenosteum, sometimes completely absent.…”

“…It is noteworthy that two exotic octocorals from the Indo-Paci c have been recently identi ed in the TSB: the blue Sarcothelia sp. Verrill, 1928 and Briareum hamrum (Gohar, 1948) -capable to form extensive mats they are rapidly spreading on natural substrates (Menezes et al 2022).…”

Effect of the alien octocoral Carijoa riisei on benthic fauna assemblages on natural and artificial substrates

“…Other soft coral species were introduced in the Atlantic such as Chromonephthea braziliensis van Ofwegen, 2005 (identified before as Stereonephthya aff. curvata ) (Ferreira, 2003), Erythropodium caribaeorum (Duchassaing & Michelotti, 1860) (Carpinelli et al, 2020), Briareum hamrum (Gohar, 1948) (Menezes et al, 2021), Sansibia sp. and Clavularia cf.…”