Environmental matching used to predict range expansion of two invasive corals (Tubastraea spp.)

A tool for a race against time: Dispersal simulations to support ongoing monitoring program of the invasive coral Tubastraea coccinea

Preventing, detecting, and monitoring invasive marine species is a big challenge as it is not possible to visualize all invasion extensions. Their early detection may be the best chance to achieve eradication. The Indo-pacific scleractinian coral Tubastraea coccinea invasion in the Atlantic dates from the late 1930s. Since then, disruptive populations were found along ~8.000 km of west Atlantic, and in the Canarian Islands of Spain (east Atlantic), related to vessel fouling in the oil and gas industry. Their impacts have been noticed from endemic species to ecosystems. In Brazil, initiatives to control Tubastraea spp. have been done mostly by local environmental managers and researchers, but recently a National Plan for Prevention, Control and Monitoring (NPPCM) for Tubastraea spp. was approved. We applied an Individual-based Model within the invasion history of Tubastraea coccinea in its southern distribution limit in the Atlantic, on the rocky shore of the Arvoredo Biological Marine Reserve. We indicated hotspots for the occurrence of possible emerging invasion sites in the region and expect to support ongoing monitoring programs in defining priority areas for their early detection. The model is easily replicated and might be a valuable tool for decision makers.

Importance of Anthropogenic Determinants of Tubastraea coccinea Invasion in the Northern Gulf of Mexico

Tubastraea coccinea is an invasive coral that has had ecological, economic, and social impacts in the Atlantic Ocean, the Caribbean Sea, and the Gulf of Mexico (GoM). Tubastraea coccinea is considered a major threat to marine biodiversity, whose occurrence in its non-native range has been associated with artificial structures such as oil/gas platforms and shipwrecks. A recent species distribution model identified important determinants of T. coccinea invasion in the northern GoM and projected its potential range expansion. However, the potential effects of anthropogenic factors were not considered. We used boosted regression trees to develop a species distribution model investigating the importance of oil/gas platforms and shipping fairways as determinants of T. coccinea invasion in the northern GoM. Our results indicate that maximum salinity, distance to platform, minimum nitrate, and mean pH were the first to fourth most influential variables, contributing 31.9%, 23.5%, 22.8%, and 21.8%, respectively, to the model. These findings highlight the importance of considering the effects of anthropogenic factors such as oil/gas platforms as potential determinants of range expansion by invasive corals. Such consideration is imperative when installing new platforms and when decommissioning retired platforms.

Living with an enemy: Invasive sun-coral (Tubastraea spp.) competing against sponges Desmapsamma anchorata in southeastern Brazil

The azooxanthellate corals Tubastraea coccinea and T. tagusensis invaded the Brazilian coast in the 1980s and is still in expansion, favored by lower predation and competition pressure in their new habitats. Interestingly, the native sponge Desmapsamma anchorata has been observed overgrowing these corals. Considering that competitive displacement is expected to play a major role in the successful outcome of an invasion, the present study tested the physical and chemical mechanisms possibly involved in the competition between D. anchorata and the Tubastraea corals through field and aquaria experiments as well as the Raman spectroscopy technique for chemical analysis. Our results showed that the sponge grew in all directions including over Tubastraea colonies and regardless of its presence. There was no evidence of a specific chemical response among sponges or corals. However, we observed the extrusion of mesenteric filaments and tentacles of corals and the projection of sponge tissue during interspecific interaction, which suggests that physical imposition plays a key role for space competition at micro scales. Given the interspersed nature of benthic species distributions and the fast expansion of Tubastraea, it is unlikely that D. anchorata or any other sponges could serve a biological control against these invasive corals at larger scales, but our results showed that at a microscale they can withstand the corals presence and even outgrow them locally.

Contrasting coral community structures between natural and artificial substrates at Koh Tao, Gulf of Thailand

Concrete cubic frames and decommissioned steel naval vessels have been deployed in Thailand liberally to act as artificial substrates for coral restoration and marine recreation. We assessed recruitment at such substrate types at Koh Tao, Gulf of Thailand, and compared the community structure of scleractinian corals between artificial substrates and nearby natural reefs. Our results from a sample of 2677 recruits from nine sites highlighted significant differences in community structure between both reef types. Investigations of variables including time since deployment, distance from the natural reef, and seafloor depth revealed only the latter as a possible influencing factor. The diversity of recruits could not be explained by dynamics in coral spawning, and were found to represent groups with lower structural complexity. Our results suggest that coral community structure on artificial and natural reefs differs and supports distinct ecological and functional roles.

A Method to Assess the Risk of Sun Coral Invasion in Marine Protected Areas

The safest and most efficient method of avoiding costs and impacts associated with biological invasions is to prevent the introduction and establishment of non-native species. In Brazil, two invasive coral species have been causing ecological, economic and social impacts: Tubastraea coccinea and Tubastraea tagusensis. This work presents a protocol to analyze the risk of invasion in Marine Protected Areas (MPAs) in the State of Rio de Janeiro considering the main vector of these species on the Brazilian coast. This protocol takes five risk factors into account: environmental similarity between the donor area and the possible receiving area; available substrate for colonization; proximity to the donor region; proximity and quantity of oil platforms and drill ships that passed by the analyzed MPAs and proximity and quantity of oil platforms and drill ships that anchored near the MPAs. Results must be used by decision-makers for a better management of Marine Protected Areas. The protocol we present can be applied to analyze the relative risk of invasion throughout the Brazilian coast, in order to prioritize areas for early detection and monitoring of the presence of sun corals.

How Do Biological and Functional Diversity Change in Invaded Tropical Marine Rocky Reef Communities?

Evidence so far shows that most alien species (AS) have negative impacts on native biodiversity and are changing biodiversity in almost all environments. Here, we study eight rocky shores at four sites containing reefs with invaded communities and other not-invaded (control) communities, to evaluate the effects of four marine invasive species on biological and functional diversity. We used the adjustment and selection approach of species abundance distribution models (SAD), taxonomic diversity indices and functional diversity indices based on hierarchical grouping matrices (FD—Functional Diversity). In addition to comparing invaded and not-invaded communities, we also performed the same analysis, but removed the invaders (AS removed) from the matrices. The geometric-series model was best adjusted to the majority of communities. The diversity indices suggest that the taxonomic diversity is lower in invaded communities, while the functional diversity indices suggest a change in the functional space of invaded and not-invaded communities, with a greater amount of functional space filled by species in the not-invaded communities. Taxonomic and functional diversity indices were successful in identifying processes that determine the biological diversity of invaded communities, as they seem to obey a pattern that reflects the reduced diversity of invaded communities.

Shipwrecks help invasive coral to expand range in the Atlantic Ocean

The invasive coral Tubastraea tagusensis (sun coral) is a habitat-forming species currently increasing its geographical range into the Atlantic Ocean, thereby causing negative ecological and socioeconomic impacts. Scuba divers observed this coral in the western equatorial Atlantic in January 2020, growing at high densities on a shipwreck from World War II (sunk in 1943) at a depth of approximately 32 m. Available footage from the beginning of the decade (2012-2018) shows no obvious signs of sun coral on this shipwreck, suggesting recent colonization and range expansion. The recent evidence of expansion was found 200 km east of the last record, which was also found on a WWII shipwreck (sunk in 1942) in 2016. We have identified hundreds of overlooked WWII shipwrecks, as well as new wrecks in shallow and mesophotic waters, that may provide stepping-stone habitats for this coral to expand its distribution in the Atlantic. We discuss the role of shipwrecks as a network of stepping stones for the sun coral spread, creating complementary paths for the invasiveness by overcoming physiological traits and the short lifespan of the coral larvae. Previous research underestimates the importance of these artificial stepping-stone patches in sustaining crucial dispersal events and range expansion of invasive species. These results are a call to action to manage the invasive Tubastraea corals at a national and international scale in the Atlantic basin.