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Fast-growing and reproducing sun corals have successfully invaded rocky reefs around the Atlantic Ocean, markedly reducing the diversity of fouling invertebrates and macroalgae, and profoundly changing the composition of reef-associated mobile invertebrates. Here, we address sun-coral rubble depositions and report, for the first time, the effects of sun corals on near-reef soft-bottom invertebrate assemblages. Abundance, richness and diversity were higher at rubble habitats compared to bare sandy grounds, which could be a positive effect of substrate complexity. All those parameters were also higher at rubble patches dominated by sun-coral fragments compared to rubble patches dominated by pebbles or shell fragments, also suggesting possible additive effects of coral-borne chemical attraction (sun-coral specific, as inputs of other coral species were virtually absent). Different epifaunal groups were exclusive of rubble habitats and a subset of those exclusive of sun-coral rubble, explaining the incremental richness across habitats. The relative abundance of the two dominant groups – polychaetes (p) and amphipods (a) – contributed the most to the observed contrasts on community structure, as their proportion (p:a) changed from 10:1 in bare sand to nearly co-dominance in coral rubble. While previous research suggested that spreading sun corals reduce prey supply for fish foraging on reef walls, our results suggest they may increase prey abundance and diversity at the adjacent non-consolidated habitat, possibly reshaping trophic pathways connecting the benthic and the pelagic environment. [Display omitted] • Invasive sun corals in southeastern Brazil generate near-reef rubble accumulations. • Mobile invertebrates are abundant in common rubble and sun coral rubble. • Invertebrate richness and diversity are lowest in sand and highest in coral rubble. • Complexity and chemical cues may explain variation of invertebrates across substrata. • Sun-coral rubble may alter reef trophic networks. [ABSTRACT FROM AUTHOR]

The susceptibility of a community to invasions is not the only factor influencing the success of the introduction of non-indigenous species (NIS). Because the conditions of the invaded environment tend to be unpredictable, plastic responses should increase the success of NIS in a new environment. Sun-corals are invaders in the Atlantic Ocean that present a range of strategies and plastic responses to deal with stress and distinct environmental conditions. We experimentally tested the plastic responses of sun-corals when exposed to different predation pressures and hydrodynamics in a recreational marina where sun-corals abundance varies spatially along with the environmental conditions. We separated young sun-coral colonies in two experiments: one controlling the presence of predators and the other manipulating water motion. While predation had no effect, revealing that even small young colonies are somehow protected against predators, corals increased colony area under reduced water motion but grew more polyps under greater water motion. These results highlight that plasticity in modular growth may be important for sun-corals to successfully invade distinct regions despite the hydrodynamic conditions. Increasing the colony area implicate in monopolization of space in calmer waters whilst growing more polyps allows it to have more mouths for feeding in turbulent food-poor waters. This response is particularly interesting as it is similar to the response of another NIS in the same site—the bryozoan Schizoporella errata. Phenotypic plasticity of reproductive strategies, including asexual propagation as observed here, appears to be relevant for modular NIS by facilitating the success on the invasion process in variable habitats. • Predation did not affect sun-corals growth in our study. • Colonies growing in calmer food-rich waters invested more in area growth. • Colonies growing in more hydrodynamic food-poor waters invested more in new polyps. • This plastic growth is convergent to another non-indigenous bryozoan in the area. • The plastic response to hydrodynamics may add to the invasion success of sun-corals. [ABSTRACT FROM AUTHOR]

Deep-sea coral communities are poorly known in the Southwestern Atlantic (SWA), particularly in the equatorial/subequatorial latitudes embraced by the northeastern Brazilian Exclusive Economic Zone (EEZ). Such knowledge gap has lead to the idea that the latter has low species richness when compared to southern Brazilian regions. Recent studies, however, indicate the northeastern slope as highly suitable for deep-sea coral habitats. Herein, based on recent sampling efforts, we confirm that deep-sea coral richness in that region is higher than previously thought. Trawl surveys carried out in 2011 at the Potiguar Basin, Rio Grande do Norte State, yielded the identification of at least 51 coral species, including 28 octocorals, 16 scleractinians, and seven antipatharians, including five new records for the South Atlantic and 11 new occurrences for the northeastern Brazilian waters. Comprising 29 species, the upper slope communities (102–200 m) showed the highest richness. Species richness between northeastern and southern Brazil is briefly compared, indicating a decrease of species richness southwards. Since most of the studied area is under influence of the same water masses, proximity to the Caribbean fauna may explain the species richness found in the northern Brazilian external shelf and slope. Finally, we suggest that biogeographic units within the Brazilian upper and middle slope are closer to shallow-water provinces than to deep-sea ones. • Models suggest a high richness of octocorals in the Northeastern Brazilian margin. • Trawl surveys yielded 51 deep-sea coral species from that area, 28 are octocorals. • Upper slope communities (102–200 m) showed the highest species richness. • Proximity whit the Caribbean may explain the species composition in NE Brazil. • Biogeographic delimitations place upper and middle slope closer to shallow-water provinces. [ABSTRACT FROM AUTHOR]

Scleractinian cold-water corals are found across the Northeast Atlantic, providing structure for important habitats that support high biodiversity. Climate-driven perturbations on parameters such as carbonate chemistry, oxygen, bottom currents, productivity and temperature have the potential to impact the abundance and diversity of these cold-water coral communities. One way to explore the linkage between corals and climate is to examine historic coral distributions during times of past climate change. Previous coral dating efforts in the Northeast Atlantic (n ∼ 700) have focused on reef-forming colonial coral communities from shelf and slope areas. However, there are far fewer data from open-ocean settings or from solitary coral species, thus precluding assessment of basin-wide controls on coral occurrence. Here, we contribute >600 new U-series ages for both solitary and colonial coral species from open-ocean sites including the Reykjanes Ridge and seamounts in the mid and low latitudes to map the changing distribution of Northeast Atlantic cold-water corals over the last 150,000 years. The temporal occurrences of solitary and colonial corals from our offshore sites are broadly similar to the distributions along the nearer-shore sites at the same latitudes. In the cold-temperate and high-latitude Northeast Atlantic, corals are most abundant during warm climate intervals, with the Reykjanes Ridge (60°N) representing the northernmost limit of corals in the Northeast Atlantic during Marine Isotope Stage (MIS) 5, MIS 3 and Bølling-Allerød. This biogeographical distribution expanded northwards to the Norwegian margin at the onset of the Holocene when the ice sheets retreated and modern-like oceanographic conditions were established. We interpret the abundance of corals at these northerly sites to be linked with increased food supply and favourable hydrological conditions. By contrast, coral sites south of 45°N are characterised by glacial and deglacial occurrences, with a marked decline during the Holocene. This distribution is also linked to food supply, potentially driven by shifts in dust fertilization and upwelling, in addition to changes in dissolved oxygen concentration and temperature. Together, these findings emphasize the links between climate, oceanic processes, and cold-water coral distribution, pointing to low food supply and low oxygen concentration as limiting factors for cold-water coral populations. Both parameters are changing in the modern ocean, with implications for future coral communities. [Display omitted] • 616 new U–Th ages double the number of radiometrically dated corals in NE Atlantic. • Similar temporal occurrence of open-ocean, shelf and slope cold-water coral sites. • Corals are abundant during warm climate intervals at sites north of 40°N. • Coral abundance peaked at last glacial-deglacial interval at tropical sites. • Coral habitat dictated by productivity, dissolved oxygen, and ocean circulation. [ABSTRACT FROM AUTHOR]