Early Life History of Deep-Water Gorgonian Corals May Limit Their Abundance

Abstract

Deep-water gorgonian corals are long-lived organisms found worldwide off continental margins and seamounts, usually occurring at depths of ∼200–1,000 m. Most corals undergo sexual reproduction by releasing a planktonic larval stage that disperses; however, recruitment rates and the environmental and biological factors influencing recruitment in deep-sea species are poorly known. Here, we present results from a 4-year field experiment conducted in the Gulf of Maine (northwest Atlantic) at depths >650 m that document recruitment for 2 species of deep-water gorgonian corals, Primnoa resedaeformis and Paragorgia arborea. The abundance of P. resedaeformis recruits was high, and influenced by the structural complexity of the recipient habitat, but very few recruits of P. arborea were found. We suggest that divergent reproductive modes (P. resedaeformis as a broadcast spawner and P. arborea as a brooder) may explain this pattern. Despite the high recruitment of P. resedaeformis, severe mortality early on in the benthic stage of this species may limit the abundance of adult colonies. Most recruits of this species (∼80%) were at the primary polyp stage, and less than 1% of recruits were at stage of 4 polyps or more. We propose that biological disturbance, possibly by the presence of suspension-feeding brittle stars, and limited food supply in the deep sea may cause this mortality. Our findings reinforce the vulnerability of these corals to anthropogenic disturbances, such as trawling with mobile gear, and the importance of incorporating knowledge on processes during the early life history stages in conservation decisions.

A Five-Year, In Situ Growth Study on Shallow-Water Populations of the Gorgonian Octocoral Calcigorgia spiculifera in the Gulf of Alaska

“…The presence of large, heavily yolk-laden embryos and planula larvae in the female polyps indicates a late summer or early fall recruitment. So the factors that are limiting recruitment at our study sites do not appear to be inadequate spawning biomass or the lack of adequate recruitment habitat but some other factor, possibly early settlement predation [41]. …”

Large-Scale Genotyping-by-Sequencing Indicates High Levels of Gene Flow in the Deep-Sea Octocoral Swiftia simplex (Nutting 1909) on the West Coast of the United States

“…simplex , can impact their ability to recover from anthropogenic disturbances, including fisheries activities, and thus have implications for their protection and management [11, 12, 25, 27, 55]. Deep-sea corals are a critical component of the deep-sea ecosystem, creating structural habitats that support a diversity of additional species, including commercially important fisheries.…”

“…Corals exhibit a diversity of life history traits including reproductive modes (see [14] for a review of reproduction in octocorals), and population structures. In some coral species, patterns of spatial population structure follow expectations of life history traits: individuals that are broadcast spawners disperse further, resulting in higher gene flow between populations, which reduces population differentiation [11, 13]. In contrast, species that brood their larvae can have more limited recruitment distances, resulting in lower levels of gene flow and subsequently higher levels of genetic structure [11, 13, 15].…”

“…In some coral species, patterns of spatial population structure follow expectations of life history traits: individuals that are broadcast spawners disperse further, resulting in higher gene flow between populations, which reduces population differentiation [11, 13]. In contrast, species that brood their larvae can have more limited recruitment distances, resulting in lower levels of gene flow and subsequently higher levels of genetic structure [11, 13, 15]. However, there are exceptions to this pattern and dispersal of larvae can be influenced by both biological and physical factors including larval behavior, larval duration, mortality, reproductive timing, oceanographic circulation patterns, and availability of suitable settlement habitat [11, 16, 17].…”

Environmental Impacts of the Deep-Water Oil and Gas Industry: A Review to Guide Management Strategies

“…Cold-seep tubeworms and deep-water corals exhibit slow growth and some of the greatest longevities among marine metazoans, typically decades to hundreds of years, but occasionally to thousands of years (Fisher et al, 1997;Bergquist et al, 2000;Andrews et al, 2002;Roark et al, 2006;Cordes et al, 2007;Watling et al, 2011). Recruitment and colonization dynamics are not well-understood for these assemblages, but recruitment appears to be slow and episodic in cold-seep tubeworms , mussels (Arellano and Young, 2009), and deep-sea corals (Thresher et al, 2011;Lacharité and Metaxas, 2013;Doughty et al, 2014).…”