Embryo and larval biology of the deepsea octocoral Dentomuricea aff. meteor under different temperature regimes

Deep-sea octocorals are common habitat-formers in deep-sea ecosystems, however, our knowledge on their early life history stages is extremely limited. The present study focuses on the early life history of the species Dentomuricea aff. meteor, a common deep-sea octocoral in the Azores. The objective was to describe the embryo and larval biology of the target species under two temperature regimes, corresponding to the minimum and maximum temperatures in its natural environment during the spawning season. At temperature of 13 ±0.5 °C, embryos of the species reached the planula stage after 96h and displayed a median survival of 11 days. Planulae displayed swimming only after stimulation, swimming speed was 0.24 ±0.16 mm s−1 and increased slightly but significantly with time. Under a higher temperature (15 °C ±0.5 °C) embryos reached the planula stage 24 h earlier (after 72 h), displayed a median survival of 16 days and had significantly higher swimming speed (0.3 ±0.27 mm s−1). Although the differences in survival were not statistically significant, our results highlight how small changes in temperature can affect embryo and larval characteristics with potential cascading effects in larval dispersal and success. In both temperatures, settlement rates were low and metamorphosis occurred even without settlement. Such information is rarely available for deep-sea corals, although essential to achieve a better understanding of dispersal, connectivity and biogeographical patterns of benthic species.Versión del edito

A road map for defining Good Environmental Status in the deep-sea

The development of tools to assess the Good Environmental Status (GES) in the Deep Sea (DS) is one of the aspects that ATLAS WP3 is addressing. GES assessment in the DS is challenging due to 1) the lack of baseline data, 2) the remoteness of the DS ecosystems, and 3) the limitations of the sampling methods currently available. Throughout the duration of the project, ATLAS will develop a suitable approach to address GES in the DS. During the 2nd General Assembly, we will present a draft for a “road map” to address GES in the DS as well some of the aspects discussed during the 2017 ICES WG on Deep Sea Ecosystems. The temporal and spatial scale at which GES should be assessed in the deep-sea is an important aspect to be considered. Due to the data limited situation and challenges posed to monitoring, it may well be the case that GES will have to be assessed at large spatial and temporal scales when comparing the shallower waters of the European Seas. For similar reasons, the type of indicators to be used may have to be simplified and likely be based on high-level analyses related to traits, pressures/risks, and habitat /ecosystem resilience. Ultimately, the results of the combined analyses of GES descriptors might bring to a potential refining or redefinition of the GES concept for the deep-sea

Living in close quarters: Epibionts on Dendrophyllia ramea deep-water corals (Cyprus and Menorca Channel)

In sharp contrast to shallow and/or tropical coral habitats, the role of deep-water corals (DWC) as habitat providers is not well known and even less understood. For this purpose, epibionts on the deep-water coral Dendrophyllia ramea were studied from samples collected in Cyprus and compared to those from Menorca Channel. A total of 63 species were found; bryozoans (ca. 60%) and serpulid polychaetes (ca. 10%) dominated the assemblage of species. Cyprus (48 species in total) and Menorca (22) corals shared few epizoic species (7). Several of these species were previously thought absent from the Levantine basin. These results are important contributions to the knowledge on the deep-water epibiotic biodiversity of the Levantine Basin and the Mediterranean Sea in genera

Reproduction in the externally brooding sea anemone Epiactis georgiana in the Antarctic Peninsula and the Weddell Sea

14 pages, 8 figures, 2 tablesExternal parental care is uncommon among actiniarians but common in Epiactis species. Here, several aspects of reproduction are analyzed for of one of them, Epiactis georgiana. Samples were collected in December, January, February, March, and April in the Antarctic Peninsula and the eastern Weddell Sea, during 1998, 2000, 2002, and 2003. Most sexually mature individuals of E. georgiana are male or female, but some are hermaphrodites. This is the first report of hermaphroditism in E. georgiana, which is the third species of the genus with this sexual pattern. The results suggest that oogenesis starts in December and that at least two generations of oocytes overlap; a third generation is often brooded externally. Putative fertilization is likely internal, and larvae and/or embryos are externally brooded on the distal part of the adult column until an advanced developmental stage. Apparently E. georgiana reproduces seasonally, probably releasing the embryos/larvae in the last months of the austral spring (December). Inter-individual variability was observed in gametogenesis. In addition, specimens from the Antarctic Peninsula were larger than those from the Weddell Sea. This study represents the first step in understanding the reproductive mode of E. georgianaSpecial thanks are addressed to Prof. Dr. Wolf Arntz (Alfred-Wegener-Institute, Bremerhaven, Germany) who made possible our participation in several Antarctic projects and cruises. We extend our acknowledgements to the officers and crew of the R/V Polarstern and many colleagues on board during the EASIZ, ANDEEP, and BENDEX cruises for their valuable assistance. Thanks to M. Conradi (Universidad de Sevilla) who collected a considerable amount of the material analyzed in this manuscript. Comments from M. Daly, D. Fautin, and an anonymous reviewer substantially improved this manuscript. Support was provided by a MCT-CSICgrant (I3P-BPD2001-1) to E. Rodríguez and Spanish CICYT projects: ANT97-1533-E, ANT98-1739-E, ANT99-1608-E, REN2001-4269-E/ANT, REN2003-04236, and CGL2004-20141-E. This is a contribution to the SCAR program, Ecology of the Antarctic Sea Ice Zone (EASIZ) and ANDEEP contribution 159Peer reviewe