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

Les comunitats de coralls al canó de cap de Creus

En la darrera dècada, les comunitats de coralls blancs han despertat l’interès dels científics a nivell mundial a causa, en part a la seva rellevància ecològica i en part a la seva desconeixença. Els escrits antics, des d’inicis del segle XX se sap que aquestes comunitats eren molt abundants en el límit de la plataforma continental a la Mediterrània entre 150 i 400 m de fondària. Actualment estan confinats a indrets on les activitats pesqueres de ròssec no les hagin malmès i és urgent trobar i avaluar el seu estat per promoure la seva conservació.Un dels indretsmés on es pot confirmar la presència i bon estat de conservació en la Mediterrània és el canó submarí de cap de Creus. Sobretot a la paret del sud del canó s’han pogut estudiar poblacions molt importants del corall Madrepora oculata i algunes petites poblacions de Lophelia pertusa. Les colònies d’aquests coralls configuren un hàbitat singular i de gran diversitat resultat, en part, de l’elevada producció biològica de l’àrea del cap de Creus i també perquè la seva localització a la paret del canó ha dificultat la destrucció encara que avui en dia les línies de palangre són l’amenaça més directa per a la seva supervivència.In the last decade, colonies of white coral have become of interest to scientists worldwide, partly because of their ecological relevance and partly because they are still little known. From older writings from the beginning of the twentieth century we know that these colonies were very frequent on themargins of the continental shelf in the Mediterranean between 150 and 400m deep. Nowadays, they are confined to areas where trawling activities have not destroyed them and it is urgent to find and evaluate its current state in order to promote its conservation. Another Mediterranean area where it can be found, and well-conserved, is the submarine channel of the Cap de Creus. Especially on the south side of the channel, important colonies of the Madrepora oculata coral have been studied and some smaller ones of Lophelia pertusa. These coral colonies make up a unique habitat of great diversity as a result of, in part, the elevated biological production of the Cap de Creus area. And also because their situation on the channel’s wall has protected them from destruction, although longline fishing represents a direct threat against its survival still today

Uptake of dissolved free amino acids by four cold-water coral species from the Mediterranean Sea

Dissolved organic matter, which contains many compounds such as lipids, sugars and amino acids, is an important source of carbon and nitrogen for several symbiotic and asymbiotic tropical coral species. However, there is still no information on its possible uptake by cold-water coral species. In this study, we demonstrated that dissolved organic matter, in the form of dissolved free amino acids (DFAA), is actively absorbed by four cold-water coral species from the Mediterranean Sea. Although the uptake rates observed with 3mM DFAA concentration were one order of magnitude lower than those observed in tropical species, they corresponded to 12–50% of the daily excreted-nitrogen, and 16–89% of the daily respired-carbon of the cold-water corals. Consequently, DFAA, even at in situ concentrations lower than those tested in this study, can supply a significant amount of carbon and nitrogen to the corals, especially during periods when particulate food is scarce. Versión del editor

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

Cold-water coral reefs thriving under hypoxia

Reefs formed by scleractinian cold-water corals represent unique biodiversity hot spots in the deep sea, preferring aphotic water depths of 200–1000 m. The distribution of the most prominent reef-building species Lophelia pertusa is controlled by various environmental factors including dissolved oxygen concentrations and temperature. Consequently, the expected ocean deoxygenation and warming triggered by human-induced global change are considered as a serious threat to cold-water coral reefs. Here, we present results on recently discovered reefs in the SE Atlantic, where L. pertusa thrives in hypoxic and rather warm waters. This sheds new light on its capability to adapt to extreme conditions, which is facilitated by high surface ocean productivity, resulting in extensive food supply. Putting our data in an Atlantic-wide perspective clearly demonstrates L. pertusa’s ability to develop population-specific adaptations, which are up to now hardly considered in assessing its present and future distributions