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Marine animal forest (MAF) are animal-dominated megabenthic communities that support high biodiversity levels and play key roles in ecosystem functioning. However, there is limited data available in Patagonian waters related to the presence of these vulnerable benthic communities. We report a monospecific MAF of Errina antartica in Angostura Tomms, which represents the southernmost known living MAF of this species. With coverages reaching up to 28.5% of the substrate from 1.23 m to, at least, 33 m depth is the shallowest stylasterid assemblage described worldwide to date. The size of the colonies ranged from 0.14 to 15.8 cm, with small colonies (< 10 cm) being the most abundant (99%). We hypothesize that this MAF might correspond to a recent colonization of a space, extending its distribution range towards shallower areas or it could be an assemblage formed at the limit of the species’ distribution in which the environmental conditions are not optimal for the major development of the colonies. Additionally, results showed that habitats structured by three-dimensional sessile invertebrate such as E. antarctica showed higher values of species richness and alpha diversity than non-biogenic habitats. Analyses were based on 297 photos taken at 22 different sites in the western Strait of Magellan, along vertical transects from 5 to 25 m depth. Our study highlights the importance of the benthic communities existing in Patagonian waters, evidencing the need to act actively to ensure their maintenance.

Antipatharians, also known as black corals, form three-dimensional habitats with high biodiversity from the infralittoral to the bathyal rocky bottoms of The Canary Islands. About thirty species belonging to this group have been found in this archipelago and surrounding areas. However, the taxonomic identification of some species still seems confusing, mainly due to their phenotypic plasticity. Therefore, the combination of morphological and genetic studies to support their identification is required. During a survey aboard the R/V Ángeles Alvariño conducted in 2022 in Special Areas of Conservation (SAC) at La Palma and El Hierro, the western islands of the Canary Archipelago, 23 specimens of black corals were collected with a remote operated vehicle. These samples, collected at depths between 120 and 531 m, were identified using morphological characters and molecular techniques (amplification and sequencing of 28S rRNA gene fragment). Although the results confirm the coincident morphological and molecular identifications for species of the genera Leiopathes or Antipathes, they show certain discrepancies in some taxa between the two approaches. Specifically, morphological features such as size, arrangement of the polyps and the shape of the spines, assign three samples to two different genera Antipathella and Tanacetipathes, while sequence homology to Genbank available sequences for Antipatharia and the phylogenetic analysis identified them as the same taxa. On the other hand, five collected specimens morphologically identified as Stichopathes spp. appear in two separate clades in the phylogenetic tree, being assigned to different genera by the molecular method, which confirms that the genus Stichopathes is a polyphyletic taxon, as previously reported (Bo et al., 2012). Further confirmation of the results presented here will be performed using mitochondrial markers. This study greatly contributes to clarify black corals taxonomy in The Canary Islands.

Indicators are key tools used to assess the ecological status of the environment for ecosystem based management. Anthropogenic disturbances produce changes to habitat condition, which include modifications in species composition and their functions. Monitoring a group of sentinel species (from a taxonomic and functional point of view) provides useful insights into benthic habitat condition. Here, a new indicator, Sentinels of the Seabed (SoS) is proposed to assess state of benthic habitats using “sentinel” species (species which are characteristic of a habitat and sensitive to a given pressure). The selection of these sentinel species has two stages. First, a ‘typical species set’ is computed using intra-habitat similarity and frequency under reference conditions. Second, the ‘sentinel species set’ is generated by selecting the most sensitive species from the typical species set. This selection is made using specific indexes able to assess species sensitivity to a particular pressure. The SoS indicator method was tested on six case studies and two different pressure types (trawling disturbance and pollution), using data from otter trawl, box-corer and Remote Operate Vehicle images. In each scenario, the SoS indicator was compared to the Shannon-Wiener diversity index, Margalef index and total biomass, being the only metric, which showed the expected significant negative response to pressure in all cases. Our results shows that SoS was highly effective in assessing benthic habitats status under both physical and chemical pressures, regardless of the sampling gear, the habitat, or the case study, showing a great potential to be a useful tool in the management of marine ecosystems.

The Northeast Atlantic, a highly productive maritime area, has been exposed to a wide range of direct human pressures, such as fishing, shipping, coastal development, pollution, and non-indigenous species (NIS) introductions, in addition to anthropogenically-driven global climate change. Nonetheless, this regional sea supports a high diversity of species and habitats, whose functioning provides a variety of ecosystem services, essential for human welfare. In 2017, OSPAR, the Northeast Atlantic Regional Seas Commission, delivered an assessment of marine biodiversity for the Northeast Atlantic. This assessment examined biodiversity indicators separately to identify changes in Northeast Atlantic biodiversity, but stopped short of determining the status of biodiversity for many species and habitats. Here, we expand on this work and for the first time, a semi-quantitative approach is applied to evaluate holistically the state of Northeast Atlantic marine biodiversity across marine food webs, from plankton to top predators, via fish, pelagic and benthic habitats, including xeno-biodiversity (i.e. NIS). Our analysis reveals widespread degradation in marine ecosystems and biodiversity, particularly for marine birds and coastal bottlenose dolphins, as well as for benthic habitats and fish in some regions. The poor biodiversity status of these ecosystem components is likely the result of cumulative effects of human activities, such as habitat destruction or disturbance, overexploitation, eutrophication, the introduction of NIS, and climate change. Bright spots are also revealed, such as recent signs of recovery in some fish and marine bird communities and recovery in harbour and grey seal populations and the condition of coastal benthic communities in some regions. The status of many indicators across all ecosystem components, but particularly for the novel pelagic habitats, food webs and NIS indicators, however, remains uncertain due to gaps in data, unclear pressure-state r

Indicators are key tools used to assess the ecological status of the environment for ecosystem based management. Anthropogenic disturbances produce changes to habitat condition, which include modifications in species composition and their functions. Monitoring a group of sentinel species (from a taxonomic and functional point of view) provides useful insights into benthic habitat condition. Here, a new indicator, Sentinels of the Seabed (SoS) is proposed to assess state of benthic habitats using “sentinel” species (species which are characteristic of a habitat and sensitive to a given pressure). The selection of these sentinel species has two stages. First, a ‘typical species set’ is computed using intra-habitat similarity and frequency under reference conditions. Second, the ‘sentinel species set’ is generated by selecting the most sensitive species from the typical species set. This selection is made using specific indexes able to assess species sensitivity to a particular pressure. The SoS indicator method was tested on six case studies and two different pressure types (trawling disturbance and pollution), using data from otter trawl, box-corer and Remote Operate Vehicle images. In each scenario, the SoS indicator was compared to the Shannon-Wiener diversity index, Margalef index and total biomass, being the only metric, which showed the expected significant negative response to pressure in all cases. Our results shows that SoS was highly effective in assessing benthic habitats status under both physical and chemical pressures, regardless of the sampling gear, the habitat, or the case study, showing a great potential to be a useful tool in the management of marine ecosystems.