Publications by authors named "Covadonga Orejas"

Article Synopsis
  • The bamboo-coral Isidella elongata is crucial for deep Mediterranean ecosystems and is considered critically endangered due to the negative effects of bottom trawling.
  • A modeling approach was used to map the coral's habitat suitability and assess the impacts of climate change and fishing practices, predicting a significant loss of suitable habitats (60% by 2100).
  • The study identifies critical areas for conservation efforts in the Mediterranean, linking them to EU biodiversity strategies and emphasizing the need to protect vulnerable marine ecosystems from fishing activities.
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Chilean Patagonia is a hotspot of biodiversity, harbouring cold-water corals (CWCs) that populate steep walls and overhangs of fjords and channels. Through anthropogenic activities such as deforestation, roadworks, aquafarming and increased landslide frequency, sediment input increases in the fjord region. While the absence of CWCs on moderately steep slopes has been suggested to reflect high vulnerability to sedimentation, experimental evidence has been lacking.

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The present study marks a pioneering investigation into the reproductive cycle of the scleractinian coral . This is one of the first reproduction studies conducted in the Mediterranean Sea for a colonial azooxanthellate coral. Coral samples were collected in 2017 (May and October) and 2018 (February and July) in the Alborán Sea (SW Mediterranean).

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Cold-water coral (CWC) reefs of the Angolan margin (SE Atlantic) are dominated by Desmophyllum pertusum and support a diverse community of associated fauna, despite hypoxic conditions. In this study, we use carbon and nitrogen stable isotope analyses (δC and δN) to decipher the trophic network of this relatively unknown CWC province. Although fresh phytodetritus is available to the reef, δN signatures indicate that CWCs (12.

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Article Synopsis
  • Cold-water coral reefs are rich in biodiversity, but there is limited understanding of how they develop in terms of morphology and the driving processes behind it.
  • A two-month study using flume experiments found that unidirectional water flow impacts coral growth and stress levels in Lophelia pertusa, with corals on the upstream side growing better due to higher current speeds and better food and ion intake.
  • The research indicates that local water flow conditions influence the morphology of coral reefs as they tend to grow towards the current, suggesting that coral distributions are a result of spatial self-organization influenced by hydrodynamic factors.
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  • Remote deep-ocean sediment ecosystems are largely unexplored, and previous genomic studies struggled to differentiate between native benthic organisms and falling plankton.
  • This research utilized global eukaryotic DNA metabarcoding data from various ocean depths to highlight that deep-ocean sediment biodiversity is at least three times richer than that in pelagic (open ocean) environments, with many unknown species.
  • The study found that benthic communities vary by ocean basin and are influenced by organic carbon flux, while plankton DNA indicates which species contribute to carbon export at the seafloor, revealing important ecological roles in the carbon cycle.
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Seafloor sediments cover the majority of planet Earth and microorganisms inhabiting these environments play a central role in marine biogeochemical cycles. Yet, description of the biogeography and distribution of sedimentary microbial life is still too sparse to evaluate the relative contribution of processes driving this distribution, such as the levels of drift, connectivity, and specialization. To address this question, we analyzed 210 archaeal and bacterial metabarcoding libraries from a standardized and horizon-resolved collection of sediment samples from 18 stations along a longitudinal gradient from the eastern Mediterranean to the western Atlantic.

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  • The study investigates the early life stages of a deep-sea octocoral species found in the Azores, focusing on its embryos and larvae under two different temperature conditions.
  • At 13 °C, embryos take 96 hours to reach the planula stage with a survival rate of 11 days, while at 15 °C, they develop faster in 72 hours and have a better median survival of 16 days, along with increased swimming speed.
  • The findings indicate that even slight temperature changes can significantly impact the development and dispersal potential of these corals, emphasizing the lack of existing knowledge on their early life stages which is vital for understanding deep-sea ecosystems.
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  • This study maps the occurrence and distribution of Madrepora oculata in coral mounds off Angola, highlighting its resilience in extreme hypoxic conditions.
  • Colonies reach up to 1250 mm in height and have a density of 0.53 colonies per square meter, comparable to populations in oxygen-rich areas.
  • The findings reveal that these coral colonies are relatively old, with an average age of about 95 years, and they are discussed in relation to existing knowledge from the North Atlantic and Mediterranean regions.
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We analyzed litter occurrence in 68 underwater video transects performed on the middle/outer continental shelf and submarine canyon off Cap de Creus (NW Mediterranean), an area recently declared Site of Community Importance (SCI). Low densities of urban litter were registered on the shelf (7.2 items ha), increasing in abundance towards the deepest part of the submarine canyon, with 188 items ha below 1000 m depth.

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The deep sea plays a critical role in global climate regulation through uptake and storage of heat and carbon dioxide. However, this regulating service causes warming, acidification and deoxygenation of deep waters, leading to decreased food availability at the seafloor. These changes and their projections are likely to affect productivity, biodiversity and distributions of deep-sea fauna, thereby compromising key ecosystem services.

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Sea-ice and coastal glacier loss in the Western Antarctic Peninsula open new ice-free areas. They allowing primary production and providing new seabed for colonisation, both acting as a negative feedback of climate change. However, the injection of sediment-laden runoff from the melting of land-terminating glaciers may reduce this feedback.

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Marine protected areas are considered a useful tool to preserve and recover the biodiversity of ecosystems. It is suggested that fisheries not only affect populations of target and bycatch species but also their parasite communities. Parasites can indicate fishery effects on host species and also on the whole local community, but the effects of fisheries and protection measures on parasite communities are relatively unknown.

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Coral growth patterns result from an interplay of coral biology and environmental conditions. In this study colony size and proportion of live and dead skeletons in the cold-water coral (CWC) (Linnaeus, 1758) were measured using video footage from Remotely Operated Vehicle (ROV) transects conducted at the inshore Mingulay Reef Complex (MRC) and at the offshore PISCES site (Rockall Bank) in the NE Atlantic. The main goal of this paper was to explore the development of a simple method to quantify coral growth and its potential application as an assessment tool of the health of these remote habitats.

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Article Synopsis
  • * Research on the cosmopolitan cold-water coral Desmophyllum dianthus shows that zooplankton is crucial for its physiological processes; the absence of zooplankton led to significant decreases in respiration and calcification rates.
  • * When fed, zooplankton supplied more than enough metabolic carbon for the corals, demonstrating their importance as a nutritional source and highlighting the corals' role as ecosystem engineers in deep-sea habitats.
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