Azorean deep-water coral communities as perceived from bottom long-line fishery surveys [poster communication at ICES Deep Sea Symposium, 2009] (original) (raw)
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Cold-water corals landed by bottom longline fisheries in the Azores (north-eastern Atlantic
The impact of bottom trawling on cold-water corals (CWC) has been thoroughly studied and shown to be long-lasting; however the effects of bottom longlining on CWC ecosystems have received little attention. The present paper identifies the principal CWC species landed by bottom longlining in Faial (Azores) from 150 to 600 m depth. Data were obtained from a survey of 297 landings during four months coupled with 16 interviews with fishermen. A distinction was made among corals brought on deck directly entangled in the fishing gear (primary by-catch) from corals brought up associated with other larger CWC species or rocks (secondary by-catch). Forty-five (15.2%) of 297 fishing trips surveyed landed coral specimens. The survey recorded 39 different CWC taxa in the by-catch, belonging to five different orders (Scleractinia, Alcyonacea, Antipatharia, Zoanthidea and Anthoathecata). Secondary by-catch included a larger number of species but the total number of corals was in the same order of magnitude for both groups. The taxa most frequently encountered were Leiopathes spp., Errina dabneyi and Dendrophyllia sp. CWC taxa in the by-catch were mostly medium size (10 – 60 cm), 3-dimensional and branched colonies. Local ecological knowledge of fishermen confirmed that the corals recorded were representative of their past experience and also revealed a general agreement that there has been a decrease of CWC by-catch on traditional fishing grounds. Corals are common by-catch in bottom longline fisheries around the Azores and so conservation measures may be required.
2013
Cold-water corals are widely considered as important structural components of benthic habitats, potentially enhancing local abundance in a variety of fish and invertebrate species. Yet, current knowledge of the taxonomic diversity and distribution patterns of these vulnerable, slow-growing organisms is scarce and fragmented, limiting the effectiveness of spatial management and conservation measures. We have conducted an exhaustive compilation of records of alcyonaceans, antipatharians, scleractinians and stylasterids available through present day to assess the diversity, distribution and spatial structure of coral assemblages in the Azores exclusive economic zone (EEZ). The resulting database comprises 2501 entries concerning historical oceanographic expeditions and other published sources, as well as unpublished data from bottom longline by-catch. Our taxonomic inventory appears to be fairly complete for the explored habitats, accounting for 164 species (79 alcyonaceans, 58 scleractinians, 18 antipatharians and 9 stylasterids), nine of which were documented for the first time. The Azores EEZ harbours a mixed coral fauna with several zoogeographic origins, showing the closest affinity with the Lusitanian–Mediterranean region. Very few apparent endemics were found (14 %), and only in part supported by consistent sampling. Coral diversity is particularly high between 300 and 900m depths, in areas recognized as traditional fishing grounds or exploitable fish habitat within the 100-mile limit of the EEZ. The composition of coral assemblages shows significant geographical structure among longitudinal sections of the study area at comparable depths (100–1500 m). There is no evidence of a possible role of the Mid-Atlantic Ridge or latitudinal effects underlying this pattern, which suggests that it may instead reflect assemblage variability among features. Stronger changes in species composition were found along the bathymetric gradient. Notwithstanding the mix of partially overlapping steno- and eurybathic species that characterize the vertical distribution of corals, there is a distinct transition from shallow (100–600 m) to intermediate (600– 1000 m) depths. The analysis presented here constitutes a valuable contribution for efficient conservation policies of coral-associated vulnerable marine ecosystems and their sustainable use as fishing areas.
Biogeosciences, 2013
We have conducted an exhaustive compilation of records of alcyonaceans, antipatharians, scleractinians and stylasterids available through present day to assess the diversity, distribution and spatial structure of coral assemblages in the Azores exclusive economic zone (EEZ). The resulting database comprises 2501 entries concerning historical oceanographic expeditions and other published sources, as well as unpublished data from bottom longline by-catch. Our taxonomic inventory appears to be fairly complete for the explored habitats, accounting for 164 species (79 alcyonaceans, 58 scleractinians, 18 antipatharians and 9 stylasterids), nine of which weredocumented for the first time. Very few apparent endemics were found (14%), and only in part supported by consistent sampling. Coral diversity is particularly high between 300 and 900m depths, in areas recognized as traditional fishing grounds or exploitable fish habitat within the 100-mile limit of the EEZ. Also, sample-based rarefaction curves for corals indicate that expected species richness is markedly lower in bottom longline than in trawled gears. The composition of coral assemblages shows significant geographical structure among longitudinal sections of the study area at comparable depths (100–1500m). There is no evidence of a possible role of the Mid-Atlantic Ridge or latitudinal effects underlying this pattern, which suggests that it may instead reflect assemblage variability among features. Stronger changes in species composition were found along the bathymetric gradient. Notwithstanding the mix of partially overlapping steno- and eurybathic species that characterize the vertical distribution of corals, there is a distinct transition from shallow (100–600m) to intermediate (600–1000m) depths.
Cataloguing deep-sea biological facies of the Azores
The Azores is an volcanic archipelago located in the northeast Atlantic approximately 1,600km westwards of Portugal’s mainland coast. Portugal’s marine jurisdiction around the islands encompasses an Exclusive Economic Zone of almost 1 million km2 and a claimed continental shelf extension that expands Portuguese sovereignty to approximately twice this value. The topographically-rich seafloor that surrounds the archipelago comprises a variety of open ocean deep-sea habitats, from island slopes and numerous seamounts to hydrothermal vents at various depths and abyssal plains exceeding 5,000m depth. This habitat mosaic holds a diversity of fauna including sensitive habitat-building deep-sea corals and sponges. However, literature is scarce on bathyal (200-2000m depth) and abyssal (2000-4000m depth) epibenthic biological assemblages encountered outside the minute hydrothermal vent fields. This paucity of information should be rapidly addressed in view of: (i) the shifting of fishing acti...
Biodiversity Information Science and Standards
The deep ocean is the largest and least explored biome with the highest richness of species and phylogenetic biodiversity on Earth. The high costs of using sophisticated technological means to access deep-sea ecosystems gives an inestimable value to specimens collected in these environments. Azorean scientists have long started collaborating with fishermen to collect deep-sea marine invertebrate fauna accidentally captured during fishing activities, thus obtaining deep-sea organisms opportunistically. Specimens have been stored and catalogued at the Department of Oceanography and Fisheries – University of the Azores’ Marine Biological Reference Collection (COLETA) since 2006. The collection has been continuously growing through oceanographic cruises and fisheries observer programs in the framework of several national and international collaborations. Currently, COLETA has 14367 specimens and samples corresponding to 10827 databased entries representing mostly corals (3415) and spong...