| dc.description.abstract | The phylum Echinodermata represent a large part of the marine benthic ecosystem biomass (up to 90%), and are also important in determining habitat structure for other species, and maintaining high species diversity in the marine ecosystems. The phylum contains five classes (Asteroidea, Holothuroidea, Ophiuroidea, Crinoidea and Echinoidea), of which studies on both asteroids and holothuroids from the NE Atlantic Ocean are presented here. With the establishment of nations Exclusive Economic Zone at the end of the 1970s, nations acquired scientific responsibility for a larger area than previously controlled as well as the jurisdictionto governtheuseof their marine resources. Scarce knowledge on benthic fauna from the NE Atlantic Ocean (mainly before 1950), led to increased efforts in mapping biodiversity. In order to increase knowledge about invertebrates, including echinoderms, around the Faroe Islands, the «Marine benthic fauna of the Faroe Islands» (BIOFAR) programme was implemented. The programme conducted systematic sampling down to about 2400 m depth during the period between 1987 and 1990. Based on positive experience from BIOFAR, another programme, «Benthic Invertebrates of Icelandic Waters» (BIOICE), was formed a few years later, following somewhat the same principles. Data from both programmes, as well as a few other areas, are included in the studies on spatial distribution and abundance of Asteroidea, including taxonomic and molecular studies on Crossaster and Henricia genera, from the NE Atlantic Ocean.
Also, holothuroids (sea cucumbers) are considered a delicacy on the Chinese market, with increasing demand from consumers. With increasing interest for a Norwegian fishery on Parastichopus tremulus, but with limited knowledge on fishery, biology, production and the Chinese market, several pilot projects were begun. These projects took place along the Norwegian coast between 2000 and 2006, with follow up scientific cruises.
This doctoral thesis comprises three sub-aims, of which the first was to analyse distribution and abundance of asteroids from the NE Atlantic Ocean, using data obtained mainly from the Faroe Islands and Iceland. With the inclusion of asteroids from published literature, the total results show that 50 species have been recorded from the Faroe Islands, 64 from Iceland, and, although not included in these studies, 50 have been reported from nearby Norway, making Iceland the most species-rich area. Within the upper continental slope and the water mass transition zone, the most species-rich depth intervals from the Faroe Islands were identified with 33-34 species from 500-700 m depth. The two most species-rich depth intervals from Iceland showed only 23-24 species from 100-200 m and 400-500 m depth. All species showed different preferences regarding abundance-weighted depth- and temperature, although somewhat the same shallow-, intermediate- and deep-water species from the two programmes could be grouped. Non-metric Multidimensional Scaling (NMDS) from both programmes captured the same environmental gradients (depth and temperature). Asteroid accounts from the Faroe Islands and Iceland may become important basic reference data for future studies on climate change and shift in species distribution in these highly productive seas.
A second sub-aim of this study was to conduct in-depth analyses on two frequently encountered genera in the NE Atlantic Ocean (also the Faroe Islands and Iceland), Crossaster and Henricia, using both morphological and molecular methods. These genera are known for morphological variability and taxonomic confusion. Genetic analysis using DNA sequences COI and ITS1 supported the morphology studies indicating that C. papposus and C. squamatus are clearly distinct taxa, yet closely related. C. papposus is mainly found in temperate shallow waters, whereas C. squamatus is manly found on the shelf-break in colder, mixed water masses. Morphological studies on 796 Henricia specimens showed they could easily be assigned to either the «H. pertusa group» or «H. perforata group» mainly due to thorn- or blunt-shaped dorsal spines. Using DNA barcoding (COI and 16S regions), five well-supported genetic clades were revealed by maximum likelihood analysis. Re-evaluation of individuals from the different clades allowed us to confirm species identification for three of the clades: Henricia pertusa, H. perforata and H. oculata. Given the morphological variation within both Crossaster and Henricia genera, a combination of morphological and molecular studies is shown to be useful for species identification, and the methods are applicable for other studies aiming for a more accurate mapping of species richness and biodiversity. Diversity of asteroids is still poorly known and underestimated in certain areas of the world e.g. hampering the assessment of the origin and evolution of the class.
A third sub-aim of this thesis was to analyse Parastichopus tremulus data on catches, locations, length, sediment and market from a pool of sources, including pilot-projects with data obtained from fishing boats and by-catch fisheries from both northern and southern Norway, as well as scientific cruises. Results showed that P. tremulus is distributed all along the Norwegian coast, but with a patchy distribution, showing preference for gravelly sand. The largest trawl catches were taken from depths of ~100–300 m. Market analysis showed nutritional content were appreciated by Chinese customers, with a high protein and a low-fat content resembling levels of other holothuroids. High levels of polyunsaturated fatty acid EPA (eicosapentaenoic acid, C20:5 n-3, Omega 3) were specific for this cold-water species, in comparison to tropical species. Production and marketing tests showed a prosperous commercial potential on the Chinese market.
Overall, these advances in scientific knowledge have potential applications as baseline data for future studies on climate change, mapping of biodiversity and fishery. | en_US |
