THEME SESSION
on
Oceanography and Ecology of Seamounts–Indications of Unique Ecosystems (M)
ICES CM 2002/M:01
The influence of the Great Meteor Seamount on the distribution of phytoplankton
Manfred Kaufmann, Klaus von Bröckel, Christian Mohn, and Aike Beckmann
At the Great Meteor Seamount (GMS) (30oN 28.5oW) an extensive, interdisciplinary sampling was undertaken in September 1998 to detect the influence of this tablemount (min. depth 290 m) on the distribution of plankton and nekton organisms. Observations of the hydrography and the currents combined with a numerical model lead to the result that the dominant process at GMS was tidal forcing originating internal wave generation, trapped waves, flow rectification and a system of closed, horizontal and vertical circulation cells. These led apparently to an isolation of the phytoplankton community above the GMS summit as indicated by the distribution of various parameters, e.g., chlorophyll a (chl-a), photopigments and cell numbers obtained by flow cytometry. Chl-a showed a maximum over the summit which was slightly shallower (~80 m) than the deep-chlorophyll-maximum (DCM) at the off seamount stations (~100 m). Over the flanks there was a significant decrease in chl-a. Overall chl-a concentration was rather low not indicating an enhancement of phytoplankton standing stock induced by the GMS. photopigment analysis by HPLC and flow cytometry data indicated clearly a phytoplankton community dominated by cyanophytes (Synechococcus in the upper 80 m and Prochlorococcus around the DCM). In terms of biomass only a few thousand cells of picoeucaryotes dominated over the cyanophytes. The distribution of these picoplanktonic organisms also showed clearly isolated patches above the GMS summit linked to the closed circulation cells. These results were further confirmed by numerical modelling of lagrangian particle trajectories showing that passively advected organisms are likely to be retained in the near surface layers above GMS.
Keywords: seamounts, phytoplankton, picoplankton, Taylor column, patchiness, retention.
M. Kaufmann: University of Madeira, Department of Biology and Center of Macaronesian Studies, Marine Biology Station of Funchal, Cais do Carvão, 9000–107 Funchal/Madeira, Portugal [tel: +351 291 700360, fax: +351 291 766339, e-mail: [email protected]]. K. von Bröckel: Institut für Meereskunde, Universität Kiel, Düsternbrooker Weg 20, 24105 Kiel, Germany [tel: +49 431 600 4259, fax: +49 431 600 1515, e-mail: [email protected]]. C. Mohn and A. Beckmann: Alfred Wegener Institut für Polar- und Meeresforschung, Bussestraße 24, 27570 Bremerhaven, Germany [tel: +49 471 4831 1793, fax: +49 471 4831 1797, e-mail: [email protected], beckmann@awi- bremerhaven.de]
ICES CM 2002/M:02 Withdrawn
ICES CM 2002/M:03
Structure of waters and distribution of fishes at different ontogenetic stages around seamounts of the Central- Eastern Atlantic Ocean
A. G. Arkhipov, D. A. Kozlov, and E. V. Cherkashin
Seamounts’ fishery capacities depend on regional oceanographic features, causing formation of the high concentration of both phyto- and zooplankton, which attract planktivorous fish. Active spawning and juvenile foraging of these fishes occur there too. The material was collected in warm (2000) and in cold (2000–2001) years around seamounts of the South-Azores archipelago (29o–36oN; 27o–35oW). Areas of underwater heights are characterised by a complicate water dynamics, presence of both cyclonic and anti-cyclonic gyres, influencing biological productivity. In the considered area, cyclonic eddies prevailed in the summer, whereas in winter - anti-cyclonic ones. Complex of ichthyoplankton included 30 species of eggs and larvae of 16 fish families. A total of 22 species of eggs and larvae from 12 families were found in summer, and 20 species belonging to 11 families were identified in winter. Myctophidae and Gonostomatidae larvae predominated in both seasons, eggs of the Trachurus trachurus and Scomber japonicus were met more often in winter. Ichthyofauna of seamounts was represented in trawl catches by 51 species of fishes from 38 families. In summer, the mass species were Trachurus trachurus and Scomber japonicus, spawning Beryx splendens, Lepidopus caudatus, Antigonia capros, in by-catch there were found Myctophidae. In winter the spawning Trachurus trachurus and Scomber japonicus, Beryx splendens, Lepidopus caudatus predominated, Myctophidae and Gonos-tomatidae represented the by-
catch. It is noticeable, that the maximum abundance and diversity of ichthyoplankton, as well as greatest catches of adult fishes were found on seamount Erving, one of the largest in the area and characterised by complicate oceanographic features.
Keywords: seamounts, oceanography, productivity, fish eggs and larvae.
Corresponding author: A. G. Arkhipov, AtlantNIRO, Kaliningrad, Russia [e-mail: [email protected]]
ICES CM 2002/M:04
Tasmanian seamounts: diversity, biogeography, and benthopelagic connections
Alan Butler, C. Bulman, Xi He, T. Koslow, A. Williams, and S. Condie
Approximately 70 seamounts, 200–500 m high and rising from water depths of between 1000 and 2000m on the continental slope off southern Tasmania, support a distinct benthic community characterized by dense stands of the coral Solenosmilia variabilis, associated with diverse fish and invertebrates: of the 299 species recorded, between 31 and 48% are known only from this region. The fauna shows strikingly small affinity with those of the Norfolk Ridge and Lord Howe rise to the north. Some of the seamounts have been heavily trawled for orange roughy, but in May 1999 the Tasmanian Seamounts Marine Reserve was proclaimed by the Australian Commonwealth Government; it protects a group of about 14 seamounts, peaking at depths of 1100–1700 m. The upper 500 m of the water column within the Reserve is managed as an IUCN Category VI Managed Resource Zone, in which pelagic fishing is permitted. Below 500 m depth is an IUCN Category IA Highly Protected Zone, in which all fishing and petroleum or mineral extraction is prohibited. The decision to zone the Reserve in this way was justified by the distinct physical water masses and biological communities in these two zones. However, this paper discusses current research using dynamic models to address two issues. The first is the possibility of significant trophic connection between the surface and demersal systems, due to diel vertical migration by some mesopelagic fishes. The second is the likely importance of energy inputs, mostly through horizontal advection, required to sustain the demersal fish community.
Keywords: seamount biodiversity, endemism, trophodynamics, bentho-pelagic connections, effects of fishing.
A. Butler, C. Bulman, Xi He, A. Williams, T. Koslow, and S. Condie: CSIRO Marine Research, GPO Box 1538 Hobart, Tasmania, 7001, Australia [tel: +61 3 6232 5491, fax: +61 3 6232 5053, e-mail: [email protected]]. Present addresses: T. Koslow: CSIRO Marine Research, Perth, Western Australia, Xi He: Southwest Fisheries Science Center, Santa Cruz Laboratory, 110 Shaffer Road, Santa Cruz, CA 95060, USA
ICES CM 2002/M:05
Ichthyofauna research on underwater mountains within the North-Atlantic Ridge and adjacent areas
E. I. Kukuev
From the mid-1970s to the late 1980s the active fishery researches aimed at revealing the fishery potential of ichthyofauna associated with the North-Atlantic ridge and adjacent areas were carried out by AtlantNIRO and Zaprybpromrazvedka. These researches included species composition and zoogeographic structure of ichthyofauna associated with the North-Atlantic ridge and other underwater mountains. In the work the data on ichthyofauna species composition of the northern part of the North-Atlantic ridge (43–57oN, 28–34oW), corner Mountains (34–35oN, 48– 52oW), underwater mountains (guyots) southwards of Azores (28–32oN 30–34oW) and Rockall underwater mountains are presented based on considerable sampling material (about 200 species). Peaks of high mountains (minimum depths up to 300 m), located eastwards of the Mid-Atlantic ridge (Rockall and the underwater mountains southwards of Azores), are inhabited by bottom ichthyofauna associated with the European and North-African shelf. In this area the East-Atlantic species significantly prevail as compared to amphi-Atlantic and common tropical forms. On the Rockall plateau boreal and boreal-tropical European species prevail, while on the underwater mountains southwards of Azores the north-subtropical, boreal-subtropical and common tropical East-Atlantic species typical of the shelf of the Southern Europe and North-west Africa predominate. At mesobenthonic depths (more than 500m) the pattern of zoogeographic structure changes with ichthyofauna species composition variations. The ichthyofauna acquires a similar pattern irrespective of the geographical location on the Mid-Atlantic ridge westwards or eastwards of it. Everywhere at these depth levels common tropical, amphi-Atlantic and boreal-subtropical species predominate considerably. The number of East-Atlantic species is insignificant as compared to the above categories, though the increase of the East-Atlantic species is observed at the slope of the Rockall plateau and underwater mountains southwards of Azores, as well as the
increase of common tropical species in corner Mountains and the Mid-Atlantic ridge. The West-Atlantic fauna component on the peaks and slopes of the mountains investigated is small, and even on corner Mountains located westwards of the Mid-Atlantic ridge the proportion of East-Atlantic species is twice that of West-Atlantic species (8:4). At mesobenthonic depths (more than 500m) in all areas bathyal-pelagic fishes considerably predominate as compared to the bottom types both by species diversity and biomass.
Keywords: species diversity, comparison boreal vs. tropical.
E. I. Kukuev: Atlantic Scientific Research Institute of Marine Fisheries and Oceanography (AtlantNIRO), 5, Dm.Donskoy Str., Kaliningrad, 236000, Russia [tel: +7 0112 225 416, fax: +7 0112 219997, e-mail: [email protected] or [email protected]]
ICES CM 2002/M:06 Withdrawn
Rare benthopelagic calanoid copepods from the Great Meteor Seamount (Northern Atlantic)
Elena L. Markhaseva and Sigrid Schiel
Nine benthopelagic calanoid taxa that belong to 7 genera were found in 11 samples collected at the Great Meteor Seamount (Northern Atlantic) at depths from 295 to 560 m by Epibenthic Sledge in RV Meteor cruise in 1998. Of these 5 are identified to the species level (Bradyidius armatus, B.luluae, Paracomantenna minor, Tharybis macrophthalma and Paramisophria spooneri (?)). An unknown earlier male of P. minor was found and described for the first time for the genus Paracomantenna. Data on P. minor male morphology will contribute much to the understanding of the phylogenetic interrelations in the family Aetideidae. Representatives of the remaining rare hyperbenthic calanoids found in the samples: Metacalanus sp., Pseudocyclopia sp., Xanthocalanus sp. and Paramisophria spooneri need further detailed and careful taxonomic study. The preliminary analysis of their morphology demonstrated significant differences in diagnostic characters with the earlier described species of the above mentioned genera. It is very probable that they are new species. B. armatus and T. macrophthalma were most abundant (found in 9 samples and 10 samples, reaching to 189 and 22 adult specimens respectively). Both species are typical component of benthopelagic fauna of the Norwegian waters (Sars 1902, 1903; Mattews, 1964). A similarity of the fauna of benthopelagic calanoids found at the Great Meteor Seamount (Northern Atlantic) and the fauna of benthopelagic species of Norwegian waters on the species/genus level was observed.
Keywords: copepods, rare and new species, Great Meteor Seamount.
E. L. Markhaseva: Zoological Institute, Russian Academy of Sciences, Universitetskaya nab. 1, St. Petersburg 199034, Russia [e-mail: [email protected]]. S. Schiel: Alfred-Wegener-Institut fur Polar und Meeresforschung, Columbusstrasse, D-27568, Bremerhaven, Germany [e-mail: [email protected]]
ICES CM 2002/M:07
Seamounts, hotspots for high speciation rates in bentho-pelagic fishes? A case study on Macroramphosus spp. (Syngnathidae) on Great Meteor Seamount
Birte Matthiessen
Snipefishes of the genus Macroramphosus (Syngnathidae) represent one of the most abundant demersal fish on Great Meteor Seamount (GMR, subtropical NE Atlantic, 30oN, 28.5oW). High morphological variability within the genus makes it uncertain whether Macroramphosus is represented by one or more species. The question whether isolated seamounts are possible sites of increased speciation rates, gave us reason to examine 202 individuals of Macroramphosus spp. regarding diet composition and morphology. Of these, 50 specimens belonged to the deep-bodied benthos feeding type (b-types) whose diet consisted of foraminiferans, pteropods, decapods and polychaetes, whereas the slender planktivorous individuals (p-types, n=140) mainly fed on ostracods, copepods, pteropods and foraminifers. Twelve specimens showed no feeding-related specialization (p/b-types). Both feeding types can be significantly discriminated by means of bi- and multivariate morphological analysis considering the variables body depth, length of second dorsal spine, diameter of orbit, and standard length. Despite similar observations on snipefishes from non- isolated habitats from the Pacific, our results suggest that isolated Seamounts may represent hot spots of speciation where special selection pressure is favouring the evolution of two ecological divergent species within the genus Macroramphosus.
Keywords: Macroramphosus spp., Great Meteor Seamount, speciation, sympatric species, isolated habitat, habitat partitioning.
B. Matthiessen: Alfred-Wegener-Institut für Polar- und Meeresforschung, Am Handelshafen 12, D-27570 Bremerhaven, Germany [tel: + 49 0471 4831 1384, e-mail: [email protected]]
ICES CM 2002/M:08
Challenges and problems in modelling seamount ecosystems and their fisheries
Telmo Morato and Tony Pitcher
The ecological and oceanographic importance of seamounts for the status of marine food webs and biodiversity has recently been recognized. Seamounts have been intensively exploited in all world oceans, and serious stock depletion has been detected in every case. Resident seamount fish are mostly slow-growing and late-reproducing while transient migratory fish also rely on seamount food webs, so that the impact of overfishing raises serious concerns. Moreover, trawling threatens the integrity of benthic habitats. The prevention of further negative impacts on these sensitive ecosystems is now an important policy objective. Because of the extensive trophic links on seamounts, ecosystem-based modelling approaches are essential to understand the ecosystem functioning and to ensure an effective management. However, there have been few attempts to model seamount communities. This talk will discuss the problems associated with modelling seamount ecosystems using the Ecopath-with-Ecosim framework. We propose modelling approaches to seamount processes such as the influences of peculiar current patterns on the seamount system, complex food web structure depending on advective food supplies, predation by transient visitors like tuna and whales, and the integration of different environmental compartments stratified by depth. With a history of unremitting serial depletion, we use the model to ask what types of fisheries might be sustainable on seamounts.
Keywords: seamounts, trophic models, Ecopath, Ecosim, ecosystem-based management.
T. Morato and T. Pitcher: Fisheries Center, University of British Columbia, 2204 Main Mall, Vancouver, British Columbia, V6T 1Z4, Canada [tel: +1 604 822 0294, fax: +1 604 822 8934, e-mail: [email protected]]. T. Morato also from: Departamento de Oceanografia e Pescas, Universidade dos Açores, PT- 9901–862, Horta, Portugal [tel: +351 292 292988, fax: +351 292 292659, e-mail: [email protected]]
ICES CM 2002/M:09
Deep scattering layer over Reykjanes Ridge and in the Irminger Sea
Th. Sigurðsson, G. Jónsson, and J. Pálsson
In recent years, Iceland has conducted several trawl-acoustic surveys in the Irminger Sea and adjacent waters. The target species for investigations has been pelagic redfish (Sebastes mentella), but all specimens caught have been measured and/or counted. In addition to the redfish, the catch has consisted of numerous species of fishes with a modal length between 10 and 20 cm. In all the surveys, an extensive deep-scattering layer has been observed, mostly in the depth layer between 300–800 m. In this paper, we show distribution and composition of the deep-scattering layer, based on combined information since 1996. Myctiphids are the most common group of organisms that are caught in the “Gloria type” trawl used (40 mm codend). Most common fishes (excluding the redfish) are Lampanyctus macdonaldi, Myctophum punctatum, Notoscopelus kroeyeri, Lampadena speculigera, Benthosema glaciale and Protomyctophum arcticum. Other small fishes caught are, inter alia, Bathylagus euryops, Gonostomatidae, Chauliodus sloani, Stomias boa ferox, Serrivomer beani Melamphaeidae, Borostomias antarcticus, Platytroctidae, Nemichthys scolopaceus, Xenodermichthys copei, Sternoptychidae and others.
Keywords: scattering layer, Irminger Sea, food web.
Th. Sigurðsson, G. Jónsson, and J. Pálsson: Marine Research Institute, Skúlagata 4, P.O. Box 1390, 121 Reykjavík, Iceland [e-mail: [email protected]]
ICES CM 2002/M:10
Interaction of mesopelagic fish and shallow topography in different latitudes of the NE Atlantic
Christian Pusch, H. Fock, Filipe Porteiro, and H. von Westernhagen
Mesopelagic fishes represent an important faunal element of the micronecton community of oceanic ecosystems. The interaction of vertical migrating fish and submerged features like seamounts, islands and ridges is poorly understood. The effects of shallow bottom topography on the distribution of mesopelagic fish were investigated in four areas of the temperate and subtropical NE Atlantic. For this purpose the micronekton community was sampled in each area over three different bathymetric depth zones with stratified midwater trawl tows. The following aspects have been investigated (1) Zoogeographic changes of the mesopelagic fish community on a latitudinal gradient from 44o to 30oN (2) The question: Is there a distinct mesopelagic boundary community associated with submerged features, regarding taxonomic composition and diversity? (3) The effects of bottom topography (i.e., decreasing depth) on the finescale distribution of the mesopelagic fish assemblages. It is expected that the biomass of micronektonic fish is reduced over the seamount summits, either by the disturbance of the diurnal vertical migration or by predation of benthopelagic fish. The knowledge of the standing stock of mesopelagic fish is a valuable requisite for the understanding of the food web structure of seamount ecosystems.
Keywords: NE Atlantic, mesopelagic fish, zoogeography, seamounts, finescale distribution.
C. Pusch, H. Fock, and H. von Westernhagen: Alfred-Wegener-Institut for Polar and Marine Research, Columbusstrasse, 27568 Bremerhaven, Germany [tel: +49 (0)471 48310, e-mail: [email protected], [email protected], [email protected]]. F. Porteiro: Departamento de Oceanografia e Pescas, Universidade dos Acores, PT-9901862 Horta, Portugal [e-mail: [email protected]]
ICES CM 2002/M:11 Withdrawn
Biodiversity of the macroinvertebrate assemblages of the Kermadec volcanic arc seamounts: evidence for the stepping-stone theory and the influence of geologic history
A.A. Rowden, S. O’Shea, D.G. McKnight, and M.R. Clark
Seamounts are prominent and widely distributed features of the New Zealand marine environment, and also the focus of important commercial fisheries and some exploratory mineral mining. Scientists in New Zealand are involved in a number of integrated programmes to study the physical and biological processes of seamounts. Since 1998 seamount biodiversity has received particular attention. Most recently, sampling has been undertaken of submarine volcanos associated with the Kermadec volcanic arc, a >1000 km sector of the convergent Pacific – Australian plate boundary. Twelve of these linearly arranged seamounts (between 30º–37ºS), five of which have active hydrothermal vents, were sampled in 2001/02. Sampling consisted of multi-beam swath mapping, camera and video survey, and towed rock dredges and epibenthic sleds to recover substrate and associated biotic assemblages. Data from this study that describes the macroinvertebrate assemblage composition, and the age, origin and geochemical characteristics of the seabed, allows for some of the persistent questions in seamount ecology to be addressed. In particular, do seamounts provide stepping-stones for dispersal of biota?, and what effect does the geologic history of a seamount have on the composition of its biota? The preliminary results of this study will be presented with respect to these questions.
Keywords: fisheries, exploratory mining, biodiversity, stepping-stone theory.
Corresponding author: A. A. Rowden: National Institute of Water and Atmospheric Research, PO Box 14–901, Kilbernie, Wellington, New Zealand [e-mail: [email protected]]
ICES CM 2002/M:12
Composition of ichthyoplankton and horizontal and vertical distribution of fish larvae taxa in the Great Meteor Seamount area in September 1998
Walter Nellen and S. Ruseler
24 stations above and near the Great Meteor Seamount, central north Atlantic, have been sampled at eight depth strata in late summer 1998 by a modified MOCNESS. Some 18.800 fish larvae were collected and specimens were identified
to species and coarser systematic levels, respectively. Taxa typical of the high sea remote from coastal areas dominated the fish larvae assembly. But species which normally are found on the shelf or slope occurred as well in the plankton samples, mainly above and fairly close to the 300 m deep seamount obviously keeping away from the oceanic region several thousand meters deep. Eighteen of the total of more than 100 identified larvae were fish taxa belonging to the neritic province. One of these species was the third most abundant larvae found so far during this investigation, namely Chlorophthalmus agassizii. Concentration and horizontal and vertical distribution of selected species, will be discussed as well as migration behaviour in dependence of day and night situation and sea bottom depth. It will be considered whether this seamount may be regarded as an isolated, just 1465km² large shallow water area settled permanently by a coastal fish community. The question will be treated why this may be so, i.e., which kind of non biotic and biotic factors could be responsible for such a situation.
Keywords: fish larvae, Great Meteor Seamount, systematics, settlement.
Corresponding author: W. Nellen: Institut für Hydrobiologie und Fischereiwissenschaft, University Hamburg, Olbersweg 24, 22767 Hamburg, Germany [e-mail: [email protected]]
ICES CM 2002/M:13
Distribution of epibenthic communities on the Great Meteor Seamount (NE Atlantic) mirrors water-column processes
Dieter Piepenburg and Bernard Müller
Seabed photographs taken at 15 stations at water depths of 290 to 600 m in August to September 1998 were quantitatively analysed for abundance, diversity and distribution patterns of epibenthic organisms on the Great Meteor Seamount (NE Atlantic). The results clearly show that invertebrate epifauna is rather poor in both abundance and diversity. Many photographs showed no or only few epibenthic organisms. Mean abundances per station fell into the range from 0.03 to 55.6 ind. m-2. A total of 53 putative species were identified in the photographs. Species numbers per station varied between 12 and 22. Most prominent megafaunal taxa were sponges (e.g., Haliclona sp.), gorgonarian species (e.g., Elisella flagellum), antipatharian (e.g., Antipathes glabberima) and madreporarian corals (e.g., Dendrophyllia cf. corniger), and sea urchins (Cidaris cidaris). Small-scale distribution patterns (within-station, i.e., at a10-m scale) were characterized by a pronounced patchiness in the occurrence of dominant species. The meso-scale pattern (between-stations, i.e., at a 10-km scale) discriminated by multivariate statistics featured three distinct faunistic zones: the Slope (> 450 m), a Southern Plateau (290 to 300 m), and a Northern Plateau (290 to 470 m). This pattern corresponds well with the distribution of topography-driven gyres over the seamount, locally augmenting pelagic primary production, sedimentation and, hence, food supply to the benthos.
Keywords: Great Meteor Seamount, benthic community photography, diversity.
D. Piepenburg and B. Müller: Institut für Polarökologie Universität Kiel Wischhofstr. 1–3, Geb. 12, 24148 Kiel, Germany [e-mail: [email protected]]
ICES CM 2002/M:14
Conservation of Seamount Ecosystems: application of an MPA concept
Paul Johnston and David Santillo
Scientific appreciation of the unique properties of seamount ecosystems has grown markedly in recent years. With this growing body of knowledge has come the realisation that the targeting of fish populations supported by these ecosystems is inherently unsustainable. For the most part, the target species are long-lived and slow to mature, with low fecundity. At current levels of exploitation, populations of some are showing signs of reduced genetic diversity. The exploitation of seamount fish stocks also seriously impacts the benthic communities disturbed by the fishing gears employed in the industry. Benthic communities could also be seriously disturbed by exploitation of marine mineral resources At current levels of knowledge concerning the structure and integration of seamount ecosystems, it is not possible to envisage that these systems can be exploited in a sustainable manner. Accordingly, a holistic and precautionary conservation strategy is required. This paper explores the elements of a conservation strategy based upon defining seamounts as fishery no-take zones and as areas protected from the full spectrum of anthropogenic activities. Given the apparent individual character of the seamount systems studied to date, this paper makes the case that a protective regime should encompass all seamounts to conserve biodiversity globally.
P. Johnston and D. Santillo: Greenpeace Research Laboratories, University of Exeter, Prince of Wales Road, Exeter, EX4 4PS, United Kingdom [e-mail: [email protected]]
ICES CM 2002/M:15
Using SeamountsOnline, a biogeographic information system for seamounts, to examine patterns in seamount endemism
Karen I. Stocks
SeamountOnline is a project compiling existing information on the biota and environments of seamounts globally and making it freely available through a web-based portal. The system contains records of species- or genus-level observations from seamounts, and includes a breadth of metazoan taxa. The current contents of the system will be briefly described, including how data can be searched, viewed and downloaded through the interactive web site (http://seamounts.sdsc.edu), and its research and management uses and limitations will be discussed. Seamounts, with their high but varying levels of biodiversity and endemism, are good case studies for understanding processes that promote and maintain diversity in the oceans. To display the abilities of the system in investigating large-scale patterns in biogeography, the distribution and endemism patterns of fish and crustaceans on two seamount chains, the Nazca/Sala y Gomez and the Hawaiian/Emperor, are described and compared to the results of Richer de Forges et al. from New Caledonia seamounts. The performance of island biogeography theory in relating levels of endemism to distance from like habitat and habitat area is discusses for each chain.
K. I. Stocks: San Diego Supercomputer Center and Scripps Institution of Oceanography UC San Diego, MC 0505, 9500 Gilman Drive, La Jolla, CA 92093 USA [tel: +1 858 534–5009, fax: +1 858 822–3631, e-mail: [email protected]]
ICES CM 2002/M:16 Withdrawn
Fish larvae community and zooplankton biomass around a seamount with shallow-water hydrothermal vents from the Azores archipelago
Luis Sobrinho-Gonçalves and Frederico Cardigos
In August 2000, ten plankton hauls were performed above and around shallow-water hydrothermal vents located at D. João de Castro seamount (Azores archipelago, NE Atlantic), down to 100m deep, covering different distances to the crown. In all, 1814 fish larvae were counted, from which 35 taxa were identified, belonging to 7 families. The fish larvae community was completely dominated (89%) by mesopelagic elements pertaining to Myctophidae (Ceratoscopelus maderensis constituting 45% of the sample) and Gonostomatidae, revealing a typical oceanic seamount environment composition. Regarding mesozooplankton, we did not find a significant spatial density gradient with the crown’s proximity, even if the community aggregated at the most distant stations from the seamount (2,548 gr/100m3). Unlike other equivalent studies, we did not find a significant relationship between the mesozooplankton biomass and the fish larvae community density. C. maderensis was the only fish larvae taxon displaying a significant correlation with the seamount’s proximity, reaching the maximum above the summit (37,3 ind./100m3) where the captured individuals were significantly larger than in other stations, suggesting that this seamount is important for this species’ reproductive ecology. Despite of this seamount’s location between two major islands, there was no evidence of a “stepping stone” effect concerning coastal fish species.
Keywords: Fish larvae, mesopelagic elements, plankton biomass, reproductive ecology, stepping-stones.
L. Sobrinho-Gonçalves and F. Cardigos: Departamento de Oceanografia e Pescas da Universidade do Açores, Acores, Portugal [e-mail: [email protected]]
ICES CM 2002/M:17
Species composition and distribution patterns of early life stages of cephalopods at Great Meteor Seamount (subtropical NE Atlantic)
Rabea Diekmann and Uwe Piatkowski
The distribution of early life stages of cephalopods was studied during a cruise of RV Meteor in September 1998 at Great Meteor Seamount, an isolated flat-topped seamount in the subtropical eastern North Atlantic. Zooplankton sampling was conducted with a vertically resolving multi-opening-closing-net (BIOMOC, 1m² net opening, 335µm mesh size) between 290m depth and the surface. 1180 early life stages of cephalopods were collected representing at least 17 families and 33 mainly oceanic species. Most of the identified cephalopods comprised mesopelagic species (e.g., representatives of the families Enoploteuthidae and Pyroteuthidae) that proved to carry out diurnal vertical migrations even at the youngest stages. Hydrographic measurements revealed slow anticyclonic recirculation around the seamount forming a Taylor column and, thus, some retention potential for passive tracers. Nevertheless, multivariate statistical analyses revealed no differences in the cephalopod community in the proximity to the summit compared to the adjacent oceanic regions. This was partly related to the great depth of the plateau (< 300m) and, therefore, a hardly enhanced primary production as well as the lower retention potential for active vertical migrators. Indications on daily gap formation of these species over the summit of the seamount were revealed.
Keywords: Cephalopoda, Great Meteor Seamount, species composition, distribution, retention potential, diurnal vertical migration.
R. Diekmann: Institut für Meereskunde Kiel, Duesternbrooker Weg 20, 24105 Kiel, Germany [tel: +49 431 600 4559, fax: +49 431 600 4553, e-mail: [email protected]]. U. Piatkowski: Institut für Meereskunde Kiel, Duesternbrooker Weg 20, 24105 Kiel, Germany [tel: +49 431 600 4571, fax: +49 431 600 4553, e-mail: [email protected]]
ICES CM 2002/M:18
The impact of the Great Meteor Seamount (NE Atlantic) on the nutritional condition of larval Vinciguerria nimbaria (Photichthyidae) - a histological study
Frank Hartmann
Fish larvae were sampled at 26 stations on the Great Meteor Seamount from August to September 1998 as part of a programme to investigate whether species composition, densities and nutritional condition of the zoo- and ichthyoplankton will be affected by the seamount. A total of 664 individuals of the ten dominant fish taxa were investigated. Histological analyses of the larvae were carried out as a measure of nutritional condition. As indicators the quantities of the intracellular glycogen in the hepatocytes, the height of the mid gut mucosa, and the fine structure of the above mentioned tissues were consulted. Nutritional conditions, standard lengths, and developmental stages of the larvae were examined and statistically compared with regard to the three seamount areas, plateau, transition zone and oceanic zone, proposed by the results of the oceanographic modelling. No differences of the nutritional state were observed between those fish larvae caught above the seamount plateau and those from the oceanic zone. But in both regions, fish larvae were predominantly better nourished than in the transition zone. The results of a cluster analysis, which estimated the nutritional condition of the most frequent larvae of Vinciguerria nimbaria at the particular catch stations, revealed that the anticyclonically streaming water body of the transition zone has to be differentiated into two sections. The section situated in the east of the plateau obviously offers favourable nutritional conditions to the ichthyoplankton, which corresponds to those of the plateau and the oceanic zone. Fish larvae from the section in the west were in the poorest condition of all fish investigated. These results were compared and discussed with the results of the zooplankton investigations and biochemical investigations (RNA/DNA relationship) of fish larvae. On the basis of the available results, the initially stated hypothesis, that the retention area over the seamount offers more favourable nourishing conditions to the fish larvae than the deep-sea area, has to be rejected.
Keywords: fish larvae, nutritional condition, Vinciguerria nimbaria.
F. Hartmann: Institut für Hydrobiologie und Fischereiwissenschaft, Universität Hamburg, Olbersweg 24, 22767 Hamburg, Germany [tel: +49 (0)40 428386604 /-6625, fax: +49 (0)40 428386618, e-mail: fhartmann@uni- hamburg.de]
ICES CM 2002/M:19 (Poster)
Benthic foraminifera communities at seamount “Great Meteorbank”
Petra Heinz, D. Ruepp, and Ch. Hemleben
Benthic foraminifera are among the most abundant organisms living in deep-sea sediments. Their species composition, abundance and distributional pattern mainly depend on environmental factors, e.g., such as food supply. Seamounts show a high variability of environmental conditions, like water depth, temperature, current systems, trophic conditions, and sediments, at a rather small scale. This can lead to the formation of ecological niches and a biological zoning. Sediment sampling on several transects at the seamount “Great Meteorbank” (eastern North Atlantic) in August 1998 enabled us to compare communities of living benthic foraminifera from the plateau of the “Meteorbank” (250–500 m water depth) and from the abyssal plain surrounding the seamount (2700–4100 m). No particular shallow water species were observed at the plateau. Most stations showed low abundance of foraminifera, but high species diversity. Both indicate oligotrophic conditions in this area. High oxygen content in the sediment at the deep stations and low organic carbon values at all stations confirm this. In average, we found more living individuals at the deeper stations in the first centimetre, especially in the North and Northwest of the Bank. Changing trophic conditions, depending on changing hydrographic conditions, may explain differences in occurrence pattern.
Keywords: Northeast Atlantic, recent benthic foraminifera, seamounts, Great Meteorbank.
P. Heinz, D. Ruepp, and Ch. Hemleben: Institute of Geology and Paleontology, University of Tübingen, Sigwartstr. 10, 72076 Tübingen, Germany [tel: +49 7071 29 74683, fax: +49 7071 29 5766, e-mail: [email protected]]
ICES CM 2002/M:20
The upper ocean circulation at Great Meteor Seamount Part I: structure of density and flow fields
Christian Mohn and Aike Beckmann
Many seamounts are known as oceanic areas with increased biomass and biodiversity. There are strong indications that the biogeochemical dispersion patterns are profoundly influenced by physical processes and phenomena (upwelling, turbulent mixing, closed circulation cells). Observations of the hydrography and currents at the Great Meteor Seamount, one of the largest isolated submarine features in the Atlantic Ocean, are combined with a numerical model to investigate the three-dimensional structure of the flow regime at this seamount. Several aspects of the physical situation at Great Meteor Seamount make it particularly worth studying: its strong asymmetric topography, its geographical position centred at the critical latitude for the diurnal K1 tides and the importance of both diurnal and semidiurnal tides. To take into account these aspects in the model simulations, a high resolution and a combined sub- and superinertial forcing on a beta-plane were introduced. Signatures of waves and mean flow were separated and interpreted. Tidal forcing is the dominant process in the area, leading to internal wave generation, trapped waves, flow rectification and a system of closed circulation cells (horizontal and vertical). The steep slopes and the flat summit plain lead to a previously unreported mixed layer thickness anomaly along the edge of the seamount.
Keywords: seamounts, hydrography.
C. Mohn: Max Planck Institute for Meteorology, Bundesstraße 55, D-20146 Hamburg, Germany [tel: +49 (0)40 41173 431, fax: +49 (0)40 41173 476 e-mail: [email protected]]. A. Beckmann: Alfred-Wegener Institute for Polar and Marine Research, D-27515 Bremerhaven, Germany [tel: +49 471 4831 1793, fax: +49 471 4831 1797, e-mail: [email protected]]
ICES CM 2002/M:21
Does the Great Meteor Seamount affect growth and condition of fish larva with special reference to Vinciguerria nimbaria?
Catriona Clemmesen and H. Röhrscheidt
Fish larvae of the species Vincigueria nimbaria, a dominant species in the ichthyoplankton samples caught on a cruise in August/September 1998 on the plateau and the deep water area around the Great Meteor Seamount were analysed for nutritional condition and growth based on RNA/DNA ratios, size in length and dryweight and otolith increment pattern.
Data analysis was based on following hypothesis: 1) Due to its oceanographic features (Taylor column, retention area) the Great Meteor Seamount favours growth and nutritional condition for larval fish. 2) Growth and age patterns above and around the seamount are influenced by the cyclic flow patterns. Results show that Vinciguerria larvae caught on the plateau of the seamount showed significantly larger sizes and dry weights compared to the oceanic zone although the nutritional condition as measured by RNA/DNA ratios indicated higher RNA/DNA values and therefore better conditioned larvae from the oceanic zone. Age structure analysis based on otolith increments indicated no significant differences between the sampling areas. Although the oceanographic features (Taylor column and retention situation) could have favoured the feeding and growing situation for the larvae on the plateau of the Meteor Seamount, the best- conditioned larvae were found in the oceanic zone rejecting the hypothesis of an “Island in the ocean”.
Keywords: fish larvae, growth, condition, RNA/DNA, Vinciguerria nimbaria.
Corresponding author: C. Clemmesen: Institut für Meereskunde an der Universität Kiel, Düsternbrooker Weg 20, 24105 Kiel, Germany [e-mail: [email protected]]
ICES CM 2002/M:22
Harpacticoida (Crustacea, Copepoda) of the Great Meteor Seamount, with first conclusions as to the origin of the plateau fauna
Kai Horst George and Horst Kurt Schminke
Qualitative samples were taken in 26 stations on the Great Meteor Seamount and in the surrounding deep sea in order to register the complete meiofauna and to allow first qualitative faunistic investigations. Among the 26 taxa of meiofauna found nematodes and copepods were the most abundant ones. Study of the Copepoda Harpacticoida yielded 28 supraspecific taxa, of which 11 have been selected for further investigations at the species level. Of the 56 species determined 54 are new to science. Two separate faunas can be distinguished: one on the plateau (29 species) and one in the surrounding deep sea (23 species). The number of overlapping species, i.e., recorded in both areas, is rather low (3 species). The high number of new species can be taken as a sign of pronounced endemism.
Corresponding author: K. H. Georg [e-mail: [email protected]]
ICES CM 2002/M:23 Withdrawn
Demersal fish assemblages in the Cape Verde Archipelago: changes over the period 1981 to 1994 and a comparison with the northwest African continent
Kim A. Stobberup, Patricia Amorim, and Oksana Tariche
The Cape Verde Archipelago consists of ten islands of volcanic origin, located 600 km west off the coast of Senegal. These islands are characterised by very narrow continental shelves and steep slopes down to at least 4000 m. The eastern islands Sal, Boavista, and Maio form one system with an area of 1315 nm2, where several trawl surveys have taken place. The structure of demersal fish assemblages was studied based on available data, which are the trawl surveys undertaken in 1981, 1985, 1988, and 1994. Multivariate analysis, using non-parametrical Multi-Dimensional Scaling, revealed a strong gradient of change in the structure of assemblages from shallow to deeper water. Assemblages differed also between areas, but depth explained most of the variation. Data indicate that changes have occurred over the study period from 1981 to 1994 and the possible causes of this are discussed. Furthermore, a comparison with the demersal fish assemblages of the continental shelf off Guinea-Bissau was undertaken, based on the five IPIMAR trawl surveys between 1988 and 1995. This comparison revealed that species are similar between these two areas, but there are important differences such as a lower diversity and a different pattern of dominating species in Cape Verde.
Keywords: fish assemblages, multivariate analysis, Africa.
K. A. Stobberup and P. Amorim: Portuguese Fisheries and Sea Research Institute (IPIMAR), Av. Brasilia, 1449–006 Lisbon, Portugal [tel: +351 21 3027119, fax: +351 21 3015948, e-mail: [email protected]]. O. Tariche: National Fisheries Development Institute (INDP), C.P. 132, S. Vicente, Cape Verde [tel: +238 321373, fax: +238 321616, e- mail: [email protected]]
ICES CM 2002/M:24
How important are seamounts for the dispersal of meiofauna?
Gunnar Gad and Horst Kurt Schminke
In the late 60s investigations were initiated to study the influence of a seamount on the hydrography and on the biology of marine organisms, using the Great Meteor Seamount as an example. Continued studies encompass the project “Seamount Ecology” (SEAMEC) and the expedition No. 42 of R/V “Meteor” in 1998 during which meiofauna samples were taken form the plateau of the Great Meteor Seamount. One of the hypotheses to be tested was whether the isolation of the seamount in conjunction with its specific hydrographical situation might have led to a fauna rich in endemic species. It was therefore necessary to identify species from a variety of taxonomic groups in order to get an idea of their distribution and abundance on the plateau as well as in the surrounding deep sea. Study of the Loricifera, Epsilo- and Draconematidae (Nematoda), and Harpacticoida (Copepoda) showed that the Great Meteor Seamount is a “littoral habitat” which despite its isolation by a permanent circular current harbours an astonishingly diverse meiofauna in an otherwise oceanic environment. Meiofauna taxa may employ quite different dispersal strategies in their efforts to reach and colonise the plateau. Seamounts such as the Great Meteor Seamount resemble “islands” for the colonisation by meiofauna or can act as “stepping stones” for large-scale dispersal.
Keywords: meiofauna, dispersal strategies, isolation, zoogeography.
G. Gad and H. K. Schminke: AG Zoosystematik und Morphologie, Fachbereich 7: Biologie, Geo- & Umweltwissenschaften, Carl von Ossietzky Universität Oldenburg, Carl von Ossietzky-Straße 9–11, D-26111 Oldenburg, Germany [tel: +49 (0)441 798 3373 fax: +049 (0)441 798 3162 e-mail: [email protected] oldenburg.de, [email protected]]
ICES CM 2002/M:25
The fauna of Bear Seamount (New England Seamount chain), and the presence of “natural invader” species
J.A. Moore, M. Vecchione, B. B. Collette, and R. Gibbons
Bear Seamount (39o 55΄N 67o 30΄W) is an extinct undersea volcano rising up from the continental slope of Georges Bank. This seamount is the westernmost peak in the New England Seamount (NES) chain. The fauna associated with this seamount was little known until twenty trawl stations were made in late 2000 by the NOAA ship DELAWARE II. That cruise resulted in a faunal list of over 300 species of invertebrates and fishes. A follow-up cruise in July 2002 has added to our knowledge of overall species diversity. Although some of the captured species are still being identified, we present preliminary identifications and results from that latest cruise. One interesting result from the faunal studies, so far, is the recognition that a small percentage of the fauna is represented by “natural invader” species. Most of these species are more typically found in the eastern Atlantic, and are either rare or previously unknown from the western Atlantic. In addition, a few other eastern Atlantic species are also found on the slope of Georges Bank in close proximity to Bear Seamount. These species appear to represent essentially non-anthropogenic invasion, a natural biogeographic process. How these species arrived at or in the vicinity of Bear Seamount is unknown at this time, however, it is possible that the NES chain is acting as a dispersal corridor or “stepping stones” as envisioned by Hubbs in 1959.
Keywords: deep sea, fauna, seamount, North Atlantic, biogeography.
J. A. Moore: Harriet L. Wilkes Honors College, Florida Atlantic University, 5353 Parkside Dr, Jupiter, FL 33458, USA [tel: +1 561 799 8025, fax: +1 561 799 8602, e-mail: [email protected]]. M. Vecchione, B. B. Collette, and R. Gibbons: National Systematics Laboratory, National Marine Fisheries Service, National Museum of Natural History, Washington, DC 20560 USA [tel: + 1 202–357–2550, fax: + 1 202–357–1896, e-mail: [email protected], [email protected], [email protected]]
ICES CM 2002/M:26
Exploratory fishing of the orange roughy (Hoplostethus atlanticus) in some seamounts of the Azores archipelago
Octavio Melo and Gui Manuel Machado Menezes
An exploratory fishing experiment towards the species Hoplostethus atlanticus (orange roughy) was implemented in the Azorean waters during 2001/2002. Orange roughy has been found on several seamounts and pinnacles in the Azores EEZ. A total of 94 different fish species were caught. Among these, more than 20 fish species were recorded for the first time for the Azores archipelago. The catches of molluscs and crustaceans were negligible. The bycatch was less than 4% of the total catch of Orange roughy, being the most important fish species caught, the Aphanopus carbo, Alepocephalus rostratus and the shark Centroscymnus coelolepsis and C. crepidater. The catches of orange roughy (Hoplostethus atlanticus) occur mainly between the 1000 and 1100m of depth and between 5 and 7ºC of bottom temperature. The observed size of orange roughy caught ranged between 13 and 60 cm in standard length, mainly between 44 and 54 cm. The observed ratio between males and females was more or less 1:0.62. The weight of the individuals ranged between 0.14 and 8 kg. The largest specimens, usually females, can reach a standard length of 60 cm and a body weight of 8 kg. The most probable spawning season for this species in the Azores begins in January, since at this time most of the gonads are in a pre-spawning/spawning stages. At this time it was also observed an increase in the size of the orange roughy schools and catch rates, being observed a separation of sexes between geographical schools in the same seamount, before they form bigger schools with both sexes in an intermediate location. The diet of the orange roughy caught in this experiment included small deep-sea fish species, cephalopods and shrimps.
Keywords: exploratory fishery, Hoplostethus atlanticus, seamount, Azores.
O. Melo: Universidade dos Açores, Departamento de Oceanografia e Pescas, Cais de Santa Cruz, 9901–862 Horta, Faial, Portugal [tel: +351 2922 00400, fax: +351 29220 0411] G. M. M. Menezes: University of the Azores (UA), Department of Oceanography and Fisheries (DOP), PT - 9901–862 Horta (Azores) Portugal [tel: +3512 922 92944/292292945/292292988/292293460 fax: +351 292 292 659, e-mail: [email protected]]
ICES CM 2002/M:27
Composition and vertical distribution of zooplankton at the Great Meteor Seamount, subtropical NE Atlantic
Bettina Martin
During an expedition with R. V. Meteor in September 1998 zooplankton was caught at 11 stations over the plateau and on the slope of the Great Meteor Seamount, using a Longhurst Hardy Plankton Recorder [LHPR]. Throughout the hauls sound scattering layers and zooplankton migration were observed with the ship’s 33 kHz echosounder. Abundance, composition and vertical distribution of zooplankton groups at the seamount are described. In addition the abundance of copepod exuvia was determined. A general comparison showed no differences in biomass between the region over the plateau and adjacent deeper waters, although higher biomass and a slightly different composition of zooplankton groups were found at the upstream side of the seamount. Strongly vertically migrating plankton groups like euphausiids and copepods of the genus Pleuromamma were found in high abundances at daytime close to the ground of the plateau. While acoustic observations in the upper 200 m generally correspond with the biomass data of the hauls the deeper sound scattering layers were apparently not caused by the organisms caught with the LHPR. An exception was the daytime station above the ground of the plateau were a distinct scattering layer as well as high net-biomass were found. The abundance of exuvia was higher on versus off the seamount. This can be explained using the ‘Meteor Seamount Model’. The model describes an up to ten times higher retention for passive particles than for vertically migrating ones in the Taylor column over the summit. The uneven distribution of zooplankton in the vicinity of the Great Meteor Seamount is probably caused by both predation of those groups that are trapped by the summit floor at their downward migration at dawn and the flow regime initiated by the irregular bottom topography.
Keywords: zooplankton, Great Meteor seamount, vertical migration, biomass.
B. Martin: Institut für Hydrobiologie und Fischereiwissenschaften, University Hamburg, Olbersweg 24, 22767 Hamburg, Germany [tel: +49 (0)40 428386604, e-mail: [email protected]]
ICES CM 2002/M:28
The role of Zenopsis spp. as predator in seamount and shelf habitats
Heike Zidowitz, Heino O. Fock, and Hein v. Westernhagen
The genus Zenopsis Gill 1862 consists of three species. Zenopsis nebulosus has a wide distribution in the (Indo-)Pacific Ocean whereas Zenopsis conchifer occurs in the Atlantic and Indian Oceans. Zenopsis oblongus, described in 1989, is closely related to Z. nebulosus and known from the Nasca Ridge in the Pacific. Feeding studies are reviewed for all three species. At the Great Meteor seamount (NE Atlantic), Z. conchifer shows a shift in prey selectivity with ontogenetic development. Smaller specimens (< 40 cm SL) preyed on constituents of the deep scattering layer (DSL) (myctophids, stomiids). Lor larger specimens (> 40 cm) diet predominantly consisted of bentho-pelagic Macroramphosus spp., which was the most abundant fish species on that seamount. A similar ontogentic shift was observed for Z. conchifer on the Namibian shelf. However, prey for the larger specimens consisted mainly of the pelagic species Trachurus trachurus and Synagrops microlepis. In the Pacific, Z. oblongus obtains a similar trophic position with regard to migrating components of the DSL. However, though being also very abundant at the Nasca- Ridge seamounts, no Macroramphosus spp. were eaten. Large specimens of Z. nebulosus were found to prey on bentho- pelagic rockfishes (Sebastidae). Zenopsis spp. appears to be an off-bottom pelagic predator with preference for mesopelagic food components in all areas considered. It is suggested that larger specimens abandon the off-bottom pelagic feeding mode and that body size thus determines the capabilities of Zenopsis spp. to prey on bentho-pelagic species.
Keywords: bentho-pelagic fish assemblages, deep scattering layer.
H. Zidowitz, H. O. Fock, and H. v. Westernhagen: Alfred-Wegener-Institute for Polar and Marine Research, PO Box 12 01 61, D-27515 Bremerhaven, Germany [tel: + 49 471 4831 1382, fax: +49 471 4831 1425, e-mail: initial first [email protected]]
ICES CM 2002/M:29 Withdrawn
ICES CM 2002/M:30
The benthic community of the Great Meteor Bank
Nils Benke
During a cruise to the Great Meteor Seamount in 1998 a variety of benthic sampling gear was employed on 48 stations, including a epibenthic sledge, bottom trawl, corers and dredges. From the material only the invertebrates were part of the study, fish have been analysed separately. In total 155 species from 18 taxa have been identified. For 66 of these species it was the first evidence, 19 had already been known, nine of the species are endemic on the Bank. Six species are entirely new to science. The dominating North-East-Atlantic faunal elements (64%), the low number of African elements (30%) and of endemic species (6%) contradict the general perception, that the seamount’s ecology is determined by a faunal community which evolved through isolation. Also the consideration of the life form types show that the bank is not dominated by any special form. Vagile, as well as sessile organisms, filter- feeders, suspension- feeders, carnivores and carrion eaters were found at an approximately equal ratio. This hints at a food supply which does support any kind of specialists. The secondary hard substrates are of special importance from an ecological point of view. 13% of the species were found nearly unexceptionally on secondary hard substrates. The reason for the structure of this faunal community is the location of the Great Meteorbank in the North Atlantic gyre and in the centre of the drain of the Mediterranean water (upper NADW), as well as other islands and seamounts in that region. The water masses transport larvae from the shelf sea either directly, or indirectly over the seamounts and islands to the bank. Only in this way is the manifestation of this North- East Atlantic faunal community understandable.
Keywords: Great Meteor seamount, benthic community, endemic species, faunal elements.
N. Brenke: Fakultät für Biologie, Lehrstuhl für Spezielle Zoologie, Ruhr-Universität Bochum, 44780 Bochum, Germany [tel: +49 234 3225577. e-mail: [email protected]]
ICES CM 2002/M:31
OASIS: a new EU project on the ecology of Atlantic seamounts
Bernd Christiansen
The project OASIS (OceAnic Seamounts: an Integrated Study) aims at describing the functioning characteristics of seamount ecosystems by integrating hydrographic, biogeochemical and biological information. Based on two case studies, OASIS will yield an advanced mechanistic understanding of the processes characterizing seamount ecosystems, and their influence on the surrounding ocean. The scientific results, condensed in a conceptual ecosystem model, will be applied to outline a generic management plan as well as site-specific management plans for the seamounts investigated. The primary goal of OASIS, to provide an holistic, integrated assessment of seamount ecology, will be achieved by addressing the following main objectives: (1) Identifying and describing the physical forcing mechanisms effecting seamount systems (2) Assessing the origin, quality and dynamics of particulate organic material within the water column and surface sediment at seamounts (3) Describing aspects of the biodiversity and the ecology of seamount biota, assessing their dynamics and the maintenance of their production. (4) Modelling the trophic ecology of seamount ecosystems. (5) Application of scientific knowledge to practical conservation.
Keywords: seamount ecosystems, marine conservation, trophic relationships.
B. Christiansen: Universität Hamburg, Institut für Hydrobiologie und Fischereiwissenschaft, Zeiseweg 9, D-22765 Hamburg, Germany [tel: +49 40 42838 6686, fax: +49 40 42838–6696, e-mail [email protected]]
ICES CM 2002/M:32 (Poster)
Prospects of fisheries on the seamounts
V. I. Vinnichenko
Russian fishing experience in different areas of World Ocean indicates significant vulnerability to catching of fish population on the seamounts. Among these species are alfonsino of the Corner Rising seamounts, North Azores area, Walvis and West Indian Ridges; roundnose grenadier of Mid-Atlantic Ridge; mackerel of South Azores and Madeira- Canaries seamounts. Even catches of relatively low quantities (about 0.5–10 thousand tonnes) often led to a lower density and stability of fish concentrations and because of it to a lower yield and productivity of fishing vessels. According to the opinion of some Russian scientists, the majority of fish species on the seamounts form local populations. As a rule, these species do not make long distance migrations and main stages of their life cycle (from fry to sexual mature individuals) proceed in the area of one seamount or a group of narrow situated seamounts. Exchange of genetic material between populations probably occurs only on early life-history stages, which is caused by passive spreading of eggs and larvae by the currents. The results of genetic research and numerous facts of long-time (during some years) absence of fish concentrations on the seamounts after intensive fishing also prove the existence of local populations on the seamounts. Existing data give the ground to consider that the stocks of the majority of fish species are relatively small. Besides, such biological peculiarities of many deepwater fishes inhabiting the seamounts as long lifespan and late sexual maturity make these populations even more vulnerable to fishery. V. I. Vinnichenko: Knipovich Polar Research Institute of Marine Fisheries and Oceanography (PINRO), 6 Knipovich Str., Murmansk, 183763, Russia [tel/fax: +47 789 10 518, e-mail: [email protected]]
ICES CM 2002/M:33 (Poster)
On the pelagic phase of the life cycle of the common angler (Lophius piscatorius Linne) around seamounts of the Rockall-Hatton area
A. G. Arkhipov and N. I. Mylnikov
The system of seamounts Rockall-Hatton is situated to the west of the British Isles (55o–59oN; 14 o17oW). The minimal depths above these underwater heights is some 160–500 m. Ichthyo-fauna is represented approximately by 120 pelagic and bottom fish species belonging to 60 families. The common angler - Lophius piscatorius - is a bottom representative of the thalasso-sublitoral and mesobenthal fauna. It’s larvae and juveniles are pelagic. It was supposed, that upon attaining the length of 8 cm, juveniles descend to the bottom. Our data collected in June-July 2001, showed that juveniles of the common angler occur in the superficial layers in the area 55o20΄-59o 00΄N outside of the exclusive economic zone of Great Britain. The sizes of juveniles varied from 6 to 15 cm. Thus, the transition to the bottom life
style in this species can occur at larger sizes than it was supposed to happen before. This feature promotes dispersal of the species into new habitats (for example, from the shelf to adjacent underwater heights). Besides this, at an early ontogenetic stage Lophius piscatorius possesses a specific adaptation for the pelagic life style. The body of fish is embedded into a jelly cover, reducing body density and assisting juveniles to ‘soar’ into water column. Thus, juveniles of this typical bottom fish have morphological adaptations for a pelagic life, which promote wider dispersion and expansion of its natural habitat.
Keywords: anglerfish, dispersal, juveniles, Rockall.
A. .G. Arkhipov: AtlantNIRO, Kaliningrad, Russia [e-mail: [email protected]]
ICES CM 2002/M:34 (Poster)
Stomach content analysis of dominant copepod species from the Great Meteor Seamount in the Northeast Atlantic
Lutz Fischer
The Great Meteor Seamount in the central south Atlantic rises from a depth of more than 4200 m up to 275 m below the surface. It is characterized by a plateau in the form of a 1465km2 large platform bounded by the 400 m isobath. The aim of the project is an analysis of the effect of the seamount on species composition, individual density and life strategies of the zoo- and ichthyoplankton. The stomach contents of dominant calanoid copepod species were investigated. A multi-closing plankton net was employed both above the mount and in the adjacent open ocean. The overall condition and gut contents of the species caught were investigated using light microscopy. The food organisms were identified, measured and quantified. Histological sections were prepared for analysis of the overall condition of the copepods. Dominant copepods fed mainly on dinoflagellates and diatoms. Silicoflagellates and Radiolaria were rarely found. Larger copepod species such as Mesocalanus tenuicornis, Neocalanus gracilis and N. robustior had, for the most part, full stomachs and were omnivorous. Pieces of copepods were also found in the stomachs. However, using light microscopy, there were rarely any visible content, and if so only very little, in the stomachs of smaller copepods such as Clausocalanus paululus, C. furcatus, Paracalanus denudatus and P. nanus. Histological sections from these species show ingested food, which is no longer identifiable. These results should clarify the hypothesis of the effects of the dominant hydrography on the food spectrum of the abundant calanoid copepods.
Keywords: Great Meteor Seamount, plankton, copepods, feeding-ecology.
L. Fischer: Alfred-Wegener-Institut für Polar- und Meeresforschung, Sektion Vergleichende Ökosystemforschung, Columbusstrasse, 27568 Bremerhaven, Germany [tel: +49 (0)471 48311335, e-mail: [email protected]]
ICES CM 2002/M:35 (Poster)
Occurrence and distribution pattern of copepods in the vicinity of the Great Meteor Seamount, Northeast Atlantic, in September 1998
Sigrid B. Schnack-Schiel and Elke Mizdalski
Zooplankton samples were taken along two transects across the Great Meteor Seamount in September 1998. The main question was whether and if so how strong species composition, abundance and distribution pattern of particular copepods are influenced by the seamount. Stratified sampling included the whole water column above the plateau and slope down to 2500 m at oceanic stations. At all stations the zooplankton population was dominated by copepods representing 80 to 95% of the total numbers. Within the copepods, calanoids contributed the largest fraction followed by poecilostomatoids and cyclopoids. Independent of regions and time of day, copepods occurred in highest abundance in the upper 300 of the water column, showing a distinct day-night difference in vertical distribution. 151 different calanoid species belonging to 64 genera and 24 families were identified. However, only one genus, Clausocalanus, dominated the assemblage at all stations and accounted for between 33 and 51%. Within the adults, five Clausocalanus species could be identified. Calausocalanus furcatus and C. paululus were the most abundant ones. Above the plateau both species contributed a similar fraction while C. paululus was more numerous at the slope and oceanic stations. C. parapergens, C. mastigophorus and C. jobei only occurred in small numbers. All species except C. paululus occurred in higher numbers at the plateau as compared to the surrounding oceanic waters. The maximum abundance of C. furcatus
and C. mastigophorus occurred in the upper 100 m, whereas maxima of C. paululus, C. parapergens and C. jobei were encountered in deeper water layers.
Keywords: Great Meteor Seamount, copepod distribution, calanoid species composition.
S. B. Schnack-Schiel, and E. Mizdalski: Alfred-Wegener-Institut für Polar- und Meeresforschung, Columbusstrasse, D- 27515 Bremerhaven, Germany [e-mail: [email protected]]
ICES CM 2002/M:36 (Poster)
Resource partitioning of deep-sea fishes at the Great Meteor seamount (subtropical NE Atlantic): niche overlap and support for the sound scattering layer-interception hypothesis
Heino O. Fock, Birte Matthiessen, Heike Zidowitz and Hein v. Westernhagen
Inter-species relationships for four fish species of the Great Meteor seamount (subtropical NE Atlantic, 30oN 28.5oW), Macroramphosus spp. Lacépède 1803, Capros aper (L. 1758), Antigonia capros (Lowe 1843) and Zenopsis conchifer (Lowe 1852) were analysed with respect to diet composition, habitat dependent resource utilisation and niche overlap. For all fishes, significant selection of prey in plateau margins of the seamount was found. Unweighted and newly developed weighted overlap indices combining prey composition, habitat use and prey utilisation within habitats revealed high overlap between the boarfishes A. capros and C. aper. The results are in support of the sound scattering layer-interception hypothesis (Isaacs and Schwartzlose 1965), which implies (1) pelagic food utilisation for bentho- pelagic fishes, (2) increased habitat dependent utilisation rate at locations of interception, (3) diurnal changes in utilisation rate due to availability of prey and (4) resource partitioning in order to avoid detrimental levels of competition.
Keywords: bentho-pelagic fish assemblages, North Atlantic.
H. O. Fock, B. Matthiessen, H. Zidowitz, and H. v. Westernhagen: Alfred-Wegener-Institute for Polar and Marine Research, PO Box 12 01 61, D-27515 Bremerhaven, Germany [tel: + 49 471 4831 1382, fax: +49 471 4831 1425, e- mail: initial first [email protected]]
ICES CM 2002/M:37
The upper ocean circulation at Great Meteor Seamount Part II: retention potential of the Seamount induced circulation
Aike Beckmann and Christian Mohn
Implications of the circulation patterns at the Great Meteor Seamount on the marine ecosystem are investigated, utilizing a numerical ocean circulation model. The importance of tidal rectification and internal tide generation has been documented in Part I of this study. In this second part, we use passive tracers to confirm and quantify the idea that there is an area above the seamount, which is largely isolated from the surroundings. Lagrangian particle trajectories are used to test and quantify the potential for retention. We find that passively advected organisms are more likely to remain in the near surface layers above Meteor Seamount than organisms that migrate vertically, who show quite different trajectories and might escape from the area. Finally, the importance of strong wind events on the distribution of particles is illustrated.
Keywords: seamounts, hydrography.
A. Beckmann: Alfred-Wegener Institute for Polar and Marine Research, D-27515 Bremerhaven, Germany [tel: +49 471 4831 1793, fax: +49 471 4831 1797, e-mail: [email protected]]. C. Mohn: Max Planck Institute for Meteorology, Bundesstraße 55, D-20146 Hamburg, Germany [tel: +49 (0)40 41173 431, fax: +49 (0)40 41173 476 e-mail: [email protected]]
ICES CM 2002/M:38 Withdrawn
ICES CM 2002/M:39 (Poster)
Underwater survey of icthyofauna from Eastern Atlantic Seamounts: Gettysburg and Ormond (Gorringe Bank)
Jorge M.S. Gonçales, P. Andrade, J. A.Silva, and J. Bispo
Gettysburg and Ormond are seamounts belonging to the Gorringe bank, which is located on the Europe-Africa plate boundary. These peaks rise from almost 5000 m deep to less than 40 m and extends in a SW-NE direction 125 nm off Cabo de S. Vicente, SW coast of Portugal. Underwater surveys by divers on extreme environments such as these offshore seamounts are very unusual. Given the importance of these oceanic features for understanding marine biodiversity patterns, two surveys were carried out in 1998 (Gettysburg) and 1999 (Ormond) using diving, photography and video for species identification and abundance evaluation. Of the 9 fish species found in Gettysburg and 11 in Ormond, 6 were common to both sites and these included the dominant species: one oceanic and commercially important, Seriola rivoliana, and two coastal typically Atlantic-Mediterranean, Coris julis and Anthias anthias. This result in association with the presence of Abudefduf luridus in Gettysburg, an endemic Macaronesian species, and Thalassoma pavo in both sites, a rare species in Portuguese continental waters, suggests that the upper part of these seamounts may act as “stepping stones” for the dispersal of coastal species.
Keywords: Seamounts, Macaronesia, Gorringe, icthyofauna.
J. M. S. Gonçalves: Universidade do Algarve, CCMAR/FCMA Campus de Gambelas, 8000–117 Faro, Portugal [tel: +351 289 800 900, fax: +351 289 818 353, e-mail: [email protected]]. J. A. Silva and J. Bispo: Atlantic Wildlife Association, Plascampo, S. João da Venda, 8000 Faro, Portugal [tel. +351 289 391526, e-mail: [email protected]]
ICES CM 2002/M:40 (Poster)
Biodiversity of Loricifera from the plateau of the Great Meteor Seamount
Gunnar Gad
To date virtually nothing is known on the zoogeography of species or higher taxa of the meiobenthic Loricifera. Since the discovery of the group in 1983 only 11 species have been recorded worldwide so far. Most of them have been reported from the Atlantic. In total 14 new species of Loricifera were discovered among the highly diverse meiofauna of the plateau of the Great Meteor Seamount. The study revealed that: (1) species of the deep sea do not occur on the plateau and vice versa. (2) larval instars make up 97% of all specimens found, which may have to do with a newly discovered paedogenetic live cycle, (3) all known genera are represented in the material (Nanaloricus, Pliciloricus and Rugiloricus), but all species are new to science, (4) the many species of Rugiloricus are different from their congeners from other localities of the Atlantic. It is discussed whether endemism is favoured by isolation as could be the case in the Great Meteor Seamount.
Keywords: Loricifera, species diversity, zoogeography, meiofauna, endemism, deep sea, Great Meteor Seamount.
G. Gad: AG Zoosystematik und Morphologie, Fachbereich 7: Biologie, Geo- & Umweltwissenschaften, Carl von Ossietzky Universität Oldenburg, Carl von Ossietzky-Straße 9–11, D-26111 Oldenburg, Germany [tel: +049 (0)441 798 3373, fax: +049 (0)441 798 3162 e-mail: [email protected]]
ICES CM 2002/M:41 (Poster)
Espilo- and Draconematidae (Nematoda) from the plateau of the Great Meteor Seamount
Gunnar Gad
Epsilonematidae are a well-defined family within the Nematoda. Like species of the Draconematidae, they have a complex and specialised external morphology, which is related to their mode of locomotion and the substrate they inhabit. At present, there are 91 described species of Epsilonematidae and 80 species of Draconematidae. For most species distribution data are rare, and for many species only the type localities are known. A possible explanation is that most ecological studies on Nematoda only deal with higher-level taxa. In the course of a study of the meiofauna from the plateau of the Great Meteor Seamount 15 samples were examined. The samples yielded 17 species of Epsilonematidae and 15 species of Draconematidae. Most of the species found are new to science. Three species will
placed in new genera, and five genera were recorded for the first time from the Atlantic. For example, a new species of Glochinematinae, Glochinema kentrosaurides, was described from coarse biogenic sands on the plateau of the Great Meteor Seamount at 455 m depth. All other Glochinematinae to date are known only from the Pacific. An overview will be given on the zoogeography and the dispersal potential of these taxa of Nematoda.
Keywords: Nematoda, Epsilonematidae, Draconematidae, zoogeography, Great Meteor.
G. Gad: AG Zoosystematik und Morphologie, Fachbereich 7: Biologie, Geo- & Umweltwissenschaften, Carl von Ossietzky Universität Oldenburg, Carl von Ossietzky-Straße 9–11, D-26111 Oldenburg, Germany [tel: +049 (0)441 798 3373, fax: +049 (0)441 798 3162 e-mail: [email protected]]
ICES CM 2002/M:42 (Poster)
Feeding ecology of Orange Roughy in the Azores Archipelago
Luís Barceloss, Octávio. Melo, Filipe Porteiro, and Gui Menezes
An exploratory fishery of Orange Roughy (Hoplostethus atlanticus, Collett 1889) was done in some seamounts of the Azores Archipelago, Portugal, during spring and autumn (2001) and winter (2002). A sample of 3070 stomachs of this species was analysed. The results showed that 90.36% had empty stomachs and only 9.64% had food: fishes (60.84%), squids (38.78%) and shrimps (20.53%) composed the prey. The analysis of the results suggested that Orange Roughy had a 24-hour feeding period, although feeding increased on the daylight period, especially in the afternoon. In wintertime were found the highest proportion of empty stomachs, coincidentally with the observed spawning season.
Keywords: feeding ecology, Hoplostethus atlanticus, stomach, analysis.
L. Barcelos: Universidade dos Açores, Departamento de Oceanografia e Pescas, Cais de Santa Cruz, 9901–862, Portugal, [tel: +351 292 200 400, fax: +351 292 200 411, e-mail: [email protected] O. Melo: [e-mail: [email protected]]. F. Porteiro: [e-mail: [email protected]]. G. Menezes: [e-mail: [email protected]]