Distribution Of Cephalopods Research Articles

Cephalopod fauna of the Pacific Southern Ocean using Antarctic toothfish (Dissostichus mawsoni) as biological samplers and fisheries bycatch specimens

Cephalopods are an important component of Southern Ocean food webs but studies analysing their habitat and trophic ecology are scarce. Here, we use the Antarctic toothfish Dissostichus mawsoni as a biological sampler of Southern Ocean's cephalopods in the Ross, Amundsen, and D'Urville Seas. Ten cephalopod taxa were identified in the diet of the Antarctic toothfish, with Pareledone turqueti and Moroteuthopsis longimana being the only species present in all the three studied areas. DNA analysis conducted on squid flesh samples allowed identification of eight and two specimens of Mesonychoteuthis hamiltoni and M. longimana, respectively, proving this technique as a potential tool to improve the knowledge of cephalopods biodiversity and biogeography in the Southern Ocean. Stable isotopes were used to compare the habitat (δ13C) and trophic ecology (δ15N) between two life-stages of the two most abundant squid species (M. longimana and Psychroteuthis glacialis) from the D'Urville Sea (both squid species) and Amundsen Sea (only P. glacialis). Higher δ13C values in M. longimana suggest that this species inhabits waters near the Antarctic Polar Front, with incursions into sub-Antarctic waters, whilst P. glacialis spends its entire life in Antarctic waters. The most recently deposited part of the beak is enriched in 15N suggesting an increase in trophic level during squid growth. These results give us the first insights into the bathyal distribution of cephalopods in the Amundsen and D'Urville Seas, as well as into the ontogenetic changes of two of the most consumed squid species by top predators in this region. Such results are an important step towards improving the biogeography of Antarctic cephalopods, being of utmost importance to understand the biodiversity, food web structure, and functioning of this region.

Modeling the Oceanographic Impacts on the Spatial Distribution of Common Cephalopods During Autumn in the Yellow Sea

The importance of the role of cephalopods in marine ecosystems and commercial fisheries has increased over recent years. There is now evidence that the distribution of cephalopods is expanding latitudinally. Nevertheless, information about the spatial distribution of cephalopods and its implications in the Yellow Sea (YS) is not well known. In an attempt to redress this deficiency we firstly conducted a simple analysis of geospatial patterns in fishing effort in the YS during 2012–2016 to ascertain if changes in fishing intensity (across all species) might be responsible for creating an apparent latitudinal shift in cephalopod distribution. Although fishing intensity increased in the YS over the five-year period, there are no significant differences among years within each latitude, implying that all latitudes respond in a similar way each year. We then used long-term scientific survey data (2000, 2009, 2014, and 2017) of cephalopods (Todarodes pacificus, Loliolus spp, Octopus variabilis, Octopus ocellatus, Sepiola birostrata, and Euprymna spp) collected each October in the YS, combined with oceanographic variables including sea surface temperature (SST) and chlorophyll-a concentration (CHLA), to model relationships to establish habitat suitability indices (HSI) using both an arithmetic mean method (AMM) and a geometric mean method (GMM). Cross-validation, standard deviation and mean squared error of prediction (MSEP) were used to evaluate the performance of the HSI. Abundance index data from surveys of 2018 were overlaid on maps of predicted HSI for the same year to visualize the correspondence of the modelled HSI. Spatio-temporal mapping of oceanographic variables showed that SST and CHLA change dramatically around 34°N, which may relate to the spatial distribution of cephalopods. CHLA is the most important oceanographic variable for most squid and octopus species while SST is the most important for bobtail squid. The MSEP showed that the AMM-based HSI performed better than the GMM-based HSI. Future studies should take weighting of oceanographic variables into account and ideally integrate them into a more holistic model to obtain increased precision in predictions when establishing HSI.

Paralarval and juvenile cephalopods within warm-core eddies in the North Atlantic

Many descriptions of paralarval and juvenile cephalopods are poor. By using DNA barcoding, a global bioidentification system for animals, along with morphological investigation, we can confirm species identifications. We have a better chance of eliminating misidentifications and, therefore, documenting the correct abundance and distribution of cephalopods within an area by combining morphological and molecular evidence. The central objectives of this study are to: (1) compare morphological vs molecular identification of cephalopods and (2) determine the occurrence of cephalopods within the deep scattering layer (DSL) within warm core eddies. The specimens reported here were collected between 2014 and 2016 during three transatlantic cruises from Galway, Ireland to St John's, Newfoundland, with a focus on assemblages in warm-core mesoscale eddies on the western part of the transect. Samples were collected from the DSL at multiple stations across mesoscale eddies. In total, 301 cephalopods belonging to 29 species were collected. Not only does our study increase the knowledge of abundance and diversity of pelagic cephalopods in this area, but it also provides sequences for species for which no comparative sequences were previously available. By examining the match/mismatch between morphological and molecular identifications, we highlight a need for revisions in some taxonomic groupings such as the family Cranchiidae.

Vertical and small-scale horizontal distribution of cephalopods in the Charlie-Gibbs Fracture Zone of the Mid-Atlantic Ridge

In summer 2009, NOAA surveyed the nekton fauna of the fracture zone on the Mid-Atlantic Ridge halfway between Iceland and the Azores as a small-scale follow-up to a previous large-scale Norwegian expedition. Midwater sampling with a Norwegian Krill Trawl resulted in 64 discrete-depth samples from 12 stations at depths from near-surface to 3000 m. Seven additional bottom samples were collected with a large trawl at depths of 2000–3500 m. The expedition collected 416 cephalopods in ca. 19 species in the vicinity of the fracture zone. Over 50 hrs of ROV video from the Norwegian expedition was also viewed to determine diel migratory patterns of the most common species of cephalopod in the region, Gonatus steenstrupi, for comparison with the NOAA trawl data. We found that trawl stations southeast of the Subpolar Front were generally most diverse. Cluster analysis showed that midwater trawls were more similar in species composition than bottom trawls. Unlike in the ROV observations, the small G. steenstrupi from trawl samples did not appear to participate in diel vertical migration, suggesting that trawl-caught juveniles are ecologically distinct from those visible in submersible videos.

Using seabirds to map the distribution of elusive pelagic cephalopod species

The distribution of oceanic cephalopod species is not fully understood but seabirds, which feed on cephalopods and cover vast oceanic areas, might work as samplers and mappers of the occurrence of this elusive group. We tracked 17 wandering albatrosses Diomedea exulans at Bird Island, South Georgia (54° S, 38° W) over the austral winter (breeding period) with GPS-loggers, activity recorders and stomach temperature probes. At logger retrieval, diet composition was accessed via stomach flushings of the tagged individuals. Wandering albatrosses captured circumpolar and rarer oceanic squid in all water masses of the Southern Ocean (i.e. Antarctic, sub-Antarctic and subtropical waters), complementing much of the knowledge about the cephalopod distribution in the Atlantic sector of the Southern Ocean. Some cephalopod species showed a distribution range wider than expected, with oceanic fronts not functioning as ecological barriers as previously thought. This suggests they might be capable of overcoming these frontal regimes and even take advantage of their dynamics as migration pathways

First assessment of biomass and abundance of cephalopods Rossia palpebrosa and Gonatus fabricii in the Barents Sea

Studies on the quantitative distribution of cephalopods in the Arctic are limited, and almost completely absent for the Barents Sea. It is known that the most abundant cephalopods in the Arctic are Rossia palpebrosa and Gonatus fabricii. Their biomass and abundance have been assessed for the first time in the Barents Sea and adjacent waters. The maximum biomass of R. palpebrosa in the Barents Sea was 6.216–6.454 thousand tonnes with an abundance of 521.5 million specimens. Increased densities of biomass were annually registered in the north-eastern parts of the Barents Sea. The maximum biomass of G. fabricii in the Barents Sea was 24.797 thousand tonnes with an abundance of 1.705 billion specimens. The areas with increased density of biomass (higher than 100 kg km−2) and abundance (more than 10,000 specimens km−2) were concentrated in deep-water troughs in the marginal parts of the Barents Sea and in adjacent deep-water areas. The biomass and abundance of R. palpebrosa and G. fabricii in the Barents Sea were much lower than those of major taxa of invertebrates and fish and than those of cephalopods in other parts of the World Ocean. It has been suggested that the importance of cephalopods in the Arctic ecosystems, at least in terms of quantitative distribution, could be somewhat lower than in the Antarctic or the tropics. Despite the impact of ongoing warming of the Arctic on the distribution of cephalopods being described repeatedly already, no impact of the current year's climate on the studied species was found. The only exception was the abundance of R. palpebrosa, which correlated with the current year's climate conditions.

Different abilities to regulate tissue hydration upon osmotic challenge in vitro, in the cephalopods Octopus vulgaris and O. insularis

The spatial distribution of cephalopods is influenced by salinity and temperature. In marine osmoconformers, one reason for different spatial distributions maybe the putative distinct capacity to regulate tissue hydration. Adult Octopus vulgaris (n = 6) and O. insularis (n = 6) were obtained by divers from sites along the southern and northeastern Brazilian coasts, respectively. In the laboratory, octopuses were acclimated to full-strength seawater (salinity 34), for 5–10 days. They were then anesthetized (10 min in 4 °C seawater), a portion of the second right arm was removed, and cut into three portions. Tissues were placed in control isosmotic saline (osmolality 1072 mOsm/kg H2O). Fragments were weighed and transferred to either isosmotic, hyposmotic (50%), or hyperosmotic (150%) salines, and their weight was observed for 120 min. Tissue from both species maintained their hydration/weight following the hyposmotic shock, but differed in their response to the hyperosmotic challenge, where hydration remained unchanged in O. insularis, but was significantly reduced in O. vulgaris. This result could partially explain why O. insularis is more abundant than O. vulgaris throughout the shallow reefs and tide pools in the warmer and salty tropical waters of the northeastern Brazilian coast.

Role of hydro-climatic and demographic processes on the spatio-temporal distribution of cephalopods in the western Mediterranean

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 514:105-118 (2014) - DOI: https://doi.org/10.3354/meps10972 Role of hydro-climatic and demographic processes on the spatio-temporal distribution of cephalopods in the western Mediterranean Patricia Puerta1,*, Manuel Hidalgo1, María González2, Antonio Esteban3, Antoni Quetglas1 1Instituto Español de Oceanografía, Centre Oceanogràfic de les Balears, Moll de Ponent s/n, Apdo. 291, 07015 Palma de Mallorca, Spain 2Instituto Español de Oceanografía, Centro Oceanográfico de Málaga, Puerto Pesquero s/n, 29640 Fuengirola, Málaga, Spain 3Instituto Español de Oceanografía, Centro Oceanográfico de Murcia, Varadero 1, 30740 San Pedro del Pinatar, Murcia, Spain *Corresponding author: patricia.puerta@ba.ieo.es, patrix.puerta@gmail.com ABSTRACT: Fluctuations in marine populations occur both in terms of abundance and distributional ranges, and this has major implications for marine ecology and fisheries management. However, little is known about the variability in, and factors influencing, spatial dynamics in marine groups other than fish. Using time series data from trawl surveys conducted in the western Mediterranean Sea from 1994 to 2012, we analysed the variability in population distribution (latitude, longitude and depth) of 2 cephalopod species with contrasting life histories, viz. the nektobenthic squid Illex coindetii and the benthic octopus Eledone cirrhosa. We investigated the influence of demographic information (population density and mean individual size) together with environmental variables (including chlorophyll a concentration, runoff, precipitation, temperature and climate) to identify the main drivers shaping the cephalopod distributions in 4 shelf regions with contrasting oceanographic and geographic conditions. Marked inter-annual fluctuations were found in the distribution of the 2 species. In general, squid and octopus populations were affected by the same variables, but the effect of each variable depended on the species and study region. Different life strategies resulted in contrasting responses to the environment, with I. coindetii associated with variables contemporary to spring surveys. In contrast, E. cirrhosa was primarily affected by conditions during the previous winter. Vertical distribution was mainly explained by individual body length, while chlorophyll, temperature or local climate proved to be more important for geographical displacements. KEY WORDS: Spatio-temporal distribution · Spatial ecology · Illex coindetii · Eledone cirrhosa · Demography · Hydro-climatic conditions Full text in pdf format Supplementary material PreviousNextCite this article as: Puerta P, Hidalgo M, González M, Esteban A, Quetglas A (2014) Role of hydro-climatic and demographic processes on the spatio-temporal distribution of cephalopods in the western Mediterranean. Mar Ecol Prog Ser 514:105-118. https://doi.org/10.3354/meps10972 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 514. Online publication date: November 06, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.

Changes in distribution and range structure of Arctic cephalopods due to climatic changes of the last decades

The warming of Arctic waters over the last decades has been confirmed by the results of numerous studies. New data on distribution of cephalopods in the Arctic were obtained from the research cruises of PINRO (Russia) and IMR (Norway) during 2006–2011. Teuthowenia megalops and Todaropsis eblanae were found in the Arctic for the first time, at distances of more than 1000 km and 2500 km outside of their ranges, respectively. The demersal species T. eblanae inhabiting the lower shelf and upper continental slope has presumably spread into the Barents Sea by the eastern branch of the Norwegian Current, and further by the southern branch of the North Cape coastal current, as far as the Murman shelf. The bathypelagic species T. megalops is carried to the Arctic evidently by the deep-water warm Atlantic Currents. The new spreading areas of both species are obviously the non-reproductive zones of their ranges. Foraging shoals of Todarodes sagitatus were recorded in the Arctic in 2010 for the first time in the last 25 years, which can be related to not only the warming of Arctic waters, but also the fluctuation of Todarodes levels in the main part of the range in the Northern Atlantic. The native Arctic species Gonatus fabricii has expanded its range to the eastern part of the Barents Sea and to the adjacent part of the Kara Sea. In these areas of Arctic waters, warming is particularly noticeable and the ongoing climatic changes are leading to boreal cephalopods spreading into the Polar Basin. This may impact species relations in vulnerable Arctic ecosystems.

Cephalopod species richness in the wider Caribbean region

The cephalopods of the wider Caribbean region (western central Atlantic) were examined in terms of distribution and ecological importance. In all, 4190 preserved cephalopod specimens were identified and catalogued to produce regional maps of cephalopod distribution within the wider Caribbean. Regional species richness was examined with respect to Rapoport’s rule (RR) and to determine possible cephalopod hotspots in the region. Rarefaction curves were used to normalize the samples of various size collected throughout the wider Caribbean. Cephalopods of the wider Caribbean within latitudinal bands from 8 to 308N do not support RR because they exhibit increasing species richness with increasing latitude. Eight subareas were chosen to compare species richness. Regionally, species richness appears to be patchy, with cephalopods concentrated more off the eastern Florida coast. There is a need for increased sampling throughout the wider Caribbean. Areas were lacking in samples, especially the central and southeastern parts of the region. There is a need to explore the systematics, life histories, and distribution patterns for this group of organisms in future.

CEPHALOPOD DISTRIBUTION IN ISKENDERUN BAY (EASTERN MEDITERRANEAN-TURKEY)

Normal 0 false false false EN-US X-NONE X-NONE/* Style Definitions */ table.MsoNormalTable {mso-style-name:Table Normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri,sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;}This paper is the first comprehensive work on the biology and distribution of cephalopods in the Iskenderun Bay area of Mediterranean Sea. Information on the distribution of Cephalopod fauna was collected through 45 deep-trawl surveys carried out on the commercial trawl fishery waters (between 20 and 200 m) between March 2004 and May 2005. During the study, a total of 1101 individuals belonging to eight species; two cuttlefishes, two squids and four octopods, were recorded. Mean value of dorsal mantle lengths and body weights of the captured species were; 10.74 ± 0.10 cm and 126.42 ±3.24 g for Sepia officinalis, 4.2 cm and 4.68 g for Sepia elegans, 15.3±0.42 cm and 87.68 ±6.35 g for Loligo vulgaris, 10.93 ±0.28 cm and 48.17 ±4.52 g for Illex coindetii, 8.08 ±0.13 cm and 99.17 ±4.01 g for Eledone moschata, 13.5 cm and 281.46 g for Eledone cirrhosa, 10.25±0.45 cm and 370.33 ±53.89 g for Octopus vulgaris, 12.71±0.64 cm and 405.59 ±51.69 g for Octopus macropus. In addition the present study also provides information on dorsal mantle length – body weight relationship and biology of the species found in this particular area.

Distribution of cephalopods in the upper epipelagic northwestern Bering Sea in autumn

In the northwestern Bering Sea in autumn, the epipelagic cephalopod community was represented by the boreal fauna, and was found to be composed of three families and nine species of the order Teuthida: Gonatidae (Berryteuthis magister, Boreoteuthis borealis, Gonatopsis japonicus, Gonatus madokai, Gonatus kamtschaticus, Gonatus onyx, and Gonatus pyros), Chiroteuthidae (Chiroteuthis calyx) and Onychoteuthidae (Onychoteuthis borealijaponica). Two pelagic gonatid species (B. borealis and G. kamtschaticus) dominated the cephalopod community in the upper 50 m. The distribution patterns of B. borealis and G. onyx were associated with diel vertical migrations of these squid. The distribution of two distinct size groups of G. kamtschaticus suggested ontogenetic migration of larger squid to deeper layers, and adds to previous data suggesting that this species may be a heterogeneous assemblage. Demersal B. magister rarely occurred in the surface waters. The occurrence of maturing O. borealijaponica in the southern marine area indicated that these were occasional seasonal migrants from the ocean. The occurrence of juvenile C. calyx suggested that these squid may conduct vertical forage migrations from deep waters to the surface layers.

Diet of Risso's dolphin (<i>Grampus griseus</i>) in the western Mediterranean Sea

The diet of Risso’s dolphin in the Mediterranean is described based on 15 animals stranded between 40°25’N 00°32’W and 37°35’N 00°45’E from April 1987 to January 2003. The prey were mainly oceanic cephalopods. Pelagic octopods, especially A. argo, were the most abundant (mean = 41.28%; SD±34.32). Species belonging to the families Ommastrephidae, Histioteuthidae and Onychoteuthidae were also frequent components of its diet. The bathymetric distribution of cephalopods shows that Risso’s dolphin preferentially feeds on the middle slope (600 to 800 m depth) in the Mediterranean.

COMPOSITION AND DISTRIBUTION OF THE CEPHALOPOD FAUNA IN THE EASTERN ADRIATIC AND EASTERN IONIAN SEA

the composition and spatial distribution of cephalopods in the eastern Adriatic and the eastern Ionian Sea were analyzed based on the samples collected during the trawling campaigns performed in 1996, 1997, 1998, and 2000 in the framework of the MEDItS Project “International bottom trawl Survey in the Mediterranean Sea”. cephalopod samples were collected with a bot- tom trawl net, at sea depths ranging between 21 and 800 meters. A total of 32 species was registered, out of which 26 were found in the northern and central eastern Adriatic, 21 in the south eastern Adriatic region, and 26 in the eastern Ionian area. Results of the multivariate analysis revealed the existence of three main species assemblages related to the depth gradient, with minor differences between regions. Eledone moschata, Loligo vulgaris, and Alloteuthis media had the highest biomass percentage in the assemblage related to the upper continental shelf. the assemblage observed on the middle slope of the south eastern Adriatic was charact...

Cephalopods in the Diet of Swordfish (Xiphias gladius) Caught off the West Coast of Baja California, Mexico

The lower beaks of 1,318 cephalopods from the stomach contents of 175 swordfish, Xiphias gladius, caught off the west coast of Baja California, Mexico, between 1988 and 1996 were analyzed. In total, 20 species of teuthoids, 4 octopods, and one vampyromorph were identified. Weights and lengths of cephalopods were estimated from the lower rostral lengths. Ommastrephid squids, primarily jumbo squid Dosidicus gigas of different maturing sizes, composed 60% by number and 82% by estimated weight. Three species of gonatids were identified and represented 22% by number. An unidentified species of Argonauta was the most abundant octopod, with 5.8% of the beak total. Ancistrocheirus lesueurii is recorded for the first time in the California Current. Distribution of cephalopods in the California Current and their size in the diet of other marine predators are discussed. The diet of swordfish was dominated by medium to large muscular squid species that probably are eaten in surface waters at night.

Cephalopods distribution in the southern Aegean Sea

The present study concerns faunal composition and distribution of cephalopods in the southern Aegean Sea (35Ζ 13’ 19’’- 37Ζ 55’ 25’’ N, 23Ζ 00’ 15’’ - 28Ζ 15’ 37’’ E). Samples were collected from 708 hauls, obtained by an experimental bottom trawl net during eight surveys carried out in the summers of the years 1994-2001, as well as by commercial trawl net during four surveys carried out in September 1995, December 1995, May and September 1996. The hauls were performed at depths ranging from 16 to 778 m. A total of 34 species of cephalopod in 12 families were identified, including 11 oegopsid squid, 3 myopsid squid, 7 octopod, 3 cuttlefish and 10 sepiolid. Trawling with the experimental net resulted in the capturing of some uncommon pelagic species, such as Ctenopteryx siculaand Octopoteuthis sicula, which were recorded for the first time in the Aegean Sea. Most of the species showed a wide depth and geographical range. The species: Sepia officinalis, Sepietta neglecta, Sepietta obscuraand Sepiola rondeletiwere caught only on the continental shelf, whereas the Ancistroteuthis lichtensteini, Bathypolypous sponsalis, Brachioteuthis riisei, Chiroteuthis veranyi, Ctenopteryx sicula, Heteroteuthis dispar, Histioteuthis reversa, Neorossia caroli and Pyroteuthis margaritiferawere found only on the slope. The rest of the species extended in both continental shelf and slope. The spatial distribution of different species groups is discussed in relation to the hydrology and topography of the study area and the species ecology.

Cephalopod assemblages caught by trawling along the Iberian Peninsula mediterranean coast

The cephalopod fauna collected in five MEDITS-ES trawl surveys carried out on the Iberian Mediterranean coast was analysed. Hauls, which were carried out in spring between 1994 and 1998, numbered 480. A total of 34 cephalopod species, grouped in 11 families, was found at depths of between 25 and 786 m. Species and samples assemblages were analysed with the Bray-Curtis similarity index. From the physical parameters studied (depth, temperature and bottom type) only depth showed a positive correlation with cephalopod distribution. Three main cephalopod communities were defined: the shelf community (< 150 m), the middle slope community (> 480 m) and a group of cephalopods which were widely distributed more abundantly on the lower continental shelf-upper slope (150-480 m). SIMPER analysis revealed that Loligo (Alloteuthis) media was the main indicator species of the shelf group, Eledone cirrhosa was the indicator species of the lower shelf upper slope group and Todarodes sagittatus of the middle slope community. The 150-480 m stratum was considered a transitional zone, representing an overlapping region for shelf and slope faunas.

Distribution of cephalopods recorded in the diet of the Patagonian toothfish (Dissostichus eleginoides) around South Georgia

The cephalopod component of the diet of Patagonian toothfish, Dissostichus eleginoides, around South Georgia was analysed from stomach contents collected between March and May 2000. Cephalopods occurred in 7% of D. eleginoides stomachs. A total of 363 cephalopod beaks were found, comprising 16 cephalopod species, of which 15 had not been previously recorded in the diet. Octopodid A (probably Pareledone turqueti) was the most important cephalopod species by number of lower beaks (36 beaks; 20.2% of the lower beaks) and Kondakovia longimana was the most important in terms of estimated mass (76% of the cephalopod component). When the cephalopod component of D. eleginoides was compared with other predators between March and May 2000, D. eleginoides fed more on octopods (25% of the lower beaks) than black-browed and grey-headed albatrosses (<1% of the lower beaks). The low frequency of the squid Martialia hyadesi in the diet of D. eleginoides around South Georgia was also noticed in the diet of albatrosses, and suggests that M. hyadesi was not present in these waters in 2000 (probably due to migratory movements or reproduction failure), despite being a candidate for commercial exploitation. The presence of the squid Mesonychoteuthis hamiltoni in the diet of D. eleginoides and being caught by a longline hook whilst presumably feeding on D. eleginoides, may indicate that juveniles of Mesonychoteuthis hamiltoni are prey of D. eleginoides adults, and when Mesonychoteuthis hamiltoni reach a large size as adults, they become the predator.

Composition and spatial distribution of cephalopods in two north-western Mediterranean areas

The faunistic composition and the spatial distribution of the cephalopod fauna were studied and compared in two areas of the north-western Mediterranean: the Catalan Sea (Spanish coast) and the northern Tyrrhenian Sea (Italian coast). In all, 46 species were collected in the Catalan Sea and 36 in the northern Tyrrhenian Sea. The bathymetric distribution of common species does not differ notably between the two areas. In both, cephalopod abundance is greatest between 50 and 200 m deep. To compare the seasonal changes in bathymetric distribution, four representative species were selected. O. vulgaris is more abundant in both areas between 0 and 50 m in autumn; E. cirrhosa and I. coindetii between 50 and 200 m. Both the last species and S. elegans are more abundant in spring in the Catalan Sea and in autumn in the northern Tyrrhenian Sea. The results of cluster analysis show the presence, in both areas, of three clear associations: one group consists of shallow hauls, another of hauls made over the continental shelf and the third of deeper hauls.

Cephalopods and mesoscale oceanography at the Antarctic Polar Front:satellite tracked predators locate pelagic trophic interactions

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 136:37-50 (1996) - doi:10.3354/meps136037 Cephalopods and mesoscale oceanography at the Antarctic Polar Front: satellite tracked predators locate pelagic trophic interactions Rodhouse PG, Prince PA, Trathan PN, Hatfield EMC, Watkins JL, Bone DG, Murphy EJ, White MG Predator data and exploratory fishing in the Scotia Sea have revealed the presence of cephalopod stocks in the Antarctic Polar Frontal Zone (PFZ). This is a vast, remote region where large epipelagic cephalopods aggregate into highly mobile schools making them difficult to locate and sample. We used satellite tagged predators and shipboard acoustics for coarse and fine scale location of cephalopod concentrations, and sampled them with commercial and scientific nets to determine the relationship between cephalopod distribution and mesoscale oceanographic features at the PFZ. Satellite tags were attached to 9 grey-headed albatrosses Diomedea chrysostoma, breeding at Bird Island, South Georgia, to monitor foraging at sea in January-March 1994. A foraging area at the PFZ, north of South Georgia, was located, an acoustic survey undertaken and a fixed station established where acoustic targets were found. A net survey was carried out with a commercial pelagic trawl, a rectangular midwater trawl 25 m2 (RMT25), a horizontal multiple plankton sampler and a neuston net. Acoustic layers were targeted and the RMT25 sampled 200 m layers to 1000 m in daylight and darkness. Cephalopods were simultaneously recovered from food samples fed to D. chrysostoma chicks at Bird Island. Two CTD transects, approximately normal to the major current flow, were undertaken across the PFZ and remote-sensed sea-surface temperature images from NOAA polar orbiting satellites were obtained aboard ship. The pelagic trawl sampled a cephalopod community that closely resembled that exploited by D. chrysostoma. The largest and most conspicuous species was the ommastrephid squid Martialia hyadesi which is the most important cephalopod prey species. Net-sampled M. hyadesi had been feeding on crustaceans and mesopelagic fish. The cephalopod community was sampled in a feature, interpreted as a warm core ring, in an area characterised by mesoscale features associated with the bathymetry of the northern end of the Northeast Georgia Rise and near a gap in the Falkland Ridge. The association of these mesoscale features with the bathymetry suggests that they may be predictable foraging locations for the cephalopods and their predators. Martialia hyadesi . Acoustic targets . Warm core ring . Grey-headed albatross Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 136. Publication date: June 06, 1996 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1996 Inter-Research.