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Yves Cherel - One of the best experts on this subject based on the ideXlab platform.
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A review on the biodiversity, distribution and trophic role of cephalopods in the Arctic and Antarctic marine ecosystems under a changing ocean
Marine Biology, 2018Co-Authors: José C. Xavier, Yves Cherel, Rui Rosa, Louise Allcock, Rushan M. Sabirov, Martin E. Blicher, Alexey V. GolikovAbstract:Cephalopods play an important role in polar marine ecosystems. In this review, we compare the biodiversity, distribution and trophic role of cephalopods in the Arctic and in the Antarctic. Thirty-two species have been reported from the Arctic, 62 if the Pacific Subarctic is included, with only two species distributed across both these Arctic areas. In comparison, 54 species are known from the Antarctic. These polar regions share 15 families and 13 genera of cephalopods, with the giant squid Architeuthis dux the only species confirmed to occur in both the Arctic and Antarctic. Polar cephalopods prey on crustaceans, fish, and other cephalopods (including cannibalism), whereas predators include fish, other cephalopods, seabirds, seals and whales. In terms of differences between the cephalopod predators in the polar regions, more Antarctic seabird species feed on cephalopods than Arctic seabirds species, whereas more Arctic mammal species feed on cephalopods than Antarctic mammal species. Cephalopods from these regions are likely to be more influenced by climate change than those from the rest of the World: Arctic fauna is more subjected to increasing temperatures per se, with these changes leading to increased species ranges and probably abundance. Antarctic species are likely to be influenced by changes in (1) mesoscale oceanography (2) the position of oceanic fronts (3) sea ice extent, and (4) ocean acidification. Polar cephalopods may have the capacity to adapt to changes in their environment, but more studies are required on taxonomy, distribution, ocean acidification and ecology.
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New records of the giant squid Architeuthis dux in the southern Indian Ocean
2015Co-Authors: Yves CherelAbstract:Only one specimen of Architeuthis dux was previously reported from the southern Indian Ocean. The present work adds ten new records of giant squid in the area. Two remains of fresh specimens have been collected from La Re ¤ union Island (218S) and Amsterdam Island (388S) in tropical and subtropical waters, respectively. Eight other squid were identi¢ed from beaks found in stomach contents of sleeper sharks caught in Kerguelen waters (47 to 488S) located in the southern Polar Frontal Zone. These new data together with published and unpublished information on the food of seabirds and marine mammals indicate that giant squid have a wide distribution throughout the southern Indian Ocean. Most records of the giant squid (Architeuthis dux Steenstrup, 1857) come from some localities in the North Atlantic (Newfoundland, northern Europe), South Atlantic (South Africa), New Zealand and the North Paci¢c (Japan). It is thought to be a cosmopolitan species or a complex of species, but, in many parts of the world ocean, either no or a few specimens have been recorded (Clarke, 1966; Roper & Boss, 1982). In the Indian Ocean, except the occurrence of specimens in the diet of sperm whales caught o ¡ eastern South Africa and western Australia (Clarke, 1980), only one giant squid was found stranded on the small oceanic island of Saint Paul in 1874, the so-called A. sanctipauli Velain, 1875 (Species dubium; Fo « rch, 1998). In this note, we report two new observations of speci-mens at sea and the occurrence of beaks of giant squid in the diet of deep-sea sharks from di¡erent water masses of the southern Indian Ocean. Giant squid were identi¢ed from the morphology of their chitinous lower and upper beaks. Beaks of A. dux have a typical shape, the chitin is thin and lightly coloured, and often the wings and lateral walls curl up (Clarke, 1986). Lower beaks might be confused with those of Thysanoteuthis rhombus Troschel, 1857, but Architeuthis beaks grow to and darken at a larger size (Clarke, 1986). Lower rostrum length (LRL) was measured with a vernier caliper, and dorsal mantle length (ML) was estimated using the allometric equation fro
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Mitochondrial genome diversity and population structure of the giant squid Architeuthis: genetics sheds new light on one of the most enigmatic marine species
Proceedings of the Royal Society B: Biological Sciences, 2013Co-Authors: I. Winkelmann, P. F. Campos, J. Strugnell, L. Allcock, H. Schroeder, Marie-louise Kampmann, Yves Cherel, Tsunemi Kubodera, P J Smith, A. Del GuerraAbstract:Despite its charismatic appeal to both scientists and the general public, remarkably little is known about the giant squid Architeuthis, one of the largest of the invertebrates. Although specimens of Architeuthis are becoming more readily available owing to the advancement of deep-sea fishing techniques, considerable controversy exists with regard to topics as varied as their taxonomy, biology and even behaviour. In this study, we have characterized the mitochondrial genome (mitogenome) diversity of 43 Architeuthis samples collected from across the range of the species, in order to use genetic information to provide new and otherwise difficult to obtain insights into the life of this animal. The results show no detectable phylogenetic structure at the mitochondrial level and, furthermore, that the level of nucleotide diversity is exceptionally low. These observations are consistent with the hypotheses that there is only one global species of giant squid, Architeuthis dux (Steenstrup, 1857), and that it is highly vagile, possibly dispersing through both a drifting paralarval stage and migration of larger individuals. Demographic history analyses of the genetic data suggest that there has been a recent population expansion or selective sweep, which may explain the low level of genetic diversity.
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Top predators and stable isotopes document the cephalopod fauna and its trophic relationships in Kerguelen waters
2011Co-Authors: Yves Cherel, Nicolas Gasco, Guy DuhamelAbstract:Information on the poorly known but ecologically important cephalopod fauna of subantarctic islands was collected using fishery bycatches, together with published data from oceanographic cruises and top predators (fishes and seabirds) as biological samplers. overall, the cephalopod fauna from Kerguelen Islands includes at least 38 different species. oegopsid squids dominate the assemblage over octopods (31 and 6 taxa, respectively), with one species of sepiolid occurring over the shelf. This rich community includes a large diversity of pelagic squids, four benthopelagic cirrate octopods and two endemic benthic octopodids. The results emphasize the importance of ommastrephids, onychoteuthids, cranchiids and a few other squid species in the nutrition of top consumers in the southern ocean. The trophic structure of the community of cephalopods (n = 18 representative species) was subsequently investigated by using the stable isotopic signature of their chitinized beaks. δ13C values demonstrated that cephalopods grew in three different marine ecosystems, with 16 species living and developing in Kerguelen waters and two species migrating from either antarctica (Slosarczykovia circumantarctica lipinski, 2001) or the subtropics (the giant squid Architeuthis dux steenstrup, 1857). Values of δ15N indicate that species living in Kerguelen slope waters encompass almost three distinct trophic levels with a continuum of two levels between crustacean- and fish-eaters, and a distinct higher trophic level occupied by the colossal squid Mesonychoteuthis hamiltoni robson, 1925. The stable isotopic signature of beaks therefore revealed new trophic relationships and migration patterns and is a powerful tool to investigate the role of the poorly known cephalopods in the marine environment.
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Stable isotopes document the trophic structure of a deep-sea cephalopod assemblage including giant octopod and giant squid.
Biology Letters, 2009Co-Authors: Yves Cherel, V. Ridoux, J. Spitz, Patrick RichardAbstract:Although deep-sea cephalopods are key marine organims, their feeding ecology remains essentially unknown. Here, we report for the first time the trophic structure of an assemblage of these animals (19 species) by measuring the isotopic signature of wings of their lower beaks, which accumulated in stomachs of stranded sperm whales. Overall, the species encompassed a narrow range in delta(13)C values (1.7 per thousand), indicating that they lived in closely related and overlapping habitats. delta(13)C values can be interpreted in terms of distribution with the more (13)C-depleted species (e.g. Stigmatoteuthis arcturi, Vampyroteuthis infernalis) having a more pelagic habitat than the more (13)C-enriched, bathyal species (e.g. Todarodes sagittatus and the giant squid Architeuthis dux). The cephalopods sampled had delta(15)N values ranging 4.6 per thousand, which is consistent with the species spanning approximately 1.5 trophic levels. Neither the giant octopod (Haliphron atlanticus) nor the giant squid reached the highest trophic position. Species delta(15)N was independent of body size, with large squids having both the highest (Taningia danae) and lowest (Lepidoteuthis grimaldii) delta(15)N values. Their trophic position indicates that some species share the top of the food web, together with other megacarnivores such as the sperm whale.
Mark A. Hindell - One of the best experts on this subject based on the ideXlab platform.
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the diet of sperm whales physeter macrocephalus in southern australian waters
Ices Journal of Marine Science, 2004Co-Authors: Karen Evans, Mark A. HindellAbstract:Stomach contents were collected from 36 sperm whales (Physeter macrocephalus) involved in two mass stranding events during February 1998 along the west coastline of Tasmania, Australia. Contents were dominated by oceanic cephalopods, with a total of 101 883 cephalopod beaks representing 48 species from 14 families of Teuthids, two species from two families of Octopods, and a single Vampyromorph species identified. Species diversity was higher in these animals than other sperm whales studied in the southern hemisphere, with samples containing an average of (±s.d.) 28.4 ± 11.1 species per sample. Diet samples were dominated by subtropical and muscular cephalopod species. Members of the family Histioteuthidae were the most important numerically, and were also important in terms of estimated reconstituted mass, although members of the Onychoteuthidae were the most dominant species in samples in terms of estimated reconstituted mass. Other families numerically important to species composition included the cranchiid, lepidoteuthid, onychoteuthid, and pholidoteuthid families, while the architeuthid, pholidoteuthid, and ommastrephid families were also important in terms of reconstituted mass. Cephalopod species composition varied with stranding site and with sex, but not with age. However, differences did not represent systemic variation with groups marked by high individual variability. Lower rostral lengths of all cephalopod species ranged from 1.3 to 40.7 mm. Calculated dorsal mantle lengths from all species ranged from 10.7 to 2640.7 mm (mean ± s.d. = 233.7 ± 215.7 mm) and estimated wet weights of cephalopod prey ranged from 2.7 to 110 233.1 g (mean ± s.d. = 828.3 ± 3073.6 g). While there were differences in the size of some cephalopod species between stranding sites and with age, this was marked by high individual variability. Differences in diet composition and prey size between sperm whales reflect individual variability in foraging success and perhaps also foraging groups related to the social structure of this species. © 2004 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.
A. Del Guerra - One of the best experts on this subject based on the ideXlab platform.
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Recent ¢ndings of the giant squid Architeuthis in northern Spanish waters
2016Co-Authors: A. Gonza F. Lez, A. Del Guerra, F. Rocha, J. Gracia, Eduardo CabelloAbstract:There are just a few records of giant squid of the species Architeuthis captured alive. Two living sub-adult females of Architeuthis of 180 and 135 cm mantle length with total weights of 148 and 81kg respectively, were caught 34 miles o¡shore in northern Spanish Atlantic waters (43852.540N^05818.740W) in December 1999 andJanuary 2001. From April 1999 to January 2000 in the same area, another giant squid of 102 kg as well as a single tentacle measuring 5m, and another tentacle of 2m long were caught. Another ¢ve living speci-mens were captured and11more animals were caught dead during the last 15 years in the same area
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What does the giant squid Architeuthis dux eat?
Hydrobiologia, 2014Co-Authors: M. Regueira, P. Belcari, A. Del GuerraAbstract:Architeuthis dux diet has been analysed according to information available from literature and from the analysis of gut contents of five females and two males from Mediterranean and Atlantic Iberian waters (20 specimens in total). This is the first time that A. dux diet from Atlantic and Mediterranean waters is described. Body weight of specimens ranged from 22.5 to 200 kg. In order to infer common patterns in giant squid diet according to its geographic distribution range, size and sex, available data on their diet composition structure were joined and examined with multivariate techniques. No significant differences in the trophic level on which A. dux prey on were found, considering size, sex and location. Thus, A. dux seems to play the same role in the trophic webs throughout the distribution range examined in this paper, which takes up a very wide geographic area. The trophic level estimated from the diet composition is 4.7. Obtained results show that this species preys mainly on pelagic fast swimmers and shoaling fishes and cephalopods as an opportunistic ambushing hunter.
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Mitochondrial genome diversity and population structure of the giant squid Architeuthis: genetics sheds new light on one of the most enigmatic marine species
Proceedings of the Royal Society B: Biological Sciences, 2013Co-Authors: I. Winkelmann, P. F. Campos, J. Strugnell, L. Allcock, H. Schroeder, Marie-louise Kampmann, Yves Cherel, Tsunemi Kubodera, P J Smith, A. Del GuerraAbstract:Despite its charismatic appeal to both scientists and the general public, remarkably little is known about the giant squid Architeuthis, one of the largest of the invertebrates. Although specimens of Architeuthis are becoming more readily available owing to the advancement of deep-sea fishing techniques, considerable controversy exists with regard to topics as varied as their taxonomy, biology and even behaviour. In this study, we have characterized the mitochondrial genome (mitogenome) diversity of 43 Architeuthis samples collected from across the range of the species, in order to use genetic information to provide new and otherwise difficult to obtain insights into the life of this animal. The results show no detectable phylogenetic structure at the mitochondrial level and, furthermore, that the level of nucleotide diversity is exceptionally low. These observations are consistent with the hypotheses that there is only one global species of giant squid, Architeuthis dux (Steenstrup, 1857), and that it is highly vagile, possibly dispersing through both a drifting paralarval stage and migration of larger individuals. Demographic history analyses of the genetic data suggest that there has been a recent population expansion or selective sweep, which may explain the low level of genetic diversity.
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A review of the records of giant squid in the north-eastern Atlantic and severe injuries in Architeuthis dux stranded after acoustic explorations
2004Co-Authors: A. Del Guerra, F. RochaAbstract:A review of the verified reports to date of Architeuthis dux showed that 26% (148 specimens) of worldwide reports were derived from the north-eastern Atlantic. Biological data are presented on fifteen females and two males from Asturian waters (Northern Spain). Both males represent the two first records captured off the Iberian Peninsula. Immature and maturing females ranged from 60 to 140 Kg total weight, whilst mature males weights were 42 and 66 Kg. The peculiar observation of spermatophores embedded in the skin of one of the males near the proximal part of the ventral, ventro-lateral and dorso-lateral arms is discussed. A comparison was undertaken of several morphometric measurements between both sexes and between these two males and five other north-eastern Atlantic males from which data were available. Two incidents of multiple strandings affecting nine specimens in 2001 and 2003 appear to be linked spatially and temporally to geophysical prospecting using air-gun arrays in the Bay of Biscay. Here we present evidence of acute tissue damage in the stranded and surface-floating giant squids. The incidence of such cases during two research cruises contemporary with integrated geological and geophysical studies of the continental margin of the Cantabric Sea indicate that acoustic factors could have caused or contributed to the organ and tissue lesions that probably caused the deaths of these animals. Thus, further environmental regulation of such activity may be warranted to protect animals of the continental slope.
Karen Evans - One of the best experts on this subject based on the ideXlab platform.
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the diet of sperm whales physeter macrocephalus in southern australian waters
Ices Journal of Marine Science, 2004Co-Authors: Karen Evans, Mark A. HindellAbstract:Stomach contents were collected from 36 sperm whales (Physeter macrocephalus) involved in two mass stranding events during February 1998 along the west coastline of Tasmania, Australia. Contents were dominated by oceanic cephalopods, with a total of 101 883 cephalopod beaks representing 48 species from 14 families of Teuthids, two species from two families of Octopods, and a single Vampyromorph species identified. Species diversity was higher in these animals than other sperm whales studied in the southern hemisphere, with samples containing an average of (±s.d.) 28.4 ± 11.1 species per sample. Diet samples were dominated by subtropical and muscular cephalopod species. Members of the family Histioteuthidae were the most important numerically, and were also important in terms of estimated reconstituted mass, although members of the Onychoteuthidae were the most dominant species in samples in terms of estimated reconstituted mass. Other families numerically important to species composition included the cranchiid, lepidoteuthid, onychoteuthid, and pholidoteuthid families, while the architeuthid, pholidoteuthid, and ommastrephid families were also important in terms of reconstituted mass. Cephalopod species composition varied with stranding site and with sex, but not with age. However, differences did not represent systemic variation with groups marked by high individual variability. Lower rostral lengths of all cephalopod species ranged from 1.3 to 40.7 mm. Calculated dorsal mantle lengths from all species ranged from 10.7 to 2640.7 mm (mean ± s.d. = 233.7 ± 215.7 mm) and estimated wet weights of cephalopod prey ranged from 2.7 to 110 233.1 g (mean ± s.d. = 828.3 ± 3073.6 g). While there were differences in the size of some cephalopod species between stranding sites and with age, this was marked by high individual variability. Differences in diet composition and prey size between sperm whales reflect individual variability in foraging success and perhaps also foraging groups related to the social structure of this species. © 2004 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.
Angel Guerra - One of the best experts on this subject based on the ideXlab platform.
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isotope signatures recorded
2014Co-Authors: Angel Guerra, Graham J. Pierce, Ángel F. González, Ro Rodríguez-navarro, C. S. Romanek, Pedro Álvarez-lloret, Vigo SpainAbstract:history traits of the giant squid Architeuthis dux revealed from stabl
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el calamar gigante Architeuthis dux un coloso de las profundidades
2014Co-Authors: Angel GuerraAbstract:Presentacion de la conferencia dictada en el XVI Foro dos Recursos Marinos e da Acuicultura das Rias Galegas, Illa de A Toxa (O Grove), 10 e 11 de outubro de 2013
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The giant squid Architeuthis: An emblematic invertebrate that can represent concern for the conservation of marine biodiversity
Biological Conservation, 2011Co-Authors: Angel Guerra, Ángel F. González, Santiago Pascual, Earl G. DaweAbstract:The current public perception is that there is little reason for concern for the conservation of marine invertebrates, in part due to the scarcity of emblematic species to represent that diverse group. This paper shows that giant squid can be considered an emblematic species to represent concern for the conservation of marine invertebrate biodiversity because it satisfies all the requirements of an emblematic species. It shows that Architeuthis attracts public interest and attention and can serve as an indicator of oceanographic conditions and ocean climate change. It asserts that Architeuthis can represent concerns for vulnerable marine ecosystems associated with submarine canyons and that it belongs to a broad diverse phylogenetic group of organisms associated with these canyons, sharing common concerns with that group with respect to vulnerability and conservation. This study also advocates that the giant squid can serve as an indicator of effects of ecosystem stress resulting from anthropogenic effects including ocean acidification and warming. It is also shown to be vulnerable to such anthropogenic effects as fishing, acoustic seismic exploration and, possibly, pollutants.
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Life-history traits of the giant squid Architeuthis dux revealed from stable isotope signatures recorded in beaks
ICES Journal of Marine Science, 2010Co-Authors: Angel Guerra, Ángel F. González, C. S. Romanek, Pedro Álvarez-lloret, Alejandro B. Rodríguez-navarro, Graham J. PierceAbstract:Carbon and nitrogen isotope profiles constructed from the upper beaks of four giant squid Architeuthis dux from the Bay of Biscay and Namibian waters provided a time-integrated record of their diet. Values of d 15 N ranged from 5.5 to 13.4‰ and of d 13 C from 214.4 to 217.8‰. Nitrogen isotope profiles differed significantly in shape among the four animals analysed, but d 15 N increased along each profile, with lowest values around the rostral tip. The difference between the lowest and the highest d 15 N values was � 5.8‰, slightly less than a two-level difference between the trophic position of small and large A. dux. The increase in d 13 C values was not as pronounced as for the d 15 N profiles, but the changes suggest an ontogenetic shift in diet early in life from smaller prey of relatively low trophic status to larger prey of higher status. Fluctuations in d 13 C values observed near the rostral tip may be associated with a greater intrinsic variability in the carbon isotope composition of relatively small prey, and/or transient migratory behaviour early in life. The relative stability of the d 13 C profiles over the remainder of their lifespan is consistent with the hypothesis that adult giant squid inhabit
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Metal and metalloid concentrations in the giant squid Architeuthis dux from Iberian waters.
Marine environmental research, 2008Co-Authors: Paco Bustamante, Ángel F. González, Francisco Rocha, Pierre Miramand, Angel GuerraAbstract:This study investigated 14 trace elements (Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, V and Zn) in the tissues of the giant squid Architeuthis dux from the Mediterranean and Atlantic Spanish waters. As for other families of cephalopods, the digestive gland and the branchial hearts of Architeuthis showed the highest concentrations of Ag, Cd, Co, Cu, Fe, Ni, Se, V and Zn, highlighting their major role in the bioaccumulation and detoxification processes. With the exception of Hg, the muscles showed relatively low trace element concentrations. Nevertheless, this tissue contained the main proportion of the total As, Cr, Hg, Mn, Ni, and Zn body burden because muscles represent the main proportion of the squid mass. These findings suggest that the metal metabolism is overall the same as other cephalopod families from neritic waters. In females, Zn concentrations increased in the digestive gland with the squid's weight likely reflecting physiological changes during sexual maturation. Comparing the trace element concentrations in the tissues of Architeuthis, higher Ag, Cu, Hg and Zn concentrations in the squid from the Mediterranean reflected different exposure conditions. In comparison to other meso-pelagic squids from the Bay of Biscay, Cd concentrations recorded in the digestive gland suggest that Architeuthis might feed on more contaminated prey or that it displays a longer life span that other cephalopods.