Brill (Colistium guntheri) and turbot (C. nudipinnis) were aged by counting opaque growth zones i... more Brill (Colistium guntheri) and turbot (C. nudipinnis) were aged by counting opaque growth zones in whole and sectioned otoliths. Zones counts from whole otoliths under-estimated age compared with counts from thin otolith sections. Other species of flatfish that have previously been aged from whole otoliths should be re-examined for evidence of age under-estimation, which may be common in species with thick otoliths. Marginal analysis of thin sections supported the hypothesis that one translucent and one opaque zone are formed each year in brill aged 5–10-years old. Marginal analyses for brill greater than 10 years of age, and for turbot, were inconclusive. However, 2+ and 3+ captive-reared turbot deposited the expected number of opaque zones from hatching. Both species grow rapidly for the first three years of life before growth slows appreciably. Turbot grow faster and larger than brill, and females grow faster and larger than males in both species. Growth is minimal in fish older ...
The Dumont d'Urville Sea (East Antarctic region) has been less investigated for DNA barcodin... more The Dumont d'Urville Sea (East Antarctic region) has been less investigated for DNA barcoding and molecular taxonomy than other parts of the Southern Ocean, such as the Ross Sea and the Antarctic Peninsula. The Collaborative East Antarctic MARine Census (CEAMARC) took place in this area during the austral summer of [2007][2008]. The Australian vessel RSV Aurora Australis collected very diverse samples of demersal and benthic organisms. The specimens were sorted centrally, and then distributed to taxonomic experts for molecular and morphological taxonomy and identification, especially barcoding. The COI sequences generated from CEAMARC material provide a sizeable proportion of the Census of Antarctic Marine Life barcodes although the studies are still ongoing, and represent the only source of sequences for a number of species. Barcoding appears to be a valuable method for identification within most groups, despite low divergences and haplotype sharing in a few species, and it is...
Deep Sea Research Part I: Oceanographic Research Papers, 2021
Cephalopods are an important component of Southern Ocean food webs but studies analysing their ha... more 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 the 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 useful 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.
Bioluminescence has often been seen as a spectacular yet uncommon event at sea but considering th... more Bioluminescence has often been seen as a spectacular yet uncommon event at sea but considering the vastness of the deep sea and the occurrence of luminous organisms in this zone, it is now more and more obvious that producing light at depth must play an important role structuring the biggest ecosystem on our planet. Three species of deepwater sharks (Dalatias licha,Etmopterus lucifer, andEtmopterus granulosus) were collected from the Chatham Rise, off New Zealand, and for the first time, we documented their luminescence. Comparison of glowing shark pictures, combined with histological description of light organs and hormonal control analysis, highlight the evolutive conservation of the bioluminescence process within Dalatiidae and Etmopteridae. A special emphasis is placed on the luminescence ofD. licha, the largest known luminous vertebrate. This first experimental study of three luminous shark species from New Zealand provides an insight into the diversity of shark bioluminescence...
The diet of Dissostichus mawsoni captured by bottom longline in the Ross Sea region was examined ... more The diet of Dissostichus mawsoni captured by bottom longline in the Ross Sea region was examined during 2003, 2005 and 2010. The diet of sub-adult toothfish was similar to adult toothfish, comprising mainly benthic fishes and cephalopods. Sub-adult toothfish ate a greater variety of smaller prey than adults, including smaller fish and prawns. Grenadiers (Macrourus spp.) were the most important fish and overall prey species. On the continental slope, icefish (Channichthyidae) and eel cods (Muraenolepididae) were also important fish prey, while Psychroteuthis glacialis was the most important cephalopod prey. On oceanic features, toothfish fed mainly on Macrourus spp. but also fed on Antimora rostrata, cephalopods and the occasional mesopelagic to epipelagic fish. Diet varied significantly with toothfish size and location on northern parts of the Mawson and Iselin banks of the Ross Sea continental slope. There was no significant temporal change in diet composition.
A survey of Antarctic toothfish (Dissostichus mawsoni) was conducted in the northern Ross Sea reg... more A survey of Antarctic toothfish (Dissostichus mawsoni) was conducted in the northern Ross Sea region during the winter of 2016 to document the timing and location of spawning activity, to collect biological information about reproductive status during the spawning season and to look for temporal signals in biological data from D. mawsoni that may indicate a spawning migration of mature toothfish from the continental slope region to the northern Ross Sea region. The 58 day survey showed that spawning of D. mawsoni began on some seamounts by early July. No changes were detected between winter and summer in length, age, sex ratio or condition factor distributions for D. mawsoni in the northern Ross Sea as hypothesized following a spawning migration from the slope to the northern Ross Sea region. These results suggest that the distribution of D. mawsoni in the Ross Sea is mainly accomplished through ontogenetic migration and not annual return spawning migrations.
Brill (Colistium guntheri) and turbot (C. nudipinnis) were aged by counting opaque growth zones i... more Brill (Colistium guntheri) and turbot (C. nudipinnis) were aged by counting opaque growth zones in whole and sectioned otoliths. Zones counts from whole otoliths under-estimated age compared with counts from thin otolith sections. Other species of flatfish that have previously been aged from whole otoliths should be re-examined for evidence of age under-estimation, which may be common in species with thick otoliths. Marginal analysis of thin sections supported the hypothesis that one translucent and one opaque zone are formed each year in brill aged 5–10-years old. Marginal analyses for brill greater than 10 years of age, and for turbot, were inconclusive. However, 2+ and 3+ captive-reared turbot deposited the expected number of opaque zones from hatching. Both species grow rapidly for the first three years of life before growth slows appreciably. Turbot grow faster and larger than brill, and females grow faster and larger than males in both species. Growth is minimal in fish older ...
The Dumont d'Urville Sea (East Antarctic region) has been less investigated for DNA barcodin... more The Dumont d'Urville Sea (East Antarctic region) has been less investigated for DNA barcoding and molecular taxonomy than other parts of the Southern Ocean, such as the Ross Sea and the Antarctic Peninsula. The Collaborative East Antarctic MARine Census (CEAMARC) took place in this area during the austral summer of [2007][2008]. The Australian vessel RSV Aurora Australis collected very diverse samples of demersal and benthic organisms. The specimens were sorted centrally, and then distributed to taxonomic experts for molecular and morphological taxonomy and identification, especially barcoding. The COI sequences generated from CEAMARC material provide a sizeable proportion of the Census of Antarctic Marine Life barcodes although the studies are still ongoing, and represent the only source of sequences for a number of species. Barcoding appears to be a valuable method for identification within most groups, despite low divergences and haplotype sharing in a few species, and it is...
Deep Sea Research Part I: Oceanographic Research Papers, 2021
Cephalopods are an important component of Southern Ocean food webs but studies analysing their ha... more 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 the 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 useful 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.
Bioluminescence has often been seen as a spectacular yet uncommon event at sea but considering th... more Bioluminescence has often been seen as a spectacular yet uncommon event at sea but considering the vastness of the deep sea and the occurrence of luminous organisms in this zone, it is now more and more obvious that producing light at depth must play an important role structuring the biggest ecosystem on our planet. Three species of deepwater sharks (Dalatias licha,Etmopterus lucifer, andEtmopterus granulosus) were collected from the Chatham Rise, off New Zealand, and for the first time, we documented their luminescence. Comparison of glowing shark pictures, combined with histological description of light organs and hormonal control analysis, highlight the evolutive conservation of the bioluminescence process within Dalatiidae and Etmopteridae. A special emphasis is placed on the luminescence ofD. licha, the largest known luminous vertebrate. This first experimental study of three luminous shark species from New Zealand provides an insight into the diversity of shark bioluminescence...
The diet of Dissostichus mawsoni captured by bottom longline in the Ross Sea region was examined ... more The diet of Dissostichus mawsoni captured by bottom longline in the Ross Sea region was examined during 2003, 2005 and 2010. The diet of sub-adult toothfish was similar to adult toothfish, comprising mainly benthic fishes and cephalopods. Sub-adult toothfish ate a greater variety of smaller prey than adults, including smaller fish and prawns. Grenadiers (Macrourus spp.) were the most important fish and overall prey species. On the continental slope, icefish (Channichthyidae) and eel cods (Muraenolepididae) were also important fish prey, while Psychroteuthis glacialis was the most important cephalopod prey. On oceanic features, toothfish fed mainly on Macrourus spp. but also fed on Antimora rostrata, cephalopods and the occasional mesopelagic to epipelagic fish. Diet varied significantly with toothfish size and location on northern parts of the Mawson and Iselin banks of the Ross Sea continental slope. There was no significant temporal change in diet composition.
A survey of Antarctic toothfish (Dissostichus mawsoni) was conducted in the northern Ross Sea reg... more A survey of Antarctic toothfish (Dissostichus mawsoni) was conducted in the northern Ross Sea region during the winter of 2016 to document the timing and location of spawning activity, to collect biological information about reproductive status during the spawning season and to look for temporal signals in biological data from D. mawsoni that may indicate a spawning migration of mature toothfish from the continental slope region to the northern Ross Sea region. The 58 day survey showed that spawning of D. mawsoni began on some seamounts by early July. No changes were detected between winter and summer in length, age, sex ratio or condition factor distributions for D. mawsoni in the northern Ross Sea as hypothesized following a spawning migration from the slope to the northern Ross Sea region. These results suggest that the distribution of D. mawsoni in the Ross Sea is mainly accomplished through ontogenetic migration and not annual return spawning migrations.
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