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Christopher D. Jones - One of the best experts on this subject based on the ideXlab platform.
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Life history strategies of the Scotia Sea icefish, Chaenocephalus aceratus, along the Southern Scotia Ridge
Polar Biology, 2015Co-Authors: Emilio Riginella, Christopher D. Jones, Carlotta Mazzoldi, Julian R. Ashford, Christina Morgan, Mario La MesaAbstract:Reproductive capacity can influence distribution and abundance over large spatial scales through larval dispersal, even when adult stages remain isolated following settlement. We examined size distribution, reproductive traits and age structure in Scotia Sea icefish, Chaenocephalus aceratus, an abundant benthic species with a long larval pelagic phase found on continental shelves along the Southern Scotia Ridge. In particular, we compared life history strategies between fish caught during surveys undertaken off the South Orkney Islands (SOI) and South Shetland Islands (SSI). Results corroborated regional separation after settlement and suggested distinct life history strategies, in which fish from SOI invested much less in reproduction, and somewhat more in somatic growth earlier in their life history. Compared to SSI, body weight increased faster with length and absolute fecundity was 46 % lower and increased more slowly with size for SOI population. In addition, the proportion of spawning cohorts and L ∞ was lower and k higher for SOI. The differences appeared to be a phenotypic response to environmental conditions related to regional hydrography. Lower reproductive capacity around the SOI, and strong eastward flow in the large-scale circulation, suggests that the SSI may be more important in influencing distributions and abundance of icefish along the Southern Scotia Ridge.
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Interannual variability in the feeding of ice fish (Notothenioidei, Channichthyidae) in the southern Scotia Arc and the Antarctic Peninsula region (CCAMLR Subareas 48.1 and 48.2)
Polar Biology, 2013Co-Authors: Karl-hermann Kock, Joachim Gröger, Christopher D. JonesAbstract:We have studied the annual variation in food intake of three sub-Antarctic ice fish species ( Champsocephalus gunnari , Chaenocephalus aceratus , and Pseudochaenichthys georgianus ) and three high-Antarctic ice fish species ( Chionodraco rastrospinosus , Cryodraco antarcticus , and Chaenodraco wilsoni ). Stomach content analyses were conducted during bottom trawl surveys around the South Shetland Islands in 1998, 2001, 2002, 2003, and 2007, the South Orkney Islands in 1999 and 2009, and off the north-western Antarctic Peninsula in 2002, 2006, and 2006/2007 in order to obtain further insight into the amount of food of Antarctic demersal fish consume during summer. Annual variation in food intake was comparatively low within an area in the krill-feeding species C. gunnari and C. wilsoni . Food intake was much more variable, by a factor of 2 or 3 among years and areas, in larger C. aceratus and C. antarcticus , which rely heavily on fish as their dietary source. Food consumption was intermediate in the two species P. georgianus and C. rastrospinosus , which rely on both krill and fish.
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Nesting behavior of the icefish Chaenocephalus aceratus at Bouvetøya Island, Southern Ocean
Polar Biology, 2005Co-Authors: H. William. Detrich, Christopher D. Jones, Stacy Kim, Anthony W. North, Andrew Thurber, Marino VacchiAbstract:We describe in situ observations on nesting by the Scotia Sea (or blackfin) icefish Chaenocephalus aceratus (Lönnberg) that constitute the first substantive evidence of egg brooding and parental care by species of the family Channichthyidae. At Boutetoya Island six fish, all apparently male, were observed guarding egg nests at depths of 141–148 m during an ROV deployment. Eggs were laid as aggregated, round masses (~20–25 cm diameter) in shallow, circular depressions (~1-m diameter, ~20-cm depth) that were probably excavated by the parent(s) to protect the nests. The fish guardians remained tenaciously in contact with the eggs despite disturbances caused by the ROV, reacting to this threat with stress and defense behaviors. Because brooding fishes are more susceptible to the population impacts from trawl fisheries, we argue that this life history should be kept in mind in designing management schemes.
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Diet of two icefish species from the South Shetland Islands and Elephant Island, Champsocephalus gunnari and Chaenocephalus aceratus
Polar Biology, 2004Co-Authors: Hauke Flores, Karl-hermann Kock, S. Wilhelms, Christopher D. JonesAbstract:The summer diet of two species of icefishes (Channichthyidae) from the South Shetland Islands and Elephant Island, Champsocephalus gunnari and Chaenocephalus aceratus, was investigated from 2001 to 2003. Champsocephalus gunnari fed almost exclusively on krill (Euphausia superba) in all years. The importance of other taxa (Themisto gaudichaudii, mysids, myctophids) in the diet was negligible. The average feeding rate of Champsocephalus gunnari inferred from an exponential gastric evacuation model was between 1.0 and 1.5% body weight per day. Most of the stomachs of Chaenocephalus aceratus were empty. Stomachs with food contained mainly krill, mysids and fish. Among the fish taken, locally abundant species formed the bulk of the diet: Gobionotothen gibberifrons in 2001, Lepidonotothen larseni and Champsocephalus gunnari in 2002 and L. larseni in 2003. An ontogenetic shift in feeding preference of Chaenocephalus aceratus was observed: fish smaller than 30 cm fed on krill and mysids, while larger animals relied primarily on fish.
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The biology of the icefish Cryodraco antarcticus Dollo, 1900 (Pisces, Channichthyidae) in the southern Scotia Arc (Antarctica)
Polar Biology, 2002Co-Authors: Karl-hermann Kock, Christopher D. JonesAbstract:The icefish Cryodraco antarcticus is common in deeper waters of the southern Scotia Arc and the high-Antarctic zone. A number of biological features of this species are presented, with new information collected from recent scientific surveys of the South Shetland Islands and South Orkney Islands. The species is closely related to Chaenocephalus aceratus, but can be distinguished by a number of meristic characters. The two species are similar in size, colouration and body shape, and have a number of aspects of their life-cycle in common, such as reproduction, length-weight relationship and diet. These two species appear to occupy a very similar niche in the southern Scotia Arc ecosystem. However, Cryodraco antarcticus is less abundant and uses different spatial components of shelf areas, replacing Chaenocephalus aceratus in deeper water and high-Antarctic regions.
Mario La Mesa - One of the best experts on this subject based on the ideXlab platform.
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Life history strategies of the Scotia Sea icefish, Chaenocephalus aceratus, along the Southern Scotia Ridge
Polar Biology, 2015Co-Authors: Emilio Riginella, Christopher D. Jones, Carlotta Mazzoldi, Julian R. Ashford, Christina Morgan, Mario La MesaAbstract:Reproductive capacity can influence distribution and abundance over large spatial scales through larval dispersal, even when adult stages remain isolated following settlement. We examined size distribution, reproductive traits and age structure in Scotia Sea icefish, Chaenocephalus aceratus, an abundant benthic species with a long larval pelagic phase found on continental shelves along the Southern Scotia Ridge. In particular, we compared life history strategies between fish caught during surveys undertaken off the South Orkney Islands (SOI) and South Shetland Islands (SSI). Results corroborated regional separation after settlement and suggested distinct life history strategies, in which fish from SOI invested much less in reproduction, and somewhat more in somatic growth earlier in their life history. Compared to SSI, body weight increased faster with length and absolute fecundity was 46 % lower and increased more slowly with size for SOI population. In addition, the proportion of spawning cohorts and L ∞ was lower and k higher for SOI. The differences appeared to be a phenotypic response to environmental conditions related to regional hydrography. Lower reproductive capacity around the SOI, and strong eastward flow in the large-scale circulation, suggests that the SSI may be more important in influencing distributions and abundance of icefish along the Southern Scotia Ridge.
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Age and early life history of juvenile scotia sea icefish, Chaenocephalus aceratus, from Elephant and the South Shetland Islands
Polar Biology, 2007Co-Authors: Mario La Mesa, Julian R. AshfordAbstract:The otolith microstructure of juvenile Scotia Sea icefish (Chaenocephalus aceratus) was analyzed from samples collected around Elephant and South Shetland Islands, with the aim to validate previous annual ageing and to give new insight into its early life history timings. Fish were caught by bottom trawl fishing conducted on the continental shelf between 100 and 500 m depth. To determine the timing and position of the first annulus on sagittal otoliths, microincrements were counted on juvenile otoliths previously aged 1+ year old by counting annuli in sectioned otolith. Assuming that microincrements were laid down daily, age ranged from 406 to 578 days in fish measuring 13–19 cm TL, thus corroborating previous results. The relationship between fish size and otolith size/weight was estimated using the least square linear regression method. The relationship between age and otolith size was also estimated to determine the otolith length in 1-year old fish, which was approximately 1.58 mm. In all samples the otolith core was characterized by an evident strong check, assumed to be laid down at the beginning of exogenous feeding of yolk sac larvae. The yolk sac duration estimated from hatch to the first feeding check was longer than other channichthyids, lasting 29–45 days. Hatching dates were backcalculated from the date of capture using the age estimates, indicating C. aceratus sampled off Elephant and South Shetland Islands hatched over a long period lasting from July to December, with a peak in November. As a result, the potential larval dispersion driven by local oceanographic features is discussed.
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Microsatellite analysis reveals genetic differentiation between year-classes in the icefish Chaenocephalus aceratus at South Shetlands and Elephant Island
Polar Biology, 2007Co-Authors: Chiara Papetti, Karl-hermann Kock, Emanuele Susana, Tomaso Patarnello, Mario La Mesa, Lorenzo ZaneAbstract:Chaenocephalus aceratus is one of the most abundant Antarctic icefish species in the Atlantic sector and has been a by-catch species in the fishery for mackerel icefish, Champsocephalus gunnari, between the mid-1970s and mid-1980s at South Georgia, South Orkney, and South Shetland Islands. The species became the target of the fishery in particular seasons, such as at South Georgia in 1977/78. In our paper, we report results on genetic differentiation for 11 microsatellite loci in C. aceratus samples collected at the South Shetlands and Elephant Island. This study represents the first report on microsatellite variability of an icefish species. Our results support the evidence from previous studies on differences in infestation patterns of parasites that a single panmictic population of C. aceratus exists, spanning the two sampling sites separated by about 100 km. Moreover, our study indicates the presence of a significant genetic differentiation between individual year-classes pointing out the existence of dynamic processes acting at the population genetic level, according to recent results for broadly distributed marine species. Both small effective population size and immigration from unsampled differentiated stocks may be at the base of the differentiation found in C. aceratus.
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Age and growth of Scotia Sea icefish, Chaenocephalus aceratus, from the South Shetland Islands
Antarctic Science, 2004Co-Authors: Mario La Mesa, Julian R. Ashford, E. Larson, M. VacchiAbstract:Samples of Chaenocephalus aceratus (Lonnberg) were collected during a trawl survey carried out around the South Shetland Islands in January–February 2002. Fish were caught by commercial bottom trawl fishing down to 500 m depth, using a stratified randomized sampling design. As observed in other recent surveys within the same area, C. aceratus represented one of the predominant species. Overall, 357 specimens ranging from 13 and 67 cm (TL) were selected for the present study. Ages were estimated by counting annuli present in the sagittal otoliths, exposed by grinding and polishing along their sagittal plane. To estimate the precision of age data, we compared blind readings by readers from different institutions. The age range was 1–17 years for females and 1–15 years for males. Von Bertalanffy growth curves were fitted to the estimated age-length data for each sex. The estimated values of asymptotic length L ∞ (cm) and K (year −1 ) were respectively 79.8 and 0.07 for females and 60.0 and 0.09 for males. The growth performance index ranged between 2 and 2.5, similar to that reported in other icefish. Sexual maturity was attained by females and males at about 10 and 9 years old respectively, at about 60% of their maximum estimated age. These results are compared with age and growth data available in the literature for C. aceratus , and discussed in the light of recent commercial exploitation.
Bruce D. Sidell - One of the best experts on this subject based on the ideXlab platform.
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Thermal Tolerance of Antarctic Notothenioid Fishes Correlates with Level of Circulating Hemoglobin
Physiological and Biochemical Zoology, 2011Co-Authors: Jody M. Beers, Bruce D. SidellAbstract:AbstractThe West Antarctic Peninsula region is experiencing some of the most rapid elevations in temperature of any marine environment. We assessed thermal tolerance of white- and red-blooded Antarctic notothenioid fishes inhabiting these waters, using a modified critical thermal maximum (CTmax) design. Temperature was elevated acutely from ambient at a constant rate of 3.6°C h−1, and CTmax was defined as the temperature where animals lost righting response. CTmax temperatures of white-blooded icefishes Chionodraco rastrospinosus (C) and Chaenocephalus aceratus (C) were significantly lower than those of red-blooded fishes Gobionotothen gibberifrons (C) and Notothenia coriiceps (C). Lepidonotothen squamifrons, a red-blooded species with low hematocrit, exhibited a CTmax (C) that was significantly lower than that of the other red-blooded animals and similar to that of icefishes. A strong relationship between CTmax and hematocrit () suggests that the oxygen-carrying capacity of blood may partially dictate ac...
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morphological and physiological study of the cardiac nos no system in the antarctic hb mb icefish Chaenocephalus aceratus and in the red blooded trematomus bernacchii
Nitric Oxide, 2009Co-Authors: Filippo Garofalo, Bruce D. Sidell, Bruno Tota, Daniela Amelio, Maria Carmela Cerra, Daniela PellegrinoAbstract:Abstract The nitric oxide synthase (NOS)/nitric oxide (NO) system integrates cellular biochemical machinery and energetics. In heart microenvironment, dynamic NO behaviour depends upon the presence of superoxide anions, haemoglobin (Hb), and myoglobin (Mb), being hemoproteins are major players disarming NO bioactivity. The Antarctic icefish, which lack Hb and, in some species, also cardiac Mb, represent a unique model for exploring Hb and Mb impact on NOS/NO function. We report in the (Hb−/Mb−) icefish Chaenocephalus aceratus the presence of cardiac NOSs activity (NADPH-diaphorase) and endothelial NOS (eNOS)/inducible NOS (iNOS) zonal immuno-localization in the myocardium. eNOS is localized on endocardium and, to a lesser extent, in myocardiocytes, while iNOS is localized exclusively in myocardiocytes. Confronting eNOS and iNOS expression in Trematomus bernacchii (Hb+/Mb+), C. hamatus (Hb−/Mb+) and C. aceratus (Hb−/Mb−) is evident a lower expression in the Mb-less icefish. NO signaling was analyzed using isolated working heart preparations. In T. bernacchii, l -arginine and exogenous (SIN-1) NO donor dose-dependently decreased stroke volume, indicating decreased inotropism. l -arginine-induced inotropism was NOSs-dependent, being abolished by NOSs-inhibitor NG-monomethyl- l -arginine ( l -NMMA). A SIN-1-induced negative inotropism was found in presence of SOD. NOS inhibition by l -N5-N-iminoethyl- l -ornithine ( l -NIO) and l -NMMA confirmed the NO-mediated negative inotropic influence on cardiac performance. In contrast, in C. aceratus, l -arginine elicited a positive inotropism. SIN-1 induced a negative inotropism, which disappeared in presence of SOD, indicating peroxynitrite involvement. Cardiac performance was unaffected by l -NIO and l -NIL. NO signaling acted via a cGMP-independent mechanism. This high conservation degree of NOS localization pattern and signaling highlights its importance for cardiac biology.
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Morphological and physiological study of the cardiac NOS/NO system in the Antarctic (Hb-/Mb-) icefish Chaenocephalus aceratus and in the red-blooded Trematomus bernacchii.
Nitric Oxide, 2009Co-Authors: Filippo Garofalo, Bruce D. Sidell, Bruno Tota, Daniela Amelio, Maria Carmela Cerra, Daniela PellegrinoAbstract:Abstract The nitric oxide synthase (NOS)/nitric oxide (NO) system integrates cellular biochemical machinery and energetics. In heart microenvironment, dynamic NO behaviour depends upon the presence of superoxide anions, haemoglobin (Hb), and myoglobin (Mb), being hemoproteins are major players disarming NO bioactivity. The Antarctic icefish, which lack Hb and, in some species, also cardiac Mb, represent a unique model for exploring Hb and Mb impact on NOS/NO function. We report in the (Hb−/Mb−) icefish Chaenocephalus aceratus the presence of cardiac NOSs activity (NADPH-diaphorase) and endothelial NOS (eNOS)/inducible NOS (iNOS) zonal immuno-localization in the myocardium. eNOS is localized on endocardium and, to a lesser extent, in myocardiocytes, while iNOS is localized exclusively in myocardiocytes. Confronting eNOS and iNOS expression in Trematomus bernacchii (Hb+/Mb+), C. hamatus (Hb−/Mb+) and C. aceratus (Hb−/Mb−) is evident a lower expression in the Mb-less icefish. NO signaling was analyzed using isolated working heart preparations. In T. bernacchii, l -arginine and exogenous (SIN-1) NO donor dose-dependently decreased stroke volume, indicating decreased inotropism. l -arginine-induced inotropism was NOSs-dependent, being abolished by NOSs-inhibitor NG-monomethyl- l -arginine ( l -NMMA). A SIN-1-induced negative inotropism was found in presence of SOD. NOS inhibition by l -N5-N-iminoethyl- l -ornithine ( l -NIO) and l -NMMA confirmed the NO-mediated negative inotropic influence on cardiac performance. In contrast, in C. aceratus, l -arginine elicited a positive inotropism. SIN-1 induced a negative inotropism, which disappeared in presence of SOD, indicating peroxynitrite involvement. Cardiac performance was unaffected by l -NIO and l -NIL. NO signaling acted via a cGMP-independent mechanism. This high conservation degree of NOS localization pattern and signaling highlights its importance for cardiac biology.
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Isolation, characterization and nucleotide sequence of the muscle isoforms of creatine kinase from the Antarctic teleost Chaenocephalus aceratus.
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 2003Co-Authors: Paul Winnard, Bruce D. Sidell, Robert E. Cashon, Michael E. VaydaAbstract:Abstract Creatine kinase (CK) was isolated from the white muscle of the Antarctic icefish Chaenocephalus aceratus , which is deficient in glycolytic capacity. C. aceratus white myotomal creatine kinase (MMCK) displayed an apparent K m at 0.5 °C of 0.06 mM for ADP and 17 mM for Phosphocreatine. These K m values are similar to those reported for other vertebrate MMCKs at their physiologically relevant body temperatures. C. aceratus MMCK exhibited optimal activity at pH of 7.6–7.7 at 0.5 °C, in contrast to rabbit MMCK which had optimum activity at pH 6.2 at 30 °C. The apparent V max of C. aceratus MMCK at 0.5 °C is 94±4 S.D. ( n =9) μmol ATP/min/mg (i.e. U/mg), which is comparable to rabbit MMCK assayed at 20 °C and 8-fold greater than rabbit MMCK measured at 0.5 °C. DEAE chromatography of C. aceratus white muscle CK resolved two distinct activity peaks. Cloning and sequencing of C. aceratus CK cDNAs confirmed that two muscle-specific isoforms of CK were expressed that were distinct from the mitochondrial and brain isoforms. Icefish MMCK was sensitive to transient temperature elevation, and the DEAE-fractionated forms were highly unstable. These results indicate that C. aceratus MMCK displays significant activity at physiological temperature and intracellular pH of icefish muscle that could contribute to sustaining energy charge during burst-swimming.
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The myoglobin gene of the Antarctic icefish, Chaenocephalus aceratus, contains a duplicated TATAAAA sequence that interferes with transcription
Journal of Experimental Biology, 2003Co-Authors: Deena Small, Michael E. Vayda, Thomas J. Moylan, Bruce D. SidellAbstract:SUMMARY Six of the 16 known species of Antarctic icefish (family Channichthyidae) have lost the ability to express cardiac myoglobin (Mb) via at least four independent events during radiation of these species. We report here that the lesion in Chaenocephalus aceratus Mb is a duplicated TATAAAA element that blocks transcription. This lesion is distinct from those of other icefish species that do not express cardiac Mb. The C. aceratus Mb gene is nearly identical to that of Chionodraco rastrospinosus , a closely related Mb-expressing icefish species, with one exception. A 15-bp segment is present in C. aceratus but absent from C. rastrospinosus ; this insertion is located 648 bp upstream from the reference transcription start site of C. rastrospinosus and includes the sequence TATAAAA, which bound HeLa cell transcription factor IID (TFIID) and icefish nuclear proteins in gel-retardation assays. Reporter constructs containing the `full-length9 C. aceratus Mb promoter were not expressed in transient expression assays in oxidative skeletal muscle of live icefish. By contrast, constructs employing the nearly identical `full-length9 C. rastrospinosus Mb promoter were efficiently expressed in parallel assays in the same tissue. Truncated constructs of C. aceratus Mb that did not contain the 15-bp duplication were expressed at very low levels. These data confirm a third independent mechanism of Mb loss among channichthyid species, indicate that C. aceratus aerobic muscle is capable of expressing functional Mb genes and demonstrate that duplication of the muscle-specific TATAAAA sequence in an inappropriate context can result in loss of a gene9s expression, resulting in significant physiological consequences.
Julian R. Ashford - One of the best experts on this subject based on the ideXlab platform.
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Life history strategies of the Scotia Sea icefish, Chaenocephalus aceratus, along the Southern Scotia Ridge
Polar Biology, 2015Co-Authors: Emilio Riginella, Christopher D. Jones, Carlotta Mazzoldi, Julian R. Ashford, Christina Morgan, Mario La MesaAbstract:Reproductive capacity can influence distribution and abundance over large spatial scales through larval dispersal, even when adult stages remain isolated following settlement. We examined size distribution, reproductive traits and age structure in Scotia Sea icefish, Chaenocephalus aceratus, an abundant benthic species with a long larval pelagic phase found on continental shelves along the Southern Scotia Ridge. In particular, we compared life history strategies between fish caught during surveys undertaken off the South Orkney Islands (SOI) and South Shetland Islands (SSI). Results corroborated regional separation after settlement and suggested distinct life history strategies, in which fish from SOI invested much less in reproduction, and somewhat more in somatic growth earlier in their life history. Compared to SSI, body weight increased faster with length and absolute fecundity was 46 % lower and increased more slowly with size for SOI population. In addition, the proportion of spawning cohorts and L ∞ was lower and k higher for SOI. The differences appeared to be a phenotypic response to environmental conditions related to regional hydrography. Lower reproductive capacity around the SOI, and strong eastward flow in the large-scale circulation, suggests that the SSI may be more important in influencing distributions and abundance of icefish along the Southern Scotia Ridge.
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Age and early life history of juvenile scotia sea icefish, Chaenocephalus aceratus, from Elephant and the South Shetland Islands
Polar Biology, 2007Co-Authors: Mario La Mesa, Julian R. AshfordAbstract:The otolith microstructure of juvenile Scotia Sea icefish (Chaenocephalus aceratus) was analyzed from samples collected around Elephant and South Shetland Islands, with the aim to validate previous annual ageing and to give new insight into its early life history timings. Fish were caught by bottom trawl fishing conducted on the continental shelf between 100 and 500 m depth. To determine the timing and position of the first annulus on sagittal otoliths, microincrements were counted on juvenile otoliths previously aged 1+ year old by counting annuli in sectioned otolith. Assuming that microincrements were laid down daily, age ranged from 406 to 578 days in fish measuring 13–19 cm TL, thus corroborating previous results. The relationship between fish size and otolith size/weight was estimated using the least square linear regression method. The relationship between age and otolith size was also estimated to determine the otolith length in 1-year old fish, which was approximately 1.58 mm. In all samples the otolith core was characterized by an evident strong check, assumed to be laid down at the beginning of exogenous feeding of yolk sac larvae. The yolk sac duration estimated from hatch to the first feeding check was longer than other channichthyids, lasting 29–45 days. Hatching dates were backcalculated from the date of capture using the age estimates, indicating C. aceratus sampled off Elephant and South Shetland Islands hatched over a long period lasting from July to December, with a peak in November. As a result, the potential larval dispersion driven by local oceanographic features is discussed.
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Age and growth of Scotia Sea icefish, Chaenocephalus aceratus, from the South Shetland Islands
Antarctic Science, 2004Co-Authors: Mario La Mesa, Julian R. Ashford, E. Larson, M. VacchiAbstract:Samples of Chaenocephalus aceratus (Lonnberg) were collected during a trawl survey carried out around the South Shetland Islands in January–February 2002. Fish were caught by commercial bottom trawl fishing down to 500 m depth, using a stratified randomized sampling design. As observed in other recent surveys within the same area, C. aceratus represented one of the predominant species. Overall, 357 specimens ranging from 13 and 67 cm (TL) were selected for the present study. Ages were estimated by counting annuli present in the sagittal otoliths, exposed by grinding and polishing along their sagittal plane. To estimate the precision of age data, we compared blind readings by readers from different institutions. The age range was 1–17 years for females and 1–15 years for males. Von Bertalanffy growth curves were fitted to the estimated age-length data for each sex. The estimated values of asymptotic length L ∞ (cm) and K (year −1 ) were respectively 79.8 and 0.07 for females and 60.0 and 0.09 for males. The growth performance index ranged between 2 and 2.5, similar to that reported in other icefish. Sexual maturity was attained by females and males at about 10 and 9 years old respectively, at about 60% of their maximum estimated age. These results are compared with age and growth data available in the literature for C. aceratus , and discussed in the light of recent commercial exploitation.
Lorenzo Zane - One of the best experts on this subject based on the ideXlab platform.
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Spatial and temporal boundaries to gene flow between Chaenocephalus aceratus populations at South Orkney and South Shetlands
Marine Ecology Progress Series, 2009Co-Authors: Chiara Papetti, Emanuele Susana, Tomaso Patarnello, Lorenzo ZaneAbstract:ABSTRACT: The black-fin icefish Chaenocephalus aceratus is among the most abundant fish specieson the Antarctic continental shelves of the Scotia Arc, and Bouvet Island. We genotyped 11 micro-satellite loci in C. aceratus population samples from South Orkney, southern South Shetlands, andElephant Island (northern South Shetlands) collected in 2002 and 2006. This investigation furtherdevelops a previous study on the species reporting the presence of one panmittic population in south-ern South Shetlands and Elephant Island, with genetic differentiation between year classes. Ourresults reveal a more complex pattern of differentiation than shown previously, as genetic differencesoccur both at the temporal level at Elephant Island and at the geographic scale between southernSouth Shetland–Elephant Islands and South Orkney population samples. In particular, the mag-nitude of genetic differentiation at the temporal scale, the relatively high effective population size( N e ) and high gene flow indicate that genetic differentiation is not only driven by geographic dis-tance. At present, our results should be taken into account when defining conservation measures andmanagement boundaries in regions where fishery is still open or where other Antarctic fish speciesare still exploited.KEY WORDS:
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Microsatellite analysis reveals genetic differentiation between year-classes in the icefish Chaenocephalus aceratus at South Shetlands and Elephant Island
Polar Biology, 2007Co-Authors: Chiara Papetti, Karl-hermann Kock, Emanuele Susana, Tomaso Patarnello, Mario La Mesa, Lorenzo ZaneAbstract:Chaenocephalus aceratus is one of the most abundant Antarctic icefish species in the Atlantic sector and has been a by-catch species in the fishery for mackerel icefish, Champsocephalus gunnari, between the mid-1970s and mid-1980s at South Georgia, South Orkney, and South Shetland Islands. The species became the target of the fishery in particular seasons, such as at South Georgia in 1977/78. In our paper, we report results on genetic differentiation for 11 microsatellite loci in C. aceratus samples collected at the South Shetlands and Elephant Island. This study represents the first report on microsatellite variability of an icefish species. Our results support the evidence from previous studies on differences in infestation patterns of parasites that a single panmictic population of C. aceratus exists, spanning the two sampling sites separated by about 100 km. Moreover, our study indicates the presence of a significant genetic differentiation between individual year-classes pointing out the existence of dynamic processes acting at the population genetic level, according to recent results for broadly distributed marine species. Both small effective population size and immigration from unsampled differentiated stocks may be at the base of the differentiation found in C. aceratus.
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Isolation and characterization of eight microsatellite loci in the icefish Chaenocephalus aceratus (Perciformes, Notothenioidei, Channichthyidae)
Molecular Ecology Notes, 2007Co-Authors: Emanuele Susana, Chiara Papetti, Federica Barbisan, Erica Bortolotto, Simona Buccoli, Tomaso Patarnello, Lorenzo ZaneAbstract:We characterized eight polymorphic microsatellites in the Scotia icefish Chaenocephalus aceratus (Perciformes, Notothenioidei, Channichthyidae) that is endemic of Southern Ocean waters surrounding the tip of the Antarctic Peninsula. Microsatellites were isolated from a partial genomic library enriched for an AC motif. The number of alleles ranged from two to 19 with a mean observed hererozygosity of 0.71. Loci were in Hardy–Weinberg equilibrium and no evidence for linkage disequilibrium was found. These molecular markers will be useful to investigate Scotia icefish genetic structure, possibly providing insights on its effective population size and demographic history.