30 de ago de 2013

Molecular characterization of Streptococcus agalactiae in diseased farmed tilapia in China

Publication date: 1 November 2013

Source:Aquaculture, Volumes 412–413

Author(s): Defeng Zhang , Aihua Li , Yujuan Guo , Qianqian Zhang , Xuenian Chen , Xiaoning Gong

A severe outbreak of streptococcosis in cultured tilapia ( Oreochromis niloticus ) caused by Streptococcus agalactiae (Group B streptococcus, GBS) has occurred annually in Southern China during the past years, causing significant economic losses. Little is known about the genetic characteristics of the tilapia S. agalactiae that is prevalent in these areas. A total of 51 GBS isolates from tilapia were collected from 27 farms located in distinct geographic regions. The genetic characteristics of GBS were analyzed by MLST, MLVA, serotyping, and PCR screening of mobile genetic elements, genetic marker, and virulence-related genes. The results showed that all of S. agalactiae tilapia isolates have the genotype, Ia-ST7- bac - bca - fbsA - sip - cfb -IS 1381 -IS 861 -GBSil-ISS ag2 , which suggests a low level of genetic diversity and sharing of a recent and similar origin and a low level of genetic differentiation under similar environment selective pressures. Compared with the control, significant differences were detected between the tilapia strains and the S. agalactiae strains of human and bovine origin. Phage typing successfully differentiated all 51 tilapia GBS isolates into two distinct molecular types (type A and B). Interestingly, the phage type of the tilapia GBS isolates was also observed to shift from type A to type B, with the year 2010 as the turning point. Type B GBS isolates are currently prevalent in tilapia populations in China, and should thus be the target strains to detect and develop prophylactic–therapeutic measures. The genetic data obtained in the present study will be helpful in the determination of the epidemiology of tilapia streptococcosis internationally.





August 30, 2013 at 03:34PM,

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Relative contribution of reproductive investment, thermal stress and Vibrio infection to summer mortality phenomena in Pacific oysters

Publication date: 1 November 2013

Source:Aquaculture, Volumes 412–413

Author(s): Carolin C. Wendling , K. Mathias Wegner

Mass mortalities of Pacific oysters Crassostrea gigas occur regularly when temperatures are high. Elevated temperatures facilitate the proliferation and spread of pathogens and simultaneously impose physiological stress on the host. Additionally, periods of high temperatures coincide with the oyster spawning season. Spawning is energetically costly and can further compromise oyster immunity. Most studies monitoring the underlying factors of oyster summer mortality in the field, point to the involvement of abiotic and biotic factors including low salinities, high temperatures, pollutants, toxic algae blooms, pathogen exposure and physical stress in conjunction with maturation. However, studies addressing more than two factors experimentally are missing thus far. Therefore, we investigated the combination of three main factors including abiotic as well as internal and external biotic stressors by conducting controlled infection experiments on pre-and post-spawning as well as on gravid oysters with opportunistic Vibrio sp. at two different temperatures. Based on mortality rates, infection intensity and cellular immune parameters, we provide experimental evidence that all three factors (i.e. reproductive investment, elevated temperatures and infection with opportunistic Vibrio sp.) act additively to the phenomenon of oyster summer mortality, leaving post-spawning oyster more susceptible to SMS than pre-spawning and gravid oysters. While previous studies found that post-spawning oysters have a lower thermal tolerance and a reduced ability to withstand pathogen infections, our study now allows to separate the relative contribution of different causative agents to oyster summer mortality and pinpoint to infection with pathogenic Vibrio sp. being of highest importance. In addition we can add a mechanistic understanding for the higher losses after spawning during which the phagocytic ability of hemocytes was strongly impeded resulting in insufficient clearance of pathogens.





August 30, 2013 at 03:34PM,

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Marteilia cochillia sp. nov., a new Marteilia species affecting the edible cockle Cerastoderma edule in European waters

Publication date: 1 November 2013

Source:Aquaculture, Volumes 412–413

Author(s): Noèlia Carrasco , P. Mike Hine , Mercè Durfort , Karl B. Andree , Nikolaus Malchus , Beatriz Lacuesta , Mar González , Ana Roque , Chris Rodgers , M. Dolors Furones

Marteilia “type C” was recently identified, by molecular characterization, in the cockle Cerastoderma edule from the Ebro Delta in southern Catalonia (Spain) where it caused high mortalities during the summer of 2008. The present paper provides a transmission electron microscopic morphological description and additional molecular analyses. Specific ultrastructural diagnosis is based in TEM observations of mature stages of the parasite characterized by four secondary cells which subdivide into three “proteic masses”. Each proteic mass contained two spores and thus six spores per secondary cell were suspected. The number of secondary cells and number and nature of spores define the morphological taxobasis to distinguish different members of the Phylum Paramyxea. New sequences included in the phylogenetic analysis place Marteilia “type C” in a well-defined cluster proximal to Marteilia refringens . The new data thus corroborate previous results and lead us to formally describe Marteilia “type C” as a new species, Marteilia cochillia n. sp. affecting bivalves in Europe.





August 30, 2013 at 03:34PM,

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Genetic response to combined family selection for improved mean harvest weight in giant freshwater prawn (Macrobrachium rosenbergii) in Vietnam

Publication date: 1 November 2013

Source:Aquaculture, Volumes 412–413

Author(s): Dinh Hung , Nguyen Thanh Vu , Nguyen Hong Nguyen , Raul W. Ponzoni , David A. Hurwood , Peter B. Mather

We estimated genetic changes in body and carcass weight traits in a giant freshwater prawn (GFP) ( Macrobrachium rosenbergii ) population selected for increased body weight at harvest in Vietnam. The data set consisted of 18,387 individual body and 1730 carcass weight records, as well as full pedigree information collected over four generations. Average selection response (per generation) in body weight at harvest (transformed to square root) estimated as the difference between the Selection line and the Control group was 7.4% calculated from least squares mean (LSMs), 7.0% from estimated breeding values (EBVs) and 4.4% calculated from EBVs between two consecutive generations. Favorable correlated selection responses (estimated from LSMs) were found for other body traits including: total length, cephalothorax length, abdominal length, cephalothorax width, and abdominal width (12.1%, 14.5%, 10.4%, 15.5% and 13.3% over three selection generations, respectively). Data in the second generation of selection showed positive correlated responses for carcass weight traits including: abdominal weight, exoskeleton-off weight, and telson-off weight of 8.8%, 8.6% and 8.8%, respectively. We conclude that body weight at harvest responded well to the application of combined (between and within) family selection and correlated responses in carcass weight traits were favorable.





August 30, 2013 at 03:34PM,

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A second generation genetic linkage map for silver carp (Hypophthalmichehys molitrix) using microsatellite markers

Publication date: 1 November 2013

Source:Aquaculture, Volumes 412–413

Author(s): Wenjie Guo , Jingou Tong , Xiaomu Yu , Chuankun Zhu , Xiu Feng , Beide Fu , Shunping He , Fanzhen Zeng , Xinhua Wang , Haiyang Liu , Lusha Liu

In the study, we constructed a second generation genetic linkage map for silver carp ( Hypophthalmichthys molitrix ) using anonymous and EST-derived microsatellite markers in a mapping panel containing 156 “pseudo BC” progenies from two interspecific crosses between silver carp and bighead carp ( Aristichthys nobilis ). A total of 703 markers were ordered on 24 linkage groups (LGs) which are equal to chromosome numbers of the haploid genome of the species. The consensus map spanned 1561.1 cM covering 93.1% of the silver carp genome with an average resolution of 2.2 cM/locus. Length of LGs ranged from 42.1 cM to 97.8 cM (mean 65.0 cM). Total number of markers on individual LG varied from 13 to 56 (mean 29.3). Estimated total length of the female map (1809.0 cM) was 1.52 times longer than that of the male map (1188.5 cM), and the recombination ratio between sexes (female vs. male) was 2.2, showing markedly higher recombination in the females. Percentage of distorted loci in the male map was obviously higher than that in the female map, and 5 segregation distortion regions were identified in the male linkage groups. This second generation genetic linkage map evidently extends previous genetic maps for silver carp, and provides a basis for such studies as quantitative trait locus mapping, comparative genomics and marker-assisted selection.





August 30, 2013 at 03:34PM,

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Effects of growth hormone transgene expression and triploidy on acute stress indicators in Atlantic salmon (Salmo salar L.)

Publication date: 1 November 2013

Source:Aquaculture, Volumes 412–413

Author(s): Avner Cnaani , Ewen McLean , Eric M. Hallerman

Transgenic Atlantic salmon ( Salmo salar ) expressing an opAFP-csGH transgene exhibit 3–6-fold growth rate acceleration in the first years of life. Transgenics intended for production likely will be triploids for purposes of reproductive confinement. Growth hormone (GH) transgene expression and triploidy may affect physiological traits with bearing on fitness, animal welfare, and aquaculture production. The goal of our study was to determine the responses of juvenile GH-transgenic and triploid Atlantic salmon to stress. Groups of one-year old conventionally bred (termed wild-type), GH-transgenic, and triploid Atlantic salmon were subjected to no stress (control), one-week of fasting, or low dissolved oxygen (1.5–2.0 ppm) in triplicated tanks. Blood samples were taken from anesthetized fish, and nine markers of primary and secondary stress response were quantified. In addition, these stress-response markers were monitored over a time-course of 0, 1, 3, 6, and 24 h after handling and air exposure stress. For fish subject to no stress, parameters measured did not differ among genotypes, except that blood pH was higher and p O 2 and potassium levels lower in wild-type than in triploid or transgenic salmon. Immediately after one week of fasting, transgenic fish exhibited higher levels of sodium and chloride than other genotypes, suggesting osmoregulatory difficulty. Immediately after anoxic challenge, transgenic fish exhibited higher hematocrit, p CO 2 , glucose and sodium levels than other genotypes. In the time-course study, levels of stress-response indicators tended to peak at higher levels in GH-transgenic than in triploid than in wild-type salmon, and to not return to baseline levels through 24 h. Results of the experiments collectively demonstrated that wild-type fish maintained homeostasis more effectively than transgenic or triploid fish, exhibiting smaller changes in all measured stress-response parameters. Poor stress response may affect aquaculture performance of transgenic or triploid Atlantic salmon and hence the aquaculture practices needed for their production and maintenance of welfare, and also may reduce their fitness in the wild.





August 30, 2013 at 03:34PM,

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Different protein to energy ratio diets for gilthead sea bream (Sparus aurata): Effects on digestive and absorptive processes

Publication date: 1 November 2013

Source:Aquaculture, Volumes 412–413

Author(s): I. García-Meilán , J.M. Valentín , R. Fontanillas , M.A. Gallardo

Sea bream juveniles were fed for a 12-week period with 7 isoenergetic diets with different levels of protein (35, 38, 41, 44, 47, 50 and 53%). The diets were formulated by changing simultaneously the levels of lipid (from 27 to 19%) and starch (from 21 to 10%). After the growth period, we studied the digestive enzyme activities at 5 h post-feeding and the nutrient absorption capacity at 24 h post-feeding. A progressive increase in the total protease activity (TPA) was found as the content of diet protein rose (from 35 to 41%) and a diminution of TPA activity was detected in sea bream fed high soybean concentrate content diets (50 and 53% dietary protein). Lipase activity did not change by dietary composition. An up-regulation of α-amylase activity, and d -glucose and l -Ala absorption capacities was found in fish fed with the lowest carbohydrate diets, corresponding to 50 and 53% dietary protein. Moreover, the l -lysine absorption capacity was upregulated in fish fed with low protein diets (35, 38, 41 and 44%). Thus, changes in diet composition can modulate enzymatic activities and nutrient absorption capacity, to improve food use and assure growth performance. In this sense, only sea bream fed with the lowest protein diet (35%) had a significantly lower SGR (< 1), although they had the highest voluntary feed intake. Sea bream fed with P 44 and P 47 diets need the minimal adaptive changes to diet and showed good growth.





August 30, 2013 at 03:34PM,

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Functional characterisation of a Fads2 fatty acyl desaturase with Δ6/Δ8 activity and an Elovl5 with C16, C18 and C20 elongase activity in the anadromous teleost meagre (Argyrosomus regius)

Publication date: 1 November 2013

Source:Aquaculture, Volumes 412–413

Author(s): Óscar Monroig , Douglas R Tocher , Francisco Hontoria , Juan C Navarro

The meagre, Argyrosomus regius , is a carnivorous fish with great potential to diversify finfish aquaculture in the Mediterranean. However, currently nothing is known about their essential fatty acid requirements. Meagres are marine fish but also display anadromous behaviour migrating to river estuaries to spawn, and thus may provide an insight to the influence of diadromy on biosynthetic ability for long-chain polyunsaturated fatty acid (LC-PUFA). Our primary aim was to characterise key cDNAs (fatty acyl desaturases and elongases) of the biosynthetic pathway as a key step to establish the capacity of meagre for LC-PUFA biosynthesis from shorter chain PUFA. The cDNA sequences of a fatty acyl desaturase (Fads) and elongase of very long-chain fatty acids (Elovl) were obtained using PCR-based methodologies, and function of the proteins was investigated by expression of the coding sequences of the putative desaturase and elongase in the yeast Saccharomyces cerevisiae . The tissue distribution of both cDNAs was studied by reverse transcription PCR. Our results demonstrated that meagre possesses at least one fatty acyl desaturase and one elongase involved in the endogenous production of LC-PUFA. The meagre desaturase and elongase were identified as orthologues of Fads2 and Elovl5, respectively. Functionally, the desaturase had dual Δ6/Δ8 activity, whereas the elongase exhibited high elongation efficiency for C 18 and C 20 PUFA with low activity towards C 22 PUFA. However, we also showed that the meagre Elovl5 elongated 16:3n − 3 to 18:3n − 3, the first time that C 16 elongation activity had been demonstrated for a fish elongase. Similar to other marine teleosts, expression of fads2 and elovl5 transcripts was highest in brain. The functions and expression of the meagre Fads2 and Elovl5 proteins suggest that the meagre has a ‘marine type’ LC-PUFA biosynthetic pathway, and that its anadromous behaviour has no major influence.





August 30, 2013 at 03:34PM,

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Effect of tryptophan on growth, intestinal enzyme activities and TOR gene expression in juvenile Jian carp (Cyprinus carpio var. Jian): Studies in vivo and in vitro

Publication date: 1 November 2013

Source:Aquaculture, Volumes 412–413

Author(s): Ling Tang , Lin Feng , Chong-Yan Sun , Gang-Fu Chen , Wei-Dan Jiang , Kai Hu , Yang Liu , Jun Jiang , Shu-Hong Li , Sheng-Yao Kuang , Xiao-Qiu Zhou

This study was conducted both in vivo and in vitro to investigate the effects of tryptophan on growth performance, digestive and absorptive function and protein synthesis of juvenile Jian carp ( Cyprinus carpio var. Jian). 1050 juvenile Jian carp (initial weight 7.73 ± 0.03 g) were fed seven isonitrogenous diets with graded concentrations of tryptophan (1.1, 1.7, 2.5, 3.8, 4.9, 6.0, 6.9 g/kg diet) for 8 weeks. Percent weight gain, feed intake and protein retention value were markedly improved, with increases in dietary tryptophan up to 3.8 g/kg diet. Similar trend was found in glutamate–oxaloacetate transaminase (GOT) and glutamate–pyruvate transaminase (GPT) activities, trypsin, lipase and α-amylase activities, Na+/K+-ATPase, alkaline phosphatase (AKP), γ-glutamyl transpeptidase and creatine kinase activities, and relative expression of eIF4E-binding protein (4E-BP). On the other hand, feed conversion ratio, plasma ammonia concentration and the relative expression of target of rapamycin (TOR) in different tissue showed an opposite pattern. A series of experiments in vitro were then carried out. Compared with the control group, tryptophan supplementation increased 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) OD value, protein content and activity of AKP, GOT, GPT and Na+/K+-ATPase in enterocytes and decreased lactate dehydrogenase activity and ammonia concentration in the culture medium. Protein synthesis rate was 17% higher and relative expression of TOR was 28% lower in tryptophan-supplemented than in control carp enterocytes. In conclusion, our results indicate that tryptophan improved fish growth, digestive and absorptive function as well as protein synthesis, which may be partly related to the TOR signaling pathway.





August 30, 2013 at 03:34PM,

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Effect of lipid composition of diets and environmental temperature on the performance and fatty acid composition of juvenile European abalone (Haliotis tuberculata L. 1758)

Publication date: 1 November 2013

Source:Aquaculture, Volumes 412–413

Author(s): Jorge Hernández , Ana Matus de la Parra , Mariano Lastra , María Teresa Viana

Juvenile abalone Haliotis tuberculata groups hatched in the lab from wild broodstock were fed with diets free of long chain polyunsaturated fatty acids (LC-PUFAs) (restriction diet) but with high amount of molecular precursors like 18:3n-3 and 18:2n-6 from linseed and corn oils compared to a control diet formulated with fish oil. Three different temperatures (12, 16 and 20 °C) were chosen to measure the effect of fatty acid accumulation or synthesis compared to the control diet. After 200 days of experimentation, abalone exhibited different growth between each temperature, whereas no differences were observed between diets. However, a higher fatty acid accumulation was observed in muscle tissue at 12 °C. The relative amount of long chain polyunsaturated fatty acids (LC-PUFAs) in the muscle tissue was similar between those individuals fed with the restriction (LC-PUFA free) and full diets. This was clearly observed within the LC-PUFAs eicosapentaenoic acid (EPA) and docosapentaenoic acid (DPA), but not with docosahexaenoic acid (DHA), suggesting that H. tuberculata is able to synthesize the former FAs from their precursors. This pattern was also observed with arachidonic acid (ARA). In general abalone is able to synthesize and accumulate the necessary fatty acids to sustain growth at a wide range of temperatures and dietary sources, especially at lower temperatures, that could mean that this species is able to cope with a broad range of environmental conditions. However, DHA requirement in the H. tuberculata seems to be much inferior than previously reported, and its biosynthesis is undetectable under the present experimental conditions.





August 30, 2013 at 03:34PM,

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The dietary protein requirement of a new Japanese strain of juvenile Chinese soft shell turtle, Pelodiscus sinensis

Publication date: 1 November 2013

Source:Aquaculture, Volumes 412–413

Author(s): Fan Zhou , Xue-yan Ding , He Feng , Yong-bin Xu , Hui-li Xue , Jian-ren Zhang , Wing-Keong Ng

A feeding trial was conducted to determine the optimum dietary protein requirement of a new Japanese strain of juvenile Chinese soft-shell turtle, Pelodiscus sinensis . Five iso-energetic diets were formulated to contain graded protein levels of 340, 370, 400, 430 or 460 g kg− 1 diet and fed to triplicate groups of turtles (mean initial weight, 3.70 ± 0.05 g) for eight weeks. The turtles were reared in 350-L indoor plastic containers (15 turtles/container) provided with aerated freshwater. For each graded increase of dietary protein up to 430 g kg− 1 diet, growth performance of the soft-shell turtles increased significantly. No further growth increase was observed beyond this dietary protein level. The highest feed efficiency and protein productive value were observed in P. sinensis fed the 430 g protein kg− 1 diet. In general, the apparent digestibility coefficients (ADC) of dry matter, crude protein and gross energy increased significantly with increasing dietary protein levels. No significant differences were observed in the ADC of crude lipid among all experimental groups. Turtle whole-body protein content increased significantly from 15.2% to 16.8% with a corresponding decrease in moisture content (75.5% to 74.2%) when fed increasing dietary protein levels. The lowest concentrations of serum protein and cholesterol were observed in turtles fed 340 or 460 g protein kg− 1 diet. Aspartate transaminase activity in turtles fed 340 g protein kg− 1 diet was significantly higher compared to those fed 400 or 430 g protein kg− 1 diet. Broken-line regression analysis indicated that juvenile P. sinensis (Japanese strain) requires 422.0 g protein kg− 1 diet for optimum growth.





August 30, 2013 at 03:34PM,

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Chapter Four The Reniform Reflecting Superposition Compound Eyes of Nephrops norvegicus Optics, Susceptibility to Light-Induced Damage, Electrophysiology and a Ray Tracing Model

Publication date: 2013

Source:Advances in Marine Biology, Volume 64

Author(s): Edward Gaten , Steve Moss , Magnus L. Johnson

The large reniform eyes of the reptant, tube-dwelling decapod Nephrops norvegicus are described in detail. Optically these reflecting superposition compound eyes are a little unusual in that they are laterally flattened, a feature that may enhance their sensitivity in that region, albeit at the expense of resolution. Electrophysiological and anatomical investigations suggest that the eyes are tuned to appropriate spectral and temporal sensitivities in the long and short term through movement of proximal pigments and possibly rhabdom adaptation. Although exposure to ambient surface light intensities is shown to cause damage to the retinal layer, especially in deeper living animals, there is no evidence yet that demonstrates an impact of eye damage on their survival. It is suggested that experimentation on marine decapods, with sensitive eyes, requires that particular attention is paid to their light environment.





August 30, 2013 at 01:55AM,

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Chapter Five Stress Biology and Immunology in Nephrops norvegicus

Publication date: 2013

Source:Advances in Marine Biology, Volume 64

Author(s): Susanne P. Eriksson , Bodil Hernroth , Susanne P. Baden

The Norway lobster Nephrops norvegicus lives at low-light depths, in muddy substrata of high organic content where water salinities are high and fluctuations in temperature are moderate. In this environment, the lobsters are naturally exposed to a number of potential stressors, many of them as a result of the surficial breakdown of organic material in the sediment. This process (early diagenesis) creates a heterogeneous environment with temporal and spatial fluctuations in a number of compounds such as oxygen, ammonia, metals, and hydrogen sulphide. In addition to this, there are anthropogenically generated stressors, such as human-induced climate change (resulting in elevated temperature and ocean acidification), pollution and fishing. The lobsters are thus exposed to several stressors, which are strongly linked to the habitat in which the animals live. Here, the capacity of Nephrops to deal with these stressors is summarised. Eutrophication-induced hypoxia and subsequent metal remobilisation from the sediment is a well-documented effect found in some wild Nephrops populations. Compared to many other crustacean species, Nephrops is well adapted to tolerate periods of hypoxia, but prolonged or severe hypoxia, beyond their tolerance level, is common in some areas. When the oxygen concentration in the environment decreases, the bioavailability of redox-sensitive metals such as manganese increases. Manganese is an essential metal, which, taken up in excess, has a toxic effect on several internal systems such as chemosensitivity, nerve transmission and immune defence. Since sediment contains high concentrations of metals in comparison to sea water, lobsters may accumulate both essential and non-essential metals. Different metals have different target tissues, though the hepatopancreas, in general, accumulates high concentrations of most metals. The future scenario of increasing anthropogenic influences on Nephrops habitats may have adverse effects on the fitness of the animals.





August 30, 2013 at 01:55AM,

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Chapter Six Reproduction Life Cycle, Larvae and Larviculture

Publication date: 2013

Source:Advances in Marine Biology, Volume 64

Author(s): Adam Powell , Susanne P. Eriksson

Nephrops norvegicus represents a very valuable fishery across Europe, and the species possesses a relatively complex life cycle and reproductive biology across spatial and temporal scales. Insights into embryonic and larval biology, and associated abiotic and biotic factors that influence recruitment, are important since this will affect population and species success. Much of the fishery, and indeed scientific sampling, is reliant on trawling, which is likely to cause direct and indirect stresses on adults and developing embryos. We have collated evidence, including that garnered from laboratory studies, to assess the likely effects on reproduction and population. Using know-how from hatchery operations in similar species such as Homarus sp., we also seek to optimise larviculture that could be commercialised to create a hatchery and thus assist stock remediation. This review chapter is therefore divided into three sections: (1) general N. norvegicus reproductive biology, (2) life cycle and larval biology and (3) a comprehensive review of all rearing attempts for this species to date, including a likely way forward for pilot scale and hence commercial restocking operations.





August 30, 2013 at 01:55AM,

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Chapter Seven Nephrops Fisheries in European Waters

Publication date: 2013

Source:Advances in Marine Biology, Volume 64

Author(s): Anette Ungfors , Ewen Bell , Magnus L. Johnson , Daniel Cowing , Nicola C. Dobson , Ralf Bublitz , Jane Sandell

This review focuses on the Norway lobster ( Nephrops norvegicus ) as a resource, describing how the fishery has developed from the 1960s to the present day to become one of the most economically important fisheries in Europe. In 2010, the total landings were 66,500 tonnes, of which UK fishers landed a significant part (58.1%). The Nephrops fishery is also important for countries such as Ireland (11.7% of the total) and Sweden (1.9%) where it is of regional importance. Some are also taken in the Mediterranean, where Italian, Spanish and Greek fishers together take approximately 7% of the total landing. More than 95% of Nephrops are taken using single- or multi-rig trawlers targeting Nephrops or in mixed species fisheries. In regions such as Western Scotland and the Swedish West Coast, creel fisheries account for up to a quarter of the total landings. Across the range, a small proportion (< 5%) is taken using traps in a fishery characterised by larger sized animals that gain a higher price and have lower discard and by-catches of ground fish with low mortalities. The trawling sector, however, is reducing the by-catches of ground fish with the aid of technical measures, such as square-mesh panels and grids and national systems of incentives. Assessments for Nephrops are operated via the 34 functional units (FUs) regarded as stocks. Changes in management procedures have arisen as a result of the advisory input from underwater TV fishery-independent stock surveys. The total allowable catch does not follow FUs but is agreed upon per management area.





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Contributors to Volume 63

Publication date: 2012

Source:Advances in Marine Biology, Volume 63









August 30, 2013 at 01:55AM,

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Series Contents for Last Fifteen Years*

Publication date: 2012

Source:Advances in Marine Biology, Volume 63









August 30, 2013 at 01:55AM,

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Chapter One Molecular Delineation of Species in the Coral Holobiont

Publication date: 2012

Source:Advances in Marine Biology, Volume 63

Author(s): Michael Stat , Andrew C. Baker , David G. Bourne , Adrienne M.S. Correa , Zac Forsman , Megan J. Huggett , Xavier Pochon , Derek Skillings , Robert J. Toonen , Madeleine J.H. van Oppen , Ruth D. Gates

The coral holobiont is a complex assemblage of organisms spanning a diverse taxonomic range including a cnidarian host, as well as various dinoflagellate, prokaryotic and acellular symbionts. With the accumulating information on the molecular diversity of these groups, binomial species classification and a reassessment of species boundaries for the partners in the coral holobiont is a logical extension of this work and will help enhance the capacity for comparative research among studies. To aid in this endeavour, we review the current literature on species diversity for the three best studied partners of the coral holobiont (coral, Symbiodinium , prokaryotes) and provide suggestions for future work on systematics within these taxa. We advocate for an integrative approach to the delineation of species using both molecular genetics in combination with phenetic characters. We also suggest that an a priori set of criteria be developed for each taxonomic group as no one species concept or accompanying set of guidelines is appropriate for delineating all members of the coral holobiont.





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Chapter Two The Biology and Ecology of Black Corals (Cnidaria: Anthozoa: Hexacorallia: Antipatharia)

Publication date: 2012

Source:Advances in Marine Biology, Volume 63

Author(s): Daniel Wagner , Daniel G. Luck , Robert J. Toonen

Antipatharians, commonly known as black corals, are treasured by many cultures for medicinal purposes and to produce jewellery. Despite their economic and cultural importance, very little is known about the basic biology and ecology of black corals because most species inhabit deeper-water environments (> 50 m) which are logistically challenging to study. There has been a recent increase of studies focusing on antipatharians; however, these have not yet been comprehensively reviewed. This literature review seeks to summarize the available information on the biology and ecology of antipatharians. Although black corals occur throughout all oceans and from subtidal to abyssal depths, they are particularly common in tropical and subtropical regions at depths below 50 m. Antipatharians are generally found in areas with hard substrates, low-light and strong currents. Under favourable conditions, some black coral species form dense aggregations to the point of becoming ecologically dominant. Zooplankton appears to be the major component of the diet of black corals, which feed as suspension feeders and use mucus and nematocysts to capture their prey. Previously categorized as azooxanthellate corals, recent research has revealed that many antipatharians appear capable of harbouring symbionts, but unlike other corals, dinoflagellates of the genus Symbiodinium are generally not important to the nutrition of black corals. Antipatharians reproduce through both sexual and asexual processes. In general, polyps and colonies are gonochoric, with fertilization and larval development likely occurring externally; however, to date antipatharian larvae have only been observed for a single species. Antipatharians are generally slow-growing and long-lived organisms with maximum longevities ranging from decades to millennia. Black corals are more abundant with depth, a pattern which has been hypothesized to avoid competition with obligate photosynthetic fauna. Additionally, antipatharians may compete for space by using sweeper tentacles and secondary metabolites. With the exception of a few predators such as gastropods and green sea turtles, antipatharians appear to be little impacted by predation. Like other corals, antipatharians can be habitat engineers of importance to a myriad of associated organisms including arthropods, annelids, echinoderms, mollusks, sponges and cnidarians, several of which are adapted to live exclusively on black corals. Given that most black coral species inhabit remote environments, our understanding of these organisms will depend on our ability to effectively sample and study them. Future collections, particularly in deeper waters (> 50 m), will be needed to determine whether antipatharian species have limited biogeographical distributions or whether this has simply been an artefact of low sampling efforts away from population centres and taxonomic uncertainties within this group. Additionally, biological and ecological studies require increased sample sizes because most information is currently derived from the examination of only a handful of specimens.





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Chapter Three Jellyfish Life Histories: Role of Polyps in Forming and Maintaining Scyphomedusa Populations

Publication date: 2012

Source:Advances in Marine Biology, Volume 63

Author(s): Cathy H. Lucas , William M. Graham , Chad Widmer

Large population fluctuations of jellyfish occur over a variety of temporal scales, from weekly to seasonal, inter-annual and even decadal, with some regions of the world reported to be experiencing persistent seasonal bloom events. Recent jellyfish research has focussed on understanding the causes and consequences of these population changes, with the vast majority of studies considering the effect of changing environmental variables only on the pelagic medusa. But many of the bloom-forming species are members of the Scyphozoa with complex metagenic life cycles consisting of a sexually reproducing pelagic medusa and asexually reproducing benthic polyp. Recruitment success during the juvenile (planula, polyp and ephyrae) stages of the life cycle can have a major effect on the abundance of the adult (medusa) population, but until very recently, little was known about the ecology of the polyp or scyphistoma phase of the scyphozoan life cycle. The aim of this review is to synthesise the current state of knowledge of polyp ecology by examining (1) the recruitment and metamorphosis of planulae larvae into polyps, (2) survival and longevity of polyps, (3) expansion of polyp populations via asexual propagation and (4) strobilation and recruitment of ephyrae (juvenile medusae). Where possible, comparisons are made with the life histories of other bentho-pelagic marine invertebrates so that further inferences can be made. Differences between tropical and temperate species are highlighted and related to climate change, and populations of the same species (in particular Aurelia aurita ) inhabiting different habitats within its geographic range are compared. The roles that polyps play in ensuring the long-term survival of jellyfish populations as well as in the formation of bloom populations are considered, and recommendations for future research are presented.





August 30, 2013 at 01:55AM,

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Chapter Four Hearing in Cetaceans: From Natural History to Experimental Biology

Publication date: 2012

Source:Advances in Marine Biology, Volume 63

Author(s): T. Aran Mooney , Maya Yamato , Brian K. Branstetter

Sound is a primary sensory cue for most marine mammals, and this is especially true for cetaceans. To passively and actively acquire information about their environment, cetaceans have some of the most derived ears of all mammals, capable of sophisticated, sensitive hearing and auditory processing. These capabilities have developed for survival in an underwater world where sound travels five times faster than in air, and where light is quickly attenuated and often limited at depth, at night, and in murky waters. Cetacean auditory evolution has capitalized on the ubiquity of sound cues and the efficiency of underwater acoustic communication. The sense of hearing is central to cetacean sensory ecology, enabling vital behaviours such as locating prey, detecting predators, identifying conspecifics, and navigating. Increasing levels of anthropogenic ocean noise appears to influence many of these activities. Here, we describe the historical progress of investigations on cetacean hearing, with a particular focus on odontocetes and recent advancements. While this broad topic has been studied for several centuries, new technologies in the past two decades have been leveraged to improve our understanding of a wide range of taxa, including some of the most elusive species. This chapter addresses topics including how sounds are received, what sounds are detected, hearing mechanisms for complex acoustic scenes, recent anatomical and physiological studies, the potential impacts of noise, and mysticete hearing. We conclude by identifying emerging research topics and areas which require greater focus.





August 30, 2013 at 01:55AM,

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Contributors to Volume 62

Publication date: 2012

Source:Advances in Marine Biology, Volume 62









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Preface

Publication date: 2012

Source:Advances in Marine Biology, Volume 62

Author(s): Mikel A. Becerro , Maria J. Uriz , Manuel Maldonado , Xavier Turon







August 30, 2013 at 01:55AM,

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Chapter one The Physiology and Molecular Biology of Sponge Tissues

Publication date: 2012

Source:Advances in Marine Biology, Volume 62

Author(s): Sally P. Leys , April Hill

Sponges have become the focus of studies on molecular evolution and the evolution of animal body plans due to their ancient branching point in the metazoan lineage. Whereas our former understanding of sponge function was largely based on a morphological perspective, the recent availability of the first full genome of a sponge ( Amphimedon queenslandica ), and of the transcriptomes of other sponges, provides a new way of understanding sponges by their molecular components. This wealth of genetic information not only confirms some long-held ideas about sponge form and function but also poses new puzzles. For example, the Amphimedon sponge genome tells us that sponges possess a repertoire of genes involved in control of cell proliferation and in regulation of development. In vitro expression studies with genes involved in stem cell maintenance confirm that archaeocytes are the main stem cell population and are able to differentiate into many cell types in the sponge including pinacocytes and choanocytes. Therefore, the diverse roles of archaeocytes imply differential gene expression within a single cell ontogenetically, and gene expression is likely also different in different species; but what triggers cells to enter one pathway and not another and how each archaeocyte cell type can be identified based on this gene knowledge are new challenges. Whereas molecular data provide a powerful new tool for interpreting sponge form and function, because sponges are suspension feeders, their body plan and physiology are very much dependent on their physical environment, and in particular on flow. Therefore, in order to integrate new knowledge of molecular data into a better understanding the sponge body plan, it is important to use an organismal approach. In this chapter, we give an account of sponge body organization as it relates to the physiology of the sponge in light of new molecular data. We focus, in particular, on the structure of sponge tissues and review descriptive as well as experimental work on choanocyte morphology and function. Special attention is given to pinacocyte epithelia, cell junctions, and the molecules present in sponge epithelia. Studies describing the role of the pinacoderm in sensing, coordination, and secretion are reviewed. A wealth of recent work describes gene presence and expression patterns in sponge tissues during development, and we review this in the context of the previous descriptions of sponge morphology and physiology. A final section addresses recent findings of genes involved in the immune response. This review is far from exhaustive but intends rather to revisit for non-specialists key aspects of sponge morphology and physiology in light of new molecular data as a means to better understand and interpret sponge form and function today.





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Chapter two Sponge–Microbe Symbioses Recent Advances and New Directions

Publication date: 2012

Source:Advances in Marine Biology, Volume 62

Author(s): Robert W. Thacker , Christopher J. Freeman

Sponges can host abundant and diverse communities of symbiotic microorganisms. In this chapter, we review recent work in the area of sponge–microbe symbioses, focusing on (1) the diversity of these associations, (2) host specificity, (3) modes of symbiont transmission, and (4) the positive and negative impacts of symbionts on their hosts. Over the past 4 years, numerous studies have catalogued the diversity of sponge–microbe symbioses, challenging previous hypotheses of a uniform, vertically transmitted microbial community and supporting a mixed model of symbiont community transmission. We emphasize the need for experimental manipulations of sponge–symbiont interactions coupled with advanced laboratory techniques to determine the identity of metabolically active microbial symbionts, to investigate the physiological processes underlying these interactions, and to elucidate whether symbionts act as mutualists, commensals, or parasites. The amazing diversity of these complex associations continues to offer critical insights into the evolution of symbiosis and the impacts of symbiotic microbes on nutrient cycling and other ecosystem functions.





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Large-scale occupancy surveys in East Antarctica discover new Adélie penguin breeding sites and reveal an expanding breeding distribution






Research Articles

Colin Southwell, Louise Emmerson,

Antarctic Science, Volume 25 Issue 04, pp 531-535



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Three-dimensional use of marine habitats by juvenile emperor penguins Aptenodytes forsteri during post-natal dispersal






Research Articles

Jean-Baptiste Thiebot, Amélie Lescroël, Christophe Barbraud, Charles-André Bost,

Antarctic Science, Volume 25 Issue 04, pp 536-544



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Persistent organic pollutants in bird, fish and invertebrate samples from King George Island, Antarctica






Research Articles

Caio V.Z. Cipro, Fernanda I. Colabuono, Satie Taniguchi, Rosalinda Carmela Montone,

Antarctic Science, Volume 25 Issue 04, pp 545-552



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Management of Antarctic Specially Protected Areas: permitting, visitation and information exchange practices






Research Articles

L.R. Pertierra, K.A. Hughes,

Antarctic Science, Volume 25 Issue 04, pp 553-564



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Organic-walled microfossils from the north-west Weddell Sea, Antarctica: records from surface sediments after the collapse of the Larsen-A and Prince Gustav Channel ice shelves






Research Articles

Anna J. Pieńkowski, Fabienne Marret, James D. Scourse, David N. Thomas,

Antarctic Science, Volume 25 Issue 04, pp 565-574



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Distribution of depth to ice-cemented soils in the high-elevation Quartermain Mountains, McMurdo Dry Valleys, Antarctica






Research Articles

Margarita M. Marinova, Christopher P. Mckay, Wayne H. Pollard, Jennifer L. Heldmann, Alfonso F. Davila, Dale T. Andersen, W. Andrew Jackson, Denis Lacelle, Gale Paulsen, Kris Zacny,

Antarctic Science, Volume 25 Issue 04, pp 575-582



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SNOW-WEB: a new technology for Antarctic meteorological monitoring






Research Articles

J.H.J. Coggins, A.J. Mcdonald, G. Plank, M. Pannell, B. Jolly, S. Parsons, T. Delany,

Antarctic Science, Volume 25 Issue 04, pp 583-599



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ANS volume 25 issue 4 Cover and Front matter

ANS volume 25 issue 4 Cover and Back matter