Fishes

Microsatellite markers were used to investigate the reproductive behavior of the damselfish Abudefduf sordidus at Johnston Atoll, Central Pacific Ocean. Genetic results indicated that ten males maintained guardianship over their nest territories for up to nine nest cycles during a 3.5 month period. Genotypes of 1025 offspring sampled from 68 nests (composed of 129 clutches) were consistent with 95% of the offspring being sired by the guardian male. Offspring lacking paternal alleles at two or more loci were found in 19 clutches, indicating that reproductive parasitism and subsequent alloparental care occurred. Reconstructed maternal genotypes allowed the identification of a minimum of 74 different females that spawned with these ten territorial males. Males were polygynous, mating with multiple females within and between cycles. Genetic data from nests, which consisted of up to four clutches during a reproductive cycle, indicated that each clutch usually had only one maternal contri...

Viral haemorrhagic septicaemia virus (VHSV) has, in recent decades, been isolated from an increasing number of free-living marine fish species. So far, it has been isolated from at least 48 fish species from the northern hemisphere, including North America, Asia and Europe, and fifteen different species including herring, sprat, cod, Norway pout and flatfish from northern European waters. The high number of VHSV isolations from the Baltic Sea, Kattegat, Skagerrak, the North Sea and waters around Scotland indicate that the virus is endemic in these waters. The VHSV isolates originating from wild marine fish show no to low pathogenicity to rainbow trout and Atlantic salmon, although several are pathogenic for turbot. Marine VHSV isolates are so far serologically indistinguishable from freshwater isolates. Genotyping based on VHSV G- and N-genes reveals four groups indicating the geographical origin of the isolates, with one group representing traditional European freshwater isolates and isolates of north European marine origin, a second group of marine isolates from the Baltic Sea, a third group of isolates from the North Sea, and a group representing North American isolates. Examples of possible transfer of virus from free-living marine fish to farmed fish are discussed, as are measures to prevent introduction of VHSV from the marine environment to aquaculture.

The Citarum River in West Java is the largest water supplier to the Saguling Dam, which plays a major role in electric power generation for the entire Java Island and is used for the aquaculture of marketed fish. To elucidate the extent of degradation in water quality and its causes in the Upper Citarum watershed, physical, chemical and biological parameters for water samples collected from various sites were analyzed. The results demonstrate large site-to-site variations in water qualities and pollutant loads derived from various human activities such as agriculture, cattle raising and the textile industry. To halt worsening conditions of the Citarum watershed, integrated mitigation efforts should be made, taking biophysical pollution mechanisms and local socioeconomic conditions into account.

The South American lungfish, Lepidosiren paradoxa inhabits seasonal environments in the Central Amazon and Paraná-Paraguay basins that undergo significant oscillations in temperature throughout the year. They rely on different gas exchange organs, such as gills and skin for aquatic gas exchange while their truly bilateral lungs are responsible for aerial gas exchange; however, there are no data available on the individual contributions of the skin and the gills to total aquatic gas exchange in L. paradoxa. Thus, in the present study we quantify the relative contributions of skin and gills on total aquatic gas exchange during warm (35°C) and cold exposure (20°C) in addition to the effects of aerial and aquatic hypercarbia on aquatic gas exchange and gill ventilation rate (fG; 25°C), respectively. Elevated temperature (35°C) caused a significant increase in the contribution of cutaneous (from 0.61±0.13 to 1.34±0.26ml. STPD.h(-1)kg(-1)) and branchial (from 0.54±0.17 to 1.73±0.53ml. STP...

The pathogenic oomycete Aphanomyces invadans is the primary etiological agent in ulcerative mycosis, an ulcerative skin disease caused by a fungus-like agent of wild and cultured fish. We developed sensitive PCR and fluorescent peptide nucleic acid in situ hybridization (FISH) assays to detect A. invadans. Laboratory-challenged killifish (Fundulus heteroclitus) were first tested to optimize and validate the assays. Skin ulcers of Atlantic menhaden (Brevoortia tyrannus) from populations found in the Pamlico and Neuse River estuaries in North Carolina were then surveyed. Results from both assays indicated that all of the lesioned menhaden (n = 50) collected in September 2004 were positive for A. invadans. Neither the FISH assay nor the PCR assay cross-reacted with other closely related oomycetes. These results provided strong evidence that A. invadans is the primary oomycete pathogen in ulcerative mycosis and demonstrated the utility of the assays. The FISH assay is the first molecula...

Channichthyid icefishes of Antarctica are unique among adult vertebrates. All icefish species lack hemoglobin and red blood cells in their circulating blood. All icefishes examined to date also lack the intracellular oxygen-binding protein myoglobin (Mb) in their oxidative skeletal muscles. However, some icefish species do express Mb in their heart ventricles. It is unknown whether Mb in those species in which it is present represents an evolutionary relic or has functional significance. To address this problem, we compared mechanical performance of isolated, perfused hearts from two species of icefish in which Mb is either present (Chionodraco rastrospinosus) or is absent (Chaenocephalus aceratus). Hearts were challenged with increasing afterload (2.5-4.0 kPa) under conditions of defined basal flow (approximately 100 ml.min-1.kg-1), in both the presence and absence of 5 mM sodium nitrite, a Mb poison. Unlike hearts from C. aceratus, which were unable to maintain a constant cardiac ...

ObjectiveDespite widespread concern over exploitation of the European Union's fish stocks, dietary guidelines in the UK continue to recommend two portions of fish per week. The present study sought to investigate whether health and/or sustainability are motivating factors when purchasing and consuming fish and whether there are sociodemographic trends.DesignA structured, self-completion postal questionnaire exploring consumers’ attitudes towards purchasing fish, their dietary intake, stated purchasing behaviour and sociodemographic information.SettingNottinghamshire, UK.SubjectsAdults from 842 households randomly selected from the electoral register.ResultsOver half of the participants (57·0 %) were aware of the health benefits of fish consumption and reported health as a primary motivator for purchasing fish; however, only 26·8 % actively sought to purchase fish from a sustainable source (e.g. Marine Stewardship Council (MSC) certified fish). Only 30·6 % of participants met cur...

Studies were conducted from May, 1993 to April, 1995 to determine the changing patterns of infection by the liver fluke, Clonorchis sinensis, among residents and fish hosts in Kyongbuk Province. The infection rate among residents was 7.7% by stool examination. The rate in males (11.3%) was significantly higher than females (4.1%). Positive rate of intradermal test was 27.6% in the same population. The special type of a simple catalytic model was applied for the analysis of intradermal positive reactors by age and sex, and the equation was y = 0.4776 (1 - e-0.0375t) for males and, y = 0.2085 (1 - e-0.0138t) for females. Analysis of stool examination data by two-stage catalytic model revealed y = 0.025 (e-0.00471 - e-0.0235t). The annual Clonorchis infection rate was 4.7 per 1,000 susceptibles and the annual loss rate was 23.5 per 1,000 infected. The frequency distribution by the eggs per gram (EPG) was calculated as well as the cumulative percentages of positives. The regression equa...

SUMMARY In tetrapods, arginine vasopressin and its counterpart, arginine vasotocin(AVT), are involved in renal water conservation through vascular V1a-type and tubular V2-type receptors, and only the former has thus far been cloned in fish. We successfully cloned the V1a-type and V2-type AVT receptor from the kidney of the African lungfish, Protopterus annectens, and the deduced amino acid sequences exhibited high homology with amphibian V1a- and V2-type receptors, respectively. Functional analysis showed that AVT addition to CHO cells transfected with lungfish V1a-type receptor increased[Ca2+]i in a concentration-dependent manner, whereas CHO cells transfected with lungfish V2-type receptor responded with cAMP accumulation after AVT stimulation. Lungfish V2-type receptor mRNA was strongly expressed in the heart and kidney, while V1a-type receptor mRNA was ubiquitously expressed in all the tissues examined. In the kidney,immunohistochemistry using a specific antibody to lungfish V2-...

Aims:  The development and evaluation of a protocol based on polymerase chain reaction (PCR) and nucleic acid hybridization techniques for the specific detection of lymphocystis disease virus (LCDV) in several marine fish species.Methods and Results:  The pair of primers for PCR, OBL3 and OBL4, was designed based on published nucleotide sequence (LCDV-1) and amplifies a fragment within the major capsid protein. The sensitivity was evaluated using DNA from purified viral particles, as well as from cells inoculated with several viral concentrations. The PCR combined with slot blot was the most sensitive methodology, detecting 2·5 ng of viral DNA. Using this methodology LCDV was detected at 5 days postinoculation from SAF-1 cells initially inoculated with 10−5 TCID50 ml−1. The combination of PCR with membrane hybridization has also been proved to be adequate to detect LCDV from apparently healthy carriers by means of caudal fin sample analysis. This asymptomatic infection was also demonstrated by classical virological methods (cell culture and immunoblot).Conclusions:  The protocol described in this study allows the specific detection of LCDV, both in cell cultures and in fin homogenates from asymptomatic fish.Significance and Impact of the Study:  The detection of asymptomatic carriers by a rapid molecular method using caudal fin sampling, which does not imply animal killing, could be an important tool to control epizootics caused by LCDV, as fish could be analysed before their introduction and/or mobilization in farm facilities.

We have initiated a genetic analysis of the zebrafish visual system to identify novel molecules involved in vertebrate retinal function. Zebrafish are highly visual; they have four types of cones as well as rod photoreceptors, making it possible to study both rod and cone-mediated visual responses. To identify visual mutants, optokinetic responses of mutagenized larvae are measured in a three-generation screen for recessive mutations. By measuring visual behavior our genetic screen has been targeted towards identifying mutants that do not have gross morphological abnormalities. The electroretinogram (ERG) of optokinetic-defective mutants is recorded and their retinas are examined histologically to localize defects to the retina. In this report, we summarize our screening results and ERG and histological analyses of the five morphologically normal mutants we have analyzed to date. Additionally, the more detailed characterization of a red-blind mutant that we have isolated is summariz...

Fish communities and habitat structures were evaluated by underwater visual censuses a rocky location impacted by thermal discharge (I) and at two control locations, one in a Sargassum bed (C1) and the other in a rocky shore with higher structural complexity (C2). Habitat indicators and fish communities exhibited significant differences between the impacted and control locations, with the impacted one

Although the majority of teleost fishes possess a fused lower jaw (or mandible), some lineages have acquired a secondary joint in the lower jaw, termed the intramandibular joint (IMJ). The IMJ is a new module that formed within the already exceptionally complex teleost head, and disarticulation of two bony elements of the mandible potentially creates a "double-jointed" jaw. The apparent independent acquisition of this new functional module in divergent lineages raises a suite of questions. (1) How many teleostean lineages contain IMJ-bearing species? (2) Does the IMJ serve the same purpose in all teleosts? (3) Is the IMJ associated with altered feeding kinematics? (4) Do IMJ-bearing fishes experience trade-offs in other aspects of feeding performance? (5) Is the IMJ used to procure prey that are otherwise unavailable? The IMJ is probably under-reported, but has been documented in at least 10 lineages within the Teleostei. Across diverse IMJ-bearing lineages, this secondary...

Theoretical and laboratory studies generally show that ectotherm performance increases with temperature to an optimum, and subsequently declines. Several physiological mechanisms probably shape thermal performance curves, but responses of free-ranging animals to temperature variation will represent a compromise between these mechanisms and ecological constraints. Thermal performance data from wild animals balancing physiology and ecology are rare, and this represents a hindrance for predicting population impacts of future temperature change. We used internally implanted accelerometers near the middle of a species' geographical distribution and gill-net catch data near the species' latitudinal extremes to quantify temperature-related activity levels of a wild predatory fish (Platycephalus fuscus). We examined our data in…