Platichtys Flesus Research Articles

Fecundity regulation in relation to habitat utilisation of two sympatric flounder (Platichtys flesus) populations in the brackish water Baltic Sea

Two populations of flounder (Platichtys flesus) with different life history traits inhabit the brackish water Baltic Sea. Both types share feeding areas in coastal waters during summer-autumn but utilise different habitats for spawning in spring, namely offshore spawning with pelagic eggs and coastal spawning with demersal eggs respectively. Fecundity regulation by atresia was assessed as prevalence (portion of fish with atresia) and intensity (calculated as the average intensity of atresia in these fish) during the reproductive cycle following start of gonad development in the autumn up to spawning in spring, and evaluated in relation to fish condition (Fulton's condition factor reflecting energy reserves of the fish) and feeding incidence of the respective population. Peaking in winter (December–February), fecundity regulation was significantly higher for coastal spawning flounder than for flounder spawning offshore. For coastal spawners, the prevalence was 45–90% with an intensity of 6.4–9.3% vs. 0–25% and an intensity of 2.1–3.4% for offshore spawners during winter. Further, fecundity regulation ceased prior to spawning for offshore spawners but continued for coastal spawners. For coastal spawners, the prevalence was 12–29% and an intensity of 2.5–6.1% during spawning. The change in fish condition was strongly related to feeding incidence and differed between populations. As feeding ceased, condition of offshore spawners decreased during winter up to spawning, whereas condition of coastal spawners decreased during autumn but was maintained as feeding started again prior to spawning. Thus, habitat utilisation according to spawning strategy affects the timing of fecundity down-regulation reflecting availability of resources, namely limited food resources in deep areas and higher availability in coastal areas. Offshore spawning flounder display characteristics typical for a capital spawner with ceasing of feeding and oocyte down-regulation well before spawning, whereas coastal spawning flounder can be characterised as intermediate between a capital and income spawner with feeding prior to and during spawning along with continuous fecundity-regulation.

An orphan viral TNF receptor superfamily member identified in lymphocystis disease virus

BackgroundLymphocystis disease virus (LCDV) is a large icosahedral dsDNA-containing virus of the Lymphocystivirus genus within the Iridoviridae family that can cause disease in more than 140 marine and freshwater fish species. While several isolates have been charcaterized and classified into distinct genotypes the complete genomic sequence is currently only available from two species, the LCDV-1, isolated from flounder (Platichtys flesus) in Europe and the LCDV-C, isolated from Japanese cultured flounder (Paralichthys olivaceus) in China. Analysis of the genome of LCDV-C showed it to encode a protein named LDVICp016 with similarities to the Tumour necrosis factor receptor (TNFR) superfamily with immunomodulatory potential.FindingsWe have expressed and purified the recombinant protein LDVICp016 and screened for potential interaction partners using surface plasmon resonance. Commercially available human and mouse members of the TNF superfamily (TNFSF), along with a representative set of fish-derived TNFSF were tested.We have found the LDVICp016 protein to be secreted and we have identified a second viral TNFR encoded by ORF 095 of the same virus. None of the 42 tested proteins were found to interact with LDVICp016.ConclusionsWe show that LDVICp016 is a secreted protein belonging to the TNF receptor family that may be part of a larger gene family in Lymphocystiviruses. While the ligand of this protein remains unknown, possibly due to the species specific nature of this interaction, further investigations into the potential role of this protein in the blockade of immune responses in its fish host are required.

Modelling towing and haul-back escape patterns during the fishing process: a case study for cod, plaice, and flounder in the demersal Baltic Sea cod fishery

Abstract Herrmann, B., Mieske, B., Stepputtis, D., Krag, L. A., Madsen, N., and Noack, T. 2013. Modelling towing and haul-back escape patterns during the fishing process: a case study for cod, plaice, and flounder in the demersal Baltic Sea cod fishery. – ICES Journal of Marine Science, 70: 850–863. The survival likelihood of fish escaping through trawl codends may depend on when they escape. It is therefore relevant to investigate when during the fishing process fish actually attempt to escape and do escape from trawl codends. This subject is addressed by modelling data collected during a specially designed experiment. Results demonstrate that the escape process during towing cannot be described sufficiently by a traditional logistic model or something similar. Instead, a model is required that explicitly considers that not all fish necessarily contact the codend netting to attempt escape during the towing phase. A model that accounts for such behaviour is applied and it is demonstrated that this model can adequately describe the size selection process during towing. The overall escape process, which consists of the attempt probability, partial escape during towing, and partial escape during the haul-back phase, is also modelled. This proposed model sufficiently described the observed escape pattern for cod (Gadus morhua), plaice (Pleuronectes platessa), and flounder (Platichtys flesus). For all three species, a significant percentage of the individuals entering the codends during fishing first attempt to escape during the haul-back operation.

Fish pollution with anthropogenic 137Cs in the southern Baltic Sea

This paper presents the results of a study on changes in 137Cs activity concentrations in three fish species from the southern Baltic Sea: cod (Gadus morhua), herring (Clupea harengus) and flounder (Platichtys flesus), in the period 2000–2010. During the study period a marked decline in cesium activity concentration in fish muscle tissue was observed, which reflected changes in radionuclide activity concentration in seawater. No statistically significant temporal trends were determined in changes of concentration factors (CFfish/seawater) calculated for the examined fish species. The analysis of 137Cs activity as a function of ichthyological parameters revealed the lack of a relationship between radionuclide activity concentrations in herring muscle tissue and the fish age in an narrow age range (2–4years). However, a reverse proportionality of total fish mass, as well as body length, against 137Cs activity concentrations in muscles was well documented. The latter observation can be the direct result of the dilution effect related to the increase of fish body weight. 137Cs activity concentration in muscle tissue of the five fish species forms a declining sequence: Gadus morhua, Platichthys flesus, Clupea harengus, Perca fluviatilis and Neogobius melanostomus.

Bioaccumulation of mercury in the trophic chain of flatfish from the Baltic Sea

Mercury concentrations in three flatfish species – flounder (Platichtys flesus), plaice (Pleuronectes platessa), and Baltic turbot (Scophthalmus maximus), netted in the southern Baltic Sea were assessed and compared to concentrations of this metal in sediments, sea water, and flatfish food – bivalve Macoma balthica, isopod Saduria entomon, and sprat (Sprattus sprattus). Collected simultaneously with flatfish in 2009 and 2010. Different concentrations of mercury depending on species, tissue or organ, sex, individual length, kind of food, and region were determined. The muscle tissues of turbot had the highest concentrations of the metal. The bioaccumulation (BF) and biomagnification (BMF) factors has been counted showing that the muscle tissues of turbot have maximum affinity for mercury, and thus best reflected the metal contamination of the Baltic Sea environment. The data suggest that the common Baltic turbot (S. maximus) is an important model species, suitable and cost-effective to biomonitor environmental mercury pollution for ecological research.

Seasonal variation in length, weigth, and sex distribution of flounder (Platichtys flesus luscus Pallas, 1871) in the south-eastern black sea

The length, weight and sex distribution of flounder caught by bottom trawl were investigated in relation with seasons in the south-eastern Black Sea (oof Trabzon). The size ranges were 12.027.9 cm and 11.2-38.2 cm for male and female flounder, respectively. Mean total length and weight were 27.6±3.61 cm and 248.0±91.25 g for females, 21.1±1.86 cm and 103.4±27.23 g for males, and 24.2±4.30 cm and 172.1±97.88 g for all individuals. Significant differences were found both in length and weight values of flounder between seasons. The length frequencies of flounder differed significantly between spring and other seasons (P < 0.001). Significant differences were found for sex ratios of flounder in spring. The length-weight relationship for females, and males were estimated as W = 0.0184 * L (r = 0.90), and W = 0.0202 * L (r = 0.87), respectively.

Environmental factors structuring fish composition and assemblages in a small macrotidal estuary (eastern English Channel)

The fish assemblage structure was analyzed along an estuarine gradient of a small macrotidal estuary (the Canche, France). Fishes were collected every two months between May 2006 and July 2007 from 12 sampling stations using a 1.5-m beam trawl with a 5 mm mesh size in the cod end. To complement this information, sampling was also performed using 15-m fyke nets (8 mm mesh size in the cod end). For each sample, abiotic (temperature, salinity, pH, oxygen, turbidity, river flow, wind speed and depth) and biotic (macro crustacean species abundances) were recorded. Throughout the study, 28 fish species belonging to 20 families were collected. Fish catches were dominated by juveniles, especially Young-Of-the-Year (YOY) for the majority of the species. According to the Index of Relative Importance (IRI), common goby Pomatoschistus microps, flounder Platichtys flesus, sprat Sprattus sprattus, sea-bass Dicentrarchus labrax and plaice Pleuronectes platessa were the most abundant species, together accounting for 99.2% of the total IRI. Estuarine residents (ER = 66.2%) and marine juvenile migrants species (MJ = 31.4%) were the most important ecological guilds. The structure of the fish assemblage and its relationship to environmental variables was examined using multivariate techniques. Cluster and non-metric multidimensional scaling (nMDS) analysis defined six distinct groups in the Canche estuary, which are discriminated by specific species (SIMPER). Spatio-temporal variations in fish assemblage structure reflect the density peaks of the most abundant species. Spearman rank correlations and canonical correspondence analysis (CCA) showed that among the ten environmental variables examined, temperature, salinity and Crangon crangon (a potential predator for YOY fish or prey for older ones) are the three most important factors influencing fish species richness and abundances. Our observations reinforce the idea that certain fish species may have different life history styles in different geographic areas. The present study highlights the necessity of a better knowledge of the connectivity between estuaries and adjacent marine areas. The Canche constitutes an important ecosystem for fishes and as it is subject to little anthropogenic disturbance; its ichthyofauna can be viewed as a reference or normal assemblage for small temperate macrotidal estuaries.

Effects of TNT leakage from dumped ammunition on fish and invertebrates in static brackish water systems

The objective of the present study was to study the release and effect of TNT from dumped ammunition. Cleaved artillery shells were placed in static brackish water systems for 5 months, and another 12 months with 5 cm sediment burial. The toxicity was determined in bioassays with crustaceans ( Nitocra spinipes and Hyalella azteca) and/or European flounder ( Platichtys flesus). The water phase was analysed for TNT using colorimetric method and GC-MS. This study showed a rapid release of TNT to acutely toxic concentrations when the cleaved ammuniton was not covered with sediment under static conditions, but that the release was effectively inhibited by sediment burial of the artillery shells. Hence, at least in a short-term perspective, acute adverse effects of sediment-buried ammunition on aquatic organisms should be greatly reduced.

Estimation of grey seal (&lt;i&gt;Halichoerus grypus&lt;/i&gt;) diet composition in the Baltic Sea

We examined the digestive tract contents from 145 grey seals (Halichoerus grypus) collected between 2001 and 2004 in the Baltic Sea. We compensated for biases introduced by erosion of otoliths, both by using additional hard-part structures other than otoliths, and species-specific size and numerical correction factors. In the absence of numerical correction factors based on feeding experiments for some species, we used correction factors based on a relationship between otolith recoveryrate and otolith width. A total of 24 prey taxa were identified but only a few species contributed substantially to the diet. The estimated diet composition was, independently of the prey number estimation method and diet composition estimation model used, dominated by herring (Clupea harengus), both by numbers and biomass. In addition to herring, common whitefish (Coregonus lavaretus) and sprat (Sprattus sprattus) were important prey, but cyprinids (Cyprinidae), eelpout (Zoarces viviparus), flounder (Platichtys flesus) and salmon (Salmo salar) also contributed significantly. Our results indicated dietary differences between grey seals of different age as well as between seals from the northern (Gulf of Bothnia) and the southern (Baltic Proper) Baltic Sea.

Fate and Effects of 2,4,6-Trinitrotoluene (TNT) from Dumped Ammunition in a Field Study with Fish and Invertebrates

2,4,6-Trinitrotoluene (TNT) is the major explosive ingredient in ammunition dumped into lakes and sea after World War II. The aim of the present field study was to study the fate and effect of TNT and its degradation products from dumped ammunition. Artillery shells were cleaved longitudinally to expose TNT and placed in open boxes filled with sediment, and then placed at the sea bottom. Sediment samples were taken in each box at the start and after 3, 9, 13, 20, 24, 33, and 36 months, and the sediments were tested for toxicity with bioassays using Nitocra spinipes (96 h), Hyalella azteca (96 h), and Daphnia magna (24 and 48 h). The result from the bioassays showed no impact of dumped ammunition on the survival of H. azteca and mobility of D. magna. Bioassays with N. spinipes showed significant differences in toxicity between control boxes and boxes with shells after 9 months and thereafter. The mean mortality (+/- SD) of N. spinipes in boxes with shells was 63 +/- 22%, and the mortality in control boxes was 23 +/- 17%. No continuous increase in sediment toxicity over time was found. After 3 years, cages with European flounder (Platichtys flesus) and blue mussels (Mytilus edulis) were attached to the boxes. The fish were examined for biochemical and physiological effects 8 weeks later. Exposure to ammunition, which had rested on the sea bottom 3 years, caused no significant effects on body indices, hematological variables, and detoxification and antioxidant enzymes activities in the flounder. The sediment, bile, and blood plasma of exposed fish, and hepatopancreas of exposed mussels, contained no detectable levels of TNT and its metabolites. Only minor disappearance of TNT from the shells could be detected by visual inspection on site (by scuba divers). This study suggests that the survival of sensitive benthic organisms, e.g., N. spinipes, might be negatively affected at an ammunition dumping site.

Identification and quantification of n-octyl esters of alkanoic and hexanedioic acids and phthalates as urban wastewater markers in biota and sediments from estuarine areas

A gas chromatographic method for the identification and quantification of n-octyl esters (from n-octyl tetradecanoate to n-octyl hexacosanoate including dioctyl hexanedioate) and phthalates [dibutyl phthalate, benzyl butyl phthalate and di(2-ethylhexyl) phthalate] in sediments and biota from estuarine environments is described. Standards used for identification and quantification of some n-octyl esters were synthesized. The method has allowed the analysis of these compounds in polychaeta ( Nereis diversicolor), oysters ( Crassostea angulata), crabs ( Carcinus maenas) and fish ( Chelon labrosus, Platichtys flesus and Chondostroma polylepis) that were collected at different locations of the Urdaibai estuary (Bizkaia, Basque Country, Spain). Total phthalates and n-octyl esters ranged between 0.01 and 12 μg g −1 and 0.05 and 9.4 μg g −1, respectively, and were predominantly found in polychaeta and fish. Sediments did not contain these compounds in significant amount, only benzyl butyl phthalate, dioctyl hexanedioate and di(2-ethylhexyl) phthalate were found above limit of detection (0.01–0.05 μg g −1).

Long-term Changes of a Brackish-water Eelgrass (Zostera marina L.) Community Indicate Effects of Coastal Eutrophication

The distribution and importance of eelgrass (Zostera marina L.) meadows for associated faunal communities in the coastal waters of the Baltic Sea are still poorly known. In these low-saline (5–7), shallow coastal areasZ. marina grows at its limit of distribution, forming mostly patchy meadows. In June 1993, a seagrass locality (Tvärminne, SW Finland) thoroughly studied in 1968–71 was revisited in order to detect possible long-term changes in both vegetation structure (distribution, density, biomass) and benthic fauna (species composition, abundance, biomass, distribution and diversity patterns). The same sampling design as in the 1970s was used in both sparse (<20 shootsm−2) and dense (>150 shootsm−2) Z. marina. In addition, the feeding-efficiency of adult flounder (Platichtys flesus L.) on infauna was measured by counting feeding pits in vegetated and bare sand. The analysis shows that the shoot density had increased in sparse Z. marina, while dense Z. marina patches showed similar biomass values (20gAFDWm−2) as in the 1970s. In contrast to the vegetation, where little apparent change could be recorded, the total abundance and biomass of zoobenthos has increased significantly between 1968–71 and 1993 in the dense Z. marina patches. These changes are mainly attributed to significant increases of the bivalve Macoma balthica L., mudsnails Hydrobia spp. and oligochaetes. In sparseZ. marina diversity in terms of number of taxa exhibited minor changes over time, whereas in dense Z. marina patches the mean number of taxa has increased from 16 to 20. The vegetation cover was sufficient to reduce significantly the predation effects of flounder on seagrass infauna. This study represents a rare example of long-term persistence of seagrass communities in an area where the negative effects of nutrient enrichment are evident. The faunal changes in the Z. marina community indicate increased food availability, which is associated with positive effects of coastal eutrophication.

Disorder and recovery of environmental health monitored by means of lysosomal stability in liver of European flounder (Platichthys flesus L.)

From 1995 to 2000 biological effects were studied in liver of flounder (Platichtys flesus L.) from the German Bight. During the study period deleterious consequences of acute discharges of DDT and PCBs in early spring 1996 and after 1998 due to remobilization of contaminants from riverbed deepening of the River Elbe became evident. As core biomarker which reflects toxically induced liver pathologies and integrates effects of various classes of pollutants we measured the integrity of lysosomal membranes in individual flounder liver. During the study period, twice statistically significant disturbances of lysosomal function was detected in fish from the River Elbe: in summer 1996 and in spring 1999. Yet, the detrimental contaminant effects were not only restricted to individuals from the Elbe but expanded to those flounder inhabiting formerly less polluted reference areas. In contrast to flounder of the Elbe, their ability to recover from the lysosomal disorders were limited. While in autumn 2000 Elbe individuals showed clear signs of recovery, those fish caught in areas more distant to the source of toxicant input still maintained significantly decreased lysosomal membrane integrity. It can be speculated that fish populations which are not continuously exposed to chronic anthropogenic stress may have a lower potential or need a longer period to recover from the effects of pollution.

Halogenated environmental contaminants in fish from Estonian coastal areas

Polychlorinated biphenyls (PCBs), DDT-related substances and hexachlorocyclohexane (HCH) isomers were analysed in fish from Estonian coastal waters.The content of persistent organic pollutants (POPs) in fish (perch ( Perca fluviatilis) and flounder ( Platichtys flesus)) from the coastal waters of Estonia is not a danger to human health. Even the maximum concentrations that we have determined are lower than the standards set by the World Health Organization (WHO). The results do not exclude the need to monitor toxicants in fish also in the future, because the use of hazardous chemicals in the Baltic Sea region will probably continue.

Feeding traces and bioturbation by birds on a tidal flat, Dutch Wadden Sea

Gulls (mainly Larus ridibundus) and Shelducks (Tadorna tadorna) make characteristic feeding traces on the Dutch tidal flat studied. Troughs up to 3 m long, ca. 15 cm wide, and ca. 3 cm deep made by L. ridibundus were most frequent from July to October. Craters made by Shelducks, ca. 10 cm deep and up to 60 cm in diameter, were most common in summer. The larger craters compare well with feeding traces reported for Eider ducks (Somateria mollissima) and rays (Hypotremata); the smaller craters compare with those of Flounder (Platichtys flesus) and Bream (Abramis brama). All illustrate uniformity in origin: benthic feeding by predators. Annually ca. 30% of the area studied was reworked by gulls and ca. 15% was reworked by Shelducks. The annual sediment reworking rate by these birds equals a sediment layer 2.5 cm thick. This volume is about one order of magnitude less than the ∼35 cm reworked annually by the most important deposit feeders of this tidal flat, collectively: the polychaetes Arenicola marina and Heteromastus filiformis and the bivalve Macoma balthica.

Locomotor activity patterns of nineteen fish and five crustacean species from the Baltic Sea

Activity patterns of some common Baltic fish species and macrocrustaceans have been investigated in natural light/dark conditions — in most cases for periods of at least one full year. The fauna of the northern Baltic proper consists of species of both marine and freshwater origin, with both types represented in the study. The different patterns found are discussed in relation to light period, light intensity and to the structure and function of the eyes. The following species were considered nocturnal: Idothea baltica, Mesidothea entomon, Gammarus oceanicus, Palaemon adspersus, Anguilla anguilla, Spinachia spinachia, Pholis gunnellus, Zoarces viviparus, Scopthalmus maximus, and Platichtys flesus. These species were considered diurnal: Clupea harengus, Scardinius erythrophthalmus, Gasterosteus aculeatus, Perca fluviatilis, Gobius niger, Taurulus bubalis, and Cyclopterus lumpus. The next three species showed a crepuscular pattern of activity: Praunus flexuosus, Esox lucius and Gymnocephalus cernus. Four species were considered to show inversions of the activity patterns: Pungitius pungitius, Pomatoschistus minutus, Myoxocephalus scorpius and M. quadricornis.

Mercury in flounder,Platichtys flesus, cod,Gadus morhua, and perch,Perca fluviatilis, in relation to their length and environment

During the last ten years several changes have been taken place in the use of mercury. Industrial discharges have been restricted and several fields of application have been eliminated or reduced. However, the use of mercury containing batteries is still increasing. Monitoring the mercury content of fish is however still an important aspect of environmental pollution control. It has been shown by several investigators that the mercury content in fish might be correlated with biological parameters like length and age. In this paper the results are presented of a few recent Dutch monitoring studies of mercury in flounder, cod and perch in relation to biological and environmental parameters.

Random Prey Capture or Active Choice? An Experimental Study on Prey Size Selection in Three Marine Fish Species

Prey size selection was studied in the marine fishes Pomatoschistus microps, P. minutus, and Platichtys flesus. Three size classes of the amphipod Corophium volutator were used as prey in laboratory experiments, and field samples were taken to compare Corophium size in the fish stomachs and in the surrounding environment. When there were equal numbers of the different prey sizes in the aquaria, P. minutus and P. flesus ate an increasing proportion of large Corophium as prey density increased. P. microps were offered the Corophium size-classes in different proportions. When there were equal numbers of the size-classes, P. microps showed a strong preference for large prey, but as small prey increased in abundance, selectivity decreased and prey choice became random. In the field, small Corophium were more abundant than the other size-classes. P. microps and P. minutus ate this prey most frequently, while P. fiesus ate more medium-sized Corophium. For P. minutus and P. flesus mean prey size increased with increasing fish size in the laboratory experiments. Prey size selection was thus influenced by absolute and relative densities of prey and by predator size. Differences in visibility and evasion capability of different sizes of prey also affected the food choice of the fishes in this study.

Calcium paradox from cyclostome to man: a comparative study

1. 1. In seven poikilotherm species, i.e. cyclostome, Myxine glutinosa; teleosts, Gadus morrhua; Platichtys flesus; amphibia, R. pipiens; R. temporaria; Xenopus laevis; reptiles, Vipera berus. Ca paradox could not be obtained in ventricular strips at 8–12°C. 2. 2. In similar preparations from human atria at 30°C and 37°C, Ca paradox was obtained similarly as in other homoiotherms. 3. 3. In homoiotherms, lowered temperature (below 30°C) has a protective effect. Viper myocardium did not display Ca paradox at 12, 22 or 32°C, whereas human myocardium displayed Ca paradox even at 30°C. 4. 4. It is postulated that the absence of Ca paradox in poikilotherms is not due to the low temperature. 5. 5. In hagfish ( Myxine glutinosa) the absence of Ca paradox seems to be due to the specific conditions concerning Ca exchange in the myocardial cell (large glycocalyx).

A time course study of the effect of repetitive doses of estradiol-17β on serum glucose and lipids, liver glycogen and some carbohydrate metabolizing enzymes in liver of male flounder ( Platichtys flesus L.)

1. 1. Repeated treatment of male flounder with 5 and 100 μg doses of estradiol-17β increases the level of phospholipid, triglyceride, free fatty acids and total lipid in serum as a function of time and dose, during a period of 17 days. 2. 2. The glucose level in serum is increased and decreased respectively by doses of 5 and 100 μg. 3. 3. Five and 100 μg doses decrease the level of glycogen in liver. 4. 4. Five μg doses do not affect the activity of the measured enzymes considerably, with the exception of phosphorylase a. 5. 5. One hundred μg doses increase the activity of glucose-6-phosphate dehydrogenase after 11 days. 6. 6. One hundred μg doses increase the activity of pyruvate kinase continuously during the experimental period and decrease phosphorylase a and glucose-6-phosphatase activity.