The Importance of Ship Hull Fouling as a Vector of Species Introductions into the North Sea

Ships have long been recognized as a major vector for the introduction of non-native and harmful organisms. From 1992 to 1996 a shipping study was undertaken in Germany, focusing on the fauna transported by ships, to assess the importance of species introductions by international shipping traffic. Ballast water, tank sediment or hull fouling of 186 vessels was sampled. A total of 257 species were identified, ranging from Foraminifera to Teleostei, and 57% of the species sampled were considered to be non-native to the North Sea region, originating from elsewhere in the world including the north eastern Atlantic (west of the English Channel). Non-native species were recorded in 38% of all ballast water samples, 57% of all sediment samples and 96% of all hull samples, indicating that hull fouling is an important vector of introduction. Four species (1.6%) of unknown origin (cryptogenic species) were identified. The potential for establishment in the North Sea region of all non-native species found was classified into three categories based on the degree of similarity of climatic conditions in the North Sea and the donor region. Based on this criterion 19 of the species found in the fouling communities on ships' hulls were deemed to have a high potential for establishment in the North Sea.     

Mesocosm experiments: mimicking seasonal developments of microbial variables in North Sea sediments

This study investigated the suitability of mesocosms for studying the seasonal development of microbial variables in the benthic system of the North Sea. Undisturbed sediment cores were taken from two locations in the North Sea, one with sandy sediment (28 m depth) and the other with silty sediment (38 m depth) and installed in mesocosms in January–April 1989. Cores were kept as in situ temperature in the dark until December 1989. One set of sandy and silty sediments was starved and the other set received a supply of organic matter in May–June, simulating the settlement of the spring bloom of Phaeocystis pouchetii. Seasonal developments in bacterial production (methyl ³H-thymidine incorporation), abundance and biomass of bacteria and nanoflagellates and oxygen consumption were compared between the mesocosms and the field in surface sediments every 1.5 to 2.5 months. Effects of seasonal temperature variations (range 6–17.5 °C) on microbial variables in starved mesocosms were limited, which possibly indicates a subordinate role of temperature in microbial processes in North Sea sediments. Organic matter produced a direct response in bacterial production and oxygen consumption in mesocosms. Bacterial and protozoan abundance also increased. The effect of the organic input disappeared within 2 months and values of enhanced variables declined to initial levels. The organic matter enrichment in mesocosms apparently did not provide sufficient energy to keep the microbenthos active at field levels through summer.These results suggest that in the silty sediments in the field, organic matter is available for bacterial production throughout summer. In sandy sediments, the major organic matter input, which sets the seasonal pattern, appears to be in June. Apparently the seasonal development of microbial variables can be mimicked in mesocosms with organic matter supplies. Differences between the field and mesocosms are further illustrated by carbon budgets. Recycling of bacterial biomass was required to meet the bacterial carbon demand in the budget.Publication No. 22 of the project Applied Scientific Research Neth. Inst. for Sea Res. (BEWON).     

The forth estuary: a nursery and overwintering area for North Sea fishes

The fish community of the Forth estuary, Scotland, has several components — estuarine resident species, diadromus migratory species, marine and freshwater adventitious species, marine juvenile migrants using the area as a nursery, and adults of marine species with seasonal migrations. The population changes during the period 1981–1988 in six species representative of the last two categories are described here. The species are the juvenile gadoids, whiting, Merlangius merlangus (L.) and cod, Gadus morhua L., juvenile flatfish, plaice, Pleuronectes platessa L. and common dab, Limanda limanda (L.), and the adult clupeids, sprat, Sprattus sprattus (L.) and herring, Clupea harengus L.The species' population changes are described in relation to aspects of wider significance such as commercial fishing for these species in North Sea areas. In particular, the underlying decline of the juvenile cod populations since 1981 in the Forth Estuary is discussed in relation to the recent reduction in commercial fishing quotas.     

Ulva (Chlorophyta,Ulvales) Biodiversity in the North Adriatic Sea (Mediterranean,Italy): Cryptic Species and New Introductions

Ulva Linnaeus (Ulvophyceae, Ulvales) is a genus of green algae widespread in different aquatic environments. Members of this genus show a very simple morphology and a certain degree of phenotypic plasticity, heavily influenced by environmental conditions, making difficult the delineation of species by morphological features alone. Most studies dealing with Ulva biodiversity in Mediterranean waters have been based only on morphological characters and a modern taxonomic revision of this genus in the Mediterranean is not available. We report here the results of an investigation on the diversity of Ulva in the North Adriatic Sea based on molecular analyses. Collections from three areas, two of which subject to intense shipping traffic, were examined, as well as historical collections of Ulva stored in the Herbarium Patavinum of the University of Padova, Italy. Molecular analyses based on partial sequences of the rbcL and tufA genes revealed the presence of six different species, often with overlapping morphologies: U. californica Wille, U. flexuosa Wulfen, U. rigida C. Agardh, U. compressa Linnaeus, U. pertusa Kjellman, and one probable new taxon. U. californica is a new record for the Mediterranean and U. pertusa is a new record for the Adriatic. Partial sequences obtained from historical collections show that most of the old specimens are referable to U. rigida. No specimens referable to the two alien species were found among the old herbarium specimens. The results indicate that the number of introduced seaweed species and their impact on Mediterranean communities have been underestimated, due to the difficulties in species identification of morphologically simple taxa as Ulva.     

The macrofauna of a stony sand area in the German Bight (North Sea)

The sublittoral macrofauna of the Steingrund, a stony area east-northeast of Helgoland, was investigated from May till October 1991 using a van Veen grab and a small dredge. The diverse endo- and epifauna of the sandy bottoms, pebbles and boulders of this Saalian end moraine comprised 289 taxa, whereby the polychaetesMagelona papillicornis, Lanice conchilega andSpiophanes bombyx dominated in terms of abundance. Species rare in the German Bight, such as the spongeLeucandra fistulosa, the sea urchinEchinus esculentus, and the sea anemoneHaliplanella lineata, were also found. The two sample sets were processed separately with multivariate techniques, and differentiated on the basis of occurrence and numbers of the abundant species. The analysis of the grab samples revealed two types of theTellina-fabula-community. These associations were differentiated by the presence of species of the coarse-sand-inhabitingGoniadella-Spisula-community and were related to the distribution of the grain size of the sediment. Likewise, two epifaunal assemblages were distinguished. Sandy bottoms were characterized byOphiura albida, Liocarcinus holsatus andPagurus bernhardus, while boulders and pebbles were covered by a varied sessile and mobile epifauna dominated by the sessile bryozoanFlustra foliacea and the mobile pantopodeAechelia echinata. Numerical density, biomass and annual production estimates are in the range of values determined for the macrobenthos of the German Bight, while annual P/B ratios mounted up to 5.     

Alien parasitic copepods in mussels and oysters of the Wadden Sea

Molluscan intestinal parasites of the genus Mytilicola, specifically M. intestinalis, were initially introduced into bivalves in the North Sea in the 1930s. It was presumably introduced from the Mediterranean with ship-fouling mussels, then attained epidemic proportions in Mytilus edulis in the 1950s and is now widely established in the North Sea region. Mytilicola orientalis was co-introduced with Pacific oysters to France in the 1970s and in the southern North Sea in the early 1990s. Its main host Crassostrea gigas has massively invaded the Wadden Sea with a concomitant decline in mussels. To explore whether introduced mytilicolid parasites could play a role in the shifting dominance from native mussels to invasive oysters, we analysed 390 mussels and 174 oysters collected around the island of Sylt in the northern Wadden Sea. We show that M. intestinalis has a prevalence >90% and a mean intensity of 4 adult copepods in individual mussels with >50 mm shell length at all sheltered sites. By contrast, none were found in the oysters. However, at one site, we found M. orientalis in C. gigas with a prevalence of 10% and an intensity of 2 per host individual (August 2008). This constitutes the most northern record in Europe for this Pacific parasite until now. Alignments of partial sequences of the mitochondrial cytochrome oxidase I (COI) gene and the nuclear internal transcribed spacers (ITS) and 18S rDNA sequences each show a distinct difference between the two species, which confirms our morphological identification. We suggest that the high parasite load in mussels compared to oysters may benefit the continued expansion of C. gigas in the Wadden Sea.     

Migration route and spawning area fidelity by North Sea plaice

Data from plaice, Pleuronectes platessa L., tagged with electronic data storage tags, were used to test whether these fishes exhibited migration route and spawning area fidelity in successive spawning seasons. Depth and temperature data were recorded for each fish over 365-512 days in the central North Sea and this information was used to reconstruct movements based on tidal locations. We discovered highly directed seasonal migrations from the winter spawning area south of a major topographical feature, Dogger Bank Tail End, to summer feeding grounds 250 km to the north in deep, cold, thermally stratified water. Our results show synchronous timing of migration, repeated pre- and post-spawning migration routes and 100% spawning area fidelity, including two individuals that returned to within 20 km of their previous season's spawning location. This is the first study to provide a complete reconstruction of annual migrations by individual fishes, showing strong homing behaviour along consistent migration routes.     

High mortality of Pacific oysters in a cold winter in the North-Frisian Wadden Sea

Mortality of introduced Pacific oysters (Crassostrea gigas) was studied in the northern Wadden Sea in response to an ice winter. After a decade of mild winters, in January and February 2010, the first severe winter occurred since the Pacific oysters became dominant on former intertidal blue mussel (Mytilus edulis) beds in the North-Frisian Wadden Sea. After the ice winter, mortality of Pacific oysters on densely populated beds in the List tidal basin reached about 90%, indicating much higher losses in comparison to former mild winters. At lower densities between the islands of Amrum and Föhr, oysters were less or even not affected. Although Pacific oysters are assumed to be very tolerant to frost, the duration of cold water- and air temperatures accompanied by mechanical stress of the ice burden might have caused the high mortality in the winter 2009/2010 in formerly dense beds.     

Amaranthaceae halophytes from the French Flanders coast of the North Sea: a review of their phytochemistry and biological activities

Halophytes are plant species that tolerate high salinity levels. To adapt to these particular abiotic conditions, they develop multiple physiological, biochemical and molecular mechanisms, including the biosynthesis of osmolytes, enzymes and specialized metabolites. The French Flanders coast of the North Sea is an ideal environment for this kind of plant. Amaranthaceae is one of the most represented botanical families of halophytes present on this coast, with 15 species belonging to 7 genera, namely Atriplex, Beta, Halimione, Kali, Oxybasis, Salicornia and Suaeda. Some of these species are well known as wild edible plants, and some are used in traditional medicine. This review examines the chemistry of these species and their potential for human health.

     

Biofouling in marine aquaculture: a review of recent research and developments

Biofouling in marine aquaculture is one of the main barriers to efficient and sustainable production. Owing to the growth of aquaculture globally, it is pertinent to update previous reviews to inform management and guide future research. Here, the authors highlight recent research and developments on the impacts, prevention and control of biofouling in shellfish, finfish and seaweed aquaculture, and the significant gaps that still exist in aquaculturalists’ capacity to manage it. Antifouling methods are being explored and developed; these are centred on harnessing naturally occurring antifouling properties, culturing fouling-resistant genotypes, and improving farming strategies by adopting more sensitive and informative monitoring and modelling capabilities together with novel cleaning equipment. While no simple, quick-fix solutions to biofouling management in existing aquaculture industry situations have been developed, the expectation is that effective methods are likely to evolve as aquaculture develops into emerging culture scenarios, which will undoubtedly influence the path for future solutions.     

Virus-contaminated oysters: a three-month monitoring of oysters imported to Switzerland

Molluscan shellfish are known to be carriers of viral and bacterial pathogens. The consumption of raw oysters has been repeatedly linked to outbreaks of viral gastroenteritis and hepatitis A. Switzerland imports over 300 tons of oysters per year, 95% of which originate in France. To assess the level of viral contamination, a 3-month monitoring study was conducted. Therefore, the sensitivities of several previously described methods for virus concentration were compared, and one protocol was finally chosen by using dissected digestive tissues. Eighty-seven samples consisting of five oysters each were analyzed for Norwalk-like viruses (NLVs), enteroviruses, and hepatitis A viruses from November 2001 to February 2002. The oysters were exported by 31 French, three Dutch, and two Irish suppliers. Eight oyster samples from six French suppliers were positive for NLVs, and four samples from four French suppliers were positive for enteroviruses; two of the latter samples were positive for both viral agents. No hepatitis A viruses were detected. The sequences of NLV and enterovirus amplicons showed a great variety of strains, especially for the NLVs (strains similar to Bristol, Hawaii, Mexico, and Melksham agent). The data obtained indicated that imported oysters might be a source of NLV infection in Switzerland. However, further studies are needed to determine the quantitative significance of the risk factor within the overall epidemiology of NLVs.     

Recent developments and biological activities of thiazolidinone derivatives: a review

Thiazolidinone is considered as a biologically important active scaffold that possesses almost all types of biological activities. Successful introduction of ralitoline as a potent anti-convulsant, etozoline as a antihypertensive, pioglitazone as a hypoglycemic agent and thiazolidomycin activity against streptomyces species proved potential of thiazolidinone moiety. This diversity in the biological response profile has attracted the attention of many researchers to explore this skeleton to its multiple potential against several activities. This review is complementary to earlier reviews and aims to review the work reported on various biological activities of thiazolidinone derivatives from year 2000 to the beginning of 2011. Data are presented for active compounds, some of which have passed the preclinical testing stage.     

Distribution of capsulated bacterioplankton in the North Atlantic and North Sea

In laboratory experiments, bacterioplankton were incubated under different nutrient conditions, and the percentage of bacteria exhibiting a polysaccharidic capsule (capsulated bacteria) and that of CTC (cyanotetrazolium chloride)-positive and therefore metabolically highly active bacteria were determined. In these seawater cultures amended with nutrients more than 95% of the CTC-positive cells exhibited a capsule. During two cruises, one to the North Atlantic and one to the North Sea, we investigated the distribution of capsulated bacteria throughout the water column. Capsulated bacteria were generally more abundant in eutrophic surface waters than in deeper layers or more oligotrophic regions. In the upper 100 m of the North Atlantic, about 6–14% of the total bacterioplankton community was capsulated, while in the layers below 100 m depth, 97% of the bacteria lacked a visible capsule. The percentage of capsulated bacteria correlated with bacterial abundance and production, and chlorophyll a concentration. Also, the bioavailability of DOC (dissolved organic carbon), estimated by the ratio between bacterial production and DOC concentration, significantly correlated with the percentage of capsulated bacteria. In the North Sea, the contribution of capsulated bacteria to the total number of bacteria decreased from the surface (3 m depth) to the near-bottom (25–35 m) layers from 20% to 14% capsulated bacteria. In the nearshore area of the North Sea, about 27% of the bacteria exhibited a capsule. Overall, a pronounced decrease in the contribution of capsulated bacteria to the total bacterial abundance was detectable from the eutrophic coastal environment to the open North Atlantic. Using this epifluorescence-based technique to enumerate capsulated bacterioplankton thus allowed us to routinely assess the number of capsulated bacteria even in the oceanic water column. Based on the data obtained in this study we conclude that almost all metabolically highly active bacteria exhibit a capsule, but also some of the metabolically less active cells express a polysaccharide capsule detectable with this method.     

Recent developments in genomewide association scans: a workshop summary and review

With the imminent availability of ultra-high-volume genotyping platforms (on the order of 100,000-1,000,000 genotypes per sample) at a manageable cost, there is growing interest in the possibility of conducting genomewide association studies for a variety of diseases but, so far, little consensus on methods to design and analyze them. In April 2005, an international group of >100 investigators convened at the University of Southern California over the course of 2 days to compare notes on planned or ongoing studies and to debate alternative technologies, study designs, and statistical methods. This report summarizes these discussions in the context of the relevant literature. A broad consensus emerged that the time was now ripe for launching such studies, and several common themes were identified--most notably the considerable efficiency gains of multistage sampling design, specifically those made by testing only a portion of the subjects with a high-density genomewide technology, followed by testing additional subjects and/or additional SNPs at regions identified by this initial scan.     

Recent developments in selenium metabolism and chemical speciation: a review.

The biological roles of selenium and its mode of action have only recently begun to be revealed. To date, the major functions of selenium can be attributed to its antioxidative properties and its role in the regulation of thyroid hormone metabolism, cell growth and eicosanoid biosynthesis. The unusual feature of selenoprotein synthesis is that selenocysteine insertion is specified by the stop UGA codon. A number of selenocysteine-specific gene products and a stem-loop structure in the 3' untranslated region are required for selenocysteine biosynthesis and the decoding of UGA codons in the open reading frame of the mRNA. The major biological functions of selenium are achieved through its redox activity when present as selenocysteine at the active sites of selenoproteins and these proteins are selenium-dependent since replacement with the sulphur analogue cysteine causes loss of enzyme activity. Both organic and inorganic forms of selenium may be utilised by the body, with the selenoamino acids showing greatest bioavailability. Knowledge of the biochemistry of the element coupled with appropriate techniques for the study of the distribution of selenium species in health and disease could help to identify sensitive markers of selenium status.     

Large gryphaeid oysters as habitats for numerous sclerobionts: a case study from the northern Red Sea

The shell of a living specimen of the Indo-Pacific gryphaeid giant oyster Hyotissa hyotis was colonized by numerous encrusting, boring, nestling and baffling taxa which show characteristic distribution patterns. On the upper valve, sponge-induced bioerosion predominates. On the lower valve intergrowth of chamid bivalves and thick encrusting associations—consisting mostly of squamariacean and corallinacean red algae, acervulinid foraminifera, and scleractinian corals—provides numerous microhabitats for nestling arcid and mytilid bivalves as well as for encrusting bryozoans and serpulids. Such differences between exposed and cryptic surfaces are typical for many marine hard substrata and result from the long-term stable position of the oyster on the seafloor. The cryptic habitats support a species assemblage of crustose algae and foraminifera that, on exposed surfaces, would occur in much deeper water.     

Recent developments in the study of human biology in China: a review.

The systematic study of human variation in China has only recently begun. Over the last decade extensive data have been collected that document the distribution of dermatoglyphic parameters, genetic markers, and anthropometric measurements in both majority Han and diverse minority populations of China. Here, I review recent syntheses of these studies made by Chinese investigators. These syntheses demonstrate the role that the study of human biological variation can play in reconstructing the population history of a vast and complex demographic unit such as China.     

Methods for isolation and confirmation of Vibrio vulnificus from oysters and environmental sources: a review

The gram-negative bacterium Vibrio vulnificus is a natural inhabitant of estuarine waters and poses a significant health threat to humans who suffer from immune disorders, liver disease, or hemochromatosis (iron overload). V. vulnificus enters human hosts via wound infections or consumption of raw shellfish (primarily oysters), and infections frequently progress to septicemia and death in susceptible individuals. Prevalence in waters and shellfish is not correlated with fecal indicator organisms; therefore, species-specific detection and enumeration of V. vulnificus in the environment has become a priority for agencies that are responsible for shellfish safety. The many selective-differential media developed for isolation of Vibrio spp., and specifically for V. vulnificus detection, are reviewed here; however, none of the media developed to date combines the sensitivity to low numbers with the specificity necessary to inhibit growth of other organisms. Therefore, immunological and molecular protocols are needed for confirmation of the identity of the organism and are discussed in detail. Methods under development that hold promise for rapid, accurate, and sensitive detection and enumeration of the organism include multiplex and real-time PCR. Developing technologies that have proven useful for detection and investigation of other pathogens such as biosensors, spectroscopy and microarrays may provide the next generation of tools for investigation of the prevalence and ecology of V. vulnificus.     

Recent developments on triazole nucleus in anticonvulsant compounds: a review

Epilepsy is one of the common diseases seriously threatening life and health of human. More than 50 million people are suffering from this condition and anticonvulsant agents are the main treatment. However, side effects and intolerance, and a lack of efficacy limit the application of the current anticonvulsant agents. The search for new anticonvulsant agents with higher efficacy and lower toxicity continues to be the focus and task in medicinal chemistry. Numbers of triazole derivatives as clinical drugs or candidates have been frequently employed for the treatment of various types of diseases, which have proved the importance of this heterocyclic nucleus in drug design and discovery. Recently many endeavours were made to involve the triazole into the anticonvulsants design, which have brought lots of active compounds. This work is an attempt to systematically review the research of triazole derivatives in the design and development of anticonvulsant agents during the past two decades.