Histopathological biomarkers in estuarine fish species for the assessment of biological effects of contaminants

The increasing emphasis on the assessment and monitoring of estuarine ecosystems has highlighted the need to deploy appropriate biological indices for these locations. Fish diseases and histopathology, with a broad range of causes, are increasingly being used as indicators of environmental stress since they provide a definite biological end-point of historical exposure. This study reports on the histopathological alterations observed in selected organs and tissues of three species of estuarine fish (Platichthys flesus, Pomatoschistus minutus and Zoarces viviparus), captured from four British estuaries (the Tyne, Tees, Mersey and Alde), differently impacted by contaminants, including PAHs. A biannual sampling regime was used to identify the important seasonal variations that occur in terms of the observed biological effects. Inflammatory lesions and hepatocellular fibrillar inclusions attained their highest prevalence in P. flesus captured from the Tyne, Tees and Mersey. The presence of pre-neoplastic and neoplastic toxicopathic lesions was highest in P. flesus captured from these sites, when compared to fish from the Aide reference site. In particular, the prevalence of hepatic foci of cellular alteration (up to 43.3%) and hepatocellular adenoma (up to 10%) were highest in P. flesus captured from the Mersey estuary. Intersex (ovotestis) was only recorded in male P.flesus captured from the Mersey estuary (up to 8.3%) and from male Z. viviparous captured from the Tyne estuary (25%). Pathologies associated with the gill and the kidney were also most prevalent in fish captured from the Tyne, Tees and Mersey estuaries. This study has successfully applied histopathology to an estuarine monitoring program, both for the recording of toxicopathic lesions in the liver and other organs, and for the detection of the endpoint of endocrine disruption, intersex. As such, it provides a powerful integrative tool for the assessment of biological effects of contaminants in these environments.     

Physical and anthropogenic effects on observed long-term nutrient changes in the Irish Sea

The trend in Irish Sea nutrient concentrations over the last four decades has been considered to reflect changes in anthropogenic loading. Comparison of a long-term database for the Menai Strait, North Wales, with an established historic data set for the Cypris station, Isle of Man, indicates that climate also has a significant influence on observations of nutrient concentrations. Data are presented detailing long-term shifts in nitrate, phosphate and silicate measurements since the 1960s at these two fixed sampling sites in the Irish Sea. Broad systematic changes observed in all three nutrients over the decades show a rise from the 1960s through to the 1980s, followed generally by an overall decline in the 1990s. Decadal-scale salinity changes occur in the opposite sense to nutrient changes. Anthropogenic inputs from freshwater cannot fully account for observed nutrient trends, neither is there evidence for shifts in nutrient concentrations in oceanic waters over the past four decades. Climatically forced movement in the geographical position of the freshwater/seawater mixing zone over a decadal time scale could, however, give rise to the observed shifts in nutrient concentration and salinity. This cannot alter nutrient concentration and salinity per se, but causes the measurements taken at fixed sampling sites to fluctuate inversely over this time scale. It is concluded that there is complex interplay between anthropogenic loading and climate affecting the distribution of nutrients in the Irish Sea.     

Dynamics and control of a towed underwater vehicle system, part I: model development

Autonomous vehicles are being developed to replace the conventional, manned surface vehicles that tow mine hunting towed platforms. While a wide body of work exists that describes numerical models of towed systems, they usually include relatively simple models of the towed bodies and neglect the dynamics of the towing vehicle. For systems in which the mass of the towing vehicle is comparable to that of the towed vehicle, it becomes important to consider the dynamics of both vehicles. In this work, we describe the development of a numerical model that accurately captures the dynamics of these new mine hunting systems. We use a lumped mass approximation for the towcable and couple this model to non-linear numerical models of an autonomous surface vehicle and an actively controlled towfish. Within the dynamics models of the two vehicles, we include non-linear controllers to allow accurate maneuvering of the towed system.     

Characterization of Estuarine Marine Clays for Coastal Reclamation in Pusan, Korea

Large scale reclamation works in coastal areas of the Nakdong River plain are at various stages of progress, since early 1990's on in-situ soft marine clay deposits. These deposits are of the order of 30 to 40 m thick. A realistic rapid characterization of soft ground would ensure success of any reclamation work in this area. In order to cope with the work carried out with different agencies, it is desirable to evolve a systematic methodology. In this study, engineering properties of clays at three coastal areas, Gadukdo, Noksan and Shinho, have been generated. The analysis of data has been done within the framework of classical developments in soil mechanics. Analysis has also been made by making use of the recent developments in dealing with soft clays. The dominant factors, namely, stress, time, and environment influencing the response of clay to loading are identified.     

Changes in the hydrography of Central California waters associated with the 1997–98 El Niño

Oceanographic conditions off Central California were monitored by means of a series of 13 hydrographic cruises between February 1997 and January 1999, which measured water properties along an oceanographic section perpendicular to the California Coast. The 1997–98 El Niño event was defined by higher than normal sea levels at Monterey, which began in June 1997, peaked in November 1997, and returned to normal in March 1998. The warming took place in two distinct periods. During June and July 1997, the sea level increased as a result of stronger than normal coastal warming below 200 dbars and within 100 km of the coast, which was associated with poleward flow of saltier waters. During this period, deeper (400–1000 dbar) waters between 150–200 km from shore were also warmed and became more saline. Subsequently, sea level continued to rise through January 1998, mostly as a result of the warming above 200 dbars although, after a brief period of cooling in September 1997, waters below 200 dbar were also warmer than normal during this period. This winter warm anomaly was also coastally trapped, extending 200 km from shore and was accompanied by cooler and fresher water in the offshore California current. In March and April 1998, sea level dropped quickly to normal levels and inshore waters were fresher and warmer than the previous spring and flowed southward.The warming was consistent with equatorial forcing of Central California waters via propagation of Kelvin or coastally-trapped waves. The observed change in heat content associated with the 1997–98 El Niño was the same as that observed during the previous seasonal cycle. The warming and freshening events were similar to events observed during the 1957–58 and 1982–83 El Niños.     

Effect of ice cover on oscillations of fluid in a closed basin

Within the framework of the linear theory of long waves, the problem of the effect of ice cover on seiche oscillations of fluid in a two-dimensional constant-depth basin is solved. The eigenfrequencies and eigenfunctions of seiche oscillations are obtained for different boundary conditions at ice edges: rigid coupling and free edges. The forced oscillations of fluid and ice under the action of a moving disturbance of atmospheric pressure are investigated. The change in the stress of ice bending is considered and it is shown that the coast ice can be broken.     

Variations in the sedimentation in Kara Bogaz Gol Bay related to sea level fluctuations during the Novocaspian time

The structure of the bottom sediments in Kara Bogaz Gol Bay is correlated with the history of the sea level fluctuations in the Caspian Sea during the Novocaspian time based on the radiocarbon geochronology of the coastal and bottom sediments. Instrumental observations of the sea level and the hydrochemical regime of the bay are considered to substantiate the correlations obtained.     

Volcanogenic complexes of the Sea of Okhotsk and the Sea of Japan (Comparative analysis)

Several coeval volcanogenic complexes indicating synchronous volcanic events in the Sea of Japan and the Sea of Okhotsk are defined. Volcanics from different-age complexes of the Sea of Okhotsk show many features in common and are attributed to the Pacific type of calc-alkaline series. They were formed in geodynamic settings of the active continental margin and point to its origination on the continental crust of the fragmented Asian continent margin. The volcanic rocks developed in the Sea of Japan reflect different rifting stages. The initial stage was marked by an eruption of calc-alkaline lavas (Paleocene-Eocene complex). At the stage of the marginal-sea spreading, erupted volcanics of the middle Miocene-Pliocene complex were melted from the depleted mantle and magmatism terminated by an eruption of postspreading Pliocene-Holocene volcanics melted from the enriched mantle EM I. Along with the differences, the magmatism in the Sea of Japan and Sea of Okhotsk has some features in common. In both cases, the sialic component of the lithosphere substantially influenced the magma generation.