印度洋中西部和大西洋西部水域大眼金枪鱼的食性比较

根据2004年8月至2005年3月大西洋西部水域及2003年12月份至2004年5月份在印度洋中西部水域金枪鱼延绳钓渔业所获取的大眼金枪鱼数据,对两个诃查区域内的大眼金枪鱼食性进行了研究。结果表明,印度洋中西部水域大眼金枪鱼的食物组成包括沙丁鱼、鱿鱼、乌贼等13个饵料类群,其中主要摄食鱿鱼和沙丁鱼;大西洋西部水域大眼金枪鱼主要摄食沙丁鱼、鱿鱼、虾类等13种饵料类群,主要以沙丁鱼为饵,其次为鱿鱼。印度洋中西部水域大眼金枪鱼空胃率非常高,基本上维持在60％以上;大西洋西部水域大眼金枪鱼空胃率相对较低,基本上都在30％以下。印度洋中西部水域大眼金枪鱼平均饱满指数变化不大,基本上维持在0．40～0．55之间。大西洋西部水域大眼金枪鱼平均饱满指数变化也不太大。印度洋中西部水域大眼金枪鱼各月平均饱满指数高于大西洋西部水域,且各月空胃率高于后者。印度洋中西部和大西洋西部水域大眼金枪鱼Shannon-Weiner多样性指数H’基本上都1．50～2．00之间变化。相同调查月份内,印度洋中西部水域大眼金枪鱼食物Pielou均匀度指数J’均高于大西洋西部水域。     

Seasonal prevalence and intensity of follicular atresia in Baltic cod Gadus morhua callarias L.

In the present study, 307 ovaries of eastern Baltic cod Gadus morhua callarias sampled during the prespawning and spawning season 2000 were analysed histologically to estimate the seasonal prevalence and intensity of atresia. The number of atretic oocytes per ovary was estimated using a combination of the physical disector method and volume fraction (Delesse principle). Atretic oocytes were observed in 32% of the ovaries. Prevalence of atresia was independent of female size, but increased significantly with declining female condition from prespawning and through the spawning stages. The relative intensity of atresia, i.e. number of atretic oocytes in relation to normally developed vitellogenic oocytes, was low amounting to 1·4% on average. Similar to prevalence, relative intensity of atresia differed significantly between maturity stages and increased with decreasing female condition. The population egg loss due to atresia amounted to 4·6% indicating that Baltic cod was performing close to maximum productivity, i.e. potential egg production.     

SPATIOTEMPORAL PREDICTION MODELS OF CETACEAN HABITATS IN THE MID-WESTERN NORTH ATLANTIC OCEAN (FROM CAPE HATTERAS, NORTH CAROLINA, U.S.A. TO NOVA SCOTIA, CANADA)

Habitat prediction models were developed for 13 cetacean species of the mid-western North Atlantic Ocean: beaked whale, fin whale, humpback whale, minke whale, pilot whale, sperm whale, bottlenose dolphin, common dolphin, Risso's dolphin, spotted dolphin, whitesided dolphin, and harbor porpoise. Using the multiple logistic regression, sightings of cetaceans during the 1990–1996 summer (June-September) surveys were modeled with oceanographic (sea surface temperature, monthly probability of front occurrence) and topographic (depth, slope) variables for the same period. Predicted habitat maps for June and August were created for each species using a Geographical Information System. The predicted habitat locations matched with current and historic cetacean sighting locations. The model also predicted habitat shifts for some species associated with oceanographic changes. The correct classification rate of the prediction models with 1997–1998 summer survey data ranged from 44% to 70%, of which most of the misclassifications were caused by false positives ( i.e. , absence of sightings at locations where the models predicted).     

Localisation of Ig heavy chain mRNA positive cells in Atlantic cod (Gadus morhuaL.) tissues; identified byin situhybridisation

Localisation of immunoglobulin heavy chain (IgH) producing cells was determined in sections from head kidney, spleen, thymus, gills, gut, skin, heart and liver from the Atlantic cod. In general, IgH mRNA positive cells were detected in all organs examined and were mainly located to the connective tissue surrounding the vascular system in these organs. In the head kidney and spleen, IgH mRNA positive cells appeared as single distributed cells or as dense clusters, whereas in the thymus only single distributed positive cells were observed. The percentage of Ig heavy chain mRNA positive (plasma) cells in the head kidney, spleen and thymus was estimated at about 1% of the total cell mass. The number of IgH mRNA positive cells was lower than this in all the other organs examined.     

Duration of synchronous cleavage cycles and rate of development at different temperatures in the Baltic herring

The duration of one synchronous cleavage cycle (τ₀) in Clupea harengus membras at different temperatures ( T ) was given by: (logτ₀)= 2.4349–0–0684T for T= 0.9–13°C, and (logτ₀)= 1.61010–oooit for t= 13–18–7°C.     

Immunomic Identification of Malaria Antigens Associated With Protection in Mice

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Highlights

• •Production of sera with different levels of protection against rodent Plasmodium.
• •Generation of immunomic and proteomic data sets enriched in protective antigens.
• •Prediction of the most likely protective antigens using a weighted scoring system.

     

Distribution Patterns of Isomorphic Cold-Water Dinoflagellates (Scrippsiella/Woloszynskia Complex) Causing ‘red tides’ in the Baltic Sea

During the latest years medium-sized (15–30 μm), single-celled dinoflagellates have been reported to form blooms in the northern Baltic Proper and the Gulf of Finland in winter and spring. Recent studies (Kremp et al., 2003. Proceedings of the 7th International conference of Modern and Fossil Dinoflagellates, September 21–25, Nagasaki, Japan, 66 pp.) indicate that those blooms are caused by two isomorphic species – Scrippsiella hangoei (Schiller) Larsen, and a new species, tentatively belonging to the genus Woloszynskia. Until now there has been no report on how widely distributed these phytoplankton species are in the Baltic Sea. In this study, the occurrence of Scrippsiella/Woloszynskia complex in the entire Baltic Sea was investigated, by using monitoring data from 1997 to 2003. The species occurred in a salinity range from 2 to 8 PSU. Highest concentrations were observed at salinity 4.5–6.5 PSU. Maximum cell densities of Scrippsiella/Woloszynskia complex in the water column were mainly obtained in April or in the beginning of May by the water temperature <3 °C prior to stratification was formed. In the central Gulf of Finland, the second maximum was found in 1999 and 2002 by the temperature >6 °C. Bloom formations in the Baltic Proper and in the Gulf of Finland may not only be explained by optimum temperature and salinity, but also with other factors e.g. high nutrient concentrations and good seeding conditions from the sediments.     

Evaluating the performance of benthic multi-metric indices across broad-scale environmental gradients

The usefulness of benthic multi-metric indices when assessing seafloor integrity across broad environmental gradients should be deliberated, as their lack of transparency might hide important sources of variation and fail to identify environmental change. This study compares the performance of two multi-metric indices; the Benthic Quality Index (BQI) and the Brackish water Benthic Index (BBI) between three sub-basins in the Baltic Sea. Both indices reflect the salinity-driven gradient in macroinvertebrate diversity and composition as well as changes in bottom water oxygen concentrations. The relative contribution of predictor variables for explaining index variation does, however, differ between sub-basins, resulting in the indices representing different aspects of the benthic community along the environmental gradient. This context-dependency is caused by inherent differences in benthic community characteristics between the sub-basins of the Baltic Sea, and how the communities are portrayed by the indices. An increased transparency of the importance of the different predictors for directing index values is needed for coherent classifications over broad environmental gradients, such as those occurring in large estuarine water bodies. Use of a weight of evidence table to combine multiple indicators would preserve transparency and be more likely to provide a robust assessment method that would detect seafloor degradation at an early stage.