نتایج جستجو برای: pelagic
تعداد نتایج: 5978 فیلتر نتایج به سال:
Lakes of the Tibetan Plateau lack direct anthropogenic influences, providing pristine high-altitude (> 4000 m) sites to study microbial community structure. We collected samples from the pelagic, littoral, and riverine zones of Lake Bangongco, located on the western side of the Plateau, to characterize bacterial community composition and geochemistry in three distinct, but hydrologically connec...
Prey preference of top predators and energy flow across habitat boundaries are of fundamental importance for structure and function of aquatic and terrestrial ecosystems, as they may have strong effects on production, species diversity, and food-web stability. In lakes, littoral and pelagic food-web compartments are typically coupled and controlled by generalist fish top predators. However, the...
1. Using a palaeolimnological approach in shallow lakes, we quantified the species richness responses of diatoms and Cladocera to phosphorus enrichment. We also examined differences in species richness responses between littoral and pelagic assemblages of our focal communities. To address both spatial and temporal relationships, our study includes an analysis of both surface sediments from 40 l...
It is generally considered that nitrogen availability is one of the major factors regulating primary production in temperate coastal marine environments. Coastal regions often receive large anthropogenic inputs of nitrogen that cause eutrophication. The impact of these nitrogen additions has a profound effect in estuaries and coastal lagoons where water exchange is limited. Such increased nutri...
There is now a general agreement that sharks, and pelagic sharks in particular, are facing widespread declines in population level due to fishing activity (Pauly et al., 2003). Recent studies suggest dramatic reductions in relative abundance of up to 80% have occurred in as little as 15 years for some species (Baum et al., 2003; Myers et al., 2006), trends most likely linked to greater target c...
Stable isotopes (!13C and !15N) were used to examine the origin of organic matter for the most representative demersal species of the SW Icelandic Wshery, accounting for over 70% of landings of those species in the North Atlantic. Samples were collected during a 2-week period in early September 2004 from landings and directly during Wshing cruises. Stable isotopes showed that particulate organi...
Major climatic changes in the Pleistocene had significant effects on marine organisms and the environments in which they lived. The presence of divergent patterns of demographic history even among phylogenetically closely-related species sharing climatic changes raises questions as to the respective influence of species-specific traits on population structure. In this work we tested whether the...
Using remote sensing of sea surface temperature (SST), sea surface height anomaly (SSHA) and chlorophyll-a (Chl-a) together with catch data, we investigated the detection and persistence of important pelagic habitat hotspots for skipjack tuna in the Gulf of Bone-Flores Sea, Indonesia. We analyzed the data for the period between the northwest and southeast monsoon 2007-2011. A pelagic hotspot in...
Selenium and Mercury Interactions in Apex Predators from the Gulf of Trieste (Northern Adriatic Sea)
Since the environmental levels of selenium (Se) can moderate the bioaccumulation and toxicity of mercury (Hg) in marine organisms, their interactions were studied in seawater, sediments, plankton and the benthic (Bull ray Pteromylaeus bovinus, Eagle ray Myliobatis aquila) and the pelagic (Pelagic stingray Dasyiatis violacea) rays, as apex predators in the Gulf of Trieste (Northern Adriatic Sea)...
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