Organochlorines are found even in organisms living in remote areas such as the Arctic marginal ice zone. Organochlorine concentrations in ice-associated (sympagic) amphipods are related to their diet. Therefore, the size-dependent diet shift of Gammarus wilkitzkii may influence its organochlorine content. In this preliminary study, the organochlorine concentrations in two size classes (small 29 mm and large >29 mm) of G. wilkitzkii were analysed. The concentrations of more lipophilic compounds [e.g. polychlorinated biphenyls (PCBs)] were lower in the small than the large size class, whereas concentrations of less lipophilic compounds [e.g. hexachlorocyclohexanes (HCHs)] did not differ by size class.
Since contamination transport by the atmosphere, ocean currents and sea ice may vary, the organochlorine burden in sympagic organisms may also vary. There are no data available on temporal variation of organochlorine burden in Arctic sympagic fauna. Therefore, we compared organochlorine concentrations in sympagic amphipods (G. wilkitzkii, Apherusa glacialis and Onisimus spp.) between 1998 and 1999. Organochlorine concentrations in all amphipods were low in both years, with sum organochlorines from 50.7 to 621.9 ng g−1 lipid weight. The concentrations of hexachlorobenzene (HCB), chlordanes, DDTs and PCBs were higher in 1999 than 1998, whereas the HCH concentrations were lower in 1999 than 1998. The organochlorine concentrations differed between the taxa in both years in a similar increasing manner from A. glacialis to both G. wilkitzkii and Onisimus spp.
In studies of bioaccumulation relative to body size and temporal variation, a thorough interpretation requires samples from several size classes and years. Nevertheless, the present data provide new knowledge on contaminants in Arctic invertebrates where data are scarce. 相似文献
The Iberian wild goat (Capra pyrenaica), an endemic species to the Iberian Peninsula, was represented in the past by four subspecies. Currently, the conservation status of the recognized subspecies - C. p. hispanica and C. p. victoriae - is quite different, being the former broadly distributed while the latter inhabits fewer and smaller areas. In this global context, our specific aims were to assess the biogeographical relationships, similarities and differences between the Iberian wild goat subspecies, and to evaluate their conservation status from a biogeographical perspective. We modelled the ecogeographical favourability for each subspecies, and also for the whole species, and we comparatively analyzed the spatial relationships among models in order to detect differential biogeographical patterns. Our results showed a differential pattern for each Iberian wild goat subspecies, and thus each one should be independently considered when designing management strategies. The distribution of C. p. victoriae was closely related to climatic conditions, thus it is highly sensitive to variations in climatic characteristics. Finally, from the perspective of metapopulation theory, and according to the geographical structure of their favourable areas, C. p. victoriae is at higher risk than C. p. hispanica. We discuss the implications of our results for species/subspecies conservation, and highlight the importance of conservation biogeography. 相似文献
The variability in surface water chemistry within and between aquatic ecosystems is regulated by many factors operating at
several spatial and temporal scales. The importance of geographic, regional-, and local-scale factors as drivers of the natural
variability of three water chemistry variables representing buffering capacity and the importance of weathering (acid neutralizing
capacity, ANC), nutrient concentration (total phosphorus, TP), and importance of allochthonous inputs (total organic carbon,
TOC) were studied in boreal streams and lakes using a method of variance decomposition. Partial redundancy analysis (pRDA)
of ANC, TP, and TOC and 38 environmental variables in 361 lakes and 390 streams showed the importance of the interaction between
geographic position and regional-scale variables. Geographic position and regional-scale factors combined explained 15.3%
(streams) and 10.6% (lakes) of the variation in ANC, TP, and TOC. The unique variance explained by geographic, regional, and
local-scale variables alone was <10%. The largest amount of variance was explained by the pure effect of regional-scale variables
(9.9% for streams and 7.8% for lakes), followed by local-scale variables (2.9% and 5.8%) and geographic position (1.8% and
3.7%). The combined effect of geographic position, regional-, and local-scale variables accounted for between 30.3% (lakes)
and 39.9% (streams) of the variance in surface water chemistry. These findings lend support to the conjecture that lakes and
streams are intimately linked to their catchments and have important implications regarding conservation and restoration (management)
endeavors. 相似文献