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Distribution and abundance of western gray whales off northeastern Sakhalin Island, Russia, 2001’003
Meier SK Yazvenko SB Blokhin SA Wainwright P Maminov MK Yakovlev YM Newcomer MW 《Environmental monitoring and assessment》2007,134(1-3):107-136
In 2001–2003, >60,000 km of aerial surveys and 7,700 km of vessel surveys were conducted during June to November when critically
endangered Korean–Okhotsk or western gray whales (Eschrichtius robustus) were present off the northeast coast of Sakhalin Island, Russia. Results of surveys in all years indicated gray whales occurred
in predominantly two areas, (1) adjacent to Piltun Bay, and (2) offshore from Chayvo Bay, hereafter referred to as the Piltun
and offshore feeding areas. In the Piltun feeding area, the majority of whales were observed in waters shallower than 20 m
and were distributed from several hundred meters to ∼ 5 km from the shoreline. In the offshore feeding area during all years,
the distribution of gray whales extended from southwest to northeast in waters 30–65 m in depth. During all years, the distribution
and abundance of whales changed in both the Piltun and offshore feeding areas, and both north–south and inshore–offshore movements
were documented within and between feeding seasons. The discovery of a significant number of whales feeding in the offshore
area each year was a substantial finding of this study and raises questions regarding western gray whale abundance and population
levels, feeding behavior and ecology, and individual site-fidelity. Fluctuations in the number of whales observed within the
Piltun and offshore feeding areas and few sightings outside of these two areas indicate that gray whales move between the
Piltun and offshore feeding areas during their summer–fall feeding season. Seasonal shifts in the distribution and abundance
of gray whales between and within both the Piltun and offshore feeding areas are thought, in part, to be a response to seasonal
changes in the distribution and abundance of prey. However, the mechanism driving the movements of whales along the northeast
coast of Sakhalin Island is likely very complex and influenced by a multitude of factors.
*Deceased 相似文献
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Sujay S. Kaushal Paul M. Mayer Philippe G. Vidon Rose M. Smith Michael J. Pennino Tamara A. Newcomer Shuiwang Duan Claire Welty Kenneth T. Belt 《Journal of the American Water Resources Association》2014,50(3):585-614
Nonpoint source pollution from agriculture and urbanization is increasing globally at the same time climate extremes have increased in frequency and intensity. We review >200 studies of hydrologic and gaseous fluxes and show how the interaction between land use and climate variability alters magnitude and frequency of carbon, nutrient, and greenhouse gas pulses in watersheds. Agricultural and urban watersheds respond similarly to climate variability due to headwater alteration and loss of ecosystem services to buffer runoff and temperature changes. Organic carbon concentrations/exports increase and organic carbon quality changes with runoff. Nitrogen and phosphorus exports increase during floods (sometimes by an order of magnitude) and decrease during droughts. Relationships between annual runoff and nitrogen and phosphorus exports differ across land use. CH4 and N2O pulses in riparian zones/floodplains predominantly increase with: flooding, warming, low oxygen, nutrient enrichment, and organic carbon. CH4, N2O, and CO2 pulses in streams/rivers increase due to similar factors but effects of floods are less known compared to base flow/droughts. Emerging questions include: (1) What factors influence lag times of contaminant pulses in response to extreme events? (2) What drives resistance/resilience to hydrologic and gaseous pulses? We conclude with eight recommendations for managing watershed pulses in response to interactive effects of land use and climate change. 相似文献