加拿大科研人員在新一期《自然—通信》（Nature Communications）雜志上報(bào)告說，由于氣候變暖導(dǎo)致北極海冰面積逐漸縮減,，生活在加拿大哈得孫灣的北極熊生育率正在下降,。
哈得孫灣是位于加拿大東北部的一個(gè)大型海灣，位于北冰洋邊緣,，是北極熊的重要棲息地,。加拿大艾伯塔大學(xué)的科研人員分析了哈得孫灣上世紀(jì)90年代以來冰層縮減的情況，并將所獲得的數(shù)據(jù)與北極熊的數(shù)量進(jìn)行對比,。
海冰是北極熊覓食和生活的重要平臺(tái)，也是雌性北極熊懷孕時(shí)的休養(yǎng)生息之地,。研究發(fā)現(xiàn),，海冰如果融化過早，北極熊捕食海豹的難度就會(huì)增加,，導(dǎo)致能量積蓄不足,，難以生育。
模擬推算顯示,，如果哈得孫灣海冰每年融化的時(shí)間比上世紀(jì)90年代提前1個(gè)月,，就會(huì)有40%至73%的懷孕雌性北極熊無法成功生育；如果海冰融化時(shí)間提前兩個(gè)月,，這一比例會(huì)達(dá)到55%到100%,。
在過去10年里，哈得孫灣北極熊的數(shù)量已由1200頭下降至目前的約900頭,。研究人員指出,，如果北極海冰面積縮減的趨勢持續(xù)下去，不僅哈得孫灣的北極熊將減少,，整個(gè)北極地區(qū)的北極熊也將面臨一場生存危機(jī),。（生物谷Bioon.com）
生物谷推薦原文出處：
Nature Communications doi:10.1038/ncomms1183
Predicting climate change impacts on polar bear litter size
Péter K. Molnár,1, 2, 4 Andrew E. Derocher,2 Tin Klanjscek3 & Mark A. Lewis1, 2
Predicting the ecological impacts of climate warming is critical for species conservation. Incorporating future warming into population models, however, is challenging because reproduction and survival cannot be measured for yet unobserved environmental conditions. In this study, we use mechanistic energy budget models and data obtainable under current conditions to predict polar bear litter size under future conditions. In western Hudson Bay, we predict climate warming-induced litter size declines that jeopardize population viability: ~28% of pregnant females failed to reproduce for energetic reasons during the early 1990s, but 40–73% could fail if spring sea ice break-up occurs 1 month earlier than during the 1990s, and 55–100% if break-up occurs 2 months earlier. Simultaneously, mean litter size would decrease by 22–67% and 44–100%, respectively. The expected timeline for these declines varies with climate-model-specific sea ice predictions. Similar litter size declines may occur in over one-third of the global polar bear population.
