Dateset for : Ampelisca eschrichtii Krøyer, 1842 (Ampeliscidae) of the Sakhalin Shelf in the Okhotsk Sea starve in summer and feast in winter

Background. Ampelisca eschrichtii Krøyer, 1842 of the Sakhalin Shelf of the Okhotsk Sea, Far Eastern Russia, comprise the highest known biomass concentration of any amphipod population in the world and are a critically important prey source for western gray whales. Growth and reproduction in this population has not been apparent in summer. However, they are not accessible for sampling in winter to test a previous default conclusion that they grow and reproduce in winter. Methods. We tested the default winter growth and reproduction hypothesis by detailed comparisons of the brood and gonad development among 40 females and 14 males and brood sizes among females observed since 2002. Our test included six predictions of reproductive synchrony that would be apparent from gonad and brood morphology if active reproduction occurs in summer. Results. We found high prevalences of undersized and damaged oocytes, undersized broods, a lack of females brooding fully formed juveniles, atrophied ovaries, and males with mature sperm but lacking fully developed secondary sex morphologies required for pelagic mating. All of these conditions are consistent with trophic stress and starvation. Discussion. These A. eschrichtii populations therefore appear to starve in summer and to grow and reproduce in winter. The Offshore A. eschrichtii populations occur in summer below water strata bearing high phytoplankton biomasses. These populations are more likely to feed successfully in winter when storms mix phytoplankton to their depths.

背景：栖息于俄罗斯远东鄂霍次克海萨哈林陆架的埃氏安匹钩虾（Ampelisca eschrichtii Krøyer, 1842）是全球已知生物量浓度最高的端足类（Amphipoda）种群，同时也是西灰鲸极为关键的猎物来源。该种群的生长与繁殖在夏季并无明显观测迹象，但由于冬季无法对其开展采样，因此无法验证“该种群于冬季进行生长与繁殖”这一此前的默认结论。
方法：我们通过对40只雌性个体与14只雄性个体的抱卵发育与性腺发育情况，以及2002年以来观测到的雌性个体的抱卵量进行详细比对，来验证该默认的冬季生长繁殖假说。本次验证包含六项关于繁殖同步性的预测：若夏季存在活跃繁殖，则可通过性腺与育幼囊的形态学特征观测到该同步性。
结果：我们观测到大量个体存在卵母细胞尺寸偏小且受损、抱卵量不足、无携带完全成型幼体的雌性个体、卵巢萎缩，以及雄性个体虽具有成熟精子却缺乏远洋交配所需的完全发育第二性征。所有上述特征均与营养胁迫及饥饿状态相符。
讨论：因此，该埃氏安匹钩虾种群似乎在夏季处于饥饿状态，而于冬季开展生长与繁殖。夏季时，近海埃氏安匹钩虾种群栖息于浮游植物生物量较高的水层下方。当冬季风暴将浮游植物混合至其栖息深度时，这些种群更易成功获取食物。