Antarctic krill inhabit areas of the Southern Ocean that can exceed 4.0°C, yet they preferentially inhabit regions with temperatures of −1.5 to ≤1.5°C. Successful embryonic development and hatching are key to their life cycle, but despite the rapid climatic warming seen across their main spawning areas, the effects of elevated temperatures on embryogenesis, hatching success, and nauplii malformations are unknown. We incubated 24,483 krill embryos in two independent experiments to investigate the hypothesis that temperatures exceeding 1.5°C have a negative impact on hatching success and increase the numbers of malformed nauplii. Field experiments were on krill collected from near the northern, warm limit of their range and embryos incubated soon after capture, while laboratory experiments were on embryos from krill acclimated to laboratory conditions. The hatching success of embryo batches varied enormously, from 0 to 98% (mean 27%). Both field and laboratory experiments showed that hatching success decreased markedly above 3.0°C. Our field experiments also showed an approximate doubling of the percentage of malformed nauplii at elevated temperatures, reaching 50% at 5.0°C. At 3.0°C or below, however, temperature was not the main factor driving the large variation in embryo hatching success. Our observations of highly variable and often low success of hatching to healthy nauplii suggest that indices of reproductive potential of female krill relate poorly to the subsequent production of viable krill larvae and may help to explain spatial discrepancies between the distribution of the spawning stock and larval distribution.

中文翻译：

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南极磷虾的温度诱导孵化失败和无节幼体畸形

南极磷虾栖息在温度超过 4.0°C 的南大洋地区，但它们优先栖息在温度为 -1.5 至 1.5°C 的地区。成功的胚胎发育和孵化是它们生命周期的关键，但尽管它们的主要产卵区气候迅速变暖，但高温对胚胎发生、孵化成功和无节幼体畸形的影响尚不清楚。我们在两个独立实验中孵化了 24,483 只磷虾胚胎，以研究温度超过 1.5°C 会对孵化成功产生负面影响并增加畸形无节幼体数量的假设。田间实验是对从北部附近采集的磷虾、它们活动范围的温暖极限和捕获后不久孵化的胚胎进行的，而实验室实验是在适应实验室条件的磷虾胚胎上进行的。胚胎批次的孵化成功率差异很大，从 0 到 98%（平均 27%）。田间和实验室实验均表明，孵化成功率在 3.0°C 以上显着下降。我们的田间试验还表明，高温下畸形无节幼体的百分比大约翻了一番，在 5.0°C 时达到 50%。然而，在 3.0°C 或以下时，温度并不是导致胚胎孵化成功率差异很大的主要因素。