Stable oxygen isotope reconstruction of ambient temperature during the collapse of a cod (Gadus morhua) fishery
Stable oxygen isotope reconstruction of ambient temperature during the collapse of a cod (Gadus morhua) fishery
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DOI：
10.1890/07-2002.1
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发表时间：
2009-09-01
影响因子：
5
通讯作者：
Campana, Steven E.
中科院分区：
文献类型：
--
作者：
Jones, J. Brin;Campana, Steven E.
高开采背景下环境条件的变化可能会给商业捕捞的种群带来严重后果。加拿大东部附近的东斯科舍大陆架鳕鱼（Gadus morhua L.）的灭绝主要是由于过度捕捞，但也可能因大面积气温下降而加剧。最近的研究呼吁在排除环境条件作为崩溃因素之前准确确定环境温度（鱼的实际温度暴露历史）。我们利用耳石的稳定氧同位素组成 (delta O-18(oto)) 重建了东斯科舍大陆架鳕鱼从 1970 年到 2000 年的环境温度历史，以确定该种群是否经历了温度下降或改变了分布以避免温度下降。为了校正海水同位素含量 (delta O-w) 的 delta O-18(oto)，我们为东部斯科舍陆架的 delta O-18(w)（每密耳）和盐度（S，以 psu 为单位）之间的关系生成了一个新的元方程：delta O-18(w) = 0.539 x S - 18.790。环境温度序列显示，成熟鳕鱼的大范围地理分布在整个冷却时期保持不变，尽管它们的环境温度在温暖时期比预期低，在寒冷时期比预期温暖，表明小规模的温度调节运动。尽管平均水文温度为 4 摄氏度，但成熟鳕鱼通常栖息在最冷的水域（平均环境温度 = 3 摄氏度），而幼鱼通常栖息在较温暖的水域（平均环境温度 = 5.5 摄氏度）。年龄长度与环境温度显着相关，尤其是在生长的最初几年，因此环境温度的下降至少是渐近长度下降的部分原因（直到8岁）。最活跃的体温调节运动发生在温和变暖时期；因此，极端变暖事件（例如气候变化下预测的事件）可能会迫使这一历史上定居的种群发生大规模的纬度向北移动。在预测未来几年气候条件变化的情况下，追溯稳定同位素年表可以成为可持续管理战略的重要工具。
Changing environmental conditions set against a backdrop of high exploitation can result in severe consequences for commercially harvested stocks. The collapse of the Eastern Scotian Shelf cod (Gadus morhua L.) off eastern Canada was primarily due to overexploitation but may have been exacerbated by a widespread temperature decline. Recent studies have called for accurate determination of ambient temperature (the actual temperature exposure history of the fish) before discarding environmental conditions as a factor in the collapse. We used the stable oxygen isotope composition of otoliths (delta O-18(oto)) to reconstruct the ambient temperature history of Eastern Scotian Shelf cod from 1970 to 2000 in order to determine whether the stock experienced the temperature decline or shifted their distribution to avoid it. To correct delta O-18(oto) for seawater isotope content (delta O-w), we generated a new meta-equation for the relationship between delta O-18(w) (per mil) and salinity (S, in psu) on the Eastern Scotian Shelf: delta O-18(w) = 0.539 x S - 18.790. The ambient temperature series revealed that the large-scale geographic distribution of mature cod remained constant through the cooling period, although their ambient temperature was cooler than expected in warmer periods and warmer than expected in cooler periods, indicating small-scale thermoregulatory movement. Although the mean hydrographic temperature was 4 degrees C, mature cod usually inhabited the coldest available waters (mean ambient temperature = 3 degrees C), while the juveniles usually inhabited warmer waters (mean ambient temperature = 5.5 degrees C). Length-at-age was significantly related to ambient temperature, especially in the early years of growth, and therefore declining ambient temperatures were at least partially responsible for declines in asymptotic length (up to age 8 yr). The most active thermoregulatory movement occurred during a moderate warming period; therefore extreme warming events (such as those predicted under climate change) may force large-scale northward latitudinal shifts in this historically sedentary stock. Retroactive stable isotope chronologies can be an important tool in sustainable management strategies under the shifting climate conditions predicted for years to come.