异常气候条件下秘鲁外海茎柔鱼栖息地的时空变动

Spatio-temporal variations in the habitat of jumbo squid Dosidicus gigas in the Southeast Pacific Ocean off Peru under anomalous climate conditions

茎柔鱼主要分布于东太平洋,是我国鱿钓渔船的主要捕捞对象,气候变化对其栖息地有较大影响。本研究依据1950−2015年海表温度(SST)、海表高度距平(SSHA)以及尼诺指数(Niño3.4指数),计算秘鲁外海茎柔鱼栖息地适宜性指数(HSI),分析在厄尔尼诺(El Niño)、正常气候和拉尼娜(La Niña)条件下适宜栖息地的时空变动。分析表明,海表温度距平(SSTA)和SSHA与Niño3.4指数的变化趋势基本相同,Niño3.4指数与SSTA和SSHA均呈显著正相关,但与HSI值呈显著负相关。依据气候事件的定义,将研究年份划分为El Niño年,正常年和La Niña年。研究发现,在El Niño年,茎柔鱼渔场水温变暖,海面高度上升,适宜的SST和SSHA范围缩小,导致适宜的栖息地面积范围缩减;而在正常气候和La Niña年份,茎柔鱼渔场水温变冷,海面高度下降,适宜的SST和SSHA范围增大,因此适宜的栖息地面积范围增加。此外,Niño3.4指数和茎柔鱼渔场HSI纬度重心呈显著正相关,在El Niño事件下适宜的栖息地纬度重心向南偏移。研究认为,不同ENSO事件下茎柔鱼渔场环境变化显著,进而影响茎柔鱼适宜的栖息地范围及其空间分布。

Jumbo squid Dosidicus gigas is the main fishing target by Chinese squid-jigging fisheries,which mainly distributes in the eastern Pacific Ocean.Its habitat can be greatly affected by climatic changes.In this study,we calculated the habitat suitability index(HSI)on the squid fishing ground in the Southeast Pacific Ocean off Peru based on data of sea surface temperature(SST),the anomalies of sea surface height(SSHA)and Niño3.4 index during 1950 to 2015.Spatio-temporal variations in the squid habitat were further examined under the El Niño,the normal and the La Niña conditions.The results showed that variations in SST anomalies(SSTA)and SSHA in the fishing ground were consistent with those of the Niño3.4 index.Cross correlation analysis indicated that both SSTA and SSHA were significantly positively correlated with the Niño3.4 index.However,the HSI values were significantly negatively correlated with the Niño3.4 index.We divided the years between 1950 and 2015 into three types,the El Niño years,the normal years and the La Niña years.During the El Niño years,water temperature became warm,and the SSH increased;these changes led to contracted areas of suitable SST and SSHA,therefore,the range of suitable habitats largely decreased.However,during the normal and the La Niña years,water temperature was cold,the SSH decreased,and ranges of suitable SST and SSHA enlarged;these changes resulted in the increases in suitable habitat for the squid.Furthermore,the latitudinal gravity centers of suitable HSI on the squid fishing ground were significantly positively correlated with the Niño3.4 index.The latitudinal gravity centers of suitable HSI shifted southward in the El Niño years.Our findings suggested that ENSO events significantly affected environmental conditions on the squid fishing ground,and thus affected ranges and latitudinal distribution of suitable habitat for the squid in the Southeast Pacific Ocean off Peru.