典型气候事件对浙江近海底层鱼类时空分布的影响

气候变化对海洋生态系统产生多方面的影响,作为海洋生物中的主体,鱼类对气候变化的响应机制研究是探索典型气候事件对海洋生态系统影响的关键。根据2013-2022年浙江近海底拖网渔业资源调查数据,结合尼诺指数(Ocean Nino Index, ONI)、海表温度 (Sea Surface Temperature, SST)、海表温度距平 (Sea Surface Temperature Anomaly, SSTA)、叶绿素a浓度(Chlorophyll a, Chl-a)等海洋环境数据,采用小波函数、相关性分析等探究典型气候事件厄尔尼诺、拉尼娜对浙江近海底层鱼类生物量及其时空分布的影响。结果表明,浙江近海底层鱼类生物量与SST及Chl-a呈极显著正相关(P ＜ 0.01)。厄尔尼诺与拉尼娜发生时期春、秋季生物量均小于正常年份,正常年份及拉尼娜事件期间春季生物量具有显著性差异(P ＜ 0.05);正常年份及厄尔尼诺事件期间秋季生物量具有极显著性差异(P ＜ 0.01)。对ONI与海洋环境因子指数进行交叉小波发现,浙江近海SST、Chl-a对于典型气候事件均存在不同的频域同步及相关性:ONI与SST在时间局部存在2-3.9个月频域同步,SST滞后ONI3个月;ONI与 Chl-a存在1.7-3个月频域同步,Chl-a与ONI呈正相关;ONI与生物量存在3-3.6个月频域同步,生物量滞后于ONI3个月;ONI与SSTA在研究期间不存在明显的频域同步。春季,相较于正常年份,厄尔尼诺期间鱼类整体分布偏北;秋季厄尔尼诺发生期间鱼类整体向南移动,拉尼娜期间则向北移动。厄尔尼诺及拉尼娜事件不仅对鱼类群落在纬度上的分布产生影响,还会对鱼类向近岸洄游的快慢产生影响。两种典型气候事件通过影响浙江近海SST等环境进而对浙江近海底层鱼类时空分布产生影响。

Effects of typical climate events on spatio-temporal distribution of bottom fish in the coastal waters of Zhejiang

Climate change has various impacts on marine ecosystems. As the main body of marine life, the response of fish to climate change is a key factor in exploring the effects of typical climate events on marine ecosystems. Based on the 2013-2022 bottom trawl fishery resource survey data in the coastal waters of Zhejiang, by incorporating ocean environment data such as the Ocean Nino Index (ONI), Sea Surface Temperature (SST), Sea Surface Temperature Anomaly (SSTA), and Chlorophyll a (Chl-a), this study used wavelet functions and correlation analysis to explore the impact of typical climate events such as El Niño and La Niña on the biomass and spatio-temporal distribution of bottom fish in the coastal waters of Zhejiang. The results showed that the bottom-layer fish biomass in the coastal waters of Zhejiang was highly positively correlated with SST and Chl-a (P < 0.01). During the El Niño and La Niña periods, the biomass in the spring and autumn was lower than that in normal years. The biomass in the spring of normal years and La Niña events had significant differences (P < 0.05), and the biomass in the autumn of normal years and El Niño events had extremely significant differences (P < 0.01). The cross-wavelet analysis of ONI and ocean environmental factor indices found that the SST and Chl-a in the coastal waters of Zhejiang demonstrated different frequency domain synchronization and correlation with typical climate events: ONI and SST exhibited frequency domain synchronization with a temporal locality of 2-3.9 months. SST lagged behind ONI by 3 months. ONI and Chl-a exhibited frequency domain synchronization with a temporal locality of 1.7-3 months. Chl-a and ONI were positively correlated. ONI and biomass exhibited frequency domain synchronization with a temporal locality of 3-3.6 months. Biomass lagged behind ONI by 3 months. There was no evident frequency domain synchronization between ONI and SSTA during the research period. In the spring, compared with normal years, the overall distribution of fish during the El Niño period tended to be northward. During the El Niño period in autumn, the overall distribution of fish moved southward, but during the La Niña period, it moved northward. These two typical climate events not only affected the latitudinal distribution of fish communities but also affected the speed at which fish migrated closer to the shore. These typical climate events can affect the spatio-temporal distribution of bottom layer fish in the coastal waters of Zhejiang by affecting environmental factors such as SST.