Global Ecology and Conservation (Apr 2023)
Spatial variability of striped bass spawning responses to climate change
Abstract
Diverse responses of life history process phenology to global climate changes have been reported across a range of taxa. Species exhibiting partial migration behaviors with multiple contingents, often aggregated by size or development stage, undertake different spawning migrations to complete their life cycles. Therefore, the effects of climate on the spawning phenology of multiple spawning contingents could have spatio-temporal differences in a large ecosystem. Multiple spawning contingents have been reported for striped bass (Morone saxatilis) in the Hudson River Estuary (HRE), originating from two known spawning grounds which are geographically separated by about 90 km. To evaluate if there is variability between spawning grounds in the response of spawning phenology to climate change, we examined ichthyoplankton data collected by the Hudson River Biological Monitoring Program (HRBMP) from 1974 to 2017. This study suggests that both onset and cessation times of spawning season of two spawning grounds (upper and lower) occurred earlier in recent years. However, the annual variation and rates of change were greater for the upper river spawning ground. Gradient forest analyses indicated that water temperature had the most influence on spawning phenology while the roles of thermal metrics varied between the two spawning grounds. Our study suggests that the upper spawning habitat for striped bass in the HRE was more vulnerable to climate changes compared to the lower spawning ground. Using striped bass as a model species, our work highlights the possibilities that the response of phenology changes to climate for a single population are not always homogeneous over the entire species distribution. A finer scale evaluation of fish responses to climate-induced environmental variability is needed to better understand fish adaptive capacity. This study also highlights the importance of long-term monitoring programs in evaluating climatic impacts on fish life history processes.
