Response of North Atlantic Zooplankton Populations to Environmental Forcing

Zooplankton, the charismatic microfauna in the oceans, make up the base of the ecosystem along with microbes and phytoplankton.  They occur in a myriad of shapes and sizes and consist of both holozooplankton (animals that spend their entire life in the ocean’s water column) and merozooplankton (larval stages of species that live as adults on the seafloor). They are broadly distributed in biogeographic provinces with unique physical, chemical, and biological properties. In the North Atlantic Ocean, as well as other ocean basins, zooplankton diversity, biogeography, and phenology are responsive to environmental variation associated with changes in natural climatic factors and anthropogenic forcing. Natural forcing includes fluctuations in solar energy, volcanic eruptions, and decadal to millennial scale internal oscillatory climate variation. In contrast to natural oscillations, human activities (especially greenhouse gas emissions) often appear to drive the ocean system in a unidirectional manner. Environmental time-series and spatial monitoring data are essential to observe and understand these changes in marine zooplankton populations over seasonal, interannual, decadal, and longer time scales. The extent and direction of responses varies from site to site, and driving forces and climate change effects varies among regions. The length of time-series observations also affects the result: short time-series may give biased results. Since many zooplankton species occur across the North Atlantic Basin, determining the correlation length scales of population fluctuations, discriminating between local and remote forcings, and understanding the underlying mechanisms require a basin-scale approach.  The oceans are warming and becoming more acidic, and many coastal regions are becoming more eutrophic due to nutrients entering the marine system.  Zooplankton are sentinels of change throughout the North Atlantic Ocean and substantial changes have occurred in their distribution and abundance across the North Atlantic in the past 50+ years. This talk will highlight some of these changes and describe the data needed in the future to better predict ecosystem change to be expected in the next decades as we continue to alter our climate.