U.S. GLOBEC: North Atlantic intercomparisons of interannual patterns in zooplankton species, in relation to climatic changes

Alessandra Conversi, Kenneth Sherman, Sultan Hameed

This project proposes to analyze together, for the first time, the two Continuous Plankton Recorder (CPR) multidecadal data collections from the British and US CPR programs. These data sets contain detailed taxonomic plankton information over large spatial (both sides of the Atlantic) and temporal (decades) scales. They were obtained using identical collection methods, the CPR samplers. The CPR sampling was based on monthly time intervals of:
  1. a series of transects across the Northeast U.S. Shelf for three decades, and
  2. a series of transects across the North Sea and its adjacent waters for four decades.

These collections represent the longest broad-scale spatial and temporal record of plankton response to environmental signals that exists for the North Atlantic. The data from these collections will be analyzed together with climatological data sets (the Comprehensive Ocean-Atmosphere Data Set, and the Air Temperature Data Set for the Northern Hemisphere) to study the link between zooplankton decadal variability and climatic variations.

In consideration of the comments provided by the panel and mail reviewers, and of changes in the budget, we have slightly modified the original research plan: The study area in the eastern North Atlantic has been restricted to the area with temporally uninterrupted sampling for more than three decades. One variable "total copepod count" has been added because several studies (e.g. Garrod and Colebrook, 1978; CPR Survey Team, 1992; Aebischer et al., 1990) indicate that large scale trends affect this index.

We will examine the decadal changes in the abundance of dominant, pan-Atlantic holozooplankton species (Calanus finmarchicus, Pseudocalanus spp., Centropages typicus, Temora longicornis, Metridia lucens, Acartia spp. and Centropages hamatus), and total copepod abundance, in the northeastern U.S. shelf (Gulf of Maine and Georges Bank). Primary focus will be on Calanus finmarchicus, a target GLOBEC species, and on total copepods. We will analyze the relationship between these changes and climatic variations in the northwestern Atlantic. Finally zooplankton variability will be compared between selected areas in the western and eastern Atlantic to study the relationship with transatlantic climatic variations.

To achieve these objectives we have set the following goals:

    Northwestern Atlantic - Temporal characterization of dominant holozooplankton species

  1. Quantitative analysis of the seasonal variations in the selected zooplankton species.
  2. Spatial characterization of the temporal patterns of the selected species.
  3. Identification of interannual patterns in the selected species.

    4. Determination of the relationship of zooplankton temporal patterns to climate variables

  4. Northwestern Atlantic: analysis of the association between zooplankton interannual variations and climatic variables.

    5. Inter Atlantic comparison: Comparison of temporal patterns of zooplankton species in the western Atlantic with those in the eastern Atlantic and North Sea.

  5. Test the hypothesis that the zooplankton in the area of the Gulf of Maine is modulated by the US continental climate, while the zooplankton of the British Isles areas is related to the oceanic climate of the North Atlantic.
  6. Test the hypothesis that the different patterns in zooplankton interannual variations in the eastern and western Atlantic are caused by influence of the North Atlantic Oscillation (NAO) on these areas.

Time series and other statistical analyses will be used to approach the objectives

This research project contributes to GLOBEC program objectives because: a) it proposes to analyze 35 years of Continuous Plankton Recorder zooplankton data, including GLOBEC target species Calanus finmarchicus and Pseudocalanus spp.; b) it seeks to link the interannual variations in the abundance of these species to climatic variations; and c) it seeks to understand the causes of zooplankton variations on the transatlantic scale, by analyzing the British and US zooplankton data sets together with climate indices. The results of these analyses can provide baseline information for predictive models on zooplankton variability in relation to climate change.