Monitoring marine plankton ecosystems. I: Description of an ecosystem approach based on plankton indicators

A procedure is presented that allows monitoring of the dynamic regime of pelagic ecosystems in the North Atlantic Ocean. It uses a diversity index (mean number of species per con- tinuous plankton recorder (CPR) sample) and species assemblage indicators calculated from all calanoid copepods (108 species) identified by the CPR survey since 1958. In any region of the North Atlantic covered by the CPR survey, the procedure calculates the values of these ecosystem indica- tors using a constant number of samples, selected randomly, and checks any bias associated with the spatial and temporal heterogeneity of the sampling. The procedure is described and illustrated in this study using CPR data in the central North Sea. The usefulness of this tool is demonstrated by a study of the sensitivity of the indicators to the number of CPR samples employed in the estimation of monthly or annual means. Firstly, it is shown that on an annual scale the procedure improves the quality of estimations. However, when long-term changes of a plankton indicator are examined for a particular month, it is crucial to use an appropriate number of CPR samples to detect a significant link between the biological and hydro-climatic environment. Secondly, the importance of using species assemblage indicators is demonstrated. They allowed the detection and the ecological interpretation of both episodic events and the regime shift in the central North Sea. It is shown that the regime shift in the North Sea had a strong impact on plankton community structure and was marked by an increase in diversity related to a progressive increase in warm-water species and a decrease in cold-water species. This study also has important implications for researchers using the CPR data. It demonstrates the robustness of the CPR data, but on the other hand also shows that the spatial and temporal heterogeneity should be assessed with care before interpreting the long-term changes of a CPR-derived plankton indicator.

[1]  Gwilym M. Jenkins,et al.  Time series analysis, forecasting and control , 1972 .

[2]  E. Svendsen,et al.  A regime shift in the North Sea circa 1988 linked to changes in the North Sea horse mackerel fishery , 2001 .

[3]  G. Beaugrand,et al.  Spatial dependence of calanoid copepod diversity in the North Atlantic Ocean , 2002 .

[4]  R. Steneck.  Human influences on coastal ecosystems: does overfishing create trophic cascades? , 1998, Trends in ecology & evolution.

[5]  Michel J. Kaiser,et al.  The effects of fishing on marine ecosystems , 1998 .

[6]  S. Carpenter,et al.  Catastrophic shifts in ecosystems , 2001, Nature.

[7]  M. Heath,et al.  Climate fluctuations and the spring invasion of the North Sea by Calanus finmarchicus , 1999 .

[8]  P. C. Reid,et al.  Ocean climate anomalies and the ecology of the North Sea , 2002 .

[9]  M. Edwards,et al.  Differences in performance among four indices used to evaluate diversity in planktonic ecosystems , 2001 .

[10]  M. Edwards,et al.  Exceptional influx of oceanic species into the North Sea late 1997 , 1999, Journal of the Marine Biological Association of the United Kingdom.

[11]  W. Greve.  The 1989 German Bight invasion of Muggiaea atlantica , 1994 .

[12]  Hughes,et al.  Biological consequences of global warming: is the signal already apparent? , 2000, Trends in ecology & evolution.

[13]  B. Planque,et al.  Biodiversity of North Atlantic and North Sea calanoid copepods , 2000 .

[14]  P. C. Reid,et al.  Spatial, seasonal and long-term fluctuations of plankton in relation to hydroclimatic features in the English Channel, Celtic Sea and Bay of Biscay , 2000 .

[15]  G. Hays.  Mesh selection and filtration efficiency of the Continuous Plankton Recorder , 1994 .

[16]  Elliott A. Norse.  Global marine biological diversity: a strategy for building conservation into decision making , 1994 .

[17]  P. C. Reid,et al.  Variations in the abundance of Centropages typicus and Calanus helgolandicus in the North Sea: deviations from close relationships with temperature , 2002 .

[18]  P. C. Reid,et al.  Reorganization of North Atlantic Marine Copepod Biodiversity and Climate , 2002, Science.

[19]  J. Colebrook.  Continuous plankton records: relationships between species of phytoplankton and zooplankton in the seasonal cycle , 1984 .

[20]  J. Fromentin,et al.  Calanus and environment in the Eastern North Atlantic. I. Spatial and temporal patterns of C. finmarchicus and C. helgolandicus , 1996 .

[21]  Arnold Taylor,et al.  North–South shifts of the Gulf Stream and their climatic connection with the abundance of zooplankton in the UK and its surrounding seas , 1995 .

[22]  H. Lindeboom.  Protected areas in the North Sea: An absolute need for future marine research , 1995, Helgoländer Meeresuntersuchungen.

[23]  P. C. Reid,et al.  Diversity of calanoid copepods in the North Atlantic and adjacent seas: species associations and biogeography , 2002 .

[24]  S. Levitus,et al.  “Great Salinity Anomalies” in the North Atlantic , 1998 .

[25]  G. Hays,et al.  Sampling by the Con-tinuous Plankton Recorder survey , 1994 .

[26]  B. Planque,et al.  Long-term and regional variability of phytoplankton biomass in the Northeast Atlantic (1960-1995) , 2001 .

[27]  J. Geller,et al.  Ecological Roulette: The Global Transport of Nonindigenous Marine Organisms , 1993, Science.

[28]  F. S. Russell,et al.  Hydrographical and Biological Conditions in the North Sea as Indicated by Plankton Organisms , 1939 .

[29]  J. Castilla,et al.  The management of fisheries and marine ecosystems , 1997 .

[30]  P. Legendre,et al.  SPECIES ASSEMBLAGES AND INDICATOR SPECIES:THE NEED FOR A FLEXIBLE ASYMMETRICAL APPROACH , 1997 .

[31]  J. Lindley,et al.  Geographical distribution and seasonal and diel changes in the diversity of calanoid copepods in the North Atlantic and North Sea , 2001 .

[32]  P. C. Reid,et al.  2 Interregional biological responses in the North Atlantic to hydrometeorological forcing , 2002 .

[33]  B. Planque,et al.  Calanus and environment in the eastern North Atlantic. 2. Role of the North Atlantic Oscillation on Calanus finmarchicus and C. helgolandicus , 1996 .

[34]  A. H. Taylor,et al.  The relationship between Gulf Stream position and copepod abundance derived from the Continuous Plankton Recorder Survey: separating biological signal from sampling noise , 1993 .

[35]  R. Peterman,et al.  Comparison of methods to account for autocorrelation in correlation analyses of fish data , 1998 .

[36]  Ah Taylor,et al.  Latitudinal displacements of the gulf-stream (1966 to 1977) and their relation to changes in temperature and zooplankton abundance in the ne atlantic , 1980 .

[37]  S. Spoel.  The basis for boundaries in pelagic biogeography , 1994 .

[38]  C. S. Holling.  Resilience and Stability of Ecological Systems , 1973 .

[39]  E. Henderson,et al.  High salinity in the North Sea , 1991, Nature.

[40]  J. Lindley,et al.  Anomalous seasonal cycles of decapod crustacean larvae in the North Sea plankton in an abnormally warm year , 1993 .

[41]  Chris Chatfield,et al.  The Analysis of Time Series: An Introduction , 1981 .

[42]  M. Omori,et al.  Impact of human activities on pelagic biogeography , 1994 .

[43]  G. Becker.  Sea surface temperature changes in the North Sea and their causes , 1996 .

[44]  A. J. Warner,et al.  Doliolids in the German bight in 1989: Evidence for exceptional inflow into the North Sea , 1990, Journal of the Marine Biological Association of the United Kingdom.