Module 2. Zooplankton production and advection

Participants:
Webjørn Melle (IMR)(Module leader), Geir Huse (IMR), Geir Ottersen (IMR/BI, UoO)

Objective:
Explore the effects of ocean climate and circulation on the production and advection of Calanus finmarchicus onto the northern Norwegian Shelf and the Barents Sea.

We will explore the effect of climate on the advection of C. finmarchicus to the Northern Norway shelf areas and the Barents Sea by statistical analysis of physical and biological time series data and model simulations.

Existing time series, available at the University of Bergen and Institute of Marine Research, of meteorological, hydrographic, phytoplankton and zooplankton data spanning the time period from the mid 1970-ies to present will be used. The data represent seasonal area mapping of the Barents and Norwegian Seas and repeated coverage of fixed transects, and fixed stations (including Weather Station Mike). Russian data from the Norwegian and Barents Seas will be part of the study if a bilateral cooperation between PINRO and IMR can be established. Overview of the data is shown in the table.

Statistical analysis of the time series will be applied to explore the relationships between zooplankton concentration in the Norwegian Sea and the adjacent continental shelves of the coast of northern Norway and the Barents Sea. Further, the data will be compared to large-scale weather pattern such as the NAO.

The statistical analysis will be complemented by a mechanistic, individual-based model (IBM) of Calanus, that includes growth, mortality, reproduction, and vertical migration. Vertical migration strategies documented in previous studies will be implemented. The IBM will be used to investigate the interaction between seasonal variation in advective forcing and vertical migration of Calanus. The physical model described in Module 1 will generate current velocities, phytoplankton abundance, and temperature fields to be used in the IBM. In addition to the component advected from the Norwegian Sea, there is local production of Calanus in the Barents Sea. The model will be used to investigate how different climatic conditions impact on the relative abundance of advected and local Calanus. These issues will be addressed through hindcast analysis of years with different climatic conditions from the period 1970-2000.

Available data from UoB and IMR. Potentially available data from PINRO (Russia). Russian data we wish to make available for the project through agreements on collaboration between PINRO and IMR. After 1980, chlorophyll and nutrients time series are available from where and when zooplankton time series, conducted by IMR, are available.

Workplan:

• Retrieve time series of meteorological, hydrographic, phytoplankton and zooplankton data.
  
• Statistical data analysis will be applied to study ecological patterns and examine their links to climate variability. Both exploratory studies and confirmatory studies will be applied. The analyses will focus on time series methods. We will initially apply traditional linear autoregressive (ARIMA) models (Box and Jenkins, 1976). Later on possibly nonlinear relations will be examined by methods like treshhold autoregressive (TAR) and generalized additive (GAM) modelling (Hastie and Tibshirani, 1990).
  
• Simulate the advection of Calanus in selected years in a hindcast analysis to elucidate how climatic variability and seasonal vertical migration impacts on the rate of advection into the Barents Sea. Furthermore the local production of Calanus will be compared with the advected component under different environmental states.
  
• Disseminate time series data and results of statistical analyses and model simulations to Module 3.