Transport

Bottom-up control on LCZ: Transport

In the eastern Bering Sea, zooplankton are not uniformly distributed across the middle and outer shelves.  Preliminary results at M2, show that currents differ between icy and non-icy years during the winter and spring.  Therefore, the zooplankton distribution and abundance we observe in any one year could result from differential advection in cold and warm years.  Also, it is unclear to what extent advection alters spatial overlap between trophic levels.  Advection to regions of limited primary production or increased predation could influence the carbon/energy flux through the system.  These questions can only be evaluated by synthesis of extant datasets.

Hypothesis 1.1  The summer distribution and abundance of LCZ species (Neocalanus spp. and T. inermis) over the Outer Domain results from spring immigration/cross-shelf transport of these species from the basin and continental slope regions, and differs between warm and cold years.

Hypothesis 1.2 LCZ species on the middle shelf (Calanus and T. raschii) have distributions and standing stocks that reflect along shelf flow (southward transport from wind driven ice, and northward transport from currents).

Hypothesis 1.3 The nutrient inventory at the end of winter (before the spring phytoplankton bloom) on the middle shelf is determined by on-shelf transport of nutrient-rich water and off-shelf transport of nutrient-poor water.

Question 1.1 How does cross-shelf flow differ between warm and cold years and how does it influence the distribution of nutrients and plankton?

Question 1.2 Are zooplankton transported south with the ice?

Question 1.3 Does flow through Unimak Pass introduce zooplankton to the southern middle shelf?

Question 1.4 Does the vertical distribution of zooplankton interact with mean currents?