What do differences between north shelf and south shelf mean?
Differences in hydrography between the northern and southern Bering shelf are subtle, but biologically important. In the north, the temperature of the bottom water rarely rises above -1.7 deg C. And, the relatively gradual increase in temperature between the bottom and surface waters allows phytoplankton to accumulate in deep water. This accumulation of algal biomass in subsurface water is observed as high chlorophyll fluorescence by instruments on the CTD, and is called a sub-surface chlorophyll maximum (SCM). It also indicates presence of a concentrated food source that lasts for most of the summer. The cold bottom-water means that any food that reaches the seafloor enters a virtual refrigerator, so that bottom-dwelling organisms also have a long-term food supply. In contrast, the benthic refrigerator is not as cold in the south and there is no pronounced SCM. This means food resources further south are transient. The geographic location of the transition zone between these two regim
