Distribution fields for aquatic ecosystem components: method of optimization of correlation zones

A method was initially suggested for the identification of zones where there are strong correlations between two distribution fields. The method was based on outlining areas where the gradients of the two fields are in the same or opposite directions. In the present study, correlation zones were optimized by varying the range of angles between gradients, simultaneously changing the correlation value and zone area. The major role was given to the correlation value; the zone area was maintained so that the optimized correlation zone was significant. The method was applied in an attempt to establish the interaction of spatial distribution of a grazer (Cladocera) and its food (nanophytoplankton) in Lake Kinneret (Israel), using data from multidisciplinary surveys carried out on 26 December 1991 and 13 May 1993.