Towards understanding the relationship between wind conditions and plankton patchiness

Abstract

We used (1) water temperature (a proxy for water movement), (2) chlorophyll (a proxy for phytoplankton), and (3) zooplankton (bulk, small, and large size classes) to investigate the relationship between changing wind conditions and spatial patterns along linear transects (n 5 150) in two basins, South Arm and Annie Bay, of Lake Opeongo (Ontario, Canada). The basins have similar biological characteristics, but South Arm is larger and is oriented along the prevailing westerly wind direction. Large‐scale patterns (.1 km) were described with an accumulation index, and wavelet analysis was used to describe small‐scale patterns (≪1 km). Spatial descriptors were correlated with five descriptors of wind conditions: (1) wind force, (2) scalar wind speed, (3) vector wind speed, (4) wind persistence, and (5) wind direction. Persistent westerly winds in South Arm resulted in more downwind accumulation of warm water and total and large‐bodied zooplankton than in Annie Bay, while chlorophyll and small zooplankton did not show consistent downwind accumulation. The predominance of small‐scale variability, particularly in large zooplankton, increased in the South Arm as the persistence and strength of westerly winds blowing parallel to the sampling transects increased. Only temperature showed such a pattern in the smaller Annie Bay. These patterns were not related to winds blowing at the time of sampling but rather to those blowing up to 12 h before sampling. Our observations provide a basis for future consideration of how simple surface winds may actually shape the nature of trophic interactions in lake ecosystems.