Water Body Type Influences Climate–Growth Relationships of Freshwater Drum

Abstract

AbstractClimate–growth relationships of fish are of increasing research interest. However, few studies have attempted to characterize the extent to which climate–growth relationships may diverge across fundamentally different types of environments. The goal of this study was to examine the effects of climate variability (i.e., temperature, precipitation, global climate indices) on the growth of Freshwater Drum Aplodinotus grunniens and determine the extent to which these relationships differ between lotic and lentic habitats. Freshwater Drum were collected from five river and five reservoir environments in Georgia, Alabama, and Mississippi. Tree‐ring techniques were used to standardize annual growth for age (measured using interannual growth increments from otolith sagittae) and growth indices were correlated to annual thermal, hydrologic, and global climate indices. Freshwater Drum expressed distinct and significant climate–growth relationships by water body type. The general pattern observed was that annual drum growth in rivers was significantly correlated to days of year of maximum flow while annual drum growth in reservoirs was significantly correlated to annual variation in number of growing degree‐days (GDD). Furthermore, the strength of growth–GDD correlations for drum increased predictably alongside hydraulic retention time of reservoirs. This study reveals that water body type can govern climate–growth relationships in fish and suggests biologists need to be wary of assuming that patterns documented in one population would be wholly applicable to another.