Intra-Group Activity Changes in Response to Altered Turbidity

Abstract

The cooperatively breeding cichlid Neolamprologus pulcher engages in competitive social displays to maintain a complex hierarchy including a breeding pair and many subordinate helper individuals. These displays are largely visual, thus susceptible to changes in water visibility through changes in turbidity. Using previously scored data on intra-group behavioral activity and displays, we sought out to analyze how turbidity affected overall intra-group activity levels in individuals by comparing activity levels against the relative turbidity levels of observation days and locations to determine how turbidity may affect activity levels. We found that different intensities of turbidity resulted in differing activity levels based on an individual’s position in the group hierarchy, with the intermediate condition yielding higher activity for fish that were not the dominant male. Dominant males, however, showed a decrease in activity between intermediate and high turbidity but no significant difference in activity between the intermediate and low turbidity. This has broader implications on the ecological effects of environmental conditions in visually mediated aquatic displays, particularly in relation to anthropogenically-caused turbidity.