characterization of underwater light regimes and target imaging in Lake Malawi

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Vision plays a critical role in mating where females choose amongst competing, displaying males of their species, while avoiding mating with sympatric heterospecifics. This process relies heavily on the co-evolution of visual sensitivity and the optical signal(s) used as critical display attributes, and on the visual environment where mate choice takes place. Here we will examine the influence of the photic environment on sexual selection, especially mate choice by female African cichlids, via intensive sampling of the natural ambient lighting conditions and simultaneous assessment of the mating behaviour of cichlids.Our fieldwork in Lake Malawi (July - September 2008) will measure species-specific habitat conditions (i.e. spectral irradiance, polarization characteristics and temporal and spatial variation of the underwater light environment. Simultaneous assessment of mating behaviour will be essential to guide the environmental measurements and ensure ecological relevance of such data. The team, including myself, Dr. Suzanne Gray (Postdoctoral Fellow) and Shai Sabbah (Ph.D. student) will employ several techniques for quantifying environmental parameters and behavioural observations. An integral part of this research will be the use of SCUBA by two members of the team, allowing them to make measurements directly where the fish are breeding. While at depth the divers will use a more sensitive spectroradiometer to make light measurements and high definition underwater video to assess visual behaviour.