Physiological study of larval fishes: challenges and opportunities

Physiological Studies of larval fishes have lagged far behind those of adults, yet offer tremendous opportunities for expanding our knowledge of the basic biology of both marine and freshwater Fishes. Physiological studies of larval fishes call also improve research and management in areas of applied science, such as aquaculture, fisheries, and environmental assessment. Additionally, larval fishes can be highly effective as general animal models for understanding evolution, development and disease processes in vertebrates. While the small size of larval fishes may initially seem to preclude detailed physiological measurements, physiologists have taken advantage of larval transparency and permeability to drugs and toxins to collect many forms of quantitative physiological data. In this essay we present a number of microtechniques currently employed in larval fish to study the cardiovascular, muscular, neurological, and ionoregulatory systems. Several interesting phenomena, including allometry, developmental plasticity and epigenetic effects, are then discussed from the perspective of the specific contributions that have been or can be made by studies of fish larvae. Ultimately, the integration of larval fish physiology with studies of morphology and behaviour, is both highly feasibly and likely to strengthen basic and applied research in fishes.