Physiological Adaptations of Fishes to Tropical Intertidal Environments

Abstract

This chapter presents physiological adaptations of fishes to tropical intertidal environments. The chapter focuses on the tropical intertidal zone and describes the habitat types, the nature of environmental changes that fishes are likely to experience therein, and the major groups of resident fish. The intertidal zone is a unique environment between the land and the sea. It is characterized by changes in physical and chemical factors brought about by the day/night and tidal cycles. Mangroves, water-filled burrows on mudflats, tidepools on rocky shores, shallow seagrass beds and coral reef lagoons are typical habitats for intertidal fishes. Physical factors in the intertidal environment, such as temperature, salinity, pH, oxygen and carbon dioxide content of the water change according to day/night, the tidal cycle, and climatic change. Fishes that have evolved in this extreme habitat have special physiological, behavioral, and morphological adaptations to it. The intertidal zone is occupied by fishes with differing degrees of affinity to the habitat. Intertidal fish populations demonstrate a considerable degree of convergent evolution in searches to improve their fitness to the intertidal environment. The intertidal zone is also the place where fish, with considerable phenotypic plasticity, have evolved and spread to more stable environments such as sub‐tidal marine and freshwater systems.