Pelagic Habitat

The water column also provides "habitat" structure for a number of species, ranging in size from the smallest of organisms to larger fish such as the ocean sunfish (Mola mola; right).   During the spring, phytoplankton bloom and flourish, especially in convergence zones where the rivers meet the estuary. In these regions, nutrient inputs are elevated due to spring runoff and increased sunlight, creating an ideal conditions for primary producers.

Zooplankton, such as copepods graze upon the phytoplankton and other suspended food particles while other species like the moon jelly (Aurellia aurellia) feed on small zooplankters. The bottom-up transfer of energy through the food web enhances foraging opportunities for small fishes and crustaceans. There are also interactions between gelatinouszooplankton and small fishes that share the midwaters. For example, some fishes are resistant to the stinging cells of medusa and can use the tentacles and bell for shelter, like juvenile butterfish (Peprilus triacanthus) in the tentacles of the lions mane jelly (Cyanea capillata; right). Although these habitats are ephemeral in nature, they increase the chance of survival for individuals. Of course, fish can also fall prey to stinging cells of some gelatinous zooplankton.

The pelagic environment also provides a temporary medium for the larvae of benthic invertebrates and demersal fishes. The early life stages of some fishes and invertebrates are spent drifting passively in the water column, waiting for an optimal benthic medium to settle in. This juvenile goosefish (Lophius americanus; left) is pelagic but will soon migrate to the seafloor where it will assume the role of an ambush predator of demersal organisms.