Boulder and Gravel Seafloor

Boulder and gravel areas are the most spatially complex habitats. These areas range in structure from large piles of boulders to flat pavements of small cobbles and pebbles. Many of the more rugged features of the Long Island Sound were formed via deposition and scouring during the Wisconsin glaciation (ending approximately 10,000 years ago). The relative stability of rock substrates provide a home for many encrusting and mobile organisms, as seen below.

Sessile invertebrates such as the golden star tunicate (Botryllus schlosseri), finger sponge (Isodictya palmata) and frilled anemone (Metridium senile) colonize and expand upon rock reefs in the Long Island Sound.

The crevices between and under boulders, as well as seaweeds and epifauna, provide cover from predators and refuges from swift currents. A greater degree of spatial complexity allows for a wider range of sizes of organisms able to utilize such habitats. For example, adult cunner (Tautogolabrus adspersus; left) is a temperate reef fish which is often the dominant fish species among piled boulders. In less-elevated gravel areas, juvenile fishes and small crustaceans retreat from danger by burrowing directly beneath rocks and pebbles and hiding among the epifaunal species that colonize the hard rock surfaces.