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How can the order in which organisms colonize an intertidal reef change the community that develops there?

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Diagram showing ocean zonation by depth and region, with labeled layers: littoral, sublittoral, bathyal, abyssal, and hadal along the seafloor, and epipelagic, mesopelagic, bathypelagic, and abyssalpelagic in open water. The littoral zone is at the high-tide mark. Vertical scale marks photic and aphotic zones from surface to 10,000 meters. — Marine ecosystem Zonation of the ocean. Note that in the littoral zone the water is at the high-tide mark.

The order in which organisms colonize an intertidal reef significantly influences the resulting biological community through processes of colonization and ecological succession. When bare space becomes available on a reef, the initial community composition is often determined by the specific types of larvae present in the local waters at that time.1

This sequence of arrival dictates the community structure because early colonizers can actively inhibit or facilitate the settlement of subsequent species. For instance, if tube worms establish themselves first, they may dominate the space; conversely, if algal spores colonize the shore first, they can prevent the settlement of those worms.1

Furthermore, competition plays a critical role in these dynamics. Once established, certain species may competitively overgrow neighbors or utilize chemical defenses to deter the growth of new arrivals, thereby altering the developmental trajectory of the entire assemblage. Because the availability of larvae varies, these patterns of succession are often difficult to predict with high accuracy.1