The Consequences of Complex Larval Behavior in a Coral

Abstract

The leaf coral Agaricia humilis occurs mainly on the undersides of surfaces in shallow water, a distribution different from the vast majority of corals at our study site in Bonaire, Netherlands Antilles. A series of hypotheses were tested for specific mechanisms that could cause the observed distributions of Agaricia humilis. We found that a suite of larval swimming and settling behaviors, in large part, drives the adult distribution of the species. These behaviors include: (1) swimming behavior that causes larvae to position themselves in shallow water, (2) orientation behavior during settlement that causes larvae to preferentially settle on the undersides of surfaces, and (3) settlement behavior where chemosensory recognition of morphogenic molecules associated with the cell walls of specific crustose red algae is required for induction of settlement and metamorphosis. The consequences of atypical larval behavior are severe and include decreased survivorship, growth, and ability to reproduce sexually.

Pelagic conditions affect larval behavior, survival, and settlement patterns in the Caribbean coral Montastraea faveolata

“…However, recent studies have shown that coral planulae move both actively and passively during dispersal and exhibit complex larval behavior during settlement (Babcock & Mundy 1996, Raimondi & Morse 2000, Stake & Sammarco 2003. When considering larval behavior, one should be aware that life-history elements (i.e.…”

Benthic habitat map of U.S. Coral Reef Task Force Faga‘alu Bay priority study area, Tutuila, American Samoa

“…Crustose coralline algae (CCA) can be beneficial as it encrusts and binds reef rubble, thus providing a stable substrate for coral recruitment after a major disturbance. CCA has also been shown to induce metamorphosis and settlement of coral larvae as well as increase survivorship of recruits (Morse and others, 1988;Morse and Morse, 1991;Heyward and Negri, 1999;Raimondi and Morse, 2000;Harrington and others, 2004). Many of the small corals (<100 cm in diameter) found on reef rubble on the reef flat have likely attached or settled since the 2009 tsunami, and their subsequent growth may be indicative of the coral reef ecosystem's slow recovery.…”

Proceedings of the Smithsonian Marine Science Symposium

“…One fi eld study showed that multiple behavioral choices determined the larval settlement site of the Caribbean brooder Agaricia humilis (Raimondi and Morse, 2000). The larvae swam down when restricted to 3 and 8 m but swam toward the surface when restricted to 25 m. In further fi eld experiments, larvae settled in response to the coralline alga Hydrolithon boergesenii but would only settle directly on the coralline alga when it was on the underside of a settlement tile.…”