MEPS

Marine Ecology Progress Series

MEPS is a leading hybrid research journal on all aspects of marine, coastal and estuarine ecology. Priority is given to outstanding research that advances our ecological understanding.

Online: ISSN 1616-1599

Print: ISSN 0171-8630

DOI: https://doi.org/10.3354/meps

Impact Factor2.1 (JCR 2025 release)

Article Acceptance Rate52.2% (2024)

Average Time in Review216 days (2024)

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Volume contents
Mar Ecol Prog Ser 335:1-18 (2007)

Individual-based model of larval transport to coral reefs in turbulent, wave-driven flow: behavioral responses to dissolved settlement inducer

ABSTRACT: Larvae of many benthic marine animals settle and metamorphose in response to waterborne chemical cues. Can the behavioral responses of microscopic larvae in the water column to dissolved chemical cues affect their transport to the substratum in the turbulent, wave-driven flow characteristic of many shallow coastal habitats? We addressed this question using an individual-based model of larvae of the sea slug Phestilla sibogae, transported in the oscillatory flow above coral reefs. Larvae of P. sibogae stop swimming and sink in response to a dissolved inducer released by their prey, the coral Porites compressa, and resume swimming when exposed to inducer-free water. The instantaneous fine-scale spatial distribution of inducer in the flow above a reef is filamentous; hence microscopic larvae swimming or sinking through the water encounter inducer above threshold concentration in on/off temporal patterns. Model results show that using a time-averaged inducer concentration gradient to calculate larval transport rates to the reef overestimates the rates by <15% (depending on the threshold concentration of inducer required to trigger larval sinking) compared with those calculated using time-varying, fine-scale inducer distributions. Aspects of larval behavior that have large effects on rates of transport to the substratum are swimming speed and direction, sinking speed, and sensitivity (threshold concentration) and responsivity (percent of encounters eliciting a response) to inducer. In contrast, lag times to start sinking after encountering inducer or to resume swimming after re-entering inducer-free water, have negligible effect.

KEYWORDS

Laser-illuminated slice through a dye cloud (analogue for odor) released from corals into wave-driven water flow above a reef; inset: larva of Phestilla sibogae. Photos: Matthew Reidenbach & Jeffrey Koseff (laser image), Michael Hadfield (inset)

Like many bottom-dwelling marine animals, the coral-eating sea slug Phestilla sibogae produces microscopic larvae that are carried away by ocean currents. Where marine larvae settle and survive on the sea bottom affects the biodiversity of marine communities. How do tiny larvae, swirling around in turbulent, wave-driven flow, land in suitable habitats? Phestilla larvae sink when they encounter the aroma of their prey coral, Porites, and resume swimming in odor-free water. Laser experiments revealed that, on the scale of a larva, the cloud of odor above a coral reef is composed of fine aroma filaments. The simple off/on response to brief encounters with odor filaments enhances the probability of the larvae being carried by turbulent flow into a reef inhabited by their prey coral.

M. A. R. Koehl (Co-author)

  • Department of Integrative Biology, University of California, 3060 Valley Life Sciences Building, Berkeley, California 94720-3140, USA

J. A. Strother (Co-author)

  • Department of Integrative Biology, University of California, 3060 Valley Life Sciences Building, Berkeley, California 94720-3140, USA

M. A. Reidenbach (Co-author)

  • Environmental Fluid Mechanics Laboratory, Department of Civil and Environmental Engineering, Stanford University, Palo Alto, California 94305-4020, USA

J. R. Koseff (Co-author)

  • Environmental Fluid Mechanics Laboratory, Department of Civil and Environmental Engineering, Stanford University, Palo Alto, California 94305-4020, USA

M. G. Hadfield (Co-author)

  • Kewalo Marine Laboratory, University of Hawaii, 41 Ahui Street, Honolulu, Hawaii 96813, USA