Early colonization by marine ecosystem engineers: settlement and metamorphosis of the Pacific oyster (Magallana gigas) in a complex sensory landscape of chemical, tactile and sound cues
Schmidlin, S. (2025). Early colonization by marine ecosystem engineers: settlement and metamorphosis of the Pacific oyster (Magallana gigas) in a complex sensory landscape of chemical, tactile and sound cues. VLIZ PhD Theses, 9. PhD Thesis. Ghent University, Faculty of Sciences, Marine Biology/Flanders Marine Institute (VLIZ): Gent, Oostende. 222 pp.
Part of: VLIZ PhD Theses. Flanders Marine Institute (VLIZ): Ostend. , more
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Document type: Dissertation
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| Abstract |
For marine invertebrates with a larval stage, settlement and metamorphosis represent critical life-history transitions. This irreversible shift from a pelagic to a benthic habitat is triggered by environmental cues that larvae use to identify suitable habitats for their species. Reef-building bivalves, including mussels and oysters, are an important subgroup of marine invertebrates, and their ecological role extends beyond the sustainment of their own populations. The biogenic reefs formed by aggregated adult bivalves improve the local environment in a variety of ways, earning them the title of ecosystem engineers. Settlement and metamorphosis, though sometimes grouped under the umbrella term "settlement" in the literature, are two distinct processes. For marine bivalves during settlement, larvae descend the water column and attach to a substratum. This attachment is potentially reversible, but metamorphosis, which follows settlement, is a permanent process in which larvae undergo physiological changes and become fixed to the substratum, beginning their sessile adult life. As habitat generalists, bivalves rely on a variety of cues to indicate the suitability of a habitat, including light, sound, hydrodynamics, biofilms, trophic conditions, and signals from conspecifics. Additionally, larvae can detect cues from predators or other organisms to assess habitat suitability.While a substantial body of research on these cues exists, there are still significant knowledge gaps. Chemical cues are relatively well-studied, but physical cues, such as sound and microtopography, remain less understood. Furthermore, the lack of species-specific data often leads to generalized conclusions across multiple taxa, which may not be entirely accurate. As scientific research disproportionately focuses on a small number of model organisms. There is also a lack of information regarding how the intera of multiple environmental cues is interpreted by larvae, or how cue perception may be impacted by anthropogenic changes to marine environment. Understanding the mechanisms underlying these critical processes for reef-building bivalves advances our knowledge of fundamental larval ecology, particularly settlement and metamorphosis as adaptive reproductive strategies. Additionally, as bivalve reefs are rapidly declining and restoration efforts are a priority for conservation, a better understanding of bivalve recruitment can improve the design of reef restoration projects.In this thesis, I experimentally investigate the settlement and metamorphic cues that influence bivalve larvae, focusing on how larvae respond to interacting cues and how cues can be modulated in ways that can impact their effectiveness. This work covers both chemical and physical cues, focusing especially on those with potential applications to improve recruitment on artificial reefs. |
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