Photobiology of the zoanthid Zoanthus sociatus in intertidal and subtidal habitats

Abstract

Intertidal environments are boundaries between marine and terrestrial ecosystems that are subject to rapid fluctuations across tidal cycles. This study investigates, for the first time, the photobiology of symbiotic zoanthids inhabiting different tidal environments: subtidal, intertidal pools and intertidal areas exposed to air during low tide. More specifically, we assessed the photochemical efficiency, Symbiodinium density and photosynthetic pigments profile of Zoanthus sociatus during low tide. Photochemical efficiency was lower and cell density higher in air exposed zoanthids. The profile of photosynthetic pigments also varied significantly among tidal habitats, particularly photoprotective pigments such as dinoxanthin and diadinoxanthin. Differences were also observed for the pigment content per cell, but the proportion of particular pigments (peridinin/chlorophyll-a and diatoxanthinþdiadinoxanthin/chlorophyll-a) remained stable. Results suggest that aerial exposure conditions induce reversible downregulation of photochemical processes but no photophysiological impairment or bleaching. These findings provide a baseline for future studies addressing the prevalence of these overlooked cnidarians in environmentally dynamic reef flats.

Effects of low pH and high temperature on two Palythoa spp. and predator–prey interactions in the subtropical eastern Atlantic

“…However, it has been demonstrated that size and weight greatly fluctuate in soft‐bodied organisms owing to their physiological state or in response to environmental disturbances (Fabricius, 1995; Hellström & Benzie, 2011). Moreover, previous studies have highlighted that photochemical efficiency in polyps that were cyclically emerged were lower than in polyps that were always immersed (Leal et al, 2015; Rosa et al, 2016). Nevertheless, under environmental stress the host can change its main feeding behaviour from autotrophy to heterotrophy (Gustafsson, Baird & Ralph, 2013).…”

Zoantharian Endosymbiont Community Dynamics During a Stress Event

“…However, the host can associate with at least three Symbiodiniaceae lineages that likely represent distinct species (Wham et al, 2014;Wham, 2015). Two of the lineages are primarily found in the shallows (Symbiodinium A1z in direct sunlight and Cladocopium C1z-intertidal in shadow; Reimer, 2008), while the other is primarily found at greater depth (Cladocopium C1z-subtidal), suggesting that they are adapted to different light levels and possibly different temperatures (Kamezaki et al, 2013;Leal et al, 2016).…”