Giant clams in shallow reefs: UV-resistance mechanisms of Tridacninae in the Red Sea

Rossbach, Susann; Overmans, Sebastian; Kaidarova, Altynay; Kosel, Jürgen; Agustı́, Susana; Duarte, Carlos M.

doi:10.1007/s00338-020-01968-w

Cited by 13 publications

(13 citation statements)

References 59 publications

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“…The contribution of different macro-benthos to total abundance revealed that Tridacna squamosa was almost entirely a dominating species, accounting for 100% of all recorded macro-benthos in the present study. Rossbach et al [24] stated that all three gigantic clam species were recorded for the Red Sea, T. maxima, T. squamosa, and T.…”

Section: Discussionmentioning

confidence: 99%

Effect of Environmental Variations on Macro-benthos Occurrence and Abundance of the Red Sea Coast of Egypt

El-Sokkary

Obuid-Allah²,

El-Wakeil³

et al. 2022

Assiut University Journal of Multidisciplinary Scientific Resea

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Section: Discussionmentioning

confidence: 99%

Effect of Environmental Variations on Macro-benthos Occurrence and Abundance of the Red Sea Coast of Egypt

El-Sokkary

Obuid-Allah²,

El-Wakeil³

et al. 2022

Assiut University Journal of Multidisciplinary Scientific Resea

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“…At night, they retract their mantle and partially close their shells, presumably to deter predators, and because there is no light for photosynthesis. During periods of elevated temperatures or very high light levels, giant clams have the option to partially close their shells and retract their mantle, providing shading protection for themselves and their symbionts ( Rossbach et al ., 2020 ).…”

Section: Responses To Environmental Changementioning

confidence: 99%

Conserving threatened species during rapid environmental change: using biological responses to inform management strategies of giant clams

Watson

Neo

2021

Conservation Physiology

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Giant clams are threatened by overexploitation for human consumption, their valuable shells and the aquarium trade. Consequently, these iconic coral reef megafauna are extinct in some former areas of their range and are included in the International Union for Conservation of Nature (IUCN) Red List of Threatened Species and Convention on International Trade in Endangered Species of Wild Fauna and Flora. Now, giant clams are also threatened by rapid environmental change from both a suite of local and regional scale stressors and global change, including climate change, global warming, marine heatwaves and ocean acidification. The interplay between local- to regional-scale and global-scale drivers is likely to cause an array of lethal and sub-lethal effects on giant clams, potentially limiting their depth distribution on coral reefs and decreasing suitable habitat area within natural ranges of species. Global change stressors, pervasive both in unprotected and protected areas, threaten to diminish conservation efforts to date. International efforts urgently need to reduce carbon dioxide emissions to avoid lethal and sub-lethal effects of global change on giant clams. Meanwhile, knowledge of giant clam physiological and ecological responses to local–regional and global stressors could play a critical role in conservation strategies of these threatened species through rapid environmental change. Further work on how biological responses translate into habitat requirements as global change progresses, selective breeding for resilience, the capacity for rapid adaptive responses of the giant clam holobiont and valuing tourism potential, including recognizing giant clams as a flagship species for coral reefs, may help improve the prospects of these charismatic megafauna over the coming decades.

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“…Their dual reliance on autotrophy and heterotrophy and indeterminate growth makes them long-living indicators of coral reef health. Researchers have long understood their potential as reef biomonitors, through the geochemical signals encoded in their shells [ 1 ], their absorption of microplastics and other contaminants [ 2 ], and in recent years, through valvometric analysis of their behavior [ 3 , 4 ]. Valvometry is the study of bivalve shell opening and closing through proximity sensors such as electrodes [ 5 ], Hall effect magnetic sensors [ 6 ], machine-learning analysis of video [ 7 ], and accelerometers [ 8 ].…”

Section: Introductionmentioning

confidence: 99%

“…In giant clams, shell opening and closing have been found to be controlled by diurnal light availability [ 3 ], with the clams basking wide open to optimize photosynthetic production in the daylight hours, and closing partially at night. The clams close when exposed to predation [ 16 ], temperatures approaching their maximum thermal tolerance [ 3 ], and to minimize exposure to ultraviolet radiation, such as among intertidal populations [ 4 ]. Researchers in ethology have increasingly used giant clam shell closure as a model system to understand how mollusks balance food acquisition and predator avoidance [ 16 ].…”

Section: Introductionmentioning

confidence: 99%

Giant clams as open-source, scalable reef environmental biomonitors

et al. 2023

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Valvometry, the electronic measurement of bivalve shell opening and closing, has been demonstrated to be a valuable biomonitoring technique in previous ecological and environmental studies. Valvometric data has been shown to relate significantly to pollution, predation, animal stress and feeding activity. However, there is a need for valvometric techniques applicable to coral reef environments, which may provide critical insights into reef resilience to ocean warming and acidification. Giant clams are endemic to coral reefs and hold great promise as valvometric recorders of light availability, productivity and other environmental variables. Despite this promise, prior valvometric work on giant clams has been limited by specialized hardware less accessible to developing countries where many coral reefs are found. Here we report on an open-source approach that uses off-the-shelf components to monitor smooth giant clam (Tridacna derasa) valve opening behavior, and tests this approach in the simulated reef environment of the Biosphere 2 Ocean. Valvometric data corroborates the influence of light availability on diurnal behavior of giant clams. The clams basked during daylight hours to expose their photosymbionts to light, and adopted a partially-closed defensive posture at night. The animals showed variations in the frequency of complete closures, with most occurring during night-time hours when the animals prioritize filter-feeding activity, clapping their valves to expel pseudofeces from their gills. Closure frequency showed a significant relation to pH and a significant lagged relationship to chlorophyll-a productivity, which are both a function of algal productivity in the Biosphere 2 Ocean tank. These results suggest that the animals fed on phytoplankton following periodic bloom events in the Biosphere 2 Ocean during the experiment. We propose that giant clams exhibit behavioral plasticity between individuals and populations, and advocate for the more widespread use of valvometry to enable comparative studies of reef environment and animal health.

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Giant clams in shallow reefs: UV-resistance mechanisms of Tridacninae in the Red Sea

Cited by 13 publications

References 59 publications

Effect of Environmental Variations on Macro-benthos Occurrence and Abundance of the Red Sea Coast of Egypt

Effect of Environmental Variations on Macro-benthos Occurrence and Abundance of the Red Sea Coast of Egypt

Conserving threatened species during rapid environmental change: using biological responses to inform management strategies of giant clams

Giant clams as open-source, scalable reef environmental biomonitors

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