The raised coral reef complex of the Kenyan coast: Tridacna gigas U-series dates and geological implications

Accordi, Giovanni; Brilli, Mauro; Carbone, Federico; Voltaggio, Mario

doi:10.1016/j.jafrearsci.2010.02.003

Cited by 16 publications

(18 citation statements)

References 75 publications

(129 reference statements)

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“…Giant clams (Bivalvia: Cardiidae: Tridacninae) are the largest living bivalves. They live in close association with coral reefs throughout the Indo-Pacific (Lucas 1988 ) where they are ecologically important as biomass for predators/scavengers and substrates for epibionts, in addition to physically contributing topographic relief (important as nurseries for fish) and calcium carbonate to the reef framework (Govan et al 1993 ; Cabaitan et al 2008 ; Accordi et al 2010 ). Giant clams have also benefitted humans for millennia, through provision of food and materials (Hviding 1993 ).…”

Section: Introductionmentioning

confidence: 99%

The behaviour of giant clams (Bivalvia: Cardiidae: Tridacninae)

Soo

Todd

2014

Mar Biol

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Giant clams, the largest living bivalves, live in close association with coral reefs throughout the Indo-Pacific. These iconic invertebrates perform numerous important ecological roles as well as serve as flagship species—drawing attention to the ongoing destruction of coral reefs and their associated biodiversity. To date, no review of giant clams has focussed on their behaviour, yet this component of their autecology is critical to their life history and hence conservation. Almost 100 articles published between 1865 and 2014 include behavioural observations, and these have been collated and synthesised into five sections: spawning, locomotion, feeding, anti-predation, and stress responses. Even though the exact cues for spawning in the wild have yet to be elucidated, giant clams appear to display diel and lunar periodicities in reproduction, and for some species, peak breeding seasons have been established. Perhaps surprisingly, giant clams have considerable mobility, ranging from swimming and gliding as larvae to crawling in juveniles and adults. Chemotaxis and geotaxis have been established, but giant clams are not phototactic. At least one species exhibits clumping behaviour, which may enhance physical stabilisation, facilitate reproduction, or provide protection from predators. Giant clams undergo several shifts in their mode of acquiring nutrition; starting with a lecithotrophic and planktotrophic diet as larvae, switching to pedal feeding after metamorphosis followed by the transition to a dual mode of filter feeding and phototrophy once symbiosis with zooxanthellae (Symbiodinium spp.) is established. Because of their shell weight and/or byssal attachment, adult giant clams are unable to escape rapidly from threats using locomotion. Instead, they exhibit a suite of visually mediated anti-predation behaviours that include sudden contraction of the mantle, valve adduction, and squirting of water. Knowledge on the behaviour of giant clams will benefit conservation and restocking efforts and help fine-tune mariculture techniques. Understanding the repertoire of giant clam behaviours will also facilitate the prediction of threshold levels for sustainable exploitation as well as recovery rates of depleted clam populations.

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Section: Introductionmentioning

confidence: 99%

The behaviour of giant clams (Bivalvia: Cardiidae: Tridacninae)

Soo

Todd

2014

Mar Biol

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“…On the Kenya coast, Accordi et al . () recorded a series of U‐Th dates based on the analysis of the dense aragonite shells of Tridacna , expected to provide reliable ages. Assuming a closed system, most ages grouped in MIS 5, with one in MIS 7.…”

Section: Discussionmentioning

confidence: 99%

“…However, although the diagrams provided by Accordi et al . (, fig. 4) recognize important discontinuities within the sequences described, there is no attempt to correlate these, treating each locality as a separate entity.…”

Section: Discussionmentioning

confidence: 99%

“…This might suggest a brief interval with little fall in sea level, implying that the Takamaka Limestone represented an early phase of MIS 5, or, alternatively, that it was associated with MIS 7. Deposits of MIS 7 have been reported on the Kenya coast (Accordi et al ., ) where two distinct marine transgressions have been identified in late Pleistocene deposits (Caswell, ; Braithwaite, ) and on Madagascar [Battistini (); with new dates in Stephenson et al . ()].…”

Section: Stratigraphymentioning

confidence: 99%

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Last Interglacial changes in sea level on Aldabra, western Indian Ocean

Braithwaite

2020

Sedimentology

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The Pleistocene limestones on the island of Aldabra in the western Indian Ocean preserve a detailed record of the Last Interglacial interval. Sedimentological analysis has revealed that this interval, formerly regarded as reflecting rapid sea‐level rise, during global warming, followed by a more gradual fall towards the low sea level of the Last Glacial Maximum, in fact shows much greater variation. Although data do not support an accurate chronology, there is evidence that reversals in sea‐level trend caused both pauses in deposition and concurrent erosion during sea‐level rise, and both stillstands and erosion during sea‐level fall. Data include sea‐level related variations in coral morphology, discontinuities and boundaries within depositional sequences, and changes in biofacies. These may explain inconsistencies in the radiometric ages of deposits within the unit, but question the nature of the interglacial cycle, the mechanisms driving it and, in particular, whether comparable variation occurred elsewhere.

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“…Significant sea-level fluctuations during MI5 Se have been reported in many sites from geomorphological and morphostrati graphic evidence (Plaziat et al, 1998;Dumas et al, 2006;Rohling et al, 2008;Accordi et al, 2010). A global MI5 Se sea-level curve has been presented by Hearty et al (2007), with assumed average duration between 130 ± 2 and 119 ± 2 ka.…”

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confidence: 99%