Estimating rates of biologically driven coral reef framework production and erosion: a new census-based carbonate budget methodology and applications to the reefs of Bonaire

Census-based approaches can provide important measures of the ecological processes controlling reef carbonate production states. Here, we describe a rapid, non-destructive approach to carbonate budget assessments, termed ReefBudget that is census-based and which focuses on quantifying the relative contributions made by different biological carbonate producer/eroder groups to net reef framework carbonate production. The methodology is presently designed only for Caribbean sites, but has potential to be adapted for use in other regions. Rates are calculated using data on organism cover and abundance, combined with annual extension or production rate measures. Set against this are estimates of the rates at which bioeroding species of fish, urchins and internal substrate borers erode reef framework. Resultant data provide a measure of net rates of biologically driven carbonate production (kg CaCO3 m(-2) year(-1)). These data have potential to be integrated into ecological assessments of reef state, to aid monitoring of temporal (same-site) changes in rates of biological carbonate production and to provide insights into the key ecological drivers of reef growth or erosion as a function of environmental change. Individual aspects of the budget methodology can also be used alongside other census approaches if deemed appropriate for specific study aims. Furthermore, the methodology spreadsheets are user-changeable, allowing local or new process/rate data to be integrated into calculations. Application of the methodology is considered at sites around Bonaire. Highest net rates of carbonate production, +9.52 to +2.30 kg CaCO3 m(-2) year(-1), were calculated at leeward sites, whilst lower rates, +0.98 to -0.98 kg CaCO3 m(-2) year(-1), were calculated at windward sites. Data are within the ranges calculated in previous budget studies and provide confidence in the production estimates the methodology generates

Fine sediment trapping in two mangrove-fringed estuaries exposed to contrasting land-use intensity, Palau, Micronesia

A comparative study was undertaken of the fate of fine sediment in the Ngerikiil and Ngerdorch mangrovefringed\ud estuaries in Babeldaob Island, Palau, Micronesia, in 2002. The mangroves comprised 3.8% of each catchment area, and in both systems, they trapped about 30% of the riverine sediment. Mangroves are important buffers protecting fringing coral reefs from excessive sedimentation. The sediment yield was significantly higher in the Ngerikiil River catchment (150 tons km2 yr1) that has been extensively cleared and farmed, than in Ngerdorch River catchment (1.9 tons km2 yr1) that was still relatively pristine during the study period

Age accuracy and resolution of Quaternary corals used as proxies for sea level

The accuracy of global eustatic sea level curves measured from raised Quaternary reefs, using radiometric ages of corals at known heights, may be limited by time-averaging, which affects the variation in coral age at a given height. Time-averaging was assessed in uplifted Holocene reef sequences from the Huon Peninsula, Papua New Guinea, using radiocarbon dating of coral skeletons in both horizontal transects and vertical sequences. Calibrated 2 sigma age ranges varied from 800 to 1060 years along horizontal transects, but weighted mean ages calculated from 15-18 dates per horizon were accurate to a resolution within 154-214 yr. Approximately 40% of the variability in age estimate resulted from internal variability inherent to C-14 estimates, and 60% was due to time-averaging. The accuracy of age estimates of sea level change in studies using single dated corals as proxies for sea level is probably within 1000 yr of actual age, but can be resolved t

Ecological persistence interrupted in Caribbean coral reefs [Letter]

The recent mass mortality of Caribbean reef corals dramatically altered reef community structure and begs the question of the past stability and persistence of coral assemblages before human disturbance began. We report within habitat stability in coral community composition in the Pleistocene fossil record of Barbados for at least 95 000 years despite marked variability in global sea level and climate. Results were consistent for surveys of both common and rare taxa. Comparison of Pleistocene and modern community structure shows that Recent human impacts have changed coral community structure in ways not observed in the preceding 220 000 years

Heliolitid corals and their competitors: a case study from the Wellin patch reefs, Middle Devonian, Belgium

peer reviewedWellin patch reefs are small Upper Eifelian build?ups within the fine?grained argillaceous limestone of the Hanonet Formation. Whereas the reefs themselves are not well exposed, their fossil assemblage is accessible in the hills near the town of Wellin, approximately 40xA0km SE of Dinant in Belgium. It is especially rich in massive stromatoporoids, heliolitids and other tabulate corals. They exhibit predominantly domical and bulbous morphologies. This paper focuses primarily on the palaeoautoecology of the heliolitid corals and their relationships with other organisms. Cases of mutual overgrowth between heliolitids, other corals and stromatoporids suggest a high degree of competition for space on the reefs, possibly related to the scarcity of hard substrates. Coral and stromatoporoid growth forms, as well as the prevalence of micritic matrix, point to a relatively low energy environment. However, abundant growth interruption surfaces, sediment intercalations and rejuvenations of corals suggest episodically increased hydrodynamic regime and sediment supply. It is inferred that the patch reefs developed in a relatively shallow environment, where the reefal assemblage was regularly affected by storms. Heliolitids exhibited high sediment tolerance and relied on passive sediment removal for survival. They also could regenerate effectively and commonly overgrew their epibionts, after the colony’s growth was hampered by the sediment. This is recorded in extremely abundant growth interruption surfaces, which allow the analysis of the impact of sediment influxes on the heliolitid corals. ? 2021 Lethaia Foundation. Published by John Wiley & Sons Lt