Carbonate production of an emergent reef platform, Warraber Island, Torres Strait, Australia

Abstract

Complex relationships exist between tropical reef ecology, carbonate (CaCO 3 ) production and carbonate sinks. This paper investigates census-based techniques for determining the distribution and carbonate production of reef organisms on an emergent platform in central Torres Strait, Australia, and compares the contemporary budget with geological findings to infer shifts in reef productivity over the late Holocene. Results indicate that contemporary carbonate production varies by several orders of magnitude between and within the different reef-flat sub-environments depending on cover type and extent. Average estimated reef flat production was 1.66 ±1.78 kg m -2 yr -1 (mean ± SD) although only 23% of the area was covered by carbonate producers. Collectively, these organisms produce 17,399 ±18,618 t CaCO 3 yr -1 , with production dominated by coral (73%) and subordinate contributions by encrusting coralline algae (18%) articulated coralline algae, molluscs, foraminifera and Halimeda (<4%). Comparisons between these organisms production across the different reef flat zones, surface sediment composition and accumulation rates calculated from cores indicate that it is necessary to understand the spatial distribution, density and production of each major organism when considering the types and amounts of carbonate available for storage in the various reef carbonate sinks. These findings raise questions as to the reliability of using modal production rates in global models independent of ecosystem investigation, in particular, indicating that current models may overestimate reef productivity in emergent settings.

Calcified macroalgae - critical to coastal ecosystems and vulnerable to change: a review

“…They pointed to the importance of recognising and quantifying trophic resources as a dominant control determining the biogenic composition of carbonates. Hart and Kench (2007) investigated census-based techniques to determine the distribution and carbonate production of reef organisms on an emergent platform in Torres Strait (northern Australia). They found complex relationships between ecology, carbonate production and carbonate sinks.…”

“…Carbonate production was found to vary by several orders of magnitude across the different reef-flat subenvironments depending on their extent and cover type. Hart and Kench (2007) raise questions about the reliability of global models that use modal production rates without giving regard to the ecosystem context. They found significant differences between the proportion of total carbonate production contributed by the different reef-flat producers and their occurrence as constituents in surficial sediments of each ecological zone studied.…”

Calcification by Reef-Building Sclerobionts

“…storms [26]. However, relatively few studies have documented encruster calcification [9], [27], [28], with the majority focusing on coralline algae [29]–[31] or bulk (combined) encruster calcification [13]. As few studies have quantified fine-scale or organism specific rates of calcification for encrusters, prior estimates of reefal carbonate production (varying from local to global scales) have simply extrapolated from a limited number of reef studies, e.g.…”

Calcium Carbonate Production, Coral Cover and Diversity along a Distance Gradient from Stone Town: A Case Study from Zanzibar, Tanzania

“…Collectively, reef calcifiers produce 7,250 t CaCO 3 km −2 yr −1 , with corals dominating carbonate production (73%) (Hart and Kench, 2007). Calcium carbonate (CaCO 3 ) produced within coral reefs accounts for more than 25% of the total CaCO 3 buried in marine sediments globally (Jones et al, 2015).…”