Spatio-Temporal Patterns in Coral Reef Communities of the Spermonde Archipelago, 2012–2014, I: Comprehensive Reef Monitoring of Water and Benthic Indicators Reflect Changes in Reef Health

Abstract

Pollution, fishing, and outbreaks of predators can heavily impact coastal coral reef ecosystems, leading to decreased water quality and benthic community shifts. To determine the main environmental drivers of coral reef status in the Spermonde Archipelago, Indonesia, we monitored environmental variables and coral reef benthic community structure along an on-to-offshore gradient annually from 2012 to 2014. Findings revealed that concentrations of phosphate, chlorophyll a-like fluorescence, suspended particulate matter, and light attenuation significantly decreased from on-to-offshore, while concentrations of dissolved O 2 and values of water pH significantly increased on-to-offshore. Nitrogen stable isotope signatures of sediment and an exemplary common brown alga were significantly enriched nearshore, identifying wastewater input from the city of Makassar as primary N source. In contrast to the high temporal variability in water quality, coral reef benthic community cover did not show strong temporal, but rather, spatial patterns. Turf algae was the dominant group next to live coral, and was negatively correlated to live coral, crustose coralline algae (CCA), rubble and hard substrate. Variation in benthic cover along the gradient was explained by water quality variables linked to trophic status and physico-chemical variables. As an integrated measure of reef status and structural complexity, the benthic index, based on the ratio of relative cover of live coral and CCA to other coral reef organisms, and reef rugosity were determined. The benthic index was consistently low nearshore and increased offshore, with high variability in the midshelf sites across years. Reef rugosity was also lowest nearshore and increased further offshore. Both indices dropped in 2013, increasing again in 2014, indicating a period of acute disturbance and recovery within the study and suggesting that the mid-shelf reefs are more resilient to disturbance than nearshore reefs. We thus recommend using these two indices with a selected number of environmental variables as an integral part of future reef monitoring.

Breaking Resilience for a Sustainable Future: Thoughts for the Anthropocene

“…On the small reef atolls, high population densities combine increasingly western consumer habits with growing lack of space and fresh water. Under water, chronic exposure to anthropogenic effluents and overfishing have created "non-coral" reefs that display a resilient combination of turf algae-dominated habitats and functionally deficient fish communities (Plass-Johnson et al, 2016Teichberg et al, 2018). This undesirable system state is subject to strongly rooted stabilizing feedback loops the coral predator and after Acanthaster planci (crown-of-thorns outbreak in 2013; Plass-Johnson et al, 2015 and is, at the same time, unresponsive to destabilizing forces (coral recruitment; Sawall et al, 2013) that might put the reefs on a more desirable trajectory.…”

Contrasting Responses in the Niches of Two Coral Reef Herbivores Along a Gradient of Habitat Disturbance in the Spermonde Archipelago, Indonesia

“…Benthic communities were quantified in parallel with Teichberg et al (2018) and Plass-Johnson et al (2018). At each island there were 50 photographic quadrats per 50 m transect.…”

“…It should be noted that samples of Padina sp. were also used as indicators of environmental condition within Teichberg et al (2018). Collection depth was always 5 m below low tide to standardize light-associated change in plant isotopic values.…”

“…The effects of terrestrially-derived disturbance gradients in marine waters across coral reefs have been noted from many parts of the world (Edinger et al, 1998;Mallela et al, 2004;Fabricius et al, 2005;Lirman and Fong, 2007;Teichberg et al, 2018). Coral reefs closer to shore are generally characterized by less hard coral abundance, an increase in fleshy algae, a general loss of habitat complexity, and by a decrease in coral and fish species diversity or even complete shifts in the sets of species (Fabricius et al, 2005;Plass-Johnson et al, 2015a.…”

Spatio-Temporal Patterns in the Coral Reef Communities of the Spermonde Archipelago, 2012–2014, II: Fish Assemblages Display Structured Variation Related to Benthic Condition

“…This site, however, should not be interpreted as a control because the presence of some fish species is determined by unique ecological niches created by the site's specific oceanographic conditions. At each site, three 50 m permanent transects were installed along the reef and parallel to the shore, where all fish, benthic, and water environmental data were collected (see Teichberg et al, 2018 for details on water environmental data). Transects were standardized at 2 m below the reef crest, which for each site fell between 4 and 5 m depth at low tide.…”