Bioindicators of changes in water quality on coral reefs: review and recommendations for monitoring programmes

Abstract

Effective environmental management requires monitoring programmes that provide specific links between changes in environmental conditions and ecosystem health. This article reviews the suitability of a range of bioindicators for use in monitoring programmes that link changes in water quality to changes in the condition of coral-reef ecosystems. From the literature, 21 candidate bioindicators were identified, whose responses to changes in water quality varied spatially and temporally; responses ranged from rapid (hours) changes within individual corals to long-term (years) changes in community composition. From this list, the most suitable bioindicators were identified by determining whether responses were (i) specific, (ii) monotonic, (iii) variable, (iv) practical and (v) ecologically relevant to management goals. For long-term monitoring programmes that aim to quantify the effects of chronic changes in water quality, 11 bioindicators were selected: symbiont photophysiology, colony brightness, tissue thickness and surface rugosity of massive corals, skeletal elemental and isotopic composition, abundance of macro-bioeroders, micro-and meiobenthic organisms such as foraminifera, coral recruitment, macroalgal cover, taxonomic richness of corals and the maximal depth of coralreef development. For short-term monitoring programmes, or environmental impact assessments that aim to quantify the effects of acute changes in water quality, a subset of seven of these bioindicators were selected, including partial mortality. Their choice will depend on the specific objectives and the timeframe available for each monitoring programme. An assessment framework is presented to assist in the selection of bioindicators to quantify the effects of changing water quality on coral-reef ecosystems.

Conditions of coral communities in the Gulf of Thailand: a decade after the 1998 severe bleaching event

“…A long term monitoring program should be effectively implemented at unhealthy communities in the Gulf of Thailand in order to examine degradation trends or natu ral recovery processes (Cooper et al 2009;Sutthacheep et al 2009). Degradation of coral reefs is frequently associated with changes in community structure where macroalgae become the dominant benthic component (Done 1992;McManus and Polsenberg 2004;Norstrom (Sudara et al 1994).…”

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

“…It also highlights the need for monitoring at a higher temporal resolution that may help to better predict relationships between water parameters and benthic biota and structure, helping to better understand drivers of coral reef status. Cooper et al (2009) reviewed coral reef bioindicators and identified a number that were useful as timeintegrated measures of water quality, responding from minutes to months to years. Knowledge of ecological and physiological response times of organisms and communities helps to interpret relationships to different water quality parameters.…”

“…Because of this high variation, it is often difficult to identify trends and drivers of coral reef status or health and to communicate to managers and politicians the needs for action (Jameson et al, 2001). There is also often a discrepancy among response times of water quality and benthic variables, which makes monitoring, analysis and interpretation of the data more difficult (Cooper et al, 2009). Additionally, long-term monitoring programs are costly and work intensive.…”

Establishing microbial baselines to identify indicators of coral reef health

“…Biological indicators are a wellestablished monitoring tool for estuarine and freshwater ecosystems 25,26 and also find application in coral reef ecosystems 27 systems, which has led to holistic sampling efforts to establish the first microbial baselines for soils and marine environments. We argue that the establishment and ongoing assessment of such microbial baselines will be crucial to understanding microbial dynamics in response to broad ranging anthropogenic impacts.…”