Chemical Pollution on Coral Reefs: Exposure and Ecological Effects

Abstract

In this chapter we review the effects of anthropogenically derived chemical pollutants on tropical coral reef ecosystems. A wide range of compounds, including pesticides, trace metals and petroleum hydrocarbons enter reef systems through various pathways and affect different reef species and/or life history stages. Tools for evaluation of chemical stress on coral reefs consist of molecular, biochemical, physiological and ecological bioindicators, providing information at organismal or community levels. This chapter collates and assesses available information on different chemical stressors in the marine environment and the effects on reef-building corals. Ecological effects from chemical stressors are strongly dependent on exposure characteristics. Three probable pollution scenarios are discussed and their individual properties evaluated. Short-term, pulse-like pollution events including oil spills or antifoulant deposition through ship groundings often have a direct and severe impact upon multiple trophic levels of the system. However, these events are typically localised and possibly irrelevant on an ecosystem-wide scale. In contrast, recurring pollution events such as input from river floods or chronic pollution from land runoff (e.g. sewage treatment effluent or herbicides), may exert subtle effects on lower trophic levels of the system, affecting species fitness and driving adaptation. Effects from recurring or chronic pollution are more likely to combine and interact with other environmental factors, but remain poorly understood. Over time, chronic sub-lethal stress may decrease resilience of reef organisms to other forms of environmental stress like elevated sea surface temperatures and ocean acidification. CORAL REEF ECOSYSTEMS AND SYMBIOTIC PRODUCTION Coral reefs are biogenic structures that often contribute significantly to the seaward section of tropical shorelines, buffering the coast from wave action and erosion [1]. Coral reefs are among the most biologically diverse and productive systems in the world and many coastal communities depend upon these economically and culturally important ecosystems as a source of income or resources. Coral reefs are crucial to tropical fisheries and tourism and provide many island populations with primary building materials. Reef-related tourism alone generates vast revenues in some parts of the world. For example, in the 1990s, an estimated $140 billion was generated by Caribbean reefs annually [2]. The ecological value of coral reefs is also enormous. There are over 600 species of calcifying corals, and these contribute directly to the habitat of thousands of species of tropical fish, algae and invertebrates. The physical protection offered by coral reefs enables formation and persistence of associated ecosystems such as seagrass beds and mangrove forests, allowing for the existence of essential habitats, hatching grounds and fisheries [3]. These ecosystems are in turn crucial for the reefs, as they play an important part in the sustenance of the marine foodweb by p...

The history, biological relevance, and potential applications for polyp bailout in corals

“…Numerous environmental conditions have been identified as detrimental for coral colonies resulting in the formation of stress responses; these include higher than usual sea surface temperatures (Hoegh-Guldberg, 1999;Hughes et al, 2017;Lesser, 1997), sedimentation (Anthony & Larcombe, 2000;Weber et al, 2006;Wiedenmann et al, 2013), shifts in nutrient availability (Morris et al, 2019;Wiedenmann et al, 2013), pollution (Negri et al, 2012), ocean acidification (Hoegh-Guldberg et al, 2007), and epizootics (Harvell et al, 2007). These stressors affect almost all life stages of scleractinian corals, resulting in a great variety of adaptations in coral life-history traits with associated plasticity of responses.…”

Morphological, elemental, and boron isotopic insights into pathophysiology of diseased coral growth anomalies

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