Adding insult to injury: Ship groundings are associated with coral disease in a pristine reef

Abstract

In 2013, the remote Tubbataha Reef UNESCO World Heritage Site, in the western Philippines, experienced two ship groundings within four months: the USS Guardian (USSG), a US military vessel, and the Min Ping Yu (MPY), an illegal Chinese fishing vessel. Here, we present the results of coral disease assessments completed two years post-grounding and recovery patterns monitored annually within these grounding sites. Site assessments were undertaken in three distinct zones: ‘ground zero’, where reef was scoured to its limestone base by direct ship impact; the ‘impact border’, containing surviving upright but damaged, abraded and fragmented colonies injured during ship movement; and undamaged ‘control’ sites, remote from the ship groundings but located on the same atoll. Coral diseases were dominated by white syndromes, and prevalence was an order of magnitude higher within the impact border zones than within the other zones two years after the events. Hard coral cover has steadily increased at a mean rate of 3% per year within the scoured USSG site at a rate comparable to control sites. In contrast, recovery has been negligible within the rubble-dominated MPY site, suggesting that substrate quality strongly influenced recovery processes such as recruitment, as larvae do not survive well on unstable substrates. Long-term recovery trajectories from these two grounding events appeared strongly influenced by movement of the ship during and after each event, and site-specific wave-influenced persistence of rubble and debris. High prevalence of coral disease among damaged but surviving colonies two years post-grounding suggested long-term impacts which may be slowing recovery and creating localized pockets of higher persistent disease prevalence than that of the surrounding population.

The role of predators in coral disease dynamics

“…Damage by SCUBA divers may also increase the prevalence of coral disease (Lamb et al 2014) as well as increase predation by D. cornus and, ultimately, coral mortality (Guzner et al 2010). Similarly, physical damage by storms (Brandt et al 2013) and ship groundings (Raymundo et al 2018) appear to increase disease prevalence and may be linked to corallivorous snail aggregations (Knowlton et al 1990;Bright et al 2016).…”

Impacts of a shallow shipwreck on a coral reef: A case study from St. Brandon's Atoll, Mauritius, Indian Ocean

“…The initial damage caused by shipwrecks are often physical by crushing coral and other invertebrates, thereby possibly affecting topographic complexity (Precht et al, 2001). Outbreaks of coral diseases are also associated with shipwrecks (Raymundo et al, 2018). Chemical pollution occurs from the ship's fuel, cargo, and structure, influencing the ecology and toxicology of the surrounding reefs (Barrett, 2011).…”

Depth‐independent phenotypic variation of massive Porites coral color morphs

“…All colonies with some portion of colony surface area within the belt were included. Each colony was assigned to a size class based on its maximum diameter (1: 1–10 cm, 2: 11–30 cm, 3: 31–60 cm, 4: 61–100 cm, and 5: 1–2 m, 6: >2 m) (Raymundo et al., 2018). Partial mortality of a coral was defined as the area of bare skeleton without evidence of live tissue and was visually quantified and classified using semi‐quantitative binning ranging from 0 to 6 (0: no bare skeleton, all live tissue; 1: 1%–10% bare skeleton, 2: 11%–25% bare skeleton, 3: 26%–50% bare skeleton, 4: 51%–75% bare skeleton, 5: 76%–99% bare skeleton, 6: all bare skeleton, no live tissue).…”