Under stressful conditions, such as during unusually warm periods or after severe storms, corals can be more susceptible to disease and other sources of mortality. In some instances, restricting activities or closing reef areas can be an important strategy for managers to minimize impacts on reefs during temporary increases in environmental stress or during periods of recovery.
Activities that might be the focus of additional management effort during times of high coral stress include:
- Wastewater discharge
- Physical contact from divers or anchors
- Fishing (especially of herbivores)
Where suitable regulations exist, managers can establish temporary site closures or exclusion zones if they believe that this will improve the outcomes for corals. However, there are a number of important considerations when contemplating site closures. Managers should recognize the potential impact on tourism businesses and fishing communities, as well as the implications for the relationship with stakeholders. Social impacts can be minimized and compliance maximized through engagement strategies aimed at helping stakeholders understand the situation and participate in designing management responses.
Recognizing When Corals Need Help
The first step in helping corals through stressful periods is recognizing when they are under pressure. Stressful conditions can be indicated by changes in certain environmental parameters, such as elevated temperatures, unusual cold spells or unusually high turbidity. There can also be more direct indications that corals are under stress, such as increases in occurrence of disease or bleaching. Bleaching can be a particularly important sign, as it is both readily observed and a reliable general indicator of stress (i.e., corals often bleach when exposed to unusually high temperatures, unusually low temperatures, pollutants, decreased salinity, etc). Monitoring programs designed to provide early warnings of stressful conditions or signs of stress can be crucial to identifying when corals might benefit from additional management efforts.
Reducing Physical Damage Through Best Practices
During stressful conditions, reef managers might consider measures to reduce the risk of physical damage to corals, especially at high-value or heavily-used sites. Ideally, this would be achieved through best practice approaches to diving and anchoring. These include siting dive-training exercises over sandy areas (rather than over corals), educating divers (including underwater photographers) about the importance of good buoyancy and no-touch diving and in-water supervision of divers by experienced dive guides to protect reef health. Installation of surface rest stations can help keep snorkelers safe and reduce the need to stand on the reef if they become tired or anxious.
Additional moorings, even temporary ones, can help boat operators secure their vessels without causing anchor damage. Boat captains should also be reminded of the importance of anchoring in ways that ensure anchor and tackle do not contact the reef when moorings are not available. A range of resources exist to assist establishing best practice diving and boating, including those developed by the Great Barrier Reef Marine Park Authority and Coral Reef Alliance.
Diving Best Practices — to minimize damage to coral
- Avoid all contact with corals and other marine life
- Never chase or ride marine animals
- Take nothing living or dead out of the sea, except recent garbage
- Maintain good buoyancy control
- Practice good finning technique and body control
- Ensure all equipment is well secured so that it cannot drag or snag on corals
- Only handle, manipulate, or feed marine life under expert guidance, never just to take photographs
- Avoid using gloves and kneepads in coral reef environments
Anchoring Best Practices
- Examine the area before anchoring to find the best location
- Anchor in sand or mud away from corals
- Anchor away from fragile or sensitive areas including bird and turtle nesting areas, Indigenous heritage sites and shipwrecks
- Anchor your boat a safe distance away from other boats
- Look out for the safety of people in the water when dropping your anchor
- Never wrap the anchor rope or chain around bommies or large coral heads
- If anchoring ashore, carefully place the anchor to minimize shore and coastal damage
- If anchoring overnight, anchor before nightfall and double check the swing room
- Carry enough chain and line for the depth you want to anchor in
- Use the correct anchor for your situation and environment
- Retrieve the anchor when the line is vertical
- If the anchor is caught on the reef, free it by hand wherever possible
- Do not force the anchor free by motoring forward
- Use only as much chain as you need to hold the vessel, without compromising safety
- Keep watch to make sure the anchor isn’t dragging
- Motor towards the anchor when hauling it in
Preventing Wastewater Discharge
Managers can also work with vessel operators and land-based facilities to minimize discharge of wastewater near corals during periods of environmental stress. For vessels, this can take the form of offloading wastewater only at shore-based facilities (where they exist) or discharging into the marine environment far from coral reefs (i.e., in deep water). For land-based facilities that discharge into the marine environment, such as sewage treatment plants or settlement pond overflows, there might be options for holding wastewater until conditions have eased for corals, or at least discharging when mixing potential is greatest (large tidal flows, for example).
Coral reef managers are likely to need to work with other agencies when it comes to wastewater management, but through cooperative approaches, there is often scope to raise awareness of best practice approaches or to enact and enforce relevant legislation.
Protecting Herbivores During Recovery Phase
Healthy coral reefs are more likely to be able to bounce back from acute incidents (such as bleaching events that cause mass mortality, or severe storms). However, the recovery process can be significantly slowed if key processes, such as herbivory, are at reduced levels. Temporary bans on collecting herbivores at reef sites that have suffered impacts can help with reef recovery, and may be considered by managers as part of a recovery assistance strategy. However, bans may need to be in place for several years, at least until damaged reefs have passed through the early stages of recovery.