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By Guest Writer, Marlene Severino: Marlene is an undergraduate student in the Wildlife and Conservation Biology program at the University of Rhode Island where she is focused on marine life and ocean conservation. She has worked closely with conservation programs including the New England Aquarium and Rhode Island’s Save the Bay organization. She has also participated in the Global FinPrint research project.

Campbell SJ, Darling ES, Pardede S, et al. Fishing restrictions and remoteness deliver conservation outcomes for Indonesia’s coral reef fisheries. Conservation Letters. 2020;13:e12698.

A healthy reef is a happy reef

Summer is here! The trees are green, the birds are singing, and the beaches are packed with people attempting to social distance themselves. But, what if you walked outside and didn’t hear the birds, or couldn’t find shade to take a break from the beaming hot sun because there were no trees? Well, you would be right to think something was wrong because a healthy ecosystem is one full of life. Coral reefs are no different. They too need an abundance of life, or biomass, to remain at the height of biological vigor (Fig. 1), and this has a direct and immediate impact on the human populations that depend on the ocean for food. Although stopping fishing activity cold turkey may seem like a good idea, there are communities in Indonesia that have no other means of food, and finding a balance between fishing and conservation is imperative to the longevity of these communities. In fact, 83% of the world’s fished reefs contain less than half the biomass that is required, and international coral reef management has proposed targets of 300 to 1000 kg of biomass per hectare (picture 1000 fluffy puppies on a football field) as a goal for local governments.

Figure 1. Coral reef food web and trophic levels. Producers make biomass and store the sun’s energy for use throughout the ecosystem. (

Send in the scientists!

Recently, a team of researchers led by Dr. Emily Darling of the Wildlife Conservation Society conducted the first national assessment of Indonesia’s coral reef health. Their goal was to show how the biomass of various coral reef locations is linked to specific management controls and reef zonations to help Indonesia reach their goal of expanding their marine protected areas to 32.5 million hectares by 2030. Indonesia has the highest number of reef fishers and is also one of the top fish producers. In research done between 2005 and 2016, scientists aimed to assess the biomass targets placed throughout Indonesia to quantify the abundance of fish in heavily fished reefs compared to that in more remote areas. This was done by using underwater visual surveys of 622 coral reefs from the colored locations shown in Figure 2 within different reef zonations such as the reef slopes, crests, flats, and lagoons in Indonesia.

Figure 2. Map of the 622 coral reef survey sites. Colors and text indicate the 17 broad geographic regions surveyed. Bubble size indicates the average biomass of each region. (Campbell et al., 2019)

At each location the team recorded the abundance and size of each species, and placed them into groups depending on their trophic role. The surveys were also taken from the following management categories: no take zones, gear restricted, open access, and secluded sites that are more than 9 hours away from the human population. The data collected were then analyzed using RDA, redundancy analysis, which summarizes the average biomass among five trophic groups.  The first group being herbivore-detritivores which eat plants and dead material. The second trophic group are the meat and plant eaters known as omnivores. Planktivores eat tiny ocean drifters called plankton. Invertivores consume invertebrates or organisms that lack a backbone. Piscivores are known for ingesting mostly fish. Linear mixed effects regression models were used to evaluate the total biomass and the biomass of each trophic group.

Figure 3. Total reef fish biomass for each of the four management types evaluated. (Campbell et al., 2019)

Humans DO disturb the peace

As expected, results confirm that human disturbance has a massive effect on ecosystem biomass (Fig. 3). Remote sites contained an amazing 4.6 times higher total biomass than open access sites. While less than the target, coral reef locations with gear restrictions also contained a biomass 1.4 times greater than open access sites. As expected, heavy human-populated areas with easy accessibility to coral reef sites exhibited significantly less biomass than any of the other site types. Even reefs that were in deeper waters showed a high biomass. So, as they say, the proof is in the pudding. Less human contact means these ecosystems are able to flourish.

Finding the balance between humans and nature

Results showing the biomass of remote sites and gear restricted areas prove that both management and remoteness play a major role in a healthy ecosystem. To let these ecosystems flourish, a stronger community compliance is needed throughout Indonesia and this starts with adjusting their policies and making sure to reinforce them. Secondly, it suggests the possibility of granting local farmers managed access to resources for long term sustainability. Larval dispersion is common on reef sites so creating large enough marine protected areas is also an idea that should be explored in the future as to protect offspring as well as adult organisms that are capable of reproducing. Precautionary protection of remote coral reef sites should also take effect. Areas with a moderate or high population should put in place more control on the selective gear.

Indonesia’s goal of increasing the coverage of marine protected areas to 32.5 million hectares by 2030 can be accomplished if there is a 500kg/ha guideline put in place. Proper management of fishing is necessary to maintain coral reef ecosystems as well as diversity of species in the ocean. This means actively working towards this change to be able to find the correct balance to be able to coexist with the marine environment. Strong and well thought out conservation management is the best step in the right direction to achieve these goals and ensure the health of this beautiful ecosystem in the years to come.

Zak Kerrigan
I am completing my doctorate at the Graduate School of Oceanography at the University of Rhode Island where I study the community structure and evolution of deep-sea sediment bacteria. I have also been an adjunct professor at the Community College of Rhode Island for two years. I earned a B.S. in Aerospace Engineering from the University of Miami and spent 12 years in the US Navy driving submarines before coming back to grad school.

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