Ecosystem Monitoring in the Ngederrak Marine Conservation Area

By Jim Haw and David Ginsburg

Originally published at ScientificAmerican.com

The Rock Islands of Palau is a unique and unmistakable site. It is not uncommon to hear comparisons between this very real place and the fictional world of James Cameron’s Pandora. Administratively, the Rock Islands lie in The State of Koror, the most populous of this thinly populated Republic. The Koror State Government is responsible for monitoring and regulating the use of The Rock Islands. They have defined six conservation zones for The Rock Islands ranging from General Use followed by Subsistence Fishing, through Preservation, Conservation, and Tourism, to the most restrictive management category, Special Management.

USC Dornsife students taking a heading at the start of a transect in Ngederrak. (Photo by Jim Haw)

Our primary focus in Palau is in support of one of these Special Management areas – the Ngederrak Marine Conservation Area. So restricted is Ngederrak that it can be used only for scientific monitoring and research, and only with the permission of the State of Koror. And for the second year, our scientific diving field course has that permission. Working closely with Ilebrang Olkeriil and King Sam, agency director and head ranger, respectively, from the Department of Conservation and Law and Enforcement, our group will assist in ongoing efforts to evaluate the effectiveness of conservation and enforcement activities in this area.

Ngederrak took an incremental route to becoming a Special Management area. In 2001 fisheries resources on this reef were heavily exploited and Koror State placed a two-year moratorium on entry and take. In 2002 the moratorium was extended to four years, after which the site was freely open for just two weeks. During this period, anecdotal catch reports suggested significant recovery of some species, and the area has been permanently closed since 2005. Long term monitoring of Ngederrak Reef provides an opportunity to follow the recovery of a heavily exploited coral reef ecosystem to a more sustainable state.

Although not the focus of our studies, Ngederrak is habitat for the Palauan dugong, which is one of the most endangered animals found living in the waters of this island nation. Indeed, the robust seagrass meadows found along the reef crest of Ngederrak clearly show the presence of these animals as typified by their feeding trails. These shy animals retreat at the sound of boats and divers, but they can frequently be see from the air in helicopter-based surveys, or by kayak.

One of the giant clam species in Ngederrak. (Photo by Jim Haw)

On-going threats to Ngederrak Reef include coastal runoff and sedimentation from sewage treatment, as well as landscape modification. Ironically, nutrient runoff may actually benefit dugongs by promoting greater productivity of seagrass on the reef crest. Ship groundings sometimes occur on Ngederrak, but so far the area of reef damaged by these events has been minimal. The crown-of-thorns sea star, a voracious predator of corals, is readily seen on the reef. Population outbreaks of this species, which are not uncommon (albeit for reasons not completely understood), pose a serious threat to the reef. Although the proximity of Ngederrak Reef aids in enforcement efforts, poaching is an ever threat to all marine protected areas, as is climate change.

Our monitoring protocol for surveying Ngederrak Reef was developed in conjunction with local scientists and fisheries managers at the Koror State Department of Conservation and Law Enforcement, with whom we share all of our data freely. Over a period of 3 days, we conduct a series of SCUBA and snorkel surveys over the whole of the Ngederrak Conservation Area (based upon coordinates generated within a GIS database maintained locally). Specifically, USC students conduct 50-m transect surveys in which they quantify and record key invertebrate and fish indicator species.

Invertebrate (sea grass bed) and fish (reef crest) indicator species quantified and recorded on Ngederrak Reef, Koror, Palau. Indicator species table from Bailey (2005).

On a typical day, each student team will perform two dive transects (30 to 40 fsw max), and up to four snorkel based transects in the reef shallows (4 to 6 fsw max). Given that we have more than two-dozen students in the water at a time a tremendous amount of data is quickly generated. On the SCUBA dives, students finish their measurements in 20 minutes or less, and with 30 to 40 minutes allotted to each dive, depending on depths and surface intervals, there is a lot of time for touring the reefs.

USC Dornsife students show their colors following a control survey on Short Drop Off Reef. (Photo by Jim Haw)

Our students have come a long way from that first weekend (~2 months ago) on Catalina Island. They are making real-time ecosystem measurements as scientific divers that will help the Republic of Palau chart a course toward more effective conservation of marine resources and biodiversity that form the linchpin of their ecotourism-based economy.

Reference:

Bailey D (2005) Methods for Assessing the Effectiveness of a MarinevProtected Area: Harvestable Invertebrate and Fish species of Ngederrak Reef, Koror, Palau. Technical report prepared by: Coral Reef Research Foundation and Koror State Department of Conservation and Law Enforcement.

Editor’s note: Scientific Research Diving at USC Dornsife is offered as part of an experiential summer program offered to undergraduate students of the USC Dana and David Dornsife College of Letters, Arts and Sciences. This course takes place on location at the USC Wrigley Marine Science Center on Catalina Island and throughout Micronesia. Students investigate important environmental issues such as ecologically sustainable development, fisheries management, protected-area planning and assessment, and human health issues. During the course of the program, the student team will dive and collect data to support conservation and management strategies to protect the fragile coral reefs of Guam and Palau in Micronesia.

Instructors for the course include Jim Haw, Director of the Environmental Studies Program in USC Dornsife, Assistant Professor of Environmental Studies David Ginsburg,, SCUBA instructor and volunteer in the USC Scientific Diving Program Tom Carr and USC Dive Safety Officer Gerry Smith of the USC Wrigley Institute for Environmental Studies.

 

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