Findings:

The main conclusion from this study is that at the moment tourists and locals use Lac Bay and its catchment area at levels and in ways that are not sustainable.

Recreational use:

• Recreational use is concentrated on and around the Sorobon Peninsula. The major activities are beach and sports-related (sunbathing and windsurfing). The main water based activities are windsurfing and swimming/wading.
• The social carrying capacity for the present kind of visitor and present kind of usage begins to become an issue around 250 beach visitors. Average visitor numbers on cruise days is 359 (highest is 760) and on weekends is 260.
• There is a large difference in visitor numbers between cruise days and non- cruise days, with cruise days having the highest.
• Awareness of Lac Bay’s regulations and zoning plan is low, resulting in certain activities taking place in sensitive zones.

Land use:

• Fresh water surface-flow to the bay is affected by approximately 54 dams or more, and groundwater flow by many (uncounted) wells
• 213 kunukus (farms on Bonaire) are present in Lac Bay and its catchment area.

Livestock densities within the natural areas surrounding Lac Bay are not sustainable. They exceed the ecological carrying capacity of the area.

Management Recommendations

- Develop and implement a set of measures that can be used to preserve and enhance the Lac visitor experience in accordance with social carrying capacity.

- Develop sunbathing and water sport possibilities elsewhere on Bonaire to distribute user densities from Lac Bay.

- Develop and implement a set of measures that can be used to preserve and enhance the natural values of Lac Bay.

• Improve the implementation of the zoning plan.
• Organize several facilities at Sorobon more properly.
• Create a visitor centre at Sorobon.
• Reduce livestock densities in the Lac Bay catchment area.

Key recommendations for further study:

• Research on up to what extend tourists facilities are contributing to the eutrophication at Lac.
• Research on the effect of sunscreen on coral bleaching at Lac.
• Further research to obtain a clear overview of land use in Lac’s catchment area.

Findings

The main issues that Lac Bay faces were identified as follows:

1. Filling-in of Lac and reduced water circulation. Over-grazing by extensive livestock husbandry as well as non-sustainable land-use practices (e.g. barren fields) has resulted in an accelerated infilling of the bay with sediment, which hampers water circulation and causes mangrove die-off. This has lead to a gradual reduction of the effective nursery and habitat surface of the bay over the last decades.
2. Increase in uncontrolled recreational pressure. The Lac ecosystem has been modified or altered by construction of roads, the building of hotels, subterraneous nutrient enrichment by untreated sewage and more. Trampling is causing an important decrease in sea grass bed coverage in the bay. Endangered species such as turtles and nesting birds are vulnerable to human disturbance (Lac is intensively used for various kinds of recreation).
3. Litter contamination. Marine litter washed in from the open ocean and abandoned fishing lines in the deeper parts of Lac are big issues.
4. Algal blooms. While the outer reef is in very good health, many of the inner reef’s corals, gorgonians and sponges are being overgrown by the crustose calcareous alga Ramicrusta sp. This may cause a serious decline in living corals inside the bay.

Management Recommendations:

The highest priority is to start habitat restoration.

Direct enforcement of existing and new legislation is crucial as well as a permanent presence of one or more officials.

Filling-in of Lac and reduced water circulation

• Tackle the livestock overgrazing problem in the whole watershed.
• Regularly open up the former channels to the rear areas of the mangroves and re-establish circulation and water quality.
• Remove filled-in sediments and reforest with red mangroves in the rear stagnant areas of Lac so as to re-establish mangrove and fish nursery habitat.

Address increase in uncontrolled recreational pressure

• Set upper limits for the various users.
• Strictly limit public access to seagrass areas using a combination of zoning, demarcation and enforcement.
• Upgrade the visitor facilities designed to limit or steer user impact towards low sensitivity areas.
• Monitor the human use of the bay.
• Assess Lac’s current bird use and their vulnerability to disturbance.

Litter contamination

• Conduct regular cleanups with volunteers and monitor litter densities.
• Limit and regulate fishing inside of Lac.
• Conduct PAH  (polyaromatic hydrocarbon) studies of the water in Lac.

Algal blooms

• Periodic annual monitoring of enteric bacterial presence at high risk locations.
• Install a monitoring program to assess the nutrient situation in Lac at several locations.
• Continue monitoring of coral overgrowth by Ramicrusta sp. 

Lac Bay, Bonaire is the most important mangrove and seagrass area of Bonaire and has been undergoing steady ecological decline in the last decades. Based on an initial assessment of conservation management issue and potential solutions, as, conducted by IMARES in June 2010, the Dutch Ministry of Agriculture, Nature and Food Quality (LNV) asked IMARES to return to Bonaire to work with Stinapa Bonaire to choose narrower priorities and jointly make a short-list of topics as a working document for cooperation and action. In the beginning of September, site visits and discussions were held in Bonaire with the manager of Lac Bay and various stakeholders to identify and agree on priority issues for action. This working report gives the results of that visit.

Four action spear point projects were identified, based on urgency and feasibility based on local Bonaire and Dutch IMARES expertise. The projects are as follows:

1. Mangrove restoration demonstration pilot study
The basic objective is to reestablish water depth and tidal connection in high marsh salt areas that have resulted from infilling with sediment, and restore them as effective mangrove and low marsh fish nursery habitats. By collecting baseline data before the restoration activities take place, it will be possible to monitor and compare and assess changes in fauna and flora at the restoration sites and hence evaluate the effectiveness of the measures implemented.

2. Baseline ecological study of the zonation of aquatic communities
The goal is to complete a scientific description of Lac’s aquatic community zonation as it exists at landscape level today. This will provide the framework against which large-scale community change and effectiveness of mitigation measures can be monitored and evaluated.

3. Recreational and land use survey for Lac Bay and its catchment area
The goal is to identify user problems and potential solutions by mapping and assessing user density and pressures in Lac

4. Study of avifaunal habitat use of Lac Bay
The goal is to identify bird habitat use problems and potential solutions by assessing habitat use of Lac by birds during the migratory season.

(A fifth project for implementation by Stinapa and Dienst LVV was identified)
5. Lac mangrove channel clearing project
Re-establish water flow from the Bakuna dam to Lac using a pipe system.

The Lac mangrove channel clearing project of Stinapa was reviewed and judged to be valuable and important. The baseline study of zonation of aquatic communities (project 2) is urgently needed in this respect to allow short and long-term evaluation of this project which need to become a structural part of Lac Bay management. Routine mangrove channel maintenance was identified as ideal work for involvement of Bonaire youths and volunteers, to rekindle public involvement in caring for Lac and its rich natural and cultural-historical heritage. 

Management Recommendations:

A project plan is presented by which all four projects can be delivered by December 2012. These projects can count on government and broad community support. In this all, Stinapa indicated to be willing to provide basic free lodging to interns and scientists at their science accommodations at the entrance of Washington-Slagbaai National Park. The ability and willingness of IMARES to recruit and guide students and interns for these projects was an important selection criterion to help restrain total project costs. The action spear points will, nevertheless, require funding as well as permits from the Island Government of Bonaire. With LNV various funding options were reviewed and discussed, and the need for permits was discussed with DROB (Dienst Ruimtelijke Ontwikkeling en Beheer) Bonaire. DROB envisioned few problems with the required permits. The visit was concluded by the joint resolve to work out ways to maintain momentum and proceed towards the implementation phase.