Species

The Dutch Windward Islands (St. Eustatius, Saba, St. Maarten) support a collective herpetofauna consisting of two frogs (both introduced), six turtles (one introduced, one of uncertain origin, and four sea turtles, of which three are known to nest in the islands), 15 or 16 lizards (depending on whether the iguanas of Saba are a species distinct from Iguana iguana), and three snakes (one introduced). Although politically united, the islands are distinct biogeographic entities and binary similarity indices for the herpetofauna are 0.38 for St. Eustatius/Saba, 0.35 for St. Eustatius/St. Maarten, and 0.20 for Saba/St. Maarten (with values varying only little when the introduced species are included). Only three species, Eleutherodactylus johnstonei, Hemidactylus mabouia, and Thecadactylus rapicauda, are found on all three islands. Species given formal recognition as being in need of protection include the sea turtles (listed in CITES appendices and the IUCN Redlist), Geochelone carbonaria (CITES), Iguana delicatissima (CITES and IUCN), Iguana iguana (CITES), and two species of Alsophis (IUCN). Other species of conservation concern include two species of Ameiva, both of which are restricted to areas of considerable human activity on islands where mongooses (Herpestes javanicus) are established, and Mabuya sp., which may be extirpated on St. Maarten. Three factors largely responsible for the status of these species are: (1) large size and economic value (turtles and iguanas), (2) persecution by people who fear them (snakes), and (3) diurnally active, terrestrial, and vulnerable to predation by mongooses (snakes, Ameiva, Mabuya). Non-governmental organizations on each island are largely responsible for conservation and related educational efforts. Specific recommendations for each island are listed.

We compared catches of settlement-stage reef fishes in light traps attached to underwater speakers playing reef sounds with those of silent traps during a summer recruitment season at Lizard Island, Great Barrier Reef, Australia. Of the total 40191 reef fishes we collected, significantly more (67%; Wilcoxon and Binomial tests: p< 0.001) appeared in the traps with broadcast reef noise. Traps deployed with speakers consistently caught a greater diversity of species (Wilcoxon test: p< 0.001, total 81 vs 68) than did silent traps. This study provides a clear demonstration that the settlement-stages of a broad range of families of coral reef fishes are attracted to reef sounds

Abstract:

Based on the goals set forth in the Dutch Biodiversity Policy Programme, The Netherlands has a traditionally strong commitment to protect biodiversity and marine mammals both internationally and in its own national and Kingdom waters. Last year the responsible ministry, namely the Netherlands Ministry of Economic Affairs, Agriculture and Innovation (EL&I), developed a management plan for the biological resources of the recently declared Dutch Caribbean Exclusive Economic Zone. The Dutch Caribbean EEZ was formally declared on June 10, 2010, and amounts to more than 90,000 km2 of diverse tropical marine habitats. One of the key ambition coming forth from that plan was to develop a Dutch Caribbean Marine Mammal Sanctuary (MMS). This report provides the necessary review and background on which to base such an endeavour.

Our updated review establishes beyond doubt that the Dutch Caribbean EEZ has a rich and diverse marine mammal fauna which merits more extensive protection. Even though the fauna is only poorly known, based almost exclusively on incidental sightings and strandings, it amounts to a minimum of 19 marine mammal species, and possibly up to more than 30. Without exception, all documented species appear on protected species lists of one or more treaties ratified by the Kingdom, and/or its constituent countries. Large differences are apparent between the leeward and windward sectors of the Dutch Caribbean EEZ, both in terms of species composition and conservation issues. Throughout the region, cetaceans are playing an increasingly important role in island economies as an important natural attraction for eco-based recreation and tourism, and in this respect the Dutch Caribbean also possesses major potential.

We here propose the establishment of a MMS as the cornerstone to sustainable conservation and management of these charismatic animals. Ecological arguments for the establishment of habitat protection by means of the concept of sanctuaries are outlined, as are the many environmental issues that would eventually need to be addressed within the sanctuary.

Favourable pre-conditions for the establishment of a MMS in the Dutch Caribbean include the fact that

• a) all cetaceans are already have a legal status in the Dutch Caribbean EEZ which calls for actual protection,
• b) the most deleterious fishing practices are already significantly limited and controlled within Kingdom waters,
• c) the key enforcer, namely the Coastguard, is already strongly present (largely due to other reasons),
• d) the islands generally have a strong tradition of marine protected areas in coastal habitat,
• e) the incremental costs for research and enforcement needed to establish a sanctuary is modest,
• f) public support is high, thanks to the generally high level of development and awareness of the public,
• g) indigenous fishery practices do not conflict with cetacean conservation, and
• h) whale watching interests are only in their infancy.

Steps to establish a Marine Mammal Sanctuary (MMS) should include:

• Legal designation of the sanctuary is the first and most important step that provides the framework for all broader (international cooperation) and in-depth (knowledge and conservation development) initiatives.
• Once established, the fuller implementation of an MMS should be seen as a gradual process, involving development of knowledge, policy, rules and regulations, as well as public and stakeholder participation

Management Recommendations:

The following key action points are proposed to establish a Marine Mammal Sanctuary:

• a) Legal designation of the EEZ (one or both sectors) as MMS, along with establishment of legal guidelines for interacting with cetaceans (whale watching).
• b) Establish bonds of cooperation with sister sanctuaries in the region (France, USA, Dominican Republic), (e.g. regional stranding and sightings data network).
• c) Conduct baseline quantitative surveys of cetacean distribution and assessments in light of sources of deleterious sound sources and risks of vessel strikes.
• d) Review and adapt existing national and insular legal frameworks to improve these, preferably by developing separate and standardized marine mammals legislation.
• e) Develop information systems to promote the development of a whale (cetacean) watching industry.
• f) Train and equip marine parks and island veterinarians to conduct elementary autopsies and collect basic stranding specimens for analysis of causes of mortality, contamination levels and genetics, and link them to international academic institutions who will accept and analyse the specimens in regional context.
• g) Develop species action plans (e.g. humpback).
• h) Conduct cetacean surveys and management reviews every 5 years to assess marine mammal status and conservation progress.

Management of many species is currently based on an inadequate under- standing of their population dynamics. Lack of age-specific demographic information. particularly for long-lived iteroparous species. has impeded development of useful models. We use a Lefkovitch stage class matrix model. based on a preliminary life table developed by Frazer (1983a), to point to interim management measures and to identify those data most critical to refining our knowledge about the population dynamics of threatened log- gerhead sea turtles (Caretta caretta). Population projections are used to examine the sen- sitivity of Frazer's life table to variations in parameter estimates as well as the likely response of the population to various management alternatives. Current management practices appear to be focused on the least responsive life stage. eggs on nesting-beaches. Alternative protection efforts for juvenile loggerheads. such as using turtle excluder devices (TEDs). may be far more effective. 

The marine exotic species of the Dutch Caribbean are less well-known than its terrestrial exotics. So far, only 27 known or suspected marine exotic species, some of which are also invasive are documented for one or more islands of the Dutch Caribbean. Four of these were documented only once or were only present for a certain period of time and are no longer present. Six of the species are marine epidemic diseases. As very little is known about these diseases, they might actually be native, but based on the literature and their ecological signature we regard them as special cases of invasive species.

In addition to these documented species, 76 other exotic species that have already been observed elsewhere in the Caribbean may already be present or can be expected to arrive in the Dutch Caribbean in the near future. The marine communities of the Dutch Caribbean have suffered major changes based on a handful of marine exotic and/or invasive species, particularly in the special case of (opportunistic) pathogens. In certain cases experience shows that after decades, the affected systems/species may show slow signs of recovery from initial impacts (e.g. the green turtle fibropapillomas), while in other cases the impact may be long-lasting and recovery doubtful (e.g. sea fan mortality).

Compared to terrestrial exotic species, eradication and control have been proven difficult or impossible for marine exotics. Therefore, management practices aimed at controlling unwanted species introductions should focus on preventing the arrival of such species by ships-- that transport exotics in their ballast water or as fouling communities on their hulls-- and (accidental) introductions from aquaculture or the aquarium trade. Busy harbors can be expected to be the areas where most marine exotics likely establish first.

Because of dispersal of marine exotics is facilitated by ocean currents, local approaches to prevent their arrival or reduce their numbers will be less effective compared to similar efforts for terrestrial species. In the case of marine exotics and invasives, it is paramount that prevention, control and management efforts should be regionally integrated. We conclude this report by listing a number recommendations on how to develop effective management approaches with which to address the impacts and risks associated with marine exotic species.

This research is part of the Wageningen University BO research program (BO-11-011.05-004) and has been financed by the Ministry of Economic Affairs, Agriculture and Innovation (EL&I) under project number 4308202004.

Management Recommendations:

• The boundaries of the WSNP should be expended to include all the salinas included in this survey. This expansion will not only benefit the waterbirds but every other native species of flora and fauna as well.
• Pursue the designation of Salina Frans as a Ramsar site for Bonaire, given its importance as a habitat for both terrestrial and waterbirds.
• Keep collecting data for long term monitoring programs. It is fundamental for the proper management of our natural resources.
• Provide more training for the staff involved in the counts.
• Install permanent depth gauges in all the salt flats being monitored.
• Conduct more scientific research for a better understanding of the ecological functions of the salinas as a habitat for water birds
• As resources or time become available, start a monitoring program for the nesting seasons of our resident waterbirds. 

Background:

Located in the Dutch Windward Islands, Saba Bank is a flat-topped seamount (20–45 m deep in the shallower regions). The primary goals of the survey were to improve knowledge of biodiversity for one of the world’s most significant, but little-known, seamounts and to increase basic data and analyses to promote the development of an improved management plan.

Methodology/Principal Findings:

Our team of three divers used scuba to collect algal samples to depths of 50 m at 17 dive sites. Over 360 macrophyte specimens (12 putative new species) were collected, more than 1,000 photographs were taken in truly exceptional habitats, and three astonishing new seaweed community types were discovered. These included: (1) ‘‘Field of Greens’’ (N 17u30.6209, W 63u27.7079) dominated by green seaweeds as well as some filamentous reds, (2) ‘‘Brown Town’’ (N 17u28.0279, W 63u14.9449) dominated by large brown algae, and (3) ‘‘Seaweed City’’ (N 17u26.4859, W 63u16.8509) with a diversity of spectacular fleshy red algae.

Conclusions/Significance:

Dives to 30 m in the more two-dimensional interior habitats revealed particularly robust specimens of algae typical of shallower seagrass beds, but here in the total absence of any seagrasses (seagrasses generally do not grow below 20 m). Our preliminary estimate of the number of total seaweed species on Saba Bank ranges from a minimum of 150 to 200. Few filamentous and thin sheet forms indicative of stressed or physically disturbed environments were observed. A more precise number still awaits further microscopic and molecular examinations in the laboratory. The expedition, while intensive, has only scratched the surface of this unique submerged seamount/atoll. 

Findings:

Combining the findings of this study with that of other studies, the authors conclude that the coral assemblage on the Saba Bank is diverse and healthy; it is representative and typical of those found elsewhere in the Caribbean.

Coral Richness

• A total of 43 species were documented.
• There were no significant differences in coral composition amongst bottom types or depth classes.
• There was a significant difference between sites near and far from the platform edge. The number of coral species observed ranged from 0 and 1 in algal dominated habitats to 23 at a reef habitat on the Bank’s southern edge.
• Coral species richness was higher on reef dominated areas as opposed to algal dominated ones.

Coral Condition

• Bleaching was evident at 82% of the sites assessed with 43 colonies bleached.
• Only three coral colonies were observed to have disease.
• Five reef sites had stands of Staghorn Coral (Acropora cervicornis), a critically endangered species on the IUCN Red List.
• No physical damage consistent with anchor usage or sand scour from shipping activity was noted at any of the sites assessed.

Management Recommendations

1. Immediate action is necessary to protect the diverse coral reef habitats documented.
2. The five healthy stands of staghorn coral (A. cervicornis) and their surrounding should be given highest priority for full protection in the zoning use plan under development (in consultation with all stakeholders).
3. More information is needed on the Saba Bank to create a comprehensive zone use plan. For example, more sites need to be studied so as to get a more comprehensive coverage of the bank’s coral composition.