Debrot, A.O.

Increased recruitment rates indicate recovering populations of the sea urchin Diadema antillarum on Curaçao

Abstract:

Recruitment of the sea urchin Diadema antillarum philippi, 1845 was studied on artificial recruitment panels along the leeward coast of the island of Curaçao, southern Caribbean. data were compared with historical data from the same coast that were collected before (1982–1983) and after (1984) the Caribbean-wide mass mortality of Diadema in October 1983. Average recruitment rates observed in 2005 were equal to 2.2 times lower compared to those observed before the D. antillarum die-off (1982 and 1983), but 56.5 times higher than those observed after the die-off in 1984. The increase in recruitment rates between 1984 and 2005 was 5–51 times greater than the increase in abundance of adult individuals over the same period. This suggests that despite the largely recovered recruitment rates of this important reef herbivore, unknown sources of high post-settlement mortality currently prevent a similar recovery of its adult population. 

Date
2010
Data type
Scientific article
Theme
Research and monitoring
Geographic location
Curacao

Bird communities of contrasting semi-natural habitats of Lac Bay, Bonaire, during the fall migration season, 2011

Findings:

Species richness

Species richness is highest in Lac’s mangrove thickets and salt flats. They have a two-fold higher total species richness and a fourfold higher migrant species richness compared to woodland habitats.

The coastal barrens habitats have the lowest number of species.

Composition of bird communities

63 species were recorded. 38% were resident species; 10% had resident populations but also potentially occurred as migrants, 49% were migrants and 3% were migrants that are known to possibly or irregularly breed on Bonaire.

Significant differences were found in the bird communities of the five habitats studied.

  • Migrant species are significantly more abundant among the waterbirds (herons, flamingo, waders).
  • The highest concentration of migrant birds is in the mangrove thickets and salt flat habitats
  • Migratory shorebirds and waders dominate the bird communities of Lac’s salt flat habitat.
  • The bird communities of Lac’s woodland habitats are dominated by breeding resident species.
  • Migratory passerines are not a major component of Lac’s bird fauna.

Significance of Lac

Lac Bay may be of local significance as a breeding and foraging site to the globally Near-Threatened Reddish Egret, Egretta rufescens.

Lac Bay’s mangroves seem to be of local significance as a nesting and roosting habitat for the Scaly-naped Pigeon, Patagioenas squamosa.

The Yellow-shouldered Amazon no longer uses Lac’s mangrove thickets as a roosting area. Probable causes are decrease in persecution and increase in the quality of the woodlands in many areas of Bonaire.

The Caribbean Coot is not present in Lac’s salt flat habitat. It prefers a number of freshwater locations around the island.

Lac’s number of West Indian flamingo, Phoenicopterus ruber, has grown significantly. This suggests a wider ecological shift taking place within the bay (growth of stagnant backwaters and salt flats behind the mangroves) which threatens Lac’s premier values as a mangrove and seagrass nursery area.

Management Recommendations:

Further observations to document potential egret breeding activity at Lac.

Date
2013
Data type
Research report
Theme
Research and monitoring
Report number
C164/12
Geographic location
Bonaire

The Lesser Antillean Iguana on St. Eustatius: A 2012 population status update and cause for concern

To assess the status and current population densities of the endangered Lesser Antillean Iguana (Iguana delicatissima) on the island of St. Eustatius, we spent more than 80 h searching for iguanas and covered more than 63 km of trails and tracks — but found only 22 iguanas, for an overall average of 3.7 h per iguana. Overall population density was 0.35 iguanas per hectare, which represents 0.5–1.0% of densities documented elsewhere in healthy populations. Population densities have declined across all habitats since the last assessment in 2004. The lack of nesting sites and high iguana mortalities due to anthropogenic causes were the two core factors limiting recovery of iguanas on St. Eustatius.

Our principal recommendations are to:

  • (a) Train and equip border officials to prevent potential entry of mongooses and Green Iguanas from neighboring islands;
  • (b) implement enforcement and upgrade protective legislation;
  • (c) develop and maintain new additional nesting habitat, a measure that is both easy and inexpensive; and
  • (d) establish a program to promoto "iguana-friendly" gardens as the main means of reducing cumulative mortality.

Finally, we propose the development of an in situ husbandry and breeding program to help bolster the overall recovery program, a move that would also benefit islanders by offering a relaxed setting in which they could better learn to appreciate this emblematic island species.

Date
2013
Data type
Scientific article
Theme
Research and monitoring
Geographic location
St. Eustatius

Seabird nesting on Curaçao and Bonaire, 2002.

The islands of the Leeward Dutch Antilles lie next tp each other off the north coast of Venezuela...

Date
2002
Data type
Other resources
Theme
Research and monitoring
Geographic location
Bonaire
Curacao

The marine mammals of the Dutch Caribbean: a comparison between EEZ sectors, contrasts and concerns

We here provide a synoptic overview and preliminary update of the marine mammals of the Dutch Caribbean EEZ based on 279 cetacean sighting and stranding records. The Dutch Caribbean EEZ is composed of two distinct sectors. One is centered around the leeward Dutch islands of Aruba, Bonaire and Curaçao (71,000 km2) while the other is centered around the windward Dutch islands of Saba, St. Eustatius and St. Maarten (22,000 km2). The previous principal review (of cetaceans) dating from 1998, was based on only 70 records from the leeward sector and confirmed the occurrence of some 13 species for Dutch Kingdom waters. Now, with a 4-fold increase in number of records, 19 species can be documented for the Dutch Kingdom waters (18 species in the leeward sector and 8 species in the windward sector).

The windward sector stands out for its large number of humpback whale sightings (45% of records) and may form part of its former (or current) calving grounds. This species remains relatively rare in the leeward sector (5% of records) and continues to be targeted by aboriginal fishing in its destination wintering grounds to the east, where the relict breeding population is having difficulty to rebound. The species is of growing interest to tourism in the region and urgently needs full protection from all fishing in the southern Caribbean. The leeward EEZ sector further lies down-stream from seasonal upwelling areas off Venezuela that support the largest fishery of the Caribbean. This sector stands out for its high occurrence of beaked whales and the Bryde’s whale. Marine mammal strandings are much more common here (26% of records) than in the northern sector (3% of records). Human induced mortalities (first suggested in 1974) and disturbance due to coastal tourism and recreation are key and growing concerns in the southern Dutch EEZ sector.

The marine mammal fauna of the Dutch Caribbean is evidently rich and varied but continues to suffer man-induced mortality and disturbance. Several nations, including the USA, the Dominican Republic and France, have recently established marine mammal sanctuaries in Caribbean waters. The Netherlands should consider doing the same.

Date
2011
Data type
Scientific article
Theme
Research and monitoring
Document
Geographic location
Bonaire
Saba
St. Eustatius

Additional Records and a Review of the Cetacean Fauna of the Leeward Dutch Antilles

Forty-one additional cetacean records are reported for the Leeward Dutch Antilles, expanding the list of documented records to 70 (53 sightings and 17 strandings). First records are given for the melonhead whale Peponocephala electra (Gray), such that now 13 species are confirmed for these islands. The most sighted whales are Bryde’s whale and shortfin pilot whale, whereas the most sighted dolphins are spinner and bottlenose dolphins. Most cetacean movement is upstream and towards the east/southeast. Reported strandings have been on the rise, of which 47% involved beaked whales (goosebeak whale and Antillean beaked whale)

Date
1998
Data type
Scientific article
Theme
Research and monitoring
Geographic location
Aruba
Bonaire
Curacao

First record of Fraser’s dolphin Lagenodelphis hosei for the Dutch Caribbean

A dead dolphin found on Bonaire in August 2011 is identified as adult Fraser’s dolphin Lagenodelphis hosei, a new species for the Dutch Caribbean. A first closer examination showed a collapsed lung, stomach parasite infection and abundant mouth ulceration as indications of its health status. The animal was relatively fresh and did not die very long before it was found. Like more often with stranded deep diving cetacean species within the area, remnants of crustacean were found in its beak indicating recent foraging. 

Date
2012
Data type
Scientific article
Theme
Research and monitoring
Geographic location
Bonaire

Introduced agricultural pests, plant and animals diseases and vectors in the Dutch Caribbean, with an “Alert species” list

A review of the introduced agricultural pests and animal and plant diseases and vectors for the Dutch Caribbean in which a total of 47 exotic pests, diseases, parasites and pathogens established on one or more of the Dutch Caribbean islands are listed and discussed. These include 2 species of voracious herbivorous snails, 7 species of millipedes, 8 species of invasive ants, and some 16 species of insects that infest plants. Most agricultural pests are not strongly host-specific and will typically also affect native plants and/or animals. This makes it very difficult to eradicate or control these species once established. Therefore, prevention and early eradication is key.

The most information on invasive alien pests is available for the leeward Dutch islands while the least is known for the windward Dutch islands. The principal means of entry is the importation of unsterilized soil and plant material through container shipment, import of ornamental plants and air traffic. The economic costs, both in terms of damages and control measures, as well as missed opportunities that these species cause, has not been estimated but certainly runs in the millions of dollars annually. By far the most economically costly invasive species is the yellow fever mosquito Aedes aegypti, a pest and disease vector closely associated with man. In a few cases, biological control and eradication has been successful.

Introduction of invasive pest species continues at a high rate in the Dutch Caribbean and preventive measures are urgently needed to limit future costs and risks in terms of economy and health.

Key recommendations are: a) to strongly restrict and control importation of ornamental plants, most of which can be propagated locally without risk of new introductions, b) restrict importation of unsterilized foodstuffs, c) practice tighter control and prophylactic fumigation of container shipments, d) continue strict veterinary controls on animal importations. To effectively implement such measures, will require greater awareness, supporting legislation, cooperation of customs agents and shippers and the presence of a biosecurity unit authorized and equipped to act on short notice.

Based on experiences in other Caribbean countries and existing trade patterns and taking into account which species could survive in an arid climate, it is possible to draw up a preliminary listing of “Alert” species for the Dutch Caribbean. Such a listing is a critical tool for effective prevention. The preliminary Alert list discusses 21 species to be on the look-out for, most of which are insects and most of which can be expected to cause important damage to crops and/or nature, or both, if introduced.

Date
2011
Data type
Research report
Theme
Research and monitoring
Report number
C193/11
Geographic location
Aruba
Bonaire
Curacao
Saba
St. Eustatius
St. Maarten

A status report of nature policy development and implementation in the Dutch Caribbean

The National Nature Policy Plan 2001-2005 (NPP-5) and its current status of implementation was assessed as a first step towards a new Nature Policy Plan for the Caribbean Netherlands (Bonaire, Saba, St. Eustatius). The purpose of this exercise is to determine which action points of NPP-5 are still relevant, and to identify key new developments to be aware of when setting goals and strategies for the new Nature Policy Plan for the Caribbean Netherlands. The NPP-5 was the first formal nature policy plan of the Netherlands Antilles. It lists a total of 47 policy goals and projects in the text for the period 2001-2005. Based on these, 61 action points were listed in an Action Matrix for the period 2001-2005. Of these 31 were achieved to a high degree of completion between 2001 and 2010, notwithstanding the serious and chronic lack of both funds and manpower (NEPP-7). Based on this assessment, a total of 40 action points may be brought forward based on the NPP-5. These not only include most “one-time” action points not yet achieved but also several action points that were achieved but which are of an on-going nature.

While much has been achieved in terms of policy development and legal frameworks over the last 10 years, climate change implies that future nature management will be confronted with an increasingly rapid succession of major ecological problems such as coral bleaching, hurricane impacts, and invading species.

Our quick-scan assessment showed that policy development over the last 10 years has suffered significantly from challenges in terms of both capacity and funding, as well as in decision-making in reaching its goals. Controversial topics regarding “rules and regulations”, “cooperation”, and “financial instruments” largely failed to be achieved due to problems in the decision making process, whereas less controversial action points such as “reporting”, drawing up “plans”, doing “research” and “education”, especially suffered from a lack of capacity and funding.

Several main topics are identified that will need attention in the new nature management plan. The new nature policy will have to meet standard and basic policy needs, information and management needs, and also have to accommodate the latest conceptual developments and the pressing realities of global climate change and alien species invasions. Notable is that a large number of new and serious threats have come to the forefront since the NPP-5 was set 10 years ago.

Because the diverse, colourful and unique natural ecosystems of the Caribbean Netherlands also represent the single most important local economic resource on which to build long-term prosperity of the inhabitants of these islands, the nature policy plan needs to be recognized as much more than simply a way to protect nature and avert ecological crisis. It is in fact a key policy tool by which to actively safeguard and create economic well-being and opportunity for these islands.

Date
2011
Data type
Research report
Theme
Governance
Report number
C065/11
Geographic location
Saba

A status report of nature policy development and implementation in the Dutch Caribbean over the last 10 years and recommendations towards the Nature Policy Plan 2012-2017

The National Nature Policy Plan 2001-2005 (NPP-5) and its current status of implementation was assessed as a first step towards a new Nature Policy Plan for the Caribbean Netherlands (Bonaire, Saba, St. Eustatius). The purpose of this exercise is to determine which action points of NPP-5 are still relevant, and to identify key new developments to be aware of when setting goals and strategies for the new Nature Policy Plan for the Caribbean Netherlands. The NPP-5 was the first formal nature policy plan of the Netherlands Antilles. It lists a total of 47 policy goals and projects in the text for the period 2001- 2005. Based on these, 61 action points were listed in an Action Matrix for the period 2001-2005. Of these 31 were achieved to a high degree of completion between 2001 and 2010, notwithstanding the serious and chronic lack of both funds and manpower (NEPP-7). Based on this assessment, a total of 40 action points may be brought forward based on the NPP-5. These not only include most “one-time” action points not yet achieved but also several action points that were achieved but which are of an on-going nature.

While much has been achieved in terms of policy development and legal frameworks over the last 10 years, climate change implies that future nature management will be confronted with an increasingly rapid succession of major ecological problems such as coral bleaching, hurricane impacts, and invading species.

Our quick-scan assessment showed that policy development over the last 10 years has suffered significantly from challenges in terms of both capacity and funding, as well as in decision-making in reaching its goals. Controversial topics regarding “rules and regulations”, “cooperation”, and “financial instruments” largely failed to be achieved due to problems in the decision making process, whereas less controversial action points such as “reporting”, drawing up “plans”, doing “research” and “education”, especially suffered from a lack of capacity and funding.

Several main topics are identified that will need attention in the new nature management plan. The new nature policy will have to meet standard and basic policy needs, information and management needs, and also have to accommodate the latest conceptual developments and the pressing realities of global climate change and alien species invasions. Notable is that a large number of new and serious threats have come to the forefront since the NPP-5 was set 10 years ago.

Because the diverse, colourful and unique natural ecosystems of the Caribbean Netherlands also represent the single most important local economic resource on which to build long-term prosperity of the inhabitants of these islands, the nature policy plan needs to be recognized as much more than simply a way to protect nature and avert ecological crisis. It is in fact a key policy tool by which to actively safeguard and create economic well-being and opportunity for these islands. 

Date
2011
Data type
Research report
Theme
Governance
Report number
C065/11
Geographic location
Bonaire
Saba
St. Eustatius