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The University of the West Indies Organization of

American States

PROFESSIONAL DEVELOPMENT PROGRAMME:

COASTAL INFRASTRUCTURE DESIGN, CONSTRUCTION AND MAINTENANCE

A COURSE IN

COASTAL ZONE/ISLAND SYSTEMS MANAGEMENT

CHAPTER 7

MARINE BIOLOGICAL ISSUES

By JUDITH GOBIN, PhD Part-time Lecturer, Faculty of Engineering

University of the West Indies St. Augustine Campus Trinidad, West Indies

Organized by Department of Civil Engineering, The University of the West Indies, in conjunction with Old Dominion University, Norfolk, VA, USA and Coastal Engineering Research Centre, US Army, Corps of Engineers, Vicksburg, MS , USA.

Antigua, West Indies, June 18-22, 2001

Marine Biological Issues By Judith Gobin Coastal Zone/Island Systems Management CDCM Professional Development Training, 2001

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This lecture is adapted from the paper “The Lesser Antilles, Trinidad and Tobago” by John B.R. Agard and Judith F. Gobin in Seas at the Millennium: An Environmental Evaluation (Ed. C. Sheppard) 2000 Elsevier Science Ltd.

1.0 INTRODUCTION

All the islands of the Lesser Antilles have coasts that border on both the tropical western

Atlantic and the Caribbean Sea. Major sills in the passages between these islands are the

controllers of water flow into the Caribbean Sea from the Atlantic Ocean. Horizontal

motion below the average sill depth of the Antillean Arc (1200m) is almost stagnant.

These islands are probably the most important physiographic features of the Caribbean

Sea as they act as the gatekeepers to the integrity of the Caribbean marine environment.

The coastal marine environments around the islands are generally oases of high

production associated with shallow waters, coral reefs, mangrove swamps, estuaries and

coastal lagoons surrounded by deep oligotrophic seas.

The oceanography of the southern Lesser Antilles is strongly influenced by the outflow of

two of the world’s largest river systems, the Amazon and the Orinoco. Superimposed on

this regime are the periodic passage of large eddies of Amazon water from the Guyana

Current. The marine production of offshore waters is generally low due to the relatively

stable thermocline, which in the absence of significant upwelling prevents the mixing of

nutrient rich deep waters with surface waters. The main seasonal variation of the islands

is due to rainfall. Hurricanes are another periodic event that occasionally has significant

impacts on the marine biota of these islands.

Penaeid shrimp dependent on estuarine conditions and muddy bottoms are the most

valuable fishery resource harvested on the continental shelf between Trinidad and

Venezuela. Pelagic fishes offshore (e.g. flyingfish, kingfish, dolphinfish, tuna, swordfish,

sharks) and inshore (e.g. kingfish, jacks, herrings and anchovies) are the main commercial

fisheries resource exploited among the islands in the area of mixed water stretching from

the north coast of Trinidad to St Vincent. In the clear blue oligotrophic waters from St


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Lucia to the Virgin Islands the only significant fisheries are for lobsters and conchs

inshore, and for tuna offshore. Only Trinidad and Tobago and the French islands of

Martinique and Guadeloupe show any noticeable increase in fish catches from 1990-95.

Large commercial fishing vessels from several nations not indigenous to the sub-region

frequently exploit the limited fish stocks within the Exclusive Economic Zone of these

islands. In many cases, these vessels operate without the knowledge and consent of island

governments. All of the islands have fisheries legislation but a shortage of trained

personnel and the high cost of effective fisheries patrols in offshore as well as inshore

waters and marine parks hinder their effective enforcement.

In these islands human impacts on the marine environment are significant because

population density is high ranging from 83 km-2 in Anguilla to 614 km-2 in Barbados.

Ongoing deforestation is a serious problem affecting the coastal zone in Trinidad and

Tobago, Guadeloupe, Martinique, St Lucia and the British Virgin Islands. Artisanal

fishing methods such as trawling for shrimp, cutting mangrove roots to harvest oysters,

over harvesting of edible sea urchins, lobsters and conch, also damage marine habitats.

Beach sand mining is the major human induced cause of coastal erosion in the Eastern

Caribbean. Marine pollution from inadequately treated sewage effluents is a problem on

every island because of the lack of adequately maintained centralised sewage treatment

facilities.

The annual number of tourist arrivals in individual islands is substantially greater than

their resident population in 12 out of 14 instances excluding only Dominica and Trinidad.

Airport and marina construction to provide facilities for tourists have resulted in the

filling in of coastal mangroves and increasing sedimentation in coral reef and seagrass

areas. The development of heavy industry in the coastal zones of the various territories is

very limited except for the island of Trinidad. Dense petrochemical related shipping


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traffic passing through narrow straits around Trinidad and Tobago make this area a high-

risk zone for marine pollution from shipping accidents.

The Lesser Antillean countries are signatories to several important international

conventions and programs, which are geared to protect the marine and coastal

environment. However, the record of implementing the provisions of these conventions is

very poor. Further, there are few significant ongoing marine investigations in the sub-

region except for those undertaken through the Caribbean Coastal Marine Productivity

(CARICOMP) network of Marine Laboratories, Parks and Reserves. The islands will

have to significantly increase their environmental protection efforts if they are to stem the

tide of pollution and natural resource depletion.

2.0 THE DEFINED REGION

This review covers the Lesser Antillean arc of islands in the Eastern Caribbean, as well as

the islands of Trinidad and Tobago, which are geologically parts of the South American

continent. The sub-region includes the following countries: Anguilla, Antigua and

Barbuda, Barbados, British Virgin Islands, Dominica, Grenada, Guadeloupe, Martinique,

Montserrat, Netherlands Antilles (Saba and St. Eustatius), St. Kitts (St. Christopher) -

Nevis, St. Vincent and the Grenadines, St. Lucia, Trinidad and Tobago, U.S.Virgin

Islands (Fig. 1). All the islands of the archipelago have coasts that border on both the

tropical southwest Atlantic and the Caribbean Sea. Major sills in the passages between

these islands are the controllers of water flow into the Caribbean Sea from the Atlantic

Ocean (Fig. 1). Horizontal motion below the average sill depth of the Antillean Arc

(1200m) is almost stagnant. These islands are probably the most important physiographic

features of the Caribbean Sea as they act as the gatekeepers to the integrity of the

Caribbean marine environment from the Atlantic Ocean. The water forcing its way in the


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upper layer of the sea, through the narrow channels between the islands creates jet

currents as well as large turbulent wakes and eddies. These currents may concentrate

marine organisms as well as nutrients and pollutants in the wake of islands. The coastal

marine environments around the islands are generally oases of high production associated

with shallow waters, coral reefs, mangrove swamps, estuaries and coastal lagoons

surrounded by deep oligotrophic seas. The well being of these small islands is therefore

intimately associated with the protection of their coastal ecosystems. The area seems

amenable to the large marine ecosystem (LME) approach to managing marine resources.

However, since this LME includes the territorial waters of 15 countries, the effectiveness

of this management tool is dependent on the co-operation of all the bordering countries.

3.0 SEASONALITY,CURRENTS, NATURAL ENVIRONMENTAL VARIABLES

Ocean surface temperatures are about 27 oC with seasonal fluctuations of no more than 3 oC and a decrease of 10-15 oC within the upper 200m, beyond which there is little change.

The main seasonal variation of the islands is due to rainfall. The seasons are caused by

the annual displacement of the Inter-tropical Conversion Zone (ICTZ) northward during

April to September and it’s return southward during January to March. The climate year

is divided into a dry season lasting from about January to May and a wet season from

June to December. There are differences in precipitation between the islands with rainfall

being highest among the central islands of the Antillean arc from Anguilla to Dominica.

The effect of local rainfall on the marine biota is generally insignificant in comparison

with the dominant hydrographic regime.

The oceanography of the southern Lesser Antilles is strongly influenced by the outflow of

two of the world’s largest river systems, the Amazon and the Orinoco. Together they

account for about 20 % of fresh water discharges into the world’s oceans. During


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February to May, the Guyana Current advects water of high primary productivity and

sediment concentration from the Amazon River along the edge of the continental shelf of

northern South America. It then curves left to join the North Equatorial Current as it

enters the Caribbean Sea in a broad 150-200 km stream mainly between Tobago and

Barbados (Fig. 1). During this period, the discharge of the Orinoco is low and among the

islands, only Trinidad is under its influence.

During June to January, the North Brazil Current retroflects or veers offshore into the

North Equatorial Counter Current taking about 60% of the annual discharge of Amazon

water eastwards toward Africa. Offshore in the Atlantic, this water mixes with the North

Equatorial Counter Current before the lens of low salinity water enters the south-eastern

Caribbean about six months to a year later (Muller-Karger, McClain and Richardson,

1988). These events seem to cause diminished flow between the islands of the eastern

Caribbean by diverting a major source of water for the Guyana Current. The weakening

of the Guyana Current permits the north-westward dispersal of Orinoco water from the

Gulf of Paria towards the Antilles due to eastern Caribbean Ekman forcing (Muller-

Karger and Varela, 1990). During the peak of the wet season from July to November, the

discharge of the Orinoco may completely engulf Trinidad, Tobago, Grenada and St.

Vincent (Plate 1). The gradient of surface salinity may then range from 20 ppt near the

Mouth of the Gulf of Paria between Trinidad and Venezuela, to 36 ppt in the oligotropic

waters of the Antilles Current around the Virgin Islands.

The retroflection of the North Brazil Current in the Atlantic also causes pieces of that

current to break off and form eddies of up to 400 km diameter with swirl speeds of 17-84

cm/sec (Richardson et. al., 1994). Some eddies loop from the surface down to depths of

900 to 1200 m as they translate north-westward at a speed of 4-16 cm/sec towards the

Lesser Antilles. The relative shallowness (350-1000m below sea level) and narrowness

(220 km) of the gap between Barbados and Tobago may cause the Eddies to disintegrate


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as they try to pass between the islands into the Caribbean Sea (Fig. 1). They are

occasionally large enough to engulf the island of Barbados with consequent sudden

changes in salinity and phytoplankton species composition (Stansfield et. al., 1995).

Thus, the gradient of oceanographic conditions around the islands constitutes the major

overall environmental determinant of habitat boundaries. These include:

(a) Estuarine conditions and dark green or brown turbid waters (seen as red and yellow

in Plate 1) around Trinidad and Tobago due to the influence of the Orinoco and

Amazon Rivers. During the dry season in the early part of the year the system is

affected by the periodic passage of large eddies in the Guyana Current, while during

the later part of the year the major hydrographic influence is from the flood waters of

the Orinoco River

(b) Intermediate aquamarine waters (seen as blue-green in Plate 1) from Grenada to St.

Vincent, which during the first half of the year are formed by the mixing of water

from the oligotrophic Atlantic North Equatorial Current with sediment and plankton

laden Amazon River water from the previous season. Later in the year the area of

intermediate water is formed by the mixing of the North Equatorial Current with the

edge of the Orinoco River plume.

(c) Oligotrophic clear bluish waters (seen as dark blue in Plate 1) from the Atlantic

North Equatorial Current and Antilles Current flowing into the Caribbean Sea above

sill depth between the islands stretching from St Lucia to the Virgin Islands.

Mangrove communities occur throughout the sub-region but attain their most extensive

development in the estuarine conditions at the Trinidad end of the Antillean arc. The

more southerly coral reefs at Trinidad have a reduced coral diversity dominated by

species living at the limit of their tolerance to low salinity and suspended sediments.

Conversely, coral reefs are more diverse and seagrass beds more extensive in the

oligotrophic waters found from the Virgin Islands to St. Lucia.


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Hurricanes and tropical storms may also have an impact on the marine biota of these

islands. They form in the area between 5-10o off the equator over the tropical Atlantic

Ocean where the surface temperature is in excess of 26.7 oC. They derive their kinetic

energy from latent heat of condensation and serve to transport this accumulated energy

and precipitable water mass poleward. The Coriolis force is the cause of the rotation and

they may typically extend from 100 km to as much as 1500 km in diameter at maturity.

Their normal track takes them westward across the Atlantic between June and November

where they typically pass on the Atlantic side of the Leeward Islands with the highest

frequency occurring in September (Fig. 1). The probability of storms making landfall

decreases sharply towards the Trinidad and Tobago end of the Lesser Antilles.

Coral reefs seem able to survive the other mainly temporary physical effects of average

storms such as tidal surge; increased inundation with consequent reduced salinities and

increased suspended solids and nutrients from land runoff. However, since 1960 their

intensity has increased giving rise to some of the most intense storms ever experienced in

the region, e.g. David, Allen, Gloria, Gilbert, Hugo, Andrew and Georges. The most

powerful hurricanes can affect coral reefs through the physical removal of live corals.

Algae and pioneer coral genera such as Agaracia, Porites, Favia and Millepora may be

the first to colonize the exposed substrate or broken coral fragments. Hurricanes may also

favour the spread of branching genera of corals such as Acropora. The breaking off,

scattering and re-growth of the numerous asexual recruits favours the spread of this genus

and others with a similar growth form (Fong and Lirman, 1995). Destruction of these

overhanging branching colonies also benefits slower-growing massive corals by allowing

them more light for growth (Rogers et. al., 1982). Other known ecological effects are the

reduction of shelter for fish and other organisms, as well as the provision of new surfaces

for colonisation by algae and invertebrates. In Martinique very strong hurricanes have

also flattened but not uprooted the mangrove trees of entire swamps. Observation

suggests that the increased surface area for settlement provided by the mangrove branches


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dipping into the water, favoured encrusting species such as oysters. Of greater concern in

the islands is storm surge, which can erode up to10 metres of beach within an hour.

Hurricanes may also bring another beneficial effect through the upwelling of nutrient rich

water along or near the track temporarily improving fisheries production.

4.0 THE MAJOR SHALLOW WATER MARINE AND COASTAL HABITATS

Except for Trinidad and Tobago the marine production of the Lesser Antilles is

constrained by the lack of a shallow continental shelf and the relatively stable

thermocline. In the absence of significant upwelling, these factors prevent the mixing of

nutrient rich deep waters with surface waters. Coral reefs, mangrove swamps and seagrass

beds have all solved the problem of obtaining nutrients under these conditions and are the

three most important coastal habitats in the sub-region. There are many direct links

between the extent and health of these habitats and the productivity of the inshore

fisheries, which support human populations. The majority of bottom-dwelling fish species

in the shallow nearshore waters of the Eastern Caribbean (more than 300 species, of

which an estimated 180 species are landed for human consumption) are associated with

coral reefs as adults (Towle and Towle, 1991). Many of these reef fishes as well as conch

and lobsters, utilise mangrove swamps and/or seagrass beds as nursery habitats in their

juvenile stages. Mangroves may act as an exporter of nutrients or traps for terrigenous

materials and as such their removal adversely affects coastal water quality, frequently

with deleterious consequences for adjacent coral reefs. Coral reefs and sea grass beds also

protect coastal areas from erosion. Trinidad being on the continental shelf in the estuary

of the Orinoco River is an exception to overall prevailing low nutrient conditions. This

has given rise to exceptionally high primary productivity in the shallow Gulf of Paria. The

muddy bottom of the area also has a diverse and highly productive benthic fauna, which

supports the enhanced fisheries production of this area compared to the other islands. The


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Gulf of Paria coast of Trinidad also has some hydrocarbon adapted invertebrate fauna

associated with natural oil seepage (Agard et al., 1993)

The small islands of the Lesser Antilles have relatively extensive coastlines in

comparison to their land area and almost every coastline has mangroves (Table 1). The

total area of mangroves in the Lesser Antilles is about 20,636 hectares comprising seven

species. The Red mangrove Rhizophora mangle is most common while R. harrisonii and

R. racemosa are apparently restricted to Trinidad. The Black mangrove Avicennia

germinans is widespread, whereas A. schauerina is present on several islands but

nowhere common. White mangrove Laguncularia racemosa is present on most islands

but rarely forms large stands and Button mangrove Conocarpus erectus is a common

component of wetland margins and littoral woodlands (Bacon, 1993).

The largest mangrove swamps are found where there are extensive river systems (e.g.

Trinidad) or islands with low-relief coastal plains with substantial freshwater inflow (e.g.

Guadeloupe). In this sub-region the endangered West Indian manatee (Tricheus manatus)

which once ranged throughout the Lesser Antilles is now solely represented by about a

dozen adults in the Nariva Swamp on the East Coast of Trinidad. In the smaller islands of

the Eastern Caribbean spatial coverage by mangroves may be restricted (Table 1) and the

trees often show poor development in the form of low coastal scrub (e.g. Barbados,

Dominica, Montserrat, St. Vincent and the Grenadines. The main factors responsible for

this are limited freshwater runoff, hypersaline conditions, wave exposure and seasonal

hurricanes. The biomass of Caribbean mangroves including sites at Barbados and

Trinidad, ranges from 1 to 19 kg.m2 which appears to fall within the lower part of the

global spectrum of biomass data (CARICOMP Program, 1997).

Almost every island in the sub-region has coral reefs (Table 1). Reef development is

greatest on islands with low rainfall and little sedimentary runoff such as Antigua and


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Barbuda, St. Vincent and the Grenadines. Lesser Antillean reefs seem quite uniform with

about 37 species of hermatypic scleractinian corals. Trinidad is an exception as it has a

reduced coral biodiversity of about 17 species due to the high sediment load from the

Orinoco River. Noticeably absent from Trinidad are common Caribbean coral genera

such as Madracis, Isophyllia and Mycetophyllia. One of the major species responsible for

maintaining the ecology of Caribbean coral reefs is the sea urchin Diadema antillarium.

This species is herbivorous and a bioeroder. In 1983 the importance of this keystone

species became apparent when D. antillarum were reduced to about 1% of their normal

abundance. The postulated cause was the spread of a pathogen from Panama to the Lesser

Antilles and the rest of the Caribbean. In the aftermath of the epidemic, algal overgrowth

of corals caused major changes in the community ecology of coral reefs (Lessios, 1988).

Seagrass beds of Thalassia testudinum or turtle grass occur throughout the islands. Other

species such as Halodule wrightii and Syringodium filaforme are frequently interspersed

but nowhere common. The highest measured seagrass biomass in the sub-region is at

Barbados (2900-3800 g/m2) while the lowest is in Tobago (200-500 g/m2) (CARICOMP,

1997a). Seagrass beds stabilise bottom sediments, retard coastal erosion and provide

grazing for the green turtle (Chelonia mydas), manatees (Tricheus manatus) and

parrotfish (Scaridae). Snappers (Lutjanidae), grunts (Scaridae), queen conch (Strombus

gigas) and the edible sea urchin (Tripneustes esculentus) all forage in seagrass meadows.

Other common benthically rooted algae are Caulerpa, Halimeda, Penicillus,

Rhipocephalus and Udotea.

5.0 OFFSHORE SYSTEMS

The offshore hydrography of the region is dominated by a subsurface high saline water

mass between depths of 100 to 200 metres with a salinity maximum of 36.8 ppt and


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temperatures from 22 to 23 oC (Kumar et al., 1991). This is referred to as subtropical

underwater. Below this can be found Antartic intermediate water at a depth of 700-800 m,

a salinity maximum of 35.0 ppt and temperature of about 6-7 oC. This water mass enters

the Caribbean Sea through the Grenada passage after being carried by the Guyana current.

A major offshore feature of the region is the intrusion of a lens of low salinity water

(<33.5 ppt) from the Amazon discharge, with a vertical extent of up to 50 m depth

between Tobago and Barbados. During the wet season the surface waters of the south-

eastern Caribbean are influenced by the freshwater discharge of the Orinoco River. There

is no significant upwelling in the region although strong localised upwelling occurs

seasonally along the north coast of Trinidad.

Water column primary production along the island arc is low ranging from 102 –2026

(av. 391) mg C. m-3 .d-1 with highest values associated with the intrusion of Amazon

water (Bhattathiri et al., 1991). Typically, diatoms of the genera Navicula and

Coscinodiscus dominate phytoplankton in the estuarine conditions between Trinidad and

Tobago. In the intermediate conditions extending from Tobago to Barbados and St

Vincent a mixed bloom of diatoms comprising Chaetoceros sp., Thalassiothrix sp.,

Rhizosolenia faroensis and Skelotenema sp. can usually be found. In the oligotrophic

waters from St. Lucia to the Virgin Islands blue-green algae of the genus Trichodesmium

dominate (Agard et al., 1996).

Due to the generally nutrient impoverished nature of offshore areas in the Caribbean Sea,

shelf area and river influences are the major influences on fisheries production in the

Eastern Caribbean. Penaeid shrimp which are dependent on estuarine conditions and

muddy bottoms are the most valuable fishery resource harvested from the dark green or

turbid brown water around Trinidad (Table 2). Pelagic fishes offshore (e.g. flyingfish,

kingfish, dolphinfish, tuna, swordfish, sharks) and inshore (e.g. kingfish, jacks, herrings

and anchovies) are the main commercial fisheries resource exploited among the islands in


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the area of mixed water stretching from Trinidad and Tobago to St Vincent. In the clear

blue oligotrophic waters from St Lucia to the Virgin Islands the only significant fisheries

are for lobsters, conchs and tuna offshore. Occasionally, some coral reef fishes are

harvested for the marine aquarium trade. Sailfish and Blue marlins caught by charter

boats are increasing in importance. Total fish catches landed for all the Lesser Antilles are

relatively small at about 39,000 metric tons and show no indication of significant increase

from 1990-95 (Table 2). Expansion of fisheries exploitation in the region has traditionally

been hindered by over-fishing of near-coastal waters by subsistence and other small scale

fishers, reliance on small open wooden fishing boats and inadequate cold storage

facilities. Another problem, which is currently being addressed, is increasing co-operation

between neighbouring countries to facilitate stock assessment of shared stocks.

Meanwhile large commercial fishing vessels from several nations not indigenous to the

sub-region are exploiting the limited fish stocks in the EEZ’s of these islands. In many

cases, these vessels operate without the approval of island governments. All of the islands

have fisheries legislation in place but a shortage of trained personnel and the high cost of

effective fisheries patrols in offshore as well as inshore waters and marine parks hinder

their effective enforcement.

6.0 POPULATIONS AFFECTING THE AREA

Human beings adversely affect the marine environment through waste disposal and

natural resource depletion. The magnitudes of these impacts are influenced by

demographic characteristics such as population size, growth rate, density, distribution,

financial income and access to sanitary facilities. The islands of the Eastern Caribbean are

very small with surface areas of the major islands ranging from 96 to 5130 km-2. In such

small islands human impacts on the marine environment are significant because

population density is high ranging from 83 km-2 in Anguilla to 614 km-2 in Barbados (see

Table 3).


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There are large differences in the rates of population change in these islands ranging from

–0.5 in St. Kitts/Nevis to 3.4 in the British Virgin Islands (the former figure being largely

due to emigration and the latter figure to immigration). It is noticeable that most of the

islands (9 out of 14) have growth rates of less than 1.0 % per year (Table 3). The average

annual rate of population growth for the Lesser Antilles during the first half of the 1990’s

was about 1.0 % as compared to 1.7 % during the 1980’s and higher values in the

previous four decades. This suggests that the islands are approaching the mature stage of

the demographic cycle with the population growth rate declining.

The total population of the Lesser Antilles in 1995 was estimated to be about 3 million

persons (Table 3). Despite the general decrease in population growth rate, if present

trends continue the total population size will grow by about 76,000 persons between 1995

and the year 2000. The populations of the islands are concentrated in the coastal zone and

on average about 15 % live in the capital cities. An exception is Barbados where about 46

% of the population reside in the capital Bridgetown.

There is widespread concern that the disproportionate reliance of the island economies on

the resources of the coastal environment makes them sensitive to the impacts of

expanding human population. Even so, the history of marine investigations into the

conditions of the area is short. Marine studies in the sub-region other than for fisheries

purposes could be described as spasmodic and largely dependent on the transit of research

vessels from metropolitan countries. These studies typically lasted no more than a few

days. Some investigations were however more deliberate and for example Cruise P-6907

by the R/V JOHN ELLIOTT PILLSBURY from RSMAS at the University of Miami took

bottom trawls or dredges at more than 100 stations in the Lesser Antilles during 1969.

From the late 1960’s a few marine science and natural resource management oriented


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organisations developed in the Lesser Antilles. The largest of these is the Institute of

Marine Affairs (IMA) located in Trinidad. These organisations are largely devoted to

collecting baseline information relative to their individual islands and only a few regional

studies have been done to-date. A notable exception is the ongoing fisheries assessment

program conducted through the Organisation of Eastern Caribbean States and Canadian

International Development Authority (OECS/CIDA). Similarly, the Caribbean

Oceanographic Resources Exploration (CORE) which involved scientists from the

Caribbean and India was able to collect physical and biological oceanographic baseline

data for the sub-region. The most important ongoing initiative is the Caribbean Coastal

Marine Productivity (CARICOMP) research and monitoring network of Marine

Laboratories, Parks and Reserves. The network was established in 1990 and currently

involves 25 sites in 16 countries in the Wider Caribbean. Three of these sites are in the

Lesser Antilles at Saba, Barbados and Tobago. The network conducts a standardised,

synoptic set of measurements of the structure, productivity, and associated physical

parameters of relatively undisturbed coral reefs, seagrasses, and mangroves. The principal

goals of the program are to determine the dominant influences on coastal productivity and

to discriminate human disturbance from long-term natural variation in coastal systems

over the full regional range of their distribution (CARICOMP, 1997b).

7.0 RURAL FACTORS

Agriculture in the eastern Caribbean is organised on three basic production systems:

large-scale plantation agriculture; small-scale sedentary farm agriculture; and migratory

or shifting agriculture (Gumbs, 1981). The dominant large-scale plantation agriculture

generally produces export crops such as sugar, bananas and cocoa. The production of

these crops is based on a mechanised monoculture system on flat land, which requires

high inputs of fertilisers and pesticides. Total fertiliser consumption in the sub-region at

46.6 thousand metric tons is high and increasing in most countries (Table 4). More than


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half of this amount consists of nitrogenous and phosphate fertilisers, which may cause

algal blooms when, washed into the marine environment. Runoff of soils and chemicals

occurs during the rainy season when the land is laid bare. Degradation of the soil occurs

over time and chemicals may find their way via waterways or directly into sensitive

marine habitats. In one recorded incident, during 1978 mercury and DDT used as a seed

dressing at an agricultural facility in Chaguaramas Trinidad washed down into the sea via

a river causing a massive fish kill.

Small privately owned farms, the second most important of the agricultural systems in the

sub-region, produce export crops in addition to food crops for the domestic market.

Farms are frequently located on marginal lands and farming practices are often poor due

to financial constraints and lack of access to modern technology. Poor knowledge of the

ecological effects frequently results in the indiscriminate application of chemicals with

consequent runoff to aquatic systems.

The most significant agricultural effect on the environment comes from slash-and-burn

farming. In this method forest is clear felled and the vegetation burned in the dry season,

in order to plant crops in time for the approaching rainy season. The farmer makes

minimal inputs to maintain this subsistence level of farming and there is little or no soil

conservation. This form of shifting agriculture is usually practised on highly erodable

soils on steep mountain slopes. It is the major cause of deforestation in the region. The

problem is most acute in Trinidad and Tobago with deforestation taking place at an

average rate of 3,000 hectares per annum (Table 5). Deforestation is also a serious

problem in Guadeloupe, Martinique, the British Virgin Islands, St. Kitts and Nevis. In the

other islands forest cover appears to be stable but in some cases such as Barbados and the

U.S. Virgin Islands all the old growth forests have already been removed. Since Trinidad

is in an estuarine area with naturally high, suspended sediments, turbidity in the coastal

zone due to soil erosion from deforestation has less effect on coastal marine species,


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which are already tolerant to some degree. On the other hand, all of the other islands have

numerous coral reefs, which may be easily smothered by eroded sediments from

deforestation.

Artisanal fishing methods can also damage marine habitats. For example, trawling for

shrimp by scraping up the seabed in Trinidad has destroyed nursery grounds and the

habitat of demersal species with a near collapse of inshore fisheries. In addition, the by-

catch is discarded along with the juveniles of many non-target species. In Trinidad,

oysters are harvested by cutting off the entire prop-roots of red mangrove on which they

have settled (rather than scraping off the oysters). This practice systematically reduces the

amount of suitable substrate available for oysters to settle with a consequent decline in

the fishery. Over harvesting of lobsters and conch in several islands has led to a switch

from relying on traps to employing dive teams whose efforts to remove animals from

their hiding places often result in damage to reefs. In St. Lucia and elsewhere, Sea Moss

(Gracilaria spp.) is harvested by pulling the entire plant from the substrate, preventing

regeneration. This practice has led to a decline in wild stocks. Other threats to coral reef

systems include collection of live coral specimens for sale as souvenirs.

8.0 COASTAL EROSION AND LANDFILL

Beach sand mining is the major human induced cause of coastal erosion in the eastern

Caribbean. Throughout the sub-region, beach sand has been traditionally regarded as a

free natural resource available for the taking by anyone. This attitude has had disastrous

consequences for the sub-region, which governments have only been recently trying to

address.


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Beach sand mining (1990 est. 96,000 tons) in St. Vincent and the Grenadines has been the

cause of severe beach erosion, flooding of coastal areas, loss of dunes and other habitats.

In order to address the situation, the government decided as of January 1st, 1995 to import

sand from Guyana for all government projects and to implement controls on beach sand

mining. This action was widely expected to cause an increase in the cost of construction

and so there was a massive stockpiling of sand. In a two month period the volume of sand

mined from the beaches was 2.5 times the annual volume (Porter, 1997). This caused

serious erosion, which was accentuated by tropical storm Iris in August 1995. Similarly in

Tobago, beach sand mining has caused severe erosion and although the practice has been

brought under a licensing system, few beaches have shown signs of recovery. In Grenada

the story is similar, with beach sand mining continuing at the rate of up to 65,000 cubic

yards per year. Another common practice is offshore dredging to re-establish hotel

beaches removed by hurricanes. This has occurred in Anguilla, Barbados, St Kits/Nevis

and St. Lucia. Dredge and filling of mangrove areas to construct Marinas and Resort

developments is also now a common feature of the region.

9.0 EFFECTS FROM URBAN AND INDUSTRIAL ACTIVITIES

9.1 Artisanal and non industrial uses of the coast

In the Lesser Antilles, humpback whales (Megaptera novaeangliae) migrate annually to

calving grounds in the Grenadines and also between the islands of Antigua and Anguilla.

This has been the basis for the operation of two shore-based artisanal fisheries for whales.

The island of Bequia in the Grenadines has a whaling industry dating back to1875 and is

allowed an aboriginal whaling quota of three humpback whales per year by the

International Whaling Commission (Ward, 1987). Between 1950 and 1984, it has been

estimated that between 52-70 Humpback whales were killed by the Bequia fishery, about

70% of them females. The harvest is strictly for local consumption. Occasionally


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Dolphins, Sperm Whales and Killer Whales are also taken. Another fishery for pilot

whales (Globicephala macrorhyncus) is based in St. Vincent, with a few boats operating

out of St. Lucia. Both whale fisheries are in rapid decline and soon expected to be of little

more than historical interest.

Hawksbill turtles (Chelonia mydas) are heavily exploited in the Grenadines and small

turtles are captured with spearguns to be stuffed and sold as tourist curios. Stony corals

and black corals are also sold to tourist as curios.

The white-spined sea urchin (Tripneustes ventricosus) is harvested in the Caribbean for

its edible roe. The demand for the delicacy has led to severe over-harvesting especially in

St Lucia, Barbados, the Tobago Cays and the French islands. In 1990 the Government of

St. Lucia introduced a co-management arrangement of the fishery with community

groups. These groups are licensed for the harvesting season, in return for their observing

minimum size limits and restrictions on harvest location (Smith and Berkes, 1991).

In St. Lucia the Mankote mangrove has been traditionally used as a source of wood for

charcoal production. Over-harvesting and the declaration of the island mangroves as

Marine Reserve Areas have led to the development of a fuel-wood reforestation project

using Leucaena sp. as an alternative.

In Tobago, local boatmen use glass-bottomed boats to ferry tourists out to view the

popular Buccoo Reef. Visitors are encouraged to disembark into the water on the reef and

walk, frequently trampling corals under their sandaled feet. Current practice by Park

authorities is to discourage the activity or confine it to already degraded areas.


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9.2 Industrial uses of the coast

In the Lesser Antilles there are only two large scale industrial uses of the coast where

significant ownership and profits are held extra-regionally viz.- tourism in all islands and

oil and gas exploitation together with petrochemical production in Trinidad. The tourism

resource mainly comprises pristine natural assets such as beaches and coral reefs or island

culture as well as physical plant such as hotels and marinas. Most of the large hotels and

resorts are owned by international hotel chains or groups of foreign investors. Although

tourism is the major source of income for the sub-region, it often creates problems where

it exceeds the carrying capacity of the coastal zone to provide facilities for tourists. Total

tourism receipts in the sub-region of about 3.5 billion US$ during 1995 represent a 29.6%

increase compared to 1991 (Table 6). Tourist arrivals of about 3.314 million persons to

the region in 1995 were greater than the entire population (1995 est. 3.045 million, Table

6) of the Eastern Caribbean. The annual number of tourist arrivals in individual islands is

substantially greater than their resident population in 12 out of 14 instances excluding

only Dominica and Trinidad (cf. Tables 3 and 6). Further, tourist arrivals to the sub-

region are increasing at the rate of about 5.6% or 145,800 persons per annum. One

undesirable trend is that in Trinidad and Tobago although tourist arrivals have been

increasing, tourism receipts have dropped. This it is suggested is due mainly to an

increase in the influx of cruise ship passengers whose all-inclusive accommodations

provide little return to the country.

In order to supply the needs of tourists, one of the unfortunate side effects of the

extraordinary financial success of this industry is pollution and degradation of the coastal

environment. Airport and marina construction have resulted in the filling in of coastal

mangroves and increased sedimentation in coral reef and seagrass areas. Rapid

development within the hotel construction industry has been responsible for increased

beach sand mining to supply construction material and for resorts being built too close to

the water. Coral reef damage is also a growing problem because of boats running aground


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or anchoring on them and visitors trampling on them or breaking off pieces for souvenirs.

Spearfishing associated with the lucrative dive tourism industry is also another cause of

depletion of reef communities. Hotel demands for high valued commodities such as

lobsters and conch are the cause of them being over-harvested. Marine pollution from

inadequately treated sewage effluents is a problem on every island because of the lack of

adequate centralised sewage treatment facilities. This has led to the proliferation of poorly

designed, ill-maintained package sewage treatment plants associated with individual

resorts. There are no consistent regulations across the sub-region requiring yachts to have

holding tanks for their sewage wastes and to use shore based waste collection facilities.

This has allowed yachts to empty their sewage wastes directly into the coastal marine

environment solely at their discretion. Fuel and oil waste spillage from ship refuelling

activities is also a widespread problem. Associated with the increase in yacht traffic are

the construction of numerous marinas and boat maintenance facilities in the islands. A

problem of particular concern at these facilities is that throughout the region boats are

being painted with antifouling paints containing extremely toxic organo-tin compounds,

which have been banned for this use in North America and Europe.

The development of heavy industry in the coastal zones of the various territories is very

limited except for the island of Trinidad. The basis of the enormous industrial

development of the island is the exploitation of oil (1996 est. offshore production

36,300,380 Barrels) and natural gas (1996 est. offshore production 804.1 MMcfgd)

mainly by multinational energy companies. Using natural gas from 17 offshore fields as a

feedstock, several energy intensive and world scale petrochemical plants have been

established along the Gulf of Paria coast. These include several iron and steel, iron

carbide, ammonia, methanol, urea, and liquefied natural gas plants among others. The

scale of production is such that at full activation of the installed capacity, Trinidad and

Tobago will be the world’s largest exporter of ammonia (3.455 million tons/year) and

methanol (2,046 million tons/year) by the year 2000. Over a period of 14 years, several


7-21

fish kills in the area have been traced back to industrial effluents especially ammonia

(Heileman and Siung-Chang, 1990) and the risk of such incidents is likely to increase.

Another impact of large-scale industrial development is that the scarcity of unoccupied

flat coastal land for expansion puts pressure on mangrove areas as in Trinidad. An

alternative approach to expansion has also resulted in the smothering of seagrass beds due

to construction of an artificial island offshore.

9.3 Shipping and offshore accidents and impacts

The exploitation of oil is also the source of widespread pollution in the south of the island

of Trinidad. From 1993-95 the mean number of reported oil spills to the marine

environment was 215 per annum resulting in the net annual loss of about 5,000 barrels of

oil on average (unpublished data, Ministry of Energy, Trinidad and Tobago). To this must

be added 100,000 barrels of oil per annum due to effluents, which find there way into the

marine environment via rivers. A further 15,000 barrels of oil enter the marine

environment in produced water from marine installations offshore. Together these inputs

suggest pollution inputs to the marine environment of about 120,000 barrels of oil per

annum. These inputs dwarf the rate of natural oil seepage and oil pollution of marine

sediments extends along the entire western coast of Trinidad but is greatest near oil

refineries (Agard et al. 1988). This pollution has resulted in the massive depletion of soft

bottom benthic communities up to several kilometres away from the sources (Agard et al,

1993).

In the sub-region oil bearing supertankers or cargo ships passing through certain high-risk

zones for shipping accidents, increase the risk of marine pollution in the area. Most at risk

are the more than 1000 large vessels per annum passing between Trinidad and Tobago or

through the narrow entrances to the Gulf of Paria. These vessels transport oil, gas and


7-22

chemicals to industrial estates on the West Coast of Trinidad In fact one of the largest oil

spills ever recorded from a tanker collision occurred on July 19, 1979 just 30km north-

east of Tobago. The collision of two fully laden supertankers the Atlantic Empress and

the Aegean Captain resulted in oil spillage estimated at 90,000 tons. The resulting oil

slick driven by strong winds fortunately moved away from land into the Caribbean Sea.

Another high-risk zone for shipping accidents is the narrow Anegada Passage between the

Virgin Islands because it lies on a major shipping lane to the eastern seaboard of the

United States. This shipping lane passes along the Antillean island arc and is the source

of tar balls occasionally found along windward exposed beaches of the island chain. The

likely source is oily ballast washings from petroleum tankers (Atwood et al., 1987/88).

9.4 Cities

The pollution impacts of cities in the sub-region are mainly due to chronic low-level

discharges either directly or via rivers to the marine environment. The main point sources

of aquatic pollution are from domestic sewage and industrial effluents. Of these sources,

domestic sewage is the more important. Most urban areas have centralised sewage

treatment facilities whereas rural areas tend to be served by septic tanks or pit latrines. In

the islands the percentage of the population which resides in urban areas is generally high

being less than 34% in only two islands, so that potentially most domestic sewage finds

its way into treatment facilities. However, poor maintenance of these treatment facilities

has led to localised inputs of sewage into the marine environment in some parts of the

Eastern Caribbean. The percentage of domestic wastes currently treated is unknown, but

the high proportion of poor or non-functional sewage treatment plants (17-100%) is a

cause for concern (Table 7).


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Industrial effluents are a more limited problem as except for Trinidad industrial activity in

the islands is minor and largely based on sugar, alcohol, soft drinks and food processing.

In most cases the small and medium size manufacturing industries are in urban areas and

discharge their effluents into surface drains, rivers or the sea with little treatment. As a

result waste loads (especially BOD, total suspended solids and total nitrogen) from

industrial sources are a major problem particularly in Barbados and on the island of

Trinidad.

10.0 PROTECTIVE MEASURES

The management of the marine and coastal areas of the Lesser Antilles is characterised by

piecemeal efforts outside of the framework of integrated coastal area management plans.

In every instance the legal framework exists but the approach usually taken is either not to

designate marine protected areas MPA’s) at all or to designate them with little attempt at

implementation of management. A phenomenon referred to as ‘paper parks’. Of the 16

sites so designated in the region together with 15 other coastal areas earmarked for

protection (Table 8), only 3 appear to be fully managed at present. This suggests that

about 90% of these areas may not be adequately managed. This assessment appears to be

much worse than that reported a decade previously by the Organisation of American

States. At that time the Marine Islands Nature Reserve in St. Lucia and the Barbados

Marine Reserve were rated as fully managed but more recent information suggests that

they no longer warrant this status (van’t Hof, 1994). Interestingly the few areas, which

appear to be fully managed, are operated either by an agency of a colonial government as

in the U.S.Virgin Islands or by a non-governmental organisation as in Saba and the

British Virgin Islands. Lack of implementation of protected area management has been

attributed to a composite of lack of funding, lack of trained personnel and lack of public

support (van’t Hof, 1994). The region has the technical resources to solve these problems

but most international assistance programs draw on human resources from outside the


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region. This approach slows the long-term solution, which should be based on developing

indigenous capacity. It is difficult for individuals from outside the region to appreciate the

requirements of marine resource management on the insular scale where less than a

handful of professional staff are available on each island. If the limited expertise is pooled

then the area may be amenable to the large marine ecosystem (LME) approach to

managing marine resources. However, since this LME includes the territorial waters of

more than 14 countries, the effectiveness of this management tool is dependent on the co-

operation of all the bordering countries.

The Lesser Antillean countries are also participants in several important international

conventions and programs which are geared to protect the marine and coastal

environment (Table 9). Due to its intensive maritime activities and sensitive marine

environment, the wider Caribbean Region has been designated a “Special Area” under

Annex V of the International Convention for the Prevention of Pollution from Ships –

MARPOL 73/78. The Convention imposes severe waste-disposal restrictions on ships

using the Caribbean Sea and requires ports to provide reception facilities on land.

However, before special area status can be officially activated, the IMO’s Marine

Environment Protection Committee has to be notified that “sufficient and adequate”

reception facilities exist in the region. These shore-based facilities must be able to accept

the waste that will no longer be discharged into the sea. Governments are also required to

enact domestic legislation to give effect to the provisions of the treaty. Although most of

the countries in the Eastern and Wider Caribbean are signatories to the Convention, to-

date they have collectively done little to discharge their obligations under the treaty.

Twelve months after they do, the regime can actually start being applied. Only then will

ships transiting the Caribbean be legally prohibited from dumping virtually anything at all

overboard.


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Since 1990, most governments of the region have also been signatories to the Cartagena

Convention. Under this Convention a Protocol on Specially Protected Areas and Wildlife

(SPAW) for the Caribbean has been adopted as part of the Caribbean Environment

Program (CEP). Similar provisions for the designation of protected areas and species are

also found in the Convention on Biological Diversity (arising out of the 1992 Earth

Summit in Rio de Janeiro) and the Convention on Wetlands of International Importance

Especially as Waterfowl Habitat (Ramsar). A common theme in the sub-region is that the

domestic legislation, which all these Conventions require, has not been enacted. The

islands will have to significantly increase their environmental protection efforts if they are

to stem the tide of pollution and natural resource depletion.

REFERENCES

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Agard, J. B. R., Gobin, J., Warwick, R. M. (1993). Analysis of marine macrobenthic community structure in relation to natural and man induced perturbations in a tropical environment (Trinidad, West Indies). Mar. Ecol. Prog. Ser. 92; 233-243.

Agard, J.B.R., R.H. Hubbard, J.K. Griffith (1996). The relation between productivity, disturbance and the biodiversity of Caribbean phytoplankton: applicability of Huston’s dynamic equilibrium model. J. Exp. Mar. Bio. Ecol. 202: 1-17.

Atwood, D. K., F.J. Burton, J.E. Corredor, G.R. Harvey, A.J. Mata-Jimenez, A. Vasquez-Botello and B.A.Wade (1987/88). Petroleum pollution in the Caribbean. Oceanus 30(4): 25-32.

Bacon , Peter R. (1993). Mangroves in the Lesser Antilles, Jamaica and Trinidad and Tobago. In: Conservation and sustainable utilization of mangrove forests in Latin America and African Regions, Part 1: Latin America, edited by L.D. Lacerda, mangrove ecosystems technical reports, Vol. 2, International Society for Mangrove Ecosystems and International Tropical Timber Organization, 155-193.

Bhattathiri, P. M. A., Wagh, A. B., Chow, B. A., Hubbard, R., Mohammed, A. (1991). Primary production and phytoplankton biomass from the Caribbean Sea. Caribb. Mar. Stud. 2(1 & 2): 45-53.


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CARICOMP Program (1997). Structure and productivity of mangrove forests in the Greater Caribbean region. Proc 8th Int Coral Reef Sym 1: 669-672.

CARICOMP (1997a). Variation in ecological parameters of Thallasia Testiudinum across the CARICOMP network. Proc 8th Int Coral Reef Sym 1: 663-668.

CARICOMP (1997b). Caribbean marine productivity (CARICOMP): A research and monitoring network of marine laboratories, parks, and reserves. Proc 8th Int Coral Reef Sym 1; 641-646.

Fong, P; Lirman, D. 1995. Hurricanes cause population expansion of the branching coral Acropora palmata (Scleractinia): wound healing and growth patterns of asexual recruits. Mar. Ecol. 16(4), 317-335.

Gumbs, F. (1981). Agriculture in the wider Caribbean. Ambio 10(6), 335-339.

Heileman, L.I. and Siung-Chang, A.(1990). An analysis of fish kills in coastal and inland waters of Trinidad and Tobago, West Indies, 1976-1990. Caribb. Mar. Stud. 1(2):126-136.

Kumar, S. P., Murty, V. S. N., Khan, A. A., Jones, M. A., Wagh, A. B. and Desai, B. N. (1991). Hydrographic characteristics and circulation in the Caribbean Sea during April and May 1990. Caribb. Mar. Stud. 2(1 & 2): 69-80.

Lessios, H. A. (1988). Mass mortality of Diadema antillarum in the Caribbean: What have we learned ? Ann. Rev Ecol. Syst. 19:371-393.

Muller-Karger, F .E., McClain, C. R. and Richardson, P. L. (1988). The dispersal of the Amazon’s water. Nature 333(6168): 56-59.

Muller-Karger, F. L. and Varela, R. J. (1989). Influjo del Rio Orinoco en el mar: observaciones con el CZCS desde el espacio. Mem. Soc. Nat. La Salle 49(131-132); 361-390.

Richardson, P. L., Hufford, G., Limeburner, R. (1994). North Brazil Current Retroflection Eddies. J. Geophys. Res. 99: 5081-5093.

Rogers, C. S., Suchanek, T.H. and Pecora, F. A. (1982). Effects of hurricanes David and Frederick (1979) on shallow Acropora palmata reef communities: St. Croix, U.S. Virgin Islands. Bull. Mar. Sci. 32(2): 532-548.

Smith, A. H. and Berkes, F. (1991). Solutions to the “Tragedy of the Commons”: Sea urchin management in St. Lucia, West Indies. Environmental Conservation 18(2):28-31.

Stansfield, K. L., Bowman, M. J., Fauria, S. J. and Wilson, T. C. (1995). Water mass and coastal current variability near Barbados, West Indies. J. Geophys. Res., 100: 24819-24830.


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Towle, J. A. and Towle, E. L. (1991). Environmental Agenda for the 1990’s: A Synthesis of the Eastern Caribbean country profile series. Caribbean Conservation Association/Island Resources Foundation. 71pp.

van’t Hof, T. (1994). Resolving common issues and problems of marine protected areas in the Caribbean. Caribbean Conservation Association. 58pp.

Ward, N.F.R. (1987/88). The whalers of Bequia. Oceanus 30(4): 89-93.

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