Kingston Harbour, Jamaica ÂŠ an Overview

BULLETIN OF MARINE SCIENCE, 73(2): 249–255, 2003 KINGSTON HARBOUR, JAMAICA — AN OVERVIEW Ivan Goodbody Kingston Harbour, Jamaica (Fig.1; Plate 1), is often considered to be one of the finest natural harbors in the world. It is situated on the south coast of Jamaica at 17º57' N, 76º48' W. The harbor is an elongated bay, or lagoon, extending 16.5 km east–west and 6.5 km north–south with a total surface area of approximately 51 km2 (Wade, 1976a). The city of Kingston, comprised of industrial, commercial and residential developments lies to the north of the harbor and at the western end are modern residential developments of about 10,000 homes, Portmore and Independence City. In its original state the harbor was contiguous at its western margin with a shallow embayment, Hunts Bay. In 1967 the mouth of this bay was partially occluded by a solid causeway with a narrow bridge to permit continued water exchange between harbor and bay. The details of this causeway and its consequences are discussed in Goodbody (1968,1970) and Wade (1976a). The southern margin of the harbor is bounded by a shingle spit, the Palisadoes, built by long- shore drift of sediments tying together a number of derelict coral cays to form a 15 km long tombolo (Goreau and Burke, 1966; Hendry, 1978). The entrance to the harbor is a 2 km wide channel in the southwest corner (Wade, 1976a) and this leads naturally into a 12 m deep channel, which curves around the northwest side of the harbor providing navi- gable access to its inner basins. This channel, usually referred to as ‘the ship channel,’ is a natural formation, probably maintained originally by natural water circulation (cf. Goodbody, 1968,1970), but in recent years the Port Authority has engaged in maintenance dredging to prevent undue sedimentation and permit the continued access of large ships to the Port of Kingston. At the time of writing (early 2002), renewed dredging activity and land reclamation was being undertaken not only to enlarge the channel, but also to expand the port facilities. Some of the spoil material was being used to reclaim land in the northeast corner of Hunts Bay and in a small lagoon between Fort Augusta and the causeway, to the detriment of artisanal fisheries in both locations. It is impossible at this time to forecast what will be the final environmental status of the western end of the harbor. The small town and fishing settlement of Port Royal is situated on the eastern margin of the harbor mouth and is the location of one of the University of the West Indies’ two marine research laboratories. Other small fishing communities also exist on the north shore of the harbor, notably at Greenwich in the west and Rae Town in the east. Port Royal was originally an island, but was finally joined, probably by natural forces, to the rest of the tombolo around 1734 (Hendry, 1978). During their occupation of Jamaica, the Spaniards built fortifications at Port Royal naming it ‘Caguay’. After 1655, the British developed a commercial center and naval base at Port Royal. The Naval Dockyard remained active until after the First World War and is now the site of a modern small craft marina. Goodbody (1970) and Wade (1976a) defined two regions within the harbor, the Outer Harbor comprising a deep basin just inside the mouth and lying between Port Royal on the east and Port Henderson in the west, and the Inner Harbor extending along the main east–west axis of the harbor (Fig.1). According to Wade (loc. cit.) the maximum depth of the Outer Harbor just inside the mouth is about 18.3 m; the Inner Harbor is fairly uniform 249 250 BULLETIN OF MARINE SCIENCE, VOL. 73, NO. 2, 2003 Figure 1. Map of Kingston Harbour showing the major features. in depth (c.15 m.) with occasional shoals covered by turtle grass (Thalassia testudinum). Formerly, beds of bivalve molluscs (Arca imbricata) were found in this turtle grass, but they have not been recorded recently. The eastern end of the Inner Harbor forms a deep basin about 18 m in depth with a soft muddy sediment on the bottom, often giving rise to an anoxic benthic environment (Wade et al., 1972). Goodbody (1970) and Wade (1976a) named this region of the harbor ‘Upper Basin’ (Fig. 1). There is no present day open connection, or channel across the Palisadoes tombolo between the Upper Basin and the open sea to the south, but historically it has been breached on a number of occasions, the most recent recorded event being in the late eighteenth century (Hendry, 1978). In recent times during very stormy weather, the sea has washed over the tombolo between Harbour Head and the International Airport, but no permanent breach has occurred. However, at times the water in the Upper Basin adjacent to the tombolo is very clear and suggests that water may be passing through the base of the tombolo from the open ocean to the harbor and being filtered in the process. Detailed study of the system might reveal the extent of any water exchange. It is likely that in its original state, Kingston Harbour was surrounded by mangrove forest, but only small remnants of that forest remain today. The most significant remain- ing mangrove forest is on the southern shore of the harbor just to the east of Port Royal (Plate 1). The topography and general ecology of this forest has been documented by Alleng (1990). Details of the lagoons and waterways are given elsewhere in this volume (Goodbody, 2003). Until the construction of the causeway in 1965, a large stand of mangrove forest remained on the western shore of Hunt’s Bay enclosing a large lagoon, Dawkins Pond, which was a source of shrimp for the artisanal fishery and was also an GOODBODY: OVERVIEW OF KINGSTON HARBOUR, JAMAICA 251 Plate 1. Kingston Harbour showing (A) Hunts Bay, (B) the Norman Manley International Airport, (C) the Port Royal mangroves. important nursery ground for finfish. Most of this forest was destroyed during construction of Portmore and Independence City during the 1960s. A third important remnant of the old mangrove forest existed, until recently, on the northern shore of the Palisadoes tombolo in the vicinity of the present international airport. Much of this forest was destroyed during the construction of the modern airport between 1950–1960, and later by the construction of a marina for the Royal Jamaica Yacht Club and the Maritime Institute of Jamaica. All of these mangrove forests must have contributed significantly to the natural maintenance of nutrient balance and oxida- tive breakdown of organic materials, and their progressive destruction over a period of years is likely to have contributed to the recent environmental degradation in the harbor. Freshwater inflow into the harbor is intermittent from several different sources de- pending on prevailing weather conditions. Two rivers, the Rio Cobre and the Duhaney River, enter Hunts Bay and a number of storm gullies draining from the urban areas of the city discharge into both Hunt’s Bay and into the Inner Harbor. Wade (1976a) estimated that 662 km2 of land drained directly into Hunts Bay and only 52 km2 drained into the Inner Harbor. Changing land use patterns will have altered these figures since Wade pub- lished his report, but the impact of these input sources remains significant. All such sources are potential carriers of nutrients and other pollutants, ultimately leading to eutrophica- tion and degradation in the water column of the harbor. For a review of the storm gullies and their discharge rates see National Water Commission (1993) and Webber and Wilson Kelly (2003). The two rivers drain from agricultural lands, hence are sources of agro- chemicals including pesticides, while the storm gullies drain from residential and industrial areas of the city and carry solid waste as well as heavy metals and other contami- nants. A further source of contamination is due to the many residential areas of the city 252 BULLETIN OF MARINE SCIENCE, VOL. 73, NO. 2, 2003 that are not connected to a main sewerage disposal system and rely on soak away pits on the premises. The underlying soil is porous over a bed-rock of limestone and the contents of the pits soak through the soil and rock, eventually joining an underground water table leaching both water and dissolved nutrients into the harbor. Steven (1968) reported that by the 1960s, levels of production (measured by radio- carbon uptake) were already high and were in the region of 50 times as high as those encountered in the open ocean outside the harbor. Steven’s work related only to the water column, hence to phytoplankton communities, taking no account of production in seagrass or mangrove communities. The driving force for high levels of production in the harbor is domestic sewage, which for many years has been discharged into the harbor, originally in untreated form and later after being given primary or secondary treatment with varying degrees of success. Wade et al. (1972) used biological indicators to identify the effects of such organic pollution on benthic communities in the harbor, particularly, the development of an abiotic zone in the Upper Basin. The development of abiotic conditions in the benthos of the Upper Basin has also altered the conclusions of Munro (1968), who on the basis of a small trawl survey predicted that there was potential for a small artisanal trawl fishery for shrimp and finfish in the upper basin. Increasing organic pollution in the harbor may, nevertheless, have had beneficial effects on the artisanal fishery, but this remains poorly documented.

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