Natural bankside vegetation and clean clear water of the Guanapo River.

About three-quarters of the water we use to supply domestic, industrial, commercial and irrigation needs in Trinidad and Tobago is drawn from rivers and streams. At the same time there is a wide range of activities in and around these rivers: urbanisation, industrial and commercial development, fishing, river ‘limes’ are all taking a toll on this invaluable resource.

In addition to providing water, rivers in their natural state provide a variety of functions: flood water storage and flood protection, biodiversity support, social activities such as recreation (the ever popular ‘river lime’) and the economic spin-offs of these in rural areas. Culturally, rivers are important for religious rituals such as the annual Hindu festival Ganga Dharaa.

Another less recognised value is the extensive international research on freshwater fish such as the guppy in Northern Range rivers where teams of researchers from North America and the United Kingdom visit regularly to study the behaviour and private lives of these fish in their natural environments. Such activities generate employment and income and allow for transfer of knowledge.

A 1998 Biodiversity Support Program report on the freshwater biodiversity of the Latin American and the Caribbean region highlight Trinidad and Tobago’s rivers as being locally distinctive and endangered and therefore a priority area for conservation at the regional scale.

Rivers throughout Trinidad and Tobago vary remarkably in physical form and the diversity life they support. They range from narrow upper course torrents with ‘jumping guabin’ hunched down in small pools, to slow-moving muddy lowland streams with caiman, turtles, many species of fish and innumerable aquatic insects.

PhD researcher Lorraine Maharaj proposed that Trinidad and Tobago’s rivers can be assigned to 3 discernable ‘ecoregions’ based on their substrate (e.g. boulder, gravel, clay) and discharge (rate of water flow). They are (1) Tobago, (2) North and North-East Trinidad, and (3) Central and South Trinidad. This is consistent with the background variation in topography and geology of these areas.

Diverse river environments could account for our notably high biodiversity. Dawn Phillip’s updated freshwater fish inventory now stands at 37 to 40 species of true freshwater fish (not including brackish or migratory species). The list of crabs and freshwater shrimp surveyed by Wayne Rostant now stands at 43 species. More than 60 species were identified in a survey of one aquatic insect group and almost half were new to science. These are remarkable numbers for such small islands and reflect our favourable geographical position close to the South American mainland.

Clearly, adequate supplies of clean freshwater in Trinidad and Tobago are necessary not only for human survival and economic development but also for maintenance of productive and species-rich aquatic ecosystems that are of importance to the region.