THERMAL INFRARED INDICATIONS OF SUBMARINE GROUNDWATER DISCHARGE (SGD) IN THE NORTHERN COAST OF JAMAICA

Aerial thermal Infrared (TIR) imagery was used in Jamaica to identify submarine groundwater discharge (SGD) which is now widely recognized as an important pathway in the transport of freshwater and dissolved nutrients to the coastal ocean. Thermal differences in warm tropical coastal waters and cooler groundwater discharge were mapped with a FLIR Systems T400 TIR camera at altitudes between 1000ft and 3000ft. Aerial surveys were conducted in September 2016 and January 2017 along the northern coast of Jamaica at four sites: Discovery Bay, Ocho Rios, Turtle Crawle, and Cold Harbor. In Discovery Bay TIR imagery shows thermal differences of 1° – 2°C in small plumes around the Discovery Bay Marine Lab. Seepage meter measurements made in Discovery Bay gave SGD flux rates of up to 115 cm/d and as little as 5 cm/d. TIR imagery of Ocho Rios disclosed a distinct plume of cool water (~1°C cooler than ambient temperatures) indicative of a concentrated source of SGD. Cool-water plumes were found in Turtle Crawle and Cold Harbour reaching up to 3°C cooler than ambient surface waters. SGD occurs along the northern embayed coast of Jamaica as both concentrated, submerged springs and as a diffuse flow of groundwater and should be expected to be fairly ubiquitous, but has only been documented in Discovery Bay. The location of SGD are important in small island developing states (SIDS) like Jamaica, where the marine economy (fishing, ecotourism) depends upon maintaining the quality of the coastal ocean despite pressures from increasing coastal development, pollution, and overfishing. Identifying the strength and location of SGD along the Jamaican coast can provide a strategic road map to regulating and maintaining the quality of coastal ocean environments.