PILOT CULTURE OF RED SEAWEEDS (RHODOPHYTA) IN PORTETE BAY, LA GUAJIRA, COLOMBIA

Abstract

A seaweed pilot culture was developed in Portete bay, La Guajira, Colombia, between July 2005 and June 2006. The aim of this study was to evaluate the potential of this activity as a productive alternative to coastal communities thriving in the region. One hundred fourteen kilograms of the red algae Gracilaria cervicornis, Hydropuntia cornea, Hypnea musciformis and Grateloupia sp. were attached to polypropylene ropes and cylindrical meshes, at two sites of the bay. Gracilaria cervicornis had relative growth rates (RGR) between 0.1 % day-1 and 1.22 % day-1, with a mean of 0.44 % day-1, strong epiphytism and high loss rates. Hydropuntia cornea had a mean RGR of 0.91 % day-1 varying between 0.02 % day-1 and 3.5 % day-1 at site one, while at site two it had an average RGR of 0.97 % day-1 with a range between 0.03 % day-1 to 4.1 % day-1 with the maximum value recorded in February 2006. Small sized fragments exhibited the best RGR and biomass increase in comparison to larger fragments. Hypnea musciformis and Grateloupia sp. did not fare well under culture conditions due to their fragility. Environmental factors such as temperature and salinity had great variation in time, but no correlation was evident with RGR. The greatest RGR and epiphytism reduction were observed during the dry season where minimum temperatures were registered and there was an increase in nutrient availability due to a seasonal upwelling event. Different factors, such as water motion, nutrient concentration, temperature, salinity, herbivory, and epiphytism, exert some influence on seaweed growth, although is necessary to perform a complete characterization of physicochemical parameters in order to assess the bay’s productivity. It is also necessary to develop experiments aimed at reducing the incidence of different factors in the cultures. The RGR of some local algae species reported in this study suggest that Portete bay has adequate conditions to develop seaweed culture but, in order to do so, it is necessary to improve some of the culture techniques.