Efectos de un emisario submarino de aguas "residuales" urbanas sobre comunidades de octocorales (Octocorallia: Alcyonacea) en Cuba / Effects of a submarine discharge of urban waste on octocoral (Octocorallia: Alcyonacea) communities in Cuba

ABSTRACT

The composition and structure of octocoral communities on coral reefs close to a submarineoutfall were studied at Reparto Flores, west of Havana City, Cuba. Octocoral community changes after thedeployment of the submarine outfall in 2000 were monitored from June 2002 to September 2005, taking asbaseline the data existing before its construction. The area also receives the influence of the polluted river Quibúthat passes through a great part of the west side of the City. Sampling was done by means of SCUBA diving,counting and identifying colonies in situ within a 1 m2 frame that was randomly placed as many times as towarrant stabilized values of Shannon and Weavers heterogeneity index H. In agreement with the availablehydrochemical information, changes in the diversity indexes (Shannon and Weaver`s heterogeneity index H,Pielous equitability index J, and Margalefs species richness index R1), the Herrera-Morenos comparative pollutionindex (ICC), and density of some octocoral species at a depth of 10 m suggest a decrease in the influenceof polluters from 1989 to 2005. Nevertheless, these indicators were affected in 2004 by a sudden intense butbrief colonization of Briareum asbestinum, a species that is not typical of polluted places. At a depth of 20 m,a co-dominance of Plexaura kuekenthali and Eunicea clavigera (resistant and non resistant to pollution, respectively)and an increase of the comparative pollution index (ICC) was observed. The increase of P. kuekenthali,a pollution indicator, suggests a rise in the pollution effect 20 m in depth, because of the recent impact causedby the greater closeness of the outfall mouth 50 m deep. Results corroborate the hypothesis about the pollutionindicator character of P. kuekenthali. However, this could not be explored for Eunicea flexuosa (also considereda pollution-indicator) due to an intensive...(AU)