Ecological risk assessment of the introduction of exotic carrageenophytes in the tropical Western Atlantic

摘要

The potential risks of cultivating carrageenophyte genera for commercial purposes in the circumtropical belt are debated. However, species introductions of two such genera, Kappaphycus Doty and Eucheuma J. Agardh, have been reported in 30 different locations in this region over the last 30 years. On several occasions, these introductions did not adequately evaluate potential environmental risks or were conducted without approval from local regulatory bodies. In the present paper, a working protocol is proposed for the quarantine and assessment of the possible effects of the introduction of Kappaphycus alvarezii and Kappaphycus striatus to shallow marine ecosystems of the tropical Western Atlantic. This protocol is based on field data following from the introduction of eucheumoids onto the Cuban shelf in the early 1990s. It was demonstrated that the propagation of either carrageenophyte in oligotrophic waters of the Cuban Archipelago did not pose a potential risk to the region's biodiversity due to the synergic combination of high herbivory and low rates of growth. Physical features of the substrate and depth were the most important regulators of grazing. These environmental conditions restrict potential cultivation sites in the Cuban Archipelago to a few small regions where nutrient pulses are well established. In these areas, when the canopy of cultivated carrageenophytes is sufficiently high, a significant effect on benthic communities is observed. In consideration of the need to protect places with high intrinsic value, this fact should be considered during site selection.