Using fatty-acid profile analysis as an ecologic indicator in the management of tourist impacts on marine wildlife: a case of stingray-feeding in the Caribbean.

Feeding marine wildlife as a tourism experience has become a popular means by which to attract both people and wildlife, although management efforts are still in their infancy. "Stingray City Sandbar" in the Cayman Islands, where visitors can hand feed free-ranging Southern Stingrays (Dasyatis americana), is a world-famous attraction currently undergoing visitor and wildlife management. One plan is to decrease the amount of nonnatural food provided by tourists with the intention of decreasing stingray habituation to the artificial food source and promoting stingray health. However, the effectiveness of this action is uncertain given that neither the extent of squid composition in the stingray diet nor the degree of nutrient similarity between the fed and natural diets is unknown. We used fatty acid (FA) profile analysis to address these questions by assessing the serum nonesterified FA composition of fed and unfed stingrays around the island and compared them with FA profiles of (1) the provisioned food source (squid) and (2) other warm- and cold-water elasmobranchs (sharks and rays). Our results indicated that fed stingrays were distinct. The FA profiles of the fed stingray population were expressly different from those of the unfed populations and showed a remarkable similarity to the FA composition of squid, suggesting that squid is the main food source. The tropical fed stingrays also exhibited essential FA ratios, specific to both species and habitat, comparable with those of elasmobranchs and squid from cold-water environs, implying that the provisioned food does not provide a similar nutritional lipid composition to that eaten in the wild. Our results suggest that FA profiles are a valuable indicator for the management and monitoring of fed Southern Stingrays because they can be used to assess differences in diet composition and provide an index of nutritional similarity. Our findings are currently being used by Caymanian stakeholders in designing practical management actions for their wildlife attraction.

Finding the tradeoffs between the reserve design and representation.

Many reserve selection tools have been created to solve the minimum representation problem, selecting the least costly set of sites such that all conservation surrogate targets are met. However, there are practical problems and risks associated with this method for finding reserve network alternatives, including the treatment of persistence-promoting design considerations as secondary objectives. Here, reserve networks are generated for a hypothetical landscape where the objectives are to maximize representation and to maximize conformance with persistence-promoting design principles, subject to a constraint on the number of sites in the networks. The efficiency of potential networks is calculated as the total number of species captured in the included sites. Effectiveness is measured as a function of the size of individual patches, total reserve size, and extent of interpatch connectivity. A series of tradeoff curves are produced showing the nondominated compromise alternatives between representation and design for organisms with varying dispersal capabilities. Each alternative comprises a list of selected sites and covers species, as well as the identities and locations of the interpatch edges connecting the sites. Potential ways to use the results are discussed.