Beltrán-Rodríguez, Diana M.

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2007 - 200912010 - 20151
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    Conservation biology in benthic reef fishes: population genomics of Opistognathus aurifrons
    (2015) Beltrán-Rodríguez, Diana M.; Appeldoorn, Richard S.; College of Arts and Sciences - Sciences; Schizas, Nikolaos V.; Valdés Pizzini, Manuel; García Sais, Jorge R.; Otero, Ernesto; Department of Marine Sciences; Cruzado, Ivette
    The world oceans are deteriorating at a fast pace with obvious effects on coral reefs, in which at least 50% of coral cover has disappeared. Conservation actions, such Marine Protected Areas are being implemented to alleviate marine ecosystems from stressors and allow populations to restore to healthy levels. Successful networks of MPAs can operate if the space among MPAs is smaller than the dispersal capacity of the species under protection. It is of most importance to estimate the scale of such connectivity among marine populations. Similarly, populations in terrestrial species are often segregated across geography, usually forming independent evolutionary lineages. The addition of such information into conservation in the form of Evolutionary Significant Units (ESU) has helped maintain terrestrial species from extinction and restore natural populations. A similar approach is lacking on coral reef species despite the presence of clearly independently evolving populations. Here we present an in depth analysis of the molecular ecology of the common reef fish Opistognathus aurifrons to aid conservation on coral reefs by providing the scale of connectivity measured as the effective dispersal and the delineation of ESU segregated across the Caribbean. We first designed twelve microsatellite markers with enough power to detect variations in allele frequencies along short geographical distances such across the Mona Passage. Using these markers across 260 individuals, we estimated that the maximum effective dispersal is 10 km. Our detailed data suggest that the distance among MPAs in the network around Puerto Rico is larger than the effective movement of the fish. We found that MPAs exchange migrants likely via intermediate available unprotected habitat. At scales > 100 km connectivity among MPAs decrease, particularly across the Mona Passage, making Mona Island a genetic mosaic of the genetic variation from the eastern and western Caribbean. Driven by the result of small dispersal across fine scales, we tested whether the species is composed of smaller evolutionary significant units spread across the Caribbean. To increase our statistical power from that of microsatellites, we also genotyped individuals across eleven populations for over 18,000 single nucleotide polymorphisms. Our genomic data suggest a large degree of genetic segregation across the Caribbean with all major islands having unique genetic combinations, to the extreme of a monophyletic group in Florida. Our genome-wide analysis indicates that Belize, Florida, Curaçao and Puerto Rico form isolated groups, suggesting there are at least four Evolutionary Significant Units. Estimates of gene flow between pairwise comparisons also suggest that exchange among populations is limited (< 0.1%). Our findings stress the importance to generate a denser MPA network that ensures connectivity within a radius of at least ten kilometers. It also suggests isolated populations do not exchange gametes and have their own independent demographic dynamics, which should also be incorporated into management plans. Reef fish richness is driven by small cryptic benthic species such the yellowhead jawfish, adjusting MPAs to account for the short dispersal in these fishes and incorporating Evolutionary Significant Units into marine conservation, may enhance the maintenance of these vast reef biodiversity.
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    Publication
    Spatio-temporal variation in organic nitrogen and carbon in sediments associated with tropical submerged cage aquaculture
    (2007) Beltrán-Rodríguez, Diana M.; Alston, Dallas E.; College of Arts and Sciences - Sciences; Corredor García, Jorge; Kubaryk, John; Aponte, Nilda E.; Department of Marine Sciences; Alfaro, Mónica
    The diminution of marine fish populations due to over-fishing has stimulated the increase of mariculture activities, including in cages located near the coast. However, these activities may be detrimental influence to marine sediments near the culture sites in coastal sites. The first open-ocean mariculture operation began during 2002 south of Culebra Island, Puerto Rico to culture the fish Rachycentron canadum and Lutjanus analis. The purpose of this study was to evaluate the concentrations of total organic nitrogen (TON), total carbon (TC), and organic matter (OM) in marine sediments near the mariculture site to determine the spatial and temporal dynamics of these nutrients during the first culture period. Results indicate significant differences in the concentration of TON between the cage and control sites. The L. analis cage had a higher mean concentration of TON (0.442 mg N/g) than the R. canadum cage (0.380 mg N/g) and control site (0.300 mg N/g). TC and OM mean concentrations were not significantly different; however, mean TC concentrations had fluctuations similar to those of the mean TON concentrations. TON and TC mean concentrations were significantly different over time, with an increase in the mean TON (0.66 mg N/g) and TC (199 mg C/g) concentrations from April 2003 to August 2003, with a peak in June 2003, which agreed with the increase in the mean monthly feed input at the culture site (12,947 kg) and the increase of wastes because the fish had reached a commercial weight (4.5 kg). Harvesting began in June 2003, so numbers of fish decreased during subsequent months. Organic matter decreased during June, but peaked during October 2003. Although the increase of the nutrient concentration is relatively low compared with other studies, data represent only the first year of mariculture activity. As the company increases the number of cages, this site should be monitored to determine possible increases in nutrient concentrations in the sediments.