San Juan, Puerto Rico
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Mercado-Molina A.E.,University of Puerto Rico at San Juan | Ruiz-Diaz C.P.,Sociedad Ambiente Marino | Ruiz-Diaz C.P.,University of Puerto Rico at San Juan | Sabat A.M.,University of Puerto Rico at San Juan
Journal for Nature Conservation | Year: 2015

Acropora cervicornis is one of the principal reef-building organisms in the Caribbean; it is also considered one of the most threatened coral species. Due to its ecological importance and critical status it is the focus of many restoration and management initiatives. However, studies that quantitatively measure the efficacy or feasibility of these efforts are mostly lacking. In this study, nursery-reared fragments of A. cervicornis were transplanted to two reefs in Puerto Rico as part of a reef rehabilitation program, and their survival, growth, and branch production were measured for a year. We also evaluated the effect of this restoration on the dynamics and viability of the fragment populations by means of a simple model. Survival of outplanted fragments surpassed 60%. Colony growth rate varied between 0.20±0.18 and 0.29±0.21cmd-1 (mean±SD) whereas branch production ranged between 7.02±5.72 and 11.86±7.06 (mean±SD) branches per fragment per year. Survival did not vary considerably with respect to fragment size. In contrast, large fragments (≥25cm) grew faster and tended to produce more branches than smaller ones. Model simulations indicate that (1) in the absence of recruitment, and without any subsequent human intervention, restored populations will decrease below a quasi-extinction level of 25% of the initial population size after just 3 years and (2) transplanting at least 20 colony fragments per year (12% of initial population) is sufficient to keep the restored populations above the 25% threshold. We conclude that A. cervicornis may be a feasible species for restoration projects given sustained human intervention and that transplanting fragments of at least 25cm to reefs is an effective restoration protocol that requires minimum effort to maintain a viable restored population of this key reef-building coral. © 2015 Elsevier GmbH.


Mercado-Molina A.E.,University of Puerto Rico at San Juan | Montanez-Acuna A.,University of Puerto Rico at San Juan | Rodriguez-Barreras R.,University of Puerto Rico at San Juan | Colon-Miranda R.,University of Puerto Rico at San Juan | And 4 more authors.
Journal of the Marine Biological Association of the United Kingdom | Year: 2015

The mass mortality suffered by the sea urchin Diadema antillarum between 1983-1984 is considered one of the major causes of coral reef degradation in the Caribbean. Its near disappearance resulted in a disproportionate growth of macroalgae that has led to a 'phase shift' from coral-to-algal dominated reefs. The close relationship between this echinoid and the functioning of coral reef ecosystems makes it imperative to better understand the potential for recovery of its populations. From 2009 to 2011, we assessed the density and size structure of D. antillarum in various reefs where previous population data were available. Results indicate a modest increase in density in all localities with respect to the last time they were surveyed in 2003/2004. Nevertheless, density values are still lower than values reported for the island prior to the die-off. Overall density did not surpass 1.49 ind. per m-2, and did not change considerably during the studied period. Lack of population growth coincided with a lack of juveniles; suggesting that population growth at the studied sites may be limited by the number of individuals recruiting into the juvenile stage. Copyright © Marine Biological Association of the United Kingdom 2014.


Mercado-Molina A.E.,University of Puerto Rico at San Juan | Ruiz-Diaz C.P.,Sociedad Ambiente Marino | Ruiz-Diaz C.P.,University of Puerto Rico at San Juan | Perez M.E.,University of Puerto Rico at San Juan | And 2 more authors.
Coral Reefs | Year: 2015

Populations of Acropora cervicornis have collapsed throughout the Caribbean. This situation has prompted the initiation of many restoration efforts; yet, there are insufficient demographic data and analyses to effectively guide these initiatives. In this study we assessed the spatiotemporal variability of A. cervicornis vital rates. We also developed a population matrix model to (1) evaluate the risk of population extinction, (2) estimate population growth rates (λ) considering different rates of colony fragmentation and fragment survival, (3) determine the demographic transition(s) that contribute the most to spatiotemporal differences in λs, and (4) analyze the effectiveness of outplanting coral fragments of different sizes. The model was parameterized by following the fate of 300 colonies from 2011 to 2013 at two localities in Puerto Rico. Demographic transitions varied spatiotemporally, with a significant interaction between location and time period on colony fate. Spatiotemporal variations in λ were also observed. During the first year, populations exhibited λs below equilibrium (0.918 and 0.948), followed by a dramatic decline at both sites (0.535 and 0.709) during the second year. The lower λs were caused by a decrease in the probability of stasis of large-sized colonies coupled with lack of sexual recruits and a meager contribution of asexual recruitment. Spatial variations in λs were largely due to differences in the probability of medium-sized colonies advancing to the largest size class. The viability analysis forecasts that the populations will reach quasi-extinction levels of 25 % of the initial population size in ≤16 yrs. Numerical simulations indicate that outplanting fragments ≥250 cm in total linear length (TLL) would result in a higher asymptotic population size than outplanting smaller fragments. We argue, however, that transplanting colonies ≤100 cm TLL will be a better management strategy because they can be produced faster and in higher numbers at coral nurseries. © 2015, Springer-Verlag Berlin Heidelberg.


Mercado-Molina A.E.,University of Puerto Rico at San Juan | Ruiz-Diaz C.P.,Sociedad Ambiente Marino | Ruiz-Diaz C.P.,University of Puerto Rico at San Juan | Sabat A.M.,University of Puerto Rico at San Juan
Journal of Experimental Marine Biology and Ecology | Year: 2016

Acropora cervicornis is a threatened Caribbean coral that depends on branch fragmentation to proliferate. Understanding the patterns of branch formation is, therefore, essential for the development of management and conservation initiatives. This study describes branch morphogenesis in 100 colony fragments that were transplanted to two reefs in Puerto Rico that differ in light intensity. Four morphometric variables were measured for one year: internode length, branch growth rate, the number of ramifying branches (mother branches; MB), and the number of branches produced (daughter branches; DB). Branching complexity was also evaluated using two indices: the Horton-Strahler bifurcation ratio (Rb) and the Carrillo-Mendoza branching index (CM-BI). A simple discrete model was constructed to estimate the number of harvestable branches over time. No spatial difference was observed when comparing the development of the primary branches, as the mean internode lengths, the mean extension rates, and the mean number of branches produced did not differ statistically between sites. Likewise, internode lengths in secondary branches did not vary significantly between sites. In contrast, the mean branching and growth rates of secondary branches differed statistically between the two study locations. Significant spatial differences were also observed when comparing the total number of MB and the total number of DB but not for the ratio of DB to MB. The CM-BI was more appropriate than the Rb in describing the branching structure of A. cervicornis. The model provided a good fit to the observed branching dynamics; demonstrating its usefulness as a tool for predicting branch productivity of this species. The implications for restoration activities are discussed. © 2016 Elsevier B.V.


Sabat A.M.,University of Puerto Rico at San Juan | Toledo-Hernandez C.,Sociedad Ambiente Marino
Journal of Marine Biology | Year: 2015

Diseases are a threat to the viability of an increasing number of coral populations. In this study we analyze the effect of infection and recruitment rate on the viability and structure of sea fan (Gorgonia ventalina) populations using a size-based matrix model parameterized with data from field studies. The model predicts that the viability of sea fan populations is strongly influenced by disease incidence and recruitment. Under high recruitment rate, the disease incidence threshold for population viability is 0.12/yr. However, populations with no or low incidence may also go locally extinct given persistent low recruitment. The model also predicts an effect of recruitment on disease prevalence. Everything else being equal, sites with low recruitment will exhibit higher disease prevalence than ones with high recruitment, particularly in medium and large colonies. Elasticity analysis reveals that changes in colony survivorship are likely to have the strongest effect on population growth rate, particularly given low recruitment. We conclude that under current levels of incidence sea fan populations in the Caribbean are not at risk. However, future epizootics are likely to produce local extinctions particularly if coinciding spatially or temporally with low recruitment. © 2015 Alberto M. Sabat and Carlos Toledo-Hernández.


Hernandez-Delgado E.A.,University of Puerto Rico at San Juan | Montanez-Acuna A.,University of Puerto Rico at San Juan | Otano-Cruz A.,University of Puerto Rico at San Juan | Suleiman-Ramos S.E.,Sociedad Ambiente Marino
Revista de Biologia Tropical | Year: 2014

Ecological impacts of military bombing activities in Puerto Rico have often been described as minimal, with recurrent allegations of confounding effects by hurricanes, coral diseases and local anthropogenic stressors. Reef craters, though isolated, are associated with major colony fragmentation and framework pulverization, with a net permanent loss of reef bio-construction. In contrast, adjacent non-bombarded reef sections have significantly higher benthic spatial relief and biodiversity. We compared benthic communities on 35-50 year-old bomb-cratered coral reefs at Culebra and Vieques Islands, with adjacent non-impacted sites; 2) coral recruit density and fish community structure within and outside craters; and 3) early effects of a rehabilitation effort using low-tech Staghorn coral Acropora cervicornis farming. Reef craters ranged in size from approximately 50 to 400m2 and were largely dominated by heavily fragmented, flattened benthos, with coral cover usually below 2% and dominance by non-reef building taxa (i.e., filamentous algal turfs, macroalgae). Benthic spatial heterogeneity was lower within craters which also resulted in a lowered functional value as fish nursery ground. Fish species richness, abundance and biomass, and coral recruit density were lower within craters. Low-tech, community-based approaches to culture, harvest and transplant A. cervicornis into formerly bombarded grounds have proved successful in increasing percent coral cover, benthic spatial heterogeneity, and helping rehabilitate nursery ground functions. © 2014 Universidad de Costa Rica. All rights reserved.


Toledo-Hernandez C.,Sociedad Ambiente Marino | Ruiz-Diaz C.P.,Sociedad Ambiente Marino | Ruiz-Diaz C.P.,University of Puerto Rico at San Juan
Invertebrate Survival Journal | Year: 2014

Corals are among the most ancient extant animals on earth. Currently, coral viability is threatened, due in part to the increased number of diseases affecting them in recent decades. Understanding how the innate immune systems of corals function is important if we want to predict the fate of corals and their response to the environmental and biological changes they face. In this review we discuss the latest findings regarding the innate immune systems of corals. The review is organized following the chronology of steps taken by corals from the initial encounter with a potential pathogen and recognition of threats to the orchestration of a response. We begin with the literature describing the repertory of immune-related receptors involved in the recognition of threats and the subsequent pathways leading to an immune response. We then review the effector responses that eliminate the threats described for corals. Finally, we acknowledge the literature of coral microbiology to access the potential role of microbes as an essential constituent of the coral immune system. © 2014 Universita degli Studi di Modena e Reggio Emilia. All rights reserved.

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