Percepción comunitaria sobre arrecifes coralinos en Golfo Dulce: bases para integración social en programas de restauración

Introducción: Enfrentar la acelerada degradación de arrecifes coralinos requiere una acción integrada en múltiples niveles sociales y ecológicos. A escala local se debe incluir la participación activa de los usuarios de los recursos. Objetivo: evaluar el conocimiento y percepción local sobre los arrecifes coralinos en Golfo Dulce, y así generar bases para la integración social en la restauración coralina. Métodos: se realizaron 183 entrevistas en siete comunidades costeras del Golfo Dulce entre septiembre del 2016 y marzo del 2017. Los entrevistados se clasificaron en: (1) Pesca artesanal (PA) = 57 entrevistados, (2) Turismo (T) = 62, y (3) Otros (O) = 64. La primera parte de la entrevista fue de conocimiento y se asignó una nota basada en respuestas correctas. Según la nota se clasificó como informado, información media o desinformado. La segunda parte se basó en escalas de percepción sobre: (I) visitación, (II) factores que dañan los arrecifes coralinos, (III) medidas de manejo y (IV) salud de recursos marinos en Golfo Dulce. Resultados: El grupo T tuvo el mayor porcentaje de entrevistados informados = 42 % y el grupo O de desinformados = 37 %. La segunda parte fue percepción, más del 50 % de PA y T consideran que la visita es frecuente. La sedimentación y contaminación por agroquímicos fueron identificados por más del 60 % de PA y T como la principal amenaza. El 35 % de PA y el 40 % de T perciben las boyas fijas como la mejor medida para el Golfo Dulce. La restricción de visitas fue la medida con menor aceptación. El 60 % de los entrevistados de PA y T consideran que los recursos marinos del golfo estarán peor que en la actualidad. Conclusiones: Estos resultados confirman la importancia de comprender el conocimiento y la percepción de los usuarios de los arrecifes de coral en los procesos participativos y educativos en la restauración y conservación de los arrecifes de coral.

Introduction: Addressing the accelerated coral reefs degradation requires integrated action at multiple social and ecological scales. At local level, active participation of the main users must be included. Objective: To evaluate local knowledge and perception about coral reefs in Golfo Dulce to generate bases for social integration in coral restoration. Methods: 183 interviews were conducted in coastal communities in Golfo Dulce, between September 2016 and March 2017. The interviewees were classified as: (1) Artisanal fishing (PA) = 57 interviewees, (2) Tourism (T) = 62, and (3) Others (O) = 64. The first part of the interview was about knowledge and a grade was assigned based on correct answers. According to the grade, they were classified as informed, medium information or uninformed. The second part was based on perception scales on: (I) visitation, (II) factors that damage coral reefs, (III) management measures, and (IV) health of marine resources in Golfo Dulce. Results: Group T had the highest percentage of informed interviewees = 42 % and group O uninformed = 37 %. The second part was perception, more than 50 % of PA and T consider that the visit is frequent. Sedimentation and contamination by agrochemicals were identified by more than 60 % of PA and T as the main threat. 35 % of PA and 40 % of T perceive permanent buoys as the best measure for the Golfo Dulce. The visitation restriction was the measure with the least acceptance. 60 % of the interviewees of PA and T consider that the marine resources of the gulf will be worse than today. Conclusions: These results confirm the importance of understading coral reefs users knowledge and perception in participatory and educational processes in coral reef restoration and conservation.

Extreme temperature events will drive coral decline in the Coral Triangle.

In light of rapid environmental change, quantifying the contribution of regional- and local-scale drivers of coral persistence is necessary to characterize fully the resilience of coral reef systems. To assess multiscale responses to thermal perturbation of corals in the Coral Triangle (CT), we developed a spatially explicit metacommunity model with coral-algal competition, including seasonal larval dispersal and external spatiotemporal forcing. We tested coral sensitivity in 2,083 reefs across the CT region and surrounding areas under potential future temperature regimes, with and without interannual climate variability, exploring a range of 0.5-2.0°C overall increase in temperature in the system by 2054. We found that among future projections, reef survival probability and mean percent coral cover over time were largely determined by the presence or absence of interannual sea surface temperature (SST) extremes as well as absolute temperature increase. Overall, reefs that experienced SST time series that were filtered to remove interannual variability had approximately double the chance of survival than reefs subjected to unfiltered SST. By the end of the forecast period, the inclusion of thermal anomalies was equivalent to an increase of at least 0.5°C in SST projections without anomalies. Change in percent coral cover varied widely across the region within temperature scenarios, with some reefs experiencing local extinction while others remaining relatively unchanged. Sink strength and current thermal stress threshold were found to be significant drivers of these patterns, highlighting the importance of processes that underlie larval connectivity and bleaching sensitivity in coral networks.

Larval connectivity across temperature gradients and its potential effect on heat tolerance in coral populations.

Coral reefs are increasingly exposed to elevated temperatures that can cause coral bleaching and high levels of mortality of corals and associated organisms. The temperature threshold for coral bleaching depends on the acclimation and adaptation of corals to the local maximum temperature regime. However, because of larval dispersal, coral populations can receive larvae from corals that are adapted to very different temperature regimes. We combine an offline particle tracking routine with output from a high-resolution physical oceanographic model to investigate whether connectivity of coral larvae between reefs of different thermal regimes could alter the thermal stress threshold of corals. Our results suggest that larval transport between reefs of widely varying temperatures is likely in the Coral Triangle and that accounting for this connectivity may be important in bleaching predictions. This has important implications in conservation planning, because connectivity may allow some reefs to have an inherited heat tolerance that is higher or lower than predicted based on local conditions alone.

The impact of ENSO on coral heat stress in the western equatorial Pacific.

The Coral Triangle encompasses an extensive region of coral reefs in the western tropical Pacific with marine resources that support millions of people. As in all other reef regions, coral reefs in the Coral Triangle have been impacted by anomalously high ocean temperature. The vast majority of bleaching observations to date have been associated with the 1998 La Niña phase of ENSO. To understand the significance of ENSO and other climatic oscillations to heat stress in the Coral Triangle, we use a 5-km resolution Regional Ocean Model System for the Coral Triangle (CT-ROMS) to study ocean temperature thresholds and variability for the 1960-2007 historical period. Heat-stress events are more frequent during La Niña events, but occur under all climatic conditions, reflecting an overall warming trend since the 1970s. Mean sea surface temperature (SST) in the region increased an average of ~ 0.1 °C per decade over the time period, but with considerable spatial variability. The spatial patterns of SST and heat stress across the Coral Triangle reflect the complex bathymetry and oceanography. The patterns did not change significantly over time or with shifts in ENSO. Several regions experienced little to no heat stress over the entire period. Of particular interest to marine conservation are regions where there are few records of coral bleaching despite the presence of significant heat stress, such as in the Banda Sea. Although this may be due to under-reporting of bleaching events, it may also be due to physical factors such as mixing and cloudiness, or biological factors that reduce sensitivity to heat stress.

Coral reef habitat response to climate change scenarios.

Coral reef ecosystems are threatened by both climate change and direct anthropogenic stress. Climate change will alter the physico-chemical environment that reefs currently occupy, leaving only limited regions that are conducive to reef habitation. Identifying these regions early may aid conservation efforts and inform decisions to transplant particular coral species or groups. Here a species distribution model (Maxent) is used to describe habitat suitable for coral reef growth. Two climate change scenarios (RCP4.5, RCP8.5) from the National Center for Atmospheric Research's Community Earth System Model were used with Maxent to determine environmental suitability for corals (order Scleractinia). Environmental input variables best at representing the limits of suitable reef growth regions were isolated using a principal component analysis. Climate-driven changes in suitable habitat depend strongly on the unique region of reefs used to train Maxent. Increased global habitat loss was predicted in both climate projections through the 21(st) century. A maximum habitat loss of 43% by 2100 was predicted in RCP4.5 and 82% in RCP8.5. When the model is trained solely with environmental data from the Caribbean/Atlantic, 83% of global habitat was lost by 2100 for RCP4.5 and 88% was lost for RCP8.5. Similarly, global runs trained only with Pacific Ocean reefs estimated that 60% of suitable habitat would be lost by 2100 in RCP4.5 and 90% in RCP8.5. When Maxent was trained solely with Indian Ocean reefs, suitable habitat worldwide increased by 38% in RCP4.5 by 2100 and 28% in RCP8.5 by 2050. Global habitat loss by 2100 was just 10% for RCP8.5. This projection suggests that shallow tropical sites in the Indian Ocean basin experience conditions today that are most similar to future projections of worldwide conditions. Indian Ocean reefs may thus be ideal candidate regions from which to select the best strands of coral for potential re-seeding efforts.

Ocean acidification: the other CO2 problem.

Rising atmospheric carbon dioxide (CO2), primarily from human fossil fuel combustion, reduces ocean pH and causes wholesale shifts in seawater carbonate chemistry. The process of ocean acidification is well documented in field data, and the rate will accelerate over this century unless future CO2 emissions are curbed dramatically. Acidification alters seawater chemical speciation and biogeochemical cycles of many elements and compounds. One well-known effect is the lowering of calcium carbonate saturation states, which impacts shell-forming marine organisms from plankton to benthic molluscs, echinoderms, and corals. Many calcifying species exhibit reduced calcification and growth rates in laboratory experiments under high-CO2 conditions. Ocean acidification also causes an increase in carbon fixation rates in some photosynthetic organisms (both calcifying and noncalcifying). The potential for marine organisms to adapt to increasing CO2 and broader implications for ocean ecosystems are not well known; both are high priorities for future research. Although ocean pH has varied in the geological past, paleo-events may be only imperfect analogs to current conditions.

Poorly cemented coral reefs of the eastern tropical Pacific: possible insights into reef development in a high-CO2 world.

Ocean acidification describes the progressive, global reduction in seawater pH that is currently underway because of the accelerating oceanic uptake of atmospheric CO(2). Acidification is expected to reduce coral reef calcification and increase reef dissolution. Inorganic cementation in reefs describes the precipitation of CaCO(3) that acts to bind framework components and occlude porosity. Little is known about the effects of ocean acidification on reef cementation and whether changes in cementation rates will affect reef resistance to erosion. Coral reefs of the eastern tropical Pacific (ETP) are poorly developed and subject to rapid bioerosion. Upwelling processes mix cool, subthermocline waters with elevated pCO(2) (the partial pressure of CO(2)) and nutrients into the surface layers throughout the ETP. Concerns about ocean acidification have led to the suggestion that this region of naturally low pH waters may serve as a model of coral reef development in a high-CO(2) world. We analyzed seawater chemistry and reef framework samples from multiple reef sites in the ETP and found that a low carbonate saturation state (Omega) and trace abundances of cement are characteristic of these reefs. These low cement abundances may be a factor in the high bioerosion rates previously reported for ETP reefs, although elevated nutrients in upwelled waters may also be limiting cementation and/or stimulating bioerosion. ETP reefs represent a real-world example of coral reef growth in low-Omega waters that provide insights into how the biological-geological interface of coral reef ecosystems will change in a high-CO(2) world.