Coral reefs worldwide are threatened by thermal stress caused by climate change. Especially devastating periods of coral loss frequently occur during El Niño‐Southern Oscillation (ENSO) events originating in the Eastern Tropical Pacific (ETP). El Niño‐induced thermal stress is considered the primary threat to ETP coral reefs. An increase in the frequency and intensity of ENSO events predicted in the coming decades threatens a pan‐tropical collapse of coral reefs. During the 1982–1983 El Niño, most reefs in the Galapagos Islands collapsed, and many more in the region were decimated by massive coral bleaching and mortality. However, after repeated thermal stress disturbances, such as those caused by the 1997–1998 El Niño, ETP corals reefs have demonstrated regional persistence and resiliency. Using a 44 year dataset (1970–2014) of live coral cover from the ETP, we assess whether ETP reefs exhibit the same decline as seen globally for other reefs. Also, we compare the ETP live coral cover rate of change with data from the maximum Degree Heating Weeks experienced by these reefs to assess the role of thermal stress on coral reef survival. We find that during the period 1970–2014, ETP coral cover exhibited temporary reductions following major ENSO events, but no overall decline. Further, we find that ETP reef recovery patterns allow coral to persist under these El Niño‐stressed conditions, often recovering from these events in 10–15 years. Accumulative heat stress explains 31% of the overall annual rate of change of living coral cover in the ETP. This suggests that ETP coral reefs have adapted to thermal extremes to date, and may have the ability to adapt to near‐term future climate‐change thermal anomalies. These findings for ETP reef resilience may provide general insights for the future of coral reef survival and recovery elsewhere under intensifying El Niño scenarios.
Long-distance dispersal is believed to strongly influence coral reef population dynamics across the Tropical Pacific. However, the spatial scale and strength at which populations are potentially connected by dispersal remains uncertain. To determine the patterns in connectivity between the Eastern (ETP) and Central Tropical Pacific (CTP) ecoregions, we used a biophysical model incorporating ocean currents and larval biology to quantify the seascape-wide dispersal potential among all population. We quantified the likelihood and determined the oceanographic conditions that enable the dispersal of coral larvae across the Eastern Pacific Barrier (EP-Barrier) and identified the main connectivity pathways and their conservation value for dominant reef-building corals. Overall, we found that coral assemblages within the CTP and ETP are weakly connected through dispersal. Although the EP-Barrier isolates the ETP from the CTP ecoregion, we found evidence that the EP-Barrier may be breached, in both directions, by rare dispersal events. These rare events could explain the evolutionary genetic similarity among populations of pocilloporids in the ecoregions. Moreover, the ETP may function as a stronger source rather than a destination, providing potential recruits to CTP populations. We also show evidence for a connectivity loop in the ETP, which may positively influence long-term population persistence in the region. Coral conservation and management communities should consider eight-key stepping stone ecoregions when developing strategies to preserve the long-distance connectivity potential across the ETP and CTP.
Confronting a sustained coral reef conservation crisis, we need new opportunities to rethink how to protect areas successfully and efficiently in the face of a changing world. We studied the benthic community, including foraminifera, fish community, and genetic connectivity (SSRs and SNPs) of main reef-building corals, Orbicella faveolata and Agaricia undata, along a Non-Protected Area (NPA) reef tract in Barú peninsula, including some isolated banks, near Cartagena and the National Natural Park Corales del Rosario y San Bernando (NNP CRySB), Colombia. The fringing reef track is homogeneous in benthic components, including algae, sponges, and foraminifera between all the studied sites, while corals exhibited differences between sites and depth ranges. Many reef sites sustain between 42.8 and 53% coral cover, which are among the highest recorded in this region, even higher than the nearby NNP. A total of 82 fish species were found, and the Foram Index-FI varies between 2 and 2.5, showing environmental conditions marginal for reef growth. The Barú NPA reef system can be considered spatial refugia under climate change and Anthropocene conditions, including resilient reefs at the mouth of Cartagena Bay (Magdalena River), a place of increased stressing factors. The admixture between NPA and NNP populations, the high coral cover in the NPA, the fish density and composition, the uniqueness of the diapiric banks, and the disturbance resistance are major arguments to protect this reef tract. We suggest designing a co-management scheme to ensure species connectivity, avoid further degradation, and involve different stakeholders.
El reclutamiento coralino permite inferir sobre el estado de salud y la resiliencia del ecosistema arrecifal. El uso de sustratos artificiales in situ facilita evidenciar la llegada de nuevos individuos y/o repoblamiento de corales escleractinios al sistema. El arrecife El Inglés, en Isla Fuerte (Caribe colombiano), está expuesto a la influencia de los ríos Sinú y Magdalena. Allí se cuantificó el reclutamiento coralino en sustrato artificial, usando placas de terracota de 15x15 cm, a tres profundidades (4-6, 12-14, 22-24 m), con recambio cada dos meses durante un año. Así mismo, se recolectó el sedimento depositado en la superficie de las placas en cada muestreo. Se registraron 30 reclutas en total (1 a 6 reclutas por muestreo), encontrando diferencias entre la densidad de reclutas a través del tiempo, siendo mayor entre junio-agosto, coincidiendo con reducción en la cantidad de sedimento. No hubo diferencias en la densidad de reclutas por profundidad. La cantidad de sedimento presentó diferencias en el tiempo y con la profundidad. Solo en la zona profunda del arrecife se encontró una correlación inversa (r2= -0,34, p=0,04, n=36) entre la densidad de reclutas y la cantidad de sedimento, indicando que a mayor carga de sedimento menor densidad de reclutas. El reclutamiento coralino registrado fue menor, en comparación con otros arrecifes evaluados en el Caribe, lo cual sugiere su vulnerabilidad a la alta sedimentación proveniente del río Sinú, particularmente de limos+arcillas entre febrero-abril-junio. No obstante, el reclutamiento registrado sugiere que, especies adultas dominantes y sobrevivientes en el arrecife, como A. tenuifolia, P. astreoides, P. porites y S. siderea, mantienen su actividad reproductiva.
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