El efecto de la poda de Acropora palmata como estrategia para la obtención de tejido vivo en acciones de restauración arrecifal

Introducción: Los arrecifes de coral son ecosistemas altamente degradados, por lo que ha sido necesario implementar acciones de restauración activa para recuperar su estructura y funcionamiento. Se ha implementado la propagación clonal para obtener fragmentos pequeños (~ 10 cm) de las ramas distales de colonias donadoras de corales de la especie Acropora palmata, para posteriormente fijarlos en el sustrato arrecifal, simulando el efecto de dispersión que ocurre de manera natural en esta especie, a lo que en este trabajo se denomina ''dispersión asistida". Sin embargo, es necesario evaluar los efectos de esta técnica como son: la cantidad de fragmentos que se puede obtener de cada colonia, el periodo de recuperación de tejido de las colonias donadoras y los fragmentos sembrados. Objetivo: Evaluar el efecto de poda en las colonias donadoras estimando el porcentaje de tejido podado de colonias donadoras de A. palmata y su tasa de recuperación 30 meses después. Métodos: Se realizaron cuatro monitoreos: antes, inmediatamente después de la poda, un mes después de la siembra, y 30 meses después, en cuatro colonias de A. palmata localizadas en el Parque Nacional Costa Occidental de Isla Mujeres, Punta Cancún y Punta Nizuc en el Caribe mexicano. La modelación 3D basada en fotogrametría se realizó con el software Agisoft Metashape Pro, mientras que las métricas de área de superficie de tejido, extensión radial y apical se obtuvieron mediante el software CloudCompare. Resultados: Posterior a la colecta de fragmentos de las colonias, se observó que el material utilizado en la dispersión asistida representa menos del 12% del tejido vivo. Después de un mes, las colonias donadoras presentaban una recuperación del 5% con tejido nuevo recubriendo las áreas de corte. Las colonias donadoras perdieron, en promedio, 65% de tejido vivo tras el impacto de cuatro huracanes, y en un caso la colonia fue totalmente eliminada, pero con los fragmentos sembrados se pudo conservar el genotipo. Conclusiones: La dispersión asistida podría incrementar el tejido vivo de corales ramificados en intervalos de tiempo relativamente cortos, sin comprometer la integridad de la colonia donadora, si se poda menos del 12%.

Introduction: Coral reefs are highly degraded ecosystems, for which it has been necessary to implement active restoration actions to recover their structure and functioning. Asexual propagation has been implemented to obtain small fragments (~10 cm) from the distal branches of donor colonies of corals of the species Acropora palmata, to subsequently relocate them in the reef substrate, simulating the dispersion effect that occurs naturally in the species, which in this work is called assisted propagation. However, it is necessary to evaluate the effects of this technique, such as the number of fragments that can be obtained from each colony, the tissue recovery period of the donor colonies and fragments. Objective: To address the effect of pruning on donor colonies by estimating the percentage of live tissue removed from donor colonies of A. palmata and their recovery rate after 30-months. Methods: Four surveys were carried out: before, immediately after pruning, one month after outplanting, and 30 months after pruning on four colonies of A. palmata located in the Parque Nacional Costa Occidental de Isla Mujeres, Punta Cancún and Punta Nizuc in the Mexican Caribbean. Photogrammetry-based 3D modeling was performed using Agisoft Metashape Pro software, while tissue surface area, radial and apical growth were obtained using CloudCompare software. Results: After fragment collection, the material used in the assisted propagation represents less than 12% of the living tissue. After one month, the donor colonies showed a recovery of 5%, with new tissue covering the cut areas. The donor colonies lost on average 65 % of living tissue after four hurricanes, and in one case the colony was lost all together, but with the outplanted fragments the genotype could be preserved. Conclusions: Assisted propagation could increase living tissue of branching corals in relatively short intervals of time, without serious damage to the donor colony if less than 12 % is removed.

Legacy effects of anthropogenic disturbances modulate dynamics in the world's coral reefs.

Rapidly changing conditions alter disturbance patterns, highlighting the need to better understand how the transition from pulse disturbances to more persistent stress will impact ecosystem dynamics. We conducted a global analysis of the impacts of 11 types of disturbances on reef integrity using the rate of change of coral cover as a measure of damage. Then, we evaluated how the magnitude of the damage due to thermal stress, cyclones, and diseases varied among tropical Atlantic and Indo-Pacific reefs and whether the cumulative impact of thermal stress and cyclones was able to modulate the responses of reefs to future events. We found that reef damage largely depends on the condition of a reef before a disturbance, disturbance intensity, and biogeographic region, regardless of the type of disturbance. Changes in coral cover after thermal stress events were largely influenced by the cumulative stress of past disturbances and did not depend on disturbance intensity or initial coral cover, which suggests that an ecological memory is present within coral communities. In contrast, the effect of cyclones (and likely other physical impacts) was primarily modulated by the initial reef condition and did not appear to be influenced by previous impacts. Our findings also underscore that coral reefs can recover if stressful conditions decrease, yet the lack of action to reduce anthropogenic impacts and greenhouse gas emissions continues to trigger reef degradation. We uphold that evidence-based strategies can guide managers to make better decisions to prepare for future disturbances.

Dataset of coral reefs monitoring, Puerto Morelos, Mexico, 2019.

Noticeable within the Mexican Caribbean is the Arrecife de Puerto Morelos National Park (APMNP), a marine protected area established as an essential component for managing and protecting coral reefs. In June 2019, we conducted a survey in eight shallow reef sites of the APMNP with the purpose of applying a coral reef assessment method, based on biological indicators of the condition of both benthos and fish communities. In this paper we present tables with data of biological and ecological variables such as: benthos coverage, species composition and abundance of corals, abundance of urchins and coral recruits, bleaching, coral diseases and coral mortality percent, reef relief, and composition and abundance of key commercial and herbivorous fish species. The research article related to these databases was published in the journal Diversity with the title: Puerto Morelos coral reefs, current state and their classification by a scoring system.

A meta-analysis to assess long-term spatiotemporal changes of benthic coral and macroalgae cover in the Mexican Caribbean.

Coral reefs in the wider Caribbean declined in hard coral cover by ~80% since the 1970s, but spatiotemporal analyses for sub-regions are lacking. Here, we explored benthic change patterns in the Mexican Caribbean reefs through meta-analysis between 1978 and 2016 including 125 coral reef sites. Findings revealed that hard coral cover decreased from ~26% in the 1970s to 16% in 2016, whereas macroalgae cover increased to ~30% in 2016. Both groups showed high spatiotemporal variability. Hard coral cover declined in total by 12% from 1978 to 2004 but increased again by 5% between 2005 and 2016 indicating some coral recovery after the 2005 mass bleaching event and hurricane impacts. In 2016, more than 80% of studied reefs were dominated by macroalgae, while only 15% were dominated by hard corals. This stands in contrast to 1978 when all reef sites surveyed were dominated by hard corals. This study is among the first within the Caribbean region that reports local recovery in coral cover in the Caribbean, while other Caribbean reefs have failed to recover. Most Mexican Caribbean coral reefs are now no longer dominated by hard corals. In order to prevent further reef degradation, viable and reliable conservation alternatives are required.

A rapid spread of the stony coral tissue loss disease outbreak in the Mexican Caribbean.

Caribbean reef corals have experienced unprecedented declines from climate change, anthropogenic stressors and infectious diseases in recent decades. Since 2014, a highly lethal, new disease, called stony coral tissue loss disease, has impacted many reef-coral species in Florida. During the summer of 2018, we noticed an anomalously high disease prevalence affecting different coral species in the northern portion of the Mexican Caribbean. We assessed the severity of this outbreak in 2018/2019 using the AGRRA coral protocol to survey 82 reef sites across the Mexican Caribbean. Then, using a subset of 14 sites, we detailed information from before the outbreak (2016/2017) to explore the consequences of the disease on the condition and composition of coral communities. Our findings show that the disease outbreak has already spread across the entire region by affecting similar species (with similar disease patterns) to those previously described for Florida. However, we observed a great variability in prevalence and tissue mortality that was not attributable to any geographical gradient. Using long-term data, we determined that there is no evidence of such high coral disease prevalence anywhere in the region before 2018, which suggests that the entire Mexican Caribbean was afflicted by the disease within a few months. The analysis of sites that contained pre-outbreak information showed that this event considerably increased coral mortality and severely changed the structure of coral communities in the region. Given the high prevalence and lethality of this disease, and the high number of susceptible species, we encourage reef researchers, managers and stakeholders across the Western Atlantic to accord it the highest priority for the near future.