Marco A. Liñán-Cabello

Physiological responses to oxidative stress associated with pH variations in host tissue and zooxanthellae of hermatypic coral Pocillopora capitata

To study the adaptive mechanisms of host and symbiont in a decrease in pH, coral branches of Pocillopora capitata from La Boquita reef in the Bay of Santiago, México were assigned to experimental units (n = 38 per treatment) and three pH treatments were evaluated: (a) pH 8.00–8.40 (control; Treatment C1), (b) pH 7.85–7.95 (Treatment C2) and (c) pH 7.60–7.70 (Treatment C3). Corals were collected at the beginning of the experiment (T0) and at different times: T1 (5 h), T2 (12 h), T3 (48 h) and T4 (168 h). We examined malondialdehyde (MDA), antioxidant enzyme activities (SOD and CAT), antioxidant capacity and chlorophyll a (Chl a) content. The results showed a different response to the treatment between zooxanthellae and Cnidaria tissues. Initially in zooxanthellae, we observed a SOD response for the C3 treatment; however this response did not prevent lipid degradation. In Cnidaria, the C3 resulted in a greater SOD activity from the middle to the end of the experiment. The results improve our understanding of the effects of ocean acidification, the ability of coral to respond to environmental changes and the use of biochemical indicators related to the physiological condition for the recognition of coral communities affected by a decreases in pH.

Acclimation in Pocillopora spp. during a coral restoration program in Carrizales Bay, Colima, Mexico

Fragments of the coral Pocillopora spp. were collected from Carrizales Reef to assess two transplantation techniques for coral reef restoration: (1) coral clusters (CC) technique, in which five to seven coral fragments were joined using plastic straps, and (2) simple aggregation (SA) technique, in which fragments were placed evenly on the seabed. Over 270 days, the transplanted fragments were monitored for various indicators of coral health, including skeletal growth, the proportion of colonizing invertebrates, coral fragmentation, the proportion of algal growth, signs of coral disease, and the degree of fusion of coral fragments. We found 95.5% and 89.0% survival of fragments with the CC and SA techniques, respectively. These results indicate that the CC technique leads to greater stability, merger and integration of fragments, and greater aggregation of the fragments with the substrate at transplantation sites. Both transplantation methods are economical and could easily be applied at a broad scale for coral reef restoration.

Response to pH stress in the reef-building coral Pocillopora capitata (Anthozoa: Scleractinia)

Para evaluar la respuesta metabolica del coral simbiotico Pocillopora capitata a la reduccion del pH del agua de mar en un sistema in vitro, 112 ramas de P. capitata se obtuvieron de la comunidad de corales La Boquita (LB) sin exhibir algun dano aparente de blanqueamiento. Se evaluaron 2 tratamientos de pH: a) 7,85/7,95 pH (Tratamiento C1), b) 7,60/7,70 (Tratamiento C2 ) y 8,00/8,40 pH tratamiento de control (CC). Las ramas de coral fueron asignadas aleatoriamente a unidades experimentales (n= 38 por tratamiento). Las muestras fueron tomadas en 2 tiempos para el analisis bioquimico y para evaluar cualitativamente los aspectos microestructurales por microscopia electronica de barrido: tiempo inicial, muestra tomada en 12 h (T1); tiempo final, muestras del ultimo dia de la exposicion (Tf, dia 7 del experimento). A diferencia del tejido simbionte, el analisis bioquimico del tejido del coral revelo que P. capitata muestra una respuesta inmediata reflejada en los coeficientes de ARN/ADN y proteina/ADN, asi como en las concentraciones de ARN y proteina, particularmente en el tratamiento de C2 en las horas iniciales del experimento. El analisis microestructural cualitativo identifico principalmente efectos en el tratamiento C2, que fue influenciado por la presencia de disgregaciones micro-superficiales en las regiones terminales de las fibras esqueleticas.

Recreational Beaches as Factors of Involvement in a Coral Community: Colima Case Study

Despite the great ecological importance of coral reefs, they are under threat due to both natural and anthropogenic causes. When communities are located close to the coast, intensified human activity including pollution, overfishing, indiscriminate extraction, and deforestation of associated terrestrial ecosystems can destabilize a coral ecosystem, resulting in loss of coral cover. This research analyzes different factors that can affect coral health, particularly associated with proximity to recreational beaches on the coast of Colima, Mexico. Environmental and anthropogenic factors affecting the loss of coral cover are analyzed in the La Boquita, as the main coral ecosystem of greater proximity to the beaches of great tourist load in Manzanillo. We also characterize some of the signs of stress response demonstrated by the Pocillopora genus, which is the most dominant in the region. We analyze various factors directly or indirectly related to tourists from nearby beaches, and the ways in which these factors can interact with other elements of stress, thereby helping to promote stress and affecting adaptive and reproductive capacity of the coral community. The communities of La Boquita and Carrizales are subject to different stressful conditions, and this is reflected in most indicators of reef health. La Boquita community shows signs of greater effects arising from excessive tourism and overfishing that have contributed to loss of coral coverage. Part of the current problem is caused by an influx of visitors from the beach of the same name. Negative effects stemming from lack of knowledge and awareness on the part of visitors and service providers are compounded by authorities’ insufficient efforts to carry out sustained and efficient surveillance, control, and use of these reefs.

Insights into the Feeding Habits of False Killer Whales (Pseudorca crassidens) in the Mexican Central Pacific

The false killer whale (Pseudorca crassidens) is a widely distributed odontocete, and some aspects of its basic biology, such as feeding patterns at different time scales, are not well known. Stable isotope values (δN and δC) from the skin of ten false killer whales belonging to two distinct groups (A and B) sampled in October 2012 in the Mexican Central Pacific (MCP) were analyzed. Isotopic analyses were also run on muscle tissue from ten potential fish and squid prey species, some of which were extracted from billfish stomachs. Isotopic results for false killer whales showed mean values of 16.3‰ (Group A) and 17.0‰ (Group B) for δN, and -14.8‰ for δC (both Groups A and B). Fish and squid isotopic values showed a trophic discrimination factor in relation to those of false killer whales of +3.3 to 4.0‰ for δN and +2.9‰ for δC. This suggests that these whales probably fed within the study area on these prey species or on other species with similar isotopic values. Through photographic data, we identified individuals of Group B in the same area 2 mo later (December 2012) when they were observed feeding on fishes. One false killer whale from Group A had a fragment of billfish beak embedded in its body, indicating an interaction between these two species. Results suggest that false killer whales may share the same type of food resource with billfish species such as the sailfish, an abundant species in the MCP area.

Factores asociados a la respuesta de Pocillopora spp. (Anthozoa: Scleractinia) durante un proceso de restauración en la costa del Pacífico mexicano

espanolDurante un proceso de restauracion de Pocillopora spp., usando corales de oportunidad (CO), fueron evaluados diversos atributos bioticos en dos sitios a lo largo de un ano, de manera bimensual fueron determinadas las concentraciones de aminoacidos tipo micosporina (AAMs) y niveles de clorofila a (Cl a). De manera especifica, en el ultimo muestreo se realizo un analisis de malonaldehido (MDA) y se calcularon las relaciones ARN/ADN y proteina/ADN como indicadores de estres oxidativo y actividad trascripcional en simbionte y cnidario de todos los morfotipos. En sitio Carrizales (SC) la tecnica de restauracion de ramilletes coralinos (RC) promovio la integracion de COs registrando signos de recuperacion y altas tasas de supervivencia (90%); no obstante, en el Sitio Juluapan (SJ), se observo una falta de respuesta a los indicadores bioticos y moleculares asociados a la recuperacion. Por lo tanto, los CO provenientes de Carrizales no fueron capaces de aclimatarse a un sitio en el que imperan distintas condiciones ambientales. Altas concentraciones de Cl a, AAMs, y una alta relacion ARN/ADN fueron caracteristicas de una condicion saludable de corales, que a su vez, estuvieron asociados a los indicadores de restauracion y mejor supervivencia observada. EnglishDuring a restoration process of Pocillopora spp., using opportunity corals (CO) several biotic attributes were assessed at two sites bi-monthly over a year and concentrations of mycosporin type amino acids (MAAs) and levels of chlorophyll a (Chl a) were determined. Specifically, in the last sampling analysis it was performed an analysis of malonaldehyde (MDA) and the RNA/DNA and protein/DNA relationships were calculated, as an index of oxidative stress and transcriptional activity in symbiont and coral tissue of all morphotypes. At Carrizales site (SC) the coral clusters (RC) used as a method of restoration, promoted the integration of CO showing signs of recovery and high survival rates (90%); however, in Juluapan site (SJ), a lack of response to biotic and molecular indicators associated with recovery was observed. Therefore, CO from Carrizales were not able to acclimate to a place where different conditions prevail. High concentrations of Chl a, AAMs and a high RNA/DNA ratio were characteristic of a healthy condition of coral which in turn, were associated with higher specimens survival and restoration.