The physiological responses of the coral Pocillopora capitata to environmental conditions common in winter and summer were studied in 2007 during February–March (winter) and June–July (summer) at La Boquita reef (Manzanillo, Colima, Mexico). Shallow and deep sampling stations were established at different distances from a small jetty built next to the Juluapan Lagoon. We analyzed superoxide radicals () and lipid peroxidants (TBARS); the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione‐S‐transferase (GST); chlorophyll a (Chl a), zooxanthellae density (ZD); and mycosporine‐like amino acids (MAAs). Our results showed that the , TBARS, CAT, GST, MAAs, and Chl a, levels were significantly higher in summer (P < 0.05); no seasonal difference was found for GPx, GR or ZD. We found significant differences (P < 0.05) in winter only for Chl a and ZD at shallow sites and, in contrast, for at deeper sites. The results of this study indicate that increasing temperature and radiation associated with seasonal changes (from winter to summer), the efficiency of the enzymes GST, CR and GPX, and the production of MAAs together form a powerful mechanism for P. capitata to offset the detrimental effects of environmental change.

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Coral reefs are impacted by a range of environmental variables that affect their growth and survival, the main factors being the high irradiance and temperature fluctuations. Specimens of Pocillopora capitata verrill 1864 were exposed to photosynthetically active radiation (PAR) and ultraviolet radiation (UvR) for 32h under laboratory conditions. We examined lipid peroxidation (MDA), antioxidant enzyme activities (SOD, CAT, GPx and GST), chlorophyll a (Chl a), carotenoid pigments (CPs), mycosporine-like amino acids (MAAs), and expulsion of zooxanthellae. Our results revealed that corals exposed to UvR had relatively low levels of carotenoids and antioxidant enzyme activities compared to those exposed to PAR, as well as lower CPs/Chl a ratios. Although MAAs and CPs are rapidly produced as non-enzymatic antioxidants in response to UvR in corals, these were not sufficient, even in the dark phase of the experiment, to mitigate the damage caused by formation of reactive oxygen species (ROS), which caused breakdown of the symbiotic relationship between the zooxanthellae and the host animal to an extent 33 times greater than in the PAR treatment. In this study, it could be possible to distinguish that, parallel to the short-term adjustments, such as the amount of pigment in the algae or the sensitivity of the photosynthetic response reported in other species of coral, P. capitata exhibits at the enzymatic level a series of responses oriented to resist the effects derived from the propagation of ROS and, thus, to adapt to and maintain its reproductive capacity in shallow oceanic environments that commonly exhibit high UvR levels. Nevertheless, as a result of the inappropriate location of the artificial intercommunication structure of the Juluapan Lagoon with respect to the arrecifal area of study and therefore of the tides influence, other variables, such as the changes in short-term in turbidity, sediment inputs, nutrients, temperature and osmolarity, can act in combination and cause irreversible damage. The implementation of a management plan for the coralline reefs of the Mexican Pacific coast is required.

ABSTRACT. The response of zooplankton, phytoplankton biomass (Chl-a concentration) and nutrients to the oceanographic variability in the Mexican Central Pacific was studied over three oceanographic surveys realized in 2010 (January, May and October). The highest zooplankton biomass (48 mL 1000 m -3 ) was registered in May when nitrites, nitrates, phosphates and silicates were also highest and mean Chl-a was 0.67 mg m -3. The lowest zooplankton biomass was registered in October, with a mean value of 25 mL 1000 m -3. Twenty-nine taxonomic groups of zooplankton were recorded, of which copepods contributed 71% of total abundance followed by chaetognaths (6%) and euphausiids (5%). Multivariate BEST test demonstrated that mixed layer depth and temperature at 25 m depth can explain the distribution of major zooplankton groups. The study area was influenced by El Niño conditions, which caused a seasonal shift. Coastal upwelling was evident until late summer, when geostrophic analysis showed a predominant SW component near the Jalisco coast. We suggest a possible top-down control of zooplankton grazing over phytoplankton, and acclimatization of both plankton groups to variability in environmental conditions induced by the transition from warm to cold ENSO phase.

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Th e study focuses on the environmental problem of diff use pollution from agriculture (DPA) as a result of the land use and the policy intervention that can be used to mitigate the problem. Attention is paid to the use of economic instruments (EIs) in policies concerning the DPA. Also, policy options, the advantages and disadvantages of the EIs and their assessment are looked at.

In the present study the abundance of epiphytic dinoflagellates was evaluated at two coral reef sites of the natural protected areas, Arrecife de Puerto Morelos and Isla Contoy, located in the northern Mesoamerican Reef System of the Mexican Caribbean. Abundances were monitored from April to December, 2015 on two genera of macroalga belonging to different functional groups: Dictyota and Amphiroa. In general, the total abundance of dinoflagellates was higher in Puerto Morelos on both macroalgae. Ostreopsis cf. marina and O. heptagona were the dominant species. Relative abundance of these species varied from 8 to 99% of total epiphytic dinoflagellates. Maximum abundances at Puerto Morelos were registered in April, with 33,801 cells•g −1 on Dictyota and 6,264 cells•g −1 on Amphiroa. In Isla Contoy the maximum abundance was 16,006 cells•g −1 and it was detected on Dictyota during December. Other dinoflagellate genera were more abundant during the warmer period (May-September) in both locations. Prorocentrum was the second most abundant genus and was represented by six species (P. hoffmannianum, P. lima, P. belizeanum, P. elegans, P. emarginatum, and P. rathymum). The maximum pooled abundance of Prorocentrum species was 4,144 cells•g −1 on Dictyota in August. Coolia spp. did not reach abundances higher than 1,000 cells•g −1 and Gambierdiscus spp. only exceeded 100 cells•g −1 during August. Mean water temperature in Isla Contoy was significantly lower than that of Puerto Morelos during the entire study period. There was a negative correlation between the water temperature and the abundance of O. cf. marina. The dominance of Ostreopsis in the Caribbean is significant because of its capability to produce palytoxin analogs and its potential role in ciguatera fish poisoning outbreaks in the region. This is the first study that reports blooms of Ostreopsis in Mexican Caribbean coral reefs, a fact that emphasizes the significance of this genus at global scale.

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