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Global warming and ocean acidification affect coral calcification. Nevertheless, there is not enough information regarding the growth parameters of the main reef-building coral species in marginal growth areas such as the Pacific coast of southern Mexico. In order to fill this gap, coral growth parameters of 8 hermatypic coral species (massive species: Porites panamensis, Porites lobata, Pavona gigantea, and Pavona varians; branching species: Pocillopora meandrina, Pocillopora damicornis, Pocillopora verrucosa, and Pocillopora capitata) were estimated in 2 areas of the southern Mexican Pacific. Branching coral species had a higher calcification rate (2.99-5.23 g CaCO3 cm-2 yr-1) than massive species (0.34-1.13 g CaCO3 cm-2 yr-1). A significant relation between sea surface temperature (SST) and skeletal density was observed in all massive coral species. Also, 2 massive species (P. gigantea and P. varians) showed a significant relation between SST and calcification rate. Upwelling in the Gulf of Tehuantepec transports deep water with low pH and low aragonite saturation, and may be affecting the calcification rate of stony corals in the studied area. [ABSTRACT FROM AUTHOR]

Many crustacean species are obligate associates of pocilloporid corals, where they feed, reproduce, and find shelter. However, these coral-associated crustaceans have been poorly studied in the eastern tropical Pacific. Determining the crustacean richness and taxonomic distinctness could help in comparing different coral reefs and the potential effects of degradation. This study evaluated the spatio–temporal variation of the taxonomic diversity and distinctness of coral-associated crustaceans in four ecosystems of the Central Mexican Pacific (CMP) with different conditions and coral cover. In all ecosystems, 48 quadrants were sampled during the summer and winter for two years. A total of 12,647 individuals belonging to 88 species, 43 genera, and 21 families were recorded. The sampling effort yielded 79.6% of the expected species richness in the study area. Species rarity had 19% singletons, 4% doubletons, 22% unique, and 9% duplicate species; two species represented new records for the Mexican Pacific, and six were new to the CMP. This study recorded most of the symbiotic crustacean species in pocilloporid corals previously reported in the CMP. The taxonomic diversity and distinctness differed significantly between coral ecosystems and seasons, which was also visualized by nMDS ordination, showing an evident spatio–temporal variation in the taxonomic beta diversity. [ABSTRACT FROM AUTHOR]

The contributions of sexual versus asexual reproduction are thought to play an important role in the abundance and ecological success of corals, especially in marginal habitats. Pocillopora corals are distributed throughout the Indo-Pacific and dominate shallow hard-bottom communities in the eastern Pacific where broad seasonal fluctuations in temperature and water turbidity create suboptimal conditions for reef community development. Previous work had revealed three genetic clades in the eastern Pacific that show little correspondence with colony morphology; the broad distribution of type 1 extends into the subtropical southern Gulf of California. Here we examine genetic and clonal structure of two type 1 communities separated by 10 km with microsatellite data. Samples were collected randomly in six 10 m radius circular plots (20 colonies per plot, 3 plots per site). Sites differed in their relative clonality because clonemates (ramets) from a single clone (genet) dominated a large portion (90.9 m long) of the protected leeward side of Gaviota Island (Number of genets/Number of samples = 0.35; observed Genotypic diversity/expected Genotypic diversity = 0.087), while an exposed community at the entrance to La Paz Bay, Punta Galeras, exhibited high genotypic diversity ( N/ N = 0.85; G/ G = 0.714). Gene flow was unrestricted between sites indicating these communities comprised a single population. The relative proportion of asexual colonies found between community aggregations of Pocillopora in the Gulf of California differed significantly and suggests factors at local, not regional, scales affect these patterns. The possibility that heterogeneity in clonal structure is common throughout the eastern Pacific and across the west Indo-Pacific requires further study. Finally, since morphological variation in Pocillopora has been underappreciated and is in need of taxonomic revision, the use of a consistent field-sampling protocol and high-resolution makers will advance ecological research and aid in the conservation of these corals. [ABSTRACT FROM AUTHOR]

A mild bleaching event was observed among Pocillopora spp. in the southern Gulf of California in the spring of 2006. Uniform bleaching occurred in numerous colonies on the upper portions of their branches. Most (∼90%) colonies that exhibited bleaching contained a species of endosymbiotic dinoflagellate, Symbiodinium C1b-c, which differed from the Symbiodinium D1 found inhabiting most unbleached colonies. Analysis of chlorophyll fluorescence, indicated a decline in photosystem II photochemical activity, especially among colonies populated with C1b-c. By early August, most affected colonies had recovered their normal pigmentation and fluorescence values were once again high for all colonies. No mortality was observed among tagged bleached colonies nor did symbiont species composition change during recovery. This unusual episode of bleaching did not appear to be a response to thermal stress, but may have been triggered by high levels of solar radiation during a period of unseasonally high water clarity in the early spring. [ABSTRACT FROM AUTHOR]

The hermatypic coral ecosystems of the southern coast of Jalisco, Mexico, present an important species richness and coverage for the Mexican Central Pacific. However, knowledge of these ecosystems of the Jalisco coast is fragmented. Studies have concentrated on few localities, employing a limited number of coral health indicators, and gaps still remain in the knowledge of ecosystem structure and its local and mesoscale variation. This study evaluated spatial variations in the coral assemblage structure in six sites on the southern coast of Jalisco, Mexico, five of which had never been studied before. Sampling was conducted in September 2019, utilizing a total of 35 transects (each of 25 m in length). The cover of each coral species was recorded, as well as other benthic groups and substrate types. Different community attributes, patterns of similarity in coral species and their relationships with the benthic habitat structure were evaluated in each site. The results showed that the observed richness (8 species) represented 83.7% of that expected by chance. Significant spatial variation was found between coral patch sites and coral community sites, in terms of species richness, Shannon diversity and live coral cover, as well as in the structure of the coral assemblage and the benthic habitat. The results evidenced these conditions despite the existence of a considerable dominance of branched corals of the genus Pocillopora. The species that contributed most to the differences between coral patch sites and coral community sites were Pocillopora damicornis , Pocillopora capitata and Pocillopora verrucosa. For their part, the benthic habitat structural elements that favored the differences between site conditions were live coral cover and turf. • An analysis of coral assemblages from new sites at the Mexican Pacific is presented. • A significant coral assemblage spatial variation was found among sites. • Different coral development was found among sites. • The Pocillopora branching corals dominated in most sites. • The coral assemblage was correlated to the cover of live coral and calcareous algae. [ABSTRACT FROM AUTHOR]

Coral reefs are threatened by a variety of factors including diseases that have caused significant damage in some regions such as in the Caribbean. At present, no data are available on coral diseases in the Mexican Pacific where Pocillopora spp. is a dominant component of coral communities. Here, we describe gross and microscopic morphology of lesions found in pocilloporids at four sites in the Mexican Pacific. Corals were identified and their lesions photographed and quantified in the field. Tissue samples were collected from healthy and affected colonies for histopathology. We recorded seven species of pocilloporids at the study sites with Isla Isabel being the location with the highest coral diversity (H'=1.27). Lesions were present in 42% of the colonies and included discoloration (32%), predation-induced tissue loss (30%), unexplained tissue loss (3%) and overgrowth by sponges or algae (35%). The most affected species, P. damicornis (50%), was also one of the most common in the region. No species was more prone to a particular lesion, but there was a significant association between location and the presence of lesions. Northern Islas Marietas (61%) and Isla Isabel (41%) had the highest prevalence of lesions, followed by Manzanillo (37%) and Bahías de Huatulco (23%). Histological changes included atrophy of the surface body wall with depletion of zooxanthellae (91%) in corals with discoloration (bleaching). Ablation of tissue from mesoglea (18%) was also observed. Colonies with unexplained tissue loss showed atrophy and thinning of the epidermis (89%), characterized by cuboidal instead of pseudocolumnar cells normally found in healthy pseudocolumnar ciliated epithelium. Bacterial aggregates between the mesoglea and gastrodermis (11%) were very conspicuous in healthy and diseased corals. Lesions produced by fish bites and gastropods were associated with tissue atrophy (40%) and, in some cases, algal overgrowth near the lesion (20%). No infectious agents associated with cell pathology were detected microscopically. Bleaching and overgrowth by algae and sponges, as well as unexplained tissue loss, are common in Pocillopora. These lesions and anatomical changes warrant further study since their incidence is potentially indicative of reef degradation., (Copyright © 2014 Elsevier Inc. All rights reserved.)