Seasonal tendencies of microplastics around coral reefs in selected Marine Protected National Parks of Gulf of California, Mexico.

This study focuses on the presence of MPs in the sediment beds around coral reefs of MPNPs in Baja California Sur, México. Based on seasonal sampling results, comparison of MPs from Cabo Pulmo (avg. 680.25 items/100 g-1 d.w) recorded higher values than Espiritu Santo Island (avg. 321.75 items/100 g-1 d.w) from backshore/foreshore regions. Fibrous MPs are the dominant morphotypes followed by fragments and spheres. SEM/EDS analysis revealed that the MPs are altered texturally in surface and is bioavailable to marine organisms independent of size/shape. FTIR analysis indicate different polymers (in %) in the form of PP (70), PET (65), HDPE (59), LDPE (50), PS (30), PC (18), PU (10) and RYN (10). Most of the MPs are secondary in origin resulting from man-made and tourist's activities controlled by wave transportation and tidal currents. Existence of MPs in sediment beds around the coral reefs signals the ways for future investigations.

History of perspectives on the study of coral disease in the eastern tropical Pacific.

Disease in coral species is one factor associated with the current degradation process of tropical reefs. The history of research on coral pathologies dates to 1970 with the first reports of diseases in the Greater Caribbean and Indo-Pacific regions, although some anecdotal observations were made earlier. Today, there is information on the health conditions of >200 coral species in 70 countries. The special natural conditions under which reefs develop in the eastern tropical Pacific (ETP) and the predominance of a single coral genus, Pocillopora (a host highly susceptible to disease), leave them vulnerable to health impairments and the loss of viability, structure and function in the wider ecosystem. Therefore, coral reefs in the ETP are ideal systems for studies of biodiversity and survivorship. To clarify the status of knowledge on coral diseases in the ETP, we reviewed scientific studies conducted there from 1970-2018, comparing 127 publications to literature on other reef regions in the Pacific. Despite the vulnerability of reefs in the ETP, only limited information exists describing and investigating the etiology of lesions and other signs of health deterioration in corals, and there are few baseline studies of coral reefs or analyses of the spatial and temporal dynamics of disease syndromes. In general, efforts to study coral diseases in the ETP are inadequate.

Evidence of sexual dimorphism in skeletal morphology of a gonochoric reef coral.

In the emerald coral Porites panamensis, the rates of elongation and calcification of colonies are higher in males than in females, probably because of the higher energetic demands of the latter in order to cope with the development of the large planulae produced throughout the year. This differing energetic demand could also be reflected in the sexual dimorphism of the calyces; hence, to test this hypothesis, 11 morphological traits of the corallite were assessed from 63 colonies that were collected in the southern Gulf of California, Mexico. Three traits showed statistical differences between sexes, enabling accurate distinction of males from females. Our results confirm for the first time the existence of external sexual dimorphism in a reef-building coral, opening the possibility that sex-related morphological differences may occur generally in gonochoric scleractinians. These findings can be very useful for the correct classification and characterization of recent and fossil records, helping to improve the historical and evolutive understanding of reef-building corals facing threats under environmental changes.

Estructura de las asociaciones de las estrellas de mar (Asteroidea) en arrecifes rocosos del Golfo de California, México / Sea star (Asteroidea) association structures on the rocky reef in the Gulf of California, Mexico

Sea stars are invertebrates that play relevant roles in rocky and coral reefs: they occupy different levels in food webs and may act as top predators. There are numerous studies on taxonomy and biogeography of the class in the eastern tropical Pacific, but information about the attributes and composition of its assemblages is scant. The objectives of this study were the examination and comparison of asteroid community structure from four regions of the Gulf of California, Mexico, characterized by the presence of rocky reefs, and the search for possible associations between pairs of species. In August 2004 we visited four locations in the western gulf: Bahia de Los Angeles (29 degrees N), Santa Rosalia (27 degrees N), Loreto (26 degrees N) and La Paz (24 degrees N), and censuses sea stars using 50 m2 belt transects (N=93). Abundance and species richness was estimated, as well as diversity (H'), evenness (J') and taxonomic distinctness (delta*); then, all variables were compared among regions with analysis of variance. In addition, an ordination analysis was run looking for groups of locations with similar faunistic composition. Our results showed that Loreto Bay had the highest richness and abundance of asteroids, probably because it presents a large number of habitats and multiple food sources; these conditions seem to favor the occurrence of rare species and of detritivores. However, there were no significant interregional differences among ecological indices, nor we detected groups of locations singled out because of its species composition. Thus, community structure of sea stars in rocky areas of the Gulf of California is quite homogeneous and do not change with latitude. This is a consequence of the fact that all regions under analysis had the species Phataria unifascialis and Pharia pyramidatus as dominant in number. There were significant positive associations between three pairs of species: apparently competition is not particularly relevant to control sea star community structure in the Gulf.

Oceanographic conditions and diversity of sea stars (Echinodermata: Asteroidea) in the Gulf of California, México

Species richness is one of the best indicators of biodiversity. However, there are few investigations on concordance of diversity patterns and environmental settings for marine regions. The objectives of this study were to correlate species richness of shallow water (< 200 m deep) sea stars with key oceanographic factors in the Gulf of California, México, and to predict species richness of Asteroidea using multiple regressions. In these analyses the Gulf was divided into nine sections of one degree in latitude (from 23-31 degrees N), at each section we recorded: continental shelf area (at 100 and 200 m depth), temperature mean and range at three depth levels (0, 60 and 120 m), thermocline depth, surface nutrient concentrations (nitrates, phosphates and silicates), surface photosynthetic pigment concentration, and integrated productivity. Sea star species richness at each latitudinal section was estimated from literature data, new collections and museum records. Species were assigned to one of the following feeding guilds: predators of small mobile invertebrates (I), detritivores (D), predators of colonial organisms (C), generalist carnivores (G), and planktivores (P). There are 47 shallow water asteroid species in the Gulf of California (16 I, 15 D, eight C, six G, one P and one not assigned). Total species richness and guild species richness showed strong latitudinal attenuation patterns and were higher in the southernmost Gulf, an area characterized by a narrow shelf, high temperature, and low nutrient concentrations. Species diversity for each guild was correlated to a set of oceanographic parameters: temperature, nitrate concentration, and integrated productivity were linked to richness in must cases. We detected that nutrients and surface pigments always presented negative relationships with species richness, indicating that productive environments limit asteroid diversity in the study area. Finally, the postulated regression models to estimate species richness from oceanographic data were significant and highly precise. We conclude that species richness of Asteroidea in the Gulf of California is related to oceanographic conditions and can be estimated from regional oceanographic information

Different algal symbionts explain the vertical distribution of dominant reef corals in the eastern Pacific.

Symbiotic reef corals occupy the entire photic zone; however, most species have distinct zonation patterns within the light intensity gradient. It is hypothesized that the presence of specific symbionts adapted to different light regimes may determine the vertical distribution of particular hosts. We have tested this hypothesis by genetic and in situ physiological analyses of the algal populations occupying two dominant eastern Pacific corals, over their vertical distribution in the Gulf of California. Our findings indicate that each coral species hosts a distinct algal taxon adapted to a particular light regime. The differential use of light by specific symbiotic dinoflagellates constitutes an important axis for niche diversification and is sufficient to explain the vertical distribution patterns of these two coral species.

[Taxonomy and distribution of the hermatypic corals (Scleractinia) of the Revillagigedo Archipelago, Mexico]. / Taxonomía y distribución de los corales hermatípicos (Scleractinia) del Archipiélago de Revillagigedo, México.

In spite of some recent detailed accounts about the scleractinian corals of the Archipiélago de Revillagigedo, taxonomic work on this fauna has been sparse. Consequently, solid taxonomic background is needed, especially to support further studies at community level. During five field trips (between 1990 and 1995) collections were made at different depths on three of the archipelago islands: Socorro, Clarión and San Benedicto. A total of 250 specimens were collected. Coral identifications were made using co-occurrence methods concomitant with their descriptions, diagnosis and illustrations from a number of publications, and with morphological analysis. Coral distributions were taken from literature. Twenty-two species of zooxanthellate scleractinian corals are described, with their local and world-wide geographic distribution, and each illustrated with macro and microphotographs. Keys to the genera and species of the archipelago are also included. Porites and Pocillopora exhibit the highest species richness with a great intraspecific variation, as well as a number of morphological convergences within and between species which form species complexes, and several new species and morphs. Clarion, the oldest and most isolated island of the archipelago, harbors a number of coral morphs that are probable new species. More than half of the species found at the Revillagigedos are distributed exclusively on oceanic islands of the eastern Pacific and close to one third exist only at this archipelago. The Revillagigedos have strong faunal similarities and share a number of endemics with Clipperton Atoll, all of which support the idea that these islands constitute a separate biogeographic subregion within the eastern Pacific. Lastly, the present document substantiates the hypothesis that the Revillagigedos are important stepping-stone islands for the migration of in-shore marine species from the Central to the eastern Pacific.

[Fishes of the Cabo Pulmo reef, Gulf of California, Mexico: systematic list and aspects of abundance and biogeography]. / Los peces del arrecife de Cabo Pulmo, Golfo de California, México: lista sistemática y aspectos de abundancia y biogeografía.

The Cabo Pulmo reef is the most important coral formation of the Gulf of California; however, its ichthyological fauna has been poorly studied. To produce a systematic list with data on relative abundance and frequency, and biogeographical affinities, we relied on visual census, field observations, analysis of commercial and sport fisheries (from 1986 to 1998), and the literature. A total of 236 species have been recorded at Cabo Pulmo (155 genera and 60 families). This number doubles previous compilations and represents 65.1% of all reef fishes known from the Gulf of California, and about 35% of its entire shallow-water fishes. Of the total species number, 68.3% are from the Panamic Province, 11.0% Indo Pacific colonizers and the same percentage gulf endemics, 7.6% are circumtropical, 1.7% Atlantic and 0.5% cosmopolitan; none are endemic to the reef. The most abundant taxa are the labrids Thalassoma lucasanum, T. grammaticum and the pomacentrid Chromis atrilobata. Only eleven species (4.7% of total) appeared in 75% to 100% of census, and 36 (15.3% of total) had high levels of both abundance and frequency, evidencing that the community is dominated by few taxa. Local species richness exceeds the number reported for most rocky or coral reefs of the Pacific coast of México, and indicates that Cabo Pulmo is a key area in the gulf and the entire Mexican Pacific, from the ichthyological point of view.