Cristian Moisés Galván-Villa

Additive partitioning of reef fish diversity variation: a promising marine biodiversity management tool

Additive partitioning was applied to variation in reef fish spatial diversity at Isla Isabel National Park, Nayarit state, Mexico, and to identify the environmental and spatial variables that best explains it. Analyses included expected and observed species curves, rare species analysis, additive partitioning of alpha- and beta-diversity, and canonical redundancy analysis. A total of 10,517 individuals were recorded from 75 species and 33 reef fish families, representing 85% of expected richness. Species richness beta-diversity was dependent on the site scale, while the alpha-diversity of the Shannon diversity was most significant at the transect scale. Canonical partitioning showed species richness and Shannon diversity was explained by spatially-structured environmental components. Variation in species composition and abundance was explained by a purely environmental component. Therefore, elements of habitat structure (especially corals), topographic complexity, and refuge availability determine fish species diversity. Our results suggest that greater emphasis is required to conserve sites that promote β-diversity, increasing fish spatial diversity. In Isla Isabel, these sites would be mostly those located at eastern and southern of protected sides, where coral reef patches are well represented. The results of this multi-scale analysis are valuable and useful as an addition and complement to the holistic management strategies implemented at Isla Isabel.

Ensamblajes de peces arrecifales y su relación con el hábitat bentónico de la Isla Isabel, Nayarit, México

This study describes the reef fish assemblages of Isabel Island and their relation with the benthos heterogeneity. A total of 39 visual transects from 19 different localities were performed in the zones North, South, East, and West around the island during December 2002, October 2004, and April 2005. The species composition and their abundance were registered in each transect. Video-transects were also performed to estimate the cover of benthic morpho-functional groups. A total of 9,956 specimens of fishes belonging to 118 species, 85 genera, and 51 families were registered. The 58.3% of the species have biogeographic affinity to the Panamic province. Six endemic species of the Mexican Pacific were registered, including two species endemic to the Gulf of California. According to the biological value index seven species were dominant in the island: Thalassoma lucasanum, Prionurus punctatus, Stegastes flavilatus, Halichoeres dispilus, Acanthurus xanthopterus, Abudefduf troschelii, and Johnrandallia nigrirostris. The indexes of diversity and evenness were not significantly different between the four zones of the island. However, there was a relation between the zones with higher biodiversity (South and East) and some components of the benthic habitat. The principal component analysis found that the cover of corals and rocks are highly related with the dominant species of the island, while the zones with highest proportion of sand, sponges, and gorgonians have less influence on fish diversity.

Bivalve Molluscs from the Continental Shelf of Jalisco and Colima, Mexican Central Pacific

Abstract: A survey for bivalves was conducted at 25 sampling stations on the Mexican Central Pacific shelf off Jalisco and Colima, during the summer of 1988. The bivalves were sampled with a Van Veen grab at 16 stations with medium sand, sandy silt, and silty clay substrata at depths between 18 and 112 m. A total of 5,196 individuals belonging to 59 genera and 95 species of bivalves were found. A systematic list is provided with the relative abundance and density (individuals/m2) for each species and information on depth, type of substratum, bottom water temperature, and oxygen concentration for each station. The twelve most common species (>100 individuals/station) in descending order of abundance were: Nuculana laeviradius (Pilsbry and Lowe, 1932), Crassinella pacifica (C. B. Adams, 1852), Corbula nasuta G. B. Sowerby I, 1833, Anadara adamsi Olsson, 1961, Parvilucina approximata (Dall, 1901), Nucula declivis Hinds, 1843, Corbula ira Dall, 1908, Radiolucina cancellaris (Philippi, 1846), Cyclopecten pernomus (Hertlein, 1935), Nuculana lobula (Dall, 1908), Parvilucina mazatlanica (Carpenter, 1857), and Gouldia californica Dall, 1917. The bathymetric patterns in the abundance and species composition of the bivalve community and their relationship to environmental parameters are discussed. The structure of the assemblages differed with depth, with peak abundances and species richness (1) between 24 and 40 m with medium sand and sandy silt substrata and (2) at intermediate depths between 71 and 74 m, with sandy silt and silty clay substrata. The species characterizing shallow, intermediate, and deep zones were the most abundant or those exclusive of each zone. Diversity, dominance, and evenness decreased at the deeper stations. The distinctive species composition of these zones may be the result of variation in depth, oxygen concentration, and substratum.

Annotated checklist of marine fishes from the Sanctuary of Bahía Chamela, Mexico with occurrence and biogeographic data

Abstract An annotated checklist of marine fishes of the Sanctuary of Islands and Islets of Bahía Chamela in the central Mexican Pacific is presented. Records of fish species were obtained by different methods including visual census, sampling with anesthetics, fisherman-nets, and trawling with a biological dredge. Additional records were obtained from natural history collections and publications. The list comprises 196 species in 64 families and 141 genera. The Carangidae is the most speciose family with 11 species, followed by the Labridae with 10 and the Pomacentridae with nine. Fourteen species are endemic in Mexican Pacific waters, but none is restricted to Bahía Chamela. The most dominant species recorded during underwater surveys were Epinephelus labriformis, Stegastes flavilatus, and Halichoeres dispilus. Most species are of tropical affinities distributed throughout the tropical eastern Pacific (123), eastern Pacific (23), and Mexican Pacific (14). Other species are known from the eastern and Indo-Pacific regions (18), eastern Pacific and western Atlantic oceans (2), and some are circumtropical (9). A new record of the Gulf Brotula Ogilbia ventralis is provided for the Bahía Chamela and its geographical distribution is extended to Mexican central Pacific.

Caprella suprapiscis sp. nov. (Crustacea: Amphipoda: Caprellidae) from the Pacific coast of Mexico.

A new species of caprellid, Caprella suprapiscis sp. nov., is described based on several specimens collected from Bahía Chamela, Jalisco, Mexico. All specimens were found in association with the scorpionfish Scorpaena mystes. Caprellids are set on the dorsal surface of fishes. The species is distinguished by head with a short dorsal projection, eyes distinctive, body slender and smooth, peduncular articles of antenna 1 not setose, antenna 2 with swimming setae, gnathopod 2 with three ventral projections in males. The species is close to C. californica, C. mercedesae, and C. scaura for a sharp spine on the forehead but can be distinguished by gnathopod 2 finely setose, and basis of gnathopod 2 shorter.

Species composition, richness, and distribution of marine bivalve molluscs in Bahía de Mazatlán, México

Abstract We describe the composition and distribution of bivalve molluscs from the sandy and rocky intertidal and the shallow subtidal environments of Bahía de Mazatlán, México. The bivalve fauna of the bay is represented by 89 living species in 28 families, including 37 new records and four range extensions: Lithophaga hastasia, Adula soleniformis, Mactrellona subalata, and Strigilla ervilia. The number of species increases from the upper (44) and lower intertidal (53) to the shallow subtidal (76), but only 11 (17%) have a wide distribution in the bay (i.e., found in all sampling sites and environments). The bivalve assemblages are composed of four main life forms: 27 epifaunal species, 26 infaunal, 16 semi-infaunal, and 20 endolithic. A taxonomic distinctness analysis identified the sampling sites and environments that contribute the most to the taxonomic diversity (species to suborder categories) of the bay. The present work increased significantly (31%) to 132 species previous inventories of bivalves of Bahía de Mazatlán. These species represent 34% of the bivalve diversity of the southern Golfo de California and approximately 15% of the Eastern Tropical Pacific region.

Mating behavior and rapid concealing of nuptial coloration in males of the Fishgod Blenny Malacoctenus ebisui (Teleostei: Blenniiformes)

Courting males often face the trade-off of attracting the attention of both females and predators. Rapid color change, a relatively simple solution to this dilemma, is described for nuptial males of the Fishgod Blenny Malacoctenus ebisui (Teleostei: Blenniiformes) from direct observations at three rocky reefs in the Mexican Pacific. Nuptial males showed three dark bars on a white background that covered the anterior part of the body, and three dark bars posteriorly forming a solid dark patch along the midline. The head was black with a prominent white area on the lower portion of the iris of each eye, two white patches on the upper jaw, and one central white patch on the lower jaw. When an intensely colored male was disturbed the white patches on the eyes quickly disappeared, while the other white markings became muted apparently by rapid expansion of melanophores. This relatively simple system permits males of the Fishgod Blenny to rapidly suppress their conspicuous coloration in response to perceived threats. Mating behavior of the Fishgod Blenny observed at Bahia Chamela is similar to that reported for other labrisomid blennies, with males repeatedly nudging the side of the female and both sexes alternately performing quivering movements.

Spatial analysis of bivalve mollusks diversity in Mazatlan Bay, Mexico

Mazatlan Bay is considered the northern boundary of the region with the greatest species richness of infaunal and epifaunal bivalve mollusks in the tropical eastern Pacific. The present study aimed to quantify changes in the patterns of bivalve species diversity in Mazatlan Bay at different spatial scales and to determine which scale contributes more towards the species turnover of the total diversity in the Bay. Additive and multiplicative partitions were performed in the α, β and γ diversities of four sites and two environments (intertidal and shallow subtidal) within the Bay. A total of 19,848 individuals from 27 families and 77 species of bivalves were recorded. The effectiveness of the sampling effort was evaluated using species accumulation curves, which revealed a representation of 73% in the four sites and two environments. Rarity was characterized by 20% of the singleton and unique species, and 9% of the doubletons and duplicate species. Additive partitioning showed that the species turnover among sites and between environments contributed more to bivalve total diversity. In multiplicative partitions of the sites in both environments, the greatest species richness was found at the lower scales (α1). The sites and environments showed a clear decrease in the abundant (N1) and very abundant species (N2) from α to β1–β2 scales. The spatial variability of the different habitats of the bay is important to maintain the high species richness and high percentage of different life forms found in the Bay. The β1 and β2-diversities constitute the most important component for supporting the bivalve total diversity (γ) of Mazatlan Bay.

Description of the first larval stage of Pontonia simplex (Decapoda, Caridea, Palaemonidae) from the eastern tropical Pacific

The first stage of Pontonia simplex Holthuis, 1951 collected on the coast of Jalisco, Mexico, is described and compared with that of P. pinnophylax (Otto, 1821) and Ascidonia flavomaculata (Heller, 1864).