Penshell Atrina oldroydii (Bivalvia: Pinnidae) in the Gulf of California

The genus Atrina is a cosmopolitan bivalve mollusk, but the distribution of the different species is probably dependent on ecological characteristics, such as specific habitats.The northern limit of the geographic distribution of the penshell Atrina (S.) oldroydii Dall, 1901 is the Panamic Province in Bahía Magdalena, Baja California Sur, even though it is from San Pedro, California. In this work, we report a new penshell bank of A. oldroydii on muddy substrate at 30-m depth, about 29-km, from Bahía de Kino, Sonora Mexico, at 3 to 14 organisms per m2 with maximum length of 319 mm. We concluded that the species encompasses a new record, not previously reported to the inner waters of the Gulf of California

Caracterización Ecológica Cuantitativa De La Vegetación En Sitios De La Costa Central Del Golfo En El Desierto Sonorense

The Central Gulf Coast, subdivision of the Sonoran Desert, requires urgent actions to ecological restoration and development of sustainable alternatives to promote the generation of economic benefits in a manner consistent with the conservation of natural resources. Four sites were selected in the coastal region of the municipality of Hermosillo between 28°42'04" and 28°52'24" North and 111°45'39" and 111°56'48" West. Sites are representative of the various plant associations with variants in soil structure, topography and intensities of use. General plant diversity, plant density, height and canopy cover from shrub/tree plants, and basal cover from herbaceous plants were evaluated at each site. Species richness indices, equity and diversity among plant communities were compared. Major plant associations were identified as 1) Sarcocaulescent scrub, 2) Halophytes Communities, 3) Arbo-crasicaulescent scrub, and 4) Arbo-suffrutescent scrub. Sixty five plant species in 26 families were identified. Families with higher number of species were Cactaceae (12), Euphorbiaceae (7), Fabaceae (7) and Malvaceae (5). Species richness and diversity indices indicated differences between sites. Values of relative importance are identified among plant associations for subsequent analysis of productive and ecological trends as well as for the assessment of wildlife diversity and population parameters associated to each condition of the vegetation. This work is aimed to generate integral models for identifying feasibility and setting priorities for ecological restoration practices in the Sonoran Desert

Ecological and Physiological Studies of Gymnodinium catenatum in the Mexican Pacific: A Review

This review presents a detailed analysis of the state of knowledge of studies done in Mexico related to the dinoflagellate Gymnodinium catenatum, a paralytic toxin producer. This species was first reported in the Gulf of California in 1939; since then most studies in Mexico have focused on local blooms and seasonal variations. G. catenatum is most abundant during March and April, usually associated with water temperatures between 18 and 25 ºC and an increase in nutrients. In vitro studies of G. catenatum strains from different bays along the Pacific coast of Mexico show that this species can grow in wide ranges of salinities, temperatures, and N:P ratios. Latitudinal differences are observed in the toxicity and toxin profile, but the presence of dcSTX, dcGTX2-3, C1, and C2 are usual components. A common characteristic of the toxin profile found in shellfish, when G. catenatum is present in the coastal environment, is the detection of dcGTX2-3, dcSTX, C1, and C2. Few bioassay studies have reported effects in mollusks and lethal effects in mice, and shrimp; however no adverse effects have been observed in the copepod Acartia clausi. Interestingly, genetic sequencing of D1-D2 LSU rDNA revealed that it differs only in one base pair, compared with strains from other regions

Distribution and abundance of postlarvae and juveniles of shrimps of the genus Penaeus in Kino Bay and La Cruz lagoon, Sonora, Mexico

Samplings with plankton net, cast net and otter trawl were made every two weeks to estimate the distribution and abundance of Penaeus shrimp postlarvae and juveniles in Kino Bay (IX/89-IX/90) and La Cruz coastal lagoon (VII/89-IV/91), Sonora, Mexico. The postlarvae were present from June to November, with maximum average abundance in July 1990: 220.58 postlarvae/10 m3 in La Cruz and 72.5 postlarvae/10 m3 in Kino Bay. Penaeus califoniensis was the most dominant species. There was no statistical evidence of postlarva aggregation at the sampling stations. Only juveniles of P. califoniensis (brown shrimp) and P. stylirostris (blue shrimp) were caught, dominating the first. The maximum total length of juveniles was 13 cm (brown shrimp) and 16 cm (blue shrimp). From length data, we believe that brown shrimp enter La Cruz at an earlier developmental stage than blue shrimp

Comparative growth, condition, and survival of juvenile Crassostrea gigas and C. corteziensis oysters cultivated in summer and winter

We report differences in growth, condition, and survival of the Pacific oyster Crassostrea gigas and the Cortez oyster C. corteziensis cultivated in a semi-arid lagoon in northwestern Mexico (Las Guásimas, Sonora) during summer and winter, periods corresponding to juvenile development at the production sites. Three sampling stations were established to determine variations in temperature, salinity, seston, chlorophyll a content, oxygen concentration, and pH at the coastal system. Growth rates and condition indices were higher during winter and cumulative mortality was higher in summer. This was the pattern for both species though significant differences were noted only for C. gigas. The Pacific oyster showed faster growth in winter and slower in summer than the Cortez oyster. While food availability was not a limiting factor in any season, differences in growth, condition, and survival were related to temperature, which ranged from a maximum of 32.7°C in summer to a minimum of 12.7°C in winter. Low temperatures are propitious for C. gigas, since high temperatures cause physiological stress. The Cortez oyster has the ability to adapt its metabolic functions to variations in temperature with no differences in growth and condition during the extreme seasons. The Pacific oyster exhibited better adaptation to variations in conditions at sites like Las Guásimas, but high temperature is a limiting factor for cultivation. Autumn is a propitious period to begin cultivating C. gigas, while the native C. corteziensis can be cultivated year-round.