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

Nematodes as indicators of shrimp farm impact on an amazonian estuary (Curuçá, Pará, Brazil)

Abstract Shrimp farming reduces demand on wild fishery stocks and avoids environmental damage resulting from fishing practices, however, it has the potential to affect the water quality if not properly managed. In this study the impacts of a shrimp farm in an Amazonian estuary were evaluated, focusing on changes in nematodes regarding taxonomic composition, richness, density and diversity. Sampling was conducted in August 2004 (dry season) and January 2005 (rainy season) in the river at stations situated upstream and downstream at different distances from the main source of farm effluent discharge. Thirty-eight genera were recorded with Terschellingia dominating in the dry season and Terschellingia, Daptonema, Ptycholaimellus and Gomphionema in the rainy season. Abundances were within the range recorded in other estuaries and together with genera richness and diversity showed a strong temporal pattern with significantly higher values in the rainy season. No clear patterns of changes were observed at the stations. Some signs of organic enrichment were detected but they were not yet intense, probably a consequence of the strong local hydrodynamics and the age of the shrimp farm, which was just starting its operation. We recommend that in future studies on farming impacts a combination of factors, beyond the physical and chemical parameters of the water and sediments or taxonomic refinement, should be taken into account - such as the duration of the operation of the farm, the area occupied by ponds and the farm's production. Furthermore, we also believe that nematodes are a useful tool for evaluating aquaculture impacts due to the ease of sampling and because they are organisms at the base of marine food chain

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

Evaluation of culturable, nitrifying, ammonium-oxidizing, and metabolically active bacteria in shrimp farm effluents of Kino Bay, Sonora, México

Bacteria from shrimp farm effluents in Kino Bay, Sonora, México were evaluated during the 2008 production cycle. The culturable bacterial populations considered were viable heterotrophic bacteria (VHB) and Vibrio-like bacteria (VLB). In addition, total bacteria (TB), metabolically active bacteria (MAB), nitrifying bacteria (NB), and ammonium-oxidizing bacteria (AOB) were quantified by epifluorescence microscopy. Three sampling sites were established in the influence area of drain and one control site far from the discharge area. Average concentrations of VHB and VLB were 103 and 102 CFU mL-1, respectively. The TB ranged from 107 to 109 cells mL-1. The mean values of Mrelated to TB counts in the affected area were higher throughout the culture cycle compared to the control site, ranging from 1.09 to 27.35%. These results indicate that effluents modify the natural loads of bacteria in the discharge area, which could affect natural populations and the microbial balance of the area