Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Background. The crayfish Procambarus acanthophorus has a high potential for cultivation; however, it is necessary to evaluate its performance in polyculture with tilapia as a strategy for sustainable production in the rural sector where resources are limited. Goals. Assess the effect of polyculture of the crayfish and tilapia by measuring survival and growth. Methods. Three methods of cultivation with three replicates were evaluated: T1) crayfish monoculture, T2) polyculture crayfish/tilapia and T3) tilapia monoculture. Nine high-density polyethylene tanks (3 m diameter × 1.2 m deep) were used during the trial. The tilapia were fed commercial feed, 32/5% protein / lipids, while the crayfish were given commercial shrimp feed with 35/7% protein / lipids. The productive efficiency of mono- and biculture was determined based on survival feeding efficiency and growth performance. Results. Contrary to what was expected, interspecific competition, space, food availability, and weight gain of crayfish were similar in all treatments, whereas survival was influenced by the treatment, particularly during polyculture, where it was observed that tilapia affected the survival of crayfish. Unlike crayfish, tilapia maintained similar growth and survival in all treatments. Conclusions. The results indicate that polyculture of crayfish/tilapia in a recirculation system is possible and promotes the use of the water column. However, it is necessary to consider the antagonistic effect between species.

Background. Artisan fishermen along the southern Sinaloa coast catch alternative species, for example the Grapsus grapsus rock crab without biological and fishing controls, when their catches are reduced or when the season for catching certain fish has ended. Goals. We analyzed the size structure and biometric relationships of G. grapsus on Lobos, Venados, and Pájaros Islands of Mazatlán Bay, Sinaloa, Mexico. Methods. The cephalothorax width (CW) and weight (W) were analyzed during a one-year period (March 2012-February 2013). Results. 926 organisms were collected (519 males y 407 females). Pájaros Island had the greater percentage (37.4%) of collected organisms, followed by Lobos (34.2%), and Venados (28.4%) Islands. The greatest values were CW=74.5 mm recorded at Pájaros Island and W = 138.2 g at Venados Island and the lowest values were CW=13.9 mm at Pájaros Island and BW =1.1 g at Lobos Island. Means of CW and W were 41.4 mm and 31.5 g, respectively. The means of CW and W were statistically different between the islands (CL, p = 0.009; W, p < 0.015). Conclusions. High determination coefficients between the variables were obtained, indicating isometric growth. Specimens of G. grapsus increase their size quickly and their weight very slowly.  

Background: Benthic macroinvertebrates are commonly used as indicators of the biological condition of waterbodies. Both the benthic macroinvertebrates and the physicochemical properties of the water provide important information about the pollution of a water environment. Goals: To investigate the relationships between assemblage composition of Oligochaeta (Annelida), Chironomidae (Diptera), and other macroin­vertebrates with physical and chemical water variables in the Meric River, Turkey. Methods: This study was carried out by taking water and benthic samples at 8 stations at monthly intervals in order to determine what macrobenthic fauna exist in the Meric River and what environmental properties affect their distribution. Results: A total of 39 taxa were found and we determined that there is an average of 851 individuals per m2. Also, this study established the first records for Brachiura sowerbyii (Oligochaeta) and Pottashia alternis (Chironomidae) in the Turkish Thrace region. According to Shannon-Wiener index, while it was determined that Meric River has the highest diversity values with H’ = 0.845 at the station 4, the river has the poorest diversity with H’= 0.477 at the station 2. Also, we examined similarities of distribution of Oligochaeta taxa by station and month using the Bray-Curtis index. Accordingly, while stations 6 and 8 were determined to be the most similar to each other, stations 2 and 5 were the least similar. The relationships between Oligochaeta taxa and physical and chemical parameters of water were evaluated using the Spearman Correlation index. As a result, we found that water temperature, pH, electrical conductivity, hydrogen sulfide, calcium, magnesium, phosphate, chlorine, salinity, dissolved oxygen and biological oxygen have positive correlations with some species of Oligochaeta, while nitrate and nitrite have negative correlations with some species of Oligochaeta. Conclusions: We made a number of suggestions for sustainable usage of this river.

Background. Chirostoma humboldtianum (Valenciennes, 1835) is the first ichthyic species scientifically described in Mexico. Diversification processes of the genus Chirostoma Swaison, 1839 are related to the specialization of its mandibular apparatus; yet few studies exist regarding the digestive system in Atherinopsidae. In particular, the anatomical aspects of its mandibular, branchial, and hyoid skeleton, mandibular and pharyngeal dentition, and visceral musculature are superficially described. Goals. Analyze and describe the general organization of the digestive system of Chirostoma humboldtianum as part of its basic biology, in order to reveal the feeding processes useful for its conservation or culture. Methods. Adult specimens, previously fixed with formaldehyde and preserved in ethyl alcohol, were obtained. Their visceral skeleton and musculature and digestive tract were analyzed by dissections. Results. Major characteristics include presence of lower interpharyngeal cartilage, extensive expansion of levator operculi muscle over external opercular surface; presence of tendinous complex of A1 section of the adductor mandibulae muscle, which relates this section with the lacrimal and anguloarticular bones; presence of an additional section of pharyngoclavicularis externus muscle; insertion of retractor dorsalis muscle in vertebrae 2 to 4, absence of a stomach; and presence of a dental plate in each ceratobranchial 4. Conclusions. The organization of the digestive system of C. humboldtianum corresponds to an Atherinomorpha anatomic pattern, because of the absence of a stomach, among other characteristics; it particularly corresponds to the Atherinopsidae anatomical pattern due to its visceral skeleton organization. This organization, in particular, of the mandibular and pharyngeal adult dentition is characteristic of a carnivorous fish that includes other teleosts in its diet.  

Background. Microbial contamination of water bodies is causing major environmental and public health concerns in developing countries. Bacterial inclusion of inland waters can be of allochthonous and/or autochthonous origins. Goals. The aim of this study was to determine and compare the microbial contamination with environmental factors controlling colonization of bacteria in lagoon-lakes and freshwater lakes. Methods. Two lagoon-lakes and two freshwater lakes in Turkish Thrace were chosen and sampling was undertaken from October 2014 to August 2015 at seasonal intervals. While total heterotrophic bacteria, E. coli, coliform, and fecal coliform bacteria distributions from allochthonous and autochthonous origins were determined, environmental conditions of the ecosystems were also measured. While the Bray-Curtis Similarity Index and the Correspondence Analysis with Abundance Plot Analyses were used to determine the similarities of the sampling habitats, the Spearman’s Correlation Index was applied to clarify relationships between the environmental variables and the bacterial distribution. Results. The bacterial distribution was positively related to dissolved oxygen in one of the sampled lagoon-lakes (r = 1.0, p < 0.01) and negatively correlated with total dissolved solids and salinity in one of the sampled freshwater lakes (r = -0.95, p < 0.01; r = -0.80, p < 0.05, respectively). Conclusions. This research indicated that the saline water of the lagoon-lakes has limited the number of bacteria when compared with freshwater lakes.

Two new species of gymnosomatous mollusks from the central portion of the Gulf of California, Mexico are described based on radular characteristics. Pneumoderma cicimarensis sp. nov., has a similar morphology to Pneumoderma atlanticum pacificum (Oken, 1815), but differs in the presence of one lobe on the median portion of the wing, a lack of chromatophores in the body and the shape of the radular teeth. The second species Pneumodermopsis tacoi sp.nov., has a similar radula to Pneumodermopsis ciliata (Gegenbaur, 1855) but differs significantly in the number of rows of the radula and the shape of the central tooth.

Background. Panopea generosa is a large and long-lived infaunal clam with a considerable commercial value in Canada, United States and Mexico, in need of population genetic studies across its range of distribution. Goals. We set to develop new genetic markers (microsatellites) specific for P. generosa. Methods. We tested 30 microsatellite loci generated using next-generation genome sequencing (Illumina Hi-Seq 2500). Results. We identified eight as suitable polymorphic genetic markers. The number of alleles per locus ranged from 5 to 22 and heterozygosity from 0.429 to 0.818 (observed) and from 0.548 to 0.962 (expected). Deviation from Hardy-Weinberg equilibrium was found in three loci, after Dunn-Šidák correction, as a result of heterozygote deficiencies suggesting the presence of null alleles and linkage disequilibrium was found between two loci. Conclusions. These markers are highly informative and useful for population genetic studies aimed at informing management and conservation measures of this valuable resource.

Background. Goodea atripinnis is an omnivorous fish that is only found in the state of Aguascalientes. Its population is being drastically reduced and its survival is considered to be threatened. To avoid its extinction, ex situ breeding programs are being implemented. To implement these programs, however, it is necessary to have feeding plans that allow the nutritional needs of this species to be met. Goals. To evaluate the effects of different protein levels in the diet (25, 30, 35, 40 and 45 % PC) on the growth of G. atripinnis. Methods. A randomized complete-block design with five treatments (protein levels) and 3 aquariums per treatment was used, each aquarium containing 20 fish. The experiment lasted 150 days. Daily feed intake and changes in weight and length of each fish were recorded every 15 days. Results. We found differences in final weight and total weight gain (p <0.05) depended on protein levels. Both the growth rate and the total food intake increased with higher levels of protein. As a result, the feed conversion rate, protein efficiency, and Fulton (K) body condition factor improved. The Gompertz model showed that high protein levels increased standard weight and that the inflection point occurred at the same weight. Conclusions. With higher protein levels, the standard weight is reached at an earlier age, leading to greater development of the fish.