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

 Different experiments about the accumulation capacity for copper and zinc were carried out on the marine microalgae Nannochloropsis gaditana Lubián (Eustigmatophyceae). A 24-hour study of the evolution of accumulated metal in the beads revealed two possible accumulation phases. Accumulation differences between free and immobilized microalgal cells were investigated finding no differences for copper, and little differences for zinc. Free cells accumulated practically 100% Cu or Zn in the media under experimental conditions. Experiments in order to compare the accumulation capacity of living vs. dead cells were designed too, obtaining the largest accumulation levels for both metals in the beads containing immobilized living microalgae. In experiments carried out in continuous-flow reactors, beads with entrapped cells showed to be more efficient removing Cu and Zn than beads without cells. In all the experiments, the calcium alginate beads showed strong affinity for Cu. Similar results were obtained when accumulation by packed beads in columns was tested, but efficacy was higher if this design was used (beads with cells retain 80% of Cu introduced in the column).

This work characterizes and compares the community of anemones at two coralline areas in the Tayrona National Natural Park, in the Colombian Caribbean, and also relates the species that were found with some important characteristics of the reef community as well as with factors that can condition its structure. The statistical tests performed allowed to differentiate two kinds of landscapes: the shallow mixed coral reef and the deep one. A total of 15 species of anemones were found, four belonging to the Order Corallimorpharia and 11 to the order Actiniaria, distributed over the coralline landscapes of the area. The tests used to determine the distribution of anemones inside the corridors measured, showed the formation of two similar groups of corridors to those obtained for the landscape that in its turn, represent two groups of anemones, those of shallow reefs and those of deep reefs. The tests used for each kind of anemone in respect to the characteristics of the reef environment suggest that each species has its own preferences regarding the habitat selection. However, relating the anemones with the landscape, anemones with the presence of certain coral species and anemones with the general reef landscape can create two basic categories.

The step to convert alginic acid to sodium alginate on the alginate extraction process was studied, using the brown seaweed Macrocystis pyrifera as raw material. The effect of alcohol volume, alcohol-water proportion, pH, and treatment time on the yield and viscosity of the alginate obtained was analyzed. Seven volumes of the mixture alcohol-water in proportion 50:50 were experimented, from 9 to 15 mL g–1 alga. The yield and viscosity were not significantly different in any of the volumes used, however, the stirring with the volume of 9 mL g–1 alga was less efficient, therefore the minimum volume to use in this step was 10 mL g–1 alga. The appropriated proportion of the mixture alcohol-water was determined using five proportions: 50:50, 47:53, 44:56, 40:60, and 37:63. The highest yield and viscosity were obtained using the proportion 50:50. Five pH values from 6 to 10 were experimented to determine the optimum pH for the conversion reaction. The best results were obtained using a pH from 7 to 8 in the alcoholic solution of the conversion step. To determine the minimum time required for the conversion reaction, the fibers of sodium alginate were stirred in an alcoholic solution for 20, 30, 40, 50 and 60 min. The yield and viscosity obtained were not significantly different, therefore, the minimum time to carry out the conversion reaction was 30 minutes to assure a complete reaction. The use of a double planetary mixer is proposed to carry out this step at other level.

 Changes in the macrobenthic community of a sandy-beach were studied during the "El Niño" 1997-98 event at the Malaga Bay, in the central Colombian Pacific. Species composition was recorded monthly from October 1997 to May 1998 at four tidal levels, and species diversity (Shannon-Wienner, H') and richness were calculated. In order to analyze community structure changes, multivariate ordinations were performed (non-metric multidimensional scaling) and species responsible for the observed temporal changes were discriminated using a dissimilarity index. Differences in species diversity and richness were related to a seriation pattern in vertical species distribution . A common pattern of structure change was found at four tidal levels on the beach. Population reduction or increase of some species and vertical modifications of the spatial distribution patterns were the main source of temporal community change.

 In this work, artificial neural network (ANN) algorithms were used to predict time series of the oceanographic variables Southern Oscilation Index (SOI) and sea surface temperature anomaly (SSTA). The finite impulse response neural network (FIRNN) was applied to data obtained from the NOAA. In order to determine the most efficient FIRNN architecture, several experiments were made varying different parameters. The best predictions were obtained for a network with one input neuron and 10th-order filters in the input layer, two 8-neuron 5th-order filter hidden layers and one output neuron. All the networks were trained with the temporal backpropagation learning algorithm, using the sigmoid transfer function at the hidden layers and a linear output. The learning rate was 0.001. In most experiments a normalized mean square error of 0.4 ± 0.1 and a correlation coefficient between the original and the predicted series greater than 0.8 were found. From a comparison with other SSTA prediction methods, the results obtained with the neural network were the best ones for the short term forecasting case.

This article deals with a short analysis of the journals indexed by the National Council of Science and Technology (CONACyT) in Mexico and their wordwide impact. It also compares the impact factor of the journal Ciencias Marinas to other journals related to marine sciences around the world, as well as their impact according to the Institute of Scientific Information (ISI), based on the volumes of the News Journal Citation Index (JCR). In respect to Ciencias Marinas, it was first integrated to ISI products by appearing in Current Contents back in 1992, with an aproximate impact factor of 0.22; this was calculated again in 1995 rising to 0.24. From 1995 to 1996, Ciencias Marinas five-folded its number of cites, and by 2000, it reached an impact factor of 0.333. The journal Ciencias Marinas thanks the hundreds of authors and coathors of the articles that were published in our journal since 1974 until 1997. Thanks to you, to your effort and contributions to Science, Ciencias Marinas has reached the quality standards that allow the satisfaction of being indexed among ISI products, neither being this its only pride nor the most important.

 It is desired to represent, as good as possible, a series of data by means of certain functions with free parameters. "As good as possible" means that these parameters ara chosen so that the residuals, the difference between data and fitting functions, be as small as it is feasible. Our objective is not limited to finding the parameters of the best fit, but we also wish to know something about their uncertainties, this is, how well they are determined, given the errors of the original data as well as the imperfection of the fitting. Finally, supposing that we use the parameters of the fit in the calculation of other variables, we also want to have an estimation of the uncertainties of the latter. In order to do that, we imagine basic properties, wich we call "hypothesis", and then proceed from there with mathematical rigor. It is not superfluous to remember that the conclusions at wich we arrive depende on the hyphotheses done throughout the way, including the idea that useful information can be extracted from a least squares fit, of those data by these functions.

Notoacmea biradiata (Reeve, 1855) is an abundant intertidal limpet on the rocky shore of the Colombian Pacific coast. This paper reports a field factorial experiment on shell-size variation of N. biradiata as a response to two independent factors: intertidal gastropod density and shore height above sea level. Four rocky shores were selected on the Colombian Pacific coast, two in Gorgona Island and two in Utr?Cove. The intertidal gastropods density was determined in each rocky shore using the transect-quadrant technique. Significant differences were observed in the gastropod densities between study sites: low density in the rocky shores of Utr?Cove and high density in the rocky shores of Gorgona Island (P < 0.009). A factorial sampling was conducted to determine the effect of the density and height on the shore over shell-length, shell-height and shell-thickness. A twoway ANOVA and a least-squared regression was used to determine whether the shell-sizes differ between varying densities and shore heights. Intertidal gastropod density was found to be the dominant factor in determining basal shell length (ANOVA, P < 0.001) and shell height (ANOVA P < 0.05) changes. Thus, at low population densities the shells are larger and taller. The height on the shore did not influence the shell-size of N. biradiata (ANOVA, P > 0.30).

The immune response in mollusks has an important role as a defense against bacteriae, fungi, protozoa and metazoans. The hemocytes are responsible for generating different kinds of innate responses such as: phagocytosis, encapsulation and production of cytotoxic substances and antibacterial peptides. Through light microscopy we estimated the hemocyte number using a Neubauer chamber. Over hemocytes monolayers we measured the phagocytic ability on yeasts. The haemolytic activity on rat's erythrocytes was tested by hemoglobin release and the production of anion superoxide was quantified by the reduction of NBT (Nitro Blue Tetrazolium). We determined that the immune system from Argopecten purpuratus was defined by two types of hemocytes: hyalinocytes and granulocytes. The number of hemocytes circulating in the hemolymph showed a seasonal variation, having a greater increase during winter than in autumn. The hemocytes phagocytized yeast in the absence of plasma when they were opsonized, showing a remarkable increase in phagocytosis. Plasma and hemocytes have an equivalent hemolytic ability against rat?s erythrocytes. The hemocytes present production of anion superoxide that increases considerably over the control with the use of zymosan and, decreases with the use of the superoxide dismutase. The results show that hemocytes from Argopecten purpuratus are able to display different defense mechanisms during the cellular response that could be used as tools to evaluate the immune system of mollusks in the near future.

With the aim of contributing with technical information necessary for the management of the rock oyster fishery in Sinaloa (Mexico), a survey of the rock oyster Crassostrea iridescens was done using individual buoys hooked to the rocky bottom in order to recover and identify 99 tagged specimens, including estimates for natural mortality (M), growth rates and the relationship between total length and total weight. Data for rock oysters were recorded during two sampling phases (March-April and September-October 1995), and in both cases survival rates (S) were near 80% to give a final estimation of M = 2.2y–1. The lengthweight relation indicates a negative allometric growth, with coefficient values significantly smaller than 3.0 for each period (2.18 and 2.61). The values for the growth parameters of the von Bertalanffy model were L∞ = 134 mm and 155 mm, K = 0.069 and 0.098, t0 = –0.66 and –0.40 for each period. The results agree with the annual environmental variations present in the study area, and appear sufficiently reliable for use in the management of the rock oyster.