Malaga Bay Research Articles

Potencial en Colombia para el aprovechamiento de la energía no convencional de los océanos

Colombia's geography sites which have greater potential for efficient and economically competitive electricity generation from non­conventional the ocean sources, due to their oceanographic conditions are evaluated in this article. Tidal currents were evaluated at Malaga Bay (Bahía Málaga) on the Pacific Ocean, finding that in order to exploit this type of energy some modifications to the access channels were needed to reach the required current velocity. This alternative was rejected because of the great magnitude of the modification works and negative impact on the bay. On the Guajira peninsula, on the Caribbean Sea, the energy content on the wind waves was valuated, finding by indirect methods an annual mean energy flux of 11.67KWm. A lime series of 28 days collected with a directional wave buoy on Bocas de Ceniza Barranquilla was analyzed, finding a mean energy flux of 16.11KWm', over the minimum levels (15KWm') needed for eco­nomic electricity generation. On San Andres island the thermal gradient of the ocean was analyzed, finding the oceanographic conditions required to take advantage of this energy, with capacity to assure the complete electricity demand on the island.

Effects of El Niño-Southern oscillation on the population dynamics of the tropical bivalve Donax dentifer from Málaga bay, Colombian Pacific

The population dynamics of a Donax dentifer (Hanley, 1843) population from Malaga bay, Colombia, was studied during two periods (August 1997–July 1998 and November 1999–February 2002) in order to investigate the effects of El Nino (EN) 1997/1998 and La Nina (LN) 1998/2000. The EN–LN cycle was strongly associated to an interannual precipitation and salinity variability in Malaga bay. Additionally, these factors were highly correlated with the reproductive cycle. Results indicate that EN had negative effects on the reproductive cycle, leading to weak, abnormal spawning events. In contrast, good spawning events were recorded during LN and post-LN. Based on these findings, an opportunistic reproductive strategy is proposed for this species. Overall growth performance (P) was higher during LN (P=4.41) than during EN and post-LN (P=4.20, P=4.28, respectively). These results indicate that D. dentifer has a higher overall growth performance compared to several tropical species reported in the literature. Total mortality rate of small individuals was higher during LN whereas that of large individuals was higher during EN. These results are best explained by recruitment variability and spatial differences between recruits and adults. Individual production and productivity were higher during LN, although annual biomass was relatively low. This, together with the results regarding growth and reproduction, suggests that food availability was higher during LN, thus positive effects under LN may be concluded. In contrast, EN seems to have negative effects on growth, reproduction and somatic production for this surf clam.

Contribution of larval growth rate vairability to the recruitment of the Bay of Málaga anchovy (SW Mediterranean) during 2000-2001 spawning seasons

Daily growth rates were estimated from larval anchovy (Engraulis encrasicolus) sampled in their main nursery grounds off the Bay of Malaga (SW Mediterranean) during the 2000 and 2001 spawning seasons. Significantly higher growth rates were observed in the 2001 larval population, representing a 20% increase through the larval size classes analysed. The decimated SW Mediterranean anchovy population experienced a successful anchovy recruitment during this year estimated at 13,000 tons for the Bay of Malaga by the acoustic evaluation of small pelagic resources. The size distribution of the recruited anchovy juveniles during 2000 and 2001 showed an increase of approximately 2 cm. Their corresponding anchovy spawning seasonality agrees with the estimates from the growth model fits of each year. Data on the environmental background for the two years sampled are provided by a historical quarterly monitoring project. Zooplankton showed a two-fold significant increase during July 2001, coastwise as well as offshore. No significant changes in surface temperature were observed between years. Instead of the usual summer spawning peak, anchovy peak spawning shifted towards early spring during the 2001 spawning season. The study provides evidence from field data on the relationships of larval growth variability and recruitment.

Changes in the macrobenthos of a sandy beach during "El Niño" 1997-98 in the Malaga Bay, Colombian Pacific

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.

Total Hydrocarbons in Waters, Superficial Sediments and Bioindicator Bivalves in the Pacific Colombian Coast

Contamination of hydrocarbons was determined from 1987 to 1993 in the Colombian Pacific. Water, superficial sediments and bioindicating organisms (bivalves) were collected at eight coastal stations of the Colombian Pacific. In general, contamination decreased with time along the Colombian Pacific Coast, though in some areas like the bays of Malaga and Solano levels are rising. The concentration of dispersed/dissolved hydrocarbons in water increased only in the Juanchaco and Solano stations in Malaga Bay. The highest concentrations of the three studied parameters were obtained in the first two years of monitoring, with a decrease in the following two years, followed by an increase.

Structural and seasonal variations of inshore fish populations in M�laga Bay, Southeastern Spain

A seasonal study of the inshore fish community was conducted in 1981 and 1982 at two stations in Malaga Bay (SE Spain). A total of 66 fish species were caught. Two families, Clupeidae (68.6%) and Engraulidae (28.5%), dominated in numbers, and Carangidae (54.3%) and Sparidae (29.1%) in biomass for both zones. There were two periods of high fish density in each zone: winter (2.2 g m-2) and autumn (2.0 g m-2) in the western zone and spring (2.95 g m-2) and summer (3.6 g m-2) in the eastern zone. Species diversity was relatively high during spring (2.95 and 3.00) and summer (2.32 and 2.44), showing clear variation with other zones of the Spanish coasts. An increase in diversity and number of fish species from north to south was observed. The area studied (0 to 15 m deep) serves as a nursery for larvae and young fish of several species appearing in the catches. The zoogeographical affinities of the fish species caught are: tropicals 25.7%, boreals 24.2%, Iberian-Moroccan 14%, endemics 4.5%.

Kleptoparasitic feeding by migrating skuas in Malaga Bay, Spain

Arctic Skuas were the most numerous skua in Malaga Bay, accounting for 94% of observed chases, with ten species of victim. Adult Arctic Skuas were more successful than immatures. No difference was detected between success rates of dark and light phase adults. Black‐headed Gulls and Sandwich Terns were the main victims of chases but there appeared to be far more victims than required to support the numbers of skuas visiting the region.

Observations on Noctiluca (miliaris ?)

ABSTRACT The following observations upon the structure and reproduction of a species of Noctiluca were made by Dr. Busch in the year 1849, and will be found in his work cited below, which was published in 1851. With respect to the structure of the animal, they perhaps present nothing in addition to what has already been made known to our readers in the Papers by Mr. Huxley and by Dr. Webb, in the present Volume of the ‘ Journal ;’ but as regards the reproduction and development of the Noctiluca, they afford several new points, and it is for that reason that we have thought it might be useful here to introduce them, and the more so, as it would seem these remarks by Dr. Busch had escaped the notice of Krohn, † as well as of Mr. Huxley ‡ and Dr. Webb.§ The species noticed by Dr. Busch occurred in great abundance in the Bay of Malaga, and is regarded by him, but we think, perhaps, erroneously, as distinct from N. miliaris. He terms it N. punctata, from the circumstance that the integument was covered with very numerous minute pigment-points; but the resemblance of his figure to N. miliaris is so striking, and the structure, so far as he describes it, so closely identical with that of the latter, that no doubt can be entertained as to the identity of the two forms.