Browsing by Author "Cogua, Pilar"
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Item Influences of environmental conditions in the fish assemblage structure of a tropical estuary(Marine Biodiversity, 2019-12-19) Molina, Andrés; Duque, Guillermo; Cogua, PilarThree fish assemblages (functional groups according to estuary use) were examined, which presented different responses to environmental variations, mainly associated to the dry and rainy seasons and high and low salinities and temperatures in the Buenaventura Bay estuary, Colombia, Tropical Eastern Pacific. In total, 4674 individuals were collected, belonging to 69 species of 29 families. The most abundant species was Sphoeroides trichocephalus (35% of the total density). The assemblage of estuarine-resident fishes showed high tolerance to environmental variations since these were present all along the estuary and throughout the year. The assemblage of marine estuarine–dependent species was associated with the rainy season and low salinities and temperatures. The assemblages of marine estuarine opportunist fishes were associated with areas of higher environmental variability in both seasons, dry and rainy. Fish species belonging to the same functional group showed variations in their response to environmental changes which evidenced complex spatial and temporal dynamics. Understanding these changes is necessary to generate effective management plans based on scientific ecological knowledge, which include environmental impacts present in this estuary such as microplastics, heavy metals, and effects of dredging, and their effects on the ecosystem.Item Mercurio en peces de la bahía de Buenaventura(Universidad Santiago de cali, 2016-05-01) Duque, Guillermo; Cogua, PilarEl mercurio es un metal persistente que puede causar graves efectos ecológicos en los ecosistemas. El objetivo del presente estudio es relacionar las anormalidades nucleares de los eritrocitos (ENA), la frecuencia de eritrocitos inmaduros (EI) con la concentración de mercurio total (HgT) en peces de la bahía de Buenaventura. Las especies colectadas son Lisa (Mugil cephalus), Loca (Stellifer fuerthii) y Canchimalo (Cathorops multiradiatus). Todas las especies estudiadas presentaron mercurio en la sangre. Las especies M. cephalus y C. multiradiatus muestran altas correlaciones negativas entre ‰ ENA y las concentraciones de HgT en sangre (0.76, 0.91). Para S. fuerthii y C. multiradiatus se presentan altas correlaciones negativas (0.77, 0.67) entre ‰ EI con los niveles de HgT en sangre. Las variables biológicas fueron relacionadas con los niveles de HgT en músculo, donde C. multiradiatus obtuvo correlaciones fuertes (0.67, 0.69) para peso total y para la longitud total. Todas las especies bioacumulan activamente el HgT, confirmando la presencia de este contaminante en el ecosistema.Item Mercury dynamics in macroinvertebrates in relation to environmental factors in a highly impacted tropical estuary: Buenaventura Bay, Colombian Pacific(Springer, 2019-12-10) Gamboa García, Diego Esteban; Duque, Guillermo; Cogua, Pilar; Marrugo-Negrete, José LuisThe environmental health of Buenaventura Bay, a highly impacted tropical estuary, is influenced by numerous human activities, including mining upstream. Large- and small-scale fishing plays an important role in the local economy, so we investigated the dynamic processes of bioaccumulation of mercury at basal trophic levels. Four samples were taken at each of the four locations in Buenaventura Bay during each of the four seasons of 2015. We measured the total mercury content (T-Hg, dry weight) in sediments and in muscle tissue across 17 macroinvertebrate species. The most abundant were the blue crab (C. arcuatus) and the mantis shrimp (S. aculeata aculeata). Blue crab showed an average muscle T-Hg value exceeding the limit of 0.2 g·g-1, which is the maximum T-Hg level suggested for food consumption by vulnerable humans and populations: pregnant women, children, and the community that feeds from this source of protein on a daily basis. It was found that, 6.22% of individuals exceeded the 0.5 g·g-1 level, which is the maximum T-Hg level suggested for food consumption by the general population: the population that consumes it sporadically. Significantly high values of T-Hg in blue crab and mantis shrimp occurred during low salinity conditions in the estuary, suggesting that Hg mainly originates from river runoff during the rainy season. Nevertheless, the biota-sediment accumulation factor (BSAF) was favored in high salinity, which could mean greater availability of Hg for higher levels of the estuarine food web in the dry season and in marine waters. In general, the T-Hg levels in some samples exceeded 0.2 g·g−1. Therefore this pollutant must be monitored due to its biomagnification potential and as a threat to human health, especially that for the local population of fishermen and their families.Item Relaciones tróficas de cinco especies de peces de interés comercial en la bahía de Cartagena, caribe colombiano(Boletin de Investigaciones Marinas y Costeras, 2013) Cogua, Pilar; Jiménez-Reyes, M.F.; Duque, GuillermoTrophic relationships of five species of commercial interest in Cartagena Bay, Colombian Caribbean. Cartagena Bay is a highly productive habitat which supports important aquatic communities and is considered an estuarine environment. During the sampling season, five commercial fish were captured: ladyfish (Elops smithi), machuelo (Opisthonema oglinum), mullet (Mugil incilis), sea bass (Centropomus ensiferus), and corvina (Cynoscion jamaicensis), all which stomach contents were analyzed. From all the fish captured, 82.6% presented contents in their stomachs, which were separated into 57 items, such as benthic microalgae, dinoflagellates, cyanophytes, sponges, mollusks, annelids, crustaceans, and fish. According to the Importance Relative Index (IRI), E. smithi, C. ensiferus, and C. jamaicensis were classified as third order consumers, O. oglinum as a second-order consumer, and M. incilis as first order consumer. The most contrasting result compared to other studies, is the found for O. oglinum, suggesting that this species is not only a filter feeding, but also a scale eater (lepidophagy).Item Structural and compositional dynamics of macroinvertebrates and their relation to environmental variables in Buenaventura Bay(INVEMAR, 2018-01-01) Gamboa-García, Diego Esteban; Duque, Guillermo; Cogua, PilarBuenaventura the to environmental distribution bay of is variables. macroinvertebrates characterized The objective by a in great the of bay dynamic the and present its of habitat, work environmental was however to determine variables. it is necessary the There espatio-temporal to is document descriptive on variation information its dynamics in the concerning in structure relation and composition of macroinvertebrates and their relationship with the environmental variables. Four sampling (April-June-September-November) were carried out throughout 2015, in four stations (Estuary River-Internal Estuary-External Estuary-Marine Estuary). At each station three samples of sediments, physicochemical variables of the water and macroinvertebrates were collected. A total of 532 individuals were found in 17 species and 9 families. The abundance varied from 0.7±1.2 to 29.7±7.4 individuals per trawl and the richness varied from 0.3±1.2 to 4.7±1.2 species per trawl. The multiple regression analysis suggests an influence of the variables salinity and percentage of clays on the structure and composition of macroinvertebrates in the bay. The abundance and richness of macroinvertebrates was higher when the salinity conditions prevailed in the estuary. © 2018 INVEMAR. All rights reserved.