RESUMEN
ABSTRACT Mining activity generates transformations in aquatic ecosystems and adjacent areas, as well as the creation of land depressions or "lagoons" that act as water reservoirs where aquatic communities develop, including the phytoperiphyton. Considering the role of this community in these environments, the purpose of this research was to study the phytoperiphytic community present in lagoons generated by mining processes, in the San Juan basin, Chocó (Colombia). Lagoons with different formation times were selected: 1-5 years, 5-10 years and 10-15 years; three lagoons for each time period. Physical and chemical variables were measured, and phytoperiphyton was collected, using an 8cm2 quadrant, obtaining a scraping area of 120cm2. The community was composed of six divisions, nine classes, 16 orders, 24 families and 33 genera, for a total density of 13108 org/cm2. The lagoons of 10-15 years presented the highest density, with Bacillariophytes as the most representative in all the studied lagoons, both in density and richness. There were differences in density between lagoons, but not in specific richness and diversity. Similarity values indicate that the lagoons have little variability in their phytoperiphytic communities. Conductivity and dissolved total solids are the variables with the greatest variation throughout the study; there are significant differences between lagoons for the variables dissolved oxygen, pH and alkalinity (p<0.05). This study constitutes a baseline for understanding the ecological dynamics of lentic environments generated by mining processes and on the development of phytoperiphytic communities in them.
RESUMEN La actividad minera genera transformaciones en los ecosistemas acuáticos y zonas adyacentes y, entre ellas, se crean depresiones en el terreno o "lagunas", que actúan como reservorios de agua, en los que se desarrollan comunidades acuáticas, como el fitoperifíton. Considerando el papel de esta comunidad en estos ambientes, el propósito de esta investigación fue estudiar la comunidad fitoperifítica presente en lagunas generadas por procesos de extracción minera, en la cuenca del San Juan, Chocó (Colombia). Se seleccionaron lagunas con diferente tiempo de formación: 1-5 años, 5-10 años y 10-15 años; tres lagunas por cada periodo de tiempo. Se midieron variables físicas y químicas y se colectó fitoperifíton, utilizando un cuadrante de 8cm2, obteniéndose un área de raspado de 120cm2. La comunidad, se compuso de seis divisiones, nueve clases, 16 órdenes, 24 familias y 33 géneros, para una densidad total de 13108 org/cm2. Las lagunas de 10-15 años presentaron la mayor densidad con las Bacillariophytas, como las más representativas en todas las lagunas estudiadas, tanto en densidad como en riqueza. Existieron diferencias en densidad entre lagunas, pero no en la riqueza específica y diversidad. Los valores de similaridad indican que las lagunas presentan poca variabilidad en sus comunidades fitoperifíticas. La conductividad y los sólidos totales disueltos son las variables de mayor variación, a lo largo de estudio, existiendo diferencias significativas entre lagunas, para las variables oxígeno disuelto, pH y alcalinidad (p<0,05). Las variables pH y conductividad, se relacionaron positivamente con la densidad de algunos grupos fitoperifíticos. Este estudio, se constituye en una línea base para el conocimiento de la dinámica ecológica de los ambientes lénticos generados por los procesos mineros y sobre el desarrollo de las comunidades fitoperifíticas en ellos.
RESUMEN
Natural marine biofilms provide signatures of the events that occur over a period of time and can be used as bioindicators of environmental changes. Hence, the effects of temperature (30 and 34°C), pCO2 (400 and 1500µatm) and nutrients (unenriched and enriched f/2 media) on the marine biofilm were evaluated using a 2×2×2 factorial design. In unenriched condition, acidification significantly increased the abundance of phytoperiphytes whereas reduced that of bacteria and it was vice versa in the enriched condition. Warming had significant negative effect on the abundance of both phytoperiphytes and bacteria, except in unenriched condition wherein it favoured bacterial growth. Synergistically, acidification and warming had deleterious effects resulting in further reduction in the abundance of both phytoperiphytes and bacteria, except in enriched condition wherein bacterial abundance increased. Such changes in biofilm communities in response to warming and acidification can have cascading effect on the subsequent build-up of macrofouling community.
