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Introduction: Swamps are lowland shallow tropical lakes in rivers floodplains, characterized by annual flood pulses that modulate changes in biotic and abiotic variables. Biological assemblages have different responses to flood pulses, remaining either undisturbed or with significant changes in composition and abundance. Objective: To evaluate how physical and chemical conditions are modified in mixed macrophytes microenvironments and ostracod species assemblages throughout a flood pulse in Rio Viejo swamp, Santander, Colombia. Methods: We characterized physical and chemical variables of microenvironments of aquatic floating plants, during four different hydrologic periods of the flood pulse: low, high, rising, and descending waters, at three stations where the flood pulse have the most important effect. Freshwater ostracods were collected from such microenvironments, identified, and counted. Results: Environmental conditions within microhabitats fluctuated following the flood pulse in the system. Three taxonomic families and six species of ostracods were observed. No differences in the composition and abundance of the spatio-temporal ostracod assemblages were observed, suggesting that they are buffered against environmental changes driven by hydrological fluctuations. Species abundance changed in response to environmental variability. Species such as Keysercypria sp. and Keysercypria sp. 2 are associated to shallower waters and more likely to dense aquatic vegetation cover. Other species showed to be more tolerant to hydrological fluctuations and may be related to ecological plasticity, species such as Cytheridella ilosvayi, Diaphanocypris meridana and Stenocypris major that have been recorded in a variety of aquatic environments and with distributions at continental scale. Conclusions: Flood pulses induced environmental changes in Rio Viejo Swamp, but microhabitats in mixed macrophyte cover seems to be buffered against the hydrological pulse, thus allowing almost undisturbed ostracod assemblages throughout a flood pulse. This updated tropical freshwater dataset contributes towards filling the knowledge gaps related to habitat suitability and distribution of ostracods communities in Colombia. [ABSTRACT FROM AUTHOR]

In Mexico, the state of Veracruz is the third most important in terms of biodiversity; however, the natural vegetation is currently in a state of fragmentation due to various anthropogenic activities that have had an impact on every municipality. In order to assess such impacts on the vegetation present in Molino de San Roque ecological park, biological material from the trees and shrubs was collected and processed in the herbaria of the faculties of Biology and Agronomy of the Universidad Veracruzana and Instituto de Ecología, A.C. Xalapa, Veracruz, Mexico. The study area within the park, located in the cloud forest, was found to contain a total of 58 species of trees and 48 of shrubs, distributed within 54 families, and 90 genera, giving an overall total of 106 species. [ABSTRACT FROM AUTHOR]