Se presenta una lista sistemática de peces recolectados durante 2014 y 2015 en la Reserva de la Biosfera Pantanos de Centla con un incremento del 25% de su diversidad principalmente por la presencia de peces diádromos. El inventario comprende 75 especies, que representa el 37% de la ictiofauna en la cuenca Grijalva-Usumacinta, de las cuales cinco especies fueron no nativas invasoras donde el bagre armado (Pterygoplichthys spp.) fue el que presentó la mayor frecuencia de captura. Se identificaron 48 especies migratorias (38 diádromas y 10 potamodromas). La dominancia de peces diádromos y su presencia en sistemas de lagunas y fluviales nos indica el mantenimiento de la interconexión hidráulica entre ríos y lagunas. En los muestreos, se observó la ausencia de siete especies dulceacuícolas que fueron comunes en publicaciones previas, lo anterior puede ser debido a la disminución de hábitats como consecuencia de las actividades humanas y la introducción de especies invasoras. En este estudio se resalta la necesidad de mayores estudios enfocados a la biología de varias especies, con el objetivo de aclarar su condición de potamodromia y comprender la migración lateral que algunas especies presentan durante su ontogenia para satisfacer sus necesidades eco-fisiológicas.

The intake of microplastics by freshwater fishes has been scarcely studied, and it is not yet clear whether the amount of particles these vertebrates ingest is associated with their feeding strategies. Hence, this study is focused on the suckermouth armored catfish (Pterygoplichthys spp.) under the hypothesis that, due to its detritivorous habits and demersal distribution, it may show evidence of the presence of microplastics in the sediments of a lake located in the Metropolitan Area of Villahermosa. A total of 21 organisms contained plastic microfibers throughout their digestive systems. These were treated with three solutions (hydrogen peroxide, potassium hydroxide, and sodium hypochlorite) to separate the microplastics. A total of 147 plastic particles of two categories were collected: microfibers (92%) and fragments (8%). Considering these results, as well as evidence in the literature, these species may constitute a global indicator of the incorporation into the trophic chain of microfibers deposited in the sediments of freshwater ecosystems.

Water quality indicators have been tied to natural or man-made surface hydraulic connection (SHC) conditions. Among these, temporally connected lakes (TCL) are hydraulic intermediates between isolated (IL) and permanently connected lakes (PCL). Therefore, the aim of this study is to answer if water quality indicators can estimate the possible overlap between the two opposed conditions of SHC (IL and PCL) with the intermediate one (TCL) in lakes with similar modifications in the water level regulation at the basin level. Among nine water variables sampled in six lakes with the three SHC conditions mentioned, chlorophyll a (Chl-a), Secchi disk (SD), and total phosphorus (TP) were identified as quality water indicators through principal component analysis. Furthermore, said indicators were used to measure their overlap and trophic state index deviations. The Chl-a, SD, and TP values in TCL showed a 0.72 overlap of PCL and IL. TP surplus measured in all the lakes was meaningful in urbanized ILs and lessened in a rural lake (PCL6) with submerged rooted macrophytes. The estimated overlap of trophic indicators between TCL, IL, and PCL in this study must be verified at a global representative scale for predictive and preventive use in the conservation of tropical coastal plain lakes.

The variability of 11 physicochemical and biological variables in the water column was analyzed in lentic and lotic environments during two intraannual water level periods over 10 non-consecutive years within a hydraulically interconnected alluvial zone of a tropical fluvial system. The evaluation included the limnological characterization, a principal component analysis (PCA) based on eight key variables, and the examination of inherent and recurrent variability of data through violin plots. The limnological characterization and PCA, both based on variable-level analysis, partially explained the variation among four conditions: lotic high water level, lentic high water level, lotic low water level, and lentic low water level. Whereas, the analysis of inherent data variability pointed out three conditions associated with kinetic energy and water column processes. First, the fluvial explained primarily by sediment transport and nutrient enrichment. Second, lateral homogenization of electric conductivity, water transparency and dissolved oxygen saturation. Third, lentic in low water level, when lakes worked as bioreactors exhibiting high biology productivity and oxygen supersaturation. In conclusion, the inherent data variability of the key variables supports the hypothesis that the physicochemical variability is driven by recurrent and interactive conditions. These findings show that the analysis of data variability provides a useful tool for understanding water column dynamics and identifying the principal conditions regulating the ecological functioning of tropical riverine wetlands.