Dolphins of the genus Sotalia are found along the Caribbean and Atlantic coasts of Central and South America and in the Amazon River and most of its tributaries. At present, the taxonomy of these dolphins remains unresolved. Although five species were described in the late 1800s, only one species is recognized currently (Sotalia fluviatilis) with two ecotypes or subspecies, the coastal subspecies (Sotalia fluviatilis guianensis) and the riverine subspecies (Sotalia fluviatilis fluviatilis). Recent morphometric analyses, as well as mitochondrial DNA analysis, suggested recognition of each subspecies as separate species. Here we review the history of the classification of this genus and present new genetic evidence from ten nuclear and three mitochondrial genes supporting the elevation of each subspecies to the species level under the Genealogical/Lineage Concordance Species Concept and the criterion of irreversible divergence. We also review additional evidence for this taxonomic revision from previously published and unpublished genetic, morphological, and ecological studies. We propose the common name “costero” for the coastal species, Sotalia guianensis (Van Bénéden 1864), and accept the previously proposed “tucuxi” dolphin, Sotalia fluviatilis (Gervais, 1853), for the riverine species.

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Waste stabilisation ponds are an efficient means of wastewater treatment in many parts of the world wherever suitable land is available at reasonable cost and solar energy is an abundant energy resource. This study evaluated the removal of total coliforms TC, faecal coliforms FC and coliphages C in waste stabilisation ponds functioning as a pilot system in the tropical climate of Maracaibo, Venezuela. Sampling points included raw sewage and each pond effluent. Turbidity, pH and temperature were recorded. The results for raw sewage show average levels of 4.1×106 TC, 2.8×106 FC and 7.0×105 C/100mL. Temperature, pH and turbidity ranges between 26–31°C, 6.2–9.5 and 15–98 NTU respectively. Removal of microorganisms in the three systems ranged between 93–98%. Despite the high removal efficiency of microorganisms, the final effluents showed average counts of 5.4×104−1.4×105 TC, 5.2×104−1.3×105 FC and 1.6×104−4.7×104 C/100mL. This study shows that the microbiological quality of the final effluents did not achieve the WHO water quality requirement for FC (103/100mL); therefore, they cannot be used for irrigation. Additional treatments, such as slow sand filtration, are needed in order to improve the quality of the water.

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