| To improve the management of the coastal ecosystems in North-western Mexico, a study on the biology, chemistry and physical properties of these important aquifers was initiated in 1990. One of the systems to be studied in detail was the Altata-Ensenada del Pabellon lagoon (Sinaloa, Mexico), whose benthic communities were analyzed by the Benthic Invertebrates Research Group of the Instituto de Ciencias del Mar y Limnologia, Estacion Mazatlan (ICMyL-UNAM).;The study of the benthic communities involved the analysis of the distribution and abundance of meiofauna, of which no data were available for the Mexican Pacific coast.;From this study, the numeric dominance of harpacticoids, only outnumbered by the nematodes, was observed. In order to continue the analysis of harpacticoids, unknown from the Mexican Pacific coast so far, and indepth study on its systematics and ecology started in 1995, and constitutes the main body of the present thesis.;Detailed comparison and careful description of the encountered harpacticoids revealed the presence of 20 families. In total 63 species were identified, of which 57% are new to science.;In addition, the subspecies Longipedia helgolandica santacruzensis Mielke is raised to the species rank, Longipedia santacruzensis Mielke comb. nov., Eoschizopera (Praeoschizopera) indica Rao & Ganapati is transferred to Eoschizopera (s. str.), while Eoschizopera spec. B Mielke 1995 is allocated to Eoschizopera (Praeoschizopera), and Schizopera osana Mielke and Schizopera spec. A Mielke 1995a are attributed to a new subgenus, here defined.;Pseudostenhelia wellsi Coull & Fleeger is fully redescribed and compared with specimens from the type-region. Based on these observations, the setal formula of the natatorial legs as was presented by Coull & Fleeger (1972). Wells (1967) and Ranga & Reddy (1984) is amended.;In chapter V, a brief discussion of the most relevant biogeographic models of meiofauna is presented. Additionally, a brief biogeographic analysis of a species-group of the genus Longipedia (Longipediidae) and the genus Scottolana (Canuellidae) have been included under the form of work hypotheses which should be tested in future studies.;The analysis of abundance and distribution of harpacticoids in Ensenada del Pabellon lagoon have been presented elsewhere (Gomez Noguera & Hendrickx, 1997). Only some additional comments are included herein.;Finally, the analysis of the diversity of 4 communities is presented and discussed. It is concluded that the diversity of the harpacticoid communities in the four stations are negatively affected by organic enrichment through the sewage outlets of agro-industrial activities in the north-eastern part of this ecosystem. |
