Abstract

  The major hydrological characteristics of the coastal lagoons of Yucatán and their relationship with the space-time pattern of the primary producer communities are described. The weather patterns in the region play an important role in the seasonal changes of nutrient inputs, which are related to the groundwater discharges. The fluctuations of the mean sea level in response to freshwater discharges and frontal systems influenced the differences observed in the residence time of water, which could play an important role in the accumulation of toxic substances from sewage discharges and biological metabolism. The spatial distribution of primary producers was heterogeneous with high biomass production in the middle zone of the lagoons. The dominant group in each system changed seasonally in response to the coupling between external forces and their life cycles; however, the submerged macrophytes might be the principal group in these shallow aquatic ecosystems. The mangrove vegetation experienced strong differences in their structural development which could be used as a signal of the impacts observed in the area. Though there is no river in the region, the mangrove vegetation was well represented in the North Coast and irregular freshwater inputs favored the dispersion of this community. However, because the seasonality of these freshwater inputs did not show a better structure, their contribution to total primary production should be limited in some areas to a specific period of the year. The heterogeneity observed in the hydrology and primary producer communities suggested a high diversity and the existence of different food webs that offer various potential uses. However, for adequate management polices, these uses must be planned considering the space-time pattern of the hydrology and primary producers. © 1999 Elsevier Science Ltd and AEHMS. All rights reserved.

Keywords: Phytoplankton; Submerged aquatic vegetation; Mangrove; Nutrients; Groundwater; Coastal ecosystems