Comparison of basic limnological aspects of some crater lakes in the Cordillera Volcánica Central, Costa Rica
Umaña Villalobos, Gerardo
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Crater lakes share some morphological characteristics such as size, shape, situation inside a crater, usually high elevation, which have a definite impact on their limnology. In Costa Rica there are several crater lakes that may serve as an example of small tropical lakes to examine some relationships between morphometry and stratification. The results of different limnological expeditions to four such lakes are presented. The lakes are Barva, Botos, Cerro Chato and Hule. These lakes differ in their size and altitude. During each expedition the water transparency, the vertical profiles of oxygen and temperature were measured in a station at the middle of each lake as part of a more compressive study. The lakes were visited on several occasions for at least one year or more. The lakes which were relatively deep for their size, as judged from their relative depth such as Barva (Zmax= 7 m, Zr=6.2, 2840 masl) and Cerro Chato (Zmax= 18 m, Zr=9.6, 1020 masl), showed signs of frequent stratification, although at higher elevations and in the shallow Barva Lake this stratification may lasts only for short periods, whereas in deeper Cerro Chato Lake the mixing is mainly seasonal. On the other hand, Botos Lake (Zmax= 9 m, Zr=2.5, 2600 masl) that is relatively shallow for their size and widely exposed to the wind action, is clearly continuous polymictic, notwithstanding that its absolute depth is similar to smaller Barva, and finally Hule, a deep, exposed lake, but at low elevation is clearly oligomictic. Keywords: limnology, crater lakes, water column, morphometry, Costa Rica.