An ecological study of mayfly nymphs in Molawin Creek, Mt. Makiling, Laguna [Philippines].
1980
Realon C.B.R.
The effects of some ecological factors on the distribution, abundance and diversity of mayfly nymphs were studied in 5 different altitudinal zones of Molawin Creek, Mt. Makiling, Laguna from July 1977 to February 1978. Eleven species of mayflies were recovered from the creek. All species occurred in the upper 3 stations while 4 were absent in the lower ones. Five species, Afronurus sp., Baetis sp. 1, Caenis sp., Pseudocloeon sp. and Teloganodes sp., were most common and were found in all stations throughout the study. Baetis sp. 1 dominated populations in all stations and was found abundantly with Teloganodes sp. in the uppermost station 1, with Afronurus sp. and Pseudocloeon sp. In the next two station (II and III), and with Caenis sp. in the lowest stations (IV and V). Differential distribution and seasonal abundance are explained by differences in the physico-chemical proportion of the creek water such as type of substratum, current velocity, depth, and concentration of salts and dissolved oxygen, as well as rainfall pattern. Morphological adaptations of the most common species are also discussed as they affect the seasonal and spatial distribution patterns observed. Although all stations has similar indices of diversity, the upper stations II and III had the highest pooled values. Diversity is similarly related to the physico-chemical properties of the different stations while fluctuations in H values are attributed largely to rainfall distribution.
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