Biodiversity of zooplankton and benthos in canals around hot springs (biodiversity of thermal hot springs: zooplankton and benthos)

For the first year, a total of 23 zooplankton taxa belonging to four major animal phyla were identified in three neighboring canals and waterways in Cuyab, Pansol, Laguna [Philippines]. Rotifera had the highest number of taxa representing 56.5%, followed by Arthropoda 26.1%, Mollusca 13.0%, and Annelida 4.3%. The number of zooplankton taxa varied in the three sampled sites. For the entire sampling period, the highest number of taxa was recorded in site 1 (23), followed by site 2 (10), and site 3 (7). The difference may be attributed to the high nutrient input in site 1 from the effluents of nearby fish ponds. Fluctuations in zooplankton composition were observed across sampling periods in all sites. An increasing trend was evident in site 1, with the peak observed in Jan 2007. A total of nine taxa of benthic organisms were identified consisting of 78% gastropods, 11% bivalves, and 11% oligochaetes. The most abundant was Thiaridae representing 41.7% of the total count, followed by Melanoides 32.9%, and Pomacea 10.6%. Site 2 had higher mean abundance of macrobenthos than site 1. On the other hand macrobenthic taxa composition was higher in site 1 than in site 2. On the second year, another sampling site in Pansol, Laguna was identified. Only zooplankton was characterized in terms of spatial and temporal variations in species composition and abundance. Seventeen zooplankton taxa belonging to six animal phyla were identified in two sites in Laguna Hot Spring Resort in Pansol, Laguna. Protozoa was the most important group comprising 41% of the total zooplankton identified, followed by Rotifera with 34%, and Arthropoda with 10%. The least important groups were Oligichaeta, Nematoda and Gastropoda, with 6%, 7%, and 1% importance values, respectively. The overall mean abundance of zooplankton in the inner pool area ranged from 2 to 96 inds./cu m, with the highest abundance recorded in March 2008 and the lowest in Dec 2007. Similarly, the mean abundance of zooplankton in the canal outside the resort ranged from 0 to 225 inds./cu m, with the highest recorded in March 2008 and the lowest in Dec 2007. Similarly, the mean abundance of zooplankton in the canal outside the resort ranged from 0 to 225 inds./cu m, with the highest recorded in March 2008 and the lowest in Dec 2007. Fluctuations in zooplankton density were observed in both sites across sampling periods. Zooplankton density in the inner pool area was significantly lower than that of the outer canal in Sept 2007. This may be attributed to differences in temperature and dissolved oxygen between the sites. Higher dissolved oxygen in the outer canal may have favored the survival of a more diverse and abundant zooplankton community. Among the zooplankton, ciliates was the most abundant, followed by Bdelloidea, Centropyxis sp., and Brachionus angularis. The least abundant taxa were Brachionus sp., gastropod veliger larvae, and cyclopoidea adult. It was difficult to assess the effects of the resort activity on zooplankton community considering than human factors, which may have contributed to the observed differences, can not be clearly delineated from physico-chemical factors. However, it may be noteworthy that some species such as Brachionus angularis and Centropyxis may indicate eutrophication in these areas.