Kajian Aspek Ekologis Dan Daya Dukung Perairan Situ Cilala

Ecological aspect (morphometry, a complexity of community structure, trophic state, and carrying capacity) are one of basic information to build comprehensive management concept of aquatic ecosystem, as Lake Cilala. The concept was addressed to develop ornamental fish floating cage and natural fishery activity. Lake Cilala is a longwise shape small lake with maximum length, average width, and average depth as 1141 m, 161 m, 2.67 m respectively. Lake Cilala has various genera of phytoplankton and zooplankton, 8 genera of benthos, 5 genera of aquatic plants, and 12 fish species including planktivore, herbivore, and carnivore fishes. Those organisms established food chains, by grazing and detritus food chain. The trophic state of Lake Cilala was categorized as middle to heavy eutrophic level by Trophic State Index (TSI). The carrying capacity analysis of Lake Cilala is 130 tons/year. It is resulted a possibility to increase ornamental fish floating cage to 165 units from 300 existed units. Furthermore, the carrying capacity for natural fish was reached 3.77 tons/year

Dinamika Sel Heterokis Anabaena Azollae Dalam Media Tumbuh Dengan Konsentrasi Nitrogen Berbeda

Anabaena azollae is an heterocyst Cyanophyceaean as symbiont of Azolla sp. Anabaena azollae is able to fix N2 from atmosphere and transform it into ammonium by its heterocyst cell. This research was conducted to study the influence of different concentration level of nitrogen to the dynamic of Anabaena azollae heterocyst cell. Research was conducted by observing heterocyst cell and variation nitrogen concentration in growing media in 21 days. In each sampling of Azolla sp., heterocyst observation was conducted for every 1000 cells in Anabaena azollae filament colonies. Result showed that media with 0 mg/L nitrogen has the highest number of heterocyst cell. In early observation, there was increasing of ammonium concentration in media 0 mg/L and 5 mg/L. Media without nitrogen addition has generated the highest number of heterocyst cell