Effect of Different Tilapia Feeds on the Species Diversity, Richness and Evenness of Benthos Community

Abstract

Aquatic macro-invertebrates play significant role in responding to a variety of environmental conditions of rivers and streams and therefore may be used as bio-indicators for water quality assessment. They are important for the assessment of water quality of rivers, lakes and streams as bio-indicators because they can be easily caught and seen with naked eyes. This study was conducted to assess the effect of different experimental diets on the species diversity, richness and evenness of benthos community in tilapia ponds. This study was conducted in total 36 ponds where two different feed experiments (two diets for experiment-I and two other diets for experiment-Z) (feed-I, feed-2) with two doses (single dose and double doses) were applied in tilapia culture to assess its effects on the macro-benthos community structure in culture system. There were two control groups (CI, C2) and four treatments (TI, T2, T3,T4) on the type of feed and number of doses with 6 replications for each. Benthos species diversity, richness and evenness were determined by seven sampling in which 4 samples were taken under experiment-I and 3 samples were taken under experiment-2 in the tilapia culture period using Ekman dredger. The study revealed the presence of three major groups of macro-benthos; gastropods, Oligochaeta and Bivalvia comprising 9 species under 2 phylum. Gastropoda included 5 species (Pila globosa, Septaria porcallana, Indoplanorbis exustus, Melanoides tuberculata and Bellamya chinensis), Bivalvia included 3 species (Anondonta californiensis, Neritina reclivata and Mercenaria campechiensis) and Oligochaeta included 1 species Nais simp/ex. Shannon diversity index demonstrated that in experiment-I, higher diversity in macro-benthos community was found in C2 compared to 1'2 and T3 (p<O.05) as well as other treatments. However. in experiment-Z C2 also showed higher species diversity than that of 1'2 (p<O.05). In experimenr-z, Menhinick's richness of macro-benthos species was found higher in C2 compared to 1'2 and T4 (P<O.02). In contrast, it was found insignificant in experiment-l. Finally, Pielou's evenness indices was found higher in T3 compared to Tl and T2 in experiment-l (p<O.05). Nevertheless, it was higher in C2 in experiment-2 than that of 1'2 and T4. In conclusion, different diets or even aquatic environment with no diets might contribute in community structure of macro-benthos species. Therefore, further studies should be conducted to go for more micro-community structure of macro-benthos.