DEPARTMENT OF Zoology

Executive Summary of Final Report

1908-MRP/14-15/KLMG023/UGCSWRO

Summary of the findings

Aquatic insect diversity of 16 stream sites of SE Western Ghats were studied and water parameters such as pH, Dissolved Oxygen and Temperature were recorded.

The main objective of the study was identification of major taxa in different sites, analysis of the diversity index and to evaluate the influence of water parameters on the diversity and species composition

Samples were collected from 18 sites from streams of the following rivers

Meenachil (Vellani, Chamapara, Marumala Waterfall site no 1.1, 1.2 & 1.3) , Kabini (Makkiyad 2.1, Wayanad) , Thejaswani ((Near Chittarickal,   Payyannur 3.1), Thejaswani River (Maloth Near Konnakkad,   Kasargod 4.1),  Downstream Kakkayam Dam 5.1, Veliyathodu (Erupoolumkad near Kuravilangad 6.1),  Kallar river (near Vattakayam, Ponmudi Road, Thiruvananthapuram 7.1), Muthirappuzhayar River(Attukkad waterfall road, Pallivasal 8.1), Thodupuzha  (Thommankuthu 9.1), Manimala (Vellapara waterfalls11.1), Pampa (stream Perumthenaruvi Hilltop 12.1),  Upper Chittar (Irunooti meenmooti Waterfalls, Kummil 13.1) and Kurianad (Kuravilangad 14.1),  Moorkankavu river 15.1, Aruvikuzhi Waterfall 16.1 (Pannagam stream Oravakkal)

780 specimens belonging to 39 Genera coming under 29 Families and 8 Orders were identified. Ephemeroptera constitutes the highest percentage of sampled specimens (39.87%) followed by Trichoptera (33.33%), Plecoptera (10.13%), Odonata (8.97%), Coleoptera (3.08%), Hemiptera/Heteroptera (4.10%), Diptera (0.38%) and Lepidoptera (0.13%).

Perumthenaruvi of  Pampa stream recorded highest ‘Effective number of Species’  with a value of 9.121 followed by Irunooti meenmooti Waterfalls, Upper Chittar Kummil with a value of 9.032

The average value of ‘Effective numbers of Species’ were found to be 5.716 and Eight Sites (Vellani  Site No 1.1, Marumala Site No 1.3, Chittarickal Site No 3.1, Ponmudi Site No 7.1, Thekkemala site No 10.1, Vellapara Site No 11.1, Perumthenaruvi Site No 12.1 and Upper Chittar Site No 13.1 recorded an Index value of  9.034 whereas Aruvikuzhi Site No 16.1 recorded the Lowest value of 2.904

Specimens belonging to the family Hydropsychidae (216) are the most abundant Taxa recorded from all the sites, followed by Heptageniidae (196).

Margalef’s, Shannon-Wiener, and Pielou indices are used to gain insight into relative abundance of taxa and their relative evenness. Although these indices indicate the comparison of diversity, richness and distribution between streams, however they are not actual measure of diversity but merely Indexes for comparison. Out of the eighteen sites Perumthenaruvi 12.1 shows highest relative species diversity index while site Aruvikuzhi16.1 scores the lowest.

Family Biotic Index of 18 sites reveals ‘Excellent’ water quality in 5 sites with Chamapara 1.2 on top and Kakkayam indicating ‘Fair” water quality. Lower values of Family Biotic Index indicates higher diversity

In terms of Percent EPT Pallivasal exhibits highest percentage of EPT taxa compared to that of Kakkayam with only 12.5 %. However the %EPT alone cannot confirm good or poor stream health due to the fact that the observations in many sites suggests accumulation of  Ephemeropteran taxa or Trichopteran (Hydropsychidae family) thereby becoming dominant taxa with high tolerance to environmental variables

Correlation between inverse of FBI (1/FBI) and pH shows a value of +0.35246 which is a significant positive correlation (in the pH range of 6.23 and 7.42)

Correlation between 1/FBI and Dissolved Oxygen shows a value of +0.14031, which is a moderately positive correlation

Correlation between 1/FBI and Temperature shows a value of -0.314096, which is a significant negative correlation. Family Biotic Index values are inversely related to health of a habitat

The data analyzed using PAST for Principal Coordinates Analysis shows clustering of most of the taxa except for few such as Acroneuria sp, Thalerosphyrus sp, and Hydropsyche sp. These species also happen to be most dominant species at various sites and also seem to tolerate relatively unfavorable environmental parameters such as low DO, low pH  and higher temperature values.