Kerala

Survey spots 33 odonates in Vembanad

Brown Dartlet

Brown Dartlet  

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Two-day survey by Forest Department at 14 places along a stretch of 61 km

A two-day odonate survey, organised by the Social Forestry division of the Kerala Forest and Wildlife Department, in association with Tropical Institute of Ecological Sciences, has spotted 33 species of dragonflies and damselflies in the Vembanad kole wetland.

Assistant Conservator of Forests G. Prasad told The Hindu that the survey showed considerable changes in the diversity of dragonflies and damselflies in tune with the ecological changes in the vicinity of the Vembanad wetlands.

The survey, conducted at 14 places along a stretch of 61 km on the banks of the Vembanad lake, concluded on Sunday.

Of the 33 species spotted, the Brown Dartlets (Kariyila-thumbi) and Coastal Gliders (Pozhi-thumbi) found in Vaikom were rare species, Mr. Prasad said.

However, the Ditch Jewel (Changathi-thumbi) was a common species spotted at all 14 places. Odonates are indicators of fresh or polluted waters. Water contamination can easily be understood from the presence or absence of some odonate species.

Considering the importance of biological indicators and increased discussions in the field of wetland conservation, the odonate fauna needs to be protected in wetland conservation efforts, says Mr. Prasad.

Warning signal

The spotting of Ditch Jewel in almost all places was an indication of the alarming degradation of the wetland system.

The Blue Grass Dart (Naattu-poothali), Common Picture Wing (Salabha-thumbi), Pied Paddy Skimmer (Swami-thumbi), and Ruddy Marsh (Valayal-thumbi), that usually keep marshy land its main habitat too were spotted in large numbers during the survey.

According to Mr. Prasad, the dragonflies and damselflies of Vembanad region need to be observed in a new perspective, especially against the backdrop of the post-flood scenario.

Kuttanad is closely related to the Vembanad lake. Many forest-dwelling odonates of the high ranges of Idukki, Pathanamthitta and Ernakulam districts were washed down with their larvae and eggs during the last two floods to the downstream reaches and ultimately to Kuttanad.

A proper understanding is required about the washing out of large number of odonates from their upland habitats, due to the recurrent heavy floods.

Their population in natural forests of higher elevation leads to their being washed down to the feeder rivers of Vembanad lake. This makes their actual natural population to dwindle due to the repeated wash out processes.

Extinction possible

This may even cause total extinction of some genera including odonates, fishes, and amphibians. A baseline study on this aspect is inevitable for conservative efforts of Wetland micro fauna.

In future, school students may be trained to raise small pools in their schools or home premises or in housing colonies or even in panchayat lands to harbour Odonates, says Mr .Prasad.

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Printable version | Jan 27, 2020 5:22:58 AM | https://www.thehindu.com/news/national/kerala/survey-spots-33-odonates-in-vembanad/article30488037.ece

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