Water fleas see red as river Mula Mutha in Pune chokes

Mula Mutha, a river under seige

Indian rivers, lifelines for the survival of humans as well as aquatic and terrestrial plants and animals around them, are gasping for breath. The Mula Mutha river in Pune has met with the same fate. Rampant and uncontrolled urbanisation, land use changes, rapid deforestation  is taking its toll and large amounts of sewage, agricultural and pharmaceutical products as well as industrial effluents are being dumped into the river, presenting a threat to all animals large and small residing in its waters. 

The river development project proposed by the Pune Municipal Corporation to clean the Mula Mutha seems to do little to change the state of the river and is being increasingly criticised by experts and  environmentalists in the city  for being a mere cosmetic makeover that does not take into consideration the river as a living, flowing and interconnected ecosystem while the key issues related to preventing sewage and other pollutants from entering into the water have been left unaddressed.

A number of concerned citizens and organisations in Pune have come together to form the Pune River Revival campaign that has been addressing the concerns raised due to the faulty implementation of the river front development project and suggesting ecologically sustainable alternatives.

As resistance to the project continues to grow, the project activities continue to clear off patches of rich riparian forests, deposit sand on the river banks without a thought for the rich biodiversity and the teeming life forms that inhabit not only the waters, but also the banks where water and soil meet as well as the very old and rich forest ecosystems that support the once beautiful, but now bound  river.

While the effects of pollution and urbanisation can be seen on larger animals residing in and around the river, what about the smaller animals, many unseen to the naked eye that reside in the river?

A recent study titled ‘Faunistic overview of the freshwater zooplankton from the urban riverine habitats of Pune, India’ published in the Journal of Threatened Taxa authored by Vanjare, A.I., Shinde, Y.S., Padhye, S.M. evaluated the impacts of these rampant changes and pollution on zooplankton communities residing in the river waters at two sites, one along the Mula River (Ram-Mula confluence & Aundh Bridge) and the other at the Mutha River (Vitthalwadi & Garware College) within Pune city. 

Zooplankton, crucial for the health of freshwater ecosystems

The term “plankton” has its roots in the Greek language, and it literally means “drifters” – referring to the many minute organisms which are carried around by water currents. Plankton comprises of both plant and animal groups referred to as phytoplankton and zooplankton respectively, and includes microscopic organisms like bacteria, some single-celled plants as well as multi-cellular animals.

Phytoplankton form the base of the aquatic food web by functioning as  primary producers that also serve as food for both the tiny zooplankton and also for larger animals such as whales. What they lack in size, the plankton make up in numbers, which are crucial for maintaining the balance of freshwater ecosystem functioning.

Zooplankton communities respond to physical and chemical changes in the water bodies by  displaying  variations  in  their  growth,  community composition, density, diversity, and distribution and thus can be greatly useful as bioindicators to assess the water quality and health of a water body.

The study findings

• Three different groups of zooplankton namely rotifers, cladocerans and ostracods were found in the areas around the river that were sampled. Of these, rotifers  were found to be the  most  species  rich  with  47  species,  followed  by cladocerans with 15 species  and  ostracods 11 species  respectively. 
• Some of the zooplankton species were found to be sensitive to pollution due to urbanisation and could not survive polluted sites. For example, urbanisation around Ram-Mula confluence and Vitthalwadi is comparatively lower than Aundh Bridge and Garware College sites. Rotifers were reported from only three localities while cladocerans and ostracod species were observed at all the four sampling stations. Sampling stations having lesser urbanisation namely at the Ram Mula confluence and Vitthalwadi had  more  species  of  rotifers while no species were seen in the city centre. 
• Some of the common species of zooplankton were found to be in large numbers in polluted sites indicating that they had developed the capacity to cope and survive under unfavourable conditions. This can lead to the phenomenon of biotic homogenisation where species that cannot cope with pollution are unable to survive and are replaced by resilient species leading to gradual reduction in biodiversity of the area. 
• It was also found that some zooplankton such as water fleas turned red due to haemoglobin production in response to low oxygen levels in the water.

The study thus found that some zooplankton were extremely sensitive to the changes in pollution levels in the river water and responded in different ways to these changes. 

While some of the sites at present indicated better species diversity, it is extremely important to preserve the biodiversity in and around the river as threats to the river continue to grow with urbanisation and industralisation. Urgent efforts need to be made to save the river, but they should be based on realistic need assessments - informed by use of proper science and a genuine intention to bring about a change in the present condition of the river, rather than being decided by financial or political motives.

River Front Development that destroys the natural flow of the river, destroys biodiversity and turns the river into a stagnant pool of filth will be useful for no one!

Dr Avinash Vanjare is an Associate Professor in Zoology at Ahmednagar College, Ahmednagar, Maharashtra, India. He can be contacted at avinashisaac7@gmail.com

Dr Yugandhar Shinde is an Assistant Professor in Zoology at Modern College of Arts, Science and Commerce, Pune, Maharashtra, India. He can be contacted at yugandharshinde@gmail.com

Dr Sameer Padhye currently works at the Centre for Biodiversity Genomics, University of Guelph, Canada. He can be contacted at sameer.m.padhye@gmail.com.