Brick Kilns and Fish: a Symbiotic Relationship? by Dr Andy Marriott

During the 1st two weeks in March Dr Andy Marriott and Dr Simon Chenery visited India to foster ties between India and UK environmental scientists. They were funded by the BGS Global team to develop future collaborative research in the growing suburban aquaculture systems. Here's Andy to share their experiences with brick kilns and fish!

Local transportation and one of the many vehicles that festoon the roads of Calcutta

Arriving in Calcutta, the city was an immediate assault on our senses. The loud cacophony of frantic horns emanating from all manner of transportation, buses, lorries, cars, motorbikes and of course the local form of transport the tut tuk’s (auto-rickshaw) sounded there confusion as each tried to jostle for position in the melee that was traffic control. India Style!!!! Construction work is everywhere with buildings sprouting up from land cleared for just this purpose. After such a long journey the developing world is really in your face! We arrived at our destination; the university guest house in its faded glory seemed like an ocean of calm in what appears to be a world of change. On our arrival we were met by Dr Sarkar our host and dear friend from the Marine Biology department at the University of Calcutta.

Team Fish (from left to right): Soumi Mitra, Dr Andy Marriott, Dr Simon Chenery, Baskhar Deb
Bhattacharya, Dr Santosh Sarkar (our host) and Dibyendu Rakshit

 This was my first trip to India and my colleague Dr Simon Chenery’s second. We visited India with the intention of developing a joint international project to investigate the biogeochemical cycling of pollutants/minerals and potential for bioaccumulation in aquacultural fish from Indian pond systems. This was our opportunity to exchange ideas and experiences from our different fields of expertise with a view to applying to UK and Indian agencies future research funding. Crucially, we were there to understand the aquaculture ponds role in supplying fish as the main source of protein/minerals for Calcutta and potential for pollutant cycling.

Brick manufacture and the chimneys which form an integral part of the process go hand in hand
with fish aquaculture with ponds forming part of the overall system

One hour south of Calcutta we approached the aquaculture pond systems formed from former brick/clay extraction sites. Here you see brick manufacture on a large scale, with brick kilns located along the main Hughli river, with their chimneys, spewing out their acrid plumes. We counted 10 such chimneys along the river banks. The areas surrounding the kilns are littered with ponds large and small, from where the removed clay are now filled with water from the river. Intertwined, these ponds are split using clay left over from the brick manufacture as makeshift walls to separate each pond. Along the makeshift walls were small reed and wood huts. We were informed that the huts were used by what we would term the local bailiff and would allow him to remain on site and to protect the pond owner’s interests. The Fish! An indication on how profitable the ponds were in the ever increasing system of aquaculture production.

Areas where Brick kilns meet fisheries aquaculture. Note the makeshift hut
on the right of the picture for the pond bailiff.

Discussions with locals by our hosts led us to a couple of likely sites. After some negotiation, we were taken to a pond where they had some fish ready netted. Surrounded by a bevy of men, women and children we collected our fish, water and sediment. Our hosts went through a questionnaire with the fisherman. Introductions complete, we were then taken to the first pond and watched as the owner walked through with his accomplice to corral fish into a corner where he could cast his net. Throughout the week we visited 9 sites/ponds and collected between 4-8 fish from each one. Now followed the task of processing all of our samples.

The pond owner proudly holding a fish surrounded by family and locals from his village.

Back at the University we prepared our samples, filtered the water and stored the sediment. Then came the arduous task of processing all those fish. Working as a team, Dr Chenery and I, and the ever helpful and enthusiastic Baskhar and two of Dr Sarkar’s PhD students Dibyendu and Soumi worked through collecting tissue samples e.g. muscle, liver and gonads combined with biological measurements such as length and weight. Scale samples were collected for aging and the removal of the fish’s ear stone or otolith. This little aragonite structure would be later used to verify the fishes age and to assess elemental concentrations incorporated within its structure using LA-and sb-ICP-MS. Trained by myself in the black art of otolith extraction Baskhar, Debindar and Soumi all became quite adept and finding these sometimes elusive little structures. Tissue samples were then vacuum sealed and stored frozen until we would transport them back with us to the UK the following morning.   Detailed analyses will follow to better understand the mineral and potential biogeochemical cycling of pollutants in these ponds which work on both an artisanal and commercial scale. 

From left to right. Dibyendu, Dr Chenery, Baskhar and Soumi process one of the fish in the labs at the marine science department

Thanks for reading about my adventures in India. Keep an eye on the blog for updates about our continuing collaboration and results

by Andy