Environmental News from India:
- Indian scientists are tapping into fish ear bones (otoliths) from archaeological records and present-day fishes to mine climate data.
- Fish otoliths are calcium carbonate structures in the heads of bony fishes that help them with hearing and balance. These timekeeping structures grow throughout a fish’s life, recording growth patterns in sync with changes in the water’s condition.
- High-resolution data points from otoliths, such as sea surface temperature over a period of time, can strengthen climate models.
In 2018, fishery scientist Ashim Nath, with the help of local fisher community, netted the hilsa fish along upstream and downstream locations on the Hooghly river on India’s east coast. A year earlier, on the other side of the country in the Gulf of Kutch, in west India, another set of researchers, aided by the fisher community, caught catfish (Arius sona).
The focus of their aquatic endeavours spanning east-west coasts was on otoliths or fish ear stones – pearly white, pea-sized hard structures found inside the heads of bony fishes that help them with hearing and balance. These calcium carbonate structures grow over time throughout a fish’s life, similar to the way tree rings grow. And just as tree rings are packed with information about trees and the environment, otoliths record growth patterns in sync with changes in the water’s condition. For example, otoliths show seasonal changes in their environment as alternating opaque and translucent rings.
Researchers in India are listening in to these clues by tapping into otoliths from live-caught fish and dead fish in fossil records, to mine and analyse a wealth of growth data that advances paleoclimate science and can be plugged into climate models. Combined with other sources of data, otolith-based data also informs current practices in fisheries and their management amid human-caused pressures.
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