^{An aerial view of the Tungabhadra dam in Karnataka [Image Credits: Bishnu Sarangi from Pixabay]}

Animal behaviour studies, which began in the 1970s, had a rocky start as they were viewed as a deviation from biological studies. They try to answer questions relating to why an animal's behaviour differs with different organisms and environmental factors, and the cost-benefits associated with each behaviour. Such studies help to understand not only the biology of the organism but also its ecological role. In one such study, Dr Anuradha Bhat and her group at the Indian Institute of Science Education and Research, Kolkata, have looked at the mating behaviour of zebrafish.

Understanding patterns in nature has been of interest to researchers. Some of the popular questions have been around why birds flock together, how groups of bees build their honeycombs out of perfect hexagons, how ants navigate finding the shortest path back to the nest, and the likes. Researchers across the world are trying to decipher and explain how and why such specific patterns emerge.

In a new study, an international team of researchers have found that large dams have heavily fragmented fish population across the world. Published in the Proceedings of the National Academy of Sciences, the study assessed about ten thousand species of fish worldwide affected by around 40,000 existing dams and 3,700 upcoming dams worldwide. The findings reveal that fish habitats are most disconnected in the United States, Europe, South Africa, India, and China. The proposed dams are poised to further worsen fish habitat connectivity in tropical watersheds like the Amazon, Congo, Mekong and Salween.

Delhi’s winter haze is infamous for disrupting the air, railway and road traffic. With visibility dropping to near zero on a few days, life-threatening accidents spike during this season. Animals, on the other hand, seem to have a trick up their sleeves—they use sounds or visual cues to help them ‘see’ through low-visibility conditions. But what about fish? Can they navigate through turbid waters? Indeed, says a study by researchers at two Indian Institutes of Science Education and Research (IISERs), Mohali and Kolkata. The researchers have shown, for the first time, how zebrafish find food in turbid waters.

The Vembanad lake in Alappuzha, Kerala, has developed a unique ecosystem due to different laws. The Vembanad Fish Count is a citizen science initiative that helps study the diveristy of fish in this Ramsar site.

Dams and other hydrological barriers are essential for the production of hydroelectricity and to direct water to water-deficient areas. But the presence of these structures are known to interfere with the ecology of the river, affecting the flora and fauna inhabiting it. The western ghats of India are home to many endemic fish species which are affected by these hydrological structures. Recent study from ATREE shows what can be done to ensure that the biodiversity in the Western Ghats is not lost to hydrological structures.

Sex determination in animals is an interesting topic. While the X and Y chromosomes decide the sex of an unborn baby in humans and most other mammals, external factors like temperature and humidity decide it for the crocodiles and turtles. But what decides the sex of a young zebrafish? Research now shows that a combination of internal and external factors play a role in determining sex in zebrafish. Understanding the process in depth can throw light on some of the intricate workings of nature, say the researchers.