Shawn Dsouza

Microplastic (MPs) pollution, a major consequence of industrialization and urbanisation, poses significant risks to human and animal health. MPs can accumulate in marine biota through the food chain, leading to significant adverse effects on various physiological processes. Sharks, as apex predators, may exhibit the highest accumulation of MPs. However, the impact of MPs on the reproductive systems of sharks is not well understood. To address this gap, we investigated the effect of MPs on the reproductive biology of S. laticaudus from Malvan, Maharashtra. MPs were detected in water, gastrointestinal (GI) tissue and gonadal tissue samples. The female gonads tissue exhibited significantly higher concentration of MPs compared to the gonadal tissue. However, the effects on GSI were more pronounced in males, suggesting potential physiological impacts. Understanding the risks associated with MPs can help us develop effective mitigation strategies and the organisms and the humans whom consume these species.

ABSTRACT Humans interact with wild animals through lethal and non-lethal activities. While theory predicts that these interactions should alter animal behaviour, the relative magnitude of impact is not well understood. We conducted a systematic review and meta-analysis of the past 30 years of research, focusing on changes in foraging, vigilance and movement behaviours in wild animals. We found that lethal human activities (e.g., hunting) cause significant behavioural changes, with targeted species increasing vigilance and reducing foraging in affected areas. Active non-lethal activities (e.g., tourism) elicited similar but weaker patterns, with many species showing little to no change in their behavioural responses. In contrast, passive non-lethal interactions (e.g., roads) produced highly variable responses. Overall, human-induced fear elicits responses in wild animals that broadly align with predictions from the risk allocation hypothesis. However, the magnitude and direction of animal responses depend on the type of human activity and the ecological context. The most pronounced behavioural changes occur where humans pose a direct lethal threat. Gaps in the literature, uneven data within and across species, and limited information on the history or context of interactions currently limit our ability to better predict when and why animals change their behaviour in response to humans.