Do risk-prone behaviours compromise reproduction and increase vulnerability of fish aggregations exposed to fishing?

Human disturbances can prompt natural anti-predator behaviours in animals, affecting how energy is traded off between immediate survival and reproduction. In our study of male squaretail groupers (Plectropomus areolatus) in India's Lakshadweep archipelago, we investigated the impact of fishing pressure on anti-predatory responses and reproductive behaviours by comparing a fished and unfished spawning aggregation site and tracking responses over time at the fished site. Using observational sampling and predator exposure experiments, we analysed fear responses (flight initiation distance, return time), as well as time spent in vigilance, courtship and territorial defence. Unpaired males at fished sites were twice as likely to flee from simulated predators and took longer to return to mating territories. In contrast, paired males at both sites took greater risks during courtship, fleeing later than unpaired males, but returned earlier at the unfished site compared with the fished site. Our findings suggest that high fishing pressure reduces reproductive opportunities by increasing vigilance and compromising territorial defence, potentially affecting mate selection cues. Altered behavioural trade-offs may mitigate short-term capture risk but endanger long-term population survival through altered reproductive investment. Human extractive practices targeting animal reproductive aggregations can have disruptive effects beyond direct removal, influencing animal behaviours crucial for population survival.

Biofilm-forming bacteria associated with corals secrete melanin with UV-absorption properties.

Corals are colonized by a plethora of microorganisms, and their diversity plays a significant role in the health and resilience of corals when they face oxidative stress leading to bleaching. In the current study, we examined 238 bacteria isolated from five different coral species (Acropora hyacinthus, Pocillopora damicornis, Podabacea crustacea, Porites lobata, and Pavona venosa) collected from the coral reef ecosystems of Kavaratti, Lakshadweep Islands, India. We found that bacteria such as Psychrobacter sp., Halomonas sp., Kushneria sp., Staphylococcus sp., Bacillus sp., Brachybacterium sp., Citrobacter sp., and Salinicola sp. were commonly present in the corals. On the other hand, Qipengyuania sp., Faucicola sp., Marihabitans sp., Azomonas sp., Atlantibacter sp., Cedecea sp., Krasalinikoviella sp., and Aidingimonas sp. were not previously reported from the corals. Among the bacterial isolates, a significant number showed high levels of biofilm formation (118), UV absorption (119), and melanin production (127). Considering these properties, we have identified a combination of seven bacteria from the genera Halomonas sp., Psychrobacter sp., Krasalinikoviella sp., and Micrococcus sp. as a potential probiotic consortium for protecting corals from oxidative stress. Overall, this study provides valuable insights into the coral microbiome and opens up possibilities for microbiome-based interventions to protect these crucial ecosystems in the face of global environmental challenges.