Behaviour

A recent study has revealed that penguin guano in the water can significantly alter the swimming and feeding behaviour of Antarctic krill, a keystone species in the Southern Ocean. 

The research, published in Frontiers in Marine Science, shows how the presence of chemical cues in penguin guano can trigger an escape response in krill, potentially affecting the Antarctic food chain.

This groundbreaking research documents the behaviour in several oceanic fish species spanning three oceans. It describes the first recorded instances of fish using sharks and other fish to brush and scrape against, with the goal of freeing themselves of parasites.

The study, which was led by Francesca Pancaldi, used photographic and video evidence to show how a pod of killer whales (Orcinus orca) employed a collaborative approach to target the whale sharks' pelvic area, including the claspers and pelvic fins. This strategy caused significant blood loss and allowed the killer whales access to the sharks’ lipid-rich livers, which is a highly nutritious part of the prey.

Several times a year, squaretail groupers gather at spawning aggregation sites to mate, typically around the new and full moons between December and March. The males show up several days before to establish their territories, while the females arrive a day before the new moon. Then, both groups will attempt to pair and spawn in synchrony with the moon’s cycles.

For this species, these brief encounters are their only opportunities to reproduce.

The study found that dolphins displayed the open-mouthed gesture more frequently during interactions with others than when playing alone. Even more interestingly, they tended to use this gesture when their playmate could see them, suggesting that dolphins are aware of their friends’ attention and adjust their behaviour accordingly.

Conventionally, shark behaviour has been perceived as largely instinctive and uniform across individuals. However, a team of researchers, led by Thomas M. Vignaud, have upended this notion, uncovering a spectrum of individual personalities among bull sharks frequenting feeding sites.

Researchers conducted trials using SMART drumlines in New South Wales, Australia, to catch and release sharks, particularly White Sharks. The study aimed to quantify the short-term post-release movements and the longer-term fate of these sharks.

Sharks were caught using SMART drumlines deployed about 500 meters from shore. Once captured, they were quickly secured to a research vessel, minimising potential injuries. The sharks were tagged with satellite-linked radio transmitting tags and acoustic transmitters to monitor their movements post-release.