A brand new examine from the Save Our Seas Basis D’Arros Analysis Centre (SOSF-DRC) exhibits how two shark species peacefully coexist at St Joseph Atoll, regardless of their comparable diets and behavior. Led by the present CEO of the Save Our Seas Basis (SOSF) Dr. James Lea, the analysis discovered that sicklefin lemon shark and the blacktip reef shark use the atoll in a manner that enables each to flourish.
St. Joseph Atoll, situated on the Amirantes Financial institution inside the Republic of Seychelles, is an impressive ring of coral islet that gives a critically essential setting for endangered species of sharks and rays, together with different wildlife. In March 2020, waters surrounding the St. Joseph Atoll have been declared part of a Zone 2 (conditional use) Marine Protected Space inside the nation’s bigger Marine Spatial Plan Initiative. The wealthy biodiversity that exists right here, coupled with minimal human impression and ample safety, has allowed for the marine setting and animals to thrive… just like the sharks that decision this space residence. The atoll is residence to an undisturbed inhabitants of sicklefin lemon sharks (Negaprion acutidens), which stay resident from delivery by means of sub-adulthood; the yellowish-brown shark is extensively distributed within the tropical waters of the Indo-Pacific. This area can be a significant nursery for younger blacktip reef sharks (Carcharhinus melanopterus), a species present in shallow marine waters round coral reefs within the tropical Indo-Pacific.
Each of those shark species eat bony fishes, crustaceans, molluscs, and rays, which means they need to be in direct competitors with one another for not solely prey however different assets (resembling nursery house). But, one way or the other, they aren’t. How? Properly, whereas the idea of social distancing could also be new for us, it isn’t for these sharks! Though each species use the entire atoll, there are small variations in the place they’re and when – meaning the 2 species solely overlap about 25% of the time. The analysis confirmed that even when the sharks have been on the sand flats throughout excessive tide to hunt and search shelter, their overlap was solely about 35%. The sharks then return to the deeper waters of the lagoon when the tide retreats. “What’s thrilling about this analysis is that it exhibits us how these species have tailored to exist collectively in a very confined house, basically by means of social distancing, with out out-competing one another. It’s a highly effective instance of how animals carve out particular niches, enabling them to perform collectively inside an ecosystem,” explains Lea.
This isn’t a primary for the animal kingdom, as many terrestrial animals inhabit the identical geographic ranges and assets as their competitors (e.g. lions, leopards, cheetahs, African wild canine, and so on.) however have advanced varied strategies of minimizing competitors with one another (e.g. utilizing the habitat at totally different occasions of day). The truth is, it might be fascinating to see if predator or competitor avoidance is enjoying a powerful function in structuring species communities right here! This may not solely decrease the danger of any probably aggressive encounters for the predators however preserve entry to assets, thereby offering a mechanism for coexistence.
These latest findings have been made doable because of SOSF-DRC’s community of 88 acoustic receivers positioned across the atoll, the one one of its dimension and sort within the Amirantes. In keeping with Dr. Lea, whereas the examine highlights the significance of this habitat for these two predators, it additionally raises considerations about how this delicate relationship might change due to local weather change. “Over hundreds of years, these animals have discovered methods to exist collectively underneath current environmental situations,” he says. “Given the slender tidal vary at St Joseph, we’ve got to ask ourselves what would occur if a small improve in sea degree made the sand flats habitat obtainable in any respect tides. How would this have an effect on the finely tuned ecological steadiness of the animals which have realized to thrive right here?”
Will probably be fascinating to see how the connection between these two predators- and their surrounding community- unfolds as local weather change threatens to vary the very panorama of our oceans… their residence.