All About Sargassum
What impact could this have on turtles?
Sea turtles face a bewildering range of human induced threats, from hunting for flesh and eggs, bycatch in drifting fishing nets, wounding from power boats as they approach coasts, habitat destruction in feeding grounds and damage to traditional nesting beaches. It is a miracle that any turtle has survived to maturity and egg laying, but now there is another threat. Removing this threat can go some way to helping turtles back on the road to recovering former numbers. Turtles face a terrible situation as Sargassum drifts into new areas, invading their breeding areas and disrupting crucial parts of their life cycle.
We’ve all seen those iconic and emotionally stirring pictures of beautiful turtles swallowing plastic carrier bags, choking, getting trapped in fishing nets, but the truth is that these turtles have been lucky enough to reach adulthood. Most turtles do not get that far. Mortality of hatchlings is high, it always has been and always will be: the videos of plucky, tiny, baby turtles emerging from their beach-buried eggs serve to highlight just how vulnerable these wonderful creatures are in their early days. It’s been estimated that only one in a thousand turtle eggs hatch and survive long enough (about a decade) to reach reproductive maturity1.
Turtles and Sargassum
In the past, small amounts of seaweeds like Sargassum washing up on the beaches may have helped turtles: preventing beach erosion, providing nutrients and normal ‘ecosystem’ functions. Offshore, it will have also helped by providing safe shelter for juveniles. Now, the balance has shifted dramatically, and Sargassum is now out of control and represents perhaps the biggest threat to their survival.
Sargassum inundates the coast and forms a huge physical barrier preventing nesting234. Forced into searching out alternative nesting sites and with increased competition for space, existing nests become disturbed leading to the destruction of entire clutches of eggs. Those turtles lucky enough to get their eggs into the sand in an accessible location often find the beaches subsequently become covered over with Sargassum, preventing hatching.
They are also exposed to arsenic and hydrogen sulphide as the seaweed rots5.
Worse, the seaweed may even alter the thermal conditions in the sand (early data suggests a cooling effect) leading to the production of more male hatchlings2. All in all, Sargassum is a threat to turtles on a scale that makes humanity’s propensity for turtle soup, creating plastic pollution and fishing bycatch look like a mild irritant. Populations already on their knees are likely to be pushed over the edge and may not ever recover.
Reducing Sargassum Beaching
By intercepting the Sargassum offshore and preventing the catastrophic and overwhelming inundation of the coastal regions, we hope to give turtles the chance they need to recover their numbers. Whilst we are in the business of Carbon Dioxide Removal, we can play a vital part in protecting these endangered and vulnerable populations, and we will do our utmost to make this happen.
We are often asked about whether our AlgaRay’s will inadvertently catch turtles, which is something we have researched and designed around a lot.
Our speed of movement is low… about 1.5-2 miles per hour, and we’ll be on the surface where the seaweed is. If they were there, even the smallest of turtles would be able to outrun the AlgaRay easily.
In the incredibly unlikely event that a smaller turtle did somehow become trapped within an AlgaRay, our sinking operation takes just a few minutes. They would be released at a depth of 200 metres along with the seaweed, which sounds terrible to us, but the majority turtles are more than happy down to 290 metres, and some even beyond 1000 metres6.
The seaweed will sink and the turtle will be free to swim away.
All this thinking about turtles has been useful though: we’ve come across a technology that we can add on to our AlgaRay that may be able to detect turtles in the waters we are active in. Although it’s not directly relevant to what we are doing and the data has limited (actually none) commercial value, it could provide vital data to turtle ecologists and conservationists so we’ll do our best to include it; at the end of the day, what’s the point in trying to save the planet for humanity if the best things on it don’t make it alongside us?
Survival from Egg to Adulthood in a Declining Population of Loggerhead Turtles, Caretta caretta (Herpetologica) ↩
Sargassum accumulation may spell trouble for nesting sea turtles (Frontiers in Ecology and the Environment) ↩ ↩2
The Atlantic Sargassum invasion impedes beach access for nesting sea turtles (Climate Change Ecology) ↩
Beached Sargassum alters sand thermal environments: Implications for incubating sea turtle eggs (Journal of Experimental Marine Biology and Ecology) ↩
Covid-19 and Sargassum blooms: impacts and social issues in a mass tourism destination (Mexican Caribbean) (Maritime Studies) ↩