Research covered the entire 2,300 kilometers of the Great Barrier Reef and found a disturbing loss at every level.
“A vibrant coral population has millions of small, baby corals, as well as many large ones – that produce large larvae,” explains Andy Dietzel from the ARC Center of Excellence for Coral Reef Studies.
“Our results show the ability to recover the great barrier reef – its resilience – is compromised compared to the past, as there are fewer children, and fewer large-breeding adults.”
Similar to old-growth forests, it is these large corals that are most concerned by marine scientists.
Losing old coral in this way can have a widespread impact on the entire reef system, as the largest colonies in the population have an effect on reproduction and the next generation of genes, while fish and other beef provide more habitat and food for life. Huh.
“Global degradation in large, old trees, for example, leads to significant habitat loss, loss of food and carbon storage,” the authors write. But where the shape of terrestrial forests has been carefully tracked over the years, trends in coral size are rarely investigated; It is traditionally about coverage.
To fill this gap, researchers shaped the systematic decline of coral reefs in the Great Barrier Reef between 1995 and 2017, the taxa from 1995 to 2017, and during that time, the reef has produced several local cyclones, four major disruptive events, and Experienced two. Large outbreak of crowns of thorns (not to mention another serious bleaching event that occurred earlier this year).
The study of the vast expanse that is the Great Barrier Reef is clearly a considerable challenge, and to estimate the size of the colonies, researchers used line-intercept length as a proxy.
This means that at the bottom a line was placed on the coral reefs to measure the greater length of various organisms.
Although not a direct measurement of coral size, line-intercept length may indicate a change in the underlying colony size, and because it has been used for such a long time, the authors state that it is “historical historical data on corals” An irreplaceable source “.
The authors found that the abundance of coral caused a rapid decline in all sizes of colony and all coral taxa. These changes were most pronounced in the northern and central regions of the Great Barrier Reef, where large-scale coral bleaching occurred recently.
Marine biologist Terry Hughes says, “We used to think that the Great Barrier Reef is protected by its sheer size,” but our results show that the world’s largest and relatively well-protected reef system is witnessing a rapid and declining .
The loss of medium and large colonies is particularly worrying, as they may possibly prevent reproduction and prevent old corals from recuperating shrinking populations. At the same time, a decrease in small coral larvae has been reported to be disproportionate in small colonies.
According to the authors of the current study, “the likelihood of recovery of old fecal corals increases the uncertainty and intensity of disturbance events.”
“The systematic decline in small colonies in areas, habitats, and taxa suggests that a decline in recruitment has eroded the recovery capacity and resilience of coral populations even further.”
And the window for recovery is closing rapidly. If we do not cut our emissions by the end of the century, studies have shown disastrous bleaching events such as those that occurred in 2016 and 2017 could very well occur on an annual basis.
“I think if we can control warming somewhere between 1.5-2 ° C [above pre-industrial levels]As per the Paris Agreement, we will still have a rock, ”Hughes told The Guardian.
“But if we’re for 3-4 ° C Due to unrestrained emissions, then we will not have an identifiable Great Barrier Reef. ”
The study was published in Proceedings of the Royal Society B.