我们都看到了藻类如何在我们的家庭水族馆中扼杀珊瑚,而在野外也是如此。但是,野生藻类的藻类放牧的鱼正在做各种零件,以使藻类水平保持在天然礁石上,以使珊瑚产卵定居并生长以建造繁荣的礁石。
Scientists studied severely damaged reefs in the Caribbean with large losses of live coral and noted they soon become overgrown with algae not allowing for coral restoration to naturally take place. But reefs surrounding the South Pacific island of Moorea in French Polynesia has experienced large losses of live coral in the past and continue to bounce back, returning to a thriving coral reef.
“We wanted to know why Moorea’s reefs seem to act differently than other reefs,” says Tom Adam, postdoctoral fellow at the University of California, Santa Barbara. “Specifically, we wanted to know what ecological factors might be responsible for the dramatic patterns of recovery observed in Moorea.”
The Moorea Coral Reef Long-Term Ecological Research (MCR LTER) project examined this and Adam was a part of the research and first author of a paper published in the期刊PLOS ONE. The research team was surprised by its findings. The biomass of herbivores on the reef—fish and other animals that eat plants like algae—increased dramatically following the loss of live coral.
“What was surprising to us was that the numbers of these species also increased dramatically,” says Andrew Brooks, co-author, deputy program director of MCR LTER, and associate project scientist with MSI. “We were not simply seeing a case of bigger, fatter fishes—we were seeing many more parrotfishes and surgeonfishes, all of whom happened to be bigger and fatter. We wanted to know where these new fishes were coming from.”
Predatory crown-of-thorn sea stars have devastated coral reefs before but the team found not all the Moorea reefs were affected the same by the sea star outbreak. The crown-of-thorns sea stars did eat most of the live coral on the barrier reef (the reef that separates the shallow lagoons from the deeper ocean). Despite this, the team found that natural disasters like cyclones and natural predation by the crown-of-thorns had little impact on the corals growing on the fringing reef that grows against the island.
“We discovered that these fringing reefs act as a nursery ground for baby fishes, most notably herbivorous fishes,” says Brooks. “With more food available in the form of algae, the survivorship of these baby parrotfishes and surgeonfishes increased, providing more individuals to help control the algae on the fore reef.
“In effect, the large numbers of parrotfishes and surgeonfishes are acting like thousands of fishy lawnmowers, keeping the algae cropped down to levels low enough that there is still space for new baby corals to settle onto the reef and begin to grow.”
为什么加勒比海被藻类和垂死的礁石困扰?该研究表明,过度捕获会导致缺乏健康的鹦鹉鱼和外科医生,从而使藻类猖ramp。通过建立海洋保护区(MPA),过度捕捞和保护鱼类确实有助于创造大量的成年鱼类,但保护托儿所地区对鱼类种群和礁石的整体健康很重要。
[通过未来]