Mounting loss of seagrass in the world's oceans, vital for the survival of endangered marine life, commercial fisheries and the fight against climate change, reveals a major crisis in coastal ecosystems, a report said.

A global study of seagrass, which can absorb planet-warming carbon dioxide, found that 29 percent of the world's known seagrass had disappeared since 1879 and the losses were accelerating.

Seagrasses are flowering plants found in shallow waters. They have been vanishing at a rate of about 110 square kilometers a year since 1980, said the study.

The study, by Australian and American scientists, found seagrass meadows were "among the most threatened ecosystems on earth" due to population growth, development, climate change and ecological degradation.

It said there were only about 177,000 square kilometers left globally.

"Seagrass meadows are negatively affected by impacts accruing from the billion or more people who live within 50 kilometers of them," said the report received by Reuters news agency yesterday.

The study said the loss of seagrass was comparable to losses in coral reefs, tropical rainforests and mangroves.

"Seagrasses are sentinels of change" and the loss of seagrass was an indicator of a deteriorating global marine ecosystem.

"Mounting seagrass loss reveals a major global environmental crisis in coastal ecosystems," it said.

It is estimated that 70 percent of all marine life in the ocean is directly dependent upon seagrass, according to US-based Seagrass Recovery.

Seagrasses are the only flowering plants that can live entirely in water. They are most closely related to lilies and are very different to seaweeds, which are algae.

They provide important ecosystem services, said the study, citing an estimated US$1.9 trillion a year in nutrient cycling, enhancement of coral reef fish productivity, habitats for thousands of fish, bird and invertebrate species and a major food source for endangered dugong and turtles.

(Shanghai Daily via Agencies July 1, 2009)