New study provides global analysis of seagrass extinction risk

ScienceDaily (May 25, 2011) — A team of 21 researchers from 11 nations, including professor Robert “JJ” Orth of the Virginia Institute of Marine Science, has completed the first-ever study of the risk of extinction for individual seagrass species around the world. The 4-year study, requested by the International Union for the Conservation of Nature (IUCN), shows that 10 of the 72 known seagrass species (14%) are at an elevated risk of extinction, while 3 species qualify as endangered. The authors caution that loss of seagrass species and seagrass biodiversity will seriously impact marine ecosystems and the human populations that depend on the resources and ecosystem services that seagrasses provide. A 1997 study placed the value of those services at US$34,000 per hectare per year. Seagrasses offer critical habitat for aquatic life, clear the water by reducing wave action, absorb excess nutrients, and reduce shoreline erosion. The study, in the online issue of Biological Conservation, determines the likelihood of extinction for each of the world’s 72 species of seagrass using the categories and criteria of the IUCN’s Red List of Threatened Species. … The researchers listed 48 species (67%) in the “Least Concern” category, including eelgrass (Zostera marina), the most common seagrass in lower Chesapeake Bay. Orth notes, however, that most of these species — including eelgrass — are declining in their area of coverage. (Data from VIMS’ annual aerial survey shows that eelgrass is absent from one-half of its former range and continues to decline in the areas where it remains). …