Press Release

July 9, 2015

Fisheries Research Agency

Worldwide experiment shows that amphipods, snails and other small animals maintain healthy eelgrass meadows

  • International research project for conducting global-scale ecological experiment has demonstrated that loss of small animal diversity has large effect on the health of seagrass ecosystems, according to new results from a coordinated experiment spanning the northern hemisphere.
  • It is expected that ecosystem management of seagrass meadows, including small vertebrates, will contribute to a new aspect of the conservation/restoration plans for eelgrass ecosystems.

Eelgrass (Zostera marina) is a perennial flowering sea plant forming valuable seagrass meadows with various functions, such as improving water quality by absorbing nutrients, fixing carbon dioxides like forests and fish nurseries. However, seagrass meadows are declining worldwide.

To examine conservation measures for eelgrass meadows, National Institute of Fisheries and Environment of Inland Sea (FEIS), Fisheries Research Agency has participated in an international research group, called Zostera Experimental Network, with the Field Science Center for the Northern Biosphere’s Akkeshi Marine Station of Hokkaido University. This group conducted the unprecedented experiment simultaneously at 15 sites across the Northern Hemisphere, covering almost the entire distribution range of eelgrass. The experiment revealed that small invertebrates such as amphipods and snails eat algae that cover eelgrass, promoting the growth and survival of eelgrass, and the invertebrate biodiversity had stronger effect on productivity than did temperature and experimental fertilization.

The invertebrates in seagrass meadows are also important as food for fish, suggesting that eelgrass meadows not inhabited by small invertebrates have significantly reduced ecosystem functions. These findings are expected to greatly contribute to the conservation of seagrass meadows.

The study was published in the July 2015 edition of the international scientific journal Ecology Letters (its electronic edition was released in advance on May 17) and supported by grants from the National Science Foundation (USA) and JSPS KAKENHI (2012-2015, no. 24405012).

Fig. An image of a healthy eelgrass meadows inhabited by diverse small invertebrates (left)
declining ecosystem functionings due to a decrease in the diversity of small invertebrates (right)