World of Underwater Forest

Sargassum horneri (Kumamoto Pref)
Can you imagine the wold of underwater forest?

Underwater forest, known as "Moba" in Japanese, is the highly dense community of seaweed (including seagrass), and is recognized as one of the most productive ecosystem in the coastal area. Seaweed forests (or bed) occur worldwide. In Japan, we can see various types of seaweed forest including kelp (Laminaliales) and Sargassum with more than 1500 species of seaweeds. Seaweed forest provide three-dimensional habitat for marine organisms, and support its biodiversity.
Seagrass bed (Thalassia hemprichii)
These communities are strongly influenced by a variety of eco-environmental factors such as light, temperature, nutrient, wave motion, grazer, and etc. More importantly, there is concern that continued changes in the coastal environment, caused by climate change and other human activity, may drive the degradation this habitat and result in the loss of biodiversity. Indeed, the area of Japanese seaweed / seagrass communities decreased by around 40% in the past 30 years. Many surveys suggest that the species composition of seaweed has also changed in throughout Japan. In particular, subtropical seaweeds have been observed in the transitional area between temperate and subtropical regions of southern Japan. To conserve the biodiversity of coastal ecosystem, further study of seaweed ecology and diversity is now strongly required.


Saccharina japonica


Eggs of squid in Sargassum bed