Abstract
Diving surveys using quadrats were conducted near the estuary of the
Shiribetsu River in Isoya, Suttsu, southwestern Hokkaido, Japan from 2012 to
2018.
Disjunctive distribution of the kelp Saccharina japonica var. ochotensis
was confirmed and
maintained a rich kelp forest with a high biomass. Large biennial
sporophytes of this
species occurred in deeper rocky areas, 5-10 m, and smaller annual
sporophytes were
observed in shallower areas at 0-5 m in depth. Growth of test diameter and
gonads of two
sea urchin species Mesocentrotus nudus and Strongylocentrotus
intermedius were elevated
compared to Isoyake area and factors related to this enhancement are
discussed.
