This study tested the hypothesis that, in the Sea of Japan off southwestern Hokkaido, recruitment and production of Saccharina japonica and Saccharina religiosa are restricted by low nutrient concentration.
Site Selection Criteria:
The experiment was conducted in two small ports, with each nutrient-enhanced and natural site being about 0.5ha at a depth of 1.4m. The nutrient-enhanced and natural sites faced west and were separated by 0.2 km. Neither site was influenced by freshwater or domestic waste inflows. The bottom substrata at each site consisted of rocks (on which the growth of crustose coralline algae was predominant) surrounded on all sides by sand.
Cause Of Decline:
Large perennial brown algae belonging to the orders Laminariales (kelp) and Fucales (fucoids) dominate many intertidal and subtidal rocky shore environments in temperate and subarctic regions, and provide important habitats and nurseries to a wide range of species. Phase shifts between kelp forest and barren states are affected by the intensity of sea urchin herbivory which, in turn, is regulated by the abundance of vertebrate predators, disease, recruitment and climate change effects. In the Macrocystis pyrifera forests off California, low nutrient concentration during summer, coupled with above-average seawater temperatures, has resulted in canopy deterioration and failed recruitment of subtidal kelp species. In Japan, phase-shift alternations of kelp, between forest and barren states, have also been reported.
, Vol. 26., Journal of Applied Phycologyhttps://doi.org/10.1007/s10811-013-0196-z