Recently, loss of seaweed has been reported worldwide. Both natural and human-induced disturbances are commonly responsible for an overall decrease of the world’s seaweed. In Japan, the production of edible seaweed has been decreasing for decades. The objective of this study is to develop a production-environmental suitability model to estimate the impacts of environmental factors on seaweed production. The model estimated the temporal variation in the effects of environmental factors (i.e., rainfall, CO2 concentrations, temperature, typhoons, solar radiation, water nutrient levels, and water quality) and human-induced disturbances on edible seaweeds in Japan from 1985 to 2012. A Bayesian framework was adopted for parameter estimation assuming a gradual change in the human disturbance.
Results/Conclusions
I found that the environmental suitability for seaweed growth in Japan was about 4 times greater in 1992 than 2011, meanwhile as a result of human activities, areas that support seaweed growth have been increasing, resulting in the rate of distribution during the period of 1998–2012 growing 4.9 times faster than during the period of 1985–1997. The ratio of decreased production to decreased environmental suitability for seaweed growth in Japan increased by 15.2% during the study years, which means that seaweed growth has become more sensitive to environmental disturbances, including climatic factors and human activities in recent years.