Abstract
BackgroundBoth natural and human-induced disturbances are commonly responsible for an overall decrease of the world’s seaweed. Along Japan’s coastal areas, edible seaweed production has been decreasing for decades. In this study, a production-environmental suitability model to estimate the impacts of environmental factors on seaweed production was developed. The developed model not only estimates human-induced disturbances but also quantifies the impacts of environmental factors responsible for the decline of annual seaweed production. The model estimated the temporal variation in human-induced disturbances and the effects of environmental factors (i.e., rainfall, CO2 concentrations, temperature, typhoons, solar radiation, water nutrient levels, and water quality) on edible seaweeds in Japan from 1985 to 2012.ResultsThe environmental suitability for seaweed production in Japan was about 4.6 times greater in 1992 than in 2011, meanwhile as a result of human activities, human-induced disturbances of seaweed increased at a rate of 4.9 times faster during the period of 1998–2012 than the period of 1985–1997. The ratio of decreased production to decreased environmental suitability for seaweed production in Japan increased by 15.2% during the study years, which means that seaweed production has become more sensitive to environmental disturbances, including climatic factors and human activities in 1998–2012.ConclusionsThe results are novel in demonstrating temporal variations in the level of environmental suitability to seaweed production by using a simple mathematical model. The production-environmental suitability model successfully predicted seaweed production by reflecting the 28-year temporal variation of the observed seaweed production in Japan.
Highlights
Both natural and human-induced disturbances are commonly responsible for an overall decrease of the world’s seaweed
Human-induced disturbance represents all the factors which relate to human activities and may influence the seaweed production. Rt is the value of rainfall at time t, Ct is the value of C O2 concentrations at time t, T t is the value of sea surface temperature at time t, Wt is the value of number of typhoons at time t, S t is the value of solar radiation at time t, Nt is the value of water nutrient levels at time t and Qt is the value of water quality at time t. a, b, c, d, e, f, and g represent the effects of Rt, Ct, Tt, Wt, St, Nt, and Qt relative to the seaweed production, respectively
The environmental factors analyzed in the study were selected because: the amount of solar radiation are related to seaweed communities (Bischof et al 2006); the degrees of water temperature and CO2 concentrations are positively correlated and they reflect the degrees of global warming and ocean acidification which affect seaweed communities (Pörtner 2008; Harley et al 2012); the amount of precipitation and the number of typhoons can be considered as the degree of environmental disturbances (Short and Wyllie-Echeverria 1996); water nutrient levels and water quality are related to the growth of seaweed (Msuya and Neori 2008)
Summary
Both natural and human-induced disturbances are commonly responsible for an overall decrease of the world’s seaweed. The developed model estimates human-induced disturbances and quantifies the impacts of environmental factors responsible for the decline of annual seaweed production. Chen Bot Stud (2019) 60:2 seawater and potentially being used as bio-indicators for heavy metal pollution (Johansen et al 1991; Phillips and Segar 1986; Campanella et al 2001; Serfor-Armah et al 2006) and can remove nutrients from the water column and inhibit eutrophication (Harlin and Thorne-Miller 1981) They provide an important niche, e.g., create habitat for living, eating, parenting, and hiding, for plenty of marine species, and maintain community diversity (Stachowicz et al 2008). Seaweed in general has good survival strategies, enabling the algae to withstand environmental stresses, the impacts of climatic change and human-induced disturbances on seaweeds remain poorly understood (Chan et al 2006)
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