Title Comparisons between East-Asian isoyake and deforestation in global kelp systems
Authers Michael H. Graham
Citation Bull. Fish. Res. Agen. No.32, 47-50, 2010
Abstract
Seaweed deforestation (isoyake) is a conspicuous phenomenon in many temperature/polar regions of the world and often results in strong ecological and economic impacts to local human communities. The study of isoyake in East Asia (especially in Japan) has a long history, however the resulting literature is generally inaccessible to researchers that do not speak Asian languages. This study integrates knowledge of the causes and consequences of isoyake in East Asia into an emerging global model of the causes of deforestation in non-Asian kelp systems. Isoyake in southern regions of East Asia result from a concurrence of increased herbivory by fish and sea urchins of sub-tropical origin with periods of decreased seaweed production due to poor oceanographic conditions. Such processes are similar to those that cause deforestation in other warm-temperate kelp systems (e.g. southern California and northern New Zealand) and may be enhanced during periods of ocean warming. Alternatively, isoyake in northern regions of East Asia result primarily from uncontrolled sea urchin grazing; inherently low kelp productivity in these regions cannot balance the high rates of kelp consumption. As such, these regions appear similar to other high latitude/low productivity kelp systems in which large enduring sea urchin barrens often exist in the absence of external controls on sea urchin abundance (e.g. predation or harvesting by humans). Therefore, the diversity of causes of isoyake in East Asian systems appears to encompass the full range of deforestation processes described for high- to low-latitude kelp systems worldwide. The unique situation in which high seaweed and herbivore diversity coincide with high variability in oceanographic processes appears may make East Asian seaweed systems more vulnerable to perturbation than other temperate kelp systems.
URI http://www.fra.affrc.go.jp/bulletin/bull/bull32/47-50.pdf
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