Green Tides of the Yellow Sea: Massive Free-Floating Blooms of Ulva prolifera

Abstract

Macroalgal blooms are a form of harmful algal bloom and are generally confined within estuaries or coastal bays. The massive free-floating macroalgal blooms of Ulva prolifera in the Yellow Sea, covering thousands of square kilometers in the sea with millions of tons of biomass and causing huge economic losses, are discovered as a new ecological phenomenon. These extraordinary blooms are trans-regional in their formation, with their initial source being fouling plants growing in the Porphyra aquaculture facilities along the Jiangsu coastline. These fouling species cleaned off from the culture facilities and drifted into the sea. Driven by surface currents and winds, these floating algae are transported more than 200 km northward to the Shandong coast and proliferate sufficiently to generate a massive green tide, resulting in severe ecological and economic damage. The bloom processes are therefore a chain of complex events, where human activities, interacting with natural geohydrodynamic and climatic conditions, allow this species with distinct physiological traits to bloom. The cases indicate that we need to consider the complex biological-chemical-physical interations in coastal zone before we expand our aquaculture activity, to avoid of negative ecological consequence.