Research note: Identity of the Qingdao algal bloom

Abstract

In early July 2008, news agencies worldwide reported on a vast algal bloom that was threatening the upcoming Olympic sailing events in Qingdao, China. The identity of the culpable alga, however, remained undiscussed. We have identified the alga that caused the bloom by means of morphological and molecular data, including sequence data of the plastid encoded large subunit ribulose 1,5-bisphosphate carboxylase gene (rbcL) and the nuclear encoded rDNA internal transcribed spacer (ITS) region. The bloom-forming alga falls within the morphological limits of the green seaweed Ulva prolifera O.F. Müller ('Enteromorpha prolifera (O.F. Müller) J. Agardh') but our phylogenetic analyses show that it forms a clade with representatives of the Ulva linza-procera-prolifera (LPP) complex. The Chinese rbcL sequences are identical to those of specimens collected from Japan, New Zealand, Finland and Portugal, suggesting that the taxon is widely distributed. rDNA ITS sequences showed a close affinity with Japanese isolates of the species complex. The Qingdao bloom is a typical illustration of a green tide, which occurs increasingly along several coasts worldwide.

Re-evaluation of green tide-forming species in the Yellow Sea

“…Leliaert et al (2009) concluded that the species from 2008 Qingdao was part of the Ulva linza-proceraprolifera (LPP) complex, whereas Wang et al (2010) concluded that the alga was U. prolifera. Zhang et al (2011) reported that the blooming species forming the floating mats in the YS in 2008 and 2009 was U. prolifera based on a 5S rDNA spacer sequence analysis.…”

Inter- and intra-annual patterns of Ulva prolifera green tides in the Yellow Sea during 2007–2009, their origin and relationship to the expansion of coastal seaweed aquaculture in China

“…While so- The fifth putative cause of the blooms has been a general attribution to eutrophication (e.g., Leliaert et al, 2009) or enhanced nutrient supply from increased rainfall . Enteromorpha (Ulva) species have been shown to have a high nitrogen requirement for optimal growth (Poole and Raven, 1997).…”

“…Since that time, various news reports and scientific articles have described the event, discussed the causes, evaluated the consequences and studied the biology of U. prolifera. Fu et al (2008), , Leliaert et al (2009), Li et al (2009), Liu et al (2010a,b) and Pang et al (2010) studied aspects of its biology and genetics. The scale of the bloom and its movement was described using satellite tracking methods by Hu and He (2008), Hu (2009), , Shi and Wang (2009) and Hu et al (2010).…”

“…doi:10.1016/j.marpolbul.2011.03.040 line citing the high biomass of waste U. prolifera that grows on the Porphyra aquaculture rafts as the source biomass for the bloom. Some scientists attributed the source of the 2008 U. prolifera bloom to the Yangtze River (Xu et al, 2009) and the eutrophic condition of the Yellow Sea (Leliaert et al, 2009) which is influenced by outflows from the Yangtze River (e.g., Wang et al, 2003). Zhang et al (2010) suggested somatic cells in marine sediments provided a propagule bank for U. prolifera.…”

Phylogeny and Molecular Evolution of the Green Algae

“…The green seaweeds (Ulvophyceae) abound in coastal habitats. Some green seaweeds (mainly Ulva) can form extensive, free-floating coastal blooms, called 'green tides' (Leliaert et al, 2009c); others, like Caulerpa and Codium are notorious for their invasive nature (Meinesz & Hesse, 1991;Jousson et al, 2000;Lapointe et al, 2005). The prasinophytes are planktonic green algae that occur mainly in oceanic environments and are especially abundant in more eutrophic, near-shore waters, where they can form monospecific blooms (O'Kelly et al, 2003;.…”