Remote sensing oceanography of a harmful algal bloom off the coast of southeastern Vietnam

Abstract

[1] Harmful algal blooms (HABs) in the southeastern Vietnamese coastal waters have caused large economic losses in aquacultured and wild fisheries in recent years; however, there have been few oceanographic studies on these HAB events. The present study reports an extensive HAB off southeastern Vietnamese waters during late June to July 2002 with in situ observations and analyzes the oceanographic conditions using satellite remote sensing data. The HAB had high chlorophyll a (Chl a) concentrations (up to 4.5 mg m À3 ) occurring $200 km off the coast and $200 km northeast of the Mekong River mouth for a period of $6 weeks. The bloom was dominated by the harmful algae haptophyte Phaeocystis cf. globosa and caused a very significant mortality of aquacultured fish and other marine life. In the same period, sea surface temperature (SST) imagery showed a cold water plume extending from the coast to the open sea, and QuikScat data showed strong southwesterly winds blowing parallel to the coastline. This study indicated that the HAB was induced and supported by offshore upwelling that brings nutrients from the deep ocean to the surface and from coastal water to offshore water and that the upwelling was driven by strong wind through Ekman transport when winds were parallel to the coastline. This study demonstrated the possibility of utilizing a combination of satellite data of Chl a, SST, and wind velocity together with coastal bathymetric information and in situ observations to give a better understanding of the biological oceanography of HABs. INDEX TERMS: 4855

Temperature effects on growth, colony development and carbon partitioning in three Phaeocystis species

“…strains of P. globosa derived from the South China Sea and the Vietnam coast; Tang et al 2004). P. pouchetii AJ01 also did not form colonies at all tested temperatures (confirming the results of Malin et al 1998), suggesting that the role of temperature is minor in controlling the development of colonies.…”

“…They have both an ecological impact on the local food web and a negative economic influence on tourism. Dense blooms have also been observed off the coasts of southeast China , Vietnam (Tang et al 2004), and Norway (Larsen et al 2004). The clones isolated from Chinese and Norwegian waters have hemolytic properties as well (Shen et al 2004, van Rijssel et al 2007.…”

Winter phytoplankton bloom induced by subsurface upwelling and mixed layer entrainment southwest of Luzon Strait

“…The study area is located in a relatively oligotrophic tropical-subtropical ocean (Tang et al, 1999(Tang et al, , 2004b. Averaged winter SST of about 24.3°C promotes the growth of phytoplankton (Peñaflor et al, 2007), and monthly mean photosynthetically active radiation (PAR) observed in winter at the study area is high (Chen et al, 2006).…”

“…Though the SCS is a relatively oligotrophic tropical-subtropical ocean (Tang et al, 1999(Tang et al, , 2004b, winter phytoplankton blooms occur in the vicinity of Luzon Strait in certain years (Tang et al, 1999;Chen et al, 2006;Peñaflor et al, 2007). Tang et al (1999) first reported this phenomenon appeared in the winters of 1981, 1982 and 1984 using Coastal Zone Color Scan (CZCS) data.…”

Effects of elevated CO2 on phytoplankton community biomass and species composition during a spring Phaeocystis spp. bloom in the western English Channel

“…Mass fish mortalities have been linked to Phaeocystis spp. blooms in the Irish Sea (Rogers and Lockwood, 2009) and south-eastern Vietnamese coastal waters (Tang et al, 2004). The mass transport and sedimentation of a P. globosa bloom in 2001 in the Oosterschelde estuary (North Sea) caused anoxic conditions that led to the mass mortality of 10 million kg of Mytilus edulis with a market value of 15 to 20 million euro (Peperzak and Poelman, 2008).…”