Introduction
Diatoms are a successful and ubiquitous phytoplankton group with over
200,000 species. They range in size from µms to mms and exist either as
single cells or as chains of connected cells (Kooistra, et al. 2007).
These silica-depositing microalgae have been abundant for more than 180
million years (Falkowski, et al. 2004); they contribute 40% of the
total oceanic primary production and ~20% of global
primary production (Field, et al. 1998), and annual diatom
photosynthesis reportedly generates approximately as much organic carbon
as all rainforests combined (Field, Behrenfeld, Randerson and Falkowski
1998, Nelson, et al. 1995). Diatoms in coastal waters support the most
productive fisheries, and in the open ocean, they sink rapidly from the
surface to become food for deep-water organisms (Sarthou, et al. 2005).
Thus, diatoms are crucial contributors to the global carbon cycle and
have even been considered as a potential solution for reducing
atmospheric CO2 levels (Denman 2008). Given their
ubiquitous nature, diatoms are logical subjects for researchers
interested in global ecological trends such as climate change, as
foreseen in the concept that “everything is everywhere, but the
environment selects” ((Finlay 2002). Changes in diatom community
diversity can be considered to be indicative of adaptation occurring in
response to selective pressures.
The Korean Peninsula is surrounded by the Yellow Sea (YS), the Southern
Sea (SS; also known as Korean coastal waters connected to the East China
Sea), and the East Sea (ES, or the Sea of Japan), each with its
distinguishing characteristics. The YS, located between mainland China
and the Korean Peninsula, is a shallow (generally < 100 m),
post-glacially submerged, epicontinental sea with one of the largest
continental shelves in the world (Wang, et al. 2003). The SS is
subjected to Kuroshio currents and receives outflows from the Changjiang
River, which is among the world’s largest rivers (Ichikawa and Beardsley
2002). Also bordering Japan and Russia, the ES is a typical,
mid-latitude, marginal sea, approximately the size of the western
Mediterranean and is somewhat unusual in exhibiting characteristics
typical of both closed basins and oceans. Similarities to the former are
due to its sill depths of < 150 m which limits seawater
exchange with the North Pacific Ocean. ES also contains oceanic deep
basins (> 3000 m), large (> 15℃) seasonal
variations in sea surface temperatures, and highly active biological
processes and exhibits a sub-arctic polar front between its sub-polar
and sub-tropical seas (Kim, et al. 2001).
Diatom communities tend to dominate in well-mixed coastal and upwelling
regions, as well as along sea-ice edges where sufficient light,
inorganic nitrogen, phosphorus, silicon, and trace elements are
available to sustain their growth (Morel and Price 2003). Therefore, the
purpose of the present study is to investigate the diversity and
distribution of diatom communities in the coastal areas of South Korea
through a winter survey of 114 sampling sites and to clarify links to
sea characteristics using diatom community cluster analysis.