Dinoflagellate Cysts in Coastal Sediments as Indicators of Eutrophication: A Case of Gwangyang Bay, South Sea of Korea

Abstract

Diatom densities in the surface water and dinoflagellate cysts in bottom sediments of Gwangyang Bay were studied to determine changes in the phytoplankton community structure in response to anthropogenic eutrophication and to assess the use of dinoflagellate cysts as indicators of coastal eutrophication. Our results show that, in nutrient-enriched environments, diatoms are particularly benefited from the nutrients supplied and, as a consequence, heterotrophic dinoflagellates that feed on the diatoms can be more abundant than autotrophic dinoflagellates. In short-core sediment records, a marked shift in autotrophic-heterotrophic dinoflagellate cyst compositions occurred at a depth of approximately 9-10 cm corresponding to the timing of the 1970s industrialization around Gwangyang Bay. This tentatively indicates that diatom and dinoflagellate communities here have undergone a considerable change mainly due to increased nutrient loadings from both domestic sewage effluent and industrial pollution. Our study suggests a possible potential use of dinoflagellate cysts in providing retrospective information on the long-term effects of coastal eutrophication.

The effects of different environmental factors on the biochemical composition of particulate organic matter in Gwangyang Bay, South Korea

“…during summer and winter in Gwangyang Bay (Choi et al, 1998;Baek et al, 2015). Kim et al (2009) also reported that diatom and dinoflagellate communities have experienced a considerable change because of increased nutrient loadings from both domestic sewage and industrial pollution during summer. Therefore, the seasonal change in the phytoplankton species composition and community structure could lead to a determination of the different biochemical pools on a seasonal basis.…”

Human‐induced marine ecological degradation: micropaleontological perspectives

“…However, modern foraminiferal distribution is still dominated by the opportunistic species. In addition to foraminiferal and ostracod records, dinoflagellate microfossils are also abundant in Japanese and Korean embayments, and show eutrophication-induced increases in heterotrophic species during the early to mid 20th century (Matsuoka 1995;Kim and Matsuoka 1998;Matsuoka 1999;Matsuoka and Kim 1999;Matsuoka 2001;Kim et al 2009;Matsuoka and Shin 2010;Shin et al 2010).…”

Evolution of productivity and monsoonal dynamics in the eastern Arabian Sea during the past 68ka using dinoflagellate cyst records

“…Dinoflagellates have species specific differential environmental and growth requirements, thus their cyst distribution in sediments can portray surface water conditions (Dale, 2001;Marret and Zonneveld, 2003;Zonneveld et al, 2013). Higher abundance of autotrophic species in sediments reveals stable water conditions with increased light penetration and ample nutrient supply in water column, whereas increased abundance of heterotrophic species cysts reveals availability of prey organisms and productivity changes (Zonneveld, 1997a;Marret and Zonneveld, 2003;Kim et al, 2009;Zonneveld et al, 2013). In recent surface sediments, dinoflagellate cyst distribution patterns have shown correlation with regionally varying surface water masses, physico-chemical (temperature, salinity, dissolved oxygen, nutrients) and biological (food availability, productivity) factors (Marret and Zonneveld, 2003;Zonneveld et al, 2013).…”