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

Abstract

Abstract. The biochemical composition of particulate organic matter (POM) produced through phytoplankton photosynthesis is important in determining food quality for planktonic consumers as well as the physiological conditions of phytoplankton. Major environmental factors controlling the biochemical composition were seasonally investigated in Gwangyang Bay, South Korea, which has only natural conditions (e.g., no artificial dams). Water samples for the biochemical compositions were obtained from three different light depths (100, 30, and 1 %) mainly at three sites in Gwangyang Bay from April 2012 to April 2013. Different biochemical classes (carbohydrates, CHO; proteins, PRT; and lipids, LIP) were extracted, and then the concentrations were determined by the optical density measured with a spectrophotometer. The highest and lowest PRT compositions among the three biochemical classes were found in April 2012 (58.0 %) and August 2012 (21.2 %), whereas the highest and lowest LIP compositions were found in August 2012 (49.0 %) and April 2012 (24.8 %), respectively. The CHO composition was recorded as high in January 2013 and remained above 25 % during the study period. The calorific contents of the food material (FM) ranged from 1.0 to 6.1 Kcal m −3 (annual average ± SD = 2.8 ± 1.1 Kcal m −3 ). Based on a Pearson's correlation coefficient analysis, a major governing factor in the biochemical composition of POM was dissolved inorganic nitrogen loading from the river input in Gwangyang Bay. In conclusion, a relatively larger amount of FM and the higher calorific contents of POM found in this study compared to other regions reflected good nutritive conditions for sustaining productive shellfish and fish populations in Gwangyang Bay. Continuous observations are needed to monitor the marine ecosystem response to potential environmental perturbations in Gwangyang Bay.

Vertical Distributions of Macromolecular Composition of Particulate Organic Matter in the Water Column of the Amundsen Sea Polynya During the Summer in 2014

“…This result is different from that reported previously in the Amundsen Sea by Kim et al () who showed the predominance of proteins (>60%). According to previous studies, variations in the quantity and biochemical composition of POM within the water column are most likely associated to biological and physical processes, such as primary production, utilization by other organisms, river discharge, and lateral advection (Fabiano et al, ; Fabiano & Pusceddu, ; Isla et al, ; Lee et al, ). In this sense, the large difference in the macromolecular compositions between this and previous studies is mainly believed to be due to a large seasonal variation in the Amundsen Sea.…”

Explicit Characterization of Spatial Heterogeneity Based on Water Quality, Sediment Contamination, and Ichthyofauna in a Riverine-to-Coastal Zone

“…Considering the highest richness and biodiversity ( H′ = 2.35, Table 2), we assert that the high productivity at this site is closely associated with the significant influx of nutrients from the river. As for the nutrients, recent biochemical research from Gwangyang Bay has reported that the influx of phosphorus and nitrogen from rivers is highly correlated with the protein compositions in the ocean [61]. The same study underlined that the high proportion of protein under the abundant nutrient condition is related to the production of phytoplankton.…”

Water Quality Improvement Shifts the Dominant Phytoplankton Group From Cryptophytes to Diatoms in a Coastal Ecosystem

“…The photic depth was calculated as 4.61/Kd (Cloern, 1987), where Kd is the light extinction coefficient, which was derived from Secchi depths (i.e., water transparency) using an equation applied to turbid waters, Kd = 1.44/Zs, where Zs is the Secchi depth measured using a Secchi disk (Holmes, 1970). The equation, Kd = 1.7/Zs was globally and locally applied to coastal waters (Poole and Atkins, 1929;Lee et al, 2017;Kang et al, 2020) but a modified coefficient, 1.44 was utilized for turbid waters (Holmes, 1970).…”