• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.1
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• pp.57-69
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• 2001

The chemical, elemental and biochemical components of the suspended particulate matter (SPM) were investigated in order to quantify particulate organic matter (POM) and assess diet quality for suspension feeders in the southern coastal bay systems of Korea where the marine farming of the suspension feeders are most active, The intense field observation program was carried out seasonally in the three coastal bay systems of Chinhae, Gosung and Kangjin bays, The SPM was characterized as collective properties of organic carbon (POC), nitrogen (PON), phosphorus (PP) and more refined collective properties of protein (PPr), carbohydrate (PCHO) and chlorophyll a (Chl a) compound. Although the three coastal bays are regarded as phytoplankton based ecosystem, the SPM is not composed entirely with phytoplankton cells. Due to the shallow water depth, resuspension of bottom sediment contributes significantly to some of the regions. Therefore, concentration of SPM in the surface water did not co-vary with Chl a or PPr, PCHO. In general, temporal variation of POC, PON and Chl a contents in seawater were closely associated with phytoplankton biomass in the three coastal bays, However, PPr and PCHO contents in seawater were higher in Chinhae bay than in Gosung and Kangjin bays and Chl a PPr-N ratio was higher in Chinhae bay than in Kosung and Kangjin bays, since Chinhae bay is more eutrophicated than other bays. Average C : N ratios from regressions of POC and PON of SPM were 6.6, 6.6 and 5.0 in Chinhae, Gosung and Kangjin bays, respectively. SPM in Chinhae and Gosung bays appears to be made of largely phytoplankton cells and SPM in Kangjin bay appears to be contributed from the bacterial biomass due to the shallow water depth. N : P ratios from regressions of PON and PP of SPM were 10.8 and 14.7 in spring, and 18.2 and 24.6 in Chinhae and Gosung bays, respectively. With respect to the hypothetical Redfield molecule, phytoplankton appears to be limited by the lack of N and f in spring and summer, respectively, in the two bays, In Kangjin bay, N : P ratios from regressions of PON and PP of SPM were varied from 6.3 to 12.8 throughout the year. The low N : P ratio with resepct to the hypothetical Redfield molecule, phytoplankton growth appears to be limited by the lack of N-nutrients.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.4
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• pp.340-347
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• 2001

Seasonal variation of the elemental and biochemical composition of the suspended particulate matter (SPM) was investigated in terms of quantity and quality of diets for suspension feeders from July 1999 to August 2000 in two coastal bay systems of Gosung and Kangjin Bays in Korea. No clear patterns in the seasonal variations of SPM concentration were found in these two bay systems. The results indicated that the seasonal variation of SPM could not be considered the variation of food available to suspension-feeders. The simultaneous peaks in chlorophyll a and biochemical components in summer indicated that the quantity of the particulate organic matter primarily depended on phytoplankton productivity. However, no correlation between chlorophyll a and biochemical components [particulate protein (PPr), carbohydrate (PCHO) and lipid] were found, indicating that other processes might also contribute to the particulate organic matter in the period when the phytoplankton biomass was low. High C: Chl a and C:N, and carbohydrate peaks during the autumn to spring period suggested that resuspension of surface sediments was a probable process to supply the particulate organic matter. The food material, represented by summing up the total quantity of three biochemical components, was highest in spring with minor peaks during the period from autumn to the next spring, The food index, calculated as the ratio of food material to total SPM, did not generally exceed $6\%$ with short peaks during the year. Therefore, nutritional quality of SPM in the bays are relatively poor than in other more productive coastal waters in the world. Our results confirm that the measurement of a single chemical variable cannot describe fully the nutritive value of the seston available to suspension-feeders as previously proposed, and the biochemical composition of SPM can provide effective information on its origin and nutritive Quality.