Interspecies Variation of Element Concentrations in Marine Zooplanktons of the Western Philippine Sea
Date Issued
2016
Date
2016
Author(s)
Wu, Meng-Shan
Abstract
Zooplanktons play an important role in biogeochemical cycling of metals in marine systems. Through vertical migrations, as well as sedimentation of pellets and dead individuals, it accelerates the element transfer rate in water columns. Hence,to understand trace elemental content and interspecific heterogeneity in zooplankton can further know trace metals biogeochemical cycle in marine environment. In this study, using Ultraclean Size Fraction Techniques, zooplanktons (size in 363-500 μm, 500-1000 μm, 1000-2000 μm, 2000 μm-2 cm and >2 cm) and fish larvae were collected by vertical plankton tow at oligotrophic Western Philippine Sea. Samples were then separated into several species of zooplankton (i.e. Eucarida, Copepoda, Amphipoda, Ostracoda, and Pteropoda) under microscopes. Each sample fractions were further analyzed for their elemental (C, N, S, P and Ca) and trace metal (Fe, Zn, Cu, Ni and Cd) components. The results show distinct heterogeneity and differences in elemental(C, N) components between crustacean zooplankton and mollusc zooplankton. Due to their differences in body structure, both C and N content of Pteropoda is significantly lower than the other crustacean zooplankton. No significant difference of trace metal content (except Fe) among Copepoda, Amphipoda and Ostracoda were found by ANOVA and Scheffé''s Statistic method. However, there is significant difference between crustacean and Pterpoda. This difference may due to their physiological needs and metabolic rates, changes in Zn, Cu, and Ni between Pterpoda and crustacean zooplanktonconfirms such interspecific heterogeneity. Since zooplanktons can accumulate essential metals and actively remove excess metal, essential metals (Fe, Zn, Cu and Ni) were found with decreasing molar ratio with higher trophic level through the food web transfer. Moreover, the results indicate that biomagnification factor (BMF) of essential trace elements (Fe, Zn, Cu, and Ni) measured for zooplankton are all less than 1. On the other hand, Cd biomagnifies (BMFs > 1) from small plankton (10-63 μm and 63-153 μm) to zooplankton (153-2000 μm) and potential biodiminishes (BMFs < 1) from zooplankton to fish. In sum, trace metal concentrations in zooplankton are controlled by body size, body structure and physiological characteristics.
Subjects
zooplankton
trace element
the western Philippine Sea
Interspecies
trophic level
SDGs
Type
thesis
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