Decomposition dynamics of three macroalgal species inhabiting Gouqi Island seaweed bed

LIU Zhangbin; WANG Kai; CHEN Yifan; LI Xunmeng; ZHANG Shouyu

doi:10.13984/j.cnki.cn37-1141.2023.06.011

Abstract：It is of great significance to study the decomposition process and nutrient dynamics of mac-roalgae for understanding the material cycling process in the seaweed bed ecosystem.Through outdoor decomposition simulation experiment,the changes of nutrient components in the decomposition process of the dominant species Sar gassum horneri,Grateloupia livida and Ulva lactuca L.and the decompo-sition of three macroalgae at different temperature gradients were analyzed.Measurement results dem-onstrated that the decomposition rate of G.livida was the fastest,which was followed by that of S.horneri and U.lactuca L.In the decomposition process,the carbon content of three macroalgae fluctu-ated slightly in the first 24 days of decomposition.The nitrogen content of different macroalgae changed differently,and the phosphorus content declined rapidly at the early stage of decomposition.At the end of the experiment,the phosphorus content decreased.The C/N and C/P of the three mac-roalgae were similar in general.The C/N ratio decreased in the decomposition process.C/P raised first and then falled down.The change of N/P was a little complicated.G.livida showed an up-down fluctua-tion while U.lactuca L.and S.horneri showed a process of rising first and then falling.Correlation analysis showed that the higher the C/N ratio of S.horneri,the lower the decomposition rate,the higher the C/P ratio of U.lactuca L.,the lower the decomposition rate.The decomposition rate of macroalgae remained different at different temperature gradients.The higher the temperature,the faster the decomposition of macroalgae.Our findings indicated that the aged and apoptotic algae should be salvaged in macroalgal culture areas and ma-rine reserves in time,especially in summer when the temperature becomes high.It is necessary to deal with the decaying macroalgae properly to avoid the secondary pollution to the ocean.