| 摘要: |
| 13C/12C比值在海洋生态系统营养关系研究中的应用──海洋植物的同位素组成及其影响因素的初步探讨
于1993年2月–1995年5月，采用生物显微镜鉴定并计数和高温氧化的方法，对崂山湾海洋植物的种类组成及其有机碳同位素组成的季节性变化作了5个季度月的研究。结果表明，该区同采浮游植物全年以硅藻为主，甲藻在夏季也可成为优势种之一。浮游植物的碳同位素组成在夏季较重，冬季和春季较轻，并与海水温度有弱的正相关性。浮游植物δ13C值的变化范围为-25.9×10-3 – -19.2×10-3，全年平均值为 (-23.2±2.4)×10-3。该生态系统的另一碳源为底栖藻类，其δ13C平均值为(-18.5±2.4)×10-3，明显区别于浮游植物。对除温度以外的其它影响海洋植物同位素组成的因素，诸如植物种类组成、海水中溶解无机碳δ13C值、CO2供应速率以及CO2固定过程中不同验化酶的同位素分馏作用等也作了初步探讨。 |
| 关键词: 碳同位素 食物网 植物 |
| DOI： |
| 分类号: |
| 基金项目:国家自然科学基金资助项目，39170172号 |
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| APPLICATION OF 13C/12C RATIOS TO STUDIES OF TROPHIC RELATION IN A MARINE ECOSYSTEM—PRELIMINARY INQUIRY INTO ISOTOPIC COMPOSITIONS OF MARINE PLANT AND THEIR INFLUENCE FACTORS |
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CAI De-ling, MAO Xing-hua, HAN Yi-bing
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First Institute of Oceanography, State Oceanic Administration, Qingdao, 266003
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| Abstract: |
| Understanding of isotopic compositions of marine plant and their influence factors is a foundation for studies on trophic structure in a marine ecosystem. Seasonal variations in the species constituents of marine plants and their organic carbon isotopic compositions in Laoshan Bay were measured quarterly five times. The results show that the species constituents of phytoplankton take diatoms and dinoflagelates as the dominant. The diatoms have 32 genera and 57 species, but the dinoflagelates have only 3 genera and 7 species. The former is absolutely superior both in species and in quantity. The predominant species can have some seasonal changes. Nitzschia sp., Melosira sulcata and Coscinodiscus spp. rank the first three places in numbers in winter; Coscinodiscus spp. rises up to the first, Rhizosolenia sp. and Nitzschia sp. the second and third, respectively, in spring; the superiority of Coscinodiscus spp. is more obvious, but the amount of dinoflagelates increases clearly, of which Ceratium spp. becomes the second predominant, with Chaetoceros spp. being the third in summer. Coscinodiscus spp. possesses absolute predominance in autumn. This result is consistent with that investigated in 1987–1988. In different years the predominant species in a season, however, may have some changes. The isotopic compositions of phytoplankton are heavier in summer, but lighter in winter and spring. They have a weaker positive relation with seawater temperature (the relative coefficient is 0.69). The δ13C value of phytoplankton range between -25.9×10-3 and -19.2×10-3, with an annual mean of (-23.2±2.4)×10-3. Another carbon source in the ecosystem is benthic algae. They have 9 species. The δ13C values of green algae range from -22.9 – -18.9×10-3, brown algae -19.1 – -15.2×10-3, and red algae -21.7–17.6×10-3. The average of their δ13C values is (-18.5±2.4)×10-3, having an evident difference from that of phytoplankton. These data provide a basis for studies on trophic levels in the food web by isotopic methods. In addition to seawater temperature, other factors affecting isotopic compositions of marine plants include species component, δ13C values of dissolved inorganic carbon in seawater, rate of CO2 supply and isotopic fractionation of the different carboxylation enzyme in the process of CO2 fixation. |
| Key words: Carbon isotopes, Food web, Plants |
