4个人工增殖区仿刺参肠道内含物溶解有机质的光谱特性

Spectrum characteristics of dissolved organic matter in the intestinal contents of Apostichopus japonicas from different marine ranching

利用紫外一可见吸收光谱法和三维荧光光谱法研究了4个人工增殖区中仿刺参（Apostichopusjaponicus）前肠内含物溶解有机质（DOM）的光谱特征，从DOM的来源与组成等方面对人工增殖区仿刺参饵料环境状况进行评价。4个人工增殖区仿刺参前肠内含物DOM的紫外光谱数据E3／E4范围为1．56-2．98；DOM的腐殖化程度、芳香性及相对分子量平均值由高到低均依次为莱州、双岛、天鹅湖、俚岛；各海区仿刺参前肠内含物DOM在280nm紫外可见吸光度值差异不显著（P〈0．05），表明仿刺参所摄食沉积质中溶解有机碳（DOC）的相对含量差异不显著，4个资源增殖区提供给仿刺参DOC的能力相近。对仿刺参前肠内含物DOM的三维荧光光谱扫描结果表明，所有DOM的三维荧光光谱图中均出现1个明显的蛋白荧光峰，且峰值强度较高，说明研究区域可能形成蛋白荧光峰的生源物质众多，具有复杂、丰富的饵料生物基础。4个人工增殖区中仿刺参前肠内含物DOM荧光指数（f450／fS00）范围为1．00-1．42，绝大多数接近于1．40，说明其DOM中的腐殖质主要来源于陆源输入，海区易受外源干扰，因此应对海区沉积物来源情况进行持续监测，保证人工增殖区能为海参增殖提供优质沉积物饵料。

Dissolved organic matter （DOM） is abundant in the marine environment, which is one of the largest reser- voirs of carbon on the Earth＇s surface. DOM plays an important role in the biological chemistry cycles, mediating mate- rial flow and energy cycle of the artificial marine ranching ecosystem. In artificial marine ranching, the bottom and other sediments are the direct bait resources of the sea cucumber （Apostichopusjaponicas）. Sediment coming from dif- ferent areas and origins will directly affect ingestion efficiency and digestibility. In the present study, UV-visible spec- troscopy （UV-VIS） and three-dimensional excitation-emission matrix fluorescence spectroscopy （3DEEM） were used to investigate the fluorescence properties of DOM in the intestinal contents of A. japonicus from four different artificial marine ranches. The bait environmental conditions of the A. japonicus were evaluated based on the source and the DOM constituents in the intestinal contents. Spectroscopic characteristics of dissolved organic matter （DOM） were de- termined using ultraviolet absorbance and fluorescence spectroscopy to investigate spatial distribution of DOM compo- sition. The results indicated that the value of E3/E4 ranged from 1.56 to 2.98, the mean value of the humification level, aromaticity and the relative molecular weight is Laizhou〉Shuangdao〉 Swanlake〉Lidao. The results suggested that the baits ofA. japonicus from Laizhou sea area might contain more nitrogen and were more easily enzymatieally digested than the baits from other three sea areas. Meanwhile, the baits of A. japonicas from the Lidao sea area may have a higher physiological and biodegradation activity. No significant difference of absorbency was observed at 280 nm, which suggested that A. japonicus has no preference for the dissolved oxygen content in the sediment. 3DEEM scan- ning indicated an obvious protein fluorescence peak in all images. The diverse sources of protein-like fluorescence in- dicated that these marine ranche shave diverse and complex diet resources. Overall, the value of f450/f500 ranged from 1.00 to 1.42, and was mostly close to 1.40. This may represent the humus in the DOM coming from terrigenous input, which suggested that the food in the marine ranch is influenced by the terrigenous input, and is easily affected by ex- ogenous disturbance. The baits of A. japonicas are complex and influenced by the environment. Any single resource from the environment cannot describe the constituents of the baits. The DOM extracted from the intestinal contents of A. japonicas provide an overview of the baits in the marine ranches. These results indicated that continuous monitoring of the marine sediment is important for ensuring good quality food sources for the precious marine species in artificial marine ranches.