Mean redox potential values in surface sediments along the transect D in the Cretan Sea (Table 1)

The seasonal, spatial and bathymetric changes in the distribution of chloroplastic pigments (Chl a, phaeopigments and CPE), TOC, TON, ATP, bottom water nutrient content and the main biochemical classes of organic compounds (lipids, proteins and carbohydrates) were recorded from May 1994 to September 1995 over the continental margin of northern Crete. The concentration of chloroplastic pigment equivalents (CPE) was always low, dropping dramatically along the shelf-slope gradient. Microbial activity (ATP) also dropped sharply beyond the continental shelf following a distribution pattern similar to TOC and TON. Lipid, protein and carbohydrate concentrations, as well as biopolymeric carbon were comparable to those reported for other more productive areas, however, the quality of the organic matter itself was rather poor. Thus, carbohydrates, the dominant biochemical class, were characterised by being highly (80–99%) refractory, as soluble carbohydrates represented (on annual average) only 6% of the total carbohydrate pool. Protein and lipid concentrations strongly decreased with depth, indicating depletion of trophic resources in the bathyal zone. Proteins appeared to be the more degradable compounds and indeed the protein to carbohydrate ratios were found to decrease strongly in the deeper stations. Organic matter content and quality decreased both with increasing distance from the coast and within the sediment. All sedimentary organic compounds were found to vary between sampling periods, with the changes being more pronounced over the continental shelf. The different temporal patterns of the various components suggest a different composition and/or origin of the OM inputs during the different sampling periods. The amount of material reaching the sediments below 540 m is extremely low, suggesting that most of the organic material is decomposed and/or utilised before reaching the sea floor. In conclusion, the continental shelf and bathyal sediments of the Cretan Sea can be considered, from a trophic point of view, as two different subsystems.

1994年5月至1995年9月，研究人员在克里特岛北部大陆边缘海域，记录了叶绿素类色素（chloroplastic pigments，包含叶绿素a（Chl a）、褐藻素（phaeopigments）与色素等效物（CPE，chloroplastic pigment equivalents））、总有机碳（TOC）、总有机氮（TON）、三磷酸腺苷（ATP）、底层海水营养盐含量，以及有机化合物主要生化组分（脂质、蛋白质与碳水化合物）的分布随季节、空间及水深的变化特征。色素等效物（CPE）的浓度始终处于较低水平，且沿陆架-陆坡梯度急剧下降。微生物活性（ATP）同样在越过大陆架后大幅降低，其分布模式与总有机碳（TOC）、总有机氮（TON）高度相似。脂质、蛋白质与碳水化合物的浓度，以及生物聚合碳含量，与其他生产力更高海域的报道值相当，但有机质本身的质量较差。其中作为主导生化组分的碳水化合物表现出极强的难降解性，难降解比例达80%~99%，年均可溶性碳水化合物仅占总碳水化合物库的6%。蛋白质与脂质浓度随水深显著降低，表明半深海带的营养资源已被显著消耗。蛋白质被认为是更易降解的化合物，且确实在站位水深增加时，蛋白质与碳水化合物的比值显著下降。有机质的含量与质量均随离岸距离的增加以及沉积物内部深度的增加而降低。所有沉积有机组分均随采样周期发生变化，其中陆架区域的变化更为显著。不同组分的时间变化模式存在差异，暗示不同采样周期内的有机质输入物在组成和/或来源上有所不同。水深超过540米的海域沉积物中，到达的有机质含量极低，这表明大部分有机质在抵达海底前就已被分解和/或利用。综上，从营养生态学角度来看，克里特海的大陆架与半深海沉积物可被视为两个独立的子系统。