Analytical studies on benthic food webs of aquatic ecosystems using stable isotope analyses

利用碳、氮和硫稳定同位素对河口、河流和湖泊生态系统中的底栖生物食物网进行了调查。作为一个简单的湖泊生态系统，我们考察了Katanuma酸性火山湖，它的群落结构非常简单。以沉积摄食的环虫幼虫（Chironomus acerbiphilus）为食源及其潜在的食材（底栖硅藻和浮游植物）进行了摄食实验。结果表明，嗜酸梭菌幼虫选择性地吸收浮游植物和底栖硅藻作为大块沉积物的新鲜沉积物，并且吸收浮游植物比吸收底栖硅藻更容易。沉积物中底栖硅藻的同化速率随水深的增加而降低，而浮游植物的同化速率随水深的增加而增加。在半封闭的河口泻湖（加莫泻湖）、南秋田河河口两个地点调查了底栖动物的食物来源和消费者的饮食，并从潜在食物来源（河流和陆生植物材料、参与物质、大型藻类、底栖和附生硅藻）的同位素值中阐明了更多的问题。2源混合模型显示，底栖硅藻是悬浮型和表层沉积物型取食动物的重要饲粮，提示重悬浮硅藻在饲料中的重要性。相比之下，浮游植物在浮游植物生物量相当高的内泻湖成为重要的食物。通过对两级山溪中毛翅目昆虫食物来源的分析，发现两级山溪中大部分毛翅目昆虫的主要食物均为陆生植物的底栖颗粒有机物，且食物来源在两级山溪间无明显差异。此外，我们还估算了源流中大型无脊椎动物的食物来源。蜗牛Semisulcospira libertina从其他相关的大型无脊椎动物吸收不同的食物来源。趋化自养细菌的生产为溪流中蜗牛的食物来源做出了贡献，即使在大多数有氧栖息地也是如此。少

Investigations of benthic food webs were conducted in estuarine, riverine and lake ecosystems using carbon, nitrogen and sulfur stable isotopes.1. As a simple lake ecosystem, we examined the acidic volcanic Lake Katanuma, which has a very simple community structure. We conducted feeding experiments using a deposit-feeding chironimid larvae (Chironomus acerbiphilus) as the consumer and its potential diets (benthic diatom and phytoplankton). The results showed C. acerbiphilus larvae selectively assimilated phytoplankton and benthic diatoms as fresh deposits from bulk sediments, and assimilated phytoplankton more readily than benthic diatoms. The assimilation rate of benthic diatoms from sediments by the larvae tended to decrease with increasing water depth, while the rate of phytoplankton tended to increase with depth.2. Food sources of benthic consumer were investigated at two locations in a semi-enclosed estuarine lagoon (gamo Lagoon), the Nanakita-river estuary, and diet of the consum … More ers were elucidated from the isotopic values of potential food sources (riverine and terrestrial plant materials, participate matter, macroalgae, benthic and epiphytic diatoms). A 2-source mixing model revealed that benthic diatoms were the important diet of suspension feeders as well as surface-deposit feeders, suggesting the dietary importance of resuspended diatoms. In contrast, phytoplankton became an important diet in the inner lagoon where phytoplanktonic biomass was considerably high.3. We analyzed food sources of Trichoptera in two first-order mountain streams, which indicated that the main food of most Trichoptera species in both streams was benthic particulate organic matter derived from terrestrial plants, and that the food sources did not differ markedly between the streams. In addition, we estimated the food sources of macroinvertebrates in a headwater stream. The snail Semisulcospira libertina assimilated different food sources from other associated macroinvertebrates. The production by chemoautotrophic bacteria contributes to the food sources of a snail in a stream, even in mostly aerobic habitats. Less