Trophic dynamics of two sympatric mysid species in an estuarine transition zone
Trophic dynamics of two sympatric mysid species in an estuarine transition zone
复制标题
河口过渡区两种同域糠虾的营养动态
DOI：
10.3354/meps332171
复制
发表时间：
2007
影响因子：
2.5
通讯作者：
L. Johnson
中科院分区：
文献类型：
--
作者：
G. Winkler;C. Martineau;J. Dodson;W. Vincent;L. Johnson
对圣劳伦斯河口中部食物网中2种同域性糠虾的摄食生态进行了研究，以确定它们的营养地位和共存机制。这些丰富的掠食者通过觅食行为的差异而明显区分开来。在涉及多猎物组合，捕食和摄食率的糠虾stenolepis的喂养实验大于美洲新糠虾，除了小猎物。M.狭鳞蚌对广背贻贝无节幼体和桡足类的捕食率最高，且对最丰富的食物--多形斑贻贝面盘幼体不取食。与此相反，N.美洲轮虫对轮虫、无节幼体和面盘幼体等小型猎物的捕食率最高，并表现出偏好。当首选的猎物密度下降，在下半年的实验中，这两种糠虾表现出转向捕食的首选猎物。M. stenolepis转为滤食性，对面盘幼虫的捕食率较高，而N. americana对小E.近亲桡足类稳定同位素分析和摄食实验表明，在食物网中存在3个营养级，具有高度的杂食性。2种糠虾的δ 13 C值相似，碳源相同，且多为原地来源。而δ 15 N值相差2.2‰，表明它们的食物组成在摄食和同化方面存在差异。这些结果表明，共存的同域性糠虾种群是通过减少竞争，由于食物生态位划分。灵活的觅食行为允许糠虾利用多个猎物群体，在高度动态的河口过渡区的圣劳伦斯河中河口的时间和空间的波动。
The feeding ecology of 2 sympatric mysid species within the food web of the St. Lawrence Middle Estuary was studied to determine their trophic position and potential mechanisms of coexistence. These abundant predators were clearly distinguished by differences in foraging behaviour. In feeding experiments involving multi-prey assemblages, predation and ingestion rates of Mysis stenolepis were greater than for Neomysis americana, except for small prey. M. stenolepis showed highest predation rates on and preference for Eurytemora affinis nauplii and copepodites, and did not feed on the most abundant prey, the veliger stage of the zebra mussel Dreissena poly- morpha. In contrast, N. americana showed highest predation rates on and preference for small prey species such as rotifers, nauplii and veligers. When densities of preferred prey declined in the second half of the experiment, both mysid species showed a shift in predation towards the less preferred prey. M. stenolepis switched to filter feeding, with higher predation rates on veligers, whereas N. americana increased predation on small E. affinis copepodites. Stable isotope analysis and feeding experiments suggested 3 trophic levels in the food web, with a high degree of omnivory. The δ 13 C values for the 2 mysid species were similar and supported by the same carbon source, mostly of autochthonous origin. However, their δ 15 N differed significantly by 2.2‰, indicating that the compo- sition of their diet differed in terms of ingested and assimilated food items. These results suggest that co-existence of the sympatric mysid populations is achieved by reduced competition due to food- niche partitioning. Flexibility in their foraging behaviour allowed mysids to exploit multiple prey groups that undergo temporal and spatial fluctuations in the highly dynamic estuarine transition zone of the St. Lawrence Middle Estuary.