Structuring of epilithic biofilms by the caddisfly Tinodes rostocki: photosynthetic activity and photopigment distribution in and beside larval retreats

Aquatic Microbial Ecology

Peter Stief¹  Georg Becker¹ 

关键词: Stream;    Epilithic biofilm;    Microalgae;    Photosynthesis;    Trichoptera;    Grazing;    Microsensors;    Photopigments;   

DOI  :  10.3354/ame038071

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: Tinodes rostocki larvae (Trichoptera: Psychomyiidae) cover large proportions of stream hard substrata with retreats constructed of mineral particles and larval silk. We consider these retreats as 3-dimensional extensions of the epilithicbiofilm that may possess a distinct microenvironment, community metabolism and composition. Therefore, we compared the photosynthetic/respiratory activities (O₂ and pH microsensors) and the photopigment composition (HPLC) of larval retreats andthe surrounding epilithic biofilms. In retreats, pigment contents and photosynthetic/respiratory activities were highest in sections with a visible microphytobenthic biofilm that were mostly the older parts of the retreats. In contrast, newly constructedsections of the retreats and the surrounding epilithic biofilm had approximately 5-fold lower values. The fucoxanthin-to-chlorophyll ratio of the retreat biofilm was high (fuco/chl a = 1.27) and indicated diatom dominance, which was not evident inthe surrounding epilithic biofilm (fuco/chl a = 0.15). Experimental transplantation of larval retreats to microscope slides allowed microsensor measurements through the 500 to 700 µm-thick wall and inside the lumen. In the light,O₂ concentration and pH values increased significantly across the wall and remained high in the lumen of the retreat, whereas in darkness O₂ and pH depressions in both wall and lumen were moderate or even absent. Our data suggestthat T. rostocki larvae construct and maintain retreats with a particular physico-chemical microenvironment that favours a distinct microbial community. Thereby, abundant T. rostocki larvae might significantly influence benthic primaryproduction and heterotrophic metabolism in small streams.

【 授权许可】

Unknown