Benthic cyanobacterial mats serve as a refuge and food for the amphipod Gammarus fasciatus

• Published in: Hydrobiologia 2015-10, Vol.758 (1), p.171-181
• Main Authors: Lévesque, David, Cattaneo, Antonella, Hudon, Christiane
• Format: Article
• Language: English
• Subjects: Analysis; Aquatic ecosystems; Aquatic plants; benthic organisms; Biomedical and Life Sciences; carbon; Chemical composition; Diet; Ecology; elemental composition; epiphytes; Food; Freshwater & Marine Ecology; Gammarus fasciatus; Habitats; invertebrates; isotopes; laboratory experimentation; Life Sciences; Lyngbya; Lyngbya wollei; macrophytes; Marine toxins; mixing; nitrogen; omnivores; Primary Research Paper; Rhizoclonium; saxitoxins; Spirogyra; statistical models; wool; Zoology
• ISSN: 0018-8158; 1573-5117
• DOI: 10.1007/s10750-015-2288-z

We investigated the ecological role of Lyngbya wollei (Farlow ex Gomont, comb. nov.) cyanobacterial mats in aquatic ecosystems, especially as a food source and shelter for the amphipod Gammarus fasciatus (Say). For this, we offered amphipods a choice between mats of L. wollei and either chlorophytes (Spirogyra, Rhizoclonium) or an artificial mat made of acrylic wool in laboratory experiment. Moreover, we reconstructed in situ amphipod diet using a dual isotope mixing model (δ¹³C and δ¹⁵N). G. fasciatus consistently selected the substratum offering the best light refuge (Acrylic > Lyngbya = Rhizoclonium > Spirogyra). Neither the presence/absence of saxitoxins, nor the tissue elemental composition and epiphyte abundance exerted any significant effect on substratum choice. L. wollei and its epiphytes constituted 36 and 24%, respectively, of the in situ diet of G. fasciatus, whereas chlorophytes, macrophytes, and associated epiphytes represented a less important fraction of its diet. Benthic cyanobacterial mats should be considered a good shelter and food source for small omnivorous invertebrates such as amphipods.