查看更多>>摘要：Epiphytic biofilm is an important component in freshwater ecosystems and is one of the main primary producers in shallow freshwater ecosystems. The epiphytic biofilm is comprised of an autotrophic community made up of diatoms, green algae, and cyanobacteria, and a heterotrophic community consisting of bacteria, protozoa, fungi, and other microorganisms. Macrophytes are the host domain for epiphytic biofilm, providing substrate and influencing epiphytic biofilm via structural characteristics. Strong competitive, mutualistic, and commensalistic relationships between epiphytic biofilm and macrophytes have resulted from interactions for resources (e.g., light and nutrients) and trophic and allelopathic dynamics. Even though these interactions have widerimplications on ecosystem structure, function, and integrity, the current understanding of epiphytic biofilm-macrophyte interactions is limited. In this review, we highlight the current understanding of epiphytic biofilms in freshwater ecosystems and synthesize their different interactions with macrophytes by providing illustrative examples. Furthermore, we identify key areas where research is currently lacking and provide directions for future research in this field, which will allow for better integrated aquatic ecosystem management and conservation strategies.
查看更多>>摘要：Seagrass meadows with more than two species co-occurring at a small scale are unusual in temperate regions, and such multispecies seagrass beds are undocumented in the Northeastern Pacific. Seagrasses in multispecies beds may coexist through trait differentiation in body size, life history types and phenology, especially when competitive exclusion is interrupted by environmental variability. Here, we survey and manipulate a multispecies seagrass meadow in Willapa Bay, Washington (USA), containing Zostera marina, Zostera japonica and Ruppia maritima; our 13-month survey is the first formal documentation of multispecies seagrass bed occurrence in the Northeastern Pacific. Z. japonica, a non-native species, reached an end-of-summer biomass that was anorder of magnitude greater than either native seagrass. To test competition, we experimentally removed Z. japonica and found competition occurred disproportionately on the smaller R maritima relative to larger Z. marina. R. maritima germinated later andsenesced earlier than the two Zostera species, and the removal of Z. japonica positively affected R. maritima biomass, supporting previous studies that R. maritima is an opportunistic species. In addition to species-specific phenology and body size, allspecies presented annual life histories and thus began each annual cycle under high resource availability, such as light, space and nutrients, which may contribute to coexistence.
查看更多>>摘要：High morphological variation of Typha L. species (Typhaceae) inspires some authors to describe new taxa. We aim to test genetic distinctiveness of some taxa reported in East Europe on morphological basis to verify their taxonomical status. We use sequences of intergenic spacer rpl32-trnL of cpDNA that was shown to be a reliable molecular marker in non-hybrid Typha species. We found that T. caspica Pobed., T. elata Boreau, T. incana Kapit. et Dyukina, T. krasnovae Doweld, T. rossica Krasnova are genetically identical to T. latifolia L., as well as T. foveolata Pobed., T. austro-orientalis Mavrodiev, T. elatior Boenn., T. angustata Bory et Chaub., T. linnaei Mavrodiev et Kapit. to T. angustifolia L. Thus, until some additional evidence of their distinctiveness is not found, we suggest to treat T. caspica, T. elata, T. krasnovae, T. rossica as synonyms of T. latifolia, while T. foveolata, T. austro-orientalis, T. elatior, T. angustata should be synonymized with T. angustifolia. Consequently, T. linnaei is a superfluous name (coined in attempts of neotypification T. angustifolia) and should be also considered synonymous to the latter. The hypothesis of hybrid origin of T. incana should be tested further with microsatellite DNA repeats - if correct, this would indicate T. latifolia as plastid donor.
Iversen, Lars LonsmannGiron, Jorge GarciaPan, Yingji
4页
查看更多>>摘要：Functional biogeography has advanced the field of functional ecology into a more spatially-predictive science. However, freshwater plants are still underrepresented in these trait-based advancements. Here, we argue that there is a need for developing a functional biogeographical framework for freshwater plants and initiate global mapping efforts focusing on the form and function of freshwater plants. Specific attention should be given to (1) the placement of freshwater plants in the global plant trait space and show how this placement links to global trait-environment relationships; (2) the theoretical framework for major structural trait-trait correlations based on the physical constraints in aquatic ecosystems; (3) the evolutionary and environmental drivers underlying the global distribution of inter- and intra-specific variation in different life forms; and (4) the level of equilibrium between spatial and temporal trait-environment relationships in freshwater plants. By putting freshwater plants in the context of these spatial aspects, we could advance our understanding of freshwater plant adaptations and responses to environmental gradients, and thereby facilitate predicting the consequences of global changes for freshwater ecosystem functions and services.
NSTL
Elsevier