Contributions of habitat sampling and alkalinity to diatom diversity and distributional patterns in streams: implications for conservation

Abstract

Diatoms, microscopic unicellular algae, have been widely sampled from streams around the world because of their use in biological assessments, but as a result they are often only collected from epilithic habitats in riffles, which may lead to a substantial underreporting of their diversity and distributional patterns. The goals of this study were to identify how sampling methods and water chemistry affect the characterization of local and regional diversity and distributions. Species richness, Shannon diversity, and evenness were significantly greater in multiple habitat (MH) than epilithic habitat (EH) samples (paired t-test; P \ 0.01). At the local scale, MH sampling yielded 76% of the total species collected (42% unique), EH sampling captured 58% (24% unique), and 34% were shared. From MH samples, 3, 28, and 60 regionally rare species were collected from[75,[50, and [25% of sites, respectively, whereas 1, 14, and 34 were collected from EH samples, respectively. Regional abundance more strongly predicted site frequency than mean local abundance. Smaller drainage basins tended to have fewer species, likely because of species-area relationships, but local factors (% EH and alkalinity) influenced the taxonomic complexity of assemblages. Diversity was greatest at intermediate % EH, but low alkalinity reduced diversity, which is potentially important for ecosystems affected by anthropogenic acidification, as in our study. Multiple habitats need to be sampled for better documenting diatom diversity and distributions, which could improve conservation efforts at local and regional scales along with the characterization of ecological patterns and processes.

Suggestions for diatom-based monitoring in intermittent streams

“…Indeed, beside better classifying intermittent streams, multi-habitat sampling presents also important implications in documenting species distribution and autecology. In heterogeneous streams, MHs potentially host rare and under-dispersed diatom species, which present higher risks for regional extinction and are largely underestimated through the sole traditional sampling approach (Smucker and Vis, 2011). Indeed, for biodiversity assessment purposes, samplings from different MHs are more advisable (Jüttner et al, 1996).…”

“…Multi-habitat sampling would provide a better representation of the site conditions and integrate the information missed in a single standard sampling (Smucker and Vis, 2011). The analysis of different MHs can also provide important information in terms of species autecology.…”

Diatom flora in Mediterranean streams: flow intermittency threatens endangered species

“…This species was significantly present in pristine sites characterized by microlithal as the main substrate, and its abundance was not limited by isolation from the main flow. Nitzschia tabellaria, considered as being characteristic of habitats of high conservation value (Potapova and Charles 2007;Smucker and Vis 2011) was particularly abundant in the UP site of the Argentina stream.…”

High diatom species turnover in a Baltic Sea rock pool metacommunity

“…Variation among these communities thus potentially affects the whole ecosystem, and better knowledge of the key factors determining microbial communities is urgently needed (Van der Gucht et al 2007). Due to their high diversity, relatively well-defined habitat preferences, short generation times, and generally-yet not invariably-geographically wide distribution, microbial algae such as diatoms are useful model taxa in testing different ecological theories over short timescales (Smucker and Vis 2011). So far, studies of community dynamics and especially spatiotemporal variation in species composition for microbial eukaryotic organisms are still rare compared with those of macroorganisms (Martiny et al 2006;Meier and Soininen 2014).…”