Ecological uniqueness of stream and lake diatom communities shows different macroecological patterns

Abstract

AimTo discover whether lake and stream diatom communities show different patterns in species richness and in their local (LCBD) and species (SCBD) contributions to beta diversity in relation to macroscale environmental characteristics.LocationFinland.MethodsAs biological data, we used diatom samples collected from Finnish stream (n = 492) and lake (n = 290) sites. As explanatory variable data, we used information on macroscale environmental and historical aspects, such as bedrock, soil and post‐glacial highest shoreline. We also accounted for catchment areas, different levels of isolation and relative centrality of the study sites. We ran multiple linear models and selected best models based on AICc values.ResultsWe found that macroscale factors affecting diatom richness and ecological uniqueness differed clearly between streams and lakes. LCBD and species richness of stream communities were more affected by regional environmental characteristics, whereas LCBD and species richness of lake communities were more often driven by spatial measures. The measures of LCBD and species richness showed a slightly negative relationship in streams, but no such relationship was detected in lakes. Also, we showed that, for both streams and lakes, SCBD was strongly determined by the number of sites occupied by a species and the overall abundance of a species.Main conclusionsOur findings related to the distinction between the determinants of lake and stream species richness or LCBD may be tied to the different hydrological connectivity levels occurring in freshwater lotic and lentic systems. Also, in streams, sites with exceptional ecological uniqueness seem to have a rather low number of species. Our findings may be applied to biological conservation and monitoring planning, emphasizing that not only species‐rich but also unique low‐richness sites may be valuable conservation goals.

Knitting patterns of biodiversity, range size and body size in aquatic beetle faunas: significant relationships but slightly divergent drivers

“…water area and wetlands) did not contribute strongly to species richness, we can refute the hypothesis that habitat area per se accounts for variation in species richness at this spatial scale. Although the negative relationship between species richness and LCBD has been noted before in empirical studies of local ecological assemblages (Legendre & De Cáceres, 2013;Heino & Grönroos, 2017;Vilmi et al, 2017;Landeiro et al, 2018), to our knowledge, no study has examined the relationship of LCBD with temperature at large spatial scales across biogeographical provinces. Instead, although we cannot completely rule out the effects of ice age history on the species richness pattern of diving beetles in an area where ice sheet of the Last Glaciation Maximum retreated in a stepwise way between 25 000 and 8000 years before present (Denton & Hughes, 1981;Kleman & Hättestrand, 1999;Houmark-Nielsen et al, 2012), we can nevertheless suggest that climate affects the most variation in species richness across the study area.…”

“…Recently, Legendre and De Cáceres (2013) devised a method to decompose total beta diversity in the contributions of species or sites, where the relative ecological uniqueness of sites can be evaluated [i.e. Empirical research on the topic has thus far revealed that species richness is typically negatively correlated with LCBD across local ecological assemblages, although there is some variation around the relationship (Legendre & De Cáceres, 2013;, Vilmi et al, 2017, Landeiro et al, 2018, da Silva et al, 2018. Empirical research on the topic has thus far revealed that species richness is typically negatively correlated with LCBD across local ecological assemblages, although there is some variation around the relationship (Legendre & De Cáceres, 2013;, Vilmi et al, 2017, Landeiro et al, 2018, da Silva et al, 2018.…”

Geo‐climatic factors drive diatom community distribution in tropical South American freshwaters

“…Our results seem to be consistent with the idea that the strong physical structuring of the study regions, with the distinct climatic and topographic conditions, override local environmental effects (partially supporting H1). Previous studies have also demonstrated the importance of macroscale descriptors over water chemistry in shaping aquatic community composition (diatoms and macroinvertebrates) in Arctic (Mykrä, Heino, & Muotka, ; Pajunen, Luoto, & Soininen, ; Vilmi, Karjalainen, & Heino, ), temperate (de Mendoza & Catalan, ) and tropical freshwaters (Matthews‐Bird et al., ; Steinitz‐Kannan et al., ).…”

Using traits to explain interspecific variation in diatom occupancy and abundance across lakes and streams

“…Shurin, Cottenie, & Hillebrand, ). Earlier studies have shown that lakes and streams partly foster different diatom communities (Kahlert & Gottschalk, ; Soininen & Weckström, ), and that they show differences in species richness and ecological uniqueness patterns (Vilmi, Karjalainen, et al., ). Keeping these earlier observations in mind, it is possible that the differences we now found regarding occupancy and abundance in lakes and streams may be related to levels of connectedness.…”

“…To rule out excessive seasonal effects, only samples taken in autumn were considered. A detailed description of the diatom database and data harmonization is presented in Vilmi, Karjalainen, and Heino ().…”