Declines in littoral species richness across both spatial and temporal nutrient gradients: a palaeolimnological study of two taxonomic groups

Abstract

Summary 1. Using a palaeolimnological approach in shallow lakes, we quantified the species richness responses of diatoms and Cladocera to phosphorus enrichment. We also examined differences in species richness responses between littoral and pelagic assemblages of our focal communities. To address both spatial and temporal relationships, our study includes an analysis of both surface sediments from 40 lakes and of a lake sediment record spanning c. 120 years. The objective of our study was to determine whether similar species richness patterns occurred across trophic levels, as well as along spatial and temporal gradients. 2. We found that both diatom and Cladocera species richness estimates significantly declined with increasing phosphorus across space and through time. When the assemblages were subdivided according to known habitat preferences, littoral biodiversity maintained a negative trend, whereas pelagic species richness tended to show no relationship with phosphorus. 3. Negative productivity–diversity patterns have been observed across almost all palaeolimnological studies that span large productivity gradients. This congruence in patterns is most likely due to the similarity in data collection methods and in focal communities studied. The contrasting responses between littoral and pelagic assemblages may be explained by the differences in physical habitat and the pool of taxa in each of these environments. Consistent with the literature, we found statistical support for the idea that littoral diversity declines could be explained by an interaction between macrophytes and nutrients along strong trophic gradients. The general lack of a diversity response in our pelagic assemblages could be attributable to the limited pool of subfossil taxa. The response of the pelagic diatom could also be related to their broad range of nutrient tolerances. 4. The observed negative response of species richness to phosphorus enrichment, particularly in the littoral assemblages, has implications for ecosystems functioning because communities with reduced biodiversity often are less resilient to anthropogenic change.

Diatom diversity patterns over the pastc. 150 years across the conterminous United States of America: Identifying mechanisms behind beta diversity

“…We identified a very low threshold for the proportion of development in the watershed that impacted LCBD (Figure ). The effect on LCBD at a very low level of development might be attributable to the tendency for humans to modify shorelines even when the rest of the watershed may be intact (e.g., by removing riparian and littoral vegetation; Kaufmann et al, ), which in turn has substantial consequences for diatoms (Velghe, Vermaire, & Gregory‐Eaves, ) and other organisms (Strayer & Findlay, ). The relationship with forest cover indicates that less forest cover may produce downstream environmental conditions that favour specific species or genera; hence, these lakes may contribute more to total beta diversity because they are exceptional in nature.…”

Extrinsic vs. Intrinsic Regimes Shifts in Shallow Lakes: Long-Term Response of Cyanobacterial Blooms to Historical Catchment Phosphorus Loading and Climate Warming

“…The community composition of cladocera in the study region is driven largely by nutrient concentration and macrophyte abundance (Velghe et al, 2012). For PSF Lake, the chydorid data were previously published in study of a shorter sediment core (Richard Albert et al, 2010).…”

Relationship between cladoceran (Crustacea) functional diversity and lake trophic gradients

“…Some studies have investigated biodiversity patterns from sedimentary archives along different spatial and temporal gradients utilizing information extracted from both surface sediments and sediment cores (Richard Albert et al . ; Velghe, Vermaire & Gregory‐Eaves ). Recent literature has emphasized the importance of integrating palaeolimnological approaches with biodiversity science, highlighting the possibilities of a long‐term perspective on issues in biodiversity and conservation (Froyd & Willis ; Gregory‐Eaves & Beisner ).…”

“…Furthermore, biodiversity indices for determining species richness and diversity have been used to track long-term biodiversity dynamics of aquatic communities under environmental changes (Korosi & Smol 2012;Thienpont et al 2013;Ilyashuk et al 2015). Some studies have investigated biodiversity patterns from sedimentary archives along different spatial and temporal gradients utilizing information extracted from both surface sediments and sediment cores (Richard Albert et al 2010;Velghe, Vermaire & Gregory-Eaves 2012). Recent literature has emphasized the importance of integrating palaeolimnological approaches with biodiversity science, highlighting the possibilities of a long-term perspective on issues in biodiversity and conservation (Froyd & Willis 2008;Gregory-Eaves & Beisner 2011).…”