Chen, G.Dalton, C.Leira Campos, Antón ManoelTaylor, DavidIrvine, Kenneth2024-02-122024-02-122009Leira, M., Chen, G., Dalton, C., Irvine, K. and Taylor, D., 2009. Patterns in freshwater diatom taxonomic distinctness along an eutrophication gradient. Freshwater Biology, 54(1), pp.1-14.0046-5070http://hdl.handle.net/10347/32815This is the peer reviewed version of the following article: Leira, M., Chen, G., Dalton, C., Irvine, K. and Taylor, D., 2009. Patterns in freshwater diatom taxonomic distinctness along an eutrophication gradient. Freshwater Biology, 54(1), pp.1-14., which has been published in final form at https://doi.org/10.1111/j.1365-2427.2008.02086.x1. A variety of species richness measures have been used to assess the effects of environmental degradation on biodiversity. Such measures can be highly influenced by sample size, sampling effort, habitat type or complexity, however, and typically do not show monotonic responses to human impact. In addition to being independent of the degree of sampling effort involved in data acquisition, effective measures of biodiversity should reflect the degree of taxonomical relatedness among species within ecological assemblages and provide a basis for understanding observed diversity for a particular habitat type. Taxonomic diversity or distinctness indices emphasize the average taxonomic relatedness (i.e. degree of taxonomical closeness) between species in a community. 2. Eutrophication of freshwater ecosystems, mainly due to the increased availability of nutrients, notably phosphorus, has become a major environmental problem. Two measures of taxonomic distinctness (Average Taxonomic Distinctness and Variation in Taxonomic Distinctness) were applied to surface sediment diatoms from 45 lakes across the island of Ireland to examine whether taxonomic distinctness and nutrient enrichment were significantly related at a regional scale. The lakes span a range of concentrations of epilimnic total phosphorus (TP) and were grouped into six different types, based on depth and alkalinity levels, and three different categories according to trophic state (ultra-oligotrophic and oligotrophic; mesotrophic; and eutrophic and hyper-eutrophic). 3. The taxonomic distinctness measures revealed significant differences among lakes in the three different classes of trophic state, with nutrient-rich lakes generally more taxonomically diverse than nutrient-poor lakes. This implies that enrichment of oligotrophic lakes does not necessarily lead to a reduction in taxonomic diversity, at least as expressed by the indices used here. Furthermore, taxonomic distinctness was highly variable across the six different lake types regardless of nutrient level. 4. Results indicate that habitat availability and physical structure within the study lakes also exert a strong influence on the pattern of taxonomic diversity. Overall the results highlight problems with the use of taxonomic diversity measures for detecting impacts of freshwater eutrophication based on diatom assemblages.engThis article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.http://creativecommons.org/licenses/by-nc-nd/4.0/DiatomsDiversityIrelandNutrient enrichmentTaxonomic distinctness241704 Limnología241707 Algología (ficología)journal article10.1111/J.1365-2427.2008.02086.X1365-2427open access