Climate impacts
Diatoms often break the smaller-when-warmer rule
Open access · cc by · source: Europe PMC
Across a 20°C Icelandic stream gradient, diatom size did not shrink with warmth; composition, not plastic shrinkage, drove size differences.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
Not yet placed on a claim. This paper has study layers, but no concept page yet cites it as support, challenge, or qualifier.
Inspect source passages
Diatoms often break the smaller-when-warmer rule
These passages occur verbatim in the stored paper text. They support the points listed below; they do not verify every statement in the explanation.
31 diatom species present in two or more streams were used for the intraspecific analysis
There were 31 diatom species present in two or more streams, and these were used in the intraspecific analysis.
Of 91 pairwise comparisons, 51 size differences were solely due to compositional shifts
Of 91 pairwise comparisons between average community body size in the fourteen streams (), 51 showed that the observed difference in average community body size was solely due to compositional shifts
Key findings
Among 31 species, 16 had negative size–temperature slopes and 15 positive; the combined test for shrinking was nonsignificant (P=0.186). Community mean size had no clear temperature relationship. Of 91 pairwise comparisons, 51 were due solely to compositional shifts; mixed cases averaged only 21.8% from intraspecific change. Species turnover averaged 14.8% of compositional differences—relative abundance dominated.
Methodology
Authors sampled diatom assemblages in 14 geothermally heated Icelandic streams spanning about 20°C within 2 km. They measured body size for 31 species present in two or more streams, tested James’ and Bergmann’s rules, and partitioned community size differences into intraspecific change, relative-abundance shifts, and species turnover.
Limitations
Geothermal warming is a spatial proxy, not a multi-decadal climate time series. Other variables (pH, silicate) also related to size. Results are for benthic stream diatoms, not ocean phytoplankton. Mechanisms (metabolism vs competition vs grazing) were not experimentally isolated.
Related papers in this topic
Same topic cluster — not a recommendation engine.