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Community- and population-level changes in diatom size structure in a subarctic lake over the last two centuries.

Kerrigan EA, Irwin AJ, Finkel ZV - PeerJ (2015)

Bottom Line: Climate change over the last two centuries has been associated with significant shifts in diatom community structure in lakes from the high arctic to temperate latitudes.To test the hypotheses that recent climate warming selects for species of smaller size within communities and a decrease in the average size of species within populations, we quantified the size of individual diatom valves from 10 depths in a sediment core covering the last ∼200 years from a pristine subarctic lake.In the surface sediments that correspond to the recent decades when air temperatures have warmed, the mean size of valves in the diatom community has significantly decreased due to an increase in the proportion of smaller-sized planktonic diatom species.

View Article: PubMed Central - HTML - PubMed

Affiliation: Environmental Science Program, Mount Allison University , Sackville, New Brunswick , Canada.

ABSTRACT
Climate change over the last two centuries has been associated with significant shifts in diatom community structure in lakes from the high arctic to temperate latitudes. To test the hypotheses that recent climate warming selects for species of smaller size within communities and a decrease in the average size of species within populations, we quantified the size of individual diatom valves from 10 depths in a sediment core covering the last ∼200 years from a pristine subarctic lake. Over the last ∼200 years, changes in the relative abundance of species of different average size and changes in the average valve size of populations of species contribute equally to the changes in community size structure, but are often opposite in sign, compensating for one another and moderating temporal changes in community size structure. In the surface sediments that correspond to the recent decades when air temperatures have warmed, the mean size of valves in the diatom community has significantly decreased due to an increase in the proportion of smaller-sized planktonic diatom species.

No MeSH data available.


Related in: MedlinePlus

Size and shape of Aulacoseira valves.(A) Comparison of measurements of valve area (AM, µm2), (B) surface area (SA, µm2), and (C) volume (V, µm3) of Aulacoseira valves with the cross-sectional area (A, µm2) and (D) the major (diameter, W) and minor (mantle height, L) axes in valve view. Symbols for each species/variety are A. lirata var. biseriata, circle; A. lirata var. lirata, square; A. perglabra var. floriniae, diamond; A. perglabra var. perglabra, triangle.
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fig-2: Size and shape of Aulacoseira valves.(A) Comparison of measurements of valve area (AM, µm2), (B) surface area (SA, µm2), and (C) volume (V, µm3) of Aulacoseira valves with the cross-sectional area (A, µm2) and (D) the major (diameter, W) and minor (mantle height, L) axes in valve view. Symbols for each species/variety are A. lirata var. biseriata, circle; A. lirata var. lirata, square; A. perglabra var. floriniae, diamond; A. perglabra var. perglabra, triangle.

Mentions: The estimate of average size of the diatom community (A) is derived from measurements of the two-dimensional area (µm2) enclosed by the outline drawn around the images of intact valves. This measurement of valve area makes no assumptions about the unobserved 3rd dimension of the valves. The majority of small centric species were imaged in valve view, and therefore the estimated valve area does not include the mantle depth (the height of the valve surrounding the valve face). In contrast the dominant Aulacoseira species examined were imaged predominantly in girdle view and therefore the estimate of area includes the mantle height and the diameter of the valve. Consequently we are able to estimate the 3-dimensional shape for Aulacoseira, but only the 2-dimensional shape of the small centric species and the average size of diatoms making up the community assemblage. Our estimates of valve area (A) for Aulacoseira are positively correlated with our alternate estimate of valve area AM, our estimate of surface area SA, and our estimate of V for the dominant Aulacoseira spp. (Fig. 2). The area determined from the outline of the valves, A, is systematically smaller but linearly correlated with AM, since the rectangular shape implied by AM (length × width of the valves) includes extra area not included in the hand tracing of the valve perimeter that was used to estimate A (Fig. 2).


Community- and population-level changes in diatom size structure in a subarctic lake over the last two centuries.

Kerrigan EA, Irwin AJ, Finkel ZV - PeerJ (2015)

Size and shape of Aulacoseira valves.(A) Comparison of measurements of valve area (AM, µm2), (B) surface area (SA, µm2), and (C) volume (V, µm3) of Aulacoseira valves with the cross-sectional area (A, µm2) and (D) the major (diameter, W) and minor (mantle height, L) axes in valve view. Symbols for each species/variety are A. lirata var. biseriata, circle; A. lirata var. lirata, square; A. perglabra var. floriniae, diamond; A. perglabra var. perglabra, triangle.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493642&req=5

fig-2: Size and shape of Aulacoseira valves.(A) Comparison of measurements of valve area (AM, µm2), (B) surface area (SA, µm2), and (C) volume (V, µm3) of Aulacoseira valves with the cross-sectional area (A, µm2) and (D) the major (diameter, W) and minor (mantle height, L) axes in valve view. Symbols for each species/variety are A. lirata var. biseriata, circle; A. lirata var. lirata, square; A. perglabra var. floriniae, diamond; A. perglabra var. perglabra, triangle.
Mentions: The estimate of average size of the diatom community (A) is derived from measurements of the two-dimensional area (µm2) enclosed by the outline drawn around the images of intact valves. This measurement of valve area makes no assumptions about the unobserved 3rd dimension of the valves. The majority of small centric species were imaged in valve view, and therefore the estimated valve area does not include the mantle depth (the height of the valve surrounding the valve face). In contrast the dominant Aulacoseira species examined were imaged predominantly in girdle view and therefore the estimate of area includes the mantle height and the diameter of the valve. Consequently we are able to estimate the 3-dimensional shape for Aulacoseira, but only the 2-dimensional shape of the small centric species and the average size of diatoms making up the community assemblage. Our estimates of valve area (A) for Aulacoseira are positively correlated with our alternate estimate of valve area AM, our estimate of surface area SA, and our estimate of V for the dominant Aulacoseira spp. (Fig. 2). The area determined from the outline of the valves, A, is systematically smaller but linearly correlated with AM, since the rectangular shape implied by AM (length × width of the valves) includes extra area not included in the hand tracing of the valve perimeter that was used to estimate A (Fig. 2).

Bottom Line: Climate change over the last two centuries has been associated with significant shifts in diatom community structure in lakes from the high arctic to temperate latitudes.To test the hypotheses that recent climate warming selects for species of smaller size within communities and a decrease in the average size of species within populations, we quantified the size of individual diatom valves from 10 depths in a sediment core covering the last ∼200 years from a pristine subarctic lake.In the surface sediments that correspond to the recent decades when air temperatures have warmed, the mean size of valves in the diatom community has significantly decreased due to an increase in the proportion of smaller-sized planktonic diatom species.

View Article: PubMed Central - HTML - PubMed

Affiliation: Environmental Science Program, Mount Allison University , Sackville, New Brunswick , Canada.

ABSTRACT
Climate change over the last two centuries has been associated with significant shifts in diatom community structure in lakes from the high arctic to temperate latitudes. To test the hypotheses that recent climate warming selects for species of smaller size within communities and a decrease in the average size of species within populations, we quantified the size of individual diatom valves from 10 depths in a sediment core covering the last ∼200 years from a pristine subarctic lake. Over the last ∼200 years, changes in the relative abundance of species of different average size and changes in the average valve size of populations of species contribute equally to the changes in community size structure, but are often opposite in sign, compensating for one another and moderating temporal changes in community size structure. In the surface sediments that correspond to the recent decades when air temperatures have warmed, the mean size of valves in the diatom community has significantly decreased due to an increase in the proportion of smaller-sized planktonic diatom species.

No MeSH data available.


Related in: MedlinePlus