Size matters: relationships between body size and body mass of common coastal, aquatic invertebrates in the Baltic Sea

PeerJ

article

Johan Eklöf¹  Åsa Austin¹  Ulf Bergström²  Serena Donadi¹  Britas D.H.K. Eriksson⁴  Joakim Hansen³  Göran Sundblad⁵ 

[1] Department of Ecology, Environment and Plant Sciences ,(DEEP), Stockholm University;Department of Aquatic Resources, Swedish University of Agricultural Sciences;Baltic Sea Centre, Stockholm University;Groningen Institute for Evolutionary Life-Sciences GELIFES, University of Groningen;Aquabiota Water Research

关键词: Estuary;    Biometry;    Infauna;    Submerged aquatic vegetation;    Isometric scaling;    Length:weight relationship;    Epifauna;    Allometry;    Seagrass;    Weight;   

DOI  :  10.7717/peerj.2906

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

BackgroundOrganism biomass is one of the most important variables in ecological studies, making biomass estimations one of the most common laboratory tasks. Biomass of small macroinvertebrates is usually estimated as dry mass or ash-free dry mass (hereafter ‘DM’ vs. ‘AFDM’) per sample; a laborious and time consuming process, that often can be speeded up using easily measured and reliable proxy variables like body size or wet (fresh) mass. Another common way of estimating AFDM (one of the most accurate but also time-consuming estimates of biologically active tissue mass) is the use of AFDM/DM ratios as conversion factors. So far, however, these ratios typically ignore the possibility that the relative mass of biologically active vs. non-active support tissue (e.g., protective exoskeleton or shell)—and therefore, also AFDM/DM ratios—may change with body size, as previously shown for taxa like spiders, vertebrates and trees.Methods1 mm) in 32 shallow bays along a 360 km stretch of the Swedish coast along the Baltic Sea; one of the largest brackish water bodies on Earth. We then estimated statistical relationships between the body size (length or height in mm), body dry mass and ash-free dry mass for 14 of the most common taxa; five gastropods, three bivalves, three crustaceans and three insect larvae. Finally, we statistically estimated the potential influence of body size on the AFDM/DM ratio per taxon.ResultsFor most taxa, non-linear regression models describing the power relationship between body size and (i) DM and (ii) AFDM fit the data well (as indicated by low SE and high R2). Moreover, for more than half of the taxa studied (including the vast majority of the shelled molluscs), body size had a negative influence on organism AFDM/DM ratios.DiscussionThe good fit of the modelled power relationships suggests that the constants reported here can be used to quickly estimate organism dry- and ash-free dry mass based on body size, thereby freeing up considerable work resources. However, the considerable differences in constants between taxa emphasize the need for taxon-specific relationships, and the potential dangers associated with ignoring body size. The negative influence of body size on the AFDM/DM ratio found in a majority of the molluscs could be caused by increasingly thicker shells with organism age, and/or spawning-induced loss of biologically active tissue in adults. Consequently, future studies utilizing AFDM/DM (and presumably also AFDM/wet mass) ratios should carefully assess the potential influence of body size to ensure more reliable estimates of organism body mass.

【 授权许可】

CC BY