A liquid leaf and its SV allometry

The objective of our study was to compare surface-to-volume (SV) allometries of natural water bodies and of the living systems inhabiting them. Recently, the most general and frequently discussed biological regression equations (allometries) were used to relate the basic traits of a living organism [metabolic expenditures, respiration (R)] with its body mass (W). The most frequent slope estimate of this allometry is ~0.75. While the metabolic processes necessitate fluxes of numerous resources across the organism's external surface (Sm), the fractal geometry of living systems produces many various geometric shapes and slopes of the SV allometry. For the metabolic surface of plants (leaf area, Sm) versus body mass (W), the most general regression (from unicellular algae to aquatic macrophytes and largest terrestrial plants, W size range of 24 orders) produced a regression slope of 0.78; hence, the slope is very close to the above 0.75 estimate. Using a very broad range of water bodies (from a microbial vial to the world ocean, more than 100 objects) we have found an SV slope of 0.74. Hence, the two SV slopes - the global range of water bodies and the living systems inhabiting them - practically coincide. We think that this coincidence is important and deserves additional study.