Expansion kinematics are an intrinsic property of leaf development and are scaled from cell to leaf level at different nutrient availabilities

Leaves of Nicotiana tobacum L. and Ricinus communis L. develop with a wide range of different final sizes due to leaf position and nutrient availability. The aim of this study was to investigate, on different organizational levels of leaf growth, which parameters are affected by external nutrient availability and which parameters are not affected and might thus be intrinsic, general patterns of growth that govern plant architecture. We found that leaf size and final cell size was larger with higher external nutrient availability, and that hexose concentrations in N. tabacum were lower with higher nutrient availability. Despite these differences, several dynamic parameters of leaf development were not affected by the nutrient treatment. Leaves of all sizes within a species exhibited the same relationship between relative leaf growth rate and relative leaf area (RLA), which is defined as the ratio of momentary and final leaf area. External nutrient availability did not affect chlorophyll concentration per parenchyma cell, which increased linearly with leaf development. Leaves of identical RLA exhibited identical cell density patterns within their interveinal tissue layers. This indicates a close connection between the kinematics of cell expansion and RLA and, hence, reveals that kinematics are an intrinsic property of growing leaves that can be scaled from the cell to the leaf level

Near-future ocean warming and acidification alter foraging behaviour, locomotion, and metabolic rate in a keystone marine mollusc

Environmentally-induced changes in fitness are mediated by direct effects on physiology and behaviour, which are tightly linked. We investigated how predicted ocean warming (OW) and acidification (OA) affect key ecological behaviours (locomotion speed and foraging success) and metabolic rate of a keystone marine mollusc, the sea hare Stylocheilus striatus, a specialist grazer of the toxic cyanobacterium Lyngbya majuscula. We acclimated sea hares to OW and/or OA across three developmental stages (metamorphic, juvenile, and adult) or as adults only, and compare these to sea hares maintained under current-day conditions. Generally, locomotion speed and time to locate food were reduced ~1.5- to 2-fold when the stressors (OW or OA) were experienced in isolation, but reduced ~3-fold when combined. Decision-making was also severely altered, with correct foraging choice nearly 40% lower under combined stressors. Metabolic rate appeared to acclimate to the stressors in isolation, but was significantly elevated under combined stressors. Overall, sea hares that developed under OW and/or OA exhibited a less severe impact, indicating beneficial phenotypic plasticity. Reduced foraging success coupled with increased metabolic demands may impact fitness in this species and highlight potentially large ecological consequences under unabated OW and OA, namely in regulating toxic cyanobacteria blooms on coral reefs