A mathematical age structure model for dry matter production (photosynthesis) and allocation to plant parts in European grape (Vitis vinifera L.) is presented, and it is used to examine the priorities and allocation dynamics of photosynthate partitioning to respiration, reserves, leaf, stem and root tissues (i.e., vegetative), and fruit in four varieties. In the model, photosynthate is allocated first to respiration, then fruit and reserves, and lastly to vegetative growth, while the allocation rates are controlled by the ratio of photosynthate supply to the various demands at the successive priority levels. Maximum and minimum temperatures are used to compute physiological time and physiological age in the model (i.e., in degree days above 10 °C), while solar radiation (Jm−2 day−1) is used to compute the per unit leaf rate of photosynthesis. Extensive field data on dry matter allocation for the variety Chenin blanc were used to construct and validate the model, while smaller data sets were used to estimate parameters for three other varieties of grape. The model results simulate well the observed data.

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The European eel Anguilla anguilla is a critically endangered catadromous species. There is an urgent need for close surveillance of the populations that are still viable in European rivers. The species is difficult to observe in freshwater because of its bottom-dwelling behavior; the currently employed methods of eel monitoring in Europe based on the physical capture of individuals are stressful and may cause mortality. Here, we present a new highly sensitive method based on an A. anguilla-specific qPCR marker designed within the cytochrome oxidase I mitochondrial gene for application on environmental DNA (eDNA). Since the detectability of eDNA depends on the hydrographic conditions, we applied correction for altitude and a linear model and were able to predict the eel biomass from the eDNA in the different rivers of northern Spain still holding wild populations. The method was validated by electrofishing surveys. This novel eDNA-based marker allows for estimating the European eel biomass in running waters from small 1.5 L water samples and could complement, or replace in some cases, current eel surveys without disturbing wild populations.

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