Raw data obtained from stable isotope analysis of δ13C and δ15N in beaks of the squids Gonatus fabricii (Lichtenstein, 1818) and Todarodes sagittatus (Lamarck, 1798) (Cephalopoda: Oegopsida), and primary analyses of these data. Squids sampled in the Baffin Bay, Davis Strait and Nordic Seas (1882-2010) and Iceland, Faroe Islands and Ireland (1844-2023), respectively. The beaks either come from the squids caught as bycatch, or from natural history museums, from stomach contents of predators.
Stable isotope analysis (SIA) has emerged as a valuable tool for understanding the trophic structure of the marine food web and gaining insights into trophic levels and niche. Researchers are increasingly utilizing SIA in studies focused on feeding ecology, particularly in estimating the long-term diets of meso- and bathypelagic fish. To facilitate this research, a global database of published data on stable isotopes, specifically δ13C and δ15N, of meso- and bathypelagic fish was created. The database was constructed by conducting a thorough search on Google Scholar and reviewing the references cited in the retrieved papers. The search primarily involved using popular terms such as stable isotope analysis or feeding ecology in combination with mesopelagic or bathypelagic fish. The resulting SIA database contains δ13C and δ15N values for 95 different species of meso- and bathypelagic fish, belonging to 27 families, with specimens collected between 2004 and 2015. Each entry in the database includes information on the sampling location, month and year of sample collection, taxonomic classifications (phylum, class, order, family), number of samples analyzed, as well as the reference and DOI of the original data source. This global SIA database holds significant potential as a valuable tool and data source for conducting large-scale meta-analyses.
Sponge grounds are hotspots of biomass and biodiversity in the otherwise barren deep sea. It remains unknown how these ecosystems can thrive in such food limited environments, since organic matter settling from the surface ocean covers only small parts of their carbon demand. In this study, the food-web interactions and potential food sources of a North Atlantic deep-sea sponge reef were identified by bulk and compound-specific stable isotope analysis of amino and fatty acids. The elevated bulk δ15N values of sponges with relatively low abundance of associated microbes (LMA) is in line with a position at the top of the benthic food web, while the relatively high δ13C and intermediate δ15N values of high microbial abundance (HMA) sponges suggest considerable reliance on an alternate resource. Trophic positions based on amino acid δ15N values placed HMA sponges at the base of the food web. Fatty acid analysis of δ13C indicated transfer of sponge derived organic matter to the wider food web. Our results show that sponges drive both bottom-up and top-down processes, shunting organic carbon to higher trophic levels that would otherwise be inaccessible to other fauna. In this way, sponges are key to the sustenance of thriving deep-sea ecosystems.
With regard to climate-driven environmental changes in Europe during the next decades (heatwaves and extended drought periods) the understanding of how plants may adapt to these environmental constraints and ensure their survival awaits further attention. Moreover, besides well studied responses of plants to various drought intensities, the capacity of recovery from drought and its velocity and rate will become an important issue for plant species across Europe. As there is a scarcity of studies in the field of recovery from drought, this project is designed to unravel its underlying physiological processes by a systematic analysis of photosynthetic and respiratory traits of several Mediterranean species during recovery from various drought intensities. The time frame of drought within a vegetation period may additionally affect the capacity of drought tolerance and rate of recovery, as well as growth and survival. Main Results and Conclusions The rate of photosynthetic restoration after drought-induced suppression depends on the intensity of drought, as recovery of all examined plant species has always been more rapid after mild or moderate drought (one to three days) than after severe drought (more than three days). Differences appeared among species, as annual species (Nicotiana sylvestris, Glycine max) recovered more rapidly from severe drought than perennial ones (Vitis vinifery, Cistus albidus, Quercus ilex). However, perennials followed a more conservative strategy during drought progression by loosing less water than the annual plants (which reached severe stress more rapidly but recovered also quicker after the short drought period). Limitation of photosynthetic recovery during the re-watering phase was driven by a delayed stomatal opening and impaired internal CO2 diffusion, namely the mesophyll conductance (gm). The gm has been found to be an important factor in limiting photosynthesis during drought and after subsequent re-watering, which further supports the idea of an important role of gm in photosynthetic regulation during stress and the necessity of further studies on its regulation under climatic variables. The impact of other climatic variables than water stress on gm could be assumed by comparing tobacco plants under different growth conditions. Besides the role of gm, the interaction of photosynthesis and respiration during drought and recovery has been shown to be important and highly flexible, as impaired respiratory chain was overcome by enhanced cytochrome pathway activity and hence higher total respiration. This adjustment might help to match the cellular ATP demand and maintain the cell redox balance, thus resulting in a similar response of photosynthesis to drought and re-watering.