Search results for "Aquatic ecology"
showing 4 items of 24 documents
The phenology of submerged macrophytes from Mediterranean wetlands as a sentinel of climate change = La fenologia dels macròfits submergits d'aiguamo…
2018
L’estudi de la fenologia, i.e. la temporització dels esdeveniments biològics recurrents, s’està usant per detectar els efectes del canvi climàtic sobre els organismes. Encara que els macròfits submergits exerceixen una funció clau en l’estructuració dels ecosistemes soms, hi ha poca informació sobre la seua fenologia. Aquesta tesi presenta les primeres dades (de 2014 a 2016) d’un esperable estudi a llarg termini. Els objectius principals son (i) establir la base metodològica per a l’estudi fenològic dels macròfits submergits, (ii) descriure la fenologia reproductiva de 6 espècies (Chara hispida, C. aspera, C. canescens, Nitella hyalina, Stuckenia pectinata i Utricularia australis) en dos ll…
Natural isotopes support groundwater origin as a driver of mire type and biodiversity in Slitere National Park, Latvia
2020
Slitere National Park in Latvia is home to rich fens with many endangered and threatened plant species. This study aims to address how the hydrological systems affect vegetation biodiversity (cf. Wolejko et al. 2019) in the mire systems of the National Park: the base-rich inter-dune mires and extremely base-rich calcareous fens. Groundwater samples from these areas were collected for measurements of ion composition and natural isotopes of C, H and O. Also, we simulated groundwater flow paths from the highest local topographical point (a nearby sandy plateau) to the sea, and calculated the residence times of these groundwater flows. The results show that the inter-dune mires are supplied by …
Temperature effects explain continental scale distribution of cyanobacterial toxins
2018
Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect…
Inferring Phytoplankton, Terrestrial Plant and Bacteria Bulk δ¹³C Values from Compound Specific Analyses of Lipids and Fatty Acids.
2015
Stable isotope mixing models in aquatic ecology require δ13C values for food web end members such as phytoplankton and bacteria, however it is rarely possible to measure these directly. Hence there is a critical need for improved methods for estimating the δ13C ratios of phytoplankton, bacteria and terrestrial detritus from within mixed seston. We determined the δ13C values of lipids, phospholipids and biomarker fatty acids and used these to calculate isotopic differences compared to the whole-cell δ13C values for eight phytoplankton classes, five bacterial taxa, and three types of terrestrial organic matter (two trees and one grass). The lipid content was higher amongst the phytoplankton (…