Search results for "eutrophication"
showing 8 items of 188 documents
Increasing temperature and productivity change biomass, trophic pyramids and community‐level omega‐3 fatty acid content in subarctic lake food webs
2021
Climate change in the Arctic is outpacing the global average and land-use is intensifying due to exploitation of previously inaccessible or unprofitable natural resources. A comprehensive understanding of how the joint effects of changing climate and productivity modify lake food web structure, biomass, trophic pyramid shape and abundance of physiologically essential biomolecules (omega-3 fatty acids) in the biotic community is lacking. We conducted a space-for-time study in 20 subarctic lakes spanning a climatic (+3.2 degrees C and precipitation: +30%) and chemical (dissolved organic carbon: +10 mg/L, total phosphorus: +45 mu g/L and total nitrogen: +1,000 mu g/L) gradient to test how temp…
Macroalgal responses to ocean acidification depend on nutrient and light levels
2015
Ocean acidification may benefit algae that are able to capitalize on increased carbon availability for photosynthesis, but it is expected to have adverse effects on calcified algae through dissolution. Shifts in dominance between primary producers will have knock-on effects on marine ecosystems and will likely vary regionally, depending on factors such as irradiance (light vs. shade) and nutrient levels (oligotrophic vs. eutrophic). Thus experiments are needed to evaluate interactive effects of combined stressors in the field. In this study, we investigated the physiological responses of macroalgae near a CO2 seep in oligotrophic waters off Vulcano (Italy). The algae were incubated in situ …
Turve- ja metsätalouden vaikutukset kahden metsäjärven surviaissääskiyhteisöihin : paleolimnologinen tutkimus
2015
Tutkielmassa selvitettiin turve- ja metsätalouden vaikutuksia Martinjärven ja Iso Kivijärven surviaissääskiyhteisöihin paleolimnologisen menetelmän avulla. Järvien sedimenttiprofiileita tarkasteltiin viimeisen 400 vuoden ajalta. Järvet ovat pieniä, matalia humusjärviä ja sijaitsevat Keski-Suomessa Keuruulla vierekkäisillä valuma-alueilla. Surviaissääskiyhteisöjen muutosten perusteella tutkittiin järvien rehevyystason ja humoosisuuden muutoksia ennen ja jälkeen metsätalouden ja turvetuotannon aloittamista. Soiden laajamittainen ojitus metsätalouden käyttöön alkoi 1960-luvulla molempien järvien valuma-alueilla. Martinjärven valuma-alueella aloitettiin lisäksi turpee…
Determination of Changes in the Quality of Surface Water in the River—Reservoir System
2021
Assessing the changing parameters of water quality at different points in the river–reservoir system can help prevent river pollution and implement remedial policies. It is also crucial in modeling water resources. Multivariate statistical analysis is useful for the analysis of changes in surface water quality. It helps to identify indicators that may be responsible for the eutrophication process of a reservoir. Additionally, the analysis of the water quality profile and the water quality index (WQI) is useful in assessing water pollution. These tools can support and verify the results of a multivariate statistical analysis. In this study, changes in water quality parameters of the Turawa r…
Current status and development of sanitation and wastewater treatment in the national and international context
2012
El acceso al saneamiento y depuración de aguas residuales es un aspecto de suma importancia tanto desde el punto de vista ambiental como sanitario. Por ello, desde el Imperio Mesopotámico hasta la actualidad se han producido importantes avances en esta materia. Sin embargo, en la actualidad, en la mayoría de los países en vías de desarrollo el acceso al saneamiento continua siendo deficitario. Por otra parte, los países desarrollados, que sí disponen de sistemas adecuados de depuración de aguas residuales, se enfrentan al reto de mejorar la sostenibilidad de estos sistemas. En este trabajo se describe en profundidad el estado actual y evolución en el tiempo del saneamiento y depuración de a…
The adaptations to tube-dwelling life of Propsilocerus akamusi (Diptera: Chironomidae) larvae and its eutrophication-tolerant mechanisms
2019
Propsilocerus akamusi (Diptera: Chironomidae) is a dominant macroinvertebrate species in many eutrophic lakes in subtropical and temperate zones. P. akamusi larvae can migrate deep into the sediment (>30 cm) during summer where is no oxygen. However, to our knowledge, the specific adaptive tactics of its tube-dwelling life (>30 cm) and underlying mechanisms why this species is favored by nutrient-rich lakes remain limited. With the understanding above-mentioned issues, we can provide important information for the development of sensitive biomonitoring. We examined monthly morphological dynamics and physiological adaptations of P. akamusi to anoxic conditions, and environmental relationships…
Hydrogen isotopes (δ2H) of polyunsaturated fatty acids track bioconversion by zooplankton
2022
1. Organisms at the base of aquatic food webs synthesize essential nutrients, such as omega-3 polyunsaturated fatty acids (n-3 PUFA), which are transferred to consumers at higher trophic levels. Many consumers, requiring n-3 long-chain (LC) PUFA, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have limited ability to biosynthesize them from the essential dietary precursor α-linolenic acid (ALA) and thus rely on dietary provision of LC-PUFA. 2. We investigated LC-PUFA metabolism in freshwater zooplankton using stable hydrogen isotopes (δ2H) of fatty acids as tracers. We conducted feeding experiments with the freshwater keystone grazer Daphnia to quantify changes in the δ2…
Browning-induced changes in trophic functioning of planktonic food webs in temperate and boreal lakes: insights from fatty acids
2022
AbstractThe effects of lake browning on trophic functioning of planktonic food webs are not fully understood. We studied the effects of browning on the response patterns of polyunsaturated fatty acids and n−3/n−6 ratio in seston and compared them between boreal and temperate lakes. We also compared the regional differences and the effects of lake browning on the reliance of zooplankton on heterotrophic microbial pathways and the mass fractions of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in zooplankton. Lake browning was associated with increasing phytoplankton biomass and concentrations of EPA and DHA in both temperate and boreal lakes, but the seston n−3/n−6 ratio was low…