Search results for "Zooplankton"

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…

Terrestrial carbohydrates support freshwater zooplankton during phytoplankton deficiency

2016

Article

Long-term changes in pigmentation of arctic Daphnia provide potential for reconstructing aquatic UV exposure

2016

Abstract Despite the biologically damaging impacts of solar ultraviolet radiation (UV) in nature, little is known about its natural variability, forcing mechanisms, and long-term effects on ecosystems and organisms. Arctic zooplankton, for example the aquatic keystone genus Daphnia (Crustacea, Cladocera) responds to biologically damaging UV by utilizing photoprotective strategies, including pigmentation. We examined the preservation and content of UV-screening pigments in fossil Daphnia remains (ephippia) in two arctic lake sediment cores from Cornwallis Island (Lake R1), Canada, and Spitsbergen (Lake Fugledammen), Svalbard. The aims were to document changes in the degree of UV-protective p…

Phosphorus limitation enhances parasite impact: feedback effects at the population level

2014

Background Nutrient deficiency affects the growth and population dynamics of consumers. Endoparasites can be seen as consumers that drain carbon (C) or energy from their host while simultaneously competing for limiting resources such as phosphorus (P). Depending on the relative demands of the host and the parasite for the limiting nutrient, intensified resource competition under nutrient limitation can either reduce the parasite’s effect on the host or further reduce the fitness of the nutrient-limited host. So far, knowledge of how nutrient limitation affects parasite performance at the host population level and how this affects the host populations is limited. Results We followed the popu…

Oxidative stress biomarkers in the copepod Limnocalanus macrurus from the northern Baltic Sea : effects of hydrographic factors and chemical contamin…

2015

Inferring phytoplankton community composition with a fatty acid mixing model

2015

Abstract. The taxon specificity of fatty acid composition in algal classes suggests that fatty acids could be used as chemotaxonomic markers for phytoplankton composition. The applicability of phospholipid-derived fatty acids as chemotaxonomic markers for phytoplankton composition was evaluated by using a Bayesian fatty acid-based mixing model. Fatty acid profiles from monocultures of chlorophytes, cyanobacteria, diatoms, euglenoids, dinoflagellates, raphidophyte, cryptophytes and chrysophytes were used as a reference library to infer phytoplankton community composition in five moderately humic, large boreal lakes in three different seasons (spring, summer and fall). The phytoplankton commu…

Water chemistry, zooplankton and benthos in small lakes within the distribution area of the rare European pool frog Pelophylax lessonae (Camerano) in…

2020

Summary In June 2018, water chemistry, benthos and zooplankton were investigated in 7 small lakes/ ponds within the key area of the European pool frog Pelophylax lessonae (Camerano) in Norway. The geographic distribution of the Norwegian population is minor, limited to a very few small lakes in the county of Agder in southernmost Norway. Since the species is thermophilic, reproduction success only occurs in warm summers. Accordingly, the pool frog is one of the most rare vertebrates in Norwegian fauna, classified as critically endangered in the Norwegian red list. A breeding program is today established in order to rescue this species.The article deals with potential biotope challenges most…

Limnological aspects of sicilian reservoirs: A comparative, ecosystemic approach

1999

This paper is a report on the state-of-the-art of reservoir limnology in Sicily, the largest island of the Mediterranean Sea. The territory is characterised by a semi-arid climate with a dry and a wet semester occurring in the year. Evaporative losses are strong during the summer and, on an annual basis, they often exceed precipitation. Thus, reservoirs constitute an important water resource for the island to supply drinking water and to provide for agricultural needs in the periods of drought. However, despite their importance, they receive poor attention from the scientific and political communities and in the absence of any environmental policy or suitable territorial planning, their wat…

The importance of phytoplankton production for carbon budgets in a semiarid floodplain wetland

2011

Phytoplankton production (PP) in wetlands is not measured as often as that of macrophytes. A three year-study during a period of sustained high flooding was undertaken in a central Spanish floodplain wetland (Las Tablas de Daimiel National Park) to determine net PP, its spatial heterogeneity and controlling factors, and compare it with primary production in macrophyte communities. This enabled us to estimate carbon budgets for each community. All PP variables showed high spatial and temporal variability among sites, resulting in low coherence even when flooding connected all sites. Net PP corresponded to 25- 36% of submerged plant production and 3-10% of helophyte production. Net PP was con…

Ecological and evolutionary impact of diapause on zooplankton

2012

La diapausa es un tipo de dormición que permite a los organismos sobrevivir a periodos ambientales desfavorables y lidiar con la impredicibilidad del hábitat. La producción de huevos diapáusicos es especialmente común en especies de invertebrados acuáticos como ostrácodos, anostráceos, notostráceos, copépodos, cladóceros o rotíferos. La presente tesis profundiza en el estudio de las implicaciones ecológicas y evolutivas de la diapausa tanto a nivel poblacional, como a nivel de comunidad. A nivel poblacional, se estudia el impacto de los bancos de huevos sobre la diferenciación genética poblacional y su relación con el flujo génico, la deriva genética y los efectos fundadores persistentes. L…