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Sirvi Autor "Haldna, Marina" järgi

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  • Pisipilt
    Kirje
    Do abundance and percentage of dipteran larvae and Oligochaeta indicate low water quality in streams and lake littoral?
    (Sciendo, 2019) Timm, Henn; Haldna, Marina; Centre for Limnology. Institute of Agricultural and Environmental Sciences
    The presence of chironomids and/or oligochaetes is generally considered to be an indication of poor status of freshwater. Non-chironomid dipterans show unclear trends. The abundance and percentage of these groups are rarely used as potential indicators. We attempted to determine whether these metrics reveal freshwater quality in lowland streams and lake littoral (Northern Europe, Baltic ecoregion, Estonia). The water quality was assessed based either on the water itself or on macroinvertebrates, fish, macrophytes, phytobenthos (in streams only) and/or phytoplankton (in lakes only). As expected, the high abundance and high percentage of chironomids and ceratopogonids indicated low quality of water in lakes. The high percentage of chironomids indicated low water quality also in streams. The high percentage of oligochaetes indicated low water quality in lakes. However, their high abundance (but not the percentage) was unexpectedly a symptom of high water quality in streams and to a lesser extent in lakes. In these cases, oligochaetes were represented by rheophilic, rather than saprophilic species. The abundance of simuliids (but not the percentage) and the richness of dipteran families indicated high water quality in streams. We suggest that the obtained results will allow better use of the indicative potential of freshwater macroinvertebrates.
  • Pisipilt
    Kirje
    Factors behind the variability of phosphorus accumulation in Finnish lakes
    (Springer, 2018) Tammeorg, Olga; Haldna, Marina; Nõges, Peeter; Appleby, Peter; Möls, Tõnu; Niemistö, Juha; Tammeorg, Priit; Horppila, Jukka; Centre for Limnology
    Purpose Phosphorus retention (TPacc) is one of the major water quality regulators in lakes. The current study aimed at ascer- taining the specific lake characteristics regulating TP acc . Moreover, we were interested whether NAO (North Atlantic Oscillation), a proxy of climatic forcing, can explain variability in TPacc, additionally to that ascribed to lake characteristics. Materials and methods Sediment cores were obtained from 21 Finnish lakes, subject to radiometric dating and measurements of TP concentrations. Principal components (PCs) were generated using lake characteristics that are usually included into the modelling of TPacc (e.g. lake area, lake depth, catchment area, P inflow) but also the parameters that the classical models usually missed (e.g. anoxic factor). We used significant principal components (PCs), specific combinations of lake characteristics and monthly NAO values as predictors of TPacc. Results and discussion Lake characteristics explained the bulk of TPacc variability. The most influential factors (positive drivers) behind TPacc included PC1 (representing mainly deep lakes), PC2 (small lakes with high levels of anoxia and water column stability), PC3 (productive lakes with large catchment area and short water residence time), PC4 (lakes with high water column stability, low anoxic factor and relatively high sediment focusing) and PC5 (lakes with high levels of P inflow, anoxia and long water residence time). Additionally, we found a potential negative effect of NAO in October on the annual TPacc. This NAO was significantly positively related to temperatures in surface and near-bottom water layer (also their difference) in autumn, suggest- ing the possible implications for the internal P dynamics. Increased mineralization of organic matter is the most likely explanation for the reduced TPacc associated with NAO-driven water temperature increase. Conclusions The analysis presented here contributes to the knowledge of the factors controlling P retention. Moreover, this spatially and temporally comprehensive sediment data can potentially be a valuable source for modelling climate change implications.
  • Pisipilt
    Kirje
    Ogakärblase Hermetia illucens vastsete kasutamine tarneahelast välja mineva kalajäätme taasutiliseerimiseks : projekt nr. 811019790010 : lõpparuanne
    (Eesti Maaülikool, 2021) Reissaar, Richard; Kosk, Sander; Silm, Maidu; Kriipsalu, Mait; Poolakese, Morten; Kisand, Anu; Piiroja, Jevgenia; Kade, Siiri; Haldna, Marina; Kruus, Maarja; Tõnurist, Kadi; Shanskiy, Merrit
    Käesolev projekt võtab vaatluse alla võimaluse töödelda kalatööstuse jääke putukate vastsete abil. Putukakasvatuse käigus on võimalus vabaneda kalatööstuses tekkivatest bioloogilistest jäätmetest ja toota neist potentsiaalset väärtuslikku loomasööta ja komposti. Projektis kasutatavaks putukaliigiks oli Hermetia illucens (inglise k. Black soldier fly), kes on maailmas kõige enam levinud tööstuslikult kasvatatav putukaliik. Antud projekt oli jaotatud neljaks suuremaks osaks, mis potentsiaalselt moodustavad ringmajandusliku terviku: 1. Populatsiooni suurendamine ja hoidmine suuremamahuliseks kasvatuseks 2. Vastsete toitmine kalatööstuse jäägiga laboratoorsetes tingimustes ja kaluri kodune vastsekasvatuse katse 3. Vastsete sõnnikust komposti tootmine 4. Taimede väetuskatsed vastsete sõnnikukompostiga Putukakasvatus on Eestis uudne ja potentsiaalne majandusharu, mida meil on vähe uuritud. Seetõttu oli tarvis sisse seada putukatööstuse võimaluste uurimiseks vajalikud ruumid ja infrastruktuur. Putukakasvatuseks loodi Eesti Maaülikooli Rakendusentomoloogia Praktikabaas, kus toimus projekti põhitegevus. Praktikabaas jätkab toimimist peale projekti lõppu. Projekti peamiseks eesmärgiks oli uurida, kuidas mõjutab kalajäätmete toitmine putukavastsetele nende toiteväärtuslikku koostist, putukasõnniku koostist ja putukasõnnikust toodetud komposti efektiivsust taimeväetisena. Lisaks toimus ka kaluri kodune vastsekasvatuse katse, kus kalur sai kodustes tingimustes kasvatada putukavastseid. Kaluri poolt kasvatatavate vastsetega teostati kanade söötmiskatse, mille käigus toideti kaluri poolt peetavatele kanadele projekti käigus toodetud putukavastseid. Kanadelt korjati mune, mis läksid sisendiks kanamunade degusteerimise katsesse. Katset kajastati Eesti Televisiooni telesaates Osoon. Putukavastsete sõnnikust toodeti komposti, millega teostati taimede väetuskatse. Projekti käigus hinnati erinevate söödaparalleelide ja söödakoostiste mõju putukasõnniku komposteerumisele. Taimede väetuskatsega hinnati putukasõnniku komposti efektiivsust bioloogilise väetisena.
  • Pisipilt
    Kirje
    Outcomes of the littoral monitoring of a large shallow lake: a case of Lake Peipsi : [presentation]
    (Estonian University of Life Sciences, 2023) Mäemets, Helle; Palmik-Das, Kadi; Haldna, Marina
    The presentation took place at the 11th International Shallow Lakes Conference.
  • Pisipilt
    Kirje
    Response of primary producers to water level fluctuations of Lake Peipsi
    (Estonian Academy Publishers, 2018) Mäemets, Helle; Laugaste, Reet; Palmik, Kadi; Haldna, Marina; Centre for Limnology. Institute of Agricultural and Environmental Sciences
    The amplitude of natural fluctuation between annual averages of the water level (WL) of Lake Peipsi (3555 km 2) is 1.5 m. A study aimed to examine the impact of WL fluctuations on phytoplankton, macrophytes, and their epiphyton was performed annually at littoral stations during 2005–2015. Also the characteristics of pelagic water were collated with the WL. Changes in littoral and pelagial phytoplankton were similar, with the exclusion of massive wind-caused accumulations of cyanobacteria in the littoral. At the lowest WL a significant increase occurred in (a) the biomass of phytoplankton and the share of phytoplankton-derived organic carbon in water and (b) the species richness and biomass of macrophytes, including submerged plants and macroalgae. The abundance of epiphytes did not reveal a clear relation with the WL. The ratios of biomasses in the years with the lowest and the highest average WL were 2.2 for Potamogeton spp. and 2.6 for phytoplankton. The assessment of ecological status at the minimum and the maximum WL differs at least by one quality class. Decisions about ecological status based on phytoplankton and large filamentous green algae at low water may be contrary to decisions based on macrophytes: high biomasses of phytoplankton and macroalgae indicate hypertrophic status, but species-rich macrovegetation and high biomasses of charophytes and elodeids are considered to be characteristic of meso- to eutrophic water bodies.