Long-term Changes in the Ichthyofauna of Latvia's Inland Waters

Riga, Aleksejevs, E., Latvian Fish Resources Agency,; Birzaks, Janis

doi:10.2478/v10145-011-0022-2

Cited by 8 publications

(5 citation statements)

References 1 publication

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“…In Estonia, the species is listed as EN (Lilleleht, ). In more southern areas around the Baltic Sea the situation is more positive with stable or increasing populations, although it may be difficult to separate effects of natural processes from past stocking programmes (Aleksejevs & Birzaks, ). In parts of Germany, the number of wels has even increased to such a degree that the species is presently regarded as a pest; moreover, illegal introductions across southern and western Europe have in recent time greatly increased the number of invasive populations (Cucherousset et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Reduced genetic diversity and low effective size in peripheral northern European catfish Silurus glanis populations

Palm

Vinterstare

Nathanson

et al. 2019

Journal of Fish Biology

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Using 10 polymorphic microsatellites and 1251 individual samples (some dating back to the early 1980s), genetic structure and effective population size in all native and introduced Swedish populations of the European wels catfish or Silurus glanis were studied. Levels of genetic variability and phylogeographic relationships were compared with data from a previous study of populations in other parts of Europe. The genetically distinct Swedish populations displayed comparably low levels of genetic variability and according to one-sample estimates based on linkage disequilibrium and sib ship-reconstruction, current local effective population sizes were lower than minimum levels recommended for short-term genetic conservation. In line with a previous suggestion of postglacial colonisation from a single refugium, all Swedish populations were assembled on a common branch in a star-shaped dendrogram together with other European populations. Two distinct subpopulations were detected in upper and lower habitats of River Emån, indicating that even minor dispersal barriers may restrict gene flow for wels in running waters. Genetic assignment of specimens encountered in the brackish Baltic Sea and in lakes where the species does not occur naturally indicated presence of long-distance sea dispersal and confirmed unauthorised translocations, respectively.

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Section: Introductionmentioning

confidence: 99%

Reduced genetic diversity and low effective size in peripheral northern European catfish Silurus glanis populations

Palm

Vinterstare

Nathanson

et al. 2019

Journal of Fish Biology

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“…If the sediments are polluted, toxic chemicals such as heavy metals and other pollutants can release back into the water. In addition to changes of water flow, also impact to the fish fauna can be observed, in deeper lakes the area is more accessible to larger predators, not only small fish [22].…”

Section: Resultsmentioning

confidence: 99%

Composition and Quality of Freshwater Lake Sediments (Balvu and Pērkonu Lakes)

Purmalis

Kļaviņš

Arbidans

2019

ETR

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Water quality, watershed basin and urbanization are key factors from the perspective of freshwater management; however, actual depth of waterbodies is often an overlooked element. Actual depth represents the overall depth of lake bed and depth of sediments. Some cases have been reported, where with increase of average depth of lake, it is possible to expect improvements of water quality when sediments are removed. If lakes are eutrophic, shallow, overgrown with macrophytes and contain high concentrations of biogenic elements water and lake ecosystem quality can be endangered. Removal of sediments can be an expensive procedure and also depends on the composition, structure, local conditions and total amount of sediments, also the disposal or possible use of sediments must be considered. Therefore, it is crucial to understand not only the genesis of sediments, but also possible pollutants, especially in urban territories. Two lakes in Latvia, where the coastal areas of lakes are urbanized at different levels, were studied. Lake Pērkonu was less affected from urbanization than Lake Balvu, cumulative effects of sedimentation and eutrophication were shown as these two lakes are interconnected. Characterization of lake sediments was done, including measurements of pH, ash content, analysis of C/N ratio, biological composition, metals, polyaromatic hydrocarbons (PAH), content of organic matter and concentration of humic acids. Results show that structure and composition of sediments in studied lakes differ with increasing depth, giving opportunity to track environmental changes in the past and differentiate possible applications of sediments. In deeper layers sediments were mostly formed from algae, but in more recent stages of lake development macrophytes were more dominant. Sediments formed after Ice-Age and located close to the bottom of the lake differ from conditions on paste (relief of lake bed, streams etc.), because areas with accumulated clay material and areas with sandy material were present.

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“…Studies in Latvia showed that the distribution and abundance of cold-and warm-water FWsp have changed from the Palaeolithic to the present, with a general increase in the distribution of some warmwater species (Sloka 1970, 1988, Aleksejevs & Birzaks 2011). Climate change is apparently linked to the periodical mass die-off of cold-water species in Latvian lakes and changes in the migration patterns of diadromous species in rivers (Aleksejevs & Birzaks 2011, Aleksejevs & Birzaks 2012, Birzaks 2020). In the past, species adapted to climate change by shifting their distribution to colonize suitable habitats.…”

Section: Discussionmentioning

confidence: 99%

The Importance of Natura 2000 Sites and Their Management for the Conservation of Freshwater Fish, Lamprey and Crayfish in Latvia

Birzaks,

Nitcis

2023

ABUD

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Natura 2000 protected areas have been considered the most important instruments for biodiversity conservation in the European Union intended for the protection of species and habitats. In Latvia, they have not originally been established to protect freshwater species and their habitats, so the effectiveness of their protection is still unclear, influenced by past and current anthropogenic alterations and their consequences. We assessed and discussed 1) species occurrence and protected habitat rate by Natura 2000 sites and outside them; 2) species diversity Natura 2000 by their size and landscape complexity; 3) the main anthropogenic pressures and options for reducing them; 4) opportunities to improve the Natura 2000 management. For the first time in Latvia, 46 fish, lamprey and crayfish species (in total 1962 records) have been compiled, based on UTM 1x1 km grid cells. The analysis shows that Natura 2000 sites, which cover only 11 % of the country's land area, contain all the species identified in the studies and most of the country's freshwater habitats. This suggests that the Natura 2000 network in Latvia is sufficient to protect species and their habitats in their current state. However, this can be improved by addressing gaps in fish, lamprey and crayfish species management plans and making them more relevant to current challenges such as river network fragmentation, the spread of invasive species, and climate change.

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Long-term Changes in the Ichthyofauna of Latvia's Inland Waters

Cited by 8 publications

References 1 publication

Reduced genetic diversity and low effective size in peripheral northern European catfish Silurus glanis populations

Reduced genetic diversity and low effective size in peripheral northern European catfish Silurus glanis populations

Composition and Quality of Freshwater Lake Sediments (Balvu and Pērkonu Lakes)

The Importance of Natura 2000 Sites and Their Management for the Conservation of Freshwater Fish, Lamprey and Crayfish in Latvia

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