Search results for "Esocidae"
showing 9 items of 9 documents
European catfish (Silurus glanis) as a freshwater apex predator drives ecosystem via its diet adaptability
2017
AbstractApex predators play a key role in ecosystem stability across environments but their numbers in general are decreasing. By contrast, European catfish (Silurus glanis), the European freshwater apex predator, is on the increase. However, studies concerning apex predators in freshwaters are scarce in comparison to those in terrestrial and marine ecosystems. The present study combines stomach content and stable isotope analyses with diet preferences of catfish to reveal its impact on the ecosystem since stocking. Catfish niche width is extremely wide in comparison to the typical model predator, Northern pike (Esox lucius). Catfish and pike have different individual dietary specialization…
A field methodology to study effects of UV radiation on fish larvae.
2003
There is a considerable lack of in situ specific information about the effects of UV-B radiation on limnic animals studied in the field. We exposed larval pike (Esox lucius L.) in two types of cuvettes (glass and quartz) placed at different depths (5 or 15 cm) to natural solar UV or to artificially enhanced UV-B (lamps on 3 h per day), simulating the scenarios for coming decades. Dose realism and comparability with earlier laboratory experiments was the main purpose, and therefore UV-B irradiances to the surface as well as underwater irradiances were directly measured. Result showed that UV-B dose rates in natural waters are low even though DOC concentration was low (4.8 mg/l) in our study …
Contrasting structural complexity differentiate hunting strategy in an ambush apex predator.
2021
AbstractStructural complexity is known to influence prey behaviour, mortality and population structure, but the effects on predators have received less attention. We tested whether contrasting structural complexity in two newly colonised lakes (low structural complexity lake—LSC; high structural complexity—HSC) was associated with contrasting behaviour in an aquatic apex predator, Northern pike (Esox lucius; hereafter pike) present in the lakes. Behaviour of pike was studied with whole-lake acoustic telemetry tracking, supplemented by stable isotope analysis of pike prey utilization and survey fishing data on the prey fish community. Pike displayed increased activity, space use, individual …
Impacts of piscicide-induced fish removal on resource use and trophic diversity of lake invertebrates
2022
Chemical eradication of non-native species has become a widely used method to mitigate the potential negative im- pacts of altered competitive or predatory dynamics on biodiversity and natural ecosystem processes. However, the re- sponses of non-target species can vary from rapid full recovery to delayed or absent recolonization, and little is known about the potential shifts in resource use and trophic diversity of native species following chemical treatments. We used a before-after-control-impact approach to study the effects of rotenone piscicide treatment on abundance and tro- phic niche of benthic invertebrates in three untreated and three treated lakes in central Norway, the latter gr…
Metals and Organochlorine Compounds in Fish from Latvian Lakes
1998
Organochlorines and metals have high toxicity and worldwide distribution in the aquatic environment. They are known to accumulate in sediments. In mollusks and fishes, they are bioconcentrated, even when released in minute quantities into the environment. This is important, as these chemicals have an adverse impact on species diversity, and accumulate in humans when seafood is consumed (Jaffar et al. 1988; Ruiter 1995). The nature and extent of accumulation and impact of persistent xenobiotics in water bodies depend on their sources; i.e. whether they are from industry, agricultural activities, transboundary transport with air masses (Sharif et al. 1993), geochemically determined elevated c…
Notes on the Biology and Ecology of Opeatogenys gracilis (Canestrini 1864) (Pisces: Gobiesocidae) from Coastal Environments in Sicily (Mediterranean)
2001
A particularly large number of specimens of the Mediterranean coastal fish Opeatogenys gracilis (Canestrini 1864) (Pisces: Gobiesocidae) were collected from Posidonia oceanica mats of the “Stagnone di Marsala” sound (western Sicily) and in the Gulf of Carini (northern Sicily). A study was made of biometric and meristic characters and, for the first time for this species, diet composition. The biometric and meristic data did not distinguish between specimens from the two study sites. In accordance with its benthic habit, O. gracilis feeds on small phytal prey living on Posidonia oceanica leaves. The preferential food items throughout the year were Copepoda Harpacticoida.
Between-population Similarity in Intestinal Parasite Community Structure of Pike (Esox Lucius)—Effects of Distance and Historical Connections
2009
The effect of geographical distance on similarity in parasite communities of freshwater fish has received considerable attention in recent years, and it has become evident that these apparently simple relationships are influenced by, among other things, colonization ability of parasites and degree of connectivity between the populations. In the present paper, we explored qualitative and quantitative similarity in the intestinal parasite communities of pike (Esox lucius) in a particular system where previously interconnected groups of lakes became isolated ca. 8,400 yr ago. Contrary to our expectations, we did not find differences in similarity between the lake groups or a negative effect of…
High sensitivity of northern pike larvae to UV-B but no UV-photoinduced toxicity of retene
2003
In order to investigate whether increased UV-B radiation is a risk factor, a series of acute laboratory experiments was conducted with larval stages of the northern pike (Esox lucius L.), hatching in Nordic waters in May. Further, a comparative investigation on the acute phototoxicity of retene (7-isopropyl-1-methylphenanthrene), a PAH compound recently revealed to posses UV-B-induced phototoxicity in larval coregonids, was conducted with pike larvae. In semi-static experiment, larvae were pre-exposed to retene (3, 9, 30 and 82 microg/g), with relevant controls, for 24 h and then irradiated for 3 h once a day (two consecutive days) with three UV-B doses (CIE-weighted 1.0, 1.8 or 2.7 kJ/m2 p…
UV-B exposure causes DNA damage and changes in protein expression in northern pike (Esox lucius) posthatched embryos.
2012
The ongoing anthropogenically caused ozone depletion and climate change has increased the amount of biologically harmful UV-B radiation, which is detrimental to fish in embryonal stages. The effects of UV-B radiation on the levels and locations of DNA damage manifested as cyclobutane pyrimidine dimers (CPDs), heat shock protein 70 (HSP70) and p53 protein in newly hatched embryos of pike were examined. Pike larvae were exposed in the laboratory to current and enhanced doses of UV-B radiation. UV-B exposure caused the formation of CPDs in a fluence rate-dependent manner, and the CPDs were found deeper in the tissues with increasing fluence rates. UV-B radiation induced HSP70 in epidermis, and…