Search results for "Lampetra"

Selection of spawning substratum by European river lampreys (Lampetra fluviatilis) in experimental tanks

2014

The selection of spawning substratum by the river lamprey (Lampetra fluviatilis) was studied in two experimental tanks with different flow conditions. In both tanks, four gravel sizes mixed with 15% sand were available to the test animals. In the tank with the lower current speed, lampreys selected in favour of the finest (2–8 mm) gravel size available against gravel sizes 4–20 mm and 8–40 mm. Selection was also significantly different in the tank with higher current speed where selection against the medium-sized substratum (4–20 mm) was evident, but there were no differences between selection for gravel sizes 2–8 mm, 2–40 mm and 8–40 mm relative to availability. Substratum selection and ob…

Lotic life stages of the European river lamprey (Lampetra fluviatilis) : anthropogenic detriment and rehabilitation

2015

Latvijas ūdeņu vides pētījumu un aizsardzība: referātu tēžu krājums (Rīga, 2020.gada 24. janvāris)

2020

Lipid-related thiamine deficiency cause mortality of river lampreys (Lampetra fluviatilis) during pre-spawning fasting

2023

Publisher Copyright: © 2023 The Authors River lampreys (Lampetra fluviatilis) were caught in the fall 2014 on entering the River Perhonjoki for spawning and kept at a hatchery until spawning in late spring 2015 to produce larvae for compensatory stockings. Since the lampreys died massively from early February onwards, they were investigated in March and May to clarify the cause of the deaths. The symptoms in lampreys resembled those of lipid-related thiamine (vitamin B1) deficiency of salmonines, called the M74 syndrome in the Baltic Sea area. Because the lipid content of lampreys was known to be high, thiamine concentrations were analyzed in the liver and ovulated unfertilized eggs, and th…

Vitellogenin from female and estradiol-stimulated male river lampreys (Lampetra fluviatilis L.)

2001

The influence of estradiol-17β (E2) on vitellogenesis is well documented for a number of oviparous craniates. We have examined the role that estradiol-17β plays in the induction and regulation of vitellogenin synthesis in the maturing European river lamprey, Lampetra fluviatilis. In both females and males the estradiol-17β concentrations in the plasma reached comparable maximum values in March, only a few weeks before spawning. Throughout the spawning run, the vitellogenin titer in the blood of females remains rather constant while the ovary volume increases. In contrast, we never found circulating VTG in untreated male lampreys. The synthesis and secretion of the yolk precursor molecule ca…

Makrozoobentosa indikatorgrupas upes nēģa Lampetra fluviatilis apdzīvotajās vietās

2020

Upes nēģis Latvijā vairāk kā 50% ikgadējās iekšzemes nozvejas, tomēr tam ir piešķirts īpaši aizsargājamās ierobežoti izmantojamās sugas statuss. Jau kopš 20. gs. vidus tiek veikti upes nēģu populāciju papildinoši pasākumi – vaislinieku pārcelšana pāri migrācijas šķēršļiem un mākslīgi pavairotu kāpuru izlaišana. Pasākumi tiek veikti upēs ar jau eksistējošu populāciju tās papildināšanas nolūkos, vai upes posmos, kuru izvēle veikta pēc virspusēja ekoloģiskā novērtējuma. Lai populācijas papildināšanas pasākumi būtu efektīvāki, nepieciešams izlaišanas vietas izvēlēties pēc vairākiem rādītājiem. Makrozoobentoss bieži tiek izmantots kā bioloģiskais indikators ūdenstilpju kvalitātes novērtēšanā. Šī…