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Camilla Parzanini Michael T. Arts Mehis Rohtla Janet Koprivnikar Michael Power Anne Berit Skiftesvik Howard I. Browman Dino Milotic Caroline M. F. Durif 《Journal of fish biology》2021,99(3):1110-1124
Lipids, particularly fatty acids (FAs), are major sources of energy and nutrients in aquatic ecosystems and play key roles during vertebrate development. The European eel Anguilla anguilla goes through major biochemical and physiological changes throughout its lifecycle as it inhabits sea- (SW), and/or brackish- (BW) and/or freshwater (FW) habitats. With the ultimate goal being to understand the reasons for eels adopting a certain life history strategy (FW or SW residency vs. ‘habitat shifting’), we explored differences in lipid content and FA composition of muscle, liver and eyes from eels collected across Norwegian SW, BW and FW habitats, and at different lifecycle stages (yellow to silver). FW and SW eels had a higher lipid content overall compared to BW eels, reflecting differences in food availability and life history strategies. SW eels had higher proportions of certain monounsaturated FAs (MUFAs; 18:1n-9, 20:1n-9), and of the essential polyunsaturated FAs 20:5n-3 (eicosapentaenoic acid, EPA) and 22:6n-3 (docosahexaenoic acid) than FW eels, reflecting a marine-based diet. In contrast, the muscle of FW eels had higher proportions of 18:3n-3, 18:2n-6 and 20:4n-6 (arachidonic acid), as is typical of FW organisms. MUFA proportions increased in later stage eels, consistent with the hypothesis that the eels accumulate energy stores prior to migration. In addition, the decrease of EPA with advancing stage may be associated with the critical role that this FA plays in eel sexual development. Lipid and FA information provided further understanding of the habitat use and overall ecology of this critically endangered species. 相似文献
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Imre Taal Martin Kesler Lauri Saks Mehis Rohtla Aare Verliin Roland Svirgsden Kristiina Jürgens Markus Vetemaa Toomas Saat 《Helgoland Marine Research》2014,68(2):373-377
In the eastern Baltic rivers, anadromous salmonid parr are known to smoltify and migrate to the sea from March until June, depending on latitude, climate and hydrological conditions. In this study, we present the first records of autumn descent of brown trout Salmo trutta and Atlantic salmon Salmo salar from the Baltic Sea Basin. Otolith microchemistry analyses revealed that these individuals hatched in freshwater and had migrated to the brackish water shortly prior to capture. The fish were collected in 2006, 2008, 2009 and 2013 from Eru Bay (surface salinity 4.5–6.5 ‰), Gulf of Finland. This relatively wide temporal range of observations indicates that the autumn descent of anadromous salmonids is not a random event. These results imply that autumn descent needs more consideration in the context of the effective stock management, assessment and restoration of Baltic salmonid populations and their habitats. 相似文献
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Evidence of Atlantic salmon Salmo salar fry movement between fresh water and a brackish environment 下载免费PDF全文
I. Taal M. Rohtla L. Saks R. Svirgsden M. Kesler L. Matetski M. Vetemaa 《Journal of fish biology》2017,91(2):695-703
This study reports descent of Atlantic salmon Salmo salar fry from their natal streams to brackish waters of the Baltic Sea and their use of this environment as an alternative rearing habitat before ascending back to freshwater streams. To the authors' knowledge, residency in a brackish environment has not previously been demonstrated in S. salar fry. Recruitment success and evolutionary significance of this alternative life‐history strategy are presently not known. 相似文献
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Mehis Rohtla Lagle Matetski Imre Taal Roland Svirgsden Martin Kesler Päärn Paiste Markus Vetemaa 《Journal of fish biology》2020,97(5):1582-1585
For the first time, an overlooked aspect of partial migration was quantified using otolith microchemistry and brown trout, Salmo trutta, as a model species. Relative contributions of freshwater resident and anadromous female brown trout to mixed-stock sea trout populations in the Baltic Sea were estimated. Out of 236 confirmed wild sea trout sampled around the coast of Estonia 88% were of anadromous maternal origin and 12% were of resident maternal origin. This novel finding underscores the importance of the resident contingent in maintaining the persistence and resilience of the migratory contingent. 相似文献
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Jonne Kotta Katarina Oganjan Velda Lauringson Merli P?rnoja Ants Kaasik Liisa Rohtla Ilmar Kotta Helen Orav-Kotta 《PloS one》2015,10(8)
Benthic suspension feeding mussels are an important functional guild in coastal and estuarine ecosystems. To date we lack information on how various environmental gradients and biotic interactions separately and interactively shape the distribution patterns of mussels in non-tidal environments. Opposing to tidal environments, mussels inhabit solely subtidal zone in non-tidal waterbodies and, thereby, driving factors for mussel populations are expected to differ from the tidal areas. In the present study, we used the boosted regression tree modelling (BRT), an ensemble method for statistical techniques and machine learning, in order to explain the distribution and biomass of the suspension feeding mussel Mytilus trossulus in the non-tidal Baltic Sea. BRT models suggested that (1) distribution patterns of M. trossulus are largely driven by separate effects of direct environmental gradients and partly by interactive effects of resource gradients with direct environmental gradients. (2) Within its suitable habitat range, however, resource gradients had an important role in shaping the biomass distribution of M. trossulus. (3) Contrary to tidal areas, mussels were not competitively superior over macrophytes with patterns indicating either facilitative interactions between mussels and macrophytes or co-variance due to common stressor. To conclude, direct environmental gradients seem to define the distribution pattern of M. trossulus, and within the favourable distribution range, resource gradients in interaction with direct environmental gradients are expected to set the biomass level of mussels. 相似文献
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This study investigated the movement patterns of Baltic Sea pike Esox lucius in Matsalu Bay, Estonia, using otolith microchemistry. Migration patterns of E. lucius were remarkably diverse, but distinct groups were evident. Of the E. lucius analysed (n = 28), 82% hatched in fresh water and 74% of them left this biotope during the first growth season. 相似文献
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Atko Viru Livian Laaneots Kalle Karelson Tamara Smirnova Mehis Viru 《European journal of applied physiology and occupational physiology》1998,77(5):401-408
The dependence of exercise-induced hormone responses on sexual maturation was tested in a 3-year longitudinal experiment
on 34 girls (aged 11–12 years at the beginning). Sexual maturation was evaluated by Tanners five-stage scale. Children cycled
for 20-min at 60% maximal oxygen uptake once a year. Cortisol, insulin, growth hormone, β-oestradiol, progesterone and testosterone
concentrations in venous blood were determined by radioimmunoassay procedures. Basal concentrations of growth hormone increased
and of cortisol decreased when breast stage III was reached. Reaching breast stage IV was associated with an increase in basal
concentrations of β-oestradiol, progesterone and testosterone. The exercise induced significant increases in concentrations
of cortisol, growth hormone and β-oestradiol and a decrease in insulin concentration. At breast stage III the increase in
cortisol concentration was to a lower level [467 (SEM 42) vs 567 (SEM 46)nmol · l−1] and growth hormone concentration to a higher level [29.4 (SEM 0.5) vs 12.8 (SEM 0.4)ng · ml−1], while the fall in insulin concentration was less pronounced [postexercise level 10.6 (SEM 0.9) vs 7.8 (SEM 0.8)mU · l−1] than in stage II. The magnitude of the cortisol response was reduced in the last stage of breast development (+42.1% vs
+55.5% at stage II, +66.2% at stage III, and +50.0% at stage IV). The magnitude of β-oestradiol response was the lowest in
breast stage IV (+15.8%) and the highest at stage V (+41.1%). The progesterone response became significant at stage IV and
testosterone response at stage V. In conclusion, we found that reaching breast stage III was associated with altered responses
of cortisol, insulin and growth hormone concentrations while the responses of the sex hormone concentrations became pronounced
in the last stages of sexual maturation.
Accepted: 17 September 1997 相似文献