Selective pressure of fishways upon morphological and muscle enzymatic traits of migrating glass eels

2017 ◽  
Vol 74 (4) ◽  
pp. 445-451 ◽  
Author(s):  
T. Podgorniak ◽  
M. Angelini ◽  
E. De Oliveira ◽  
F. Daverat ◽  
F. Pierron
Keyword(s):  
Energy Metabolism ◽  
Selective Pressure ◽  
Condition Factor ◽  
Anguilla Anguilla ◽  
Aquatic Habitats ◽  
Size Selectivity ◽  
Glass Eel ◽  
Glass Eels ◽  
Species Specific

Fishways are built on obstacles to restore the connectivity between aquatic habitats. Our study investigated how species-specific fishways interact with interindividual trait differences among fish. We compared several groups of glass eels (Anguilla anguilla) climbing two types of fishways with those remaining below the water impoundments. We analyzed relative body condition factor, body length, mass, and in vitro activities and gene transcription levels of several enzymes involved in the energy metabolism (LDH, CS, CCO, PK). Differences among groups indicated that glass eel fish ladders can be size-specific, according to the type of substrate covering the surface of apparatus. Moreover, we found that climbing specific glass eel ladders can require higher endurance-related metabolic traits, triggering increased aerobic capacities. Increased aerobic efforts together with potential size selectivity of fishways should be taken into account when designing such devices and choosing appropriate location on eel migratory pathways.

Challenges to quantifying glass eel abundance from large and dynamic estuaries

2017 ◽  
Vol 75 (2) ◽  
pp. 727-737 ◽  
Author(s):  
Sarah Walmsley ◽  
Julie Bremner ◽  
Alan Walker ◽  
Jon Barry ◽  
David Maxwell
Keyword(s):  
Large Scale ◽  
Anguilla Anguilla ◽  
Commercial Fishing ◽  
European Eel ◽  
Estuarine System ◽  
Glass Eel ◽  
The North ◽  
Adequate Sampling ◽  
South Shore ◽  
Glass Eels

Abstract European eel Anguilla anguilla recruitment into the rivers of the northeastern Atlantic has declined substantially since the 1980s. Monitoring of recruiting juveniles, or glass eels, is usually undertaken in small estuaries and rivers. Sampling of large-scale estuaries is rare, due to the size of the sampling area and the resources needed to provide adequate sampling levels. Here we describe surveys for glass eels in the UK’s largest estuarine system, the Severn Estuary/Bristol Channel. We sampled across a 20 km-wide stretch of the estuary in 2012 and 2013, using a small-meshed net deployed from a commercial fishing trawler, and the surveys yielded over 2500 glass eels. Eels were more abundant in the surface layer (0–1.4 m depth) than at depth (down to 8.4 m depth), were more abundant close to the south shore than along the north shore or middle of the estuary, and were more abundant in lower salinity water. Numbers were higher in the second year than in the first and eels were more abundant in February than April. The difficulties and logistics of sampling in such a large estuary are discussed, along with the level of resources required to provide robust estimates of glass eel abundance.

scholarly journals Age, growth, and condition of European eel (Anguilla anguilla) from six lakes in the River Havel system (Germany)

2007 ◽  
Vol 64 (7) ◽  
pp. 1414-1422 ◽  
Author(s):  
Janek Simon
Keyword(s):  
Growth Rate ◽  
Condition Factor ◽  
Energy Content ◽  
Anguilla Anguilla ◽  
European Eel ◽  
Annual Increment ◽  
Otolith Increments ◽  
Gross Energy ◽  
Glass Eels ◽  
Mean Annual Increment

Abstract Simon, J. 2007. Age, growth, and condition of European eel (Anguilla anguilla) from six lakes in the River Havel system (Germany). – ICES Journal of Marine Science, 64: 1414–1422. A total of 199 female yellow European eels (Anguilla anguilla), 21.6–66.2 cm long and 3–14 years old, was collected by electro-fishing from six lakes in the River Havel system (Germany) in spring 2001. The condition and the growth rate, estimated by otolith increments, varied between eels within single lakes and between lakes. Fulton's condition factor ranged from 0.10 to 0.24 and the gross energy content varied between 4.3 and 15.3 MJ kg−1. There were no significant differences in mean condition factor (0.16–0.18) or gross energy content (6.5–9.3 MJ kg−1) between lakes. Fastest growth was in Lake Blankensee (mean 5.3 cm year−1), and the slowest in Lake Sacrow (mean 4.0 cm year−1). For all lakes combined, the overall mean annual increment was estimated to be 4.5 cm year−1. The biggest annual increment on the otoliths was generally laid down during the first and second years in fresh water, when the growth rate was 6.1–8.5 cm year−1. Then, in the subsequent 12 years, the annual increment remained almost constant or decreased slightly (with lake-dependent values of between 1.6 and 6.8 cm year−1). In the River Havel system, the time between stocking of the lakes with glass eels and the recapture of eels at 45 cm body length was 7–10 years. The physiologically possible maximum length (L∞ values) of eels lay in the range 50–130 cm. In comparison with previous investigations (between the 1950s and the 1970s), the only difference observed was a trend towards slower growth.

Osmoregulatory plasticity of the glass eel of Anguilla anguilla: freshwater entry and changes in branchial ion-transport protein expression

2004 ◽  
Vol 61 (3) ◽  
pp. 432-442 ◽  
Author(s):  
Jonathan Mark Wilson ◽  
José Carlos Antunes ◽  
Patricío Duro Bouça ◽  
João Coimbra
Keyword(s):  
Ion Transport ◽  
River Estuary ◽  
Anguilla Anguilla ◽  
Chloride Cells ◽  
Concentration Gradients ◽  
Glass Eel ◽  
Ru 486 ◽  
Minho River ◽  
History Of ◽  
Glass Eels

The glass-eel stage of the life history of Anguillid eels (Anguilla spp.) makes the important physiological transition from seawater (SW) to freshwater (FW) osmoregulation. Central to successful adaptation to fresh water is the switch from active hypoosmoregulation (ion excretion) to active hyperosmoregulation (ion uptake) to counter passive fluxes imposed by concentration gradients. Anguilla anguilla (L.) glass eels, captured from the lower Minho River estuary and maintained in brackish water (BW; 24‰), were fully capable of adapting to FW following acute transfer. In a comparison between SW- (34‰) and FW-adapted glass eels, gill Na+/K+-ATPase and Na+:K+:2Cl– cotransporter (NKCC) expression were both markedly reduced in the FW group. Branchial mitochondria-rich chloride cells (MRCs) were also significantly larger in SW-adapted glass eels. Apical CFTR Cl– channel immunoreactivity associated with branchial MRCs was also only present in SW-adapted glass eels. The expression of these three ion-transport proteins is strongly associated with active ion excretion in SW teleost fishes. In FW-adapted glass eels, cortisol treatment increased branchial Na+/K+-ATPase expression but was without effect on NKCC expression. Glucocorticoid receptor blockade by RU-486 had no effect on Na+/K+-ATPase or NKCC expression.

scholarly journals Experimental field study on the migratory behaviour of glass eels (Anguilla anguilla) at the interface of fresh and salt water

2007 ◽  
Vol 64 (7) ◽  
pp. 1396-1401 ◽  
Author(s):  
Tammo P. Bult ◽  
Willem Dekker
Keyword(s):  
Field Study ◽  
Salt Water ◽  
Anguilla Anguilla ◽  
Migratory Behaviour ◽  
Glass Eel ◽  
Experimental Field ◽  
Tidal Stream ◽  
Glass Eels ◽  
Selective Tidal Stream Transport ◽  
Stream Transport

Abstract Bult, T. P., and Dekker, W. 2007. Experimental field study on the migratory behaviour of glass eels (Anguilla anguilla) at the interface of fresh and salt water. – ICES Journal of Marine Science, 64: 1396–1401. European eels (Anguilla anguilla) in the glass eel phase migrate using ocean currents and selective tidal stream transport. Conventional fish ladders installed at the interface of marine and fresh water, however, require the fish to swim upstream actively. We question the efficiency of these fish ladders for glass eel immigration, and propose a simple siphon over migration barriers, restoring the original selective tidal stream transport. A conventional trap and our siphon were tested concurrently at two sluice complexes in The Netherlands (Tholen, Nieuwe Statenzijl) in spring 2005. In all but one case, the siphon caught more glass eels than the trap, as well as more sticklebacks and other species. Clearly, the natural immigration process can be restored fairly easily and at low cost and with low intrusion levels of salt. Follow-up studies should focus on optimization, and the effect of a passage on the hinterland stock.

Novel Toxin-antitoxin System Xn-mazEF from Xenorhabdus nematophi-la: Identification, Characterization and Functional Exploration

2020 ◽  
Vol 16 ◽  
Author(s):  
Jogendra Singh Nim ◽  
Mohit Yadav ◽  
Lalit Kumar Gautam ◽  
Chaitali Ghosh ◽  
Shakti Sahi ◽  
...  
Keyword(s):  
Interaction Analysis ◽  
Functional Characterization ◽  
Host Cells ◽  
System Control ◽  
Xenorhabdus Nematophila ◽  
Functional Features ◽  
Dynamics Simulations ◽  
Species Specific ◽  
Rna Interaction

Background: Xenorhabdus nematophila maintains species-specific mutual interaction with nematodes of Steinernema genus. Type II Toxin Antitoxin (TA) systems, the mazEF TA system controls stress and programmed cell death in bacteria. Objective: This study elucidates the functional characterization of Xn-mazEF, a mazEF homolog in X. nematophila by computational and in vitro approaches. Methods: 3 D- structural models for Xn-MazE toxin and Xn-MazF antitoxin were generated, validated and characterized for protein - RNA interaction analysis. Further biological and cellular functions of Xn-MazF toxin were also predicted. Molecular dynamics simulations of 50ns for Xn-MazF toxin complexed with nucleic acid units (DU, RU, RC, and RU) were performed. The MazF toxin and complete MazEF operon were endogenously expressed and monitored for the killing of Escherichia coli host cells under arabinose induced tightly regulated system. Results: Upon induction, E. coli expressing toxin showed rapid killing within four hours and attained up to 65% growth inhibition, while the expression of the entire operon did not show significant killing. The observation suggests that the Xn-mazEF TA system control transcriptional regulation in X. nematophila and helps to manage stress or cause toxicity leading to programmed death of cells. Conclusion: The study provides insights into structural and functional features of novel toxin, XnMazF and provides an initial inference on control of X. nematophila growth regulated by TA systems.

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