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Catherine Taverny Isabelle Ortusi Charles Roqueplo Mario Lepage Patrick Lambert 《Ecology of Freshwater Fish》2012,21(1):87-99
Abstract – Habitat requirements of lamprey ammocoetes (Petromyzon marinus and Lampetra genus) were investigated, for the first time, from shallow to deep waters, at different spatial scales across the Gironde‐Dordogne continuum, thanks to a water suction dredge. Fish‐habitat relationships were assessed through two complementary statistical analyses: habitat‐use curves and habitat suitability models using the Boosted Regression Trees (BRT) technique. Analyses were performed on a small‐size data set that was characterised by the low prevalence of lamprey. The sea lamprey larvae occurred in deeper areas than their Lampetra genus counterparts. ‘Pools’ of 2 m’ depth and more were optimal habitats for the former species. Among the environmental variables retained to model lamprey occurrences, the mesohabitat (a categorical variable) was demonstrated to be highly influential, in terms of fine grain‐size substratum and vegetation cover. These preliminary results suggest that monitoring using the water suction dredge method may contribute to sea lamprey conservation. 相似文献
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- 1. River lamprey (Lampetra fluviatilis) and sea lamprey (Petromyzon marinus) are designated features of the River Derwent Special Area of Conservation (SAC) and the Humber Estuary (a possible SAC). This study determined the condition of lamprey populations in the Yorkshire Ouse catchment by assessing the species composition, distribution, abundance and size‐structure of larval (ammocoete) populations in five major tributary rivers (Derwent, Swale, Ure, Nidd and Wharfe).
- 2. According to EU condition assessment criteria, Lampetra populations (assumed to be mostly river lamprey) are at present in favourable condition, with site mean (±SE) densities ranging from 2.7 (±1.2) to 160.3 (±50.5) individuals m?2 (all river means >2 individuals m?2), and at least two size (≈age) classes present in optimal microhabitats. By contrast, no sea lamprey larvae were recorded, suggesting that populations of this species are in unfavourable condition.
- 3. Actions to protect and enhance nationally or internationally important stocks must be implemented from at least a catchment perspective, because many of the issues affecting such species are not localized. With respect to lampreys, particular attention should be given to protecting spawning and nursery habitats, improving water quality, reducing impingement at abstraction points, preventing exploitation at spawning grounds and increasing passage at potential physical obstructions.
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More information on the habitat requirements of lamprey is needed to improve measures aiming at rehabilitation of lamprey populations. Knowledge on habitat requirements of subyearling lampreys is especially scarce. We studied substrate selection by subyearling lamprey during the first three months after hatching using aquarium experiments. Differences in substrate selection by different‐sized larvae older than one year and the substrate depth selection by large larvae were also studied. Prolarvae of an average total length (TL) of 6.9 mm actively selected substrates with existing holes. When lampreys reached TL of over 8.0 mm, they started to select substrates which enabled them to construct a burrow. Lampreys of that size avoided coarse sand and gravel without fine material. Natural gravel with fine material was a frequently selected burrowing substrate during the 10‐week experiment suggesting its importance for subyearling lampreys. Substrates where very fine sand prevailed were the most selected soft sediments by subyearling larvae. Larvae older than one year did not select clay as a burrowing substrate. Medium (TL 70–98 mm) and large (TL 110–146 mm) larvae preferred coarse organic matter to fine sand. Larvae older than one year (TL 80–110 mm) preferred the thickest layer of soft substrate (10 cm) available to thinner layers. 相似文献
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R. Galloway I. C. Potter D. J. Macey R. W. Hilliard 《Fish physiology and biochemistry》1987,4(2):63-72
The standard rate of oxygen consumption of ammocoetes (larvae) ofGeotria australis with a mean weight of c. 0.5 g was 9.6, 31.4 and 59.4l g–1 h–1 at 4.5, 15.5 and 25.0°C respectively, which gives an overall Q10 of 2.4. The regression coefficient for the logarithmic relationship between oxygen consumption and body weight at 15.5°C was 0.704. The ammocoetes ofG. australis have a much lower rate of oxygen consumption at 15.5 and 25.0°C than those of holarctic lampreys. This presumably reflects the lower oxygen delivery pressure to their tissues and helps account for their slow growth rate. At 15.5°C, ammocoetes ofG. australis emerged from the substrate at 21–25 mm Hg and, unlike those of the Northern HemisphereIchthyomyzon greeleyi, died at 14–17 mm Hg. Thus, despite having a thinner water/blood barrier in the gills and blood with a higher oxygen affinity and capacity than holarctic ammocoetes, the larvae ofG. australis cannot survive very low dissolved oxygen tensions. This is apparently related to an inability of larvalG. australis to meet the high oxygen requirements of the respiratory pump at these oxygen tensions. During metamorphosis, oxygen consumption at 15.5°C rose from approximately 27l g–1 h–1 at the beginning of transformation to 33.2l g–1 h–1 by Stage 3 and then rapidly to 66l g–1 h–1 at Stage 6. It remained near this level in Stage 7 and the downstream migrant. 相似文献
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