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Cuif, M., Keller, F., Chateau, O., Kaplan, D., Labonne, M., Lett, C., et al. (2014). Evaluation of transgenerational isotope labeling of embryonic otoliths in a coral reef damselfish with single and repeated injections of enriched (137)Barium. Journal of Experimental Marine Biology and Ecology, 459, 151–159.
Résumé: Quantifying the larval dispersal component of population connectivity is extremely challenging due to the many difficulties associated with directly observing larvae in their marine environment. Transgenerational isotope labeling is a recent empirical technique that addresses this challenge. It relies on the transmission of an artificially enriched stable isotope (e.g., Ba-137) from gravid females to the embryonic otoliths of their offspring, allowing for mass permanent marking of larvae. Before implementing transgenerational isotope labeling in the wild, it is essential to investigate the transmission longevity of the mark from females to larvae and to assess the potential negative effects on females and their offspring. We injected females of the Humbug damselfish, Dascyllus aruanus, with an enriched Ba-137 solution and reared the resulting progeny to test the marking success and the transmission longevity of the mark, as well as determine potential effects of transgenerational isotope labeling on spawning frequency and size of 1-day eggs and 2-day larvae. Three different single-injection dosages (0.5, 1 and 5 mu g of Ba-137 g(-1) fish weight) were tested, as well as monthly repeated injections of the lowest dosage over a whole reproductive season. We implemented a new method that allows extracting otoliths of newly hatched larvae and analyzing them using laser ablation coupled plasma mass spectrometry (ICP-MS). We showed that for D. aruanus, injection with a low dose (0.5 mu g Ba-137 g(-1), fish weight) produced consistently significantly marked larvae with a half-life for successful enriched Ba mark transmission of approximately 1 month, and that monthly repeated injections of this dose did not negatively impact spawning success or condition of eggs and larvae. Monthly repeated injections of enriched Ba isotope injections at 0.5 mu g Ba-137 g(-1) fish weight will therefore present an effective means of mass marking D. aruanus larvae throughout an entire reproductive season.
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Hampton, S. L., Moloney, C. L., van der Lingen, C. D., & Labonne, M. (2018). Spatial and temporal variability in otolith elemental signatures of juvenile sardine off South Africa. J. Mar. Syst., 188, 109–116.
Résumé: Otolith elemental signatures can be used to identify when individual or groups of fish are spending a significant amount of time in different environments. Elemental signatures of juvenile sardine Sardinops sagax caught in winter 2008 and 2009 around the coast of South Africa were measured using inductively-coupled plasma mass-spectroscopy. The otolith elemental signatures of 34 fish caught in 2008 and of 52 fish caught in 2009 were measured at the edge (to represent conditions 20-30 days prior to capture). Principal component analysis was used to visualise the relationships of individuals to each other, in terms of their otolith chemistry, in two-dimensional space, and multiple ANOVAs were used to investigate spatial and temporal variations among samples collected in 2008 and 2009. Significant differences among sites were found in MANOVAs, but the between-site differences varied among the elements. Magnesium concentration tended to decrease whereas barium concentration tended to increase from the west to the east coast. Barium indicate upwelling impact but for 2008 samples on the northern part of the west coast. Otolith microchemistry provides evidence of large and small-scale differentiation in sardine, but differences between years indicates that this is not necessarily temporally stable. The ocean off South Africa is a dynamic and variable environment and this is reflected in the inter-site, and also inter-annual, differences in elemental signatures of juvenile sardine.
Mots-Clés: anchovy; challenges; chemistry; fingerprints; fish; Microchemistry; Otoliths; protein; salinity; Sardine; Stock structure; stocks; temperature; Upwelling; water
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Hauser, M., Duponchelle, F., Hermann, T. W., Limburg, K. E., Castello, L., Stewart, D. J., et al. (2020). Unmasking continental natal homing in goliath catfish from the upper Amazon. Freshw. Biol., 65(2), 325–336.
Résumé: Amazonian goliath catfishes are widespread in the Amazon Basin. Recently, otolith Sr-87:Sr-86 analyses using laser ablation-multi-collector-inductively coupled plasma mass spectrometry (LA-MC-ICPMS) revealed a >8,000 km trans-Amazonian natal homing in Brachyplatystoma rousseauxii among fish caught and hatched in the largest Amazon River tributary, the upper Madeira basin. Although also suspected for fish in the upper Amazon, homing could not be demonstrated owing to less distinct environmental Sr-87:Sr-86 gradients along the Amazon mainstem. Using scanning X-ray fluorescence microscopy (SXFM), a separate study provided evidence that Se:Ca and Sr:Ca are useful markers for identifying migration into Andean headwaters and the estuarine environment. We analysed otoliths of known Sr-87:Sr-86 profiles using SXFM mapping to test if Sr:Ca and Se:Ca patterns could demonstrate natal homing for three fish caught in the upper Amazon, using as reference two individuals that were natal homers and two forced residents (hatched after the construction of hydroelectric dams on the Madeira River) from the upper Madeira River. As hypothesised, although the Sr isotope profiles of the upper Amazon individuals were uninformative, two of them presented similar alternating mirror patterns of Sr:Ca and Se:Ca to those of the upper Madeira natal homers, indicating migrations out of the Andean region and into the estuary area. Both were therefore natal homers from the upper Amazon. The third individual from the upper Amazon presented similar Sr:Ca and Se:Ca patterns to those of the upper Madeira residents, suggesting it was a natural resident from the upper Amazon. By combining the results of Sr-87:Sr-86 analyses (LA-MC-ICPMS) and Sr:Ca and Se:Ca mappings (SXFM) that are completely independent of one another, we demonstrated that B. rousseauxii also performs natal homing in the upper Amazon. Our results indicate that the life cycle of B. rousseauxii is more complex than previous literature hypothesised, with the existence of partial migration, even in absence of physical barriers. Quantifying the relative importance of these different life-history strategies will have important implications for fisheries management. Our results also lay the groundwork for conservation efforts in the context of hydropower development in the Amazon Basin and set testable hypotheses of the potential impacts of the Madeira River dams.
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Morat, F., Letourneur, Y., Blamart, D., Pecheyran, C., Darnaude, A. M., & Harmelin-Vivien, M. (2014). Offshore-onshore linkages in the larval life history of sole in the Gulf of Lions (NW-Mediterranean). Estuarine Coastal and Shelf Science, 149, 194–202.
Résumé: Understanding individual dispersion from offshore natal areas to coastal nurseries during pelagic larval life is especially important for the sustainable management of exploited marine fish species. For several years, the hatching period, the larval life duration, the average growth rate and the otolith chemical composition (delta C-13, delta O-18, Sr:Ca and Ba:Ca) during the larval life were studied for young of the year (YOY) of sole collected in three main nurseries of the Gulf of Lions (GoL) (Thau, Mauguio and Berre). We investigated the spatial variation in the origin of the sole larvae which colonised the nurseries around the GoL, and whether temporal differences in environmental conditions during this life stage affected growth and larval life duration. The hatching period ranges from October to March, depending on year and site. Average ages at metamorphosis varied between 43 and 50 days, with the lowest and highest values consistently found for Mauguio and Berre, respectively. Otolith growth rates ranged between 2.7 and 3.2 mu m d(-1), with the lowest values in Thau and Mauguio and the highest in Berre. Otolith chemical composition during the larval life also varied, suggesting contrasted larval environmental histories in YOY among nurseries. In fishes from Berre and Mauguio, larval life was more influenced by the Rhone River, showing consistently higher larval Ba:Ca ratios (10/23 mu mol mol(-1)) and lower delta C-13 (-6.5/-6.1 parts per thousand) and delta O-18 values (-1.6/0.1 parts per thousand) than for Thau (with Ba:Ca ratios < 8 mu mol mol(-1), delta C-13 similar to-2.3 parts per thousand and delta O-18 similar to 1.5 parts per thousand). Differences in larval otolith composition were observed for 2004, with higher Ba:Ca and lower delta C-13 and delta O-18 values than in the two other years. These differences were explained by changes in composition and chemical signatures of water masses after an exceptional flooding event of the Rhone River in late 2003. (C) 2014 Elsevier Ltd. All rights reserved.
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Panfili, J., Darnaude, A. M., Lin, Y. J., Chevalley, M., Iizuka, Y., Tzeng, W. N., et al. (2012). Habitat residence during continental life of the European eel Anguilla anguilla investigated using linear discriminant analysis applied to otolith Sr:Ca ratios. Aquat. Biol., 15(2), 175–185.
Résumé: European eel Anguilla anguilla migratory behaviour during continental life is still unclear due to the multiplicity of aquatic environments colonised by the species. In the Camargue area (NW Mediterranean), eel colonisation of the Fumemorte canal, a freshwater habitat that communicates only with a vast brackish ecosystem (the Vaccares lagoon), offers a rare opportunity to test for freshwater habitat residence during continental life. To this end, both laser ablation inductively coupled plasma mass spectrometry and electron probe micro-analysis were used to measure chronological variations of strontium concentrations (Sr:Ca) in the otoliths of 58 silver eels captured in the canal between 1997 and 2007. Comparing mean Sr: Ca ratios measured on otolith edges with the 2 analytical methods indicated that they provide comparable measurement accuracies. Linear discriminant analysis (LDA), based on the otolith Sr: Ca values corresponding to the initial entrance of the fish into the brackish ecosystem and their final capture in the freshwater canal, allowed successful discrimination of the 2 habitats and reconstruction of migratory history for all individuals. Six different migratory behaviours were identified. Eels that entered the freshwater canal did so either directly (67%) or after 1 to 2 yr spent in the lagoon (33%), with a subsequent majority of freshwater residents (55%) until their silvering. These results indicate the value of LDA for reconstructing habitat use during continental life using Sr: Ca ratios. They confirm the occurrence of freshwater residence during continental life in European eels, even in Mediterranean continental areas where brackish environments are predominant. This observed sedentary behaviour has implications for eel population management and conservation.
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