Commercial traceability of <i>Arapaima</i> spp. fisheries in the Amazon basin: can biogeochemical tags be useful?

The development of analytical tools to determine the origin of fishes is useful to better understand patterns of habitat use and to monitor, manage, and control fisheries, including certification of food origin. The application of isotopic analyses to study calcified structures of fishes (scales, vertebrae, and otoliths) may provide robust information about the fish geographic origin and environmental living conditions. In this study, we used Sr and C isotopic markers recorded in otoliths of wild and farmed commercialized pirarucu (Arapaima spp.) to evaluate their prediction potential to trace the fishes origin. Wild and farmed fish specimens, as well as food used for feeding pirarucu in captivity, were collected from different sites. Isotope composition of otoliths performed by isotope-ratio mass spectrometry (IRMS; δ13C) and femtosecond laser ablation multi-collector inductively coupled plasma mass spectrometry (LAfs-MC-ICPMS; 87Sr∕86Sr) were compared to the isotopic composition of water and of the food given to the fishes in the farms. Wild fish specimens that lived in environments with the largest fluctuation of river water Sr isotope ratios over time presented the largest Sr isotope variations in otoliths. A quadratic discriminant analysis on otolith isotopic composition provided 58&thinsp;% of correct classification for fish production (wild and farmed) and 76&thinsp;% of correct classification for the fish region. Classification accuracy for region varied between 100&thinsp;% and 29&thinsp;% for the Madeira and the Lower Amazon fishes, respectively. Overall, this preliminary trial is not yet fully developed to be applied as a commercial traceability tool. However, given the importance of Arapaima spp. for food security and the generation of economic resources for millions of people in the Amazon basin, further analyses are needed to increase the discrimination performance of these biogeographical tags.</p

Commercial traceability of <i>Arapaima</i> spp. fisheries in the Amazon basin: can biogeochemical tags be useful?

The development of analytical tools to determine the origin of fishes is useful to better understand patterns of habitat use and to monitor, manage, and control fisheries, including certification of food origin. The application of isotopic analyses to study calcified structures of fishes (scales, vertebrae, and otoliths) may provide robust information about the fish geographic origin and environmental living conditions. In this study, we used Sr and C isotopic markers recorded in otoliths of wild and farmed commercialized pirarucu (Arapaima spp.) to evaluate their prediction potential to trace the fishes origin. Wild and farmed fish specimens, as well as food used for feeding pirarucu in captivity, were collected from different sites. Isotope composition of otoliths performed by isotope-ratio mass spectrometry (IRMS; δ13C) and femtosecond laser ablation multi-collector inductively coupled plasma mass spectrometry (LAfs-MC-ICPMS; 87Sr∕86Sr) were compared to the isotopic composition of water and of the food given to the fishes in the farms. Wild fish specimens that lived in environments with the largest fluctuation of river water Sr isotope ratios over time presented the largest Sr isotope variations in otoliths. A quadratic discriminant analysis on otolith isotopic composition provided 58&thinsp;% of correct classification for fish production (wild and farmed) and 76&thinsp;% of correct classification for the fish region. Classification accuracy for region varied between 100&thinsp;% and 29&thinsp;% for the Madeira and the Lower Amazon fishes, respectively. Overall, this preliminary trial is not yet fully developed to be applied as a commercial traceability tool. However, given the importance of Arapaima spp. for food security and the generation of economic resources for millions of people in the Amazon basin, further analyses are needed to increase the discrimination performance of these biogeographical tags.</p

6. Peces amazónicos y cambio climático

Con el 15% de todos los peces de agua dulce descritos en el mundo, la cuenca amazónica es el sistema de agua dulce más biodiverso del planeta. Hoy en día, los factores principales de degradación de los ecosistemas de agua dulce en la región amazónica son la rápida expansión de las infraestructuras y actividades económicas. Estas perturbaciones provocan importantes efectos negativos en las comunidades de peces y podrían verse amplificados por los impactos del cambio climático. Las pérdidas de hábitat originados por el cambio climático no deberían tener efectos sobre las tasas de extinción de la especies. Sin embargo, el estrés térmico y la limitación de oxígeno podrían provocar extinciones locales de ciertas especies y producir cambios progresivos en la estructura y composición de las comunidades actuales de peces. Las especies tolerantes al aumento de temperatura, como el Paiche, se expandirán mientras que las especies sensibles a este aumento se reducirán. Cabe destacar que hoy en día las acciones de conservación deben enfocarse en la reducción de los efectos de las amenazas antropogénicas en curso.Avec 15% de tous les poissons d'eau douce décrits dans le monde, le bassin amazonien est le système d'eau douce présentant la plus grande biodiversité de la planète. Aujourd'hui, les principaux facteurs de dégradation des écosystèmes d'eau douce dans la région amazonienne sont l'expansion rapide des infrastructures et les activités économiques. Ces perturbations provoquent d'importants effets négatifs sur les communautés de poissons et pourraient être amplifiés par les impacts du changement climatique. La perte d'habitat due au changement climatique ne devrait avoir aucun effet sur les taux d'extinction des espèces. Cependant, le stress lié à la température et la limitation de l'oxygène pourraient provoquer l'extinction locale de certaines espèces et produire des changements progressifs dans la structure et la composition des communautés actuelles de poissons. Les populations d'espèces tolérantes à l'augmentation de température, comme le Paiche, augmenteront, tandis que les populations d'espèces sensibles à cette augmentation diminueront. Il est important de noter que, à l'heure actuelle, les actions de conservation doivent se concentrer sur la réduction des effets des menaces anthropiques en cours.With 15% of all described freshwater fish in the world, the Amazon basin is the most biodiverse freshwater System of the planet. Nowadays, the main factors of degradation of freshwater ecosystems in the Amazon region are the rapid expansion of infrastructure and economic activities. These disturbances cause negative effects on fish communities and could be amplified by the impacts of climate change. Loss of habitat due to climate change should have no effect on rates of species extinction. However, thermal stress and oxygen limitation could cause local extinctions of certain species and produce Progressive changes in the structure and composition of existing fish communities. Tolerant species to temperature increase -as the Paiche- should expand, while sensitive species should be reduced. It is noteworthy that conservation actions should focus on reducing the effects of anthropogenic threats in progress

Dealing with Food and Eggs in Mouthbrooding Cichlids: Structural and Functional Trade-Offs in Fitness Related Traits

As in any vertebrate, heads of fishes are densely packed with functions. These functions often impose conflicting mechanical demands resulting in trade-offs in the species-specific phenotype. When phenotypical traits are linked to gender-specific parental behavior, we expect sexual differences in these trade-offs. This study aims to use mouthbrooding cichlids as an example to test hypotheses on evolutionary trade-offs between intricately linked traits that affect different aspects of fitness. We focused on the oral apparatus, which is not only equipped with features used to feed and breathe, but is also used for the incubation of eggs. We used this approach to study mouthbrooding as part of an integrated functional system with diverging performance requirements and to explore gender-specific selective environments within a species.Because cichlids are morphologically very diverse, we hypothesize that the implications of the added constraint of mouthbrooding will primarily depend on the dominant mode of feeding of the studied species. To test this, we compared the trade-off for two maternal mouthbrooding cichlid species: a "suction feeder" (Haplochromis piceatus) and a "biter" (H. fischeri). The comparison of morphology and performance of both species revealed clear interspecific and intersex differences. Our observation that females have larger heads was interpreted as a possible consequence of the fact that in both the studied species mouthbrooding is done by females only. As hypothesized, the observed sexual dimorphism in head shape is inferred as being suboptimal for some aspects of the feeding performance in each of the studied species. Our comparison also demonstrated that the suction feeding species had smaller egg clutches and more elongated eggs.Our findings support the hypothesis that there is a trade-off between mouthbrooding and feeding performance in the two studied haplochromine cichlids, stressing the importance of including species-specific information at the gender level when addressing interspecific functional/morphological differences

Competitive Interactions between Invasive Nile Tilapia and Native Fish: The Potential for Altered Trophic Exchange and Modification of Food Webs

Recent studies have highlighted both the positive and negative impacts of species invasions. Most of these studies have been conducted on either immobile invasive plants or sessile fauna found at the base of food webs. Fewer studies have examined the impacts of vagile invasive consumers on native competitors. This is an issue of some importance given the controlling influence that consumers have on lower order plants and animals. Here, we present results of laboratory experiments designed to assess the impacts of unintended aquaculture releases of the Nile tilapia (Oreochromis niloticus), in estuaries of the Gulf of Mexico, on the functionally similar redspotted sunfish (Lepomis miniatus). Laboratory choice tests showed that tilapia prefer the same structured habitat that native sunfish prefer. In subsequent interspecific competition experiments, agonistic tilapia displaced sunfish from their preferred structured habitats. When a piscivore (largemouth bass) was present in the tank with both species, the survival of sunfish decreased. Based on these findings, if left unchecked, we predict that the proliferation of tilapia (and perhaps other aggressive aquaculture fishes) will have important detrimental effects on the structure of native food webs in shallow, structured coastal habitats. While it is likely that the impacts of higher trophic level invasive competitors will vary among species, these results show that consequences of unintended releases of invasive higher order consumers can be important

Parallel Evolution of a Type IV Secretion System in Radiating Lineages of the Host-Restricted Bacterial Pathogen Bartonella

Adaptive radiation is the rapid origination of multiple species from a single ancestor as the result of concurrent adaptation to disparate environments. This fundamental evolutionary process is considered to be responsible for the genesis of a great portion of the diversity of life. Bacteria have evolved enormous biological diversity by exploiting an exceptional range of environments, yet diversification of bacteria via adaptive radiation has been documented in a few cases only and the underlying molecular mechanisms are largely unknown. Here we show a compelling example of adaptive radiation in pathogenic bacteria and reveal their genetic basis. Our evolutionary genomic analyses of the α-proteobacterial genus Bartonella uncover two parallel adaptive radiations within these host-restricted mammalian pathogens. We identify a horizontally-acquired protein secretion system, which has evolved to target specific bacterial effector proteins into host cells as the evolutionary key innovation triggering these parallel adaptive radiations. We show that the functional versatility and adaptive potential of the VirB type IV secretion system (T4SS), and thereby translocated Bartonella effector proteins (Beps), evolved in parallel in the two lineages prior to their radiations. Independent chromosomal fixation of the virB operon and consecutive rounds of lineage-specific bep gene duplications followed by their functional diversification characterize these parallel evolutionary trajectories. Whereas most Beps maintained their ancestral domain constitution, strikingly, a novel type of effector protein emerged convergently in both lineages. This resulted in similar arrays of host cell-targeted effector proteins in the two lineages of Bartonella as the basis of their independent radiation. The parallel molecular evolution of the VirB/Bep system displays a striking example of a key innovation involved in independent adaptive processes and the emergence of bacterial pathogens. Furthermore, our study highlights the remarkable evolvability of T4SSs and their effector proteins, explaining their broad application in bacterial interactions with the environment