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1.
  1. The Amazon Basin is being degraded at unprecedented rates, yet conservation efforts have implemented protected areas to curb deforestation, leaving freshwater ecosystems vulnerable to degradation. Amazon freshwater ecosystems are largely unprotected because a terrestrial bias has limited the ability of science to affect policy.
  2. Overcoming this bias requires increasing exchange of information among stakeholders across the basin to raise awareness of threats to Amazon freshwater ecosystems and promote discussions and access to conservation solutions. To help address this need, this Special Issue collates 15 synthetic articles that advance knowledge and identify conservation solutions.
  3. Three articles highlight the importance of considering the hydrological and limnological processes that control the integrity of these freshwater ecosystems and offer new insights on how to extrapolate them across the basin.
  4. Three articles on crocodilians, aquatic mammals, and migratory fishes document threats and knowledge gaps, and identify the missing role of governments as an impediment to conservation of their populations.
  5. Three articles evaluate the multi-faceted effects of hydropower dams on fish, birds, and floodplain trees. They reinforce perceptions that dams are key environmental threats and offer guidance for improving protocols for dam site selection and impact assessment.
  6. Three articles assessing the effectiveness of protected areas to safeguard fish and aquatic invertebrates show there is an urgent need to redesign the Amazon protected area network to adequately protect freshwater biota.
  7. Three forward-looking articles show that: (i) conservation initiatives by local communities are ‘bright spots’ for freshwater conservation; (ii) microchemistry analyses of the ear bones of fishes could boost the knowledge base needed to conserve them; and (iii) strengthening the Amazon conservation framework requires a reversal of Brazil's current governmental priorities, remobilization of stakeholders, investments in capacity building, and expanding protections to terrestrial and freshwater ecosystems.
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2.
  1. In the context of the River Rhône restoration programme, the objective of this study was to assess the dispersal and population connectivity of the European chub, Squalius cephalus (Linnaeus, 1758) in a section of the natural, free-flowing part of the lower River Rhône.
  2. The elemental water signatures for Sr:Ca and Ba:Ca were measured at seven stations within the river section, including its tributaries and backwaters, to determine whether they could be differentiated by microchemistry. From August to October the signatures differed among three sectors of the study reach: the Rhône; the Ardèche; and the backwaters.
  3. The elemental signatures of the otoliths of 178 young-of-the-year (YOY) chub from the stations were measured to assess spawning areas and identify early migratory life histories. Analyses of otolith microchemistry identified the natal origin of 95% of the fish. Sr:Ca signatures of otoliths showed early downstream migration for 30.4% of the YOY chub; however, 70% of the fish recruited relatively close to their spawning origin suggesting a potential inshore retention of fish.
  4. The results showed (i) a non-negligible contribution of the tributaries and backwaters in the recruitment of fish into the main channel; and (ii) the ability of chub to migrate over several kilometres during their first few months of life.
  5. This study shows that the combination of water and otolith microchemistry analyses of fish growth increases the understanding of fish life history. Moreover, the study revealed that half of the YOY fish from this river section came from the tributaries and the other half came from reproduction in the River Rhône (despite its high anthropization).
  6. These methods offer promising future applications of otolith microchemistry for river management in the context of ecological rehabilitation, especially to assess the effectiveness of measures applied in the restoration of floodplain connectivity for riverine fish population conservation.
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3.
  1. Frugivorous fish provide often conflicting ecosystem services of seed dispersal and food provisioning in tropical rivers. Fishing may reduce the size and abundance of frugivorous fish, thus affecting their potential as seed dispersers, which could affect the conservation of these fish and of floodplain forests.
  2. The goal of this study was to assess the influence of co-managed protected areas in the form of extractive reserves (RESEX) and small-scale fisheries on frugivorous fish in the Tapajós and Negro rivers, in the Brazilian Amazon. The study examined whether: (i) frugivorous fish are important for fisheries and selectively caught; and (ii) frugivorous fish abundance, size and fisheries catch per unit of effort are higher inside the RESEX than outside.
  3. The analyses included fisheries-dependent data (3,753 fish landings) and independent data (12,730 sampled fish) collected in 16 fishing communities (eight for each river). In both rivers, frugivorous fish are among the 10 species caught the most and frugivorous biomass was proportionately higher in landings than in samplings, indicating fisheries selectivity towards these fishes.
  4. In both rivers, catches of frugivorous fish were higher outside the RESEX than inside. Catch per unit effort and the proportion of frugivores in the catch were higher outside the RESEX in the Tapajós River but did not vary between sites inside and outside the RESEX in the Negro River. Frugivorous fish were larger inside the RESEX in the Negro, but smaller inside the RESEX in the Tapajós.
  5. The results indicated that the ecosystem services of seed dispersal and food source provided by frugivorous fish are not in conflict in the tropical rivers studied. Therefore, these clearwater and blackwater rivers in the Brazilian Amazon show a balance between fisheries and conservation of frugivorous fish, which play an essential role in the functioning of tropical floodplain forest ecosystems.
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4.
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5.
  1. The Amazon basin hosts the Earth's highest diversity of freshwater fish. Fish species have adapted to the basin's size and seasonal dynamics by displaying a broad range of migratory behaviour, but they are under increasing threats; however, no study to date has assessed threats and conservation of Amazonian migratory fishes.
  2. Here, the available knowledge on the diversity of migratory behaviour in Amazonian fishes is synthesized, including the geographical scales at which they occur, their drivers and timing, and life stage at which they are performed.
  3. Migratory fishes are integral components of Amazonian society. They contribute about 93% (range 77–99%) of the fisheries landings in the basin, amounting to ~US$436 million annually.
  4. These valuable fish populations are mainly threatened by growing trends of overexploitation, deforestation, climate change, and hydroelectric dam development. Most Amazonian migratory fish have key ecological roles as apex predators, ecological engineers, or seed-dispersal species. Reducing their population sizes could induce cascading effects with implications for ecosystem stability and associated services.
  5. Conserving Amazonian migratory fishes requires a broad portfolio of research, management, and conservation actions, within an ecosystem-based management framework at the basin scale. This would require trans-frontier coordination and recognition of the crucial importance of freshwater ecosystems and their connectivity.
  6. Existing areas where fishing is allowed could be coupled with a chain of freshwater protected areas. Management of commercial and subsistence species also needs fisheries activities to be monitored in the Amazonian cities and in the floodplain communities to allow assessments of the status of target species, and the identification of management units or stocks. Ensuring that existing and future fisheries management rules are effective implies the voluntary participation of fishers, which can be achieved by increasing the effectiveness and coverage of adaptive community-based management schemes.
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6.
  1. Limnological aspects of Amazon floodplain lakes are examined in the context of aquatic conservation.
  2. A prerequisite to detecting and evaluating changes that could threaten the ecological health and organisms in floodplain lakes is understanding variation under present conditions. Based on one of the few studies with regular measurements over 2 years, chlorophyll, total phosphorus, dissolved oxygen, transparency, and total suspended solids in Lake Janauacá indicate that the lake is naturally quite variable with a mesotrophic to eutrophic status.
  3. Direct threats to ecological health of floodplain lakes include mining operations that can increase turbidity and trace metals and reduce nutritional quality of sediments. Mercury contamination and methylation leads to bioaccumulation in aquatic organisms.
  4. Deforestation in uplands increases nitrogen and phosphorus inputs to floodplain lakes and can alter trophic status. Deforestation in floodable forests alters the habitat and food of the fish that inhabit these forests.
  5. Cumulative limnological responses as catchments are altered by urban, agricultural, and industrial developments, and as inundation is altered by changes in climate and construction of dams, have major implications for the ecology of floodplain lakes.
  6. To improve understanding and management of threats to the conservation of aquatic Amazon biota and ecosystems requires considerably expanded and coordinated research and community-based management that includes the spectrum of floodplain lakes throughout the basin.
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7.
  1. Free-flowing tributaries are important for the maintenance of fish diversity in dammed systems. In relation to the reproduction of fish species, the role of a free-flowing tributary was evaluated and compared with that of a dammed tributary downstream of large dams in the Madeira River, one of the main tributaries of the Amazon River.
  2. Two hypotheses were tested: (i) the densities of the ichthyoplankton differ between the dammed and the free-flowing tributaries; and (ii) the free-flowing tributary contributes a greater diversity of fish larvae species to the assemblage structure of the main stem than the dammed tributary.
  3. Fish eggs and larvae were sampled at five sites: one in each tributary (Jamari – dammed – and Machado – free-flowing) and three in the main stem (Madeira River), upstream and downstream from the mouth of each tributary.
  4. Fitted Bayesian models showed that the densities both of eggs and larvae were more than twice as high in the free-flowing tributary than in the dammed tributary. The results also indicated that the free-flowing tributary makes a major contribution to the fish assemblage structure of the Madeira River, whereas the dammed tributary does not have a significant influence on the main stem assemblage structure.
  5. The results demonstrate the importance of conservation and maintenance not only of the Machado River but also of other free-flowing tributaries in dammed basins, especially those basins with high biodiversity, such as the Amazon. Moreover, this study helps inform the decision-making process regarding the location of new dams, which is critical in fish diversity conservation.
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8.
  1. Aquatic mammals worldwide are highly threatened in freshwater ecosystems where they are affected by direct human activities (e.g. hunting) as well as indirect human alteration of freshwater ecosystems (e.g. dams, mining activity). Although aquatic mammals of the Amazon Basin are experiencing many growing threats, little is known about the escalating impacts on them, current limitations in protection mechanisms, and possible strategies to ensure their conservation. This study synthesizes the available information on Amazonian aquatic mammals, including the ecological characteristics of these species, key threats, population status and conservation prospects.
  2. Amazonian aquatic mammals comprise seven species – Inia geoffrensis, Inia boliviensis, Inia araguaiaensis, Sotalia fluviatilis, Trichechus inunguis, Pteronura brasiliensis and Lontra longicaudis – which are characterized by low reproductive rates and keystone ecosystem roles. These species are endangered mainly by biological resource use, natural ecosystem modifications, energy production and mining, and climate change. Although information is sparse, there is evidence that these threats are inducing population declines of Inia spp., and hindering the recovery of populations of P. brasiliensis.
  3. Protection mechanisms for these species mostly include national and international laws and agreements, legislation governing environmental licensing and protected areas. Each of these protection mechanisms, however, has limited capacity to protect Amazonian aquatic mammals, largely because they are poorly enforced, lack transnational coordination or require population trend data that do not exist.
  4. Reversing the current state of affairs for Amazonian aquatic mammals requires an integrated research and policy approach that, at a minimum, substantially increases the present capacity to monitor their population responses to human impacts, establishes effective enforcement of existing legislation and prevents further impacts from hydropower development. To implement such an approach, information on the ecology of these species is necessary to create public and scientific awareness.
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9.
  1. Climate change is causing shifts in the distribution patterns of freshwater fish at various spatio-temporal scales. Tropical freshwater fish are vulnerable, especially in areas where a high impact of climate change is predicted; thus, there is an increasing need to predict these shifts to determine conservation and adaptation strategies.
  2. Ecological niche models offer a reliable way to predict the effects of climate change on species distribution. Potential shifts in the distribution of tropical fish were tested under two scenarios (4.5 – moderate and 8.5 – extreme) with three general circulation models for years 2050 and 2070 using maximum entropy software using as models two predatory species – the tropical gar Atractosteus tropicus and the giant cichlid Petenia splendida.
  3. The potential distribution of both species was associated with warm and humid–sub-humid conditions. Future projections showed a higher availability of suitable areas for both species resulting from the expansion of warmer conditions in the middle and upper basins of the Central American mountain range and centre of the Yucatan Peninsula.
  4. Ecological niche models of keystone or umbrella species such as A. tropicus and P. splendida could be useful to support conservation plans of protected areas. The potential distribution of both species covers areas of high suitability including six important biosphere reserves in Mexico, three protected areas in Guatemala and part of the Mesoamerican biological corridor.
  5. Despite the potential expansion of the present distribution range suggested by the models, it is important to consider the biological and ecological requirements of the species and the ecological implications of these potential shifts in distribution. Both scenarios could have several implications at genetic, population, and ecosystem levels.
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10.
  1. Freshwater ecosystems represent less than 0.01% of Earth's surface water but proportionately encompass the most species-rich environment on the planet, including nearly one-third of all vertebrate species. Even though inland continental waters are widely regarded as highly endangered ecosystems, their species assemblages are mostly ignored in conservation plans, largely because spatial patterns of freshwater species remain poorly understood. This is particularly severe throughout the Neotropics, most notably in the Amazon superbasin, where the sheer biotic diversity is coupled with a severe lack of biodiversity knowledge at several levels.
  2. Spatial patterns of Neotropical freshwater fishes focusing mainly on the Amazon superbasin were investigated. First, Endemic Amazonian Fish Areas (EAFAs) representing central units for the conservation of continental fishes were delimited. Interpolated maps were then analysed using alternative methodologies to delimit spatial patterns of diversity and endemicity across the Amazon superbasin. Several biogeographical analyses used a comprehensive dataset of species and geographical coordinates of Amazonian fishes.
  3. The results reveal well-defined spatial patterns of species richness and endemicity in the Amazonian fish fauna, showing that most protected areas are concentrated in a single bioregion (Amazon lowlands). Those areas are incongruent and insufficient to protect endemic and threatened species, which are mostly distributed in upland regions.
  4. Effective conservation of the Amazonian fish fauna should include EAFAs within protected areas, especially those undergoing deforestation and hydropower development pressure and containing a high concentration of threatened species.
  5. The following EAFAs should be considered as conservation priorities: Upper Araguaia, Upper Tocantins, Lower Teles Pires/Serra do Cachimbo, Chapada dos Parecis and Upper Marañon. These regions should be urgently protected to avert the loss of important trophic relationships and unique elements of the Amazonian fish fauna.
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11.
  1. Freshwater ecosystems, providing valuable goods and services to humans, have been subjected to multiple human impacts, among which climate change plays a central role in threats to species. It is expected that protected areas, the cornerstone of biodiversity conservation efforts, will assume a decisive role in protecting freshwater species from the impacts of climate change.
  2. This study assessed the effects of climate change on migratory fish of the second largest neotropical river basin, evaluating the effectiveness of protected areas in safeguarding fish species, and hence the ecological functions that they perform and the ecosystem resources that they provide. The present range of 23 migratory fish of economic interest in the Paraná–Paraguay basin was estimated and the responses to future climatic shifts projected to the middle and end of the 21st century were examined, quantifying predictive uncertainties.
  3. Changes and losses of climatically suitable areas will trigger severe contractions in range, with the greatest impact on the most valuable species in commercial fishing, where range losses are likely to surpass 65% in the future. The main channel of the Upper Paraná River and tributaries of its left margin are projected to serve as climatic refuges for many species, and such regions are not affected by high predictive uncertainty. The results revealed that protected areas do not sufficiently protect migratory fish at present, and that they will continue to offer negligible protection in the face of climate change.
  4. This study alerts decision makers to the potential damage to inland fishery resources from climate change and provides useful information to guide conservation strategies spatially. We advocate that the creation of new protected areas and the redesign of the existing network to encompass regions that maximize current and future occupancy of migratory fish are crucial to conserve the valuable ecological, societal, and economic benefits that they provide.
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12.
  • 1. Marine protected areas (MPAs) are set up to conserve biodiversity, but their design is not always based on strictly scientific considerations. Ideally, an MPA should protect all key habitats necessary for a marine species to complete its life cycle. The identification of these key habitats is complex, especially during the early life of marine fishes.
  • 2. A widely distributed tropical and important low trophic‐level fish species, Spratelloides delicatulus (Clupeidae), was used to evaluate the significance of various coastal habitats for its larvae and juveniles in the Con Dao Archipelago MPA in Vietnam. Early stages (larvae and juveniles) were sampled monthly over one year (June 2016 to May 2017) using light traps in three main habitats (seagrass beds, coral reefs and harbour). The species was identified using morphometry and DNA barcoding. Age and growth variables were estimated using otolith daily growth increments.
  • 3. A total of 3,581 fish were caught. The species was not found in captures between January and February, directly linked to the decrease in seawater temperature and was most abundant from April to June. For a subsample of 248 fish (7–38 mm standard length), ages ranged from 7 to 108 days.
  • 4. Captures and back‐calculated birthdates using otolith daily increments showed that S. delicatulus spawns during the period of high seawater temperature, from March to October. The species colonizes all three habitats during the early stages (0–26 days old), with growth rate lowest on the seagrass beds. Nevertheless, the species occupies seagrass beds exclusively during the older stages.
  • 5. The conservation of seagrass beds in the Con Dao archipelago is essential for protection of juvenile stages of this species but this habitat is presently not included in the MPA patches. Establishment of a continuum of protected areas linking habitats, rather than the existing patches is needed to conserve the complete life cycle of this species in the Con Dao MPA.
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13.
  1. Governance of natural resources in the Amazon has changed over time, especially when it comes to participatory regimes. Yet these regimes have rarely focused on the conservation of aquatic systems or have failed to fully deliver social justice.
  2. Participatory regimes in the Amazon basin that rely on the provision of freshwater ecosystem services can potentially favour transformative and just conservation. A framework referred to as the ‘Just Aquatic Governance’ model is proposed to organize and facilitate the transition of continuing and future endeavours that seek conservation while also supporting distinct aspects of social justice.
  3. If conservation of aquatic systems can be reconciled with all aspects of social justice, then transformative and just governance regimes could emerge without further burdening those at the forefront of conservation.
  4. The Just Aquatic Governance framework is divided into three aspects of social justice, organized according to the following pillars: (i) recognitional – support for cultural diversity and the maintenance of livelihoods, including food security; (ii) procedural – the right to autonomy and territory, and support for participatory forms of governance; and (iii) distributional – promotion of gender equality and fair distribution of economic benefits.
  5. Although not a panacea, the model proposed here, which can also influence policy strategies, can potentially align both conservation demands and social aspirations in the Amazon – a historical, yet still imperative, need in the region.
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14.
  1. To understand the ecological factors behind the decline of functionally important threatened species with complex life cycles, many different life‐cycle stages need to be investigated. The highly threatened unionoid freshwater mussels, with their complex life cycle, including a parasitic stage on host fish, often have a large influence on biodiversity and ecosystem functioning.
  2. The overall aim of the present article is to summarize and discuss the impact of two articles published in Aquatic Conservation: Marine and Freshwater Ecosystems (AQC) on biotic interactions and adaptation of a threatened unionoid mussel (Margaritifera margaritifera) to its host fish (Salmo trutta).
  3. The two AQC publications described research on the influence of population size and density of mussels and host fish, and host–parasite interactions between mussels and their host fish, on the recruitment of juvenile mussels.
  4. The results from these publications filled gaps in knowledge and resulted in recommendations and incentives for conservation. The results and method development have been used in practical conservation work with threatened mussel species and have been implemented and cited in management handbooks. The outcome of the publications has been implemented in large conservation and restoration projects, and in several recent scientific publications.
  5. Specifically, the results from one publication showed that ecological parameters such as mussel and host fish density and population size influenced recruitment of the threatened freshwater pearl mussel. The results from the second publication showed that understanding host–parasite interactions is important for comparing the suitability of host fish strains, and that host fish strains differ in their suitability for mussel infestations. In combination, the articles show that integrating ecological parameters of threatened mussels and their host fish with host–parasite interaction experiments can be an important influence on conservation recommendations, adaptive management and national management programmes for threatened species.
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15.
  1. Conservation of riverine fish often aims to improve access to spawning grounds and restore longitudinal connectivity by removing migration barriers, and involves substantial investments. However, these investments also enable non‐native predators to invade upstream into spawning areas and potentially adversely affect the recruitment of threatened freshwater fish through egg or fry predation.
  2. Detecting egg predation is often challenging. Visual inspections of fish gut contents may underestimate predation of soft materials such as eggs and fry, which limits the discovery of predators preying upon these life‐stages. DNA‐based detection assays may offer a more sensitive tool to assess predation of soft materials.
  3. A conservation issue was confirmed by developing and applying a species‐specific DNA‐based detection assay: invasive round goby (Neogobius melanostomus) prey on the eggs or fry of the threatened common nase (Chondrostoma nasus) in Switzerland.
  4. DNA‐based detection assays were also developed for five other valuable native fish species, including endangered salmonid and cyprinid river spawners. The applicability of the assays was confirmed in a series of laboratory and field feeding experiments involving eggs and fish tissue. In addition, this work provides a guiding framework for conservation managers regarding the use and applicability of different DNA‐based detection approaches for gut content analysis.
  5. The results of this study could inform local conservation measures – such as temporary reductions in the density of round goby at spawning sites prior to spawning – and demonstrate how targeted application of species‐specific molecular markers may advance freshwater fish management.
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16.
  1. The Amazon basin has been subjected to extreme climatic events and according to climate change projections this hydrosystem could face changes in the natural dynamic of flood cycles that support the feeding and reproduction of many fish species, threatening aquatic biodiversity.
  2. Protected areas (PAs) are the main tools used to safeguard the biodiversity in the long term; however, they are fixed areas that could be subject to climate change, questioning their future efficiency in protecting biodiversity.
  3. The Amazon basin currently benefits from a relatively high level of protection as 52% of its catchment area is under the form of true PAs or indigenous lands. However, the capacity of these PAs to protect freshwater biodiversity remains unclear as they have generally been assessed with little regard to freshwater ecosystems and their hydrological connectivity. Here, the aim was to evaluate the effectiveness of PAs in representing the Amazon fish fauna under current and future climatic conditions.
  4. A macroecological approach was used to estimate the minimum size of the geographical range needed by each species to achieve long-term persistence, by a combined function of range size and body size, two ecological traits known to influence species extinction risk.
  5. In future the Amazon basin could risk losing 2% of its freshwater fish fauna owing to unsuitable climatic conditions, with a further 34% adversely affected. The present Amazon network of PAs will cover the minimum required range for species persistence for more than 60% of the freshwater fish species analysed under the future climate scenario. However, more than 25% of the future susceptible species are currently concentrated in large tributaries and in the central-lower Amazon floodplain where few PAs occur, highlighting the lack of appropriate conservation actions for these specific water bodies.
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17.
  1. Juvenile Pacific salmon exhibit diverse habitat use and migration strategies to navigate high environmental variability and predation risk during freshwater residency. Increasingly, urbanization and climate-driven hydrological alterations are affecting the availability and quality of aquatic habitats in salmon catchments. Thus, conservation of freshwater habitat integrity has emerged as an important challenge in supporting salmon life-history diversity as a buffer against continuing ecosystem changes.
  2. To inform catchment management for salmon, information on the distribution and movement dynamics of juvenile fish throughout the annual seasonal cycle is needed. A number of studies have assessed the ecology of juvenile coho salmon (Oncorhynchus kisutch) during summer and autumn seasons; catchment use by this species throughout the annual cycle is less well characterized, particularly in high-latitude systems.
  3. Here, n = 3,792 tagged juvenile coho salmon were tracked throughout two complete annual cycles to assess basin-wide distribution and movement behaviour of this species in a subarctic, ice-bearing catchment.
  4. Juvenile coho salmon in the Big Lake basin, Alaska, exhibited multiple habitat use and movement strategies across seasons; however, summer rearing in lotic mainstem environments followed by migration to lentic overwinter habitats was identified as a prominent behaviour, with two-thirds of tracked fish migrating en masse to concentrate in a small subset of upper catchment lakes for the winter. In contrast, the most significant tributary overwintering site (8% of tracked fish) occurred below a culvert and dam, blocking juvenile fish passage to a headwater lake, indicating that these fish may have been restricted from reaching preferred lentic overwinter habitats.
  5. These findings emphasize the importance of maintaining aquatic connectivity to lentic habitats as a conservation priority for coho salmon during freshwater residency.
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18.
  1. Tetraodontiformes fishes play a critical role in benthic and demersal communities and are facing threats due to anthropogenic impacts and climate change. However, they are poorly studied worldwide. To improve knowledge on the socio‐ecological significance and conservation of Tetraodontiformes a review of literature addressing the diversity, ecology, use and trade, conservation, and main threats of Tetraodontiformes combined with a comprehensive in situ dataset from two broad‐range multidisciplinary oceanographic surveys performed along the Tropical Brazilian Continental Shelf was undertaken.
  2. Twenty‐nine species were identified, being primarily found on coral reefs and algal ecosystems. At these habitats, tetraodontids present highly diversified trophic categories and might play an important role by balancing the marine food web
  3. Coral reef ecosystems, especially those near to the shelf break, seem to be the most important areas of Tetraodontiformes fishes, concentrating the highest values of species richness, relative abundance and the uncommon and Near Threatened species.
  4. Ninety per cent of species are commonly caught as bycatch, being also used in the ornamental trade (69%) and as food (52%), serving as an important source of income for artisanal local fisheries.
  5. Tetraodontiformes are threatened by unregulated fisheries, overexploitation, bycatch, and habitat loss due to coral reef degradation and the potential effects of climate change. These factors are more broadly impacting global biodiversity, food security, and other related ecosystem functions upon which humans and many other organisms rely.
  6. We recommend the following steps that could improve the conservation of Tetraodontiformes along the tropical Brazilian Continental shelf and elsewhere: (i) data collection of the commercial, incidental, ornamental and recreational catches; (ii) improvement of the current legislation directed at the marine ornamental harvesting; (iii) increase efforts focused on the education and conservation awareness in coastal tourism and communities; and, most important, (iv) creation of marine reserves networks in priority areas of conservation, protecting either the species and key habitats for its survival.
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19.
  1. The extent and intensity of impacts of multiple new dams in the Amazon basin on specific biological groups are potentially large, but still uncertain and need to be better understood.
  2. It is known that river disruption and regulation by dams may affect sediment supplies, river channel migration, floodplain dynamics, and, as a major adverse consequence, are likely to decrease or even suppress ecological connectivity among populations of aquatic organisms and organisms dependent upon seasonally flooded environments.
  3. This article complements our previous results by assessing the relationships between dams, our Dam Environmental Vulnerability Index (DEVI), and the biotic environments threatened by the effects of dams. Because of the cartographic representation of DEVI, it is a useful tool to compare the potential hydrophysical impacts of proposed dams in the Amazon basin with the spatial distribution of biological diversity. As the impact of Amazonian dams on the biota of both rivers and periodically flooded riparian environments is severe, DEVIs from different Amazonian tributary basins are contrasted with patterns of diversity and distribution of fish, flooded forest trees and bird species.
  4. There is a consistent relationship between higher DEVI values and the patterns of higher species richness and endemism in all three biological groups. An assessment of vulnerability at the scale of tributary basins, the assessment of biodiversity patterns related to DEVI, and the analysis of teleconnections at basin scale, demonstrate that recent construction of dams is affecting the biota of the Amazon basin.
  5. The evidence presented here predicts that, if currently planned dams are built without considering the balance between energy production and environmental conservation, their cumulative effects will increase drastically and represent a major threat to Amazonian biodiversity.
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20.
  1. River fish diversity is threatened by anthropogenic environmental alteration to landscapes. The early life-history stages of fish play an important role in maintaining diversity and population recruitment and can be heavily influenced by landscape patterns. Information on temporal and spatial distribution patterns of fish eggs and larvae is also important for biodiversity conservation and management of fish resources.
  2. The Yangtze River possesses a high diversity of fishes, including many commercially important species. The economy along the lower reach of the river is well developed, and most of the area is experiencing high pressure from human impacts. This section of the Yangtze River connects with the largest freshwater lake in China at the upstream end and flows into the estuary at the downstream end. These two landscape features are likely to have a significant impact upon the spatial distributions of fish egg and larval assemblages.
  3. Environmental variables, fish eggs, and larval assemblages were sampled in three locations, at Hukou, Anqing, and Jingjiang, in the lower reach of the Yangtze River. The results suggest that the higher number of species and greater abundance in upstream sites reflect the critical function of connectivity of Poyang Lake with the river for fish recruitment in the lower Yangtze. The delayed bloom of larval fish, occurrence of estuarine species, and a lower species number and abundance of freshwater fish downstream reflect the influence of tidal intrusion from the estuary.
  4. This study highlights the value of maintaining natural river–lakes connectivity in the Yangtze River as a conservation measure. The connected river–lake system should be designated as a priority area for fish resource protection in the lower reach of the Yangtze River. We recommend further measures to break down barriers between the river and other lakes and to restore the natural lateral connectivity of the floodplain ecosystem.
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