Historical abundance and distributions of Salpa thompsoni hot spots in the Southern Ocean and projections for further ocean warming

1. In contrast to Antarctic krill Euphausia superba, Antarctic salps (Salpa thompsoni) respond positively to warmer water temperatures and have the ability to create massive blooms under favourable conditions. Therefore, they can compete with krill for primary production. Over the last three decades, significant variability in S. thompsoni occurrence has been observed as a response to the environmental fluctuations of the Southern Ocean ecosystem (e.g. changes in sea surface temperature and ice-cover shrinkage around the cold Antarctic waters).
2. This study presents historical abundance data of salps from the south-west Atlantic Sector of the Southern Ocean, covering a time span of 26 years. These data allow tracking of fluctuations in Antarctic salp abundance and their distribution with bottom depth, temperature, and ice conditions, aiming to reveal salp hot spots and to predict the future range of S. thompsoni distribution with upcoming climate warming in the next 50 years.
3. Results showed the highest salp density in shallow shelf waters with ice cover and low temperatures between 1 and −1°C. In the studied area, S. thompsoni hot spots were located mostly around Elephant Island, but also the islands around Brensfield and Gerlache Straits, as well as to the south near the Bellingshausen Sea. Inferences made of future salp distribution suggest that the range of S. thompsoni will move southwards, enlarging their habitat area by nearly 500,000 km², which may have significant implications on the whole Antarctic food web. The information presented herein may be used for Antarctic ecosystem management, protection, and conservation.

     

Foraging areas of black‐browed and grey‐headed albatrosses breeding on Macquarie Island in relation to marine protected areas

• 1. Although marine protected areas (MPAs) are often established to protect threatened top‐order predators, there is a paucity of data that can be used to evaluate their efficacy in achieving this purpose.
• 2. We assessed the effectiveness of a network of MPAs around Macquarie Island in the Southern Ocean by examining the foraging areas of breeding black‐browed Thalassarche melanophrys and grey‐headed albatrosses T. chrysostoma.
• 3. During late incubation and brood periods over 90% of time spent foraging by black‐browed albatrosses was contained within MPAs, principally the Economic Exclusion Zone (EEZ) around Macquarie Island. In contrast, grey‐headed albatrosses spent only 34% of their time foraging in MPAs.
• 4. Black‐browed and grey‐headed albatrosses spent 30% and 15% of their respective foraging times in the Marine Park around Macquarie Island.
• 5. Both black‐browed and grey‐headed albatrosses foraged in Antarctic waters under the jurisdiction of the Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR), accounting for 5% and 12% of the total foraging times respectively.
• 6. The spatial extent of MPAs around Macquarie Island appear to adequately cover much of the foraging distribution of breeding black‐browed albatrosses from Macquarie Island.
• 7. Breeding grey‐headed albatrosses spend significantly more time in waters outside the spatial extent of the surrounding MPAs and are at higher risk from fisheries activities and other threats.
• 8. Further information on the foraging movements both of albatrosses outside the breeding season and of juvenile albatrosses is required to more fully assess the efficacy of MPAs in protecting foraging habitats of these species.

Copyright © 2005 John Wiley & Sons, Ltd.     

Mountains‐to‐the‐sea conservation: An island perspective

1. Island nations such as New Zealand provide valuable insights into conservation challenges posed by strongly connected and recently developed or exploited freshwater and marine ecosystems.
2. The narrow land mass, high rainfall, and steep terrain of New Zealand, like many other island nations, mean that land‐based stressors are rapidly transferred to freshwater habitats and propagated downstream to coastal environments via short, fast‐flowing river systems.
3. Freshwater and marine environments are linked through faunal life histories; for example, diadromous fishes, many of which are considered threatened or at risk of extinction, and require cross‐ecosystem conservation to ensure survival of critical life stages and persistence of source populations.
4. Recent invasions of marine and freshwater environments by non‐indigenous species reveal rapid impacts on a naïve biota and highlight conservation conundrums caused by management aimed at enhancing native biodiversity by improving habitat connectivity.
5. Understanding and managing interconnected freshwater and marine ecosystems is a key concept for local indigenous communities, and highlights socio‐cultural connectivity and sustainable local harvesting of traditional resources as key elements of contemporary marine and freshwater conservation planning in New Zealand.

     

Long‐term changes of marine subtidal benthic communities in North East Asia (Yellow and Japan seas) in a global change context: A review

1. A review of the long‐term changes and variations in benthic communities and the current status of the marine invasive species (MIS) in shallow waters of the Yellow Sea (Chinese sector) and the Sea of Japan (Russian and partly Korean sectors) is presented. This paper reflects on the progress and lessons learned, recommending actions for the future about the conservation of biodiversity.
2. In the Bohai Sea, the benthic ecosystem has been degenerating due to anthropogenic activities such as overfishing and pollution since the 1950s. The dominant position of K‐strategy species is gradually being lost and replaced by R‐strategy species. In the Yellow Sea, the macrobenthic community is different from other areas due to the Yellow Sea Cold Water Mass. Many economic species have been destroyed, and the biotic structure has changed significantly due to overfishing and climate change.
3. In the Russian sector of the Sea of Japan, the macrobenthic communities in the shallow‐water soft bottom have generally been in a stable condition for the last decades, except for some heavily polluted or disturbed areas due to dredging operations. The abundance of select large invertebrate species has changed considerably due to commercial fishing and poaching. Variations in macro? and meiobenthic communities under aquaculture conditions have occurred on a local scale during the last five decades.
4. MIS show obvious differences between China and Russia in the following aspects: introduction pathways of MIS, composition and number of non‐native species, threats and impacts of MIS to native communities and ecosystems, and economic and public health impacts.
5. Long‐term monitoring programmes should be developed to reveal future biotic changes and to separate the effects of cyclic variations of benthic communities from the impacts of pollution and eutrophication. Standardization of sampling procedures is required to compare changes/alternations in benthos across various regions worldwide.

     

Towards local governance of marine resources and ecosystems on Easter Island

1. Social‐ecological system sustainability depends in part upon the fit between ecosystems and institutions.
2. In 2014, the local community on Easter Island started a bottom‐up process to improve marine resources conservation and management.
3. Local stakeholders formed a working group that has regular meetings and goals, such as creating a sea council and some basic action plans, thus initiating a local governance transformation process.
4. A participatory process was conducted together with a local organization that led the marine conservation issues on the island to define the factors that could favour and/or undermine the formation of the sea council. Also, the stakeholders that must be present in such a sea council were identified.
5. Twelve factors that could facilitate or hinder the implementation of a sea council were identified. The lack of representativeness of public institutions is a major challenge.
6. Public institutions are designed to ensure compliance with central government strategies, but the decisions do not represent the worldview of islanders.
7. The results showed the potential value of conducting a participatory process to identify the key issues that could hinder or favour a desired governance transformation process. The participatory process also highlighted governance mismatches that are important to consider in attempts to pursue more effective fishery governance on Easter Island, and other Island communities.
8. Centralized governance systems do not respond rapidly to locally observed social and ecological dynamics. By contrast, a local decision‐making system based on traditional laws and local governance can more rapidly respond to observed changes.
9. The participatory process presented here holds the potential to support local people in their planning and coordination for marine conservation and management in order to optimize bottom‐up change processes involving multiple stakeholders with different interests, values and levels of power.

Copyright © 2016 John Wiley & Sons, Ltd.     

Beyond one bone: Interdisciplinarity to assess nativeness of the tench (Tinca tinca) in Spain

1. The native or non‐native status of a species can be difficult to discern when it has been present in a territory for a long time. To solve these conflicting cases it is often important to integrate the knowledge from multiple disciplines, because narrow‐focused approaches can produce misleading perceptions around nativeness.
2. The tench (Tinca tinca) is thought to be native in Spain, and officially considered so, only because of putative Bronze Age remains of the species from a single archaeological site.
3. This putative prehistoric record is here revisited and put into context using evidence from other approaches and disciplines, to show that the native status of the tench in Spain is solely based on an arguably erroneous identification of the remains of a single bone.
4. Biogeographical and genetic patterns solidly support the non‐native status of the tench, and historical documents contain explicit records of the importation of the species to Spain in the sixteenth century. The tench must thus be considered a non‐native species in Spain and managed as such.
5. This review shows how weak observations and errors can be entrenched in the scientific literature as established truths through repeated uncritical citations, with pervasive effects both for knowledge building and for the management of natural resources.

     

Irresponsible vendors: Non‐native,invasive and threatened animals offered for garden pond stocking

1. The pet trade has been responsible for many introductions of non‐native species. Freshwater ornamental plants and animals originating from the pet trade are stocked to garden ponds. The present survey focused on awareness and responsible behaviour related to biological invasion risks of companies that designed, built, and stocked garden ponds.
2. A representative number (n = 124) of companies (commercial garden pond architects and builders) in the Czech Republic were surveyed regarding the offer of non‐native, invasive and threatened native species. The survey was conducted over the entire warm period (from 1 May 2015 to 31 September 2015) while using personal visits, correspondence and interviews to list the species on offer.
3. ‘Traditional’ ornamental species were offered by 39.1% of surveyed vendors, non‐traditional ‘marginal’ species by 5.6%, common native species by 6.5% and threatened native species by 2.4%.
4. The findings of this study support the hypothesis that ‘garden pond’ vendors offer non‐native species with a risk of biological invasion; moreover, threatened native animals were also on sale. It is probable that a similar situation exists in other countries. It is important for the conservation of native aquatic biota to raise awareness of the need to reduce risk through responsible behaviour of those involved in the pet trade. It is also essential to prohibit stocking of potential invaders and to enforce the illegal capture and sale of native species.

     

Science,capacity building and conservation knowledge: The empowerment of the local community for marine conservation in Rapa Nui

1. Marine protected areas have been scaling up from small areas located in coastal waters to large‐scale marine protected areas in remote areas, partly in response to the international agenda to conserve 10% of marine and coastal areas.
2. Chile has made considerable progress in the designation of large‐scale marine protected areas in its oceanic islands with varying degrees of top‐down and bottom‐up processes, scientific knowledge and interplay among institutions.
3. The process of designating the multiple‐uses marine protected area in Rapa Nui (Easter Island) involved interplay among scientific research, capacity building, local knowledge and collaboration between sectors, which contributed to the community transformation toward marine conservation in Rapa Nui.
4. A recent increase in scientific research on the marine ecosystems was transmitted to stakeholders and the local community via capacity‐building actions. The knowledge‐based empowerment of the Rapanui population (inhabitants of Rapa Nui) involved the definition not only of the objectives, the extension and the conservation goals of the Rapa Nui multiple‐uses marine protected area, but also of the implications beyond the designation, such as issues of governance, management and financing.
5. The implementation of the Rapa Nui multiple‐uses marine protected area will test local and Rapanui government relationships. The continuous science‐knowledge‐based dialogue in a strengthened relationship between the government and the local community in a ‘process of relating’ might be the pathway to future effective conservation efforts and successes.

     

Drivers of consensus‐based decision‐making in international environmental regimes: Lessons from the Southern Ocean

1. The global environmental crisis (characterized by declines in biodiversity, transboundary pollution, habitat degradation, and climate change) has inspired international environmental regimes, such as the Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR), to establish large‐scale networks of marine protected areas (MPAs) in areas beyond national jurisdiction.
2. The Southern Ocean surrounding Antarctica comprises roughly 10% of the global ocean and plays a crucial role in regulating global climate and marine ecosystems. Although the Antarctic marine environment currently remains one of the most intact on Earth, it is threatened by fishery expansion and a rapidly changing climate. In response, CCAMLR has been developing a representative network of MPAs to sustain ecosystem structure and function, protect areas vulnerable to human activities, and conserve biodiversity.
3. Whereas significant research has focused on the role of formal mechanisms and state power in international environmental regimes, very little is known about the role of non‐state actors and informal approaches, particularly in the negotiation of agreements to establish large‐scale networks of MPAs.
4. Case analysis of the 2016 Ross Sea Region MPA agreement reveals that CCAMLR is undergoing a significant period of learning and institutional evolution, as actors seek novel ways to negotiate a network of Southern Ocean MPAs. Key drivers of consensus include external political dynamics, internal leadership and group dynamics, and shared concern for the future of CCAMLR and Antarctic MPAs.
5. Actors also rely on informal principles of negotiation (such as increasing transparency, developing trust, and engaging in dialogue) to fill institutional gaps in both CCAMLR's formal structure and the current process for developing and negotiating MPAs.
6. As environmental threats grow in complexity and scale, non‐state actors and informal negotiations will become increasingly critical to support the ongoing success of formal international institutions dedicated to protecting the ecological integrity and function of the global environment.

     

New invasive predator reduces the abundance of native prey in a cold-temperate marine fouling community

1. Invasive species threaten the conservation of marine environments, and urgent management strategies are needed to prevent their introduction, establishment and spread. Specifically, marine invasive predators destabilize ecological interactions and alter community structure and function. However, most of the evidence showing the effect of these predators is restricted to a few species and regions, while for others the information remains scarce.
2. This study experimentally evaluated the ecological effects of the sea slug Pleurobranchaea maculata, a recently introduced invasive predator, on the fouling communities of a cold-temperate port in the South-western Atlantic.
3. The results show that increasing predation pressure reduces significantly the abundance of sea anemones, which are among the preferred prey items.
4. This study reveals new evidence to help better understand the effects of P. maculata on the biological communities of a recently invaded region. Furthermore, it provides the first experimental evidence supporting the hypothesis that marine invasive predators can induce a significant decrease in the abundance of native species in benthic communities of cold-temperate marine environments in the South-western Atlantic.

     

Measuring responses of harbour seals to potential aversive acoustic mitigation signals using controlled exposure behavioural response studies

1. Some anthropogenic activities pose acute risks for marine species. For example, pile driving could damage the hearing of marine mammals while underwater explosions can also result in physical damage or death. Effective mitigation is required to reduce these risks, but the exclusion zones specified in regulations can extend over hundreds or thousands of metres and seals pose particular problems because they are difficult to detect at sea.
2. Aversive sound mitigation aims to exclude animals from high‐risk areas before dangerous activities take place by broadcasting specific acoustic signals. Field research is needed to identify signals that might be effective in eliciting short‐term avoidance by marine species such as harbour seals (Phoca vitulina). A series of controlled‐exposure experiments (CEEs) were undertaken to measure seal movements in response to acoustic deterrent devices (ADD) and predator calls, and to assess the effectiveness of candidate signals for aversive sound mitigation.
3. Seals were fitted with UHF/GPS transmitters providing continuous high‐resolution tracks and real‐time transmissions of their locations. A tracking/playback vessel located seals at sea and transmitted either ADD signals or orca (Orcinus orca) calls over a range of distances while seals were foraging or moving between sites. Behaviour before, during and after exposure was analysed to assess responses.
4. One‐hundred and ten CEEs were assessed as being of at least ‘adequate’ quality. Of the 71 adequate trials with the Lofitech ADD, all 38 at ranges of <1 km (predicted received level 134.6 dB RMS re 1 μPa) elicited a response. The maximum response range was 3123 m (predicted RL: 111 dB RMS re 1 μPa). However, the responses observed did not always result in substantial movements away from the source, especially for seals that were travelling at the time of the exposures. More work is needed to better understand how exposure risks would be reduced in different scenarios.
5. The mean net speed of horizontal movements for seals responding to aversive sounds (1.15 m s^?1) was only 7% higher than their mean travel speed.
6. Responses to broadcasts of orca calls were highly variable.
7. The results suggest that signals similar to those generated by a Lofitech ADD could be used to reduce risks to harbour seals from pile driving and underwater explosions in coastal waters. More work will be needed to develop systems that match the requirements of industry and regulators and to explore whether these results can be generalized to offshore waters and to other phocids.

     

Antarctic silverfish: life strategies of a key species in the high‐Antarctic ecosystem

Among the endemic notothenioid fish of Antarctica, the Antarctic silverfish (Pleuragramma antarcticum) is the only species in which all developmental stages live throughout the water column. It is widely distributed in the shelf waters around the continent, inhabiting both open waters and areas of pack ice at depths from 0 to 900 m. In successfully occupying this habitat, it evolved a suite of specific biological, ecological and physiological adaptations to the environmental conditions in the cold and highly seasonal Antarctic waters. Specialization for the pelagic environment evolved over millions of years enabled life under unusual environmental constraints and colonization of the pelagic realm of the Antarctic continental shelf. A sudden change of environmental conditions driven by the current rapid climate change could negatively affect this weak equilibrium, with a catastrophic cascade effecting higher trophic levels. Indeed, as both adults and early life stages of the Antarctic silverfish appear to be strongly dependent on sea‐ice, this species would be especially sensitive to climatic or oceanic changes that reduce the extent of sea‐ice cover or the timing of formation of coastal polynyas.     

Indo‐Pacific humpback dolphins (Sousa chinensis) in the Moyang River Estuary: The western part of the world's largest population of humpback dolphins

1. Information gaps from uninvestigated habitats can hinder population assessments and the efficacy of conservation actions for marine mammals, particularly for populations of widely distributed species. The full extent of occurrence of the world's largest (putative) population of Indo‐Pacific humpback dolphins (Sousa chinensis) in the Pearl River estuary (PRE) is not known due to a poor understanding of the western boundary of the population's range. This information gap is the basis of the most critical obstacle for assessing the population's status.
2. To determine the distribution and abundance of the PRE humpback dolphins in the far western portion of its range, systematic line‐transect vessel surveys were conducted in the Moyang River estuary (MRE) during 2013–2015. Photo identification of dolphins and cross‐matching of individual dolphins between different regions were also undertaken to examine individual movement patterns.
3. The abundance of humpback dolphins in the MRE was estimated to be 528 individuals (coefficient of variation: 28.7–50.2%).
4. Cross‐matching of individually identified dolphins from the MRE (present survey area) with those from other survey areas of the PRE showed that dolphins moved frequently across different regions of the PRE, indicating dolphins from both PRE and MRE comprise a single population (which is renamed to be the PRE–MRE population). The western boundary of this population appears to be in the waters on the eastern side of Hailing Island, as dolphins were never observed further west.
5. Supporting around one‐fifth of the PRE–MRE population and providing a quarter of the habitat of the entire PRE–MRE population, the MRE clearly also deserves consideration for greater conservation measures. Strengthening the management with stringent controls over fishing activities in the MRE and establishing a marine protected area in the core habitat are recommended to facilitate better conservation for the entire PRE–MRE humpback dolphin population.

     

Interactions between Unionida and non‐native species: A global meta‐analysis

1. Understanding the multiple agents of decline is important for the conservation of globally threatened Unionida (Class Bivalvia), but threats from non‐native species have received limited attention. To address this gap, a global meta‐analysis was conducted aimed at identifying known interactions and mechanisms of impact and informing potential effect pathways for the New Zealand unionid fauna.
2. The main non‐native groups identified as interacting with unionids were fish (38% of published studies), macrophytes (33%), and vertebrate predators (30%), with ~70% of interactions leading to adverse impacts on mussels. Most studies used field surveys (~50%) and were conducted in rivers (~50%).
3. Impacts occurred across the unionid life cycle (adult, glochidia, host, and juvenile), and primarily affected processes that determine the transitions between life‐cycle stages (fertilization, infestation, settlement, and maturation). The impacts of non‐native macrophytes and fish were predicted to be greater for transitional stages than the impact of vertebrate predators, which mostly affected adult mussels.
4. New Zealand Unionida are most likely to be affected by interactions with non‐native species in lowland lakes and waterways, where connectivity for diadromous native fish hosts and high bioinvasion potential intersect.

     

The status of marine biodiversity in the Eastern Central Atlantic (West and Central Africa)

1. The status of marine biodiversity in the Eastern Central Atlantic (ECA), especially of coastal and pelagic fishes, is of concern owing to a number of threats including overharvesting, habitat loss, pollution, and climate change combined with inadequate policy responses, legislation, and enforcement.
2. This study provides the first comprehensive documentation of the presence, status, and level of extinction risk, based on IUCN Red List assessment methodology, for more than 1800 marine species, including all taxonomically described marine vertebrates (marine mammals, sea turtles, seabirds, fishes); complete clades of selected marine invertebrates (sea cucumbers, cone snails, cephalopods, lobsters, reef‐building corals); and marine plants (mangroves, seagrasses).
3. Approximately 8% of all marine species assessed in the ECA are in threatened categories, while 4% are listed as Near Threatened, 73% are Least Concern, and 15% are Data Deficient. Fisheries and overharvesting are the biggest threats to living marine resources in the ECA, with 87% of threatened species across all taxonomic groups affected by both large‐ and small‐scale targeted fisheries, excessive capture as by‐catch, or unsustainable harvest.
4. The results of this study will transform the current state of knowledge and increase capacity for regional stakeholders to identify and enact marine conservation and research priorities, as a number of species are identified as having high conservation and/or research priorities in the region.
5. Through the process of marine species data collection and risk assessments conducted over the past 5 years, several key conservation actions and research needs are identified to enable more effective conservation of marine biodiversity in the ECA, including increased governance, multilateral collaboration, taxonomic training, and improved reporting of fisheries catch and effort.

     

Migratory connectivity and local site fidelity in red knots on the southern Pacific coast of South America

1. The red knot Calidris canutus, a flagship migratory waterbird species, continues to decline within the Americas. One major unanswered question is the status and connectivity of birds spending the non‐breeding season on the southern Pacific coast of South America. Answering this question will provide a useful geographic endpoint that could enhance ongoing conservation efforts.
2. Red knots on Chiloé Island (43°S, Chile) were studied during four consecutive non‐breeding seasons (2014–2018) using systematic counts and resightings of ringed individuals in two shallow bays with known aggregations of other shorebird species.
3. Maximum seasonal abundances (±SD) at each bay (68.8 ± 13.4; 85.0 ± 13.2) were similar across years. However, actual abundance on Chiloé is probably higher, as other suitable habitats were not surveyed.
4. A total of 55 resightings corresponding to 14 individuals were recorded. The majority (72%) was for birds present during consecutive seasons; there were no recorded interchanges between bays. All birds, but one in Argentina, were ringed on the Atlantic coast of the USA (mainly the Gulf of Mexico) during their spring (northward) migration.
5. Mark–resight data reveal a strong migratory connectivity between the southern Pacific coast of South America and the Atlantic coast of North America for this small but regular population of a highly imperilled species. Data also suggest that the red knots on Chiloé might be considered a separate conservation unit (most likely subspecies rufa). Thus, there is an urgent need to conduct comprehensive studies on Chiloé Island for the conservation of the intraspecific diversity of this migratory flagship species.

     

Influence of seasonality on cetacean diversity,abundance, distribution and habitat use in the western Mediterranean Sea: Implications for conservation

1. Cetaceans are key biological indicators of the status of marine waters and are protected under an extensive legislative framework. Research about these highly dynamic species is challenging, so seasonal cycles and patterns of distribution, especially in high sea areas, are still poorly understood.
2. This study contributes to improving knowledge about cetacean occurrence in largely unexplored areas of medium‐latitudes in the western Mediterranean Sea. Systematic surveys were conducted along a trans‐regional transect over 3 years (October 2012 to September 2015) allowing consistent data collection over almost 60 000 km of effort through all seasons.
3. Seasonal cetacean diversity was investigated using a 25 km² grid cell as a statistical unit to explore patterns of abundance, distribution, and habitat use in three marine sectors (Sardinian–Balearic, Bonifacio Strait, Tyrrhenian). All cetacean species regularly present in the Mediterranean basin were detected, with highest occurrence in fin whale and striped dolphin, followed by bottlenose dolphin and sperm whale.
4. The Sardinian–Balearic sector generally showed higher species richness and diversity than the Tyrrhenian, where seasonal variations were more pronounced. The study suggested seasonal movements, especially for fin whale and striped dolphin, in the Sardinian–Balearic sector with peaks of occurrence during spring/summer and lower numbers during winter/autumn, and also delivered interesting insights to rarer pelagic species.
5. The study identified areas/seasons in which the combined effect of high species diversity, abundance, significance of hot spots and presence of juveniles require increasing conservation effort. Results underline the important contribution of continuous monitoring in high sea areas to the implementation of adaptive protection measures.

     

From the lab to the river: Determination of ecological hosts of Anodonta anatina

1. Coextinction is the simplest form of secondary extinction and freshwater mussels (Bivalvia, Unionida) may be particularly prone to this phenomenon as their life cycle includes an obligatory parasitic larval stage on fish hosts.
2. The main aims of this study were to determine the possible ecological fish hosts of Anodonta anatina (Linnaeus, 1758) in several rivers of the Douro basin in northern Portugal and to assess possible spatial and temporal differences in glochidial (larval) loads. In order to achieve this, electrofishing was conducted from December to April, the fish fauna was characterized, and levels of infestation with A. anatina glochidia were determined.
3. Native cyprinid species, mainly Luciobarbus bocagei (Iberian barbel) and Squalius carolitertii (northern Iberian chub), together with the non‐native Lepomis gibbosus (pumpkinseed sunfish) and Alburnus alburnus (common bleak), were found to have the highest glochidial loads. Clear differences in infestation between rivers and throughout time were detected, with an infestation period from January to March, and with the Tâmega River having the highest prevalence.
4. Anodonta anatina is able to infest a variety of fish species, and this together with earlier studies showed that the metamorphosis into juveniles occurs mainly in native cyprinid species, although non‐native species like common bleak can also be considered suitable hosts. However, the larvae infesting other non‐native species, such as the pumpkinseed sunfish, do not metamorphose and can be considered ‘dead ends’.
5. Overall, the results reported here are important for the conservation of A. anatina (and other unionoid species) because several Iberian rivers (and worldwide) have been subjected to the extirpation of native fish species and the introduction of non‐native fish species. Therefore, careful assessments of fish communities should be conducted to assess possible negative interactions with freshwater mussels.

     

Effect of an intensive mechanical removal effort on a population of non‐native rainbow trout Oncorhynchus mykiss in a South African headwater stream

1. Invasions by non‐native species can compromise the conservation value of otherwise pristine headwater streams. While both developed and developing countries recognize this threat, few of the latter have suitable budgets to implement control programmes.
2. This study assessed the effectiveness of a mechanical project to remove non‐native rainbow trout Oncorhynchus mykiss from a 6 km section of the upper Krom River, a small headwater stream in the Cederberg Mountains in South Africa's Cape Floristic Region (CFR).
3. From October 2013 to February 2014, 354 O. mykiss were removed by angling (58%), fyke netting (28%) and gill netting (14%). This resulted in a marked reduction, but not eradication, of the O. mykiss population (fish relative abundance decreased from 0.53 ± 0.09 fish per net per night in October 2013 to 0.21 ± 0.09 fish per net per night in February 2014). Following the cessation of manual removals, the relative abundance of O. mykiss had increased to 0.56 ± 0.18 fish per net per night by March 2016, suggesting that without sustained removal effort, the population will rapidly return to its pre‐removal abundance level.
4. Further work is needed to refine the methodology and test the effectiveness of mechanical removal of non‐native freshwater fish in a variety of ecological settings in the CFR. This approach holds potential for meeting the dual goals of reducing the ecological impacts of non‐native fishes and generating employment opportunities in line with the policy objectives of developing nations.

     

Freshwater ecosystem vulnerability: Is native climatic niche good enough to predict invasion events?

1. The introduction of invasive species is a significant threat to freshwater ecosystems and is changing the biogeographic patterns of fish species, leading to homogenization of fish fauna. The ability to predict potential invasions is critical in conservation biology to avoid further biodiversity loss.
2. Ecological niche modelling has become an important tool in biological invasion studies. However, some introduced species can spread to habitats that are different from those in their native range.
3. A framework based on niche shifts and ecological niche models was used to show that Pterygoplichthys ambrosettii, an armoured catfish, commonly known as ‘pleco', and native to the middle‐lower Paraná river, has expanded its niche by 27% and is now occupying a new range of environmental conditions.
4. This species has experienced a niche shift from its original habitat and has started to occupy new areas of the Upper Paraná river basin and the São Francisco basin in Brazil. Models built using both native and non‐native areas were not able to predict the invaded habitats, and in either the native or non‐native areas the cross‐validation procedures corroborate the niche expansion hypothesis.