Potential distribution and population trends of the smalltail shark Carcharhinus porosus inferred from species distribution models and historical catch data

1. Updated distribution ranges are crucial for conservation status assessments. Comprehensive analyses combining published literature and available data on historical catches and species distribution models (SDMs) are effective tools that could improve the prediction of more realistic scenarios for some species, especially those with limited information available and facing multiple threats.
2. The present study aimed at generating an updated distribution for the smalltail shark Carcharhinus porosus, one of the most threatened and understudied shark species of the western Atlantic Ocean. Estimates of the key areas for this species conservation based on the SDMs, and trends in catch probabilities throughout its distribution range are provided.
3. Four algorithms (BIOCLIM, Domain, Mahalanobis, and Maximum Entropy) were used to model the distribution of C. porosus and calculate its habitat suitability based on marine environmental variables. To assess historical catch probability trends, we built a generalized linear model from published and grey literature data. This analysis was used to estimate catch probability as an indication of population trends.
4. SDMs suggest that the northern coast of South America (NCSA) harbours the most suitable habitats for C. porosus in the world, which was expected given its historically high catch rate in this region. In addition, there was a continuously declining catch probability trend starting in the 1970s. However, the decline was smaller for the NCSA as compared with the Gulf of Mexico and the eastern South America coast.
5. Results indicate that the NCSA should be considered the currently most important area in the world for this species conservation. Furthermore, the lack of data throughout Central and South American marine regions hampers the evaluation of extinction risk throughout its updated distribution. Thus, research in these areas is urgently required for a more comprehensive conservation status assessment.

     

Gene pool and connectivity patterns of Pinna nobilis in the Balearic Islands (Spain,Western Mediterranean Sea): Implications for its conservation through restocking

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Population status of the endangered giant Mexican limpet Scutellastra mexicana in the central Mexican Pacific

1. Scutellastra mexicana is the largest species of giant limpet in the world. This species is distributed along the tropical Mexican Pacific and is now considered extinct in some areas of the region.
2. In prehispanic Mexico, this limpet was used for food, ornamentation, and in mortuary offerings. More recently, its meat has been highly valued for human consumption. During the 1970s and 1980s, overexploitation of this resource caused the population to decrease drastically.
3. This study is a report on the population status of the giant Mexican limpet S. mexicana on the Mexican Pacific coast. Free divers explored the rocky southern coast of Jalisco, Mexico, for the presence of specimens. A total of 404 limpets were identified at 18 sampling sites. Their density was estimated to be 0.0012 limpets/m² with a catch per unit effort of 7.6 limpets/dive hour. Limpet sizes ranged from 5.0 to 23.3 cm in length and from 3.8 to 20.7 cm in width, with a mean shell length of 13.4 cm.
4. Currently, S. mexicana is under special protection by Mexican laws. However, this species is not listed as endangered by any international wildlife protection and conservation group. This may be due to the lack of information on this species' population dynamics over time in the Mexican Pacific and the lack of interest in this mollusc since it is a non-charismatic species.

     

Demonstrating the practical impact of studies on biotic interactions and adaptation of a threatened unionoid mussel (Margaritifera margaritifera) to its host fish (Salmo trutta)

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.

     

How does summer environmental degradation influence native mussels in Corbicula invaded rivers?

1. Droughts and heat waves are becoming more frequent, persistent, and intense in a global warming context. Although previous studies reported Corbicula mass mortality events associated with the occurrence of extreme summer conditions, knowledge of their effects lags behind ecosystem functioning.
2. The goal of this study was to determine whether summer environmental degradation (droughts, extreme temperatures, and spikes in ammonium concentration) influences the survival and behaviour of native mussels in rivers invaded by Corbicula and, in consequence, their functioning in ecosystems.
3. Unio delphinus mussels were exposed to increasing summer environmental degradation. Water column and pore water samples were collected at six sampling time-points for nutrient analysis. Environmental conditions, survival and behaviour were monitored at 12-hour intervals.
4. Mortality risk was greatest under no-flow conditions, reaching 100% of mortality after 84 ± 22 hours of exposure to anoxic (<2 mg O₂ L⁻¹) conditions. At the sub-lethal level, quiescent conditions impaired filtration activity. In addition, when facing rising temperatures, native mussels buried deeply and vertical movements were depleted.
5. There were significant differences between the water column and the pore water in physicochemical characteristics. Oxygen and nitrate concentration were generally higher in the water column. In contrast, ammonium and phosphate maximum concentrations were measured in the pore water.
6. The results suggest that environmental degradation affects the role of mussels in ecosystem functioning. For instance, prolonged valve closure under poor water quality conditions may have impacts on particle removal from the water column. Furthermore, impairment of vertical movements may reduce nutrient release from sediments.
7. The present study has key implications for water management and for the conservation of mussel populations. For instance, a responsible approach for maintaining ecosystem integrity should include the water needs of freshwater mussels in environmental flow recommendations and the conservation of riparian vegetation corridors to mitigate the effects of increased water temperature in rivers.

     

Engaging recreational scuba divers in marine citizen science: Differences according to popularity of the diving area

1. Characterizing the composition of divers visiting different diving areas could help to design marine citizen science (MCS) projects that support biodiversity monitoring and marine conservation.
2. Recreational scuba divers mostly prefer warm and clear waters with coral reefs, and based on the Duffus and Dearden’s wildlife tourism framework we hypothesized that a more popular diving area is visited mostly by generalist divers, whereas in a less popular diving area a higher proportion of specialist divers would be found.
3. Recreational scuba divers were surveyed in diving centres at two diving areas, Rapa Nui (more popular, with warm and clear coral-reef waters) and the Chilean mainland (less popular, with productive and temperate–cold waters), to determine their diving profile, visiting profile, marine species knowledge, and interest and participation in MCS.
4. Support for our hypothesis (generalist divers on Rapa Nui and specialist divers on the mainland) was weak, but recreational divers on Rapa Nui were mostly foreign visitors who come for single visits, whereas divers from the mainland were predominantly Chileans who return repeatedly to the diving area. In both diving areas the divers expressed a strong interest to be trained and to participate in MCS, but divers from Rapa Nui were interested in brief pre-dive inductions, whereas divers from the Chilean mainland preferred intensive training courses.
5. Based on these findings we recommend specific MCS strategies for divers in both types of areas, e.g. simple protocols in more popular diving areas, with short pre-dive briefings for divers, and medium or long-term programmes in areas where most divers are local with high return rates. In these latter conditions more extensive training will be useful, which allows divers to gain more experience and assume higher responsibilities within an MCS project.

     

Freshwater mussels in Mediterranean-climate regions: Species richness,conservation status,threats, and Conservation Actions Needed

1. The five global Mediterranean-climate regions are experiencing alarming rates of freshwater biodiversity loss. Although freshwater mussels are recognized as important functional components in aquatic ecosystems, and are among the most threatened faunal groups globally, there has been no synthesis of the plight of this group within these regions.
2. Data from the International Union for Conservation of Nature (IUCN) Red List were reviewed to compare the conservation status, threats, and conservation actions needed for freshwater mussel species occurring in Mediterranean-climate regions (med-mussels) with those of other freshwater mussel species globally. The first comprehensive catalogue of med-mussel species was compiled using existing taxonomic literature.
3. There are 41 med-mussel species, 30 of which occur in the Mediterranean basin. Many regions have just a single species, and regions where multiple species occur generally only have between one and four species per river basin. Med-mussel species are almost twice as likely to be ‘Imperilled’, are affected by 2.4 times more threats, and require 3.5 times more conservation actions than non-med mussels. In many cases, the exact threats have not been identified.
4. In combination with low species richness, this level of imperilment means that Mediterranean-climate regions are at risk of losing the benefits that mussels provide to broader ecosystem functioning. The conservation of med-mussels can be improved by increasing our knowledge of species distributions, including the identification of cryptic species and significant management units, through population genetic work. In addition, recognizing the potential of ‘novel’ habitats and refuge areas could augment the management of this important functional group.

     

From Linderiella baetica to gambilusa: Involving children in conservation by giving a new species a common name

1. The knowledge and awareness that the general public has about aquatic invertebrates is often poor, even when they are highly threatened. The frequent lack of popular names and the unattractiveness of the scientific ones may be among the factors hindering the knowledge of these organisms and, consequently, the awareness of their conservation status and the willingness to conserve them.
2. Linderiella baetica (Crustacea, Branchiopoda, Anostraca) was discovered in 2007 in southern Spain and is considered a critically endangered species. However, being a small invertebrate inhabiting generally unappreciated temporary ponds, this species was completely unknown by the general public, even in the area in which it occurs.
3. To increase the knowledge and awareness of L. baetica, 1,347 children from five schools within its distribution area participated in a contest to select a common name for this newly described taxon. The winning name, gambilusa (Andalusian shrimp), will be used in the future by the Spanish Ministry of Environment and hopefully by the general public to identify the species.
4. The contest was found to have increased the knowledge about the target species in a sustained manner, as 1 year later, 93% of the children recognized gambilusa as a crustacean, 75% remembered its typical habitat, and 89% broadly identified its geographical distribution.
5. This kind of name-choosing contest is applicable for different regions and taxa to raise awareness on the conservation of threatened but poorly known biota.

     

Fishing and trade of devil rays (Mobula spp.) in the Bay of Bengal,Bangladesh: Insights from fishers’ knowledge

1. Devil rays (Mobula spp.) are globally threatened cartilaginous fishes that have attracted global conservation concern owing to their high extinction risk and lack of protection in many countries. Limited resources and data on threatened marine species, including devil rays, impede conservation actions, particularly in developing countries, many of which have high biodiversity.
2. Devil ray catch is a component of artisanal fisheries in Bangladesh, but data on their fisheries and trade are limited. To characterize devil ray fishing practices, fishers’ perception and trade, 230 fishers and traders were interviewed between 4 June 2018 and 22 June 2019, in four areas of south-east Bangladesh. Catch data were also opportunistically collected at landing sites.
3. Six devil ray species were documented, caught in an array of gill nets, set-bag nets and longlines. All interviewed fishers reported life-long devil ray bycatch in some numbers, and also noted a decline in catch over the last decade. Bottom trawling, increased bycatch levels, increased demand for devil ray products and, in some cases, ecosystem changes were identified by fishers as threats to devil ray populations.
4. Unregulated and undocumented trade and retained bycatch, especially by gill nets and set-bag nets, are fuelled by local consumption of devil ray meat and international trade in meat and gill rakers. Compliance with international trade control treaties for all Mobula spp. or the Bangladeshi law protecting Mobula mobular was low, with the majority of fishers (87%, n = 174) unaware of their existence.
5. To manage devil ray fisheries, and prevent possible population declines, we propose a combination of legally enforced gear modifications, and catch and trade control through community-owned implementation strategies. Additionally, we propose the simultaneous implementation of inclusive, community-based awareness and stewardship projects in conjunction with a coast-wide ray monitoring programme. Finally, we emphasize that more research and action rooted in a sustainable fishery model is urgently needed to protect Bangladeshi devil ray populations.

     

High‐resolution ecological niche modelling of threatened freshwater mussels in east Texas,USA

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Determining home range,changes in habitat use with time,and the threats to an endangered freshwater turtle (Rafetus euphraticus) in Turkey

1. The Euphrates softshell turtle (Rafetus euphraticus) is the most threatened chelonian species in the Middle East, where it is endemic to the Tigris and Euphrates basins. Since the ecology of this species is little known, it is difficult to plan any reliable action for its correct management and conservation.
2. To enhance the scientific knowledge on R. euphraticus, and to establish a science-based management strategy, a detailed investigation was undertaken on the distribution, habitat, activity and home range of R. euphraticus in Turkey. The previous distribution records in Turkey are for the 1990s; thus, this study is the first comprehensive field research on the species after nearly 3 decades.
3. There was a significant sexual size dimorphism in the Turkish population, with males larger than females.
4. Four individuals were radiotracked for 1 year. The mean home range was highly variable depending on how it was calculated, but that of males was considerably greater than that of females by all methods used.
5. A quantitative evaluation was made of habitat change with time. The land cover classes potentially available to turtles in the Euphrates River basin increased by more than 100% between the 1990s and 2018: 92% of this enhancement was derived from water bodies and coastal lands.
6. Fifteen dams have been built in the lower part of the basins in the last 30 years. In addition, continuing human interactions have caused the fragmentation or destruction of suitable habitats for R. euphraticus.
7. The factors threatening R. euphraticus were assessed and a conservation action plan was developed. Some objectives such as monitoring and creating awareness of this action plan have been met while others are still waiting to be achieved.

     

Behavioural and metabolic responses of Unionida mussels to stress

1. The aim of this study was to assess the extent to which the behavioural traits of freshwater mussels provide suitable indicators of stress in individuals, towards the advancement of non-invasive, remote monitoring techniques to examine population condition.
2. Variation in the expression of particular behavioural metrics was examined in accordance with measurements of oxygen consumption, across environmental stressors (aerial exposure and high concentrations of total suspended solids), and between two freshwater mussel species (Margaritifera margaritifera and Anodonta anatina)
3. Aerobic metabolic rate was quantified using intermittent respirometry, and behaviour was observed using time-lapse footage. Comparisons of metabolic response and the occurrence of behavioural traits, across the two stressors, focused on differences between the 24 h pre-exposure period (pre-exposure), the first 3 h of post-exposure (immediate post-exposure), and the time following the initial 3 h of post-exposure until the end of the experimental run (extended post-exposure).
4. The results of this study demonstrated a relationship between the frequency of occurrence of behavioural responses to stress exposure, associated with valve activity, and significant changes in the metabolic functioning of A. anatina and M. margaritifera mussels. The findings from the study also highlighted substantial intraspecific variation across species and stressors.
5. Data from this research could assist in the development of novel biosensors that track mussel valve activity remotely in their natural environment. When coupled with real-time data examining alterations in environmental metrics, this technology could assist in the monitoring of population condition and aid conservation management.

     

Fisheries and conservation assessment of sharks in Pacific Panama

1. In Panama, shark fisheries were initially developed in the 1980s and progressively increased in production in the 1990s mainly due to the high demand for shark fins and meat from the international Asian market. Since then, and despite the exploitation rate (average 3,514 t year^–1) and endangered status of some species, shark fisheries have seldom been studied, and official statistics are general or incomplete and not suitable for the development of appropriate conservation and management strategies.
2. To understand the dynamics of shark fisheries in Panama, field surveys were conducted between 2007 and 2009 at several landing ports of small‐scale and industrial fisheries, at fish processing plants and on‐board fishing vessels in Pacific Panama, where most of the fishing vessels of the country operate.
3. In general, it was found that the artisanal and industrial fisheries of the Pacific coast of Panama regularly exploit at least 18 species of sharks, which are also being exploited by neighbouring countries in the eastern Pacific, suggesting the importance of coordinated conservation initiatives across the multiple jurisdictions. A large number of the individuals caught were immature, implying a certain level of impact on recruitment rates. This pattern was particularly evident in species such as Sphyrna lewini, for which immature individuals represented at least 99% and 63% of the total catch by small‐scale and industrial fisheries, respectively. Catch per unit of effort analyses showed that Carcharhinus and Sphyrna species were the most exploited (representing ~80% of the catches) by industrial fisheries in Panama between 2006 and 2009, suggesting that fishery management should provide special attention to these groups.
4. It is expected that the information presented here provides a baseline to develop new regulations, including the implementation of annual quotas and fishing seasons and the protection of nursery areas, for the long‐term sustainability and conservation of sharks in Panama.

     

Regular monitoring and targeted removals can control lionfish in Mediterranean Marine Protected Areas

1. A lack of biosecurity in the Suez Canal has combined with global warming and other human pressures to cause abrupt changes in the Mediterranean Sea. Throughout this region an influx of species is influencing the outcome of efforts to protect and restore nature.
2. Despite calls for targeted removals of invasive species from protected areas, there is limited information about the effectiveness of this course of action from both an ecological and a socio-economic perspective. In this study, coordinated removals of lionfish (Pterois miles) by volunteers/scuba divers at three marine protected sites in Cyprus were conducted.
3. The removal efficiency was monitored using visual-census surveys and citizen science data. Removals significantly decreased lionfish numbers but long-term suppression of lionfish would require monitoring and repetition of removals when necessary, since population recovery was sometimes rapid.
4. Citizen science yielded the data needed to understand lionfish population changes and guide the timing of removal events, but was characterized by large variation and potential outliers, highlighting the need for large sample sizes.
5. Questionnaire surveys were used to assess the social impact of participation in lionfish removals; these showed that involvement had a strong positive impact on knowledge about lionfish and motivation to support marine conservation activities – the divers were even willing to pay extra to remove lionfish.
6. Management reforms would be needed to capitalize on this societal motivation, and enable effective lionfish removals by scuba divers, coordinated by competent authorities. The EU aims to protect at least 30% of the marine waters by 2030. Removal events could help shield selected conservation sites from the adverse effects of lionfish and at the same time help establish links with local communities, strengthening the sustainable use of marine systems both at corporate and at societal levels.

     

Diversity,conservation status and threats to native oysters (Ostreidae) around the Atlantic and Caribbean coasts of South America

• 1. Despite the extensive literature on the ecology, systematics and culture of oysters worldwide, an assessment of their diversity, distribution and conservation status for the Atlantic and Caribbean coasts (i.e. depth <50 m) of South America is lacking. Such information is crucial because of the increasing coastal development that threatens most nearshore habitats throughout the region.
• 2. The available information on oysters on Atlantic and Caribbean coasts is reviewed with a focus on identifying regional conservation priorities based on ecological and socio‐economic importance, as well as the magnitude of current or potential threats faced by oyster populations. The current status of α‐ taxonomy within the Ostreidae was also examined.
• 3. Ten species of native Ostreidae (plus three introduced species) inhabit the coastal waters of the Atlantic and Caribbean coasts of South America.
• 4. Oyster species were ranked according to their biological/ecological and socio‐economic value and conservation status within 10 distinct ecoregions. Crassostrea gasar in the Eastern Brazil ecoregion, C. rhizophorae in the Central Caribbean ecoregion and Ostrea puelchana in the North Patagonian Gulfs ecoregion should receive the highest priority for immediate conservation action due to extensive loss of mangrove habitat in the two former regions and evidence of decline of one of the most important populations for the latter. The need for a standardized methodology to assess the status of oyster populations throughout the ecoregions is identified.
• 5. On a local scale, the allocation of territorial use rights for fisheries under a collaborative/voluntary community framework is strongly advocated to fulfil management, conservation and poverty alleviation goals in these developing countries.

Copyright © 2008 John Wiley & Sons, Ltd.     

Annual variation in recruitment of freshwater mussels and its relationship with river discharge

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Sandbar shark aggregation in the central Mediterranean Sea and potential effects of tourism

1. An aggregation of sandbar sharks Carcharhinus plumbeus occurs every summer around the remote uninhabited islet of Lampione (Pelagie Islands Marine Protected Area, south-western Mediterranean Sea), attracting an increasing number of tourists for a shark watching experience.
2. Despite the ecological and socio-economic importance of this rare occurrence in Mediterranean waters, there is a lack of scientific data and lack of information as to the potential impact of tourist activities on the presence and behaviour of this shark species.
3. Using baited underwater videos, this study provides the first assessment of this shark aggregation, as well as a preliminary evaluation of the potential effects that boating and diving activities may have on sandbar sharks during two different periods within the tourism season (July and September 2019).
4. Overall, 241 sandbar shark sightings (with up to five individuals together) were recorded in July, whereas there were only six sightings in September. The average MaxN was 1.18 hr⁻¹ (±0.21 hr⁻¹ SE) and 0.22 hr⁻¹ (±0.10 hr⁻¹ SE) individuals in July and September respectively. Higher frequentation levels of divers and boats significantly reduced the number of shark sightings at the aggregation site.
5. This study emphasizes the need for further investigations on Mediterranean shark aggregations and the implementation of specific conservation measures, such as an increase of protection level in Lampione and better enforcement, aside from strategies that promote sustainable tourism, including restrictions on the number of boats and divers’ visits per day. In the meantime, a precautionary approach aimed at regulating the interactions between tourists and sharks should be implemented through the application of a self-regulatory code of conduct for divers when sharks aggregate around the island.

     

A direct multiplex loop-mediated isothermal amplification method to detect three CITES-listed shark species

1. Species identification of sharks under catch or trade regulations is important for law enforcement and species conservation. Rapid detection of Convention on the International Trade in Endangered Species (CITES)-listed species is needed for on-site screening.
2. Species-specific primers were designed to target three mitochondrial genes (ND2, COI, and CytB) in both the simplex and multiplex loop-mediated isothermal amplification (LAMP) assay for the pelagic thresher shark (Alopias pelagicus), the bigeye thresher shark (Alopias superciliosus), and the scalloped hammerhead shark (Sphyrna lewini), respectively. Another primer set designed to target S. lewini was used for detection-limit testing of the LAMP assay.
3. The refined direct multiplex LAMP was used to detect the three CITES-listed shark species and omitted the lengthy DNA extraction process. A homogenizer was used to release the DNA from the shark tissues, and a simplex or multiplex LAMP reaction was conducted for 30 min in an incubator at 65°C using species-specific primer sets.
4. Positive LAMP reactions showed a colour change from pink to yellow, whereas negative reactions showed no colour change. Multiplex LAMP assays were performed using 84 samples, which successfully identified the target and non-target species and provided a fast (<1 h), simple, and reliable method to distinguish three CITES-listed shark species from the other non-target species, for either fresh or dry fin products.
5. Results of this study and the method developed will play a critical role in assisting fishery agencies and customs officials in identifying the illegal catch and trade of CITES-listed shark species.

     

Understanding fishing and conservation of the Pacific seahorse (Hippocampus ingens) in Sinaloa,Mexico, through local ecological knowledge

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Loss of natural coastline influences species diversity of anemonefish and host anemones in the Ryukyu Archipelago

1. Anemonefish and host anemones are distributed in the shallow waters of coral reefs, and thus their existence may be affected by coastal development. The Ryukyu Archipelago includes the Okinawa and Sakishima Islands; the former has experienced extensive land reclamation and drainage in coastal areas while the latter still mostly contains natural coasts. To consider the layout of protected areas needed to conserve diversity of host anemones and anemonefish in the Ryukyu Archipelago, the community structure and coexistence mechanisms of anemones and anemonefish were compared between Okinawa and Sakishima Islands.
2. Six species of anemonefish and seven species of host anemone are distributed in both islands. Among 15 species-pair interactions observed in six species of anemonefish in the Sakishima Islands, 14 were explained by the niche differentiation hypothesis and only one interaction was explained by the cohabitation hypothesis. In the Okinawa Islands, 13 interactions were explained by the niche differentiation hypothesis, one by the cohabitation hypothesis and one by the lottery hypothesis.
3. For both host anemones and anemonefish, β-diversity in the Okinawa Islands was lower and had a more nested structure than that of the Sakishima Islands. β-Diversity and its nestedness did not differ between the two regions excluding study sites adjacent to coastlines, suggesting that differences in the coastal environment affected the diversity of anemones and anemonefish in the Ryukyu Archipelago.
4. These results suggested that there is an urgent need to prioritize the conservation of reef edges, where species diversity is relatively higher than directly next to the terrestrial coastline in Okinawa Island. In the Sakishima Islands, where many natural coasts remain, a wider area from directly next to the coast out to the reef edge needs to be comprehensively protected to increase β-diversity.