Status of aquatic and riparian biodiversity in artificial lake ecosystems with and without management for recreational fisheries: Implications for conservation

1. Humanity is facing a biodiversity crisis, with freshwater-associated biodiversity in a particularly dire state. Novel ecosystems created through human use of mineral resources, such as gravel pit lakes, can provide substitute habitats for the conservation of freshwater and riparian biodiversity. Many of these artificial ecosystems are subject to a high intensity of recreational use, however, which may limit their biodiversity potential.
2. The species richness of several taxa (plants, amphibians, dragonflies, damselflies, waterfowl, and songbirds) was assessed and a range of taxonomic biodiversity metrics were compared between gravel pit lakes managed for recreational fisheries (n = 16) and unmanaged reference lakes (n = 10), controlling for non-fishing-related environmental variation.
3. The average species richness of all the taxa examined was similar among lakes in both lake types and no substantial differences in species composition were found when examining the pooled species inventory. Similarly, there were no differences between lake types in the presence of rare species and in the Simpson diversity index across all of the taxa assessed.
4. Variation in species richness among lakes was correlated with woody habitat, lake morphology (surface area and steepness), and land use, but was not correlated with the presence of recreational fisheries. Thus, non-fishing-related environmental variables had stronger effects on local species presence than recreational fisheries management or the presence of recreational anglers.
5. Collectively, no evidence was found that anglers and recreational fisheries management constrain the development of aquatic and riparian biodiversity in gravel pit lakes in the study region; however, the conservation of species diversity in gravel pit lakes could benefit from an increasing reliance on habitat enhancement activities.

     

Association between burrow densities of two Australian freshwater crayfish (Engaeus sericatus and Geocharax gracilis: Parastacidae) and four riparian land uses

• 1. Freshwater crayfish that burrow into river banks are likely to be affected by riparian land uses that affect soil conditions and vegetation cover. The aim of this research was to determine whether burrow densities of two crayfish species (Engaeus sericatus Clark and Geocharax gracilis Clark) were associated with riparian land use and vegetation type in three streams in south‐west Victoria, Australia.
• 2. Four riparian land‐use categories were studied on each stream: native forest blocks; thin strips of mature native vegetation, fenced, with pasture adjacent; riparian pasture areas, fenced, with no cattle access to the stream; pasture and cattle access to the water's edge. Crayfish burrows were counted and a range of water quality and riparian condition variables were measured.
• 3. Native forest areas were found to have more than twice the densities of freshwater crayfish burrows than other land uses, which did not differ. Native forest areas also had higher mean burrow mound heights but lower burrow activity levels. Riparian characteristics also differed between land uses. In particular, soil compaction was the lowest in native forest areas, which also had better riparian condition scores and water quality than pasture areas.
• 4. This study suggests that cattle grazing may have reduced populations of burrowing crayfish in these streams, and that subsequent fencing and the presence of remnant native vegetation may be insufficient to ameliorate these effects. Blocks of native forest that remain on these streams may act as an important refuge for these species in agricultural areas.

Copyright © 2005 John Wiley & Sons, Ltd.     

Freshwater mussel abundance predicts biodiversity in UK lowland rivers

• 1. Indicator taxa are widely used as a valuable tool in the assessment of freshwater biodiversity. However, this approach to identifying sites of conservation priority requires surveyors to possess expert taxonomic knowledge. Furthermore, sorting and microscopic examination of material can present logistical and financial constraints.
• 2. Comparisons were made between the taxon richness and the density of freshwater mussels (Bivalvia: Unionidae) from 30 sites in seven UK lowland rivers, ranging from ca 3 m to 50 m width and ca 0.5 m to 4 m depth. Where mussels occurred, taxon richness of other invertebrates was strongly correlated with both mussel density and mussel biomass. Overall mussel density was a better predictor of taxon richness than the density of any individual mussel species.
• 3. It is suggested that this association arises from the ‘keystone’ role that mussels play in many freshwater ecosystems. Local biota can benefit from the mussels' filtration, excretion, biodeposition and physical presence.
• 4. Using mussel abundance as a surrogate provides a rapid and straightforward alternative to conventional methods of assessing freshwater biodiversity. No expert knowledge is required and any standardized sampling technique can be used. Freshwater mussels are found throughout the world's lentic and lotic fresh waters and this approach therefore has the potential for widespread utility, especially where rapid comparisons of biodiversity are required between biogeographically similar regions. In addition, the results highlight the ecosystem‐level consequences of allowing the global decline of freshwater mussels to remain unchecked.

Copyright © 2007 John Wiley & Sons, Ltd.     

Assessment of a terrestrial protected area for the conservation of freshwater biodiversity

1. Freshwater ecosystems are essential to human well-being and most have high biodiversity. However, this biodiversity has been suffering severe declines owing to the expansion of human activities. Protected areas (PAs) are essential for biodiversity conservation and have proved to be successful in stopping species extirpation if managed properly. Unfortunately, they are usually focused on terrestrial biodiversity, leaving freshwater ecosystems aside.
2. The main goal of this study was to determine the influence of a PA (Montesinho Natural Park (MNP), Portugal) on freshwater biodiversity. Aquatic macroinvertebrates and fishes were surveyed, and biodiversity (richness, abundance, Shannon-Wiener diversity, and Pielou's evenness) and water quality (IASPT) indices were calculated inside, at the periphery and outside the MNP.
3. Results showed that the PA does not affect positively either water quality or the two faunal groups monitored. Macroinvertebrate communities were not influenced by the PA; however, the abundance of pearl mussel Margaritifera margaritifera was significantly higher and size was significantly lower inside the MNP. The richness and abundance of fish communities were significantly higher outside the MNP, except for trout Salmo trutta abundance which was higher inside the MNP.
4. Given these results, the MNP does not guarantee the safeguard of overall aquatic biodiversity and habitats and we propose an extension of MNP to downstream areas in order to increase the number of species (mostly cyprinids) under legal protection. This work demonstrates that terrestrial PA planning and management should also consider aquatic biodiversity to achieve successful conservation.

     

A new genus and two new,rare freshwater mussel (Bivalvia: Unionidae) species endemic to Borneo are threatened by ongoing habitat destruction

1. Most of the Bornean endemic freshwater mussel (Unionida) species known to date have not been recorded by science for the past 50 years or more, owing to a lack of research effort and presumed population losses.
2. This study assessed current patterns and recent changes in the diversity and distribution of freshwater mussels in north-eastern Borneo. Physical surveys and interviews were conducted at 24 sites, and anecdotal evidence for current or historical presence of mussels was collected for a further 13 sites.
3. Native species, i.e. Schepmania sp. and Khairuloconcha sahanae gen. & sp. nov., were only found in one small stream of the Kinabatangan River basin within the Gomantong Forest Reserve, whereas the non-native Sinanodonta cf. woodiana was common across the study area.
4. Molecular phylogenetics (five genes) of the native taxa, including comparative material from West Kalimantan and Sarawak, revealed: (i) the presence of a new genus with two new, rare species: Khairuloconcha lunbawangorum sp. nov. in the Limbang River basin and K. sahanae in the Kinabatangan River basin; (ii) that Khairuloconcha and Ctenodesma form the Bornean endemic tribe Ctenodesmini trib. nov.; and (iii) that Schepmania represents another Bornean endemic tribe Schepmaniini trib. nov.
5. Both Khairuloconcha gen. nov. species are known from a single stream each and are apparently restricted to forest stream habitats where they occur at very low densities. Schepmania appears to have a severely contracted range in the Kinabatangan and adjacent basins. We urgently call for full protection of the currently known sites of K. lunbawangorum and K. sahanae, and development of an action plan to save the Bornean freshwater mussel fauna.

     

Ecoacoustics as a novel tool for assessing pond restoration success: Results of a pilot study

1. Ecoacoustics is increasingly being used to monitor species populations and to estimate biodiversity in marine ecosystems, but the underwater soundscapes of freshwater environments remain largely unexplored in this respect. Few studies exist concerning the acoustic diversity of ponds, but because aquatic plants and many arthropods such as Coleoptera and Hemiptera are known to produce sound, there is potential to use ecoacoustic techniques to monitor changes in biodiversity and conservation value.
2. This pilot study compares the underwater soundscapes of recently restored open-canopy ponds and unmanaged highly terrestrialized ponds situated in an arable agricultural landscape of North Norfolk, UK, in order to assess the benefits of farmland pond restoration.
3. Daytime sound recordings were made for 10 min in each pond and analysed primarily for arthropod stridulations. In addition, six commonly used acoustic indices were calculated to assess the soundscape biodiversity between the unmanaged and the restored ponds. The stridulations of three diving beetle species (Dytiscidae) were recorded in tank studies to assess the potential for individual species recognition from underwater sound capture.
4. Sound-type richness and abundance, as estimated by visually and aurally identifying arthropod stridulation from spectrograms, were significantly higher in the restored open-canopy ponds compared with the unmanaged terrestrialized ponds. In addition, the acoustic indices ‘acoustic complexity’ and ‘biodiversity index’ were significantly higher in restored open-canopy ponds than in unmanaged terrestrialized ponds.
5. The three dytiscid water beetle species recorded in a tank were found to produce distinctive and recognizable sounds, indicating potential to create an audio reference library that could be used for automatic acoustic monitoring of freshwater arthropods.
6. Pond soundscapes are rich in biological information and this study suggests that, with further development, automated passive ecoacoustic monitoring could be an effective non-invasive technique for assessing pond conservation value and pond restoration and management success.

     

Potential impacts of agricultural development on freshwater biodiversity in the Lake Victoria basin

相似文献   

Small mountain reservoirs in the Alps: New habitats for alpine freshwater biodiversity?

1. Today, aquatic biodiversity suffers from many pressures linked to human activities, including climate change, which particularly affects alpine areas. Many alpine freshwater species have shifted their geographical distribution to colder areas, but a reduced availability of suitable habitats is also forecasted. New artificial water bodies could provide habitat enhancement opportunities, including small mountain reservoirs built to overcome a lack of snow during winter.
2. To investigate the role of reservoirs as a habitat for freshwater invertebrates, a case study was conducted on eight reservoirs in the Swiss Alps. The study aimed to compare the water quality and freshwater biodiversity of the reservoirs with those of 39 natural and newly excavated ponds. Data were collected on physico‐chemistry, freshwater habitat structure, and aquatic insects (dragonflies and aquatic beetles).
3. The study showed that the mountain reservoirs investigated did not differ from natural ponds in terms of surface area, conductivity, and trophic level. Similarly to natural ponds, reservoirs showed signs of impairment owing to surface run‐off carrying pollutants linked to ski tourism. They presented a low diversity of mesohabitats, and in particular lacked vegetation. Compared with natural ponds, the species richness in reservoirs was lower for dragonflies but not for beetles. At the regional scale, the community from the reservoirs was a subset of the natural ponds community, supporting 38% of the regional species richness for these two insect groups.
4. The results suggest that mountain reservoirs are likely to be important for biodiversity in alpine areas, both as habitats and as stepping stones for species shifting their geographical range. These water bodies can be enhanced further by some nature‐friendly measures to maximize benefits for biodiversity, including margin revegetation or the creation of adjacent ponds. Ecological engineering needs to be innovative and promote freshwater biodiversity in artificial reservoirs.

     

Do non-native ornamental fishes pose a similar level of invasion risk in neighbouring regions of similar current and future climate? Implications for conservation and management

1. Global trade in non-native ornamental species coupled with high connectivity among countries is well known to result in worldwide biological invasions, which pose challenges for the conservation and management of biodiversity.
2. There are few studies aimed at implementing management strategies that have examined differences in the potential invasiveness of non-native species between neighbouring political regions within the same ecoregion.
3. To compare the potential risk of invasiveness of non-native ornamental fishes with high commercial value in the river basins of two neighbouring regions of East and Southeast Asia, 32 extant and horizon species were screened with the aquatic species invasiveness screening kit (as-isk ) for the lower Pearl River basin (South China) and the Chao Phraya River basin (Thailand). Both regional (i.e. basin level) and combined risk-ranking thresholds were determined by receiver operating characteristic curve analysis.
4. Of the 32 species screened, 14 were categorized as posing a high risk and seven were categorized as posing a medium risk of being invasive in both regions, under current and future climate conditions. These species have a history of invasiveness and the climate of their native ranges is similar to that of the two study regions. Pterygoplichthys pardalis received the highest risk score in both regions. The risk ranks of 11 species differed between the two regions, based on either the combined or regional thresholds, and this was partly related to the different risk of invasiveness between the two regions, coupled with cognitive subjectivity among the assessors.
5. The results of the present study suggest that the invasion of non-native ornamental fish species could pose similar threats to biodiversity in neighbouring regions. This will serve to inform policy makers of neighbouring countries in the development of coordinated, mutually beneficial regulations and management strategies to enhance the conservation of native species.

     

Aquatic macroinvertebrates from littoral vegetated lakes in arid Patagonia: The influence of fish introduction on community structure

1. Wetlands in arid regions are characterized by their great heterogeneity, often including endemic species that contribute to regional aquatic biodiversity. In the Patagonian steppe, most lakes are naturally fishless and sustain a rich aquatic biodiversity, including endemics; however, many of these lakes have been stocked with Oncorhynchus mykiss (rainbow trout) during recent decades. The introduction of predatory fish into aquatic ecosystems naturally devoid of these organisms can produce profound alterations in the structure of the original communities and in the configuration of their biotic assemblages.
2. Aquatic invertebrates play important roles in both the structure and functioning of freshwater ecosystems, including their contribution to global biodiversity and their cascading effects across ecosystem boundaries.
3. The aim of this study was to assess the effect of introduced non-native fish on the pleustonic macroinvertebrate assemblage. Samples were taken from 10 shallow Patagonian lakes (five fishless and five stocked with fish) in two consecutive warm periods.
4. Lakes with fish had higher conductivity and phosphate values. Higher inter-annual differences were also observed in lakes with fish for phytoplanktonic chlorophyll a, nitrate, phosphate, conductivity, and water temperature.
5. The community structure (relative abundance of different taxa, species composition, and diversity index) was affected by the presence of rainbow trout, with the differences mainly driven by the relative abundance of Ostracoda, Hyalella, Chironomidae, and Haliplus species.
6. This approach can be used to assess the required conservation actions in shallow Patagonian steppe lakes, which have been listed as priority areas for waterbird conservation. Specifically, this study provides a baseline for monitoring future trends of the macroinvertebrate communities and for evaluating conservation and management efforts over time.

     

Fish fauna in Iberian Mediterranean river basins: biodiversity,introduced species and damming impacts

• 1. A basin approximation was used to analyse distribution patterns of different components of biodiversity (taxonomic richness, endemicity, taxonomic singularity, rarity) and conservation status of freshwater fish fauna in 27 Mediterranean Iberian rivers.
• 2. Basin area alone explained more than 80% of variation in native species richness. Larger basins featured not only a higher number of native species, but also more endemic and rare species and fewer diversified genera than smaller basins.
• 3. In contrast, smaller basins scored higher community conservation values, owing to their lower degree of invasion by introduced species.
• 4. The presence of dams was the most important factor determining the conservation status of fish communities, and it was also positively associated with the number of introduced species.
• 5. While the most important components of Iberian freshwater fish biodiversity are located in large basins, small unregulated basins feature better conserved fish communities.

Copyright © 2004 John Wiley & Sons, Ltd.     

A phylogenetic perspective on biodiversity patterns of Afrotropical freshwater crabs (Crustacea,Decapoda, Potamonautidae)

相似文献   

Assessing the diet of the endangered Beale’s eyed turtle (Sacalia bealei) using faecal content and stable isotope analyses: Implications for conservation

1. Turtles from Asia are on the brink of extinction with 53% of species considered endangered or critically endangered. Unfortunately, the ecology of many threatened species remains largely unknown.
2. In this study, the diet of the endangered Beale’s eyed turtle (Sacalia bealei) was investigated using two methods, visual faecal content analysis and stable isotope analysis.
3. Results from both methods indicated that S. bealei is highly reliant on riparian resources, especially fruits and terrestrial insects. Stable isotope data indicated that terrestrial resources made up around half (47–53%) of all assimilated food resources. These findings suggest that S. bealei facilitates energy flow from riparian forests to stream ecosystems. Moreover, S. bealei is likely to be a seed disperser for riparian plants.
4. This study represents the first application of stable isotope methods to examine the diet of Asian freshwater turtles and their resource use. We stress the importance of similar studies to improve our understanding of remnant turtle populations before they disappear as a result of human activities.

     

Influences of in-stream habitat and upstream land-use on site occupancy of the Kanawha darter (Etheostoma kanawhae): A narrowly distributed species from the New River (Upper Kanawha Basin)

1. Freshwater communities are threatened by the conversion of natural landscapes for urban and agricultural purposes. Changes to land use may disrupt stream nutrient and geomorphological processes and reduce water quality, increase sedimentation, and decrease habitat heterogeneity eventually leading to species loss and decreases in ecosystem productivity. Endemic species are frequently at greater risk of habitat-mediated fragmentation and extirpation due to their constrained distributions.
2. The Kanawha darter (Etheostoma kanawhae) is an understudied fish endemic to the New River Drainage in North Carolina and Virginia, USA. To investigate the potential effect(s) of land-use change on Kanawha darters, naïve occupancy was modelled using instream habitat characteristics and upstream forest cover.
3. Generalized linear models revealed that instream habitat and forest cover are reliable predictors of Kanawha darter site occupancy. Specifically, models demonstrated that occupancy increased in reaches with reduced stream width, velocity, and bedrock substrate but higher concentrations of coarse woody material. Kanawha darter occupancy was also positively associated with the extent of forest cover in upstream catchments.
4. Although Kanawha darters are not currently considered imperilled, most populations occurred in isolated reaches separated by large sections of unoccupied habitat. Continuing ex-urban development in riparian zones is likely to be the primary threat to Kanawha darters and other endemic species in this catchment. Resource managers and stakeholders should preserve forest cover in headwaters and occupied tributaries and protect or restore riparian zones along the main-stem South and North Forks of the New River to preserve high-quality habitat and enhance connectivity among isolated Kanawha darter populations.
5. As human populations in montane regions continue to grow, there is a need to understand how land-use change affects endemic freshwater species. This study further supports the importance of retaining forest cover as an effective strategy for protecting and restoring populations of endemic fishes in high-gradient streams.

     

Potential impacts of non‐native fish on the threatened mahseer (Tor) species of the Indian Himalayan biodiversity hot spot

1. Mahseer (Tor) fish species are critical components of locally adapted freshwater food webs across the Indian Himalayan biodiversity hotspot; however, multiple human stressors compounded by climate change have significantly depleted their populations over recent decades.
2. Mahseer species are now considered locally vulnerable or endangered in many regions. Hydropower projects in particular have fragmented populations, impairing genetic exchange, obstructing migratory paths, and changing the structure and functioning of riverine habitats, especially of formerly fast‐flowing rivers.
3. Worryingly, a literature survey and group discussions reveal that the increasing spread of non‐native fish species further compounds threats to mahseer and overall freshwater ecology. A better understanding of the current distribution, habitat requirement, and dispersal of non‐native fish is therefore essential to manage the growing threats to mahseer in the Indian Himalayan region.

     

Reconstruction of the historical distribution ranges of imperilled stream fishes from a global endemic hotspot based on molecular data: Implications for conservation of threatened taxa

1. Understanding historical distribution patterns of freshwater fishes prior to human impacts is crucial for informing effective strategies for biodiversity conservation. However, incomplete information on species occurrence records, the existence of cryptic species and sensitivity to small sample sizes limit the application of historical records in natural history collections as well as conventional species distribution modelling algorithms to infer past distributions of species.
2. This study used molecular data as an alternative and objective approach to reconstruct the historical distribution ranges of four stream fishes from the Breede River system in the Cape Fold Ecoregion, a global hotspot of imperilled endemic freshwater biodiversity in southern Africa.
3. The study used 249 occurrence records and 208 mitochondrial cytochrome b sequences to reconstruct the potential historical ranges of four taxa: Galaxias sp. ‘zebratus nebula', Galaxias sp. ‘zebratus Riviersonderend', Pseudobarbus sp. ‘burchelli Breede' and Pseudobarbus skeltoni.
4. All four taxa historically had broader distribution ranges across the Breede River system before human impacts, but they have suffered severe attrition as the main‐stem populations have been extirpated.
5. The severe decline in the historical ranges of these four taxa is a result of multiple impacts, particularly hydrological modification, habitat degradation and the introduction of non‐native species, which are also global challenges for freshwater ecosystems.
6. The approach presented in this study has great potential for reconstructing historical ranges of stream‐dwelling taxa from disparate regions where fragmentation has resulted from human‐mediated impacts. This information is crucial for identifying appropriate conservation strategies such as river rehabilitation and eradication of non‐native species, as well as guiding reintroductions and informing assisted gene flow where these are deemed necessary interventions.

     

Colonization and use of pine wood versus native wood in New Zealand plantation forest streams: implications for riparian management

• 1. Riparian management is becomingly increasingly recognized as an important tool for reducing harvesting impacts on plantation forest streams. To provide information for a riparian management decision support system, this study investigated effects of riparian tree type (plantation Pinus radiata D. Don versus four native species) on the development of epixylic biofilms, and colonization and feeding by invertebrates on wood at two contrasting stream sites in the central North Island, New Zealand.
• 2. Electron micrographs revealed a diverse microflora colonizing all wood types, which generally had similar ergosterol concentrations, microbial activity and algal biomass after 1–2 years immersion.
• 3. Wood type (pine versus native) did not have a significant effect on densities of total invertebrates or dominant taxa. Percentage abundance of some dominant invertebrate groups differed between wood species, apparently in relation to surface complexity, but overall physical habitat differences appeared to override any effects of wood type on community composition.
• 4. The mass of fine particulate material produced by larvae of the conoesucid caddis fly, Pycnocentria funerea McLachlan, differed significantly among wood species, but this was not related to whether the wood was from native trees or plantation pine.
• 5. Overall, the results indicate that local variations in habitat heterogeneity and differences in wood surface texture were more important than wood type in influencing epixylic biofilm development, and utilization by invertebrates. Alien pine wood generally provided habitat conditions and trophic resources during initial decomposition that were within the range of variation of native wood species expected to colonize riparian planting set‐backs in northern New Zealand pine forests.

Copyright © 2004 John Wiley & Sons, Ltd.     

Conservation of aquatic insects in Neotropical regions: A gap analysis using potential distributions of diving beetles in Cuba

1. Human activities are an increasing threat to Neotropical freshwater ecosystems, with the potential extinction of thousands of aquatic species. Despite this, knowledge about the effectiveness of protected area networks in protecting aquatic insects in this biogeographical region is very limited.
2. Cuba supports the highest diversity of aquatic insects in the Antilles, with a large number of endemics.
3. A gap analysis was conducted to assess the effectiveness of the National System of Protected Areas of Cuba (NSPAC) in the conservation of Cuban diving beetles (family Dytiscidae). This involved considering the areas with the highest potential species richness, estimated by using species distribution models with three different approaches (MaxEnt, Random Forest and Support Vector Machine), and the known localities of endemic species.
4. The highest potential species richness of Dytiscidae in Cuba is predicted to occur in the low–medium altitude of the eastern mountain areas. Although most of these areas occur inside the NSPAC, several areas of potential high species richness are currently unprotected. It is recommended that sampling programmes are carried out in areas with high predicted species richness to validate the species distribution models.
5. The distribution of three Cuban endemic species (Copelatus barbouri, Desmopachria glabella and Celina cubensis) lies completely outside of the NSPAC. Despite their conservation interest as threatened endemic species, they are currently unprotected.
6. To improve the conservation of freshwater biodiversity in Cuba it is recommended that (i) the NSPAC network is extended to protect areas supporting endemic species and those with the highest potential species richness that are currently unprotected, and (ii) a whole-catchment management approach, specifically to maintain natural flows, should be adopted, especially in the mountainous areas of eastern Cuba.

     

Evidence of fish spillover from freshwater protected areas in lakes of eastern Ontario

相似文献