Can a cow save a newt? The role of cattle drinking troughs in amphibian conservation

1. Amphibians are the vertebrate group experiencing the steepest global population decline and species loss. Habitat alteration and loss caused by the intensification of agriculture is among the main causes; however, in the past, amphibians have been favoured by traditional agriculture and husbandry as more terrestrial and aquatic habitats became available through land‐use diversification and the construction of artificial facilities for cattle watering. Troughs for cattle watering may represent the only permanent water points for amphibian reproduction in human‐modified landscapes.
2. The present study focused on Lissotriton vulgaris meridionalis, a semi‐aquatic salamander, subendemic and widespread in Italy, capable of colonizing artificial aquatic habitats. The main goal was to determine the importance of drinking troughs for the ecology and conservation of the species in a hilly area (Latium region, Central Italy) subjected to traditional livestock farming (i.e. Maremmana cattle).
3. Specifically, generalized linear models (GLMs) were used to analyse the effects of drinking trough characteristics (i.e. size, substrate, aquatic vegetation), landscape features (distance to the forest, forest cover, percentage of cultivated lands and infrastructural development, terrestrial connectivity) and intensity of management practices on the occurrence and abundance of the target species.
4. In the light of the present results, it is suggested that drinking troughs represent suitable surrogates for pristine habitats for L. vulgaris meridionalis. Hence, even man‐made aquatic habitats, associated with traditional husbandry, may help to sustain amphibian populations in landscapes where natural wetlands are scarce. The present findings are timely because of the lack of empirical data on the role of drinking troughs in amphibian conservation within rural socio‐economic scenarios, which may have been neglected in research and policy in favour of lakes, rivers and streams.

     

Invasive dynamics of the crayfish Procambarus clarkii (Girard, 1852) in the international section of the River Minho (NW of the Iberian Peninsula)

相似文献   

Demography of southern Australian bottlenose dolphins living in a protected inverse estuary

1. Assessments of demographic parameters are essential to understand the dynamics of wild populations, and for their efficient conservation and management. Here, sex‐specific abundance, apparent survival and temporary emigration of southern Australian bottlenose dolphins (Tursiops cf. australis ) in Coffin Bay (CB), South Australia, is investigated.
2. Results are based on capture–recapture modelling of photo‐identification data and molecular analyses of biopsy samples collected during boat‐based surveys between September 2013 and October 2015 in the inner and outer areas of CB.
3. The total super‐population of dolphins (including calves) using the entire study area (263 km²) was estimated with POPAN models at 306 (95% CI: 291–323), which included 71 (68–73) marked females and 57 (55–60) marked males.
4. Seasonal estimates of abundance for the inner area of CB (123 km²) obtained with Pollock's Closed Robust Design models remained relatively constant over the two years (marked females: 52–60, marked males: 46–52, and total: 193–209).
5. The high density of dolphins inhabiting the inner area (seasonal range: 1.57–1.70 individuals km^?2), high apparent survival rates estimated for both sexes (females: 0.99; 95% CI: 0.96–1.0; males: 0.95; 0.82–0.99), and low temporary emigration rates (0.02; 95% CI: 0.01–0.11) indicate that the inner area of CB offers highly favourable habitat for these dolphins.
6. High biological productivity and low predation risk may promote these demographic patterns in the inner area of CB.
7. This study provides a robust baseline of sex‐specific population demographics of southern Australian bottlenose dolphins with important implications for future research and their management and conservation in South Australia.

     

Identification of essential habitats: Including chimaeras into current shark protected areas

1. Essential habitats are areas required to support specific functions, such as providing foraging grounds, shelter or used for reproductive purposes. For mobile aquatic species that move throughout numerous components of the seascape, identifying essential habitats within a species' broader distribution range is crucial to understanding their ecology and provide vital information needed to underpin effective conservation and management (e.g. the implementation of protected areas).
2. In Tasmania (Australia), a number of coastal habitats have been declared shark refuge areas (SRAs), where fishing for elasmobranchs (sharks, rays and skates) is prohibited.
3. Chimaeras are relatives of elasmobranchs (class Chondrichthyes) and share traits that predispose many elasmobranch species to be vulnerable to overfishing (e.g. slow growth rates and low reproductive output). However, fishing for elephantfish Callorhinchus milii (the chimaera species found in coastal Tasmania) is still permitted in SRAs.
4. Here, a combination of acoustic tracking, catch data and reproductive information was used to determine the significance of the SRA coastal habitats for C. milii.
5. Results suggest that these areas are essential habitats for reproduction and likely important for other purposes, such as foraging.
6. Given that a key strategy in managing fish stocks is protecting areas important for reproduction, and the importance of these coastal areas of Tasmania for C. milii reproductive purposes, we recommend including C. milii in current SRAs, and decreeing these areas as chondrichthyan refuge areas.

     

Managing invasive carp (Cyprinus carpio L.) for habitat enhancement at Botany Wetlands,Australia

• 1. In Australia, the carp Cyprinus carpio L. is regarded as a threat to the native fish and the aquatic environment. In recent years, Botany Wetlands, a significant coastal wetland in the Sydney region, has been invaded by the undesirable cyprinids, carp and goldfish (Carrasius auratus L.).
• 2. In 1996 a cyprinid removal programme commenced at Botany Wetlands with the objective of managing the invasive species, increasing fish diversity, reducing cyanobacterial blooms and hence enhancing the aquatic habitat. Using electrofishing and gill netting, 4073 carp and 261 goldfish, amounting to 10 117 kg of cyprinid biomass were removed between 1996 and 2004. The captured carp ranged from 60 to 835 mm. Males matured before females. Carp between 350 and 680 mm in length grew at the rate of 1.66±0.38 g day^?1.
• 3. The success of the programme was monitored by assessing four indicators related to carp populations and two related to habitat. The former included the pattern of length–frequency distribution, mean weight per size class, condition factor (CF) and the catch per unit effort (CPUE), and the latter the Secchi disc transparency and cyanobacterial counts. After 8 yr of removal, the plots of carp length–frequency distribution flattened, CF decreased from 2.86 to 1.82 and CPUE decreased from 97 kg day^?1 to 50 kg day^?1. A 10‐fold decrease occurred in cyanobacterial counts and the Secchi disc transparency increased by 20%. More than 20 000 fingerlings of native Australian bass Macquaria novemaculeata (S.) have been introduced to the wetlands, increasing the potential for juvenile carp predation and biodiversity.

Copyright © 2005 John Wiley & Sons, Ltd.     

Unintentional dispersal of aquatic invertebrates via footwear and motor vehicles in a Mediterranean wetland area

• 1. Several human activities, such as actions for nature conservation, research and recreational activities, are closely associated with inland aquatic habitats that are usually considered as isolated island habitats. In this study, the possibility of unintentional dispersal of aquatic invertebrates among water bodies via footwear and motor vehicles was investigated.
• 2. Mud samples collected from boots and from the tyres and wheel cases of cars used for field work by biologists (Camargue, Southern France) were hatched under laboratory conditions and also checked for the presence of unhatched propagules. A large number of organisms hatched and invertebrate propagules from a wide range of taxa were encountered (including Artemia, freshwater large branchiopods, Cladocera, Ostracoda, Rotifera, Turbellaria, Nematoda, etc.). The results also demonstrated that different research groups tend to transport the aquatic invertebrates typical for their respective study systems.
• 3. Human dispersal of aquatic invertebrates has been studied mainly on large continental scales, such as in the case of transoceanic transport via ballast water in ships. This study provides evidence that dispersal via footwear and motor vehicles may result in frequent dispersal of aquatic invertebrates on a local scale, and we presume also occasionally over longer distances. Given the rapid spread of invasive zooplankton species (e.g. Artemia franciscana encountered in this study), we promote caution and recommend cleaning before transport of any equipment which comes in contact with water or aquatic sediment. Copyright © 2010 John Wiley & Sons, Ltd.

     

Breeding site selection by olfactory cues in the threatened northern spectacled salamander Salamandrina perspicillata (Savi, 1821)

• 1. The conservation of small aquatic habitats is fundamental to preserving diversity in Mediterranean freshwater ecosystems. Amphibians are particularly endangered, as their chemical world, represented by both abiotic and biotic scent trails, is highly susceptible to environmental changes.
• 2. Breeding site fidelity in the northern spectacled salamander, Salamandrina perspicillata, an Italian endemic vertebrate, was investigated with respect to the ability of this species to locate its own home water rather than that from other places. The choice of aquatic habitat for spawning was investigated in dark conditions by comparing different types of experimental water (home breeding water vs. breeding water of allopatric populations vs. mineral water vs. distilled water). Fifty‐eight reproductive females were collected at four breeding sites in the Lepini Mountains (Latium, central Italy). The number of eggs spawned by each specimen in the different types of experimental water was counted.
• 3. The very large majority of the eggs were found in the home breeding water. When the eggs counted in the other types of water were compared, no differences were found.
• 4. These findings revealed that in the northern spectacled salamander the choice of spawning site was affected by the scent trail of its own aquatic habitat. This new information has improved knowledge of the auto‐ecology of S. perspicillata, thus contributing to strategies for its conservation.

Copyright © 2007 John Wiley & Sons, Ltd.     

Invasive tilapia juveniles are associated with degraded river habitats

• 1. Invasions are a main concern for conservationists. Identification of causes that raise or promote an invader's success is one of the first steps for preventing and/or fighting against invasions.
• 2. In the Brazilian River Paraiba do Sul, juveniles of invasive tilapia Oreochromis niloticus were detected associated with degraded habitats (mainly pollution from various sources). The relative abundance of juveniles of the competitor native species pearl cichlid Geophagus brasiliensis, morphologically and ecologically very similar, was negatively associated with habitat degradation.
• 3. A species‐specific molecular marker was employed to permit unambiguous identification of these small juveniles (2–3 cm long), which represent the most vulnerable life stage of both species.
• 4. It is suggested that adaptation to degraded habitats is one of the characteristics of invasive species, and consequently habitat conservation and restoration may help to prevent fish invasions.

Copyright © 2008 John Wiley & Sons, Ltd.     

Distribution and reproduction of Procambarus clarkii in relation to water management,salinity and habitat type in the Camargue

相似文献   

Stable isotope ratios of egg albumen of three waterbird species nesting in the Colorado River Delta indicate differences in foraging ground and isotopic niche breadth

相似文献   

Southern right whale (Eubalaena australis), seasonal abundance and distribution at Head of Bight,South Australia

1. Seasonal trends in the distribution and relative abundance of southern right whales (SRWs) Eubalaena australis, were assessed in Australia's largest calving aggregation ground at the Head of the Great Australian Bight, in the Commonwealth Marine Reserve, South Australia. Annual cliff‐based surveys were undertaken between June and October from 1992 to 2016.
2. SRWs were primarily distributed in a 15 km by 2 km area within the 10 m depth contour (with 95% of whale sightings made within a 10 km² area). The distribution of SRWs at Head of Bight varied within an individual season but was consistent among the years. The composition of SRW sightings was 70% female–calf pairs and 30% unaccompanied whales.
3. Peak abundance occurred between mid‐July and end‐August for female–calf pairs and unaccompanied whales (juveniles or adults not accompanied by a calf), earlier than previously reported. A mean of 16% (range 8–28%, SD = 6.5, 95% CI = 0.15) of calving females were present at the site in mid‐June and a mean of 37% (range 13–61%, SD = 15.8, 95% CI = 0.37) remained at the site at the end of September.
4. Based on nearest‐neighbour distances of 150 m, the area occupied by 95% of SRWs at Head of Bight could reach carrying capacity at 68 female and calf pairs. Results suggest that the primary aggregation area at Head of Bight may have reached saturation capacity and that habitat expansion can be expected as the population increases.
5. This study provides information on SRW seasonal trends in distribution and abundance, timing of arrival and departure from the site and peak abundance periods relevant to application to conservation and marine park management.
6. As management requirements increase with a growing population, there is a need to complete an Australia‐wide assessment of SRW connectivity and habitat expansion.

     

Smalltooth sawfish (Pristis pectinata Latham, 1794) in the Casamance River,Senegal: A historical perspective

1. A study of euryhaline elasmobranchs was conducted in the Casamance River, southern Senegal, between June 1974 and October 1975.
2. Data were collected from 159 sawfish, comprising 158 smalltooth sawfish (Pristis pectinata Latham, 1794) and one largetooth sawfish (Pristis pristis Linnaeus, 1758).
3. The mean total rostral tooth count for P. pectinata was 46 (range 41–53), significantly lower than the total tooth counts for the western Atlantic population. No sexual dimorphism in rostral tooth counts was apparent, in contrast to findings from the western Atlantic.
4. The total rostral length averaged 22.9% of the total length.
5. One hundred and forty‐four individuals were caught within the river system itself, all of them were juveniles. Fifteen adults, including the single largetooth sawfish documented during the study, were caught at the river mouth or at sea.
6. Six sawfish, caught between May and July, bore rostral sheaths, indicating that they had recently been born.
7. Although the Casamance and Gambia rivers are only 120 km apart, the findings from this study combined with published data collected from the Gambia River during the same period suggest the partitioning of juvenile habitats by the two sawfish species present in the region, to the level of different river systems. Both species are likely to have used the same coastal habitats as adults.
8. The Casamance River was clearly an important habitat for smalltooth sawfish some 40 years ago, but it is unknown whether the species persists there. Intensive artisanal fisheries for sharks and rays in the region poses a significant threat to any remaining sawfishes, and a challenge for elasmobranch fisheries management.

     

Reproductive dynamics and nursery habitat preferences of two commercially important Indo-Pacific red snappers <Emphasis Type="Italic">Lutjanus erythropterus</Emphasis> and <Emphasis Type="Italic">L. malabaricus</Emphasis>

Red snappers were examined for reproductive biology and age-0 habitat preferences. Spawning in red snappers occurred throughout the year in northern Australia and eastern Indonesia; at least 10–30% of females and 40–80% of males were in ripe or spawning condition in most months. Northern Australian populations showed a spawning peak from July to December (L. erythropterus) and September to March (L. malabaricus). Eastern Indonesian L. malabaricus had a less defined pattern with two peaks: January–March and October. Size at first maturity was 240 mm for males and 250–300 mm for females. L ₅₀ estimates were similar between species in northern Australia: 270–280 mm (males) and 350–370 mm (females). Maximum batch fecundity was 676,100 oocytes for L. erythropterus and 997,000 oocytes for L. malabaricus. Higher mean abundances of age-0 L. erythropterus were found in silty and coarse sand/rubble estuarine habitats of northern Australia (456 ± 119 fish/km²) compared with sandy coastal habitats (5 ± 3 fish/km²). Most age-0 snapper caught at Sape (eastern Indonesia) were L. malabaricus (91%) with mean abundances of 312 ± 14 fish/km². The similarities in the reproductive characteristics of red snappers suggest that successful management approaches adopted in northern Australia should be considered in eastern Indonesia.     

Improved detection sensitivity using an optimal eDNA preservation and extraction workflow and its application to threatened sawfishes

1. Pressures on coastal ecosystems are increasing and aquatic species that are restricted to these habitats are facing the threat of extinction. However, the true extent of many threatened and rare aquatic species, especially elasmobranchs, remains unclear due to high levels of data deficiency and poor efficacy of traditional survey methods. Sawfishes (Pristidae), a family of shark-like rays, are among the most threatened and rare elasmobranch species and are difficult to detect in turbid, coastal habitats. Reliable cost-effective tools to detect these species are urgently needed to increase their conservation potential.
2. Characterization of environmental DNA (eDNA) extracted from water samples has garnered significant appeal for detection of rare and threatened species. To assist conservation and monitoring efforts for sawfishes using eDNA, species-specific TaqMan quantitative polymerase chain reaction assays were developed and validated to detect 1.25–5 copies of a 12S rRNA gene fragment. Filter samples were collected in Northern Territory, Australia to assess the utility of the developed eDNA assays and compare the efficacy of preservation and extraction workflows for detecting rare species.
3. Dwarf sawfish (Pristis clavata) were detected in three of 20 sites, and there was a significant effect of preservation and extraction workflow on total eDNA yield and subsequent detection success. Longmire's preserved samples extracted using glycogen-aided precipitation yielded a significantly higher concentration of total eDNA (n = 60; β = 1.27, t(95) = 8.172, P < 0.0001) and yielded positive P. clavata eDNA detections compared to ethanol preserved samples extracted using QIAGEN DNeasy kit, which did not yield any positive detections.
4. The optimized eDNA assays were developed to support monitoring efforts for endangered sawfishes. Importantly, this study demonstrates that choice of preservation and extraction workflow requires careful consideration, especially when detection of rare or threatened species can have important management and conservation outcomes.

     

Bioindicator role of aquatic Ranunculus in Mediterranean freshwater habitats

相似文献   

Aquatic Coleoptera and Hemiptera assemblages in three coastal lagoons of the NW Iberian Peninsula: assessment of conservation value and response to environmental factors

• 1. The objectives of the present study were to describe and analyse the composition and structure of aquatic Coleoptera and Hemiptera assemblages in three coastal lagoons of north‐western Spain during a one year cycle, in order to evaluate their relative adequacy to provide information about the conservation value of lagoonal habitats and sites. The lagoons are designated as Special Areas of Conservation (SAC) under the European Union Habitats Directive and two of them are also protected by the Ramsar Agreement. Several abiotic variables, including salinity, were recorded at the time of sampling.
• 2. In total, 67 species (52 Coleoptera and 15 Hemiptera) and 6568 adult individuals (2664 Coleoptera and 3904 Hemiptera) were collected. In all pair‐wise comparisons Kendall's coefficients of concordance between lagoons were higher for Hemiptera than for Coleoptera, indicating that Hemiptera assemblages were more similar across sites.
• 3. Most species recorded had a wide Palearctic distribution and only three species of water beetles could be considered endemic to Iberia: Hydroporus vagepictus, Hydroporus vespertinus and Hydrochus angusi. Similarly, the species collected had a widespread distribution in the Iberian Peninsula as the only species considered to be rare taxa at this scale were Hydrochus angusi and Cymbiodyta marginella among the Coleoptera and Sigara scotti and Notonecta glauca glauca among the Hemiptera.
• 4. The results do not support the idea of distinct aquatic insect assemblages for coastal lagoons in the Iberian Peninsula. Comparisons of the numbers of interior (non‐coastal) and coastal provinces of the Iberian Peninsula where the species had been recorded showed they had been recorded in a larger proportion of interior provinces.
• 5. Salinity seemed to reduce species richness in both groups while the results of a canonical correspondence analysis (CCA) showed that the majority of species responded negatively to salinity.
• 6. This study suggests that species richness and rarity of aquatic insect assemblages may underestimate the conservation value of lagoonal habitats because their net contribution to catchment biodiversity is likely to be low.

Copyright © 2007 John Wiley & Sons, Ltd.     

Importance of various marine coastal habitats during the life cycle of Spratelloides delicatulus in Con Dao,the oldest MPA in Vietnam

• 1. Marine protected areas (MPAs) are set up to conserve biodiversity, but their design is not always based on strictly scientific considerations. Ideally, an MPA should protect all key habitats necessary for a marine species to complete its life cycle. The identification of these key habitats is complex, especially during the early life of marine fishes.
• 2. A widely distributed tropical and important low trophic‐level fish species, Spratelloides delicatulus (Clupeidae), was used to evaluate the significance of various coastal habitats for its larvae and juveniles in the Con Dao Archipelago MPA in Vietnam. Early stages (larvae and juveniles) were sampled monthly over one year (June 2016 to May 2017) using light traps in three main habitats (seagrass beds, coral reefs and harbour). The species was identified using morphometry and DNA barcoding. Age and growth variables were estimated using otolith daily growth increments.
• 3. A total of 3,581 fish were caught. The species was not found in captures between January and February, directly linked to the decrease in seawater temperature and was most abundant from April to June. For a subsample of 248 fish (7–38 mm standard length), ages ranged from 7 to 108 days.
• 4. Captures and back‐calculated birthdates using otolith daily increments showed that S. delicatulus spawns during the period of high seawater temperature, from March to October. The species colonizes all three habitats during the early stages (0–26 days old), with growth rate lowest on the seagrass beds. Nevertheless, the species occupies seagrass beds exclusively during the older stages.
• 5. The conservation of seagrass beds in the Con Dao archipelago is essential for protection of juvenile stages of this species but this habitat is presently not included in the MPA patches. Establishment of a continuum of protected areas linking habitats, rather than the existing patches is needed to conserve the complete life cycle of this species in the Con Dao MPA.

     

Seasonally tracking vertical and horizontal distribution of unionid mussels (Pronodularia japanensis): implications for agricultural drainage management

• 1. The vertical and horizontal distribution of unionoid mussels (Pronodularia japanensis) were examined in spring, late summer and winter for different size classes, including juveniles (<20 mm) and large adults (>50 mm), in an agricultural drainage channel in Central Japan.
• 2. A large number of small‐sized juveniles were found at the surface (0–3 cm depth) in spring, whereas approximately half of the adults remained in the deep layer (3–8 cm depth). Most individuals were found in the surface layer irrespective of size classes in summer, and approximately 70% of all individuals descended to the deep layer in winter.
• 3. Horizontal distribution did not substantially change across seasons and high density patches were consistently found in the areas where substrate appeared to be stable or hydraulically sheltered. Spatial distribution of small juveniles was relatively well predicted by the abundance of adults.
• 4. The size–frequency distribution was multi‐modal in three seasons and estimated numbers of newly recruited juveniles were highly variable in recent years, suggesting that juveniles were rarely found owing to irregular reproduction and/or recruitment not the overlooked habitat preferred by small‐sized juveniles.
• 5. As P. japanensis is characterized by the behaviour of burrowing down to a depth of ～10 cm, maintaining the processes of sediment deposition appears to be one of the critical criteria for the conservation of mussel habitats in agricultural drainage channel systems, which are commonly lined with smooth concrete materials. Copyright © 2010 John Wiley & Sons, Ltd.

     

Water levels in a highland lake control the quantity and quality of spawning habitat for a littoral‐spawning galaxiid fish

1. In comparison with other habitats, the littoral zone can be disproportionately important to lentic fishes, especially for species that rely on it for reproduction. Impoundment of lentic waters can alter hydrological regimes, littoral inundation patterns and hydrodynamic processes, which can affect the quantity and quality of littoral habitats.
2. This study examined the effects of water‐level fluctuations on the quantity and quality of rocky littoral spawning habitat for the threatened Galaxias auratus in the Crescent–Sorell lake system, Tasmania (Australia) using GIS analyses, sediment measurements and observations of the composition and condition of littoral substrates under varying hydrological conditions.
3. The extent of littoral rocky substrate was found to be limited in Lake Crescent (<1.3% of the lake's bed). The relationship between water levels and G. auratus spawning habitat (littoral rocky substrates at depths of 0.2–0.6 m) was non‐linear with spawning habitat quantity and quality declining markedly at water levels <802.20 m Australian Height Datum (AHD). Hydrological impacts of global climate change on the Crescent–Sorell lake system are likely to increase the occurrence of water levels below this threshold in Lake Crescent in the future, thereby limiting the ability of G. auratus to sustain its population in this lake.
4. The structure of littoral areas of rocky substrate in Lake Crescent and Lake Sorell, and influential processes acting on these areas under varying hydrological conditions, were conceptualized to assist transferability of this knowledge to other lentic waters and species with similar habitat requirements.
5. Global climate change is predicted to alter lacustrine hydrological regimes and shoreline environments. This is likely to have significant ramifications for fishes that use littoral habitats during their life cycles, especially crucial reproductive phases. We believe the influence of alterations to hydrological regimes on the availability of these habitats to lacustrine fishes requires further investigation globally.

Copyright © 2016 John Wiley & Sons, Ltd.     

Environmental flow releases trigger spawning migrations by Australian grayling Prototroctes maraena,a threatened,diadromous fish

相似文献