This study aimed to develop original laboratory culture and sediment toxicity testing protocols for the freshwater gastropod Bellamya aeruginosa (Reeve), a new potential species for sediment toxicity testing. B. aeruginosa was successfully cultured with an effective culture system under proposed laboratory conditions. Optimal ad libitum feeding levels for larvae, juveniles, and adults were 2.0, 6.0, and 16.0 mg fish food/(snail·day), respectively. Mean survival rates of juveniles were higher than 90%. The snails could be sexed at 9 weeks of age, and their generation time is approximately 4 months. Reproduction continued all year around; the mean fecundity was 0.55 newborn/(female·day). The utility of this species for bioassays was evaluated in both 10-day and 28-day case studies with artificial sediments. The 10-day LC 50 of Cu for larvae was 480 μg/g dry weight (dw), and the lowest observed effects concentration of Cu for survival and growth of larvae was 195 μg/g dw. Survival and growth are reliable indicators of acute toxicity. Larvae accumulated more Cu than adults. B. aeruginosa exhibited a higher sensitivity to Cu exposure than standard test species (Hyalella azteca and Chironomus tentans). The 28-day test of sediment toxicity with adults showed that fecundity was a robust endpoint indicator of reproductive toxicity, and the biochemical endpoints of superoxide dismutase, catalase, and glutathione could be used as sensitive biomarkers for Cu-induced oxidative damage. B. aeruginosa can be therefore recommended as a candidate for the standardization of the freshwater sediment toxicity test protocol.
Context Tourism is becoming one of the largest and fastest growing industries in many countries. Increasing tourism exerts serious impacts on the habitats of wildlife in nature reserves. Aims To ascertain how tourism affects the habitat of the Chinese giant salamander (Andrias davidianus), especially water quality and population size. Method An experiment was conducted to investigate the influences of different tourism disturbance intensities on the habitat quality and population size of the Chinese giant salamander in the Hunan Zhangjiajie Chinese Giant Salamander National Nature Reserve. Habitat characteristics, water physicochemical properties and microbial abundance were analysed, and population size estimated. Key results The results showed that high levels of tourism disturbance (>100 000 visitors per year) had negative effects on habitat quality. These effects included increased noise and abundance of aquatic microbes, increased concentration of total nitrogen (TN) and total phosphorus (TP) and a reduction of dissolved oxygen (DO) in water. The abundance of Escherichia coli could be regarded as an indicator of tourism disturbance on Chinese giant salamander. Conclusions It is concluded that: (1) the habitats were much noisier with increasing numbers of tourists, which might directly reduce the population size; (2) tourism indirectly disturbs the salamander population by increasing TN and TP, and reducing DO in the water; and (3) tourism might take in pathogenic microbes to the water habitats, which could cause disease for the salamander population. Implications Although tourism development might reduce local poverty, such efforts must consider the deterioration of habitats for wildlife, especially for this endangered animal species. Moreover, the intensity of tourism disturbance needs be reduced (by controlling the number of tourists) to achieve the coordinated development of tourism and wild animal protection.
Simple SummaryBehavioral research on wild Chinese giant salamanders (Andrias davidianus) is in its infancy because A. davidianus inhabit underground river dens that are difficult to access. In order to ascertain the types of reproductive behavior exhibited by A. davidianus, this paper monitored their reproductive activity using a digital monitoring system in a simulated natural habitat. The survey uncovered reproductive behavior such as sand-pushing, showering, courtship, oviposition, and parental care. We also recorded the parental care time allocation for the first time. This study provides a scientific basis for the method optimization for the ecological reproduction of A. davidianus and the conservation of its wild population. This study also demonstrates that a digital monitoring system is an effective research method for investigating the behavior of Cryptobranchidae and other cave animals.AbstractKnowledge of natural animal behavior is essential for enhancing the protection and artificial breeding of animals. At present, the behavior of the Chinese giant salamander (Andrias davidianus) is studied through interviews with local people or occasional observations under artificial conditions, leading to a lack of systematic records. Thus, most reports are descriptive and lack quantitative analyses. To ascertain the types of reproductive activities and their corresponding time allocations, this study observed the reproductive behavior of A. davidianus using a digital monitoring system for the first time. The results showed that sand-pushing behavior is mainly carried out by the limbs, tail, head, and body of den-dominant males. Showering behaviors included rinsing the trunk, head, and tail. Courtship was composed of a series of behaviors, including standing side-by-side, belly colliding, mounting, mouth-to-mouth posturing, chasing, inviting, cohabitating, and rolling over. After chasing and interlocking with the male, the female discharged her eggs. The oviposition process began at either 02:04 or 04:09, and lasted either 66 or 182 min. Parental care included tail fanning, agitation, shaking, and eating dead and unfertilized eggs, and the durations of these behaviors accounted for 31.74 ± 4.35%, 17.42 ± 4.00%, 3.85 ± 1.18%, and 1.19 ± 0.69% of the entire incubation period, respectively. This paper reveals the characteristics of the reproductive behavior of A. davidianus and provides a scientific basis for the management of its ecological breeding and the conservation of its wild populations.
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