The excessive enrichment of trace elements in migratory and breeding red-crowned cranes (Grus japonensis) in China

Diet Drives Gut Bacterial Diversity of Wild and Semi-Captive Common Cranes (Grus grus)

The gut microbiota of wild animals can regulate host physical health to adapt to the environment. High-throughput sequencing from fecal samples was used to analyze the gut microbiota communities in common cranes (Grus grus) without harming them. Herein, we compared the fecal microbiome of fifteen G. grus in Tianjin Tuanbo Bird Natural Reserve (wild group) and six G. grus sampled from Beijing Wildlife Park (semi-captive group) in China, using 16S amplicon sequencing and bioinformatic analysis. The results showed that microbiota diversity and composition varied in different groups, suggesting that the gut microbiota was interactively influenced by diet and the environment. A total of 38 phyla and 776 genera were analyzed in this study. The dominant phyla of the G. grus were Firmicutes and Proteobacteria. Meanwhile, the microbiota richness of the semi-captive group was higher than the wild group. Data on beta diversity highlighted significant differences based on different dietary compositions. Zea mays, Glycine max, and Phragmites australia showed a significant correlation with intestinal bacteria of G. grus. This study provides a comprehensive analysis of diet and microbiomes in semi-captive and wild G. grus living in different environments, thus helping us to evaluate the influence on animal microbiomes and improve conservation efforts for this species.

Spatial distribution and sources of heavy metals in the sediment and soils of the Yancheng coastal ecosystem and associated ecological risks

Studies of heavy metal pollution are essential for the protection of coastal environments. In this study, positive matrix factorization (PMF) and a GeoDetector model were used to evaluate the sources of heavy metal contamination and associated ecological risks along the Yancheng Coastal Wetland. The distribution of heavy metals was shown to be greatly affected by clay content, except for Cr in shoal. Components from 6.5 to 9φ have the strongest ability to absorb heavy metals, where the effects of Cd and Zn sequestration in the wetlands were most apparent. The abilities of various wetland environments to sequester heavy metals were shown to be Spartina alterniflora wetland > woodland > Phragmites australis wetland > aquaculture pond > shoal > paddy > meadow > dry land. The sources of the heavy metals included parent soil material (59%), agriculture (15%), and industrial pollutants (26%). According to the single-factor pollution index, there was no evidence of pollution except Cr and Pb. In general, the heavy metal pollution was insignificant. The order of pollution loading index was shoal > paddy field > dry land > Spartina Alterniflora wetland > aquaculture ponds > woodland > meadow > Phragmites australis wetland. The ecological harm of heavy metal exposure was slight except for Cd and Hg, where vehicle emissions appeared to be the main cause of heavy metal pollution.

Winners and losers of land use change: A systematic review of interactions between the world’s crane species ( Gruidae ) and the agricultural sector

While agricultural intensification and expansion are major factors driving loss and degradation of natural habitat and species decline, some wildlife species also benefit from agriculturally managed habitats. This may lead to high population densities with impacts on both human livelihoods and wildlife conservation. Cranes are a group of 15 species worldwide, affected both negatively and positively by agricultural practices. While eleven species face critical population declines, numbers of common cranes (Grus grus) and sandhill cranes (Grus canadensis) have increased drastically in the last 40 years. Their increase is associated with higher incidences of crane foraging on agricultural crops, causing financial losses to farmers. Our aim was to synthesize scientific knowledge on the bilateral effects of land use change and crane populations. We conducted a systematic literature review of peer‐reviewed publications on agriculture‐crane interactions (n = 135) and on the importance of agricultural crops in the diet of cranes (n = 81). Agricultural crops constitute a considerable part of the diet of all crane species (average of 37%, most frequently maize (Zea mays L.) and wheat (Triticum aestivum L.)). Crop damage was identified in only 10% of all agriculture‐crane interactions, although one‐third of interactions included cranes foraging on cropland. Using a conceptual framework analysis, we identified two major pathways in agriculture‐crane interactions: (1) habitat loss with negative effects on crane species dependent on specific habitats, and (2) expanding agricultural habitats with superabundant food availability beneficial for opportunistic crane species. The degree to which crane species can adapt to agricultural land use changes may be an important factor explaining their population response. We conclude that multi‐objective management needs to combine land sparing and land sharing strategies at landscape scale. To support viable crane populations while guaranteeing sustainable agricultural production, it is necessary to include the perspectives of diverse stakeholders and streamline conservation initiatives and agricultural policy accordingly.

Assessment of Pb and Cd contaminations in the urban waterway sediments of the Nen River (Qiqihar section), Northeastern China, and transfer along the food chain

The increasing anthropogenic inputs of Pb and Cd into China's Nen River (Qiqihar section) owing to rapid urbanization in the past 50 years may pose ecological risks to the river's aquatic system. To confirm this hypothesis, we determined the Pb and Cd concentrations in the sediments of the Nen River flowing across Qiqihar City by comparing the control group (samplings in the Nen River branch bypassing the city) and bioaccumulation along the food chain. We found significantly higher Pb concentrations in the sediments than in the control group (39.21 mg kg^-1 dry weight [dw] vs. 22.44 mg kg^-1 dw; p < 0.05). However, the difference between the Cd contents of the two groups was nonsignificant (0.33 mg kg^-1 dw vs. 0.30 mg kg^-1 dw) (p = 0.07). Accumulated Pb and Cd in the sediments pose a medium risk to the system of Nen River according to the result of risk assessment code analysis. The increased Pb and Cd levels along the food chain had adverse health effects in the species at the top level of the food chain. For example, the feathers of Corvus frugilegus and Sterna hirundo contained 0.28-2.25 mg kg^-1 dw of Cd. These values are considered potentially toxic to common avian species. The bone Pb level of C. frugilegus ranged from 4.82 to 7.41 mg kg^-1 dw within the increasing Pb range (2-15 mg kg^-1 dw) of common water birds. The inputs of Pb and Cd into the local environment should be reduced for the preservation of aquatic system health.