Conservation, Volume 2, Issue 3 (September 2022) – 9 articles

Invasive predators pose a critical threat to native taxa. Body size plays an important role in mediating the interactions of predator and prey. For piscivorous fishes, increased predator body size can be accompanied by the selection of increasingly larger prey or may reflect a mix of small and large prey. Knowledge of such interactions helps determine how predation affects population vital rates. Here, we assessed the predatory effects of invasive Brown Trout (Salmo trutta) on populations of native Rio Grande Sucker (Catostomus plebeius) and Rio Grande Chub (Gila pandora) in streams of the Jemez River watershed (New Mexico, USA). Trout diets were sampled every two weeks during the 2020 growing season. Predator and prey body lengths were measured to examine relationships to better understand patterns of piscivory and quantify the threat Brown Trout pose to populations of Rio Grande Chub and Rio Grande Sucker. Across all streams and sampling dates, 7% of Brown Trout diets contained fish. Predator–prey length relationships reflected a ‘wedge’ pattern, indicating that Brown Trout consumed an increasing range of prey body sizes as they grew larger. Rio Grande Sucker and Rio Grande Chub comprised 46% of consumed fishes. The findings demonstrated that Rio Grande Sucker and Rio Grande Chub experience constant predation over the growing season by Brown Trout. Moreover, our study provides evidence that these invasive predators pose a threat to the viability of Rio Grande Chub and Rio Grande Sucker populations. Conservation efforts to protect these chub and sucker populations must account for and directly address predation by invasive Brown Trout. Full article

This article reviews investigations in which Canna indica was utilized in constructed wetlands (CW) for wastewater treatment of a variety types. It is strongly urged that ornamental flowering plants be used in CWs as monoculture or mixed species to improve the appearance of CWs whilst still treating wastewater. Plants play important roles in CWs by giving the conditions for physical filtration of wastewater, a large specific surface area for microbial growth, and a source of carbohydrates for bacteria. They absorb nutrients and integrate them into plant tissues. They release oxygen into the substrate, establishing a zone in which aerobic microorganisms can thrive and chemical oxidation can occur. They also provide wildlife habitat and make wastewater treatment system more visually attractive. The selection of plant species for CW is an important aspect during the CW design process. Canna indica’s effectiveness in CWs has shown encouraging results for eliminating contaminants from wastewater. There is still a scarcity of information on the mechanisms involved in removal of specific contaminants such as pharmaceuticals, personal care products, hormones, pesticides and steroids and their potential toxicity to the plants. Therefore, this paper reviews some published information about the performance of Canna indica in wastewater treatment, as well as potential areas for future research. Full article

With continuous developments in the integration of culture and tourism, adaptive reuse has highlighted the vitality of historic conservation areas while simultaneously causing great challenges to urban life, local economy, and cultural sustainability. Current studies focus on the adaptive reuse of historic buildings, with little focus on historic conservation areas. To expand this understanding further, this study investigated and analyzed the challenges faced by Chengdu historic conservation areas in the context of adapting to the tourism environment, from multiple perspectives, and proposed corresponding protection and development strategies. The results of the study obtained using field investigation and semi-structured interviews contribute to the literature on the adaptive reuse of historic conservation areas; they deepen our understanding of the identified factors and provide in-depth knowledge. These findings provide a reference for future practices and promote the sustainable development of historic conservation areas for improved conservation and economic returns. Full article

Food safety is currently a serious concern due to the health risks associated with food intake, particularly due to heavy metal contamination. Therefore, the present study was conducted to investigate the heavy metals concentration in water and fishes collected from Hakaluki haor, Bangladesh. Three important fish species, Labeo rohita, Cirrhinus cirrhosis, and Labeo calbasu, together with water samples, were analyzed for heavy metals (Pb, Cr, and Cd), respectively. Considering four seasons, namely the monsoon, post-monsoon, winter, and pre-monsoon, a total of 72 fish samples were collected from three fishing stations from June 2017 to May 2018. The results showed that the total mean concentration of metals in water (mg L⁻¹) was found to be in the order of Pb (0.125 ± 0.058) > Cr (0.026 ± 0.012) > Cd (0.001 ± 0.0002) within the maximum permissible limits set by the EU and WHO, except for Pb concentrations. Similarly, the total mean concentrations of Pb in fish (µg g⁻¹) were found in order of L. rohita (0.388 ± 0.291) > Cirrhinus cirrhosus (0.334 ± 0.236) > L. calbasu (0.251 ± 0.117) greater than the maximum permissible limits (0.3 µg g⁻¹) set by FIQC, except for L. calbasu. However, the mean concentrations of Cr and Cd in fish were found to be below the maximum permissible limits of FAO and FIQC, respectively. The quantity of heavy metal contamination in this haor indicates that the situation is worrying for the region’s biota and residents. However, to protect public health and reduce environmental risk, the appropriate authorities should oversee and monitor it with strong hands. Full article

The monoculture of avocado (Persea americana) has triggered the loss of large forested areas in central Mexico, including the habitat of threatened species. This study assessed the potential habitat loss of ten threatened pollinator species due to the expansion of avocado monoculture in Mexico. First, we modeled the distribution of avocado and pollinators. Then, we overlapped their suitable areas at a national level and within the Trans-Mexican Volcanic Belt (TMVB). We also identified the areas with more affected pollinators and coinciding with protected areas. As a result, 78% of the suitable areas for avocado coincided with the distribution of at least one pollinator. Although only two pollinators lost more than one-fifth of their distribution at a national level, the habitat loss increased to 41.6% on average, considering their distribution within the TMVB. The most affected pollinators were Bombus brachycephalus, B diligens, Danaus plexippus, and Tilmatura dupontii, losing more than 48% of their distribution within this ecoregion. The areas with a greater number of affected species pollinators were found in the states of Michoacán, Mexico, and Morelos, where most of the area is currently unprotected. Our results suggest that the expansion of the avocado monoculture will negatively affect the habitat of threatened pollinators in Mexico. Full article

Beach-nesting birds (plovers; Aves; Charadridae) are impacted by many natural and human-induced threats (e.g., people trampling, dogs, and natural predators). In this regard, the use of anti-predator cages on their nests is effective in order to mitigate some of these pressures (i.e., predation). To evaluate the efficacy of anti-predator cages and the causes of nest failure in a breeding site of two species (Charadrius alexandrinus and C. dubius), we carried out a control-experimental design, comparing false nests (n = 69) in cages (experiment; n = 30) with false nests without cages (control; n = 39). We carried out the study in three seasonal periods (May, June, and July), controlling predations after three periods (three, six, and nine days) since positioning, recording the frequency of eggs still present and evidencing any predation event. The percentage of residual eggs was significantly higher in experimental nests when compared to control nests in all recording periods. Considering 59 predation events on false nests, the most important predators were: in experimental nests (n = 21) the fox, Vulpes vulpes (47.6%), and in control nests (n = 38), the hooded crow, Corvus cornix (50%). Our data suggest that the use of anti-predator cages significantly limits predation on eggs and therefore is likely to increase the hatching success in these ground-nesting birds independently in the seasonal period. However, also in the presence of a cage, the fox is a relevant egg predator. Full article

Climate change has caused substantial losses, especially to smallholder farmers whose main source of livelihood is derived from agriculture. Climate change impacts can be reduced by enhancing coping and adaptation strategies. This study explores the coping and adaptation strategies of smallholder farming communities in the Limpopo Province, South Africa. As part of the assessment and analysis of drought, multiple sources of data were consulted, including 200 households’ socio-economic information, focus group discussions, and interviews. Extreme drought events are increasing, impacting negatively on smallholder farmers’ livelihoods. Adaptations to changing weather patterns were observed in smallholder farmers through planting early-maturing plants and drought-tolerant crops, altering planting dates, crop diversification, and irrigating in addition to non-farming activities. There is a need to enhance these context-based adaptation strategies to reduce risks and vulnerability and increase household resilience. Several socioeconomic developments and significant ecological deterioration appear to limit opportunities for long-term adaptation to drought. Full article

Variation in salinity is one of the major environmental factors influencing the species diversity of fish in an estuary. Therefore, evaluating the relationship between salinity and species diversity is important. In this study, fish diversity was assessed by fish sampling and visiting local fish markets from February to November 2021. Mean salinity was 10.59 psu (Practical Salinity Unit) and 0.46 psu during the dry and wet seasons, respectively. Harpadon nehereus, Odontamblyopus rubicundus and Pseudapocryptes elongatus species were found as polyhaline (0.06~18.1 psu) species. Anguilla japonica and Arius gagora were abundant in brackish water conditions (0.35~14.2 psu). However, Acanthopagrus latus and Setipinna phasa were found in freshwater conditions (0.06~0.11 psu). The suitability index indicates that commercially important fish species such as Liza parsia, Macrobrachium rosenbergii, Mugil cephalus, Penaeus monodon and Scylla serrata can be used for mariculture during the dry season, and Acanthopagrus latus, Pethia canius and Setipinna phasa during the wet season. Overall, these findings suggest that salinity, water temperature, and chlorophyll-a had a significant (p < 0.05) effect on the fish distribution and assemblage composition in the study area. This finding will be helpful in developing policies for the conservation and management of the aquatic resources in the coastal zone to enrich the blue economy. Full article

Identifying spatial and temporal patterns of human–carnivore encounters is crucial for predicting conflict hotspots. However, the degree of overlap between human and carnivore movements is likely to differ between stable environments and seasonally changing landscapes. We aimed to clarify key drivers of spatial and temporal overlap of humans and carnivores in a seasonally changing landscape using the case of human–fishing cat encounters in an inland wetland in north-eastern Bangladesh. To obtain encounter information, interview surveys were conducted with 210 respondents in 21 villages in 2020. Monthly rainfall and waterbody size were negatively correlated with the numbers of encounters in the wetland area, while there was no apparent temporal pattern in encounters reported in adjacent villages. Temporal patterns of encounters may be partially explained by human presence (in turn associated with local livelihoods). Except for fishing, intense livelihood activities take place in wetland areas mainly during the dry season. On the other hand, areas peripheral to the wetlands are used for various livelihood activities throughout the year. In a seasonally changing landscape, understanding people’s movements could help elucidate spatiotemporal patterns of human–fishing cat encounters at a micro-scale. Full article