Functional Feeding Guilds Research Articles

Heavy metal bioaccumulation in the macroinvertebrate functional feeding guilds of an impaired stream in South-West Nigeria

ABSTRACT Anthropogenic impacts and the accumulation of heavy metals in water bodies have increased significantly as a result of increased urbanisation, endangering both aquatic biota and human health. The pace of urbanisation and its attendant freshwater ecosystem pollution in Nigeria is so fast that there are concerns for the nation’s freshwater biota. To this end, six heavy metals were investigated in the water column, sediment, and tissues of macroinvertebrate functional feeding guilds (FFGs) of a Nigerian stream. Three heavy metals that are non-essential (As, Cd, and Pb) exceeded their WHO permissible limits for surface fresh waters. According to the geo-accumulation index (Igeo) and contamination factor (CF) used to assess heavy metal pollution, there was a high level of Cd contamination among all heavy metals found in the sediment. These heavy metals were all biomagnified (>1), especially among the predators. The study concluded that Opa Stream was moderately impacted based on the concentrations of heavy metals in the stream’s water column, sediment, and macroinvertebrate tissues. Future research works can consider the remediation of heavy metals that are non-essential in freshwater systems to ensure the sustainability of freshwater biodiversity and human health.

Assessment of the floodplain fishery of Tonle Sap Lake in Cambodia

AbstractAcross the globe, fish stocks have been in decline due to industrialization of fisheries resources, overfishing, pollution, and climate change, thereby warranting more fisheries assessments. The floodplain fishery of Tonle Sap Lake near the Kampong Khleang stilted community in the Chamkar Youn village in Cambodia was evaluated by: (1) characterizing fish assemblage structure and function, (2) highlighting temporal differences in fish assemblage, and (3) assessing potential indicators of fishing‐down‐the‐food‐web by the fishery. Fish trap data from the wet season were used to characterize fish abundance, diversity, species richness, and functional feeding guilds from fish catches in 2014 and 2019. Fish abundance declined 62% and species richness declined between 2014 and 2019. Smaller‐bodied, lower‐trophic level fishes dominated the catch. Our limited findings add insight into the status of a globally important fishery and highlight the need for more local collaborative fishery assessments.

Fatty-acid based assessment of benthic food-web responses to multiple stressors in a large river system

Rivers are often exposed to multiple stressors, such as nutrients and contaminants, whose impacts on the river food webs may not be distinguished by sole assessment of biological community structures. We examined the benthic algal assemblages and the fatty acids (FA) of benthic macroinvertebrates in the lower Athabasca River in Canada, aiming to assess the changes in algal support and nutritional quality of the benthic food web in response to cumulative exposure to natural bitumen, municipal sewage discharge (hereafter, “sewage”), and oil sands mining (“mining”). Data show that the decline in water quality (increases in nutrient concentrations and total suspended solids) was associated with decreases in benthic diatom abundance, and was driven mainly by sewage-induced nutrient enrichment. Responses in nutritional quality of benthic macroinvertebrates, indicated by their polyunsaturated FA (PUFA) concentrations, were taxon- and stressor-specific. Nutritional quality of the larval dragonfly predator, Ophiogomphus, decreased nonlinearly with decreasing benthic diatom abundance and was lowest at the sewage-affected sites, although exposure to natural bitumen also resulted in reduced Ophiogomphus PUFA concentrations. In contrast, the PUFA concentrations of mayfly grazers/collector-gatherers were not affected by natural bitumen exposure, and were higher at the sewage and sewage+mining sites. The PUFA concentrations of the shredder Pteronarcys larvae did not change with cumulative exposure to the stressors. Sediment metal and polycyclic aromatic compound concentrations were not associated with the macroinvertebrate FA changes. Overall, we provide evidence that sewage induced reduction in trophic support by PUFA-rich diatoms, and was the predominant driver of the observed changes in FA composition and nutritional quality of the benthic macroinvertebrates. Fatty-acid metrics are useful to untangle effects of concurrent stressors, but the assessment outcomes depend on the functional feeding guilds used. A food-web perspective using multiple trophic levels and feeding guilds supports a more holistic assessment of the stressor impacts.

Understanding the Coleoptera community at the tree‐line using taxonomic and functional guild approaches

Abstract Mountain species are at the forefront of climate change disruption, and montane saproxylic Coleoptera are facing large‐ and small‐scale changes in their surroundings. Saproxylic Coleoptera are both functionally and taxonomically diverse and are the representatives of an imperilled fauna confronted with the realities of a changing landscape. Understanding the effects of elevation and other forest characteristics on saproxylic and non‐saproxylic Coleoptera is a step towards predicting the future of taxonomic and functional group biodiversity at the tree‐line and on mountains. The objective of this study was to examine the effect of elevation and other forest characteristics on the biodiversity of montane Coleoptera at the tree‐line using both taxonomic and functional feeding guild classifications. Our results suggest that abundance of saprotrophs is closely linked to the density of large trees rather than the volume of wood. Edge effects and elevation seem to drive abundance patterns of some species and also influence taxonomic and functional guild community patterns differently. Finally, we discuss the implications of climate change and land abandonment to future Coleoptera community structure.

Longitudinal patterns of abundance, diversity and functional feeding guilds of benthic communities in East African tropical high‐altitude streams

AbstractIn temperate and tropical rivers, macroinvertebrates are commonly utilised for biological monitoring. Therefore, it is important to understand their functional feeding guilds and assemblage structure. However, there have been few studies in high‐altitude rivers in East Africa aimed at assessing macroinvertebrate functional guilds. In this study, we examined the macroinvertebrate assemblage characteristics using abundance/diversity metrics and the functional feeding groups (FFGs). We collected physicochemical data and macroinvertebrate samples at seven sites along the Gura River and three sites on the Sagana River. Dissolved oxygen concentration, water temperature, electrical conductivity, pH, turbidity, ammonia, and soluble reactive phosphorus showed significant differences among the sites (p < 0.05). A total of 32 families belonging to 11 orders of macroinvertebrates were collected during the study period. Overall, scrapers were the most abundant FFG, dominated by Heptageniidae (Afronurus). Collector filters and collector gatherers were the second most abundant, while shredders and predators exhibited the least relative abundance. Across all the dominant orders, macroinvertebrate abundance decreased from upstream to downstream sites, with upstream sites exhibiting high diversity and abundance of Ephemeroptera, Diptera, Coleoptera, and Trichoptera taxa. Furthermore, the FFGs in this study differed widely from the River Continuum Concept predictions. Our findings provide crucial understanding of macroinvertebrate assemblage characteristics in high‐altitude rivers. Thus, this study provides additional evidence on the high abundance and diversity of Ephemeroptera and Trichoptera taxa in tropical rivers.

Niche specialization and community niche space increase with species richness in filter‐feeder assemblages

AbstractEcological theory posits that higher species richness should be associated with greater exploitation of resources and niche packing resulting from either increasing species niche overlap or specialization of species' niches. Research evaluating niche theory in animals tends to focus on organisms among functional feeding guilds, while resource partitioning might be more critical within functional groups. Freshwater mussels (Family: Unionidae) are a diverse and imperiled group of animals that are ideal models to test niche occupancy due to their functional similarity as filter‐feeders and their occurrence in spatially and temporally stable multispecies aggregations. We evaluated the relationship between species richness and the trophic niche area for 25 mussel species occurring in 22 aggregations in the southeastern United States using stable isotope analysis (δ13C and δ15N) of soft tissue (n = 1057). Mean species standard ellipse area decreased with species richness, whereas ellipse overlap was not related to richness, indicating increased niche specialization may be the primary mechanism allowing coexistence in species‐rich communities. Total community isotopic area increased with richness, suggesting species‐rich communities also use a broader range of resources and may not be species‐saturated. Overall, our data support the niche‐packing hypothesis by illustrating the importance of niche partitioning within a species‐rich guild of aquatic animals.

Gold mining impairs the biological water quality of a culturally important river and UNESCO World Heritage Site in Nigeria

The UNESCO World Heritage Sites have special conservation regulations because they are recognized as having significant cultural and/or natural value. One of Nigeria's two UNESCO-designated World Heritage Sites is the Osun River. It has immense biodiversity values, which are currently being threatened due to gold mining activities within its catchment area. Thus, this study seeks to ascertain the current biological water quality of this culturally and internationally important river using ecological and ecotoxicological approaches. Samples were collected from three environmental compartments (i.e., water, benthic sediment, and macroinvertebrates) in both dry and wet seasons from the section of the river that flows through the UNESCO site. Findings revealed that the river's physiochemical water quality has immensely degraded on account of extremely high total suspended solids, extremely low water transparency, and low dissolved oxygen. Three heavy metals exceeded their permissible limits in drinking water; i.e., Cd (364–367 times higher), Pb (75–104 times higher), and As (35–67 times higher). The contamination factor indicated that the benthic sediments were contaminated with Cd and Au, while the geo-accumulation (Igeo) index only indicates contamination on account of Cd, though Au ranks second in order of Igeo. The composition of the river's macroinvertebrate fauna suggests that it has been severely impacted because there was almost no stress-sensitive Ephemeroptera-Plecoptera-Trichoptera taxon present (one taxon and one individual only). Almost all of the chosen heavy metals had bioaccumulated in the three functional feeding guilds of macroinvertebrates. The current levels of heavy metals in the three environmental compartments of the river pose a great risk to both freshwater biodiversity and human health. Thus, a re-channeling of the upstream effluents from the river or any other natural water is advised. Also, a periodic environmental audit of the river should be conducted until it recovers from the pollution stress.

Microplastics and leaf litter decomposition dynamics: New insights from a lotic ecosystem (Northeastern Italy)

Microplastics represent one of the main environmental concerns of our time and their presence is well known in all freshwater ecosystems. However, there is still a lack of knowledge about the interference with some environmental dynamics, such as the leaf litter decomposition, which represents a key process in freshwater ecosystems. The work presented herein analyzed the leaf litter decomposition in a lotic ecosystem, in relation to water physicochemical parameters, macrobenthic invertebrate functional feeding guilds (FFG) and, as a novelty, the microplastics as additional factor. Physicochemical features were monitored every 15 days for one year. Phragmites australis decomposition rates were investigated during four seasons (summer, autumn, winter, and spring) using the leaf bag technique. Microplastic items were also collected within the leaf bags (used as retaining tool) and within macrobenthic invertebrate colonizers. Shredders were the most contaminated FFG in summer and autumn, while scrapers showed high microplastics levels in autumn and winter. Decomposition rates significantly differed among seasons (0.007 < k < 0.022) and water temperature was the main driver of the decomposition dynamics (relative importance = 70.3 %), positively affecting the decay rates, followed by pH (9.7 %), which showed a negative contribution. Microplastics showed a negative effect (3.1 %), with a relative importance similar and opposite to that observed for the shredders (3.9 %), which value was similar to those recorded for scarpers (2.7 %). This study represents a field investigation regarding the microplastic effects on the organic matter decomposition rates in freshwater environments carried out directly on field. Our results provide new insights about the microplastic interference on environmental dynamics and could represent a starting point for further studies.

Gastropod Assemblages Associated with Habitat Heterogeneity and Hydrological Shifts in Two Shallow Waterbodies

We aimed to determine the effects of water level and habitat heterogeneity on gastropod fauna in the littoral zone, and the differentiation of functional feeding guilds (FFG) of gastropods. Two periods were analyzed: 2012 (low water level, LWL) and 2013 (high water level, HWL) in the littoral zone of two shallow waterbodies (Sutla backwater, NW Croatia). Waterbody S1, covered with Ceratophyllum demersum, was sampled in the macrophyte stands, and the littoral benthal area, while waterbody S2, without macrophytes, was sampled only in the littoral benthal area. It was observed discovered that among the macrophyte stands in S1, gastropods were significantly more abundant during LWL. The same trend was observed in the littoral benthal area of S2. In contrast, gastropod abundance was higher in the littoral benthal area of S1 during HWL. Comparing gastropods in the two waterbodies, the abundance in S1 was ten times higher than in S2. The most abundant species was Gyraulus parvus, which accounted for 51–92% of the gastropods observed among the macrophytes of S1 and 86% in the adjacent benthic zone. Among the FFG groups, grazers (particularly those feeding on gymnamoebae and rotifers) had the largest proportion, followed by shredders feeding on small pieces of macrophytes. In our research, we indicate the important role of microhabitat diversity and submerged macrophytes as a rich food source for gastropods and safe shelter from predators.

Biodiversity and Litter Breakdown in a Karstic Freshwater System (Doberdò Lake, Northeast Italy) in Relation to Water Level Fluctuations and Environmental Features

The present study reports seasonal data about chemico-physical trends, macrobenthic invertebrates, and Phragmites australis decomposition rates within a karstic freshwater system in the western classic Karst. Results presented herein were compared with those obtained from the same system five years ago. Chemico-physical data showed higher temperatures and lower levels of pH and conductivity than in the past. The macrobenthic invertebrate community varied through the seasons and through the years, though they are dominated by few taxa, such as Asellus and Gammarus. These shredders were the most abundant functional feeding guild, playing a pivotal role in the decomposition of the vegetal organic matter. Decomposition rates k ranged between 0.009 and 0.016 days−1 and varied seasonally. k values were different from those previously reported for the investigated system. Differences are mainly due to changes in water supply, depending on decreasing rainfall regimes and hydrometric levels of the Soča River, which showed lower levels than in the previous study. Changes in water supply altered the fluctuating pulse that is typical of ephemeral karstic lakes, changing the system dynamics. Potential effects of climate change on local scale are also discussed.

Seasonal variation and crop diversity shape the composition of bird communities in agricultural landscapes in Nepal

Farmland birds are declining globally due to anthropogenic activities, with particularly few studies in Asian agricultural landscapes. Various studies have examined the impacts of landscape heterogeneity on farmland bird composition, but few have considered seasonal changes in bird diversity and examined functional feeding guild assemblages. Here, we disentangle the impact of seasonal variation (summer, monsoon, and winter), cropping practice (mixed crop, monocultural-crop, and fallow land), crop type (rice, wheat, maize, sugarcane, and other crops), landscape heterogeneity, and the number of houses and trees on the richness and abundance of farmland birds and their feeding guilds conducted within human-dominated agricultural landscapes of lowland Nepal. We established 116 transects (farmland = 100, forest = 8, and river = 8), and each transect was visited nine times from April 2018 to December 2019, with forests and river transect to test the dissimilarities in bird composition between those habitats and farmlands. We recorded 201 bird species in farmland, 133 in the forest, and 131 in river habitats. Bird composition on farmlands showed more dissimilarity with forest than river transects. We recorded nine globally, and 26 nationally threatened birds in farmlands. Seasonal variation and cropping practice significantly influenced the richness of all farmland birds and resident birds only, whereas species abundances vary by season only. We recorded higher species richness in the winter season and mixed crop fields but greater abundance in the monsoon and monoculture crop fields. Farmland bird richness increased with increasing tree numbers but decreased with increasing house numbers. Sugarcane fields had the highest bird richness within crop species, whereas rice fields had the greatest abundance. Seasons and cropping practice also shaped the assemblages of feeding guilds differently. In the context of increasing crop intensification globally, our study suggests that the governments in this region should encourage farmers to cultivate mixed crops and simultaneously restrict the urbanization of farmlands to protect bird diversity. Seasonality should be factored into analyses aimed at understanding bird diversity in agricultural landscapes.

Taking advantage of transparency: A proof-of-principle for the analysis of the uptake of labeled microplastic particles by organisms of different functional feeding guilds using an adapted CUBIC protocol

The analysis of the ingestion of microplastics (MP) by biota is frequently performed through invasive procedures such as chemical digestion protocols or by histological analysis of thin sections. Different, promising approaches for the observation of ingested MP particles pose so called tissue clearing methods. They are currently applied to organs, tissue samples, or whole organisms, rendering the sample transparent and enable to look inside an otherwise opaque environment. To date, there is a lack of methods to detect labeled MP inside an opaque organism's digestive tract without interfering with the sample's integrity. Therefore, our goal was to adapt the CUBIC tissue clearing protocol (Clear, Unobstructed Brain/Body Imaging Cocktails and Computational Analysis) for aquatic and terrestrial organisms of various functional feeding groups for the analysis of the uptake of fluorescent labeled microplastic (MP) particles. We included the buff-tailed bumblebee Bombus terrestris, the compost worm Eisenia fetida, the woodlouse Porcellio scaber, the freshwater shrimp Gammarus roeselii, and the quagga mussel Dreissena bugensis in the analysis. The adapted CUBIC method has led to transparency in all normally opaque organisms. It further offers a simple way of locating fluorescent labeled MP inside the digestive system of the different organisms while leaving them intact.

Ecosystem Response Through a Resilience Lens: Do Differences in the Illinois River Over 150 Y Indicate Regime Shifts?

AbstractMost of the world's large river ecosystems are subject to multiple anthropogenic stressors including climate change, disconnection between the main river channel and floodplain, flow regulation, and land‐use modification. Viewed through a resilience lens, these ecosystems are potentially in a new regime, exhibiting a different structure, function, and set of feedbacks. We investigated the trophic status and food web character response to anthropogenic stressors over 150 years in the Illinois River. Differences in stable isotope ratios, community niche space, basal resource contribution to higher levels in the food web, mean trophic position of fish functional feeding guilds, and food chain length among four stressor phases suggest changes in ecosystem function in the Illinois River. Moreover, the river did not return to pre‐stressor conditions following watershed‐wide restoration efforts. Differences in trophic status and food web character also varied between the upper‐ and lower‐river zones of the Illinois River over time. This spatial divergence further highlights the complexity of responses to multiple stressors in this ecosystem. Overall, differences in trophic status and food web character suggest a shift to a new regime–an Anthropocene regime–and one that has a reduced capacity to absorb additional disturbances. Given human pressures are a global issue, our results based on a 150 years data set, could assist in the management of riverine landscapes that face regime shifts due to human stressors.

Jigsaw dissection activity enhances student ability to relate morphology and ecology in aquatic insects

ABSTRACT Functional feeding guild classification of aquatic insects is partly based on mouthpart morphology, but the link between mouthpart morphology and ecological feeding roles is often missed by students in the classroom. We implemented a Jigsaw activity in a freshwater biology course to help students connect morphology and ecology. Paired students dissected two common (to the whole class) and one unique aquatic insect’s mouthparts and predicted their ecological feeding roles. Students then divided into new groups and taught peers about their unique insect. A pre- and post-activity survey measured students’ ability to relate morphology and feeding roles. Open-ended questions graded via a rubric showed students scored significantly higher and provided more answers discussing feeding roles. Likert-type questions probing students’ perceptions of mouthpart importance resulted in marginally higher importance ratings of mouthparts for identification but no differences for insect feeding. On an end-of-the-semester assessment, students generally rated the activity as helpful. Some reported the activity to be difficult due to small insect size. The activity enhanced students’ understanding of the link between mouthparts and feeding roles but may have decreased their engagement due to perceived difficulty. Further modification alleviating difficulty may improve student perceptions while retaining knowledge gains.

Habitat quality and edge area of fragments determine insect diversity in a heavily used landscape: Implications for forest landscape restoration

AbstractWorldwide, forest fragmentation and degradation have affected the flora and fauna, and are threatening the livelihood of people depending upon forest resources. It is essential to understand the underlying ecological processes to better manage such landscapes. In ecological assessments, insects are useful tools to assess the effects of human interventions such as restoration, as insects are vital for several ecosystem processes. Therefore, we studied the ecological processes that determined the distributions of the epigeic insect communities among the degraded forest fragments of the Attappady Hills (Western Ghats, India), which are being restored. Our objectives were to determine the spatial variations in the epigeic insect communities and their responses to habitat quantity and quality of the forest fragments, along with an assessment of the invasive ants’ responses to fragmentation and degradation, and their effects on the native insect communities. We used pitfall traps in several forest fragments representing varying disturbance levels along an east–west gradient. The diversity of various insect taxonomic groups and functional feeding guilds were higher in smaller fragments than compared to larger fragments due to edge effects. The variations in the distributions of insect communities were explained by the habitat features that were spatially correlated. Invasive ants, Anoplolepis gracilipes, infested the smaller fragments where the vegetation quality had degraded. We conclude that an understanding of the effects of fragmentation and degradation on insect communities is vital to restoration managers as ecological restoration becomes an important strategy to reverse degradation and to revive ecological processes of fragmented forests.Abstract in Malayalam is available with online material.

Microplastics accumulation in functional feeding guilds and functional habit groups of freshwater macrobenthic invertebrates: Novel insights in a riverine ecosystem

Microplastics pose a major threat for aquatic ecosystems, but the contamination dynamics in organisms inhabiting freshwater ecosystems is still little studied. Largely used for biomonitoring, macrobenthic invertebrates provide a pivotal trophic resource for many fish and bird species. In this study, we investigated the microplastics contamination in a macrobenthic invertebrate community (2772 individuals belonging to 33 taxa identified) in a high-plain riverine ecosystem (Vipacco River, northeast Italy) and compared the amount of microplastics accumulated in functional feeding guilds/functional habit groups. Microplastics (cellulosic fibers associated with polyester) were found in 48.5% of the taxa, with the highest amount detected in the collector-gatherers, followed by predators. The collector-gatherers showed a significantly higher microplastic accumulation than the other functional feeding guilds, whereas there was no difference among the functional habit groups. The main source of microplastics pollution was most likely urban wastewater discharge points located along the river. Our study reports a novel approach about microplastic pollution assessment in lotic environments, as it focuses into the microplastic contamination dynamics in an entire macrobenthic invertebrate community perspective and underlines the need for further study.

Predicting Macroinvertebrate Responses to Water Abstraction in Alpine Streams

Exploitation of hydropower potential in alpine areas undermines the ecological integrity of rivers. Damming and water abstraction substantially alter the physical habitat template of rivers, with strong repercussions on aquatic communities and their resources. Tools are needed to predict and manage the consequences of these alterations on the structure and functioning of macroinvertebrate communities and resource availability in alpine streams. We developed habitat preference models for taxa, functional feeding guilds, and organic resources to quantify the effects of discharge alteration on macroinvertebrate communities in two alpine streams. Our physical habitat model related an indirect measure of bottom hydraulic forces (FST hemispheres) to the distribution of macroinvertebrate taxa and their resources. We observed that flow-dependent habitat availability for macroinvertebrate communities generally decreased with increasing water abstraction. We were able to relate these changes to near-bed hydraulic conditions. Our results suggest, however, the existence of upper discharge thresholds delimiting optimal habitat conditions for taxa. In contrast, we found weak effects of near-bed hydraulic conditions on resource distribution. Overall, our findings contribute towards predicting the impacts of water abstraction on macroinvertebrate communities in small alpine streams and the benefits of baseflow restoration.

Complex soil food web enhances the association between N mineralization and soybean yield – a model study from long-term application of a conservation tillage system in a black soil of Northeast China

Abstract. Long-term (10 years) application of conservation tillage following conversion from conventional tillage (CT) can achieve a new equilibrium in the soil environment, which is vital to reverse soil biodiversity declines and fulfil the goal of maintaining agroecosystem sustainability. However, in such a situation, how the soil community regulates nutrient cycling impacting crop yield is not well documented. Therefore, the relations between mineralized nitrogen (N) delivered by soil food web and soybean (Glycine max Merr.) yield were investigated after 14 years application of CT, reduced tillage (RT) and no tillage (NT) in a black soil (Typic Hapludoll) of Northeast China. We hypothesized that soil mineralizable N would increase with the complexity of the soil food web, and that the trophic groups involved in associating N mineralization with crop yield will vary with soil depth in the conservation tillage practice. During the soybean growing season, soil organisms, including bacteria, fungi, nematodes, mites and collembolans, were extracted and identified monthly from 0–5 and 5–15 cm soil depths to estimate the complexity of the food web indicated by the species richness and connectance indices, and to simulate the mineralized N using energetic food web modelling. The species richness and connectance of the food web at both soil depths were significantly affected by tillage practices, and their values decreased of the order of NT &gt; RT &gt; CT. A similar trend was also revealed for the simulated N mineralization, that is, the mineralized N released either from the functional feeding guilds or from the energy pathways of the food web were greater in RT and NT than in CT at both soil depths. Multiple linear regression analysis showed that soil organisms involved in coupling the mineralized N with soybean yield were different at different soil depths, in which fungal and root pathways at 0–5 cm and bacterial pathway at 5–15 cm were the driving factors for the supply of mineralized N to soybean in NT and RT soils. These results support our hypothesis and highlight the essential role of soil food web complexity in coupling N mineralization and crop yield after long-term application of conservation tillage. Additionally, the current modelling work provides basic hypotheses for future studies to test the impact of soil biodiversity or specific functional guilds on the fate of N in agro-ecosystems.

Influence of Weed Management Practices on Ground-dwelling Arthropod Assemblages in Organic and Conventional Apple Orchards

Ground-dwelling arthropods are important components in apple orchard providing beneficial ecological services of predation and decomposition as well as herbivory. Groundcovers are managed differentially in organic and conventional apple orchards influencing ground-dwelling arthropod assemblages. We conducted 3-year studies to assess the effects of orchard management relative to weed management on the abundance and diversity of ground-dwelling arthropods using pitfall trapping. Most arthropods were classified as higher taxonomical groups and functional feeding guilds, while carabid beetles were classified into species level. Coleoptera was the dominating taxon of all ground-dwelling arthropods. Abundance of herbivores and predators was significantly higher in organic apple orchards than conventional ones. Higher abundance and diversity of carabid beetles were found in organic orchards than in conventional orchards. The abundance of Araneae, Coleoptera, or carabid beetles was negatively correlated to weed management frequency. It was found that ground-dwelling arthropods were more influenced by weed management practices than the farming systems.

Winter bird abundance, species richness and functional guild composition at Delhi’s ponds: does time of day and wetland extent matter?

Abstract Urbanisation can limit species persistence and bias composition of functional guilds with serious consequences for ecosystem functioning and conservation planning. Standardised biodiversity surveys are missing at most tropical urban cities where biodiversity levels are high alongside rapidly increasing rates of urbanisation. We explored the utility of time-bound surveys to document winter birds at ponds (wetlands ≤ 5 ha) in Delhi, India at two different times of the day (morning and evening) and in areas with varying extents of wetlands. Systematic surveys at 39 ponds during January–March 2020 yielded an estimated 173 ± 22 bird species (∼37% of Delhi’s birds). The total bird species assemblage at ponds did not vary significantly with time of day, but β-diversity increased marginally with increasing extent of wetlands. Total bird abundance and species richness varied substantially with time of day, with differences apparent across several species rich functional feeding and habitat guilds. Abundance and species richness of some guilds, including species-poor guilds, varied in ponds located in areas with differing extent of wetlands. Reliable and comparable measures of species abundance and species richness (both total and across functional guilds)— metrics commonly used to set research and conservation priorities—in urban habitats can be obtained after appropriately standardising field effort. Such standardised efforts can help underscore the importance of maintaining and improving erstwhile-ignored habitats such as unprotected ponds that are providing refugia to hundreds of bird species in mega-cities like Delhi.