Changes in Biomass and Diversity of Soil Macrofauna along a Climatic Gradient in European Boreal Forests

Latitudinal gradients allow insights into the factors that shape ecosystem structure and delimit ecosystem processes, particularly climate. We asked whether the biomass and diversity of soil macrofauna in boreal forests change systematically along a latitudinal gradient spanning from 60° N to 69° N. Invertebrates (3697 individuals) were extracted from 400 soil samples (20 × 20 cm, 30 cm depth) collected at ten sites in 2015–2016 and then weighed and identified. We discovered 265 species living in soil and on the soil surface; their average density was 0.486 g d·w·m−2. The species-level diversity decreased from low to high latitudes. The biomass of soil macrofauna showed no latitudinal changes in early summer but decreased towards the north in late summer. This variation among study sites was associated with the decrease in mean annual temperature by ca 5 °C and with variation in fine root biomass. The biomass of herbivores and fungivores decreased towards the north, whereas the biomass of detritivores and predators showed no significant latitudinal changes. This variation in latitudinal biomass patterns among the soil macrofauna feeding guilds suggests that these guilds may respond differently to climate change, with poorly understood consequences for ecosystem structure and functions.

Cyclone Amphan effects on the copepods of Ganges estuary

Tropical cyclones are increasingly affecting the estuarine communities. Impacts of category-5 tropical cyclone Amphan (landfall on 20 May 2020 near Ganges estuary mouth) on the copepod community of Muriganga section of Ganges estuary was studied by sampling the copepod assemblages before (February to December 2019), shortly after (31 May to 12 June 2020) and post (September to November 2020) cyclone. Hypothesis was shortly after Amphan a relatively homogenous community consists of a few estuarine specialist copepods would succeed but within months that community would be replaced by a heterogenous one but those estuarine specialists would continue their dominance. Shortly after Amphan, species richness declined but the recovery process completed within months led by herbivorous Paracalanus parvus, omnivorous Bestiolina similis, Acartia spinicauda, Acartiella tortaniformis, and carnivorous Oithona brevicornis. Spatial homogeneity of the community that prevailed in Muriganga in pre-Amphan and shorty after Amphan was lost in post-Amphan. Community composition changed from pre- to shortly after to post-Amphan. Unilateral dominance of B. similis observed in pre-Amphan was challenged by P. parvus, A. spinicauda, A. tortaniformis and O. brevicornis shortly after Amphan and in post-Amphan. Acartia spinicauda proliferated shortly after Amphan and co-dominated the estuary along with A. tortaniformis but the latter replaced the former in post-Amphan. Copepods did rebuild their community within a few months from Amphan but experienced rearrangements of species composition, abundance, dominance hierarchy and feeding guilds, which may strain benthic-pelagic linkages of Ganges estuary so shall be monitored regularly by coastal institutions following uniform methods and best practises.

Trophic guilds of suction-feeding fishes are distinguished by their characteristic hydrodynamics of swimming and feeding

Suction-feeding in fishes is a ubiquitous form of prey capture whose outcome depends both on the movements of the predator and the prey, and on the dynamics of the surrounding fluid, which exerts forces on the two organisms. The inherent complexity of suction-feeding has challenged previous efforts to understand how the feeding strikes are modified when species evolve to feed on different prey types. Here, we use the concept of dynamic similarity, commonly applied to understanding the mechanisms of swimming, flying, walking and aquatic feeding. We characterize the hydrodynamic regimes pertaining to (i) the forward movement of the fish (ram), and (ii) the suction flows for feeding strikes of 71 species of acanthomorph fishes. A discriminant function analysis revealed that feeding strikes of zooplanktivores, generalists and piscivores could be distinguished based on their hydrodynamic regimes. Furthermore, a phylogenetic comparative analysis revealed that there are distinctive hydrodynamic adaptive peaks associated with zooplanktivores, generalists and piscivores. The scaling of dynamic similarity across species, body sizes and feeding guilds in fishes indicates that elementary hydrodynamic principles govern the trophic evolution of suction-feeding in fishes.

Insight into the role of cyanobacterial bloom in the trophic link between ciliates and predatory copepods

An important group of protozooplankton, the ciliates, are a crucial component of aquatic food webs. They are the main grazers on bacteria and algae transferring carbon to higher levels of the food web (metazooplankton and fish fry). Changes in the quality and quantity of protozooplankton can modify the quality and quantity of metazooplankton, especially predatory copepods, causing changes in energy transfer and the matter cycle. Observable climate change is one of the most significant factors promoting the increase of cyanobacterial blooms. Therefore, the aim of this study was to find out how cyanobacterial blooms modify relationships between ciliates (prey) and copepods (predator), and to discover possible pathways of changes in freshwater food webs. We analysed the relationship between the biomass of predatory copepods and feeding guilds of ciliates (algivorous, bacterivorous, bacteri-algivorous). The relationship of predators biomass with algivorous and bacteri-algivorous ciliate biomasses, with a simultaneous lack of relationship with bacterivorous ciliate biomass, demonstrates that bacterial fixed carbon may be only partially contributing to the total energy passed through this link. Results demonstrated that the bloom enhanced the relationship between prey and predator. Larger and free-swimming ciliate species appear to play a greater role in energy transfer than smaller sedentary species.

Invasive Water Hyacinth Limits Globally Threatened Waterbird Abundance and Diversity at Lake Cluster of Pokhara Valley, Nepal

Invasive species alter ecosystem structure and functioning, including impacts on native species, habitat alteration, and nutrient cycling. Among the 27 invasive plant species in Nepal, water hyacinth (Eichhornia crassipes) distribution is rapidly increasing in Lake Cluster of Pokhara Valley (LCPV) in the last several decades. We studied the effects of water hyacinth on threatened waterbird abundance, diversity, and physico-chemical parameters of water in the LCPV. We found areas with water hyacinth present (HP) had reduced threatened water bird abundance relative to areas where water hyacinth was absent (HA; p = 0.023). The occurrence of birds according to feeding guilds also varied between water hyacinth presence and absence habitats. Piscivorous birds were more abundant in HA areas than HP areas whereas insectivorous and omnivorous birds had greater abundance in HP areas than in HA areas. Threatened waterbird abundance and richness were greater in areas with greater water depth and overall bird abundance but declined in HP areas. Degraded water quality was also identified in HP areas. Our findings can be used as a baseline by lake managers and policy makers to develop strategies to remove or manage water hyacinth in LCPV to improve waterbird conservation.

Good Things Come in Larger Packages: Size Matters for Fruit-feeding Butterfly Dispersal and Diet Breadth

Introduction: Body size is correlated with many aspects of an animal species' natural history, such as life span, abundance, dispersal capacity and diet breadth. However, contrasting trends have been reported for the relationship between body size and these ecological traits. Methods: Butterfly species from fruit-feeding guilds were used to investigate whether body size correlates with species abundances, dispersal, permanence, and diet breadth in a Neotropical savanna in Brazil (Cerrado). We used Blomberg’s K and Phylogenetic Generalized Least Squares models (PGLS) to measure phylogenetic signal strength in species traits, and to estimate size-dispersal-diet breadth associations while taking shared ancestry into account. Results: 539 individuals from 27 species were captured, and 190 individuals were recaptured, representing a 35% recapture rate. We found that body size negatively influenced butterfly abundance. In contrast, body size was positively associated with dispersal levels, distance traveled, number of traps visited, individual permanence, and diet breadth. These results indicate that larger butterflies have a greater proportion of dispersing individuals over longer distances, as they permanence were detected over longer periods than their smaller relatives. Moreover, larger butterflies are more generalized, based on the number of host plant families and genera they consume. Smaller butterflies demand fewer resources, which is reflected in their higher survival in small patches, and may explain their lower dispersal ability, and higher diet specialization. Nevertheless, lower dispersal ability, if not compensated by large population sizes, may threaten small-bodied species inhabiting environments with intense deforestation rates, such as the Cerrado. Conclusions: Body size positively influences dispersal and diet breadth in the fruit-feeding butterflies collected in this study.

Land-use change to subsistence farming has negligible impact on birds in Zimbabwe

Habitat alterations that often accompany land-use change are one of the major drivers of global biodiversity losses. In Africa, these threats are especially severe, as this continent has the most rapidly growing of all human populations. Inevitably, increasing areas of land are being transformed for agriculture, including drought-prone drylands in southern and central Africa, despite often having poor soils. In Zimbabwe, a land reform programme provided a unique opportunity to study the biodiversity response to abrupt habitat modification in an extensive dryland area of mixed grassland and woodland savannah. Small-scale subsistence farms were created rapidly during 2001-2002 in formerly semi-natural savannah. We measured the changing compositions of bird communities in transformed and untransformed land over an 8-year period, commencing one decade after subsistence farms were established. Over the study period, repeated counts were made along identical transects in order to assess species’ population changes that may have resulted from trait-filtering responses to habitat disturbance. We recorded significantly increased abundances in both land-use areas, accompanied by increases in species diversity and functional redundancy. Temporal trends showed increased abundances across all feeding guilds, and in species of virtually all sizes. Influxes of new species did not increase functional traits’ diversity, and no species with distinctive traits appear to have been lost as a result of land-use change. Nearly two decades after habitat transformation, the bird communities in the transformed and untransformed areas had become more similar in composition. The broadly benign impact on birds of land conversion into subsistence farms is attributed to the relatively low-level of human activities and disturbance in the transformed land, and the large regional pool of non-specialist bird species.

AVIFAUNA DO SOLO SAGRADO DO GUARAPIRANGA (SÃO PAULO, BRASIL)

AVIFAUNA OF THE SACRED SOIL OF GUARAPIRANGA (SÃO PAULO, BRAZIL): The avifauna of São Paulo, the largest Brazilian city, is one of the most studied in Brazil. However, some areas are lacking basic studies on the avifauna, including those under intense pressure from urban growth and deforestation. Here we present a list of bird species occurring in the Solo Sagrado do Guarapiranga (23°45’00”S, 46°44’00”W), an urban park in southern São Paulo. We carried out monthly bird surveys from July 2008 to June 2009, using transect method. After 250 hours of observations, we recorded 180 species, including 31 species endemics to Atlantic Forest and two species that are globally threatened. The insectivorous, omnivorous and frugivorous species were the most represented feeding guilds, with 70, 39 and 21 species, respectively. Occasional and rare species composed the community majority. The high species richness and the presence of threatened species indicate the importance of the area to the bird’s conservation in the largest Brazilian city.