Omnivorous Species Research Articles

Feeding ecology of the African cuttlefish Sepia bertheloti (Cephalopoda: Sepiidae) in western Africa

The African cuttlefish, Sepia bertheloti, is a commercially exploited cephalopod in two productive system areas off West Africa. However, there is a lack of information on its feeding ecology, making it difficult to describe its ecological role (Morocco and Guinea-Bissau). In the present study, we analyse the gastric contents of 1.114 individuals, collected between July 2018 and January 2020 using the traditional analysis of stomach contents. A total of 65 and 49 prey items were identified as part of the diet of Moroccan and Guinean African cuttlefish, respectively. The sample size was evaluated using species cumulative curves and the methods used to describe the diet were the frequency of occurrence, number, and weight. Our results suggest that S. bertheloti does not present differences in diet between sexes or areas, although significant differences were observed in terms of prey abundance, richness, and diversity of species. According to the taxonomic groups, crustaceans were the most abundant prey taxa, followed by fish and cephalopods. Amphipods (Gammarus sp.) were the prey that showed the greater importance of occurrence in the diet at both study areas, showing a strictly benthic feeding behaviour. Niche breadth was evaluated using Levin’s index, indicating that S. bertheloti is an omnivorous species (Trophic level ∼3.6) with a heterogeneous diet and without a marked generalist or specialist feeding strategy.

Simulated biomechanical performance of morphologically disparate ant mandibles under bite loading

Insects evolved various modifications to their mouthparts, allowing for a broad exploration of feeding modes. In ants, workers perform non-reproductive tasks like excavation, food processing, and juvenile care, relying heavily on their mandibles. Given the importance of biting for ant workers and the significant mandible morphological diversity across species, it is essential to understand how mandible shape influences its mechanical responses to bite loading. We employed Finite Element Analysis to simulate biting scenarios on mandible volumetric models from 25 ant species classified in different feeding habits. We hypothesize that mandibles of predatory ants, especially trap-jaw ants, would perform better than mandibles of omnivorous species due to their necessity to subdue living prey. We defined simulations to allow only variation in mandible morphology between specimens. Our results demonstrated interspecific differences in mandible mechanical responses to biting loading. However, we found no evident differences in biting performance between the predatory and the remaining ants, and trap-jaw mandibles did not show lower stress levels than other mandibles under bite loading. These results suggest that ant feeding habit is not a robust predictor of mandible biting performance, a possible consequence of mandibles being employed as versatile tools to perform several tasks.

Seasonal dynamics of sea-ice protist and meiofauna in the northwestern Barents Sea

The rapid decline of Arctic sea ice makes understanding sympagic (ice-associated) biology a particularly urgent task. Here we studied the poorly known seasonality of sea-ice protist and meiofauna community composition, abundance and biomass in the bottom 30 cm of sea ice in relation to ice properties and ice drift trajectories in the northwestern Barents Sea. We expected low abundances during the polar night and highest values during spring prior to ice melt. Sea ice conditions and Chlorophyll a concentrations varied strongly seasonally, while particulate organic carbon concentrations were fairly stable throughout the seasons. In December to May we sampled growing first-year ice, while in July and August melting older sea ice dominated. Low sea-ice biota abundances in March could be related to the late onset of ice formation and short time period for ice algae and uni- and multicellular grazers to establish themselves. Pennate diatoms, such as Navicula spp. and Nitzschia spp., dominated the bottom ice algal communities and were present during all seasons. Except for May, ciliates, dinoflagellates, particularly of the order Gymnodiales, and small-sized flagellates were co-dominant. Ice meiofauna (here including large ciliates and foraminifers) was comprised mainly of harpacticoid copepods, copepod nauplii, rotifers, large ciliates and occasionally acoels and foraminifers, with dominance of omnivore species throughout the seasons. Large ciliates comprised the most abundant meiofauna taxon at all ice stations and seasons (50–90 %) but did not necessarily dominate the biomass. While ice melt might have released and reduced ice algal biomass in July, meiofauna abundance remained high, indicating different annual cycles of protist versus meiofauna taxa. In May highest Chlorophyll a concentrations (29.4 mg m−2) and protist biomass (107 mg C m−2) occurred, while highest meiofauna abundance was found in August (23.9 × 103 Ind. m−2) and biomass in December (0.6 mg C m−2). The abundant December ice biota community further strengthens the emerging notion of an active biota during the dark Arctic winter. The data demonstrated a strong and partially unexpected seasonality in the Barents Sea ice biota, indicating that changes in ice formation, drift and decay will significantly impact the functioning of the ice-associated ecosystem.

Urbanisation-induced changes in the morphology of birds from a tropical city

ABSTRACT Urbanisation is accompanied by major environmental changes that impact the structure and functioning of communities and ecosystems, bringing new selective regimes for animal species and for eco-evolutionary dynamics. We aimed to evaluate whether urban intensification promotes ecomorphological changes in birds from a large city in Central Brazil. Analyses were performed on a set of 1314 individuals of 35 species, captured along a gradient of urban intensification. We found significant morphological changes associated with urban intensification by evaluating ten ecomorphological traits and body mass of the species assemblage. Beak length showed the most dramatic changes, and was significantly shorter as a function of urban intensification, mainly in individuals of insectivorous and omnivorous species. These results reinforce the notion that environmental changes caused by human activities in dense urban environments promote new selective pressures in resident bird species.

Intestinal Enzyme Activity and Enzyme Producing Microbial Flora in Relation to Feeding Behaviour in Some Brackishwater Teleosts

Estimation of digestive enzyme activity, isolation and enumeration of aerobic microbial flora from the gastrointestinal tract of five brackishwater fish species (Mugil cephalus, Liza macrolepis, Mugil Lade, Chanos chanos, Lates calcarifer and Oreochromis mossambicus) of different feeding habits were carried out. The herbivorous (M. cephalus, C. chanos, M. Lade and L. macrolepis) and omnivorous (0. mossambicus) showed marked protease activity, whereas moderate protease activity was recorded in carnivorous L. calcarifer. In the herbivorous and omnivorous fish species the concentration of amylase was moderate to high. A very weak amylase activity was recorded in L. calcarifer. Cellulase activity has been found to be more pronounced in C. chanos, whereas, 0. mossambicus, M. cephalus, M. fade and L. macrolepis showed only moderate cellulase activity. Cellulase activity was weak in L. calcarzfer. Proteolytic, amylolytic, lipolytic and cellulolytic microflora were identified from the culture plates using selective media. The isolates were qualitatively screened on the basis of their extracellular enzyme producing ability. The selected isolates were further quantitatively assayed for protease, amylase and cellulase activities. Proteolytic activity was high in 0. mossambicus, whereas the activity of amylase and cellulase was high in the gastrointestinal tract of C. chanos. Protease activity was exhibited by almost all the bacterial isolates. Maximum activity of protease was exhibited by an isolate from L. macrolepis, followed by an isolate from L. calcartfer. Isolates isolated from 0. mossambicus and C. chanos exhibited high cellulase and amylase activity. Study indicated a distinct microbial source of the digestive enzymes (protease, amylase and cellulase) apart from endogenous sources in fish gut.

Polychaete Diversity and Functional Trait Composition in Subtropical Mangrove Ecosystems

Polychaetes play a vital role in the structure and functioning of benthic communities in mangrove ecosystems. Nevertheless, our understanding of the diversity and functional structure of polychaete assemblages across different habitats in the mangrove ecosystems along the coast of the Persian Gulf and Gulf of Oman is limited. In this study, we investigated the species and trait composition of polychaetes and environmental variables, in vegetated and mudflat habitats of three subtropical mangroves. The results showed that Neanthes glandicincta was widely distributed across all regions and habitats. The three-factor ANOVA showed that the abundance and taxonomic diversity of polychaetes differed significantly between two habitats and three mangrove ecosystems. The abundance of polychaetes was observed to be higher in mud habitats than in vegetated habitats. There was a significant difference in species and trait composition between different regions and habitats. Vegetated habitats had higher proportions of crawler predatory species that are longer lived (3–5 years), with larger body size (80–100 mm), and are upward conveyors, whereas mudflat habitats had higher proportions of mobile (burrower) omnivore species that are moderately lived (1–3 years), with larger body size (>100 mm), and are biodiffusers. The three-factor ANOVA showed a significant difference in the community weighted mean (CWM) index between two habitats and three mangrove ecosystems. Thus, the species and trait composition of polychaetes depend on the structural complexity of their respective habitats. The DistLM analysis showed that total organic carbon content of the sediment was the main predictor variable influencing species composition, while silt/clay content and salinity were the main predictor variables influencing the traits’ composition. The results showed how the composition of traits and the structure of polychaete communities change in mangrove ecosystems, which can be used for future studies on conservation strategies for mangrove ecosystems throughout the world.

Diversified farms bolster forest-bird populations despite ongoing declines in tropical forests

While some agricultural landscapes can support wildlife in the short term, it is uncertain how well they can truly sustain wildlife populations. To compare population trends in different production systems, we sampled birds along 48 transects in mature forests, diversified farms, and intensive farms across Costa Rica from 2000 to 2017. To assess how land use influenced population trends in the 349 resident and 80 migratory species with sufficient data, we developed population models. We found, first, that 23% of species were stable in all three land use types, with the rest almost evenly split between increasing and decreasing populations. Second, in forest habitats, a slightly higher fraction was declining: 62% of the 164 species undergoing long-term population changes; nearly half of these declines occurred in forest-affiliated invertivores. Third, in diversified farms, 49% of the 230 species with population changes were declining, with 60% of these declines occurring in agriculture-affiliated species. In contrast, 51% of the species with population changes on diversified farms showed increases, primarily in forest-affiliated invertivores and frugivores. In intensive farms, 153 species showed population changes, also with similar proportions of species increasing (50%) and decreasing (50%). Declines were concentrated in agriculture-affiliated invertivores and forest-affiliated frugivores; increases occurred in many large, omnivorous species. Our findings paint a complex picture but clearly indicate that diversified farming helps sustain populations of diverse, forest-affiliated species. Despite not fully offsetting losses in forest habitats, diversified farming practices help sustain wildlife in a critical time, before possible transformation to nature-positive policies and practices.

Gill arch and raker morphology of common carp (Cyprinus carpio, Linnaeus, 1758) sampled in aquaculture system.

The study aimed to investigate the morphologic aspects of common carp's gill arch and gill rakers (Cyprinus carpio, Linnaeus, 1758), an omnivore and highest-produced aquaculture species. The study used 10 common carp (395.35 ± 45.06 g) grown entirely under aquaculture conditions. The fish tissues were fixed with Glutaraldehyde (2.5%) for scanning electron microscopy and with formalin (10%) for stereomicroscopic examination. In the SEM examination, two types of taste papillae (Type II and Type III) were observed in the pharyngeal mucosa. Microridge-like structures in the epithelial layer were found to have two forms. The study findings indicate a significant decrease in gill arch lengths from cranial to caudal and a significant increase in rakers per unit area, as determined through digital calliper measurements and stereomicroscopic examinations (p < 0.05). However, there was no significant difference in measurements of gill arches and raker numbers between the bilateral symmetry of the gill arches (p > 0.05). In conclusion, it was observed that the epithelial structure on the common carp gill arch contained two types of microridge-like structures: the gill arch length decreased from cranial to caudal, and the rake density on these arches increased caudally.

Dependency of Arctic zooplankton on pelagic food sources: New insights from fatty acid and stable isotope analyses

AbstractGlobal warming causes dramatic environmental change to Arctic ecosystems. While pelagic primary production is initiated earlier and its intensity can be increased due to earlier ice melt and extended open‐water periods, sea‐ice primary production is progressively confined on a spatio‐temporal scale, leading to unknown consequences for the ice‐associated (sympagic) food web. Understanding ecological responses to changes in the availability and composition of pelagic and sympagic food sources is crucial to determine potential changes of food‐web structure and functioning in Arctic marine communities under increasingly ice‐free conditions. Focus was placed on the importance of suspended particulate organic matter vs. sympagic organic matter for 12 zooplankton species with different feeding modes covering five taxonomic groups (copepods, krill, amphipods, chaetognaths, and appendicularians) at two ice‐covered, but environmentally different, stations in the north‐western Barents Sea in August 2019. Contributions of diatom‐ and flagellate‐associated fatty acids (FAs) to total lipid content and carbon stable isotopic compositions of these FAs were used to discriminate food sources and trace flows of organic matter in marine food webs. Combination of proportional contributions of FA markers with FA isotopic composition indicated that consumers mostly relied, directly (herbivorous species), or indirectly (omnivorous and carnivorous species), on pelagic diatoms and flagellates, independently of environmental conditions at the sampling locations, trophic position, and feeding mode. Differences were nevertheless observed between species. Contrary to other studies demonstrating a high importance of sympagic organic matter for food‐web processes, our results highlight the complexity and variability of trophic structures and dependencies in different Arctic food webs.

The effects of the Patagonian shelf-break front on copepod abundance, biodiversity, and assemblages

Fronts play an important role in ecological processes, having multiple effects on the structure of plankton communities. The Argentine Sea is characterized by the presence of the large and very productive Patagonian shelf-break front (PSBF). This is a permanent front, with high thermohaline gradients defined between the relatively warmer and fresher shelf waters and those of the Malvinas Current. We studied the effects of the PSBF in the vertical and horizontal structure of the copepod community along two transects crossing the front. For all the variables studied, the outer shelf plus the front behaves as a unity, different of the offshore oceanic region. The highest copepod abundances were recorded on the outer shelf and shelf-break front, while the highest diversity was verified in the oceanic regime. Three copepod assemblages were identified associated to different regions: outer shelf and front (OS-PSBF), upper (UMW) and deeper (DMW) Malvinas waters, each one characterized by its own set of indicator species, having different reproductive and feeding strategies. Sac-spawners, ambush or cruise-feeders, and detritivore or omnivore species, occurred in DMW, while broadcasters, filter-feeders and mainly herbivores dominated at UMW and OS-PSBF. The PSBF acts as a leaky boundary between the oceanic regime (UMW and DMW) and the outer shelf-front regime (OS-PSBF), the first one characterized by higher copepod diversity and several functional groups, and the last one depicted by higher copepod abundance and only one functional group. In addition to its high primary production, the PSBF and surroundings are important to provide diversity of pelagic habitats that promote the existence of different assemblages, which are characterized by species having similar functional traits and that could play a similar role in the ecosystem.

Multispecies fish tracking across newly created shallow and deep habitats in a forward-restored lake

BackgroundFreshwater fish communities typically thrive in heterogenous ecosystems that offer various abiotic conditions. However, human impact increasingly leads to loss of this natural heterogeneity and its associated rich fish communities. To reverse this trend, we need guidelines on how to effectively restore or recreate habitats for multiple fish species. Lake Markermeer in the Netherlands is a human-created 70,000-ha lake with a uniform 4 m-water depth, steep shorelines, high wind-induced turbidity, and a declining fish community. In 2016, a forward-looking restoration project newly created a 1000-ha five-island archipelago in this degrading lake, which offered new sheltered shallow waters and deep sand excavations to the fish community.MethodsIn 2020, we assessed how omnivorous and piscivorous fish species used these new habitats by tracking 78 adult fish of five key species across local and lake-scales. We monitored spring arrival of adult fish and assessed local macro-invertebrate and young-of-the-year fish densities.ResultsAdult omnivorous Cyprinidae and piscivorous Percidae arrived at the archipelago in early spring, corresponding with expected spawning movements. During the productive summer season, 12 species of young-of-the-year fish appeared along the sheltered shorelines, with particularly high densities of common roach (Rutilus rutilus) and European perch (Perca fluviatilis). This suggests the sheltered, shallow, vegetated waters formed new suitable spawning and recruitment habitat for the fish community. Despite highest food densities for adult fish in the shallowest habitats (< 2-m), adult fish preferred minimally 2-m deep water. After spawning most Cyprinidae left the archipelago and moved long distances through the lake system, while most Percidae remained resident. This may be related to (1) high densities of young-of-the-year fish as food for piscivores, (2) medium food densities for omnivores compared to elsewhere in the lake-system, or (3) the attractiveness of 30-m deep sand excavations that were newly created and frequently used by one-third of all tracked fish.ConclusionsNew littoral zones and a deep sand excavation constructed in a uniform shallow lake that lacked these habitat types attracted omnivorous and piscivorous fish species within four years. Both feeding guilds used the littoral zones for reproduction and nursery, and notably piscivorous fish became residents year-round.

Fish Gut Microbiome Analysis Provides Insight into Differences in Physiology and Behavior of Invasive Nile Tilapia and Indigenous Fish in a Large Subtropical River in China.

The gut microbiome is thought to play vital roles in host fitness and local adaptation to new environments, thereby facilitating the invasion of the host species. The Nile tilapia (Oreochromis niloticus) (NT) is an aggressive and omnivorous species that competes with native fishes for food resources, and it has successfully invaded much of the Pearl River basin in China. Here, we investigated the gut microbiomes of invasive Nile tilapia and indigenous black Amur bream (BA) in the same river section using high-throughput 16S rRNA gene sequencing. The results indicated that the gut microbiome of NT had several special characteristics, e.g., higher alpha diversity and greater niche breadth, compared with the bream. The gut microbiota of the small size of Nile tilapia (NTS) and small size of black Amur bream (BAS) groups were dominated by Proteobacteria, while those of the NTS and large size of Nile tilapia (NTL) and BAS and large size of black Amur bream (BAL). BAL and NTL were characterized by Firmicutes and Fusobacteriota, respectively. We found that Pseudomonas, Cetobacterium, Ralstonia, and Romboutsia were biomarkers of the NTS, NTL, BAS, and BAL groups, respectively. Moreover, the results collectively suggested that the clustering coefficients of BAL and NTL networks were greater than those of BAS and NTS networks, and BAS had the smallest network among the four groups. Positive interactions between two ASVs dominated the BAS, NTS, and NTL networks, while the proportion of negative interactions between two ASVs in the BAL network was remarkably increased. Low levels of interspecies competition in the NT gut microbiome would contribute to high diversity in the dietary niches and would also benefit the survival and local adaptation of the host. Our results identified specific biomarkers of gut microbial species in invasive Nile tilapia and provided useful information concerning how to monitor and manage invasive Nile tilapia populations.

A test of the green wave hypothesis in omnivorous brown bears across North America

Herbivorous animals tend to seek out plants at intermediate phenological states to improve energy intake while minimizing consumption of fibrous material. In some ecosystems, the timing of green‐up is heterogeneous and propagates across space in a wave‐like pattern, known as the green wave. Tracking the green wave allows individuals to prolong access to higher‐quality forage. While there is a plethora of empirical support for such behavior in herbivorous taxa, the green wave hypothesis (GWH) is nuanced based on factors such as body morphometrics and digestive capacity. Furthermore, little is known about whether other taxa, such as omnivores, track the green wave. Our objective was to assess whether the GWH can be extended to explain the movements of omnivores. Using GPS collar data from seven populations (n = 127 individuals) of brown bears Ursus arctos across their entire North American range, we first tested whether bears tracked the green wave. Using conditional resource selection functions (RSFs), we found that variation in proxies of vegetative forage quality better explained movement and habitat selection than proxies of forage biomass in over half of the bears in our study, providing evidence of green wave tracking. Second, we assess factors that explained variation in green wave tracking using linear mixed effects models. Green wave tracking in brown bears was explained by the variation in availability of green‐up within spring home ranges, and how green‐up transitioned across those home ranges. Our results demonstrate that the GWH can partially explain movement of a non‐migratory omnivorous species, extending the generality of the GWH as a broad predictor of animal space use. The green wave is another resource wave brown bears track, and our findings help predict brown bear space use, which can be used to guide conservation and habitat restoration efforts.

Evolutionary activation of acidic chitinase in herbivores through the H128R mutation in ruminant livestock

Placental mammals' ancestors were insectivores, suggesting that modern mammals may have inherited the ability to digest insects. Acidic chitinase (Chia) is a crucial enzyme hydrolyzing significant component of insects' exoskeleton in many species. On the other hand, herbivorous animal groups, such as cattle, have extremely low chitinase activity compared to omnivorous species, e.g., mice. The low activity of cattle Chia has been attributed to R128H mutation. The presence of either of these amino acids correlates with the feeding behavior of different bovid species with R and H determining the high and low enzymatic activity, respectively. Evolutionary analysis indicated that selective constraints were relaxed in 67 herbivorous Chia in Cetartiodactyla. Despite searching for another Chia paralog that could compensate for the reduced chitinase activity, no active paralogs were found in this order. Herbivorous animals' Chia underwent genetic alterations and evolved into a molecule with low activity due to the chitin-free diet.

A multidimensional framework to quantify the effects of urbanization on avian breeding fitness

AbstractUrbanization has dramatically altered Earth's landscapes and changed a multitude of environmental factors. This has resulted in intense land‐use change, and adverse consequences such as the urban heat island effect (UHI), noise pollution, and artificial light at night (ALAN). However, there is a lack of research on the combined effects of these environmental factors on life‐history traits and fitness, and on how these interactions shape food resources and drive patterns of species persistence. Here, we systematically reviewed the literature and created a comprehensive framework of the mechanistic pathways by which urbanization affects fitness and thus favors certain species. We found that urbanization‐induced changes in urban vegetation, habitat quality, spring temperature, resource availability, acoustic environment, nighttime light, and species behaviors (e.g., laying, foraging, and communicating) influence breeding choices, optimal time windows that reduce phenological mismatch, and breeding success. Insectivorous and omnivorous species that are especially sensitive to temperature often experience advanced laying behaviors and smaller clutch sizes in urban areas. By contrast, some granivorous and omnivorous species experience little difference in clutch size and number of fledglings because urban areas make it easier to access anthropogenic food resources and to avoid predation. Furthermore, the interactive effect of land‐use change and UHI on species could be synergistic in locations where habitat loss and fragmentation are greatest and when extreme‐hot weather events take place in urban areas. However, in some instances, UHI may mitigate the impact of land‐use changes at local scales and provide suitable breeding conditions by shifting the environment to be more favorable for species' thermal limits and by extending the time window in which food resources are available in urban areas. As a result, we determined five broad directions for further research to highlight that urbanization provides a great opportunity to study environmental filtering processes and population dynamics.

Exploring fish functional trait assemblages in Eastern Mediterranean rivers: a study across multiple scales using network analysis

Functional traits of river fish assemblages have rarely been studied in the Eastern Mediterranean region. A dataset of 254 Greek electrofished near-natural sites (427 samples) was analyzed to explore native fish functional structure across three spatial scales: (a) among six ecoregions, (b) within a single ecoregion, and (c) in a river basin. Overall, 76 native fish species were assigned eight functional categories, involving 24 different traits. Bipartite networks were used to interpret spatial patterns of species trait data. Two major trait assemblage types were detected in all three spatial scales: the upland type, dominated by insectivorous, benthic, rheophilic, intolerant species, and the lowland type, incorporating omnivorous, limnophilic, phytophilic, and tolerant species. In order to provide further insights between traits and key environmental variables, redundancy analysis (RDA) was employed. The RDA depicted a strong upstream–downstream environmental gradient. Upland and lowland assemblage types form two distinct functional zones along the upstream and downstream river stretches, respectively. Yet, no consistent boundary criteria seem to exist between them. Notably, within a region of high fish assemblage heterogeneity such as the Eastern Mediterranean, functional patterns follow well-established phenomena along the upstream–downstream longitudinal profile of temperate lotic waters.

Variation of Coral Fish Communities in Coral Transplantation Sites, Kecinan Beach, Malaka Village, North Lombok

Coral reefs are a very complex ecosystem with a fairly high diversity of biota, the existence of coral fish will be greatly affected by the condition of coral reefs, coral transplantation is an effort to restore coral reefs which aims to improve coral reef ecosystems. This study aims to look at the reef fish community in coral transplant media. Data collection was carried out on January 15 – February 26, 2023. The method used in this study was a survey method. Data was collected using the Underwater Visual Census (UVC) technique and underwater cameras using SCUBA equipment. Data collection was carried out 4 times by looking at diversity, abundance, and categories based on how they eat. The results of this study obtained 6 families belonging to 13 genera and 15 species of reef fish with a total of 549 individuals. The categories of fish found consisted of 4 categories, namely 3 species of carnivores, 2 species of herbivores, 8 species of omnivores, and 2 species of corallivores. The diversity index value (H') was 1.662, the uniformity index (E) was 0.613, and the dominance index value (C) was 0.266.

Avian Feeding Guilds in Winter and Rainy Crop Seasons of Guava

A comparative study was conducted on avian feeding guilds in winter and rainy crop seasons of guava at Punjab Agricultural University campus, Ludhiana, Punjab, during 2021-22. A total of 53 bird species belonging to 46 genera, 31 families and 13 orders were noted during the study period. The recorded bird species were classified into six feeding guilds. Except for insectivore, carnivore and omnivore birds, 13 species were recorded to play no beneficial role in the combined data of winter and rainy crop seasons. Relative abundance of insectivore bird species was found to be 40.34% at flowering stage, 25.44% at fruit set stage and 13.92% at fruit ripening stage in winter crop season; 35.43% at flowering stage, 26.35% at fruit set stage and 14.21% at fruit ripening stage in rainy crop season. Major feeding groups of omnivore and frugivore species were noted during the fruit ripening stage of both seasons. During rainy crop season, nine bird species were observed feeding on insects. A statistical analysis of avian feeding guilds using the T-test revealed a significant difference in flowering and fruit ripening stages of guava crop seasons in the winter and rainy seasons.

Inoculation of raccoons with a wild-type-based recombinant canine distemper virus results in viremia, lymphopenia, fever, and widespread histological lesions.

Raccoons are naturally susceptible to canine distemper virus (CDV) infection and can be a potential source of spill-over events. CDV is a highly contagious morbillivirus that infects multiple species of carnivores and omnivores, resulting in severe and often fatal disease. Here, we used a recombinant CDV (rCDV) based on a full-genome sequence detected in a naturally infected raccoon to perform pathogenesis studies in raccoons. Five raccoons were inoculated intratracheally with a recombinant virus engineered to express a fluorescent reporter protein, and extensive virological, serological, histological, and immunohistochemical assessments were performed at different time points post inoculation. rCDV-infected white blood cells were detected as early as 4 days post inoculation (dpi). Raccoon necropsies at 6 and 8 dpi revealed replication in the lymphoid tissues, preceding spread into peripheral tissues observed during necropsies at 21 dpi. Whereas lymphocytes, and to a lesser extent myeloid cells, were the main target cells of CDV at early time points, CDV additionally targeted epithelia at 21 dpi. At this later time point, CDV-infected cells were observed throughout the host. We observed lymphopenia and lymphocyte depletion from lymphoid tissues after CDV infection, in the absence of detectable CDV neutralizing antibodies and an impaired ability to clear CDV, indicating that the animals were severely immunosuppressed. The use of a wild-type-based recombinant virus in a natural host species infection study allowed systematic and sensitive assessment of antigen detection by immunohistochemistry, enabling further comparative pathology studies of CDV infection in different species. IMPORTANCE Expansion of the human interface supports increased interactions between humans and peridomestic species like raccoons. Raccoons are highly susceptible to canine distemper virus (CDV) and are considered an important target species. Spill-over events are increasingly likely, potentially resulting in fatal CDV infections in domestic and free ranging carnivores. CDV also poses a threat for (non-human) primates, as massive outbreaks in macaque colonies were reported. CDV pathogenesis was studied by experimental inoculation of several species, but pathogenesis in raccoons was not properly studied. Recently, we generated a recombinant virus based on a full-genome sequence detected in a naturally infected raccoon. Here, we studied CDV pathogenesis in its natural host species and show that distemper completely overwhelms the immune system and spreads to virtually all tissues, including the central nervous system. Despite this, raccoons survived up to 21 d post inoculation with long-term shedding, supporting an important role of raccoons as host species for CDV.

Dietary Niche of Three Omnivorous Turtle Species in a Northern Florida River: Insights from Stable Isotope Analysis

Macrochelys suwanniensis (Suwannee Alligator Snapping Turtle) coexists with 2 other native large omnivorous turtle species (Chelydra serpentina [Snapping Turtle] and Trachemys scripta scripta [Yellow-bellied Slider]) in a 9-km section of the Santa Fe River in northern Florida. A major shift in dominant submersed aquatic vegetation prompted us to quantify trophic position and niche overlap among these 3 species. Here, we examine carbon and nitrogen isotopic values of these turtles and their potential food resources within the changing riverine system. We provide evidence of low isotopic niche overlap between M. suwanniensis and C. serpentina, whereas T. s. scripta occupied a discrete niche having lower carbon and nitrogen values.