Taxa Richness Research Articles

Living on the edge: Predicting invertebrate richness and rarity in disturbance‐prone aquatic–terrestrial ecosystems

Abstract Temporal fluctuations in cause the spatial extent of wet and dry habitats to vary in aquatic–terrestrial riverine ecosystems, complicating their biomonitoring. As such, biomonitoring efforts may fail to characterize the species that inhabit such habitats, hampering assessments of their biodiversity and implementation of evidence‐informed management strategies. Relationships between the dynamic characteristics of aquatic–terrestrial habitats and their communities are well known. Thus, habitat characteristics may enable estimation of faunal assemblage characteristics such as taxonomic richness, regardless of in‐channel water levels. We investigated whether indicators summarizing habitat survey data can predict two metrics representing terrestrial invertebrate assemblages (e.g. taxa richness) in two aquatic–terrestrial habitats: exposed riverine sediments and dry temporary streams. We also compared the performance of unimetric and multimetric habitat indicators in making predictions. In exposed riverine sediments, >88% of predictions were correlated with observed taxa richness and an index of conservation status. Values predicted by exposed riverine sediment samples were correlated with those observed in temporary stream channels with comparable riparian (i.e. largely agricultural) land use, but not those observed in channels with contrasting (i.e. more urban) land use. Unimetric habitat indicators performed similarly to more complex multimetric indicators, with each explaining ≤6% of the variability in taxa richness and the index of conservation status. The different spatial scales at which invertebrates respond to habitat conditions and at which indicators record habitat conditions, and a more comprehensive training dataset that incorporates a full range of habitat conditions (i.e. land use), may improve future predictions. We demonstrate that invertebrate assemblage characteristics can be predicted regardless of in‐channel water levels. Agreement between exposed riverine sediment predictions and temporary stream observations suggests that these predictions are transferable among a range of aquatic–terrestrial habitat types, and could thus be widely applied to aid conservation of riverine biodiversity in dynamic aquatic–terrestrial ecosystems.

Influencia de las prácticas agrícolas en los ensambles de macroinvertebrados en la Patagonia (Argentina)

Aquatic species in agricultural areas are often exposed to concentrations of pesticides and fertilizers that can affect the entire community. This study aimed to monitor the presence of nutrients and pesticides (organophosphates and carbamates) and evaluate their effects on the composition of macroinvertebrate assemblages at two sites in the Neuquén River, both upstream (UNR) and downstream (DNR) of an area of intensive cultivation of pome fruit trees. Physicochemical parameters in water samples from UNR and DNR were not significantly different, except for nitrate (NO3-). Pesticides analyzed were below detection limits in water and sediment samples. Insects constituted 52.76% of the total individuals in UNR and, among them, Ephemeroptera was the most abundant taxon (n=419). On the other hand, 67.67% of the individuals in DNR were insects, and most of them belonged to the Order Diptera (n=1156). The abundance of Diptera and Ephemeroptera individuals was significantly different between sites. In addition, the temporal variation of richness within each site showed significant differences (P<0.05). There were 15 shared species and a Jaccard’s abundance-based index indicated 37.8% taxonomic similarity. In summary, there were no significant differences in abundance and diversity between UNR and DNR. However, there were differences in taxa richness and composition, with a low percentage of similarity between sites. The above can be observed in the canonical correspondence analysis, which shows a clear relationship between environmental variables and the distribution pattern of macroinvertebrate assemblages.

Effects of Hydrologic Pulsing and Vegetation on Invertebrate Communities in Wetlands

Constructed, mitigation wetlands in the midwestern United States are frequently dominated by a Typha spp. monoculture and their hydrologies are often determined by adjustable control structures. Wetlands provide habitat for multiple macroinvertebrate species, which in turn provide food for other organisms inhabiting the wetlands, such as waterfowl. This study examined the impacts of plant diversity and manipulated hydrology on macroinvertebrate communities. Forty 1-m2 wetland mesocosms were either planted with a monoculture of Typha spp. or with a more diverse plant community of Schoenoplectus tabernaemontani, Juncus effusus, and Sparganium eurycarpum. They were also assigned to one of four hydrologic regimes: steady state, pulsing, deep spring/shallow fall, and shallow spring/deep summer. After one year, macroinvertebrates were sampled in the mesocosms. Mesocosms with deep spring hydrologies were found to have greater taxon diversity than those with other hydrologies, but Chironomidae biomass was the lowest under the deep spring hydrology. Culicidae and Chironomidae were found in higher numbers in mixed vegetation than in Typha spp. Taxon richness and Chironomid biomass were significantly higher in mixed vegetation mesocosms than in Typha spp. monocultures. Results suggest vegetation diversity and hydrological regimes impact macroinvertebrate communities, with potential implications for constructed wetland design and management.

Unravelling the environmental correlates influencing the seasonal biodiversity of aquatic Heteropteran assemblages in northern Africa

Heteropteran communities form a key component of aquatic ecosystems but have not been widely studied compared to other freshwater faunal groups. This research examined the environmental parameters influencing the diversity, seasonal distribution and structure of aquatic Heteroptera assemblages in the Mediterranean region of Tunisia, northern Africa. Heteropterans were most abundant during spring and summer, coinciding with the emergence of several species and the most favorable environmental conditions for benthic aquatic fauna. Three-way multivariate analyses (combining community composition data from all sites and seasons) highlighted the longitudinal spatial organization of Heteropteran communities. Headwater regions were dominated by halophobic sensitive taxa, and lowland sites were characterized by high salinity resistant taxa (halophilic taxa). The longitudinal organization was driven by gradients of mineralization (salinity and electrical conductivity) and oxygen (DO, COD and BOD) concentrations. Taxonomic composition differed between river catchments, with significantly higher diversity (taxa richness) in the streams with adjacent riparian forest cover. These sites were characterized by the presence of endemic species, such as Velia africana and Velia eckerleini, and rare species, Notonecta meridionalis, and Aquarius najas. Results recorded highlight the importance of aquatic vegetation and water quality in driving the seasonal and spatial variability of Heteropterans, and provide important information to inform the management and conservation of freshwater biodiversity in Northern Africa.

Diversity and Typology of Land-Use Explain the Occurrence of Alien Plants in a Protected Area.

Plant life history and functional characteristics play an important role in determining the invasive potential of plant species and have implications for management approaches. We studied the distribution of 24 alien plant taxa in a protected area in relation to different land-uses by applying ordination analyses and generalized linear models. Taxa richness is best explained by the presence of built-up areas, followed by residential areas, marshlands, and agricultural lands with semi-natural formations. The diversity of land-use within the grid cell proved to be an important explanatory factor, being the only significant variable explaining the richness of wood perennials and vines. The richness of annual herbs and seed-dispersed taxa is explained by a similar set of variables, with the exception of residential areas. The richness of invasive species is explained only by agricultural land and the diversity of land-use. The richness of taxa with predominant vegetative dispersal is best explained by built-up, marshland, and seminatural areas along with land-use diversity. When we consider only the presence of plant groups within grid cells, the results are similar. The results of similar studies may provide an important tool for defining sustainable practices and overall conservation management in protected areas.

Meta-analysis of ecosystem services associated with oyster restoration.

Restoration of foundation species promises to reverse environmental degradation and return lost ecosystem services, but a lack of standardized evaluation across projects limits understanding of recovery, especially in marine systems. Oyster reefs are restored to reverse massive global declines and reclaim valuable ecosystem services, but the success of these projects has not been systematically and comprehensively quantified. We synthesized data on ecosystem services associated with oyster restoration from 245 pairs of restored and degraded reefs and 136 pairs of restored and reference reefs across 3500km of U.S. Gulf of Mexico and Atlantic coastlines. On average, restoration was associated with a 21-fold increase in oyster production (mean log response ratio=3.08 [95% confidence interval: 2.58-3.58]), 34-97% enhancement of habitat provisioning (mean community abundance=0.51 [0.41-0.61], mean richness=0.29 [0.19-0.39], and mean biomass=0.69 [0.39-0.99]), 54% more nitrogen removal (mean=0.43 [0.13-0.73]), and 89-95% greater sediment nutrients (mean=0.67 [0.27-1.07]) and organic matter (mean=0.64 [0.44-0.84]) relative to degraded habitats. Moreover, restored reefs matched reference reefs for these ecosystem services. Our results support the continued and expanded use of oyster restoration to enhance ecosystem services of degraded coastal systems and match many functions provided by reference reefs.

Landscape and age dynamics of immune cells in the Egyptian rousette bat.

Bats harbor high-impact zoonotic viruses often in the absence of disease manifestation. This restriction and disease tolerance possibly rely on specific immunological features. In-depth molecular characterization of cellular immunity and imprinting of age on leukocyte compartments remained unexplored in bats. We employ single-cell RNA sequencing (scRNA-seq) and establish immunostaining panels to characterize the immune cell landscape in juvenile, subadult, and adult Egyptian rousette bats (ERBs). Transcriptomic and flow cytometry data reveal conserved subsets and substantial enrichments of CD79a+ B cells and CD11b+ Tcells in juvenile animals, whereas neutrophils, CD206+ myeloid cells, and CD3+ Tcells dominate as bats reach adulthood. Despite differing frequencies, phagocytosis of circulating and tissue-resident myeloid cells and proliferation of peripheral and splenic lymphocytes are analogous in juvenile and adult ERBs. We provide a comprehensive map of the immune landscape in ERBs and show age-imprinted resilience progression and find that variability in cellular immunity only partly recapitulates mammalian archetypes.

Patterns of species richness, abundance and individual-size distributions in native stream-fish assemblages invaded by exotic and translocated fishes.

Predicting the impacts of species introductions long has attracted the attention of ecologists yet there still is limited insight into how impacts on native assemblages vary with the degree of shared evolutionary context. Here, we used data from 535 stream-fish surveys from 15 catchments in north-eastern Spain (99,700 km2) to explore whether the relative effects on native fishes differ between fish introductions from two different ecoregions (i.e., evolutionary contexts), namely, catchments within Iberian Peninsula (i.e., 'translocated species') and catchments beyond Iberian Peninsula (i.e., 'exotic fishes'). We used hierarchical Bayesian models to relate taxon richness, abundance, and the individual-size distributions (ISDs) of native fishes to the presence, abundance, and weighted trophic level (TL) of translocated and exotic fishes, conditional on geographic and habitat covariates. Environmental covariates dominated the percentage of explained variance (≥ 65%) for all responses. Translocated fishes accounted for more of the explained variance than did exotic fishes for ISDs and abundance, but not for native fish species richness. The presence of translocated fishes was associated with lower abundance and richness of native fishes, with individuals being smaller in the presence of translocated fishes of higher TL. The presence of exotic fishes was associated with a greater abundance and richness of native fishes, with individuals generally being larger in the presence of exotic fishes. Our study suggests that translocated fishes could be as problematic as exotic fishes when angling and water transfers among catchments to deal with climate change may increase the establishment of translocated fishes. We also discuss the difficulties of using fish body size as species-blind, transferable assemblage-level trait in fish monitoring.

Variability at multiple spatial scales in intertidal and subtidal macrobenthic communities in a fjord with glaciers, Magellanic Subantarctic ecoregion, Chile

It has been observed in high-latitude marine environments of the Southern Hemisphere that the variability in the ecological patterns of macrobenthic communities show variations at different spatial scales (i.e. cm to km), mainly influenced by environmental stress gradients. We examined macrobenthic communities of intertidal and subtidal habitats in a glacial fjord using taxonomic, ecological and oceanographic approaches, estimating vertical and horizontal variation using a nested design with different spatial scales ranging from centimeters to kilometers (quadrats, patches, shore and sites respectively). We found that vertical patterns in taxon richness and community structure were significant in both habitats. These patterns also showed horizontal variability at different spatial scales, becoming more pronounced at smaller scales (quadrats). The dominant taxa in the intertidal (macroalga) and subtidal (macroinvertebrate) communities also exhibited a scale-dependent distribution pattern, indicating that the greatest horizontal variation occurs at small spatial scales. Annual and opportunistic green algae such as Ulva intestinalis and Cladophora flexuosa were dominant in the intertidal, while the dominant taxa in the subtidal were the filter-feeding bivalve Aulacomya atra and the suspensivorous hydrozoan Symplectoscyphus marionensis. The results were related to biological interactions and local abiotic factors characteristic of an estuarine system influenced by glaciers, with lower salinity and temperature and higher turbidity in sites close to glaciers. The information generated on diversity patterns is very relevant and can serve as a baseline in the evaluation of ecological patterns of shallow macrobenthic communities in environmental gradients influenced by glaciers in the Magellanic Subantarctic ecoregion.

Distribution of benthic macroinvertebrates in relation to physicochemical parameters and macrophyte cover in the Ketar River, Ethiopia

The aim of this study was to determine the effects of physicochemical parameters and macrophyte on the macroinvertebrate assemblages in the Ketar River, which drains into Lake Ziway. Six sampling sites were selected along the river stretch and samples were collected from December to April 2017/2018 based on the method outlined in Ontario Benthos Biomonitoring Network Protocol Manual. A total of 5,450 individuals comprised of one class, 7 orders, and 23 families were collected during the study period. Hemiptera families were the predominant taxa and contributed the largest percentage of the total samples followed by the Coleoptera. Notonectidae and Corixidae shared the highest total abundance. This study confirmed that the sites covered with macrophytes were significantly different from the substrate both in taxa richness and total abundance (P < 0.05). Redundancy Analysis revealed that pH, Temperature, electric conductivity, DO, NO2, NO3, NH4, SiO2 and TP were the most important variables explaining the variation in macroinvertebrate assemblage patterns. The mean Shannon diversity index also indicated that the sites covered by the macrophyte stand had a significantly higher value than the sites sampled from the substrate, which implies that macrophytes support abundant, and promoting the diversity of macroinvertebrates. Thus, the conservation of macrophytes can enhance the conservation of macroinvertebrates along the course of the river, besides the role of macrophyte in sediment trapping and reducing sedimentation buildup in Lake Ziway.

Bottom‐up effects of plant quantity and quality on arthropod diversity across multiple trophic levels in a semi‐arid grassland

Abstract Plant quantity and quality can independently affect the diversity of the entire arthropod communities and multiple arthropod taxa in grassland ecosystems. However, it remains unclear how these effects on arthropod taxa at one trophic level propagate through food web to influence the diversity of higher trophic levels. We performed a monoculture experiment with 15 herbaceous species in the Inner Mongolian grassland to investigate how natural variations in plant productivity and host leaf traits affect herbivore taxon richness, which, in turn, affects predator taxon richness. For herbivores, plant productivity indirectly promoted herbivore taxon richness by increasing herbivore biomass, which was attributed to the increases in the richness of dominant sucking herbivores and endophytes with high food requirements. However, the high plant quality indicator (e.g. high leaf protein, phosphorus and water contents, and high leaf protein to carbohydrate ratio) directly increased, whereas the low plant quality indicator (e.g. high leaf lignin content) directly decreased herbivore taxon richness. Taxon richness of chewing and sucking herbivores with specific feeding modes (tearing or sucking mouthparts) showed strong positive responses to increasing plant quality. For predators, herbivore taxon richness, rather than herbivore biomass, mainly mediated the positive effects of plant productivity and the high plant quality indicator, but the negative effect of the low plant quality indicator, on predator taxon richness. At the feeding guild level, the taxon richness of parasitoids, other predators and spiders exhibited positive responses to different herbivores, which was attributed to their different diet preferences. Predator diversity could be promoted by prey partitioning among predator guilds facilitating species coexistence. At the family level, the taxon richness of most predator families was positively correlated with that of more than one herbivore family, suggesting that high predator diversity may be caused by balanced diets owing to high prey diversity. Synthesis. Natural variations in plant quantity and quality can substantially affect the diversity of herbivores and cascade up the food web to affect predators. Specificity and mechanisms of feeding have a large impact on the responses of arthropod guilds at each trophic level.

Spatial occurrence and abundance of marine zooplankton in Northeast Greenland

We present a large-scale survey of mesozooplankton (size range 0.2–20 mm) across coastal, shelf, and slope locations in Northeast Greenland (latitudes 74–79° N, August 2015 and September 2017). Our study is centred on the Video Plankton Recorder (VPR) for non-invasive in situ observations of taxa distribution and abundance while simultaneously recording oceanographic profiles. A modified WP-2 plankton net (85-μm mesh size) was used primarily not only to verify taxa detected by the VPR but also to make a preliminary comparison of abundance estimates by the two gears. A total of 35 zooplankton taxa were identified with 10 genera alone among copepods (Hexanauplia). Selected taxa from the VPR (N=16) were associated with the temperature-salinity spaces and the chlorophyll a-depth profiles in the study area. From surface to > 900 m depth, the overall temperature and salinity ranged between −1.9 and 6.8 °C and 26.6 and 35.3, respectively. Two copepod genera dominated, i.e. Pseudocalanus prevailed in the upper sub-zero layers in coastal waters whereas Calanus was omnipresent, but mainly abundant in the warmer Atlantic waters at the shelf break. Chlorophyll a levels were in general very low (< 2 mg m-3) and peaked at 30–50 m depth, suggesting post-bloom conditions. Overall, zooplankton abundances tended to increase from the coast towards the slope (9–344×103 individuals m-2). Biodiversity in terms of taxon richness, on the other hand, showed the opposite trend and decreased from 16 taxa at the coast to 5 taxa further offshore.

Spatio-temporal Effects of Anthropogenic Disturbances on Macroinvertebrates in Subukia River, Kenya

Anthropogenic disturbances modify river habitat conditions and influence the distribution of biotic communities. However, the effect of anthropogenic disturbances on macroinvertebrates is unknown for the Subukia River, despite its importance as a source of water for the local people and a habitat for organisms. This study was conducted to evaluate the effect of study site locality and seasonal variability on macroinvertebrate characteristics in the Subukia River. Nine study sites were chosen to correspond with livestock watering and human activities such as laundry washing, water abstraction, cultivation, dumping of solid wastes, settlements along the riparian zone and clearance of riparian vegetation. Mean invertebrate abundance, Shannon-Wiener diversity index, a Multimetric index, Taxa richness, Ephemeroptera, Plecoptera, Trichoptera (EPT) abundance and richness and Dominance index were determined. The results of the study showed that study site locality had a significant effect on Taxa richness (p=0.003), EPT abundance (p = 0.003) and richness (p=0.02), Shannon-Wiener diversity (p=0.003) and Multimetric index (p=0.003). Seasonal variability only had a significant effect on Taxa richness (p=0.01). In conclusion, most macroinvertebrate characteristics are influenced by anthropogenic disturbances and are less influenced by seasonal variability.

Drying niches of aquatic macroinvertebrates identify potential biomonitoring indicators in intermittent and ephemeral streams

Intermittent rivers and ephemeral streams (IRES) compose the majority of draining networks on Earth, supporting a unique fraction of biodiversity. Despite their high ecological value, IRES are increasingly threatened by global change and require appropriate biomonitoring and restoration tools. However, indices and indicators used in routine biomonitoring programs are often confounded by drying effects. This occurs because most pollution-sensitive taxa are lost over drying gradients, limiting the utility of current biomonitoring tools in IRES. To address this challenge, there is a need to evaluate which taxa should be used to calculate biomonitoring metrics and indicators over the different portions of the drying gradient. Here, using high-resolution drying data from 33 unpolluted streams, we explored the drying preferences of macroinvertebrates to identify their potential as biomonitoring indicators in IRES. To do this, we characterized macroinvertebrate drying niches and identified those with drying resistance and sensitivity preferences. Next, we evaluated the capacity of functional traits to predict drying specialization and affinity. Finally, to identify potential biomonitoring metrics and indicators for IRES, we evaluated how drying influenced the density, relative abundance and richness of taxa in drying-sensitive and drying-resistant niches. Our results identified three macroinvertebrate groups with drying-resistant niches (partly tolerant, generalist and specialist taxa) and one group of drying-sensitive taxa. We also found that functional traits had a limited capacity to represent differences in drying niches, with shredding trophic preferences and body size showing the strongest correlations. In addition, we observed that the density, relative abundance and richness of drying-resistant taxa were less influenced by drying intensity than those of drying-sensitive taxa. Finally, we found that some pollution-sensitive taxa with partial (e.g., Lepidostoma), moderate (e.g., Corduliidae) or high drying tolerance (e.g., Nemoura) can serve as potential indicators in IRES. Taken together, our results demonstrate that characterizing drying niches can be a useful strategy for developing biomonitoring tools in IRES and for highlighting the limitations of taxonomic and trait-based approaches.

Ganga River sediments of India predominate with aerobic and chemo-heterotrophic bacteria majorly engaged in the degradation of xenobiotic compounds.

Sediment provides a stagnant habitat to microbes that accumulate organic matter and other industrial pollutants from the upper layer of the water. The sediment of the Ganga River of India is overlooked for exploring the bacterial diversity despite their taxon richness over the water counterpart. To enrich the limited information on the bacterial diversity of the Ganga River sediment, the present study was planned that relies on amplicon-based bacterial diversity of the Ganga River sediment by using bacterial-specific 16S hypervariable region (V3-V4). The Illumina MiSeq2500 platform generated 1,769,226 raw reads from the metagenomes of various samples obtained from ten sites in five major cities of Uttar Pradesh and Uttarakhand regions traversing the Ganga River. Taxonomy level analysis assigned 58 phyla, 366 order, and 715 genera of bacterial type. The high values of various diversity indices (Chao1, Shannon, and Simpson) in Kanpur sediment indicate the high bacterial richness compared to the Rishikesh sediment. However, several other ecological parameters (Shannon index, Simpson index, enspie _vector, and Faith_pd) were comparatively higher in Rishikesh sediment which is a comparatively less disturbed region by human activities over the other sediments samples studied here. Ganga River sediment dominates with Gram-negative, chemo-heterotrophic, and aerobic bacteria that chiefly belong to Proteobacteria, Acidobacteria, Chloroflexi, and Bacteroidota. The abundance of Nitrospira, Hydrogenophaga, Thauera, Vicinamibacteraceae, and Latescibacterota in the Ganga River sediment could be considered as the ecological indicators that find a significant role in the degradation of xenobiotic compounds. The PICRUSt-based analysis showed that ~ 35% of genes were involved in benzoate and aminobenzoate degradation where a significant portion of genes belong to nitrotoluene degradation (14%). Thus, the study uncovers a new perspective in the lineage of bacterial communities and their functional characterization of the Ganga River sediment.

Maize varieties and their root trait variation mediate the development of rhizosphere arthropod diversity

While ecological roles of rhizosphere arthropods are well documented, little is known about the relationship between the development of plant roots and soil arthropod communities in agroecosystems. In this study, we investigated the effects of maize varieties and their root traits on the diversity and community composition of soil arthropods over time. Soil arthropods and root traits were evaluated before planting and at 30 and 60 days after planting in four maize varieties with different root growth angles and lateral root branching. Arthropod diversity declined from day 0 to 30 but recovered by day 60 with the development of maize roots. Two maize varieties (Nei 542018 and Nei 542022) exhibited lower brace and crown root angles, and arthropod taxon richness was greater in these two varieties than in others. The highest abundance of detritivores and predators was found in one of the maize varieties (Nei 542018) which, in addition to lower root angle, attained greater root diameter and lateral root branching and length. Redundancy analysis indicated that soil arthropod composition was correlated with crown root angle. Our findings highlight the importance of root traits, especially the angle of the roots, to enhance arthropod biodiversity in the rhizosphere ecosystem.

Anthropogenic induced physicochemical gradients and associated macroinvertebrate community changes in derived savannah stream in Nigeria: Implication for biotic assessment

Understanding the impact of anthropogenic activities on various ecosystem matrices is fundamental to the application of biotic assessment. Here we explored the spatial changes of macroinvertebrate community structure under varying physicochemical gradients in Adoka Stream at Eziani Town, Southeast Nigeria. The water and macroinvertebrate samples were obtained from three stations positioned along the stretch of the stream with station 1 taken as a reference to others. We adopted Principal Component Analysis (PCA) and Canonical Correspondence Analysis (CCA) to analyse the monitored dataset comprising of 16 parameters with the aim to identify the important physicochemical parameters, and further evaluated the relationship between physicochemical parameters and macroinvertebrates assemblages. The PCA in first two rotated components (RCs) showed that turbidity, EC, NO₃, PO₄, SO₄, Cl, BOD₅, COD, DO, pH, and HCO₃ explained 57% of variance in the water quality dataset and associated macroinvertebrates assemblage. Based on the CCA, temperature, pH, turbidity, EC, NO₃, SO₄, DO, HCO₃, Ca, and Mg were important to predicting changes of macroinvertebrates assemblage structure in the stream. The observed variations of the water quality were reflected on macroinvertebrate assemblage across the stations. High abundance, taxa richness and pollution sensitive taxa of Trichoptera were obtained for station 1 with good water quality while stations 2 and 3 with significant influence from anthropogenic activities which resulted to degrading water quality had low abundance and taxa richness as well as dominance of pollution-tolerant taxa of Diptera groups. Dolophilodes urceolus and Leptonema natalense were the dominant taxa of the trichopterans while individuals of taxa Chironomus transvaalensis, Paraphaenocladius sp., and Pentaneura nilotica dominated the dipterans. In conclusion, our results provided useful information that supports the protocol for biotic assessment and also baseline data on physicochemical conditions and macroinvertebrate composition of the stream.

The use of baited stygofauna traps as a complimentary sampling method for sampling groundwater bores in the Pilbara, Western Australia

Stygofauna sampling predominantly comprises active sampling methods, such as net hauling or hand netting, which although highly effective at collecting specimens, can cause significant specimen damage and is unlikely to collect vagrant species. Studies assessing the efficacy of using stygofauna traps (both baited and unbaited) have been conducted with varying levels of success. Thus, the development of a robust and effective stygofauna trap design may be advantageous. Between 2021 and 2022, in conjunction with Rio Tinto, Biologic began developing and trialling a stygofauna trap designed to sample groundwater bores or drill holes intersecting groundwater, with the aim of evaluating the following hypotheses: The stygofauna trap design and method used would successfully collect stygofauna in groundwater bores and drill holes intersecting groundwater. Some taxa collected in stygofauna traps may differ from those collected in net haul samples, due to differences in ecological habit of fauna (crawling taxa colonising traps) or vagrant stygofauna (fauna travelling between suitable habitats). Specimens collected in traps will be in better condition than those collected in net haul samples. This has positive implications for taxonomic and molecular identification, as well as the collection of voucher specimens. The stygofauna trap design and method used would successfully collect stygofauna in groundwater bores and drill holes intersecting groundwater. Some taxa collected in stygofauna traps may differ from those collected in net haul samples, due to differences in ecological habit of fauna (crawling taxa colonising traps) or vagrant stygofauna (fauna travelling between suitable habitats). Specimens collected in traps will be in better condition than those collected in net haul samples. This has positive implications for taxonomic and molecular identification, as well as the collection of voucher specimens. Based on a fish funnel or box trap, the stygofauna traps consist of a 90mm cylindrical PVC frame, with a 150µm mesh inner lining. Both ends of the trap are capped with a removable funnel, allowing fauna to enter. In September 2021, a preliminary trial was conducted on sites intersecting the Robe and Bungaroo aquifers, in the coastal Pilbara region of Western Australia. These shallow aquifers are characterised by a highly abundant and rich stygofauna assemblage, typically dominated by crustaceans. Stygofauna traps (one trap per site) were deployed in seven groundwater bores or drill holes intersecting groundwater. The traps, baited with algae pellets, were set at the bottom of the bore, and collected between 12 and 24 hours of deployment. For comparison, net haul sampling was conducted at each site immediately prior to trap deployment. Results from the initial trial were promising, prompting a two season (wet and dry) study. This study commenced in March 2022, where traps were deployed in 11 sites across both aquifers. Two baited traps per site were deployed, one within 1m of the groundwater level and one at the end of the hole, for 72 hours, to determine if a longer deployment and an additional trap would yield better results. The final phase of sampling is planned for August 2022. Results from both the preliminary trial and first (wet) season of the 2022 study were very promising, with stygobitic taxa collected in four (of the seven) and nine (of eleven) trap sites respectively. The traps recorded a rich assemblage of stygofauna comprising Amphipoda, Copepoda, Gastropoda, Isopoda, Ostracoda and Thermosbaenacea. Compared to the respective net haul samples, the stygofauna traps yielded lower abundances and taxa richness. However, specimens collected in traps were in excellent morphological condition. At the conclusion of this study, taxonomic composition and abundance of stygofauna from the traps and net hauls will be analysed to provide further contextualisation of results.

How invasive macrophytes affect macroinvertebrate assemblages and sampling efficiency: Results from a multinational survey

Macrophytes play an important role in the functioning and structuring of aquatic environments but rapid mass development of invasive macrophytes is causing global concerns. Macroinvertebrate richness and abundance are strongly influenced by macrophytes as macrophytes offer habitats and food resources, increase structural heterogeneity, and provide refuges. Meanwhile, the presence of macrophytes affects the efficiency of standard sampling methods for macroinvertebrates. These effects are not well studied but are leading to biased management decisions. To fill in this knowledge gap, we analysed macroinvertebrate communities from four lakes in four countries in Europe and Africa with mass development of invasive macrophytes. We compared macroinvertebrate communities in sediment samples from a plant-free part of the lake with those in sediment and sweep samples taken within macrophyte stands. We showed that taxa richness and density were higher in sediment samples beneath invasive macrophyte stands compared to plant-free habitats. Unique taxa were found in each sample type. Sampling efficiency of each sampling method varies greatly across lakes especially when replication is low. The taxonomic richness of macroinvertebrates within invasive macrophyte stands is often underestimated compared to open water sections with the same number of samples. To reach a high sampling coverage, a higher number of samples is necessary for sampling within invasive macrophytes. Our findings call for the development of a method that allows for comparable sampling within and outside of macrophyte stands. Such method will be the foundation for future research and management of aquatic systems.

Assessing the Diet of a Predator Using a DNA Metabarcoding Approach

The diet of top predators is vital information needed to determine their ecological function and for their conservation management. However, the elusive habit and low population density of many predators constrains determination of their diets. While the morphological identification of scat contents is the traditional method, DNA metabarcoding has lately proven a more efficient and accurate method of identifying prey taxa. We applied DNA metabarcoding to analyzing the diet of the Eurasian otter (Lutra lutra), a top predator in freshwater ecosystems, using 12S and 16S rRNA mitochondrial primers target vertebrate prey. Diet did not vary among different data removal thresholds of 0.1, 1, 3, and 5%, comprising fishes (&amp;gt;90%), amphibians and birds (&amp;gt;2%), and occasionally mammals (&amp;lt;2%). Both 12S and 16S primers revealed similar otter diets, indicating that a single set of primers with a higher threshold is cost-effective for detecting the main prey taxa. Using 12S primers and a 5% threshold, we found no seasonal variation of otter diet in the Tangjiahe National Nature Reserve. A different prey community was found outside the reserve, which resulted in different prey composition for otters. However, prey taxon richness was not different between otters in- and outside the reserve. Otters preferred Schizothorax spp., the largest-sized fish species in the reserve, whereas they mainly preyed on Triplophysa bleekeri, a small-sized fish species, outside the reserve. Otters’ flexible feeding strategy reflect their high adaptability. However, greater human disturbance outside the reserve may present significant challenges to otters by altering prey communities and reducing prey profitability. Combining fecal DNA metabarcoding and local fish survey will provide opportunities for more detailed studies on the impact of different levels of human disturbances on prey communities and otters.