Macroinvertebrate Taxa Research Articles

Adaption of a traditional Māori fishing method for biomonitoring: using whakaweku for sampling benthic macroinvertebrates in streams

ABSTRACT Whakaweku are bundles of bracken fern (Pteridium esculentum) traditionally placed in lakes and rivers by Māori to harvest kōura (freshwater crayfish, Paranephrops spp.) in Aotearoa, New Zealand. Previous studies show they are effective for monitoring populations of kōura and toitoi (small eleotrid fish, Gobiomorphus spp.). We wanted to determine whether whakaweku are also effective for monitoring benthic macroinvertebrate communities in streams. We placed whakaweku in a hard-bottomed and a soft-bottomed reach of a rural stream in the Waikato, and took standard ‘kick-net’ samples from the same locations. We retrieved whakaweku after two and four weeks submerged. Whakaweku gave comparable results to kick-net sampling for common macroinvertebrate metrics (MCI, SQMCI, total richness and EPT* richness). Macroinvertebrate community composition was significantly different between the two methods, but most taxa were common to both. Macroinvertebrate metrics did not change significantly between two-week and four-week colonisation periods. A wider study would show whether whakaweku can distinguish between sites over a gradient of human impact. We recommend whakaweku in Māori cultural and community stream monitoring as it is inexpensive, simple to use, captures many macroinvertebrate taxa used in biomonitoring, works in different stream types and can be used to monitor kōura, toitoi and macroinvertebrates simultaneously.

Aquatic invertebrate diversity in Apostle Islands and Isle Royale waters: Comparison among habitats and sampling gears and to open Lake Superior

Aquatic invertebrate composition in Great Lakes nearshore regions is known to differ from offshore, but studies representing the closest-to-land end of this gradient are primarily from estuaries and rivermouths having substantial watershed connectivity and anthropogenic influence. Here, we present data from aquatic invertebrate surveys conducted in two Lake Superior parks that are distanced from such watersheds and pressures, namely Apostle Islands National Lakeshore (APIS) and Isle Royale National Park (ISRO). Our intensive, multi-gear surveys from 99 APIS stations in 2017 and 165 ISRO stations in 2012 reveal a broad diversity of zooplankton and benthic/littoral macroinvertebrate taxa. Park samples yielded 29 zooplankton and >300 benthic/littoral taxa, with richness exceeding that of comparable nearshore datasets, especially for aquatic insects, leeches, and mites. Station depth was a major factor structuring invertebrates, and benthic/littoral densities were highest and composition most diverse at shallow stations having aquatic vegetation. Species composition and taxa accumulation patterns differed considerably among sampling gears, highlighting the value of multi-gear surveys. Several park mollusk and insect species matched ‘special concern’ listings, and two non-native cladocerans were very abundant. These two surveys added 11 new species to the aquatic macroinvertebrates known from Lake Superior, highlighting the importance of these parks in harboring biodiversity and the importance of individualized assessments of places not well represented in more routine lakewide biological monitoring. Our data are available as baselines for future biological surveys and trend assessments.

Micro‐ and nano‐plastic loads in fish and macroinvertebrates in a tropical river

Abstract This study examines microplastic contamination in river macroinvertebrates and fish within a rapidly urbanising tropical catchment, and provides data on the quantity of microplastics ingested by various taxonomic and functional feeding groups. We employed both a widely used low‐resolution visual inspection method, capable of identifying microplastics ranging from 0.1 to 5 mm, and a novel automated method specifically designed to identify smaller plastics in the nano size range, from 0.004 to 0.1 mm. Analysis using the low‐resolution method indicated that a significant portion of fish (95%) and macroinvertebrates (44%) contained larger microplastics. The composition of microplastic within the animals differed from that in river water and on the river bed: microplastics in the water and on the bed were predominantly fibres (98% and 92% respectively), whereas the animals exhibited a more even mix of fibres (c. 35%), fragments (c. 43%), and film (c. 22%). Microplastic loads in aquatic organisms correlated with feeding group and body size, although patterns were not always consistent. Larger individuals generally contained more microplastic, especially among macroinvertebrates, but this trend was not observed uniformly among fish species. Additionally, differences in body loads among macroinvertebrate taxa and feeding groups varied depending on whether loads were expressed per individual or per unit weight. Use of the high‐resolution enumeration method revealed a substantially higher microplastic count compared to the low‐resolution method, highlighting the potential underestimation of contamination levels by the latter. The study underscores the non‐random uptake of microplastics by aquatic biota, influenced by feeding mode, and stresses the necessity of high‐resolution sample processing for accurate quantification of contamination levels and risk assessment for smaller organisms.

Fish and macroinvertebrates respond differently to seasonal drying in tropical non‐perennial streams

AbstractSurface water drying challenges the persistence of lotic biological assemblages in non‐perennial streams and rivers. However, the effects of natural hydrological disturbances on an assemblage depend on individual species characteristics. In this study, we investigated the structure and association of fish and macroinvertebrate assemblages during two phases in non‐perennial streams (flowing vs. disconnected pools). We sampled fish and macroinvertebrate assemblages in five non‐perennial stream reaches located in the Caatinga (Brazilian semi‐arid region). Fish species were resistant to hydrological dynamics in the streams. On the other hand, some macroinvertebrate taxa from the flowing phase disappeared, and new taxa colonized the disconnected pools. The absence of lotic insects following flow cessation and the colonization of disconnected pools by lentic taxa facilitated macroinvertebrate assemblages persistence in these dynamic streams. Our study showed that fish and macroinvertebrate assemblages respond differently to the same natural flow cessation, which leads us to predict that flow changes will yield different assemblages, depending on the taxa. Thus, it is crucial to consider multi‐assemblage responses to effectively manage and conserve non‐perennial stream ecosystems in a tropical semi‐arid region.

Improved thermal preferences and a stressor index derived from modeled stream temperatures and regional taxonomic standards for freshwater macroinvertebrates of the Pacific Northwest, USA

Benthic macroinvertebrate taxa vary in their sensitivities to water quality and habitat conditions, contributing to their extensive use as ecological indicators. As climate change and landscape alteration increasingly impact stream temperatures, interest is growing in expanding our knowledge of how macroinvertebrates are affected by current and future thermal conditions. Using samples from 3501 sites, we evaluated relationships between macroinvertebrate taxa and modeled stream temperatures across Oregon and Washington, in the U.S. Pacific Northwest. We used Maximum Weekly Maximum Temperature (MWMT) values from the NorWeST temperature dataset, which is the same metric used for numeric water temperature standards in Oregon and Washington. MWMT captures peak thermal stress, when cold-water adapted aquatic biota are closest to their upper physiological limits. For each macroinvertebrate taxon, we characterized relationships between MWMT and their distributions with three measures: 1) central thermal tendency, based on weighted average (WA) optima calculations and relative abundance data; 2) lower and upper thermal limits, based on the 10th and 90th percentiles of taxon occurrence, using presence data; and 3) thermal sensitivity curve shape, based on Generalized Additive Model (GAM) plots. We assigned 521 taxa, from species to phyla, to seven thermal preference categories, ranging from cold and warm stenotherms (narrow range) to eurythermal (wide range). Thermal sensitivity and variability within each taxonomic group were identified for establishing taxonomic targets for regional monitoring programs. We also developed the Macroinvertebrate Thermal Tolerance Index (MTTI) to represent the assemblage-level response to available thermal habitats, using WA optima and relative abundances for 324 taxa. The MTTI model had a strong relationship with modeled temperatures (R2 = 0.68) and a root-mean-square-error of 2.5 °C. Our work builds on previous regional and national efforts to identify thermal indicator taxa by using modeled stream network temperatures and a thermal metric that corresponds directly to regional water temperature standards. Both the taxa thermal preferences and the MTTI can be used to help identify causes of biological impairment, prioritize restoration and protection actions, and monitor assemblage-wide changes in thermal tolerance over time.

Nuanced impacts of the invasive aquatic plant Crassula helmsii on Northwest European freshwater macroinvertebrate assemblages

Invasive alien species are considered one of the greatest threats to global biodiversity, and are particularly problematic in aquatic systems. Given the foundational role of macrophytes in most freshwaters, alien aquatic plant invasions may drive strong bottom-up impacts on recipient biota. Crassula helmsii (New Zealand pygmyweed) is an Australasian macrophyte, now widespread in northwest Europe. Crassula helmsii rapidly invades small lentic waterbodies, where it is generally considered a serious threat to native biodiversity. The precise ecological impacts of this invasion remain poorly understood, however, particularly with respect to macroinvertebrates, which comprise the bulk of freshwater faunal biodiversity. We conducted a field study of ponds, ditches and small lakes across the core of C. helmsii's invasive range (United Kingdom, Belgium and the Netherlands), finding that invaded sites had higher macroinvertebrate taxon richness than uninvaded sites, and that many infrequent and rare macroinvertebrates co-occurred with C. helmsii. Alien macroinvertebrates were more abundant in C. helmsii sites, however, particularly the North American amphipod Crangonyx pseudogracilis. At the order level, water beetle (Coleoptera) richness and abundance were higher in C. helmsii sites, whereas true fly (Diptera) abundance was higher in uninvaded sites. Taxonomic and functional assemblage composition were both impacted by invasion, largely in relation to taxa and traits associated with detritivory, suggesting that the impacts of C. helmsii on macroinvertebrates are partly mediated by the availability and palatability of its detritus. The nuanced effects of C. helmsii on macroinvertebrates found here should encourage further quantitative research on the impacts of this invasive plant, and perhaps prompt a more balanced re-evaluation of its effects on native aquatic macrofauna.

Diatom and macroinvertebrate communities dynamic: A co-occurrence pattern analysis on plastic substrates

Wetlands are habitats that provide numerous ecosystem services, but are often understudied and threatened by anthropogenic pollution, particularly plastic pollution. Macroplastics are a significant component of plastic litter that have high biological impacts but are often understudied. Previous studies have highlighted negative impacts on biota, but there is a lack of information about the communities of micro and macro organisms that settle on macroplastic litter. In this context, we investigated the colonization patterns and community structures of diatoms and macroinvertebrates on virgin substrates composed of two different plastic polymers, polystyrene and polyethylene terephthalate, located at two different depths in a protected wetland in Central Italy over a period of 10 months. The results show that diatom community is not highly structured by competitive forces and aggregation patterns emerges. In contrast, macroinvertebrate community appears to be randomly structured, without the presence of patterns following specific assembly rules. Randomness in macroinvertebrates assemblages could highlight the presence of different niches available for settlement of different taxa. Combined matrix analyses show that diatoms and macroinvertebrates co-occur, and their community assemblages are sometimes structured, while they appeared to be randomly assembled at other times. Whenever non-randomness of diatoms and macroinvertebrates co-occurrences was detected, it suggested aggregation. Moreover, the possible predatory relationship between different macroinvertebrates taxa should be investigated, as it could reveal important scenarios in the establishment of macroinvertebrate structured communities on plastic litter, including taxa that exploit different ecological niches. This could lead to an enrichment of the biological community within areas impacted by plastics.

Borrowing from the palaeolimnologists toolkit; the use of lake sediment cores in diagnosing the causes of freshwater species decline

Populations of freshwater species are experiencing dramatic declines globally. Tools that facilitate the diagnosis of decline and identify management solutions and/or restoration targets are thus vital. Typically approaches taken to diagnose decline are carried out over short timescales and rely upon identifying spatial associations between presence or abundance of declining species and variables hypothesised to be driving decline. The potential to contextualise observed declines on longer time scales, with a broader range of potential explanatory variables is frequently dismissed, because of a perceived lack of existing long-term data. In this study we explore the value of incorporating a longer-term perspective to decline diagnosis using the common scoter as a case study. The number of scoter breeding in Scotland has declined substantially since the 1970s. Hypotheses for decline include a reduction in macroinvertebrate food available for females and young at the breeding lakes. In this study we apply palaeolimnological techniques to generate standardised, long-term ecological data, enabling us to characterise recent changes at four common scoter breeding lakes. Our results demonstrate that the (macroinvertebrate) food resource of common scoter has, in fact, gradually increased in abundance at all four sites from ca. 1900, and that a further statistically significant increase in macroinvertebrate abundance occurred at ca. 1970. We draw on our palaeolimnological data, to explore alternative hypotheses for common scoter decline. Increases in overall abundance across multiple algal, macrophyte and macroinvertebrate taxa, combined with specific increases in nutrient tolerant taxa, and concurrent declines in nutrient sensitive taxa indicate that the lakes have experienced enrichment within their current oligotrophic state during the last 100 years, and that this trajectory has become more marked during the period of common scoter decline. There is no evidence of changes to habitat, turbidity or increased competition from fish. In the absence of within lake changes that could be detrimental to the benthic (and generalist) feeding common scoter, we conclude that factors outside of the lake, such as increased predation, associated with afforestation in the surrounding area, are the most plausible drivers of common scoter decline. Prioritisation/testing of management solutions that address these issues are indicated.

In situ effects of microplastics on the decomposition of aquatic macrophyte litter in eutrophic shallow lake sediments, China

The toxicity of microplastics (MPs) to aquatic organisms has been extensively studied recently. However, few studies have investigated the effects of MPs in sediments on aquatic ecosystem functioning. In the present study, we conducted an in situ experiment to explore the concentration-dependent effects (0.025%, 0.25%, 2.5%) and size-dependent effects (150–300 μm and 500–1000 μm) of polypropylene microplastics (PP MPs) on Vallisneria natans litter decomposition dynamics, in particular, the process associated with macroinvertebrates, microorganisms, as well as microalgae and/or cyanobacteria. The results showed that exposure to high concentrations and large sizes of PP MPs can accelerate leaf litter biomass loss and nutrition release. Moreover, microbial respiration, microalgal and/or cyanobacteria chlorophyll-a were also significantly affected by PP MPs. However, PP MPs have no effect on the abundance of associated macroinvertebrate during the experiment, despite the collection of five macroinvertebrate taxa from two functional feeding groups (i.e., collectors and scrapers). Therefore, our experiment demonstrated that PP MPs may enhance leaf litter decomposition through effected microbial metabolic activity, microalgal and/or cyanobacteria biomass in the sedimentary lake. Overall, our findings highlight that PP MPs have the potential to interfere with the basic ecological functions such as plant litter decomposition in aquatic environments.

Functional non‐equivalence in ecosystem engineers? Different freshwater mussels (Bivalvia: Unionidae) are associated with different macroinvertebrate communities in a subtropical lake

Abstract Freshwater mussels (Bivalvia: Unionidae) are often described as ecosystem engineers, with the capacity to alter abiotic habitats; this can facilitate certain macroinvertebrate taxa, increasing biodiversity and potentially altering community composition. Mussel species are often implicitly considered to be broad ecological equivalents, with similar impacts on abiotic environments and benthic communities. This assumption of redundancy is important in conservation approaches that aim to preserve ecosystem functioning, rather than species identity. We tested this assumption of equivalence in two species of subtropical freshwater mussels, Lamellidens marginalis and Parreysia caerulea, studying the associations between these mussel species and macroinvertebrate communities. We measured mussel density and abundance of macroinvertebrates, identified to family level, at 50 sites within Dhanmondi Lake, a heavily polluted sub‐tropical urban lake in Dhaka, Bangladesh. We investigated the associations of mussel density on different macroinvertebrate families, which we further classified into functional feeding groups (predators, scrapers, collectors and shredders). We found that densities of the two mussel species were negatively correlated in the 1–3‐m nearshore zone; average density of Lamellidens was 46.4 ± SE 3.6 individuals/0.25 m2, and average density of Parreysia was 6.4 ± SE 1.4 individuals/0.25 m2. In total, 2319 Lamellidens and 320 Parreysia specimens were recorded. Sites containing higher densities of Lamellidens had greater similarity in macroinvertebrate community composition, while there was no effect for Parreysia. Particular macroinvertebrate families and functional feeding groups were also associated with mussels; the majority of significant associations were with Lamellidens but not Parreysia. The clearest associations were with predators and scrapers, which increased in abundance with Lamellidens density. This provides support for a possible role for mussels in structuring freshwater invertebrate communities and emphasises the importance of species identity in these effects, with one possible keystone species (Lamellidens) largely accounting for mussel–invertebrate associations. While microhabitat variables (shading and sediment type) were poor predictors of abundance in any invertebrate taxa (including mussels), manipulative studies are needed to disentangle the direct effects of mussels from the role of overlapping habitat preference between mussels and other invertebrates. Our results highlight the importance of species identity in patterns of community composition, particularly for ecosystem engineer species. We also reinforce the need to test the assumption of ecological redundancy within communities.

Taxonomic and functional diversity of macroinvertebrates in sediment and macrophyte habitats: A case study, the Ibrahimia Canal, Nile River, Egypt

The taxonomic and functional diversities of macroinvertebrates are a critical indicator of ecosystem health. This study focuses on the taxonomic and functional diversities of the assemblage structure of macroinvertebrates in the Ibrahimia Canal, Egypt. They were compared across two different substrate habitats: sediment-associated and macrophytes-associated habitats. Significant variations in the taxonomic and biological trait community composition in the two substrate habitats were recorded, with high taxa abundance in sediment substrate and increased diversity in macrophyte substrate. In sediment substrates, burrow dweller and collector-filterer taxa were the main characteristics, while tube dweller and collector-gatherer were the main traits of macrophytes substrate. The taxonomic and functional indices tended to increase from sediment to macrophytes substrate; however, there was an increase in Rao’s quadratic entropy index (RaoQ) for sediment substrate habitat. Redundancy analyses explained the association between environmental factors and macroinvertebrate taxa and traits. Total suspended solids, dissolved oxygen, chemical demand oxygen, and phosphate were the key environmental drivers of the taxonomic and functional diversities of macroinvertebrates. Integration between the approaches to taxonomic and functional diversity is recommended to give insight into explaining and managing the freshwater ecosystem.

Organic matter sources and flows in tundra wetland food webs.

Arctic lowland tundra is often dominated by wetlands. As numbers and types of these wetlands change with climate warming, their invertebrate biomass and assemblages may also be affected. Increased influx of nutrients and dissolved organic matter (DOM) from thawing peat may alter the relative availability of organic matter (OM) sources, differentially affecting taxa with disparate dependence on those sources. In five shallow wetland types (<40 to 110 cm deep) and in littoral zones of deeper lakes (>150 cm), we used stable isotopes (δ13C, δ15N) to compare contributions of four OM sources (periphytic microalgae, cyanobacteria, macrophytes, peat) to the diets of nine macroinvertebrate taxa. Living macrophytes were not distinguishable isotopically from peat that likely contributed most DOM. Within invertebrate taxa, relative OM contributions were similar among all wetland types except deeper lakes. Physidae snails consumed substantial amounts of OM from cyanobacteria. However, for all other taxa examined, microalgae were the dominant or a major OM source (39-82%, mean 59%) in all wetland types except deeper lakes (20‒62%, mean 31%). Macrophytes and macrophyte-derived peat, likely consumed mostly indirectly as DOM-supported bacteria, ranged from 18‒61% (mean 41%) of ultimate OM sources in all wetland types except deeper lakes (38-80%, mean 69%). Invertebrate consumption of microalgal C may often have involved bacterial intermediates, or a mix of algae with bacteria consuming peat-derived OM. High production of periphyton with very low δ13C values were favored by continuous daylight illuminating shallow depths, high N and P levels, and high CO2 concentrations from bacterial respiration of peat-derived DOM. Although relative OM sources were similar across wetland types except deeper lakes, total invertebrate biomass was much higher in shallow wetlands with emergent vegetation. Impacts of warming on the availability of invertebrate prey to waterbirds will likely depend not on shifts in OM sources, but more on changes in overall number or area of shallow emergent wetlands.

Forage Fish Species Prefer Habitat within Designated Offshore Wind Energy Areas in the U.S. Northeast Shelf Ecosystem

AbstractAs the world develops sources of renewable energy, there is an intensifying interest in offshore wind energy production. The Northeast U.S. Continental Shelf (NES) ecosystem has favorable wind dynamics, with active development of wind energy. In this study, we present species distribution models that consider both occupancy and biomass responses for a broad spectrum of fish and macroinvertebrate taxa (n = 177). Building upon prior analyses, habitat was differentiated into overall and core habitats based on statistical distributions of habitat scores. Overall habitat was used to show each species' regional distribution based on fishery‐independent survey captures between 1976 and 2019, whereas core habitat represented where the focus of the species' abundance was located as a subset of overall habitat. Wind energy developments may modify the water column in ways that impact lower‐trophic‐level productivity; therefore, added attention was given to the response of forage species. Over 20% of species showed preferential use of putative and potential wind development areas, including a disproportionate number of forage taxa. Principal usage varied by season, with forage species like Atlantic Menhaden Brevoortia tyrannus and Atlantic Mackerel Scomber scombrus preferentially using the lease areas in spring and Round Herring Etrumeus teres and longfin inshore squid Doryteuthis pealeii using lease areas in autumn. For species with relatively low usage of the lease areas, there was a tendency for the usage related to overall habitat to be lower than usage for core habitat; in contrast, for species with high usage of the lease areas, that usage was higher for overall habitat than for core habitat. The area of habitat tended to have positive trends across species, with these positive trends being disproportionately higher among forage taxa. These results frame the importance of wind lease areas for species in the NES, particularly forage taxa that fulfill many important ecological functions.

Water source dynamics influence macroinvertebrate communities across groundwater-fed streams in a glacierized catchment

Groundwater contributions to streamflow significantly influence the structure and function of riverine ecosystems, particularly in glacierized catchments where there are marked differences in water sources and subsurface flow paths. Here, we investigated spatial and temporal variation in relationships between water sources, flow paths, physical and chemical processes, organic matter, microbial biofilms, and macroinvertebrates across groundwater-fed streams in the glacierized Toklat River catchment of Denali National Park, Alaska. Streams fed predominantly by seepage from the valley sides were perennial, whereas streams sustained by glacial meltwater seepage were ephemeral. Differences in environmental conditions between flow regimes appeared to influence spatial and temporal patterns of organic matter, linking to macroinvertebrate community dynamics. Macroinvertebrates in perennial streams were supported by fine particulate organic matter from subsurface flow paths during summer, transitioning to a combination of fine particulate matter and leaf litter in autumn. In comparison, macroinvertebrates inhabiting ephemeral streams, which only flowed during autumn, were supported by leaf litter. Some macroinvertebrate taxa were unaffected by turnover in organic matter, indicating potential plasticity in organic matter resource use. Findings highlight the importance of considering spatial and temporal variation in groundwater-fed streams, considering that projected hydrological changes under a changing climate may have significant implications for these systems.

Ecological characterisation of urban ponds in the Netherlands: a study based on data collected by volunteers

Blue space in the urban environment can positively contribute to public health and well-being. Many urban freshwater systems, however, are exposed to anthropogenic stressors, resulting in deteriorated water quality and biodiversity. Private garden ponds are essential elements of this blue space but little is known about their water quality since they are not monitored by water professionals. The Dutch citizen science initiative Waterdiertjes.nl focusses on biological water quality assessment using macroinvertebrates and launched a campaign to investigate garden ponds in 2021. The campaign yielded macroinvertebrate recordings in 60 garden ponds and limited additional information on dimensions, and presence of water vegetation and fish. Volunteers also investigated 92 public urban ponds in 2021. Combining both data allowed for evaluation of the similarity between both pond types. Analyses were also performed to discover the importance of pond dimensions and presence of aquatic vegetation or fish for the macroinvertebrate biodiversity and water quality. Multivariate analyses showed a considerable overlap in macroinvertebrate community composition between garden and public urban ponds. Results showed high variability in taxon richness, total macroinvertebrate density and water quality scores A significant, nonlinear relation was observed between pond depth and macroinvertebrate taxon richness with the highest richness at a depth of 0.5-1m. Submerged vegetation correlated significantly with taxon richness with little vegetation having the lowest richness. Presence of fish or floating vegetation was not significantly related to taxon richness, total density and water quality scores possibly due to unnatural conditions that underlie in garden ponds. Since water professionals and academic scientists do not monitor garden ponds, citizen science may provide valuable data on water quality and biodiversity in these waters. The present initiative showed that volunteers can successfully monitor understudied ecosystems and gather data on temporal and spatial scales complementary to professional data that lead to new (ecological) insights.

Forest buffer-strips mitigate the negative impact of oil palm plantations on stream communities

The global area cultivated with oil palm has doubled in the past two decades, causing deforestation, land-use change, freshwater pollution, and species loss in tropical ecosystems worldwide. Despite the palm-oil industry been linked to severe deterioration of freshwater ecosystems, most studies have focused on terrestrial environments, while freshwaters have been significantly less studied. We evaluated these impacts by contrasting freshwater macroinvertebrate communities and habitat conditions in 19 streams from primary forests (7), grazing lands (6), and oil palm plantations (6). In each stream, we measured environmental characteristics, e.g., habitat composition, canopy cover, substrate, water temperature, and water quality; and we identified and quantified the assemblage of macroinvertebrates. Streams in oil palm plantations lacking riparian forest strips showed warmer and more variable temperatures, higher turbidity, lower silica content, and poorer macroinvertebrate taxon richness than primary forests. Grazing lands showed higher conductivity and temperature, and lower dissolved oxygen and macroinvertebrate taxon richness than primary forests. In contrast, streams in oil palm plantations that conserved a riparian forest, showed a substrate composition, temperature, and canopy cover more similar to the ones in primary forests. These habitat improvements by riparian forests in the plantations increased macroinvertebrate taxon richness and maintained a community resembling more the one in primary forests. Therefore, the conversion of grazing lands (instead of primary forests) to oil palm plantations can increase freshwater taxon richness only if riparian native forests are safeguarded.

Species sensitivity and functional uniqueness determine the response of macroinvertebrate functional diversity to species loss in urban streams

Abstract Land‐use change, particularly urbanisation, has led to an unprecedented decline in species and functional diversity worldwide. However, the mechanism through which such species loss affects functional diversity remains unclear. Here, we aimed to elucidate this mechanism from the perspectives of the association between species sensitivity and functional uniqueness (i.e., their relative contribution to functional diversity) and their related functional traits. We collected stream macroinvertebrates and measured environmental and land‐use variables from 152 sites in the highly urbanised Qiantang River Basin in the Zhejiang Province of eastern China. Firstly, we evaluated the sensitivity to urbanisation and functional uniqueness of each macroinvertebrate taxon to identify their association patterns. Secondly, we examined the decline in functional diversity in response to taxon loss by comparing simulated ordered and random taxon loss scenarios. Finally, we identified sensitivity‐related traits (SRT) and functional uniqueness‐related traits (URT) using the Mann–Whitney U‐test to elucidate their role in shaping functional response patterns to taxon loss. Urbanisation showed a remarkable effect on the taxonomic and functional diversity of macroinvertebrates. Functional diversity declined nonlinearly with taxon loss, with the threshold response shifting to a rapid decline after 29.7%–60.0% taxa were lost. The sensitivities of ephemeropteran, plecopteran and trichopteran taxa (EPT) were negatively associated with their functional uniqueness, although this association was not detected when considering all macroinvertebrates. We identified 11 SRT and nine URT, but only one URT overlapped SRT. The association between species sensitivity and its functional uniqueness shapes functional decline patterns in response to taxon loss. Overlap patterns of SRT and URT offer novel insights into mechanisms underlying stress‐induced decline in functional diversity. The process of functional diversity decline in response to species loss caused by urbanisation also may be affected by species turnover or even compensated for by non‐native species in real world ecosystems. How functional diversity responds to species loss remains an open topic that needs to be cautiously addressed.

Hydromorphological discontinuities deeply modify the benthic multi-species assemblage diversity in a Mediterranean running river

The aim of the study was to investigate the modifications of the macroinvertebrate multi-species assemblage in relation to hydromorphological discontinues, since macroinvertebrates are traditionally exploited in water quality assessment activities. Three sampling sites characterized by different hydrological characteristics were selected in five stations along the River Aniene in Central Italy. We evaluated the macroinvertebrate structure, traits, biotic and diversity indices in relation to the erosive power. Among macroinvertebrate taxa, Elminthidae and Chironomidae families showed a particular occurrence pattern associated with the site at the base of vertical drop, characterized by the stronger hydrodynamic. However, the water quality status was high, not showing differences between the three sites. Our finding has a novelty value as similar studies on the investigation of the hydromorphological discontinuities on macroinvertebrate structure and ecological traits are very scarce in the literature.Graphical abstract

The ephemeral pans of Gras-Holpan: Mokala National Park, Northern Cape, South Africa

Ephemeral pans are transient natural habitats with harsh conditions found in semi-arid regions. These pans endure high evaporation rates, extreme temperatures and an overflow of water. Pans are characterised by dry land becoming submerged in water temporarily (flood-like) followed by a prolonged period absent of water (drought-like). Ephemeral pans are unique habitats that are essentially transient habitats from a freshwater system to increased salinity and eventually a dry landscape. Biodiversity associated with these pans must adapt to the transient environmental conditions. Unique adaptations of the biota for these habitats allow them to withstand extreme conditions. The objective of this study was to (1) identify changes in the water quality over time in the pans, to (2) identify succession of macro-invertebrates and (3) identify the water quality parameters of pans as drivers of macro-invertebrate assemblages. A total of five pans were measured in the Northern Cape province of South Africa located on the Savanna and Nama-Karoo biomes within a 4500 ha area. The measurements taken included water quality variables (pH, salinity, total dissolved solids [TDS]), taxon diversity and richness of macro-invertebrates and aquatic birdlife. Evaporation rate between the pans varied with time. There was a difference in the macro-invertebrate taxon richness between the pans. Macro-invertebrate taxon succession was observed over time and some macro-invertebrates showed confinement to pans of a particular biome. It was found that pH was significantly the most contributing factor to the taxon richness and diversity of the macro-invertebrates recorded, while the salinity and TDS increased with time as water evaporated.Conservation implications: The shrimps (fairy, clam and tadpole) were unique to the Nama-Karoo pans. It was found that pH (p 0.05) was the most contributing factor to the taxon richness and diversity of the macro-invertebrates recorded, and salinity and TDS increased with time as water evaporated.

Preliminary biological data of Sahel wetland ecosystems in Burkina Faso: Implications for ecological health assessment

Birds, amphibians, fish, and macroinvertebrates are useful indicators of ecological conditions and ensure considerable conservation value and tools for decision making in management of wetland ecosystems. However, the use of these organisms to monitor wetland ecosystems has rarely been explored in Western Africa. Whereas, we are currently facing to growing multiple anthropogenic pressures and climate warming that impact negatively our wetlands and the biodiversity. Notably, there is an urgent need of cost-effective tools for wetland ecosystems health assessment in Burkina Faso. In this study, we examined the taxonomic composition of birds, amphibians, fish, and macroinvertebrates and explored their potential use for monitoring wetland ecosystems. From our findings, measures of taxa composition and diversity respond to the gradients of anthropogenic alterations. Our results revealed that the highest diversity of fish and macroinvertebrates taxa was recorded in protected sites, whereas the lowest diversity was obtained in degraded sites. Additionally, the findings showed a strong and positive correlation between macroinvertebrates taxa and key water variables, whereas fish taxa were strongly correlated to xylal (deadwood) substrates. Most of bird’s species were recorded in tree-shrubs, and amphibians of protected wetlands were distinguished by identifying indicator taxa through indicator value index. African wetland ecosystems and biodiversity may be sustainably preserved through responsive monitoring programs of wetlands by limnologists.