Macroinvertebrate Diversity In Streams Research Articles

Patterns of diversity in stream macroinvertebrate communities in a low-gradient agricultural stream (Sydenham River, Ontario, Canada) were driven by surficial geology and catchment position

Abstract Freshwater biodiversity is increasingly at risk wherever land uses such as agriculture exert multiple stressors that degrade habitat quality. Although stream macroinvertebrates act as bioindicators for monitoring these impacts, their responses are context-specific: examining drivers of community composition is therefore important to understand the results of monitoring efforts. In a primarily agricultural landscape, 15 sites across the Sydenham River watershed, Ontario, Canada, were assessed for in-stream habitat quality and stream macroinvertebrate diversity. We predicted that community assemblage would be driven by differences in surficial geology across branch (east branch versus north branch) and catchment position (main stem versus tributary). We found that the main stem of the east branch was characterised by significantly higher proportions (P = 0.053) and abundance (P = 0.038) of Ephemeroptera–Plecoptera–Trichoptera (EPT) taxa than north branch sites were, and sites in the east and north branch tributaries were characterised by significantly lower Hilsenhoff Biotic Index (HBI) scores (P = 0.088). Redundancy analysis found that substrate size was the main driver of community composition, generating a model that described these patterns across branch and catchment position. Our findings suggest that EPT abundance and HBI scores were the variables that were most effective at revealing differences in stream communities due to agricultural impacts and that sediment size is an important driver of these patterns.

Long-term trends in stream benthic macroinvertebrate communities are driven by chemicals

BackgroundRecent studies indicate a partial recovery of European stream macroinvertebrate diversity. However, the key determinants shaping the overall community trends are only partly explored, owing to insufficient long-term environmental data collected in parallel with community responses. We investigate long-term trends in stream macroinvertebrate communities (i.e., taxonomic and trait composition and metrics), and explore their relationships to diverse environmental drivers (i.e., land-use, runoff, water temperature, and in-stream chemicals). We use macroinvertebrate data collected annually in spring and summer between 2007 and 2021 at four sampling sites within the Rhine-Main-Observatory Long-Term Ecological Research site. These sampling sites encompass a gradient from less-disturbed to disturbed conditions.ResultsOver time, shifts in taxonomic and trait composition and metrics indicated an improvement in environmental conditions. Long-term trends of biological trait metrics mirrored those for taxonomic metrics; for example, increases over time in taxonomic richness were paralleled by increases in functional richness and functional dispersion. Meanwhile, trends of ecological trait metrics were particularly driven by changes in environmental drivers. Land-use, water temperature, and runoff explained around 20% of the overall variance in long-term trends of macroinvertebrate communities. Water temperature and land-use played relatively equal roles in shaping taxonomic and trait composition and metric responses in spring, while water temperature emerged as the most influential driver in summer. However, when incorporating long-term chemical data as a more direct measurement of changes in land-use, the overall variance explained in macroinvertebrate community trends increased to c.a. 50% in both seasons.ConclusionsExamining more relevant driver variables beyond land-use and climate improves insights into why biodiversity exhibits long-term trends. We call for an increase in initiatives to link biodiversity monitoring with parallel sampling of relevant environmental drivers.

Characterizing the Chemical Profile of Biological Decline in Stormwater-Impacted Urban Watersheds.

Chemical contamination is an increasingly important conservation issue in urban runoff-impacted watersheds. Regulatory and restoration efforts typically evaluate limited conventional parameters and pollutants. However, complex urban chemical mixtures contain hundreds to thousands of organic contaminants that remain unidentified, unregulated, and poorly understood. This study aimed to develop broadly representative metrics of water quality impairment corresponding to previously documented biological degradation along gradients of human impacts. Stream samples (n = 65, baseflow/rainfall conditions, 2017-2018) were collected from 15 regional watersheds (Puget Sound, WA, USA) across an urbanization gradient defined by landscape characteristics. Surface water chemical composition characterized via non-targeted high-resolution mass spectrometry (7068 detections) was highly correlated with landscape-based urbanization gradient (p < 0.01) and season (p < 0.01). Landscape-scale changes in chemical composition closely aligned with two anchors of biological decline: coho salmon (Oncorhynchus kisutch) mortality risk (p < 0.001) and loss of stream macroinvertebrate diversity and abundance (p < 0.001). We isolated and identified 32 indicators for urban runoff impacts and corresponding receiving water ecological health, including well-known anthropogenic contaminants (e.g., caffeine, organophosphates, vehicle-derived chemicals), two related environmental transformation products, and a novel (methoxymethyl)melamine compound. Outcomes support data-directed selection of next-generation water quality indicators for prioritization and evaluation of watershed management efforts intended to protect aquatic ecosystems.

Temporal changes of biodiversity in urban running waters – Results of a twelve-year monitoring study

Freshwater biodiversity underlies severe threats, mainly suffering from habitat degradation by anthropogenic land use, in particular by urbanisation. However, recent long-term studies indicate recovery of stream macroinvertebrate diversity due to improved water quality at least in North America and Europe. We monitored macroinverbrates at 56 urban stream sites over a 12-year period (2009–2020) in Braunschweig, a German urban district. We utilised these data to investigate spatio-temporal changes in taxon richness and assemblage structure as well as factors potentially affecting the resulting patterns. Overall taxon richness was increasing over the study period, comprising both all taxa and taxa being indicators for healthy stream conditions. 53.6% of the sites had significant positive trends becoming most eminent since 2014, despite decelerating since 2018, the beginning of an extra-ordinary dry period. Only 10.7% of the study sites had negative trends. Assemblage structure was shaped by environmental factors like stream width and water quality. Over-average taxon richness including positive trends and higher numbers of indicator taxa of healthy stream conditions was found in streams with higher flow velocity, good saprobic conditions and more natural streambed structure. In contrast, low taxon richness and predominance of tolerant taxa were found in streams with more degraded conditions. Most of the environmental conditions having positive effects on taxon richness were improved by various programs set up by the environmental authorities. We therefore conclude, if urban stressors like organic pollution and structural degradation can be mitigated by revitalisation and water quality improvement, urban streams can have good potential for increasing biodiversity and improving ecological functioning.

The effects of road crossings on stream macro-invertebrate diversity

Although it is well known that the increasing size of the human population has a negative effect on freshwater biodiversity, the subject of whether or how the intersection of roads and streams (hereafter road crossings) influence the diversity of stream macro-invertebrates is under-researched. To fill this gap in our knowledge, we collected stream macro-invertebrates from road crossings (bridges and culverts) and compared their diversity with upstream and downstream sections. We found that road crossings had negative effects on the richness and abundance of native macro-invertebrates, as well as on the number of protected taxa. Our results showed also that alien individuals were more abundant at road crossings. These findings support the assumption that road crossings contribute to the spread of alien species. The assessment of environmental variables indicated that road crossings caused habitat modifications, and based on these it can be assumed that habitat modifications and associated phenomena (e.g. pollutants and storm events) were the major drivers of the observed patterns in biodiversity. Our results fill a knowledge gap and contribute to the deeper understanding of the effect of road crossings on freshwater biodiversity.

Stream Benthic Macroinvertebrate Assemblages Reveal the Importance of a Recently Established Freshwater Protected Area in a Tropical Watershed1

Unsustainable urbanization in the Indo-Pacific continues to threaten terrestrial and aquatic ecosystems due to habitat disturbances driven by human pressures. The Marikina Watershed, one of the most critical watersheds in the Philippines, has been exposed to economic and population growth resulting in landscape modification and water quality degradation. This led to establishment of the Upper Marikina River Basin Protected Landscape (UMRBPL) to rehabilitate the watershed ecosystem. To strengthen this conservation initiative, we aimed to assess whether the establishment of UMRBPL has been effective in conservation of benthic macroinvertebrate diversity in streams of the Marikina Watershed. Sixteen streams, eight from UMRBPL and eight from adjoining unprotected areas, were monitored for benthic macroinvertebrate assemblages and their habitat environments, such as pH, water temperature, dissolved oxygen, total dissolved solids, conductivity, salinity, and canopy openness. Principal component analysis and non-metric multidimensional scaling based on the environmental variables and biological metrics, respectively, revealed that habitat quality and benthic macroinvertebrate assemblages significantly differed between the protected and unprotected streams, with the former having better environment and higher biodiversity. More precisely, protected streams have significantly higher dissolved oxygen and lower canopy openness and material loadings as compared to unprotected streams. Consequently, taxon richness was four-fold higher in protected streams while stream quality indices based on abundance of key invertebrate groups (EPT and EPTC) were ten-fold higher in protected streams, as compared to unprotected streams. This study demonstrates that freshwater protected areas play crucial roles in the conservation of stream ecosystems and biodiversity under rapid urbanization in developing countries, like the Philippines.

Stream invertebrate diversity reduces with invasion of river banks by non‐native plants

Abstract Invasion of riparian zones by non‐native plants is a global issue and commonly perceived as a challenge for river and fishery managers, but the type and extent of ecological changes induced by such invasions remain poorly understood. Established effects on sediment delivery, allochthonous inputs, and channel shading could potentially alter aquatic macroinvertebrate assemblages, with implications for in‐stream ecological quality. We assessed responses in the diversity, quality, and heterogeneity of stream macroinvertebrate communities to riparian invasion by non‐native plants. Macroinvertebrates were collected from 24 sites on low order streams in central and southern Scotland during spring and autumn. The effect of invasive non‐native plants (INNP) on macroinvertebrates was assessed relative to that of local physical and chemical factors. Invasive non‐native plants cover was associated with stronger effects than other factors on local diversity of macroinvertebrates (33% reduction at the highest INNP cover) but also increased macroinvertebrate abundance across sites. Invaded sites were also associated with lower macroinvertebrate biomonitoring scores. Community composition differed between invaded and uninvaded sites in autumn, but not in spring. However, INNP influence on macroinvertebrate composition was generally secondary to that of physicochemical variables (e.g. channel shade, substrate diversity). We demonstrate that the influence of INNP extends beyond well‐known impacts on plant communities to reductions mainly in stream macroinvertebrate diversity. Combined with the negative impact on pollution‐sensitive macroinvertebrate taxa this raises concerns over the ecological health of streams with heavily invaded riparian zones. Our findings suggest that efforts to improve low order streams by actively managing severe riparian invasions are merited, but the size and uncertainty of the likely ecological gains must also be evaluated against the effort involved.

The added value of geodiversity indices in explaining variation of stream macroinvertebrate diversity

Geodiversity, i.e. the variety of the abiotic environment, is considered to be positively correlated to biodiversity. In streams, the importance of physical heterogeneity for biodiversity variation is well known, but the usefulness of explicitly measured geodiversity indices to account for biodiversity has not been tested. We developed a technique to measure in-stream geodiversity, based on different types of stream flow, geomorphological processes and landforms observed from photographs taken during the field work, and substrates based on traditional field observations. We further tested the utility of these geodiversity measures in explaining variation in the biodiversity of macroinvertebrates in near-pristine streams. Our specific objective was to examine the explanatory power of geodiversity compared to traditional environmental variables, such as water chemistry, depth and current velocity. While most biodiversity indices correlated more strongly with traditional environmental variables, the influence of geodiversity on biodiversity was also evident. Unique effect of flow richness on species richness and that of total geodiversity on functional richness were higher than those of the traditional environmental variables. Our findings suggested that in-stream geodiversity offers a valuable concept for characterizing stream habitats. If further developed and tested, in-stream geodiversity can be used as a cost-efficient proxy to explain variation in biodiversity in stream environments.

Do productivity and disturbance interact to modulate macroinvertebrate diversity in streams?

Although disturbance and productivity are clearly strong influences on lotic diversity, rarely have their interactive effects been studied in running water systems. We hypothesised that the presence or absence of canopy cover in streams would alter productivity- disturbance-diversity relationships due to differential effects on the food base, and tested this hypothesis in 47 mountain streams in the central North Island of New Zealand. Canopy cover had no influence on algal biomass in these streams, but a link between distur- bance and productivity was found in open canopy streams where taxonomic richness of invertebrates increased log-linearly with increasing algal biomass and peaked at intermediate levels of disturbance. Community evenness declined with disturbance, but only at closed canopy sites where both invertebrate taxonomic richness and Simpson's diversity index were higher. Although there was a peak in richness at intermediate rates of disturbance, our results do not directly match predictions of the dynamic equilibrium model which predicts that the level of disturbance maximising diversity interacts with habitat productiv- ity. Rather, we suggest the combined effects of productivity and disturbance are additive rather than multiplicative such that productivity simply sets the upper limit to richness in streams.

Rapid assessment of headwater stream macroinvertebrate diversity: an evaluation of surrogates across a land-use gradient

Implementation of policies about the conservation and restoration of aquatic ecosystems' biodiversity and ecological integrity requires rapid assessment methods. The landscapes of the Carpathian Mountains, spanning an unusually steep gradient of land-use intensity from a European perspective, offer great opportunities for evaluating such methods. Focusing on the orders Ephemeroptera, Plecoptera and Trichoptera (EPT), we evaluated three approaches for assessing macroinvertebrate species richness in second and third order streams: (1) the use of data at higher taxonomic levels, (2) the use of species-level data, and (3) the use of abundance data. The number of families was a reliable indicator of species richness within EPT. Species richness of Trichoptera was strongly correlated to species richness in Ephemeroptera and Plecoptera, and thus in the EPT group as a whole, whereas species richness in Ephemeroptera and Plecoptera did not perform as well. We found little evidence for the usefulness of abundance data as a surrogate for species richness within orders, except in Plecoptera. Taxa richness in EPT was generally positively related to forest cover in the catchments and negatively related to the proportion of agricultural land. EPT taxa richness could be used to distinguish between High/Good quality classes and those of lower ecological quality according to the EU Water Framework Directive. Our results suggest that assessments focusing on the family level provide a cost-efficient alternative to species-level assessments in second and third order streams, and point at Trichoptera as a potential indicator group.

Spatial patterns of macroinvertebrate diversity in New Zealand springbrooks and rhithral streams

Spatial patterns in macroinvertebrate communities were examined in 4 to 5 rheocrene springbrooks and 4 to 5 nearby rhithral streams in 4 different regions of New Zealand. Physicochemical attributes of springbrooks and rhithral streams were similar, but springbrooks were more stable. Standing crops of periphyton biomass, epilithic C, and organic matter were greater and more variable in springbrooks than in rhithral streams. The number of macroinvertebrate taxa and the total number of individuals were greater at more stable sites. Altitude, habitat stability, and food resource levels were the best predictors of the number of macroinvertebrate taxa, whereas pH, PO4 concentration, habitat stability, and food resource levels were the best predictors of the total number of individuals at a site. Differences in the number of macroinvertebrate taxa between Northern Hemisphere and New Zealand springbrooks may be related to the larger diversity of macroinvertebrate predators in New Zealand springbrooks and to the fact that many New Zealand invertebrates do not use temperature-mediated life-history cues. Altitude, which limits invertebrate dispersal, also may play an important role in determining the maximum number of macroinvertebrate taxa in a given stream. A dispersal–stability framework is proposed to explain the observed patterns of macroinvertebrate diversity in these streams. The general pattern of noninsect dominance in lowland springs may be the result of the interaction between dispersal ability and the effects of the last glaciation.

Unifying the relationships of species richness to productivity and disturbance.

Although species richness has been hypothesized to be highest at 'intermediate' levels of disturbance, empirical studies have demonstrated that the disturbance-diversity relationship can be either negative or positive depending on productivity On the other hand, hypothesized productivity diversity relationships can be positive, negative or unimodal, as confirmed by empirical studies. However, it has remained unclear under what conditions each pattern is realized, and there is little agreement about the mechanisms that generate these diverse patterns. In this study, I present a model that synthesizes these separately developed hypotheses and shows that the interactive effects of disturbance and productivity on the competitive outcome of multispecies dynamics can result in these diverse relationships of species richness to disturbance and productivity The predicted productivity diversity relationship is unimodal but the productivity level that maximizes species richness increases with increasing disturbance. Similarly, the predicted disturbance diversity relationship is unimodal but the peak moves to higher disturbance levels with increasing productivity Further, these patterns are well explained by the opposite effects of productivity and disturbance on competitive outcome that are suggested by the change in community composition along these two environmental gradients: higher productivity favours superior competitors while higher disturbance levels favour inferior competitors.