Macroinvertebrate Benthos Research Articles

Advances in selection mechanism of aquatic insects on water flow velocity and substrate in small mountain rivers

As a major group of macroinvertebrate benthos, aquatic insects can reflect the status of river ecosystem to a great extent, and are one of the important biological monitoring indicators. Sediment and flow velocity are very important environmental factors which can affect community structure and biological characteristics of aquatic insects in rivers. However, there were few studies on the relationship between benthos and the two factors at home and abroad. In future, it is suggested to use physical model to simulate and construct the coupling relationship between diversity index of aquatic insects, flow velocity and sediment, and can reveal the selection mechanism of aquatic insects on velocity and sediment, so as to provide scientific basis for the protection and restoration of aquatic habitat of small rivers in mountainous areas.

An Irrigation Canal as a Lotic Mesocosm: Examining the Relationship between Macroinvertebrate Benthos and Drift

Abstract. We explored the notion that small canals could be good experimental proxies of streams by documenting physiochemical parameters and macroinvertebrate community development in an aridland irrigation canal. Further, we tested the production-compensation hypothesis between benthic invertebrates and invertebrates in the water column (drift). If the hypothesis held, invertebrates in the drift would be low until the benthic carrying capacity was reached; then organisms in the drift would increase as individuals avoided overcrowded conditions in the substrate. In a small, naturalized freshwater canal, we sampled macroinvertebrates in the substrate and those in the drift once every 2 weeks over 170 days (May–October). We placed macroinvertebrates into functional feeding groups (FFG) and examined these groups along with total density and taxa richness. We found no density-dependent relationship either in FFG or total density between the benthos and invertebrates in the drift. Our negative results might i...

Response of benthic macroinvertebrates to gradients in hydrological connectivity: a comparison of temperate, subtropical, Mediterranean and semiarid river floodplains

Summary Despite a general recognition that benthic macroinvertebrates respond to changes in hydrological connectivity within floodplain ecosystems, no consensus about patterns in community structure and ecosystem processes across large scales and different climates has yet been established. Such knowledge is necessary since anthropogenic activities continue to alter the natural hydrogeomorphology of large floodplains, with most consequences for aquatic communities remaining unknown. Using information from six large rivers located in four different climate regions (humid subtropical, maritime temperate, Mediterranean and dry semi‐arid), we compared benthic macroinvertebrate responses along lateral gradients of hydrological connectivity. We tested hypotheses related to differences among climate regions and to similar hydrological constraints within any one climate. The large geographical scale covered by this study provides the first comprehensive comparison of aquatic community patterns across hydrological gradients under different climatic settings. Multivariate ordinations demonstrated a higher overlap of trait community composition (50% variance explained by the first two axes) than taxonomic composition (15%) among floodplains, displaying high interclimate trait stability. The taxonomy‐based ordination separated the subtropical floodplain, with an average 86% of non‐insect taxa, from the insect‐dominated temperate, Mediterranean and semi‐arid floodplains (with >50% insect abundance). In the trait‐based ordination, large body size (60% of organisms >4 cm) and long lifespan duration (80% of organisms) discriminated the subtropical from the other five studied floodplains. Across a gradient of lateral connectivity, linear mixed effect (LME) models supported seven of 15 hypotheses, which suggests remarkably consistent macroinvertebrate patterns in floodplains regardless of the climate regime. Taxon and trait richness were positively related and peaked at sites of intermediate hydrological connectivity. Our predictions about the feeding guilds of macroinvertebrates (e.g. that shredders and scrapers would be more abundant in connected channels, and predators and deposit feeders at isolated sites) were more strongly supported by the data than those about life history (e.g. plurivoltinism and short lifespan would be better represented in connected channels). This difference was related to the influence of extended periods of hydrological disconnection as disturbance in addition to flooding. Trait stability across hydrological connectivity provides a meaningful ecological context for the comparison of the macroinvertebrate benthos among climatic zones, where taxonomic composition differs strongly. In addition, trait similarities and dissimilarities found in this study suggest that large‐scale biogeographical filters do operate on communities, resulting in different trait combinations in temperate and Mediterranean floodplains when compared to semi‐arid and subtropical environments. The extent to which global macroecological factors (i.e. climate, dispersal history) and local biotic and abiotic factors (i.e. drought frequency, habitat structure, water chemistry) contribute to this difference requires further investigation.

Stream inflow and predation risk affect littoral habitat selection by benthic fish

Summary1. We examined small, fishless headwater streams to determine whether transport of macroinvertebrates into the littoral zone of an oligotrophic lake augmented food availability for Cottus asper, an abundant predatory fish in our study system. We sampled fish and macroinvertebrates during the recruitment and growth season of 2 years, either monthly (2004) or bi‐monthly (2005), to observe whether stream inputs increased prey availability and whether variation in total macroinvertebrate biomass was tracked by fish.2. Observations from eight headwater streams indicated that streams did not increase the total macroinvertebrate biomass in the shallow littoral zone at stream inflows, relative to adjacent plots without stream inputs (controls). The taxonomic composition of stream macroinvertebrates drifting toward the lake differed from that in the littoral lake benthos itself, although there was no evidence of any species change in the composition of the littoral benthos brought about by stream inputs.3. Although streams made no measurable contribution to the biomass or taxonomic composition of the littoral macroinvertebrate benthos, there was substantial temporal variation in biomass among the eight sites for each of the (n = 7) sample periods during which observations were made. Variation in total biomass was primarily a function of bottom slope and benthic substrata in the lake habitats. Dominant taxonomic groups were Baetidae, Ephemerellidae (two genera), Leptophlebiidae, Chironomidae (three subfamilies) and Perlodidae, although we did not determine the specific substratum affinities of each taxon.4. Mixed effects linear models identified a significant interaction between macroinvertebrate biomass and plot type (stream inflow vs. control) associated with fish abundance. Across the observed range of macroinvertebrate biomass, fish showed a significant preference for stream inflows, but more closely tracked food availability in the controls. For young‐of‐the‐year (YOY), a negative effect of temperature was also included in the model, and we observed lower temperatures at stream inflows. However, abundance of predatory adults affected habitat selection for YOY. Lake‐bottom slope also accounted for variation in abundance in both fish models.5. Our results suggest that the effect of fishless headwater streams on downstream fish may not always be through direct delivery of food. In this study system, fish preferred stream inflow plots, but this preference interacted with macroinvertebrate biomass in a manner that was difficult to explain. For YOY, predation risk was related to the preference for stream inflows, although the specific factor that mitigates predation risk remains poorly understood.

Long-term trends in Loch Leven invertebrate communities

Detailed studies of the macroinvertebrate benthos and zooplankton communities in Loch Leven, the largest shallow lowland lake in Scotland, UK, were carried out from 1966 to 1973 as part of the International Biological Programme (IBP). The results revealed a reduction in species diversity that was attributed to increasing eutrophication. This work provides a baseline against which the response of the invertebrate communities to subsequent changes in management can be assessed. This article compares macroinvertebrate benthos and zooplankton data from the IBP study with the post-IBP era during which changes at Loch Leven included a 60% reduction in the phosphorus input from external sources and variations in fish stocking rates. Only in recent years has there been evidence of ecological recovery by the invertebrate communities: the number of macroinvertebrate and zooplankton taxa has increased (including taxa considered to be sensitive to nutrient enrichment) and invertebrate abundances have declined. These changes appear to reflect the improvements in water quality and habitat conditions at Loch Leven that have occurred as a result of the recent reduction in nutrient loads, albeit with a substantial delay before any ecological response could be detected. This time lag in recovery has important implications for assessing improvements in the ecological status of other lake systems, as is required by the EU Water Framework Directive.

Long-term changes in the littoral benthos of a Norwegian subalpine lake following the introduction of the European minnow (Phoxinus phoxinus)

The littoral benthos of the subalpine lake, Øvre Heimdalsvatn, has been documented in a series of investigations carried out in 1972, 1976, 1985 and 2000. During this 28-year period there have been major changes in the benthos of the lake following the introduction of European minnow (Phoxinus phoxinus) into the lake where brown trout (Salmo trutta) was formerly the sole species. In 1972 Ephemeroptera, Trichoptera, Plecoptera and Gammarus lacustris dominated the macrobenthos, constituting 85% of faunal numbers, while Chironomidae and Oligochaeta made up only c. 6%. However, by 1976, chironomids and oligochaetes had increased in relative abundance, while G. lacustris declined. This trend towards a dominance of chironomids and oligochaetes was confirmed in 1985 and 2000, although absolute numbers of Ephemeroptera, Plecoptera and Trichoptera increased in 2000 relative to 1972 values. Gammarus lacustris had a 2-year life cycle in Øvre Heimdalsvatn. In 1972 there were significantly more females than males, but by 1976 and through to 2000 there were greater numbers of males. Despite this reduction in females, numbers of juveniles increased, although mortality, probably due to increased predation from minnows, was higher than earlier. The introduction of the alien species, the European minnow, into Øvre Heimdalsvatn has clearly changed the composition and structure of the littoral macroinvertebrate benthos.

Some observations on Macro-invertebrate benthos of Lake Volta at Yeji Area(Stratum VII) thirty years after impoundment

Some observations on Macro-invertebrate benthos of Lake Volta at Yeji Area(Stratum VII) thirty years after impoundment

Spatial scale and ecological relationships between the macroinvertebrate communities of stony habitats of streams and lakes

Summary1. Comparative studies of distinct, but not ecologically isolated, systems such as lakes and streams may improve our understanding of the importance of ecological linkages in aquatic ecosystems.2. In this study we compared the macroinvertebrate benthos of stony habitats in Swedish lakes and streams. Community composition was used to evaluate zoogeographic patterns and functional feeding guilds were used to identify mechanisms potentially affecting such patterns.3. Stream communities were generally more diverse and species‐rich and had a higher proportion of grazers, shredders and passive‐filter feeders than lakes. Lake communities had a higher proportion of predators and collector‐gatherers. Of the 10 most common taxa, only Leptophlebia mayflies, clams (Sphaeriidae) and the isopod Asellus aquaticus were recorded in both lakes and streams.4. Among‐site variance in macroinvertebrate communities accounted for by regional‐scale variables was low (6.4% for lakes and 10.1% for streams), compared with that by local‐scale variables (21% for lakes and 37.6% for streams). For lakes, the among‐site variance in macroinvertebrate communities was best explained by habitat‐scale characteristics followed by ecosystem, riparian, catchment, geographic position and ecoregion. For streams, the variance in macroinvertebrate communities was best explained by ecosystem characteristics followed by habitat, catchment, riparian, ecoregion and geographic position.5. Conspicuous differences in spatial pattern were revealed between lakes and streams. For lakes, the most unequivocal differences in community composition and function occurred at the transition zone between the mixed forests in the south and the boreal coniferous forests in the north. Surprisingly, streams did not respond as strongly to profound landscape‐level differences in climate and vegetation cover.6. The spatial differences noted between macroinvertebrate communities of lakes and streams may be because of differences in retention of detrital matter. Our findings imply that detrital inputs are qualitatively similar, but that the retention and processing of coarse particulate organic matter was presumably higher in lake littoral regions than in stream riffle habitats.7. Although our findings support the conjecture that species distribution is determined fundamentally by conditions prevailing at the local‐scale, regional factors such as land use/type and the role of history were important and seemingly act as strong determinants of large‐scale patterns in biodiversity.

Are macroinvertebrates in high altitude streams affected by oxygen deficiency?

Summary1. The solubility of oxygen in water increases with decreasing temperature. This has led to a general perception of cold, high mountain streams as more oxygen rich than warmer lowland streams, and that macroinvertebrates inhabiting high altitude streams have had no need to adapt to critical oxygen conditions. However, this fails to take into account that oxygen solubility declines with decreasing atmospheric pressure, which may be of importance at high altitudes.2. Based on samples of macroinvertebrate benthos and in situ measurements of respiratory oxygen demand of macroinvertebrates in small streams from sea level to 4000 m a.s.l. in Ecuador, we determined predicted oxygen availability, oxygen demand and macroinvertebrate assemblage structure along this wide altitudinal gradient.3. We show that the predicted oxygen availability at 4000 m a.s.l. is only one fifth of that at sea level, whereas the mean weight‐specific respiratory rate of macroinvertebrates declined by only 50%, from 400 to 3800 m. We suggest that this disproportionately large gap between availability and demand of oxygen at high altitudes may imply a potential oxygen deficiency for the fauna, and we discuss how oxygen deficiency can be expected to affect macroinvertebrates in high altitude streams.4. Finally, we present preliminary data on the predicted response to oxygen deficiency of macroinvertebrate assemblages in high altitude streams. Compared with lowland streams, assemblages in natural high altitude streams include relatively few groups normally regarded as oxygen‐sensitive. Nevertheless, high altitude assemblages react more strongly to lowering of oxygen saturation, and are thus more sensitive to organic pollution.5. Oxygen deficiency has been overlooked completely in studies of the altitudinal distribution of species and aquatic communities. We argue that oxygen deficiency may be a potentially important factor, and that more focus on this topic is likely to produce significant new insights in aquatic community ecology.

Benthos and macroinvertebrate drift in six streams differing in alkalinity

The productive capacity of aquatic systems often is equated with the ‘chemical richness’ of the water. A primary objective of the present study was to relate macroinvertebrate benthos and drift to a streams' productive capacity as indicated by absolute levels of alkalinity. We tested this relationship in six 2nd–3rd order tributaries of the Salmon River, Idaho that ranged in alkalinity from 50 to 360 mg 1−1. Benthic density and biomass, drift biomass, and benthic organic matter increased with increasing levels of alkalinity, although not all relationships were significant. The proportion of drift biomass to benthic biomass was similar among study streams suggesting that drift was primarily passive during the study period. The data suggest that spatial variations in landscape-scale geology may indirectly affect spatial patterns of macroinvertebrate benthic and drift standing crops among streams within a single river basin by mediating lotic chemical richness as found among tributaries of the Salmon River basin.

Prey availability and diet of juvenile brown trout (Salmo trutta) in relation to riparian willows (Salix‐spp.) in three New Zealand streams

Abstract Macroinvertebrate benthos and drift and the diet of juvenile brown trout (Salmo trutta) were investigated in willowed and non‐willowed sections of three New Zealand streams during summer. The abundance and biomass of the principal macroinvertebrate taxa in the benthos and daytime drift differed in relation to riparian willow (Salix spp.) density, but the trends were not consistent across all three streams. Crustacea, Ephemeroptera, Trichoptera, and Diptera comprised a major proportion of the diet of juvenile trout. Diets of trout from non‐willowed and willowed sections were dissimilar in three of five pair‐wise comparisons. In all three streams, juvenile trout fed selectively, with the amphipod Paracalliope fluviatilis, ephemeropteran Deleatidium, and trichopterans Aoteapsyche and Hydrobiosidae being the preferred prey. Their avoidance of the gastropod Potamopyrgus antipodarum, trichopteran Oxye‐thira albiceps, coleopteran Hydora, and drift of terrestrial origin appeared to occur in all streams. ...

Impact of an Acid Spill on the Resident Fauna of the York River and its Recovery

Abstract As a result of a sulphuric acid spill in June 1982 at the Mines Gaspé operation in Murdochville, Québec, water quality of effluents being discharged into the headwaters of the York River was temporarily impaired. It rapidly became apparent that the aquatic fauna of this important Atlantic salmon river had been affected in some areas. This paper provides an overview of the results obtained in biological studies (Atlantic salmon population and benthic communities) carried out by Beak Consultants Ltd. and Noranda Technology Centre, annually, from 1982 to 1985. The biological and water chemistry surveys carried out during this four-year period indicated a short duration event of high dissolved metal levels, primarily copper, shortly after the spill, followed by a rapid improvement in water quality. Both the aquatic macroinvertebrate benthos and fish life in the river were negatively impacted. The nature and degree of this impact as well as the subsequent recolonization of aquatic habitats by both groups were observed and documented. The most affected aquatic groups in 1982 were the youngest salmon age classes (0+ and 1+) along with the intermediate and sensitive benthic communities. This impact was mainly observed in the upper and middle river section. Maintenance of suitable water quality during the following years has permitted excellent survival rates for juvenile salmon and recolonization of benthic habitats by sensitive species. This has contributed to the gradual re-establishment of a natural aquatic fauna in the York River. More recent surveys carried out since 1985 confirm that the quality of the York River ecosystem has been maintained and suggest that the survival rates observed for juvenile salmon are higher than the theoretical values usually used in salmon production models.

An assessment of short-term depletion of stream macroinvertebrate benthos by drift

A study was conducted to determine if emigration of drifting macroinvertebrates from a stream riffle which was blocked for one week from immigration by upstream colonists significantly reduced the abundance of drift collected from the tail of the riffle. The head of a 9 m long riffle of a 2nd order stream in Maryland (USA) was blocked from incoming drift by a 250 μm mesh weir. Upstream immigration of invertebrates into the riffle was largely prevented by a partition placed at the tail of the riffle which held the drift nets. Benthos and drift samples were collected from the riffle prior to weir placement and following its removal, and drift was collected at dusk on each day. No difference in drift or in benthic abundance between the beginning and end of the study was observed. This is largely attributed to recruitment of immature insects (primarily hatching of eggs present at the outset), particularly of Dolophilodes distinctus and species of Tanytarsini, from within the riffle. Results suggest that recruitment of riffle species is of sufficient magnitude to more than compensate for short-term riffle depletion due to drift. Samples of drifting and non-drifting (benthic) animals were held without food for 12 h after collection and mortality within each group was determined. The mortality of drifting animals was three-fold that of benthic animals.

The use of indicator organisms to assess aquatic pollution following a motorway insecticide spill

In April 1985, a transporter carrying the insecticide “Dursban” was involved in an accident near the M11/M25 interchange at Theydon Garnon, Essex. The resultant spill allowed a substantial amount of insecticide to enter “Brook House” Brook; a tributary of the River Roding. The macro-invertebrate benthos of the River Roding and two of its tributaries was sampled six months after the spill, at sites affected and unaffected by insecticide. Three distinct distribution responses by the fauna are identified and used to assess the environmental impact of the pollution. There was a sharp decrease in the type and number of organisms surviving in the affected parts of the river compared with unaffected regions. Re-population by some insecticide sensitive species was also observed. The effects of the spill are further investigated using hydrobiological indices.

Ecology of the Suldalslågen river in western Norway before its regulation

The River Suldalslågen, 22 km in length, situated in Rogaland province in western Norway, has been studied over a period of four years. The macro-invertebrate benthos was low in abundance especially in August and September. The main biomass was contributed by large case-bearing caddis-fly larvae, such as Potamophylax latipenis, which are shredders. The fauna composition of the upper and lower reaches of the river differed widely. Filter feeders, such as the caddis fly Polycentropus flavomaculatus, occurred in large numbers below the lake outlet, while shredders were predominant in the lower reaches. Large quantities of planktonic Crustacea, washed out ot the Suldalsvatn lake, were present in the river during the summer months. The Suldalslågen river is primarily a recruitment area for salmon and sea trout. Interestingly, the diet of the young salmonids did not show a close relationship to the available invertebrate biomass. For example, young salmon almost completely neglected the large caddis-fly larvae, while planktonic Crustacea washed out from Suldalsvatn and adult insects were taken in large numbers. A large proportion of the food supplies of both the salmon fry and parr were thus produced outside the river system. In 1962, for example, 34% of the food of the parr and 43% of that of the fry was produced in other, ecosystems than the river one.

The influence of surface runoff on the macro-invertebrate fauna of an urban stream

Hydrobiological indices were applied to samples of the macro-invertebrate benthos from an urban stream. A range of physico-chemical parameters from water samples were also determined. There was a significant deterioration in water quality along the stream from its comparatively rural source to its urbanised section. A model, derived by multivariate analysis, to predict the community diversity index of the stream biota from observed physico-chemical parameters was satisfactory for fairly clean water and for moderate levels of pollution, but not for severe levels of pollution.

Heavy metal pollution of the river Irwell (Lancashire, UK) demonstrated by analysis of substrate materials and macroinvertebrate tissue

The macroinvertebrate benthos of the River Irwell is impoverished to an extent that cannot be explained solely in terms of organic pollution. Relatively high dissolved oxygen levels are maintained as a result of turbulence. Atomic absorption spectrophotometry reveals substrate-bound levels of lead, copper and zinc higher than those recorded for an unpolluted river over almost the entire length of the Irwell, and at some sites the contamination is particularly severe. Concentrations in water are very low and it appears that high pH (about 7) leads to rapid precipitation of the discharged metals to substrate materials. The relationships between levels of the metals in substrate materials and in the tissues of Asellus aquaticus L. and Erpobdella octoculata (L.) have been investigated.

Comparison of Stomach Contents and Condition of Two Catfish Species Living at Ambient Temperatures and in a Heated Discharge

The lower condition factors for two catfish species in water heated by effluents from APCo's Glen Lyn, Virginia plant as compared to control areas probably is not due to lack of food as evidenced by macroinvertebrate sampling and the fact that only 4.3 percent of the catfish stomachs were empty. Results suggested that young-of-the-year channel catfish were nonselectively eating food organisms present at both control and heated stations. The difference between stomach contents of flatheat catfish from the heated site and fauna available at that site indicated that fish were either moving out of the heated area to feed or were selectively feeding on organisms (particularly mayflies) which were in the substrate or drifted into the heated area. Stomach contents of the two species and distribution and abundance of the macroinvertebrate benthos community are detailed. (RFC)