Indicators Of Biological Integrity Research Articles

Urban rain-fed lakes: macro-invertebrate assemblages associated with Egeria najas as indicators of biological integrity in wetlands of Corrientes Province (Argentina)

In northeast Corrientes Province, there are more than 50,000 semi-rounded shallow rain-fed lakes. Several lakes have been disturbed mainly because urbanization causes eutrophication due to the illegal discharge of wastewater. We compared 22 metrics based on the structural attributes of macro-invertebrates associated with Egeria najas across seasons between five lakes with different human disturbance levels. Sixty-six samples of E. najas and associated invertebrates were collected seasonally using a net with an area of 962 cm2. A total of 17,737 macro-invertebrates of eight major groups, 35 families and 30 genera were recorded. The total macro-invertebrate abundance (number of individuals per plant dry weigh) and the family richness were significantly higher in less disturbed lakes than those under human disturbance, but the differences between seasons were not significant. Non-metric multidimensional scaling analysis differentiated the macro-invertebrate abundances between the more and less disturbed lakes; instead, the diversity indices were not useful for measuring the changes in the studied lakes. Besides, total number of taxa, number of EOT (Ephemeroptera, Odonata, Trichoptera) taxa, abundance and proportion of Trichoptera and abundance of Chironomidae reflected significant differences between the more and less disturbed lakes. Our results suggest that seven invertebrate metrics respond to urbanization, and they could be used to assess biological integrity of the studied lakes in complement of chemical monitoring of water quality. Management efforts should focus on the maintenance of macrophyte stands that provide high invertebrate diversity, which serve as food for a wide variety of fish.

Understanding the impacts of agriculture on Andean stream ecosystems of Colombia: a causal analysis using aquatic macroinvertebrates as indicators of biological integrity

The pressures of a growing population and a fluctuating economy have caused extensive landuse transformations in the Colombian Andes, and >63% of the natural land cover has been replaced by cattle and crop fields. Despite the obvious importance of agriculture as a driver of stream degradation, the specific effects of agriculture on low-order streams of the Andean region are poorly understood. We used aquatic macroinvertebrates as indicators of biological integrity and applied structural equation modeling (SEM) to explore mechanisms through which local agricultural practices degrade headwater streams of the Colombian coffee-growing region. Our results suggest that agriculture affects the aquatic macroinvertebrate community indirectly by increasing the concentration of NH3-N in the water and reducing the width of the riparian forest. Moreover, through the reduction of riparian forest width, agriculture increased % slow-flowing habitats and decreased the availability of coarse substrates in the reach, which also had important effects on the benthic community. These results indicate that local farming practices, such as the elimination of the riparian forest and the use of riparian zones for crops and cattle grazing, are responsible for most of the effects of agriculture on streams in this region. Our results also highlight the importance of further research to formulate management alternatives relevant to the local context.

Larval fish assemblage recovery: a reflection of environmental change in a large degraded river

AbstractEstuaries are globally important to fisheries but face many anthropogenic stressors that reduce water quality and degrade benthic habitat. The Maumee River estuary has been degraded by industrial contaminants, high sediment and nutrient loads, channelization and elimination of surrounding wetlands, lessening its value as spawning habitat for fishes of Lake Erie. Regulation and better management practices (BMPs) in the watershed have improved the water quality in this estuary, which should result in a response of the biotic community. We compared recent (2010/2011) larval fish assemblage data to similar data from the 1970s (1976/1977) in order to identify changes due to improved water and habitat quality. Family‐level diversity was greater in recent study years compared to the 1970s and family richness increased from 6 to 10. In addition, the abundance of lithophilic spawning fishes was significantly greater in the recent study years. Increased diversity and family richness were consistent with increased water quality in the Maumee River whereas the observed increase in abundance of lithophilic spawners was consistent with an increase in the amount or quality of benthic habitat used by species in these families for spawning. Better wastewater management and agricultural practices in coastal watersheds can benefit the early life stages of fishes, thus benefitting coastal fisheries. Furthermore, larval fish assemblages may be useful indicators of biological integrity because of their sensitivities to environmental change. Routine sampling of estuarine larval fish assemblages could provide practitioners with insight into ecosystem changes and measure the response of the biotic community to restoration.

Use of single versus multiple biotic communities as indicators of biological integrity in northern prairie wetlands

As much as 70% of prairie wetlands in Canada have been lost. Although further degradation of natural wetlands is considered to be somewhat offset by wetland construction and restoration, Canada lacks bioassessment tools that can track ecosystem health in prairie wetlands. Indices of biological integrity (IBIs) use one or more biotic communities to compare the biological condition of a particular site to conditions found in least-impacted reference sites. Using the IBI approach, we evaluated the potential of 5 biotic communities to assess wetland health in northern prairie wetlands in Canada. Vegetation in the wet meadow, emergent and open-water zones as well as wetland-dependent songbirds and waterbirds were sampled at 81 semi-permanent/permanent natural and compensation wetlands spanning an environmental stress gradient. Metrics with strong linear relationships to the stress gradient (R2>0.2) were combined into an IBI for each biotic community and were subsequently validated at a suite of test sites. After validation, the entire data set was combined and each IBI was evaluated based on its linear relationship to environmental stress. Wet meadow zone vegetation was a strong indicator of environmental stress (R2=0.68, p<0.001), as was the wetland-dependent songbird community (R2=0.59, p<0.001). The emergent zone vegetation community was a relatively weak and inconsistent indicator of environmental stress, while the open-water zone vegetation and waterbird communities were poor indicators. To evaluate whether monitoring more than one biotic community provided additional information about a site's biological and environmental condition, we produced a two-taxon IBI that combined wet meadow zone vegetation and wetland-dependent songbird metrics. The two-taxon IBI had a marginally stronger linear relationship to the stress gradient (R2=0.72, p<0.001) than any single biotic community alone, although we argue that this added information would not warrant the extra cost, effort, and logistical barriers of sampling both plants and birds. The wet meadow zone vegetation and wetland-dependent songbird IBIs were strong surrogates of one another (R2=0.57), suggesting that wet meadow zone vegetation can be used to predict the health of wetland-dependent songbirds, and visa versa. Our results suggest that habitat for healthy wet meadow zone vegetation and wetland-dependent songbird communities is being degraded as compensation sites are replacing their natural analogs.

Anthropogenic disturbance affects the structure of bacterial communities

Patterns of taxa abundance distributions are the result of the combined effects of historical and biological processes and as such are central to ecology. It is accepted that a taxa abundance distribution for a given community of animals or plants following a perturbation will typically change in structure from one of high evenness to increasing dominance. Subsequently, such changes in evenness have been used as indicators of biological integrity and environmental assessment. Here, using replicated experimental treehole microcosms perturbed with different concentrations of the pollutant pentachlorophenol, we investigated whether changes in bacterial community structure would reflect the effects of anthropogenic stress in a similar manner to larger organisms. Community structure was visualized using rank-abundance plots fitted with linear regression models. The slopes of the regression models were used as a descriptive statistic of changes in evenness over time. Our findings showed that bacterial community structure reflected the impact and the recovery from an anthropogenic disturbance. In addition, the intensity of impact and the rate of recovery to pre-perturbation structure were dose-dependent. These properties of bacterial community structures may potentially provide a metric for environmental assessment and regulation.

Riverine invertebrate assemblages are degraded more by catchment urbanisation than by riparian deforestation

Summary1. Restoration of riparian forests has been promoted as a means of mitigating urban impacts on stream ecosystems. However, conventional urban stormwater drainage may diminish the beneficial effect of riparian forests.2. The relative effects of riparian deforestation and catchment urbanisation on stream ecosystems have rarely been discriminated because urban land use and riparian degradation usually covary. However, land use at three scales (channel canopy cover along a 100‐m site, riparian forest cover within 200 m of the channel for 1 km upstream, and catchment imperviousness) covaried only weakly along the lowland Yarra River, Victoria, Australia.3. We tested the extent to which each land use measure explained macroinvertebrate assemblage composition on woody debris and in the sediments of pools or runs in the mainstem Yarra River in autumn and spring 1998.4. Assemblage composition in both habitats and in both seasons was most strongly correlated with proportion of catchment covered by impervious surfaces. Sites with higher imperviousness had fewer sensitive taxa (those having a strong positive influence on indicators of biological integrity) and more taxa typical of degraded urban streams. Sensitive taxa rarely occurred in sites with &gt;4% total imperviousness. However, within sites of similar imperviousness, those with more riparian forest cover had more dipteran taxa. Channel canopy cover did not explain assemblage composition strongly.5. Riparian forest cover may influence richness of some macroinvertebrate taxa, but catchment urbanisation probably has a stronger effect on sensitive taxa. In catchments with even a small amount of conventionally drained urban land, riparian revegetation is unlikely to have an effect on indicators of stream biological integrity. Reducing the impacts of catchment urbanisation through dispersed, low‐impact drainage schemes is likely to be more effective.

Concordance of taxonomic richness patterns across multiple assemblages in lakes of the northeastern United States

We investigated the concordance of taxonomic richness patterns and their environmental correlates for assemblages of benthic macroinvertebrates, riparian birds, sedimentary diatoms, fish, planktonic crustaceans, and planktonic rotifers in 186 northeastern U.S. lakes. Taxon counts were standardized with respect to sampling effort using rarefaction. The degree of concordance among assemblage richness measures was low, but this was at least partly attributable to measurement precision. Aspects of lake morphology (area, depth) superseded other environmental features (climate, human development, water chemistry, nearshore physical habitat) as correlates of assemblage richness and were the strongest source of concordance. The benthic macroinvertebrates, birds, fish, and zooplankton all showed positive associations between richness and lake area. The diatoms showed negligible associations between richness and area and negative associations between richness and depth. Associations with human development were much weaker than with lake morphology and varied from positive (fish, planktonic crustaceans) to negative (diatoms). We conclude that taxonomic richness alone may be of ambiguous value as an indicator of biological integrity in lakes and that its natural drivers must be controlled for prior to assessing anthropogenic effects.

Concordance of taxonomic richness patterns across multiple assemblages in lakes of the northeastern United States

We investigated the concordance of taxonomic richness patterns and their environmental correlates for assemblages of benthic macroinvertebrates, riparian birds, sedimentary diatoms, fish, planktonic crustaceans, and planktonic rotifers in 186 northeastern U.S. lakes. Taxon counts were standardized with respect to sampling effort using rarefaction. The degree of concordance among assemblage richness measures was low, but this was at least partly attributable to measurement precision. Aspects of lake morphology (area, depth) superseded other environmental features (climate, human development, water chemistry, nearshore physical habitat) as correlates of assemblage richness and were the strongest source of concordance. The benthic macroinvertebrates, birds, fish, and zooplankton all showed positive associations between richness and lake area. The diatoms showed negligible associations between richness and area and negative associations between richness and depth. Associations with human development were much weaker than with lake morphology and varied from positive (fish, planktonic crustaceans) to negative (diatoms). We conclude that taxonomic richness alone may be of ambiguous value as an indicator of biological integrity in lakes and that its natural drivers must be controlled for prior to assessing anthropogenic effects. Resume : Nous avons etudie la concordance de profils de diversite taxonomique avec leurs correlats environnementaux chez des groupements de macroinvertebres benthiques, d'oiseaux de rivage, de diatomees sedimentaires, de poissons et de crustaces et de rotiferes planctoniques dans 186 lacs du nord-est des Etats-Unis. Nous avons normalise les

DEFINING AND RESTORING BIOLOGICAL INTEGRITYIN WILDERNESS LAKES

Restoring ecosystems to some previous “natural” state is often impeded by the lack of information on what goal is to be attained. However, a target for restoration of lake ecosystems can be established by developing a multimetric tool for the assessment of biological integrity. Our study identified a set of recurring responses to disturbance that indicate impaired biological integrity in lakes that include properties of species composition, taxonomic diversity, and functional organization of the lake communities. We then tested these hypothesized responses in 12 small, isolated Adirondack lakes impacted by nonnative fish species, from collections of fish, benthic invertebrates, zooplankton, and phytoplankton over a 3-yr period. We also tested the feasibility of restoring biological integrity through fish-community manipulation in three additional lakes utilizing these integrity indicators as a recovery target. Six indicators of biological integrity were sensitive to disturbance in Adirondack wilderness la...

Bird species assemblages as indicators of biological integrity in Great Basin rangeland

The study evaluates the potential for bird species assemblages to serve as indicators of biological integrity of rangelands in the Great Basin in much the same way that fish and invertebrate assemblages have been used as indicators in aquatic environments. Our approach was to identify metrics of the bird community using relatively simple sampling methods that reflect the degree of rangeland degradation and are consistent over a variety of vegetation types and geographic areas. We conducted the study in three range types (i.e., potential natural plant community types) in each of two widely separated areas of the Great Basin: south-eastern Idaho (sagebrush steppe range types) and west-central Utah (salt-desert shrub range types). Sites were selected in each range type to represent three levels of grazing impact, and in Idaho included sites modified for crested wheatgrass production. Birds were sampled by point counts on 9 100-m radius plots at 250-m spacing on each of 20 sites in each area during the breeding season. In sagebrush-steppe, 964 individuals in 8 species of passerine birds were used in analyses. Five metrics were significantly related to impact class, both when analyzed within range type and when analyzed with all range types combined. Species richness, relative abundance of shrub obligate species, and relative abundance of Brewer's sparrow were generally lower for the higher impact classes, whereas the reverse was true for dominance by a single species and for relative abundance of horned larks. In contrast, total number of individuals did not differ significantly as a function of impact class. In salt-desert shrub, a total of 843 birds in 4 species were included in analyses, 98% of which were horned larks. None of the metrics identified above was significantly related to impact class. Two metrics for breeding birds in sagebrush steppe (species richness and dominance) showed little overlap between values for the extremes of impact class, and thus they have potential as indicators of biological integrity. However, the sensitivity of these metrics appears to be greatest at the high impact end of the spectrum, which suggests they may have limited utility in distinguishing between sites having light and moderate impact.