Differences In Macroinvertebrate Communities Research Articles

Agricultural Runoff Effects on Leaf Litter Decomposition: A Comparative Study in Natural and Constructed Deltaic Mediterranean Wetlands

Wetlands, widely distributed and hotspots of biodiversity, play a crucial role in global biogeochemical cycles and human well-being. However, despite their ecological importance, wetlands worldwide are under threat due to widespread conversion into agricultural fields, leading to changes in hydrology, increased salinity, and more frequent eutrophication. In response to these challenges, constructed wetlands are created to treat agricultural wastewater and mitigate eutrophication. This study aims to assess the effect of natural vs. constructed wetlands on ecosystem functioning (organic matter decomposition of the dominant vegetation: Phragmites australis and Typha angustifolia). We conducted this study in the Ebro River Delta (NE Spain), which represents a deltaic wetland affected by agricultural land-use changes, examining two constructed and two natural wetlands. Our findings indicate that the influence of agricultural runoff on the decomposition process was similar in both types of wetlands, suggesting that freshwater agricultural runoff has a consistent effect on ecosystem functioning, regardless of its origin, natural vs. constructed. Differences in macroinvertebrate communities associated with leaf litter were likely due to specific conductivity but did not impact decomposition rates. The estimated time required to decompose 95% of the T. angustifolia litter produced annually in the studied wetlands ranged from 288 to 856 days. In constructed wetland, this decomposition time exceeded one year, contributing to soil formation and carbon sequestration in wetland ecosystems. Our study suggests that the utilization of constructed wetlands for treating agricultural runoff can aid in mitigating the impacts of agricultural land use in these areas.

Bioassessment of Macroinvertebrate Communities Influenced by Gradients of Human Activities.

This study explores the impact of anthropogenic land use changes on the macroinvertebrate community structure in the streams of the Cangshan Mountains. Through field collections of macroinvertebrates, measurement of water environments, and delineation of riparian zone land use in eight streams, we analyzed the relationship between land use types, stream water environments, and macroinvertebrate diversities. The results demonstrate urban land use type and water temperature are the key environmental factors driving the differences in macroinvertebrate communities up-, mid-, and downstream. The disturbed streams had lower aquatic biodiversity than those in their natural state, showing a decrease in disturbance-sensitive aquatic insect taxa and a more similar community structure. In the natural woodland area, species distributions may be constrained by watershed segmentation and present more complex community characteristics.

Macroinvertebrate communities characteristics and their responses to fluvial geomorphological feature of typical debris flow gullies in the Xiaojiang River Basin, Yunnan Province

云南小江流域为典型干热河谷区，该区域干热少雨，流域内泥石流沟众多，生态环境十分脆弱.2017年4月和9月对小江流域的吊嘎河、蒋家沟、蓝泥坪沟、清水沟、陶家小河5条泥石流沟及小江干流开展了系统调查，旨在摸清5条泥石流沟及小江干流河流地貌、水环境及底栖动物群落现状，分析不同河床结构发育程度的泥石流沟间的底栖动物群落差异，揭示底栖动物对反映河床结构发育程度的河流地貌特征参数凹凸度的响应关系.调查期间于5条泥石流沟及小江干流中共采集到底栖动物70种，隶属于4门6纲38科69属，其中环节动物6种，软体动物2种，节肢动物61种，扁形动物1种.从种类类群来看，5条泥石流沟及小江干流的底栖动物物种数、密度、生物量上均以节肢动物占绝对优势，分别占总量的78.0%~92.5%、98.7%~100%、65.0%~100%.从功能摄食类群上来看，5条泥石流沟及小江干流底栖动物密度上均以直接收集者为主，占总量的74.3%~96.3%.回归分析表明，5条泥石流沟中底栖动物物种数、密度及生物量均与河流地貌特征参数凹凸度呈正相关关系，由此可见，发育良好的河床结构在维持河流地貌稳定和改善河流生态方面起着举足轻重的作用.本研究结果可为小江流域山区河流泥石流沟河床结构重建及生态修复提供科学依据.;The Xiaojiang River Basin is a typical dry-hot valley area, characterized by high temperatures, little rain and many debris flow gullies, where ecological environment is very fragile. In April and September of 2017, field surveys were conducted in the five debris flow gullies (i.e., the Diaoga Creek, the Jiangjia Creek, the Lanniping Creek, the Qingshui Creek, and the Taojiaxiaohe Creek) and the Xiaojiang River. The purpose of this study is to understand fluvial geomorphological feature, water environment, and macroinvertebrate communities in the five debris flow gullies and the Xiaojiang River, to analyze the differences in macroinvertebrate communities among debris flow gullies with different riverbed structures, and to reveal the responses of macroinvertebrates to the fluvial geomorphological parameter (degree of concavity-convexity) reflecting the development degree of riverbed structure. A total of 70 taxa of macroinvertebrates were identified, belonging to 4 phyla, 6 classes, 38 families and 69 genera. With regard to the taxonomic groups, arthropods were dominant in the species richness, density, and biomass of macroinvertebrates in the five debris flow gullies and the Xiaojiang River, accounting for 78.0%-92.5%, 98.7%-100.0% and 65.0%-100.0% of the total richness, densities, and biomass, respectively. With regard to the functional feeding groups, collector-gatherers were all dominated in the five debris flow gullies and the Xiaojiang River, accounting for 74.3%-96.3% of the total densities. Regression analyses showed that the species number, density, and biomass of macroinvertebrates were all positively correlated with the fluvial geomorphological parameter (degree of concavity-convexity) of the five debris flow gullies. The present study indicated that the well-developed riverbed structure plays an important role in maintaining the stability of the fluvial geomorphology and ecological quality. The results of this study can provide scientific basis for riverbed structure reconstruction and ecological restoration of debris flow gullies in mountain regions of the Xiaojiang River Basin.

Basin risk explains patterns of macroinvertebrate community differences across small streams in the Fayetteville Shale, AR

Understanding the relationship between natural landscape characteristics and human activities is crucial to predicting conditions under which loss of freshwater biodiversity occurs. For example, region-specific human activities, like unconventional natural gas (UNG) development, are often absent from models because of their limited spatial extent, yet their effects may alter stream ecosystems. Unconventional natural gas development is an expanding human activity that requires land-clearing, water withdrawal, and chemicals for hydraulic fracturing that could alter stream habitat and water quality, yet the degree of alteration may depend on basin natural landscape characteristics. We modified a basin-specific multi-metric risk model and used it to predict differences in macroinvertebrate communities in small stream basins (range 5.71–90.96 km2) in the Fayetteville Shale, Arkansas. We modeled basin risk as the interaction between basin natural sensitivity to alterations and basin exposure to human activities. We predicted that macroinvertebrate communities in 18 basins exposed to a gradient of unconventional natural gas (UNG) in a pasture-dominated landscape would experience greater differences in macroinvertebrate metrics across a risk gradient than 22 basins with a similar gradient of pasture land. Macroinvertebrate metrics of diversity declined by as much as 88% across the basin risk gradient. In contrast, macroinvertebrate metrics of biomass and density increased by 28% across the same basin risk gradient. Basin risk explained more variation in macroinvertebrate communities than sensitivity or exposure alone, suggesting an interaction between basin natural landscape characteristics and human activities. In contrast to our prediction, all macroinvertebrate metrics responded similarly in basins with and without UNG, which suggests either there was no added stressor-effect of UNG or UNG alterations resulted in the same biological effects as pasture. However, macroinvertebrate metrics in basins with and without UNG responded differently across a sediment-specific risk model where dams were modeled as sediment traps instead of structures that alter flow and temperature. As land alterations continue in the Fayetteville Shale, our basin-specific risk model can be used as a tool to identify at-risk stream communities.

An inter-catchment assessment of macroinvertebrate communities across groundwater-fed streams within Denali National Park, interior Alaska

Groundwater-fed streams are typically hotspots of aquatic biodiversity within glacierized catchments. Surface water physicochemistry and macroinvertebrate communities within five groundwater-fed streams were characterised across catchments in Denali National Park, interior Alaska. The main aim of this study was to assess whether hydrological controls on macroinvertebrate communities (e.g. flow permanence) identified within previous catchment-specific studies are present at wider spatial scales, across multiple groundwater-fed streams located on alluvial terraces within glacierized catchments. Macroinvertebrate community diversity, in general, was shown to be high and relatively invariant across the groundwater-fed streams assessed. Flow permanence was shown to be responsible for the greatest differences in macroinvertebrate communities. Although ephemeral and perennial streams exhibited no differences in diversity, perennial streams maintained higher total abundance and taxonomic richness of macroinvertebrates than ephemeral streams. Furthermore, macroinvertebrate community structure was also shown to be different, with ephemeral streams composed of a smaller number of specialised taxa able to withstand disturbance from periodic dewatering. Relationships between physicochemical variables and macroinvertebrate diversity, however were not observed across the catchments. The high diversity and structural heterogeneity of macroinvertebrate communities observed across alluvial terrace streams indicated the importance of these systems as biodiversity hotspots in regions under threat from climate change.

Effects of hydrological regime, landscape features, and environment on macroinvertebrates in St. Lawrence River wetlands

Wetlands of a large fluvial lake in the St. Lawrence River (Quebec, Canada) were visited during 3 years (2004–2006) to collect macroinvertebrates across the belt of emergent vegetation. We tested the hypothesis that hydrology, river landscape, and local environment would explain variations in macroinvertebrates. The 66 taxa collected lake-wide comprised a few abundant but widespread groups (Malacostraca, Oligochaeta, Chironomidae, and Mollusca). Between 2004 and 2006, total abundance at 5 sites monitored annually fell by one order of magnitude, and taxa richness decreased from 19 to 12 taxa. Proportion of amphipods (Gammaridae) dropped sixfold whereas proportion of annelids (Oligochaetes) rose ninefold. The impoverishment of macroinvertebrates coincided with low summer water levels in 2005 and 2006, resulting in the periodic emersion of up-slope sites. Spatial differences in macroinvertebrate communities were less important than inter-annual differences, owing to large variability among sites. Patterns in macroinvertebrate communities were related to water depth, vegetation, and local changes in sediments (31% of variance explained). Gammaridae (Malacostraca) were strongly associated with down-slope sites, whereas Oligochaeta (Annelida) dominated in up-slope sites. Inter-annual changes in water level had major effects on macroinvertebrate communities in Lake Saint-Pierre, above and beyond other environmental variables.

A Landscape‐Based Regionalization of Natural Flow Regimes in the Ebro River Basin and Its Biological Validation

AbstractFlow prediction in ungauged basins is an important task for water resources planning and management, and remains a fundamental challenge for hydroecological research. Based on a previous classification of streams and rivers in the Ebro River basin (Spain), where six natural flow‐regime types were identified, we apply a new predictive approach of the flow regime type based on climatic and physiographic descriptors. We used a set of easily available environmental variables as discriminant parameters: annual precipitation, annual evapotranspiration, annual air temperature, elevation, catchment area, drainage density and geology. A stepwise landscape‐based classification procedure consisting of several stepwise discriminant analyses and canonical discriminant analyses allocated a set of sites with poor or no natural flow data into the flow types defined. Misclassification rates obtained by cross‐validation ranged between 1.12% and 11.9%. Additionally, the ecological soundness of the proposed regionalization was tested by the concordance between macroinvertebrate communities and the proposed classification using NMDS and ANOSIM. NMDS resulted in a clear separation of sites into five NFR classes with available macroinvertebrate data, and ANOSIM found significant differences in macroinvertebrate communities among classes. Copyright © 2014 John Wiley & Sons, Ltd.

Transitional and freshwater bioassessments: One site, two perspectives?

The freshwater–saltwater-transition-zone was analysed using two different sampling protocols and assessment methodologies, developed for freshwater and estuaries, to compare their agreement level in terms of community composition and quality assessments. The use of different protocols resulted in significant differences in macroinvertebrate communities, in index scores and initially in quality classes. After modifications in the sensitivity scores of the IBMWP and AMBI indices (average scores or the use of a score of the other index when both were present), the differences were largely reduced and quality classes became coincident for the assessments provided by IPtIs and BAT tools. Such harmonisation of quality assessments for adjacent water categories (e.g., large rivers vs. transitional waters), exemplified here as an harmonisation in one of the metrics comprised in the assessment tools, is essential as it has direct implications on the expansion and accomplishment of River Basin Management Plans committed by the Water Framework Directive.

English

This study aimed to investigate changes in macroinvertebrate assemblage within Nyando wetlands and developed an index of biotic integrity for monitoring human disturbances. Triplicate macroinvertebrate samples were collected monthly for seven months using a scoop net. They were sorted live, counted and identified to genus level. Water samples for nutrients were collected and analyzed using standard methods. Physico-chemical parameters were taken in situ using electronic meters. Macroinvertebrates were analyzed for richness, diversity, dominance and abundance. Abundance was correlated with physico-chemical parameters. Kruskal-Wallis test was used to test spatial differences in macroinvertebrate community. Metrics for index of biotic integrity were chosen, tested, and a 5, 3, 1 scoring criteria was used. A total of 45 genera were identified and Kruskal-Wallis test analysis revealed significant spatial differences in macroinvertebrate abundance.  Repeated measures ANOVA showed significant spatio-temporal differences. Tolerant macroinvertebrates were abundant at the disturbed sites whereas intolerant taxa showed a strong negative correlation with nutrient levels. Sites with higher disturbance recorded a total index score far below the reference site score. The results indicated that macroinvertebrates in Nyando wetlands can be used to monitor its ecological integrity. The IBI developed should be used to protect the lake from eutrophication.   Key words: Human disturbance, water quality, index of biotic integrity.

Landuse Effects on Cirhanyobowa River Water Quality in D.R. Congo

Cirhanyobowa River in D.R. Congo, is extensively used as washing and drinking water source by surrounding population as well as by gorillas. The study was carried out in three sites on Cirhanyobowa River to evaluate the effect of landuse (forest, mining and agricultural) on Cirhanyobwa River water quality. Surface water temperature, DO, BOD 5, nitrogen and phosphorus were measured, and aquatic macroinvertebrates collected monthly for a period of one year and measured according to standards analytical and biological methods. Results have shown changes in water quality for the forest, mining and agricultural sites but slight changes in number of taxa at the forested and mining sites with respectively 43 and 42 species; and significant changes in agricultural site with 27 species. Chemical and physical parameters measured at the three sites did not seem sufficient to account for all observed differences in macroinvertebrate communities, suggesting some unmeasured toxicity. It was established that there is water quality deterioration along Cirhanyobwa River due to surrounding population anthropogenic activities.

INFLUENCE OF ENVIRONMENTAL INSTABILITY OF GROUNDWATER‐FED STREAMS ON HYPORHEIC FAUNA, ON A GLACIAL FLOODPLAIN, DENALI NATIONAL PARK, ALASKA

ABSTRACTMacroinvertebrate community distributions were investigated within the benthic and hyporheic zone of five groundwater‐fed streams, on a floodplain terrace, in a glacierized catchment in Alaska, in summer 2008. The streams were characterized by a distinct gradient in environmental instability and provided an opportunity to determine whether the local variability in environmental instability of groundwater‐fed streams (reflecting differences in lengths of groundwater flow pathways) are of sufficient magnitude and frequency to influence macroinvertebrate community distribution. Individual measures of surface‐water temperature, streamflow, streambed stability and sediment size were incorporated into a multivariate index of environmental instability (IEI), using principal components analysis. In the hyporheic zone, a logarithmic association was observed between macroinvertebrate diversity and IEI and a quadratic association between abundance and IEI. The increase in diversity along the gradient of instability reflected a greater evenness of taxa caused by reduction in abundance of Chironomidae, combined with an increase in abundance of several less dominant taxa (Limnephilidae, Empididae, Baetidae and Simuliidae). At the surface, a quadratic association between diversity and IEI was observed, consistent with the intermediate disturbance hypothesis.Chironomidae, Nemouridae and Empididae presented contrasting surface and hyporheic distributions, indicating use of the hyporheic zone as a refuge. Moreover, covariance in the surface and hyporheic distribution of Limnephilidae and Chloroperlidae suggested the use of the hyporheic zone as an extension of the benthic habitat. The data indicate that local variability in environmental conditions between groundwater‐fed streams is sufficient to induce differences in macroinvertebrate communities and in the response of individual taxa. Copyright © 2012 John Wiley & Sons, Ltd.

Macroinvertebrates as indicators of fish absence in naturally fishless lakes

Abstract1. Little is known about native communities in naturally fishless lakes in eastern North America, a region where fish stocking has led to a decline in these habitats.2. Our study objectives were to: (i) characterise and compare macroinvertebrate communities in fishless lakes found in two biophysical regions of Maine (U.S.A.): kettle lakes in the eastern lowlands and foothills and headwater lakes in the central and western mountains; (ii) identify unique attributes of fishless lake macroinvertebrate communities compared to lakes with fish and (iii) develop a method to efficiently identify fishless lakes when thorough fish surveys are not possible.3. We quantified macroinvertebrate community structure in the two physiographic fishless lake types (n = 8 kettle lakes; n = 8 headwater lakes) with submerged light traps and sweep nets. We also compared fishless lake macroinvertebrate communities to those in fish‐containing lakes (n = 18) of similar size, location and maximum depth. We used non‐metric multidimensional scaling to assess differences in community structure and t‐tests for taxon‐specific comparisons between lakes.4. Few differences in macroinvertebrate communities between the two physiographic fishless lake types were apparent. Fishless and fish‐containing lakes had numerous differences in macroinvertebrate community structure, abundance, taxonomic composition and species richness. Fish presence or absence was a stronger determinant of community structure in our study than differences in physical conditions relating to lake origin and physiography.5. Communities in fishless lakes were more speciose and abundant than in fish‐containing lakes, especially taxa that are large, active and free‐swimming. Families differing in abundance and taxonomic composition included Notonectidae, Corixidae, Gyrinidae, Dytiscidae, Aeshnidae, Libellulidae and Chaoboridae.6. We identified six taxa unique to fishless lakes that are robust indicators of fish absence: Graphoderus liberus, Hesperocorixa spp., Dineutus spp., Chaoborus americanus, Notonecta insulata and Callicorixa spp. These taxa are collected most effectively with submerged light traps.7. Naturally fishless lakes warrant conservation, because they provide habitat for a unique suite of organisms that thrive in the absence of fish predation.

Exploring differences in macroinvertebrate communities from emergent, floating-leaved and submersed vegetation in shallow ponds

An important driver of biodiversity is habitat structural complexity: more complex habitats generally contain more species. A good measure of habitat complexity therefore could be a strong tool to predict habitat biodiversity. In this pilot study, we test the significance of the classification of aquatic macrophytes that have similar complexity and shape into vegetation types (Emergent: Phragmites, Typha; Floating-Leaved Nymphaeidae: Nuphar; Submersed: Potamogeton, Utricularia) to explain macroinvertebrate community structure. Macroinvertebrate abundance and family richness increased from floating-leaved Nuphar to emergent and submersed vegetation. Family richness corrected for abundance did not differ among the vegetation types, possibly due to the small subsamples, but larger stands of Nuphar were needed to reach similar total richness. Six families that significantly differentiated between the vegetation types were associated with submersed and emergent vegetation. Vegetation type explained ∼21 % of the variation in macroinvertebrate community structure within a pond, and performed better than any other classification of macrophyte species in explaining variation. Thus, if these results stand generalization in space and time, vegetation type can be a fast and practical indicator of a pond's invertebrate density, and probably diversity.

Macroinvertebrate 13C variability analysis for the assessment of lake trophic functioning

The aim of this study was to better understand the relationships of within- and among-lake variability of macroinvertebrate carbon stable-isotope ratios with both lake trophic potential and lake trophic functioning. Two approaches based on the macroinvertebrate communities were undertaken on 11 French lakes: the Lake Biotic Index (LBI), a lake biological quality assessment method (Verneaux et al. 2004 a), and the carbon isotopic signatures of macroinvertebrates expressed by metrics of dispersion (standard deviation of the littoral macroinvertebrate mean δ 13 C values and differences between littoral and deep mean δ 13 C values (Δδ 13 C)). The littoral macroinvertebrate mean δ 13 C values obtained ranged from -11.7%o to -38.6‰. This great among-lake variability can be partially explained by different geological substrata on which the lakes are located and, potentially, by the lake organic matter recycling activity. Moreover, the depth-related differences in macroinvertebrate community δ 13 C (Δδ 13 C values) or macroinvertebrate taxa (taxon 13 C depletion: TΔδ 13 C) were highly correlated to the values of a LBI sub-index, which was itself correlated to hypolimnion oxygenation and deep sediment organic matter contents. This result suggests that the studied lakes showed various degrees of deep recycled carbon assimilation. The depth-related macroinvertebrate 13 C depletion may then be considered as describing the result of lake trophic functioning. However, because no correlation was observed between littoral macroinvertebrate δ 13 C variability and lake trophic potential, it seemed difficult to conclude as to the influence of different carbon sources on this potential.

Multi‐scale assessment of macroinvertebrate richness and composition in Mediterranean‐climate rivers

Summary1. Similar constraints in distant, but climatically comparable, regions may be expected to yield biotic assemblages with similar attributes. Environmental factors that constrain communities at smaller scales, however, may be different between climatically similar regions. Thus, patterns observed at large scales may differ from those detected at small scales, and international comparisons should be focussed at multiple scales.2. Mediterranean‐climate regions (MCRs) are characterized by remarkable seasonal variability in precipitation and temperature. Accordingly, rivers in these regions have seasonal and predictable floods and droughts, and temporary reaches are frequent. Present in six geographical regions of the world, MCRs have similar environmental constraints and are ideal for testing intercontinental similarities between macroinvertebrate communities.3. We examined aquatic macroinvertebrate taxon richness and composition in MCRs at three scales: regional, reach and macrohabitat. At the regional scale, the Mediterranean Basin had the highest taxon richness at family level, and southwestern Australia the lowest. Taxonomic composition showed c. 85% similarity between the northern hemisphere MCRs of California and the Mediterranean Basin, which were followed in similarity by South Africa. The two Australian MCRs (South west and South) showed a similarity to each other of about 70% whereas the Chilean fauna was the most distinct.4. At the reach scale, taxon richness was not significantly different between permanent and temporary reaches in any MCR, whereas taxonomic composition was significantly different among northern hemisphere MCRs. At the macrohabitat scale, taxon richness was not significantly different between lotic and lentic macrohabitats within any of the MCRs, but differences in macroinvertebrate communities were found between macrohabitats when considering regions.5. Our results show that the strength of similarity between distant but climatically similar regions is scale‐dependent, being highest at the macrohabitat scale. Although the similarities in richness and composition at the macrohabitat scale are presumed to be universal, the seasonal predictability of drought in MCRs is expected to result in characteristic macroinvertebrate responses at the reach scale. We suggest, however, that regional evolutionary history and environmental characteristics may override this general pattern of a similar response of MCRs at different scales. The Mediterranean Basin and California, having similar historical and environmental condition, thus appeared as the most similar MCRs at all scales.

The Distribution of Benthic and Hyporheic Macroinvertebrates from the Heads and Tails of Riffles

The spatial distribution of benthic (up to 0.05 m depth) and hyporheic (0.25 and 0.5 m depth) macroinvertebrates from downwelling zones at the heads of riffles and upwelling zones at the tails of riffles was examined in two studies on a 4th order chalk stream in Dorset, England. In the first study, differences in benthic and hyporheic macroinvertebrate community composition between the head and tail of a single riffle were investigated. In the second study, a replicated design involving eight riffles was used to compare benthic and hyporheic macroinvertebrate community composition both between heads and tails of the same riffles and between riffles. In the first (single riffle) study there were significantly higher mean numbers of benthic invertebrates and families at the riffle head (715 individuals and 13.8 families per 0.0225 m2) compared to the tail (192 individuals and 8.7 families). ANOSIM analysis also showed that the community structure of head and tail benthic samples was significantly different. In the second (replicated riffle) study, there were also significantly more benthic invertebrates at riffle heads (\(\bar{x}\) = 594 per 0.0225 m2) compared to tails (\(\bar{x}\) = 417 per 0.0225 m2), although this was not the case for families, and community structure also differed significantly between riffle heads and tails. In contrast, in the hyporheic zone, there were no significant differences between the total numbers of invertebrates in the riffle heads and tails, or between riffles, although a significant difference in family richness between riffle head and tail samples was identified in the first study. Community analysis revealed progressively poorer separation of riffle head and tail samples at 0.25 m and 0.5 m hyporheic depths. Whilst being able to identify clear differences in benthic communities from riffles heads and tails, the physically heterogeneous nature of the riffle habitats studied made it difficult to account for the consistent differences in macroinvertebrate communities observed with the physical variables measured.

Evaluating regional differences in macroinvertebrate communities from forested depressional wetlands across eastern and central North America

AbstractForested depressional wetlands are an important seasonal wetland type across eastern and central North America. Macroinvertebrates are crucial ecosystem components of most forested depressional wetlands, but community compositions can vary widely across the region. We evaluated variation in macroinvertebrate faunas across eastern and central North America using 5 published taxa lists from forested depressional wetlands in Michigan, Ontario, Wisconsin, Florida, and Georgia. We supplemented those data with quantitative community descriptions generated from 17 forested depressional wetlands in South Carolina and 74 of these wetlands in Minnesota. Cluster analysis of presence/absence data from these 7 locations indicated that distinct macroinvertebrate communities existed in northern and southern areas. Taxa characteristic of northern forested depressional wetlands included Sphaeriidae, Lumbriculidae, Lymnaeidae, Physidae, Limnephilidae, Chirocephalidae, and Hirudinea (Glossophoniidae and/or Erpodbell...

Macroinvertebrate and zooplankton responses to emergent plant production in upper Mississippi River floodplain wetlands

The upper Mississippi River is managed as a multiple use system, balancing the needs of industry, recreation, and navigation. Through water-level management (WLM), the U. S. Army Corps of Engineers manipulates water levels in some navigation pools to promote emergent vegetation for fish and wildlife in off-channel habitats. A manipulative experiment was conducted to assess responses of invertebrates to vegetation and associated organic matter associated with WLM in floodplain wetlands of Mississippi River navigation pool 25. Macroinvertebrate and zooplankton communities and benthic organic matter were compared in replicated paired plots consisting of experimentally de-vegetated and adjacent control plots. Hydrology was variable during the study, resulting in a strong vegetation response year (1999), a no response year (2000), and a moderate response year (2001). Differences in benthic organic matter between plot types were most pronounced in fall 2000, following the strong vegetation response year, where residual vegetation resulted in significantly higher total and coarse benthic organic matter in vegetated plots. Of the 2 years (2000, 2001) they were sampled, differences in macroinvertebrate communities were only evident in 2001 when there was a moderate vegetation response. Total macroinvertebrate densities during 2001 were similar between devegetated and vegetated plots, but responses of individual taxa varied. Total macroinvertebrate biomass was significantly higher in the vegetated plots during 2001. Of dominant groups, Oligochaeta biomass was significantly higher in vegetated plots, whereas total Chironomidae abundance and biomass were both significantly higher in devegetated plots. Community metrics reflected higher macroinvertebrate diversity in vegetated plots. Zooplankton were not abundant or diverse in plots, but total densities were significantly higher in vegetated plots during the 1999 strongest vegetation response year. Results demonstrate that WLM to enhance emergent vegetation in off-channel habitats of this large river influences organic matter dynamics and invertebrates. Although many groups responded positively to vegetation, responses varied with the degree of vegetation response and the taxonomic resolution of analyses, suggesting that hydrologic variability, and associated spatial and temporal variability in emergent vegetation, can enhance invertebrate diversity in floodplain wetland habitats.

Spatial differences in macroinvertebrate communities in intertidal seagrass habitats and unvegetated sediment in three New Zealand estuaries

This study investigated macroinvertebrate community composition in seagrass beds at a range of spatial scales, with an emphasis on the transition between vegetated and unvegetated sediment. At four intertidal sites in three New Zealand estuaries (Whangamata, Wharekawa, and Whangapoua Harbours), a large continuous bed of seagrass (Zostera capricorni) was selected with adjacent unvegetated sediment. Macroinvertebrate community composition and biomass, as well as sediment characteristics, were determined at sampling locations 1 and 50 m inside seagrass beds, and 1, 10, and 50 m outside seagrass beds. Analysis of univariate measures of community composition (total abundance, number of species, and diversity) and total biomass indicated significant differences among sites and sampling locations, but contrary to many previous studies these measures were not higher inside than outside the seagrass beds. Multivariate analysis indicated that sites with high seagrass biomass supported a similar community composition. The remaining sampling locations were clustered by site, but there were also significant differences in community composition among sampling locations within a site. There were distinctive communities at the edge of seagrass beds at sites with high seagrass biomass, and evidence that the effects of seagrass beds may extend into the unvegetated sediment. At the low seagrass biomass site there was no evidence of any edge effects, although community composition differed inside and outside the bed. Differences in community composition were driven primarily by small changes in the relative abundance of the dominant taxa. At high seagrass biomass sites the absence of deep-burrowing polychaetes and low numbers of bivalves suggests that one possible mechanism underlying the observed variation in community composition was inhibition by the dense root-rhizome mat. The results of this study emphasize the need to consider the linkages between habitats in heterogeneous estuarine landscapes and how those linkages vary among sites, if the structure and functioning of macroinvertebrate communities in seagrass habitats are to be understood.

Impacts of golf courses on macroinvertebrate community structure in Precambrian shield streams.

The influence of golf course operation on benthic macroinvertebrate communities in Precambrian Shield streams was evaluated using rapid bioassessment and the reference condition approach. Streams were sampled for water chemistry and invertebrates in 1999 and 2000, six on operational golf courses, and seven in forested reference locations. Correspondence analysis (CA) was used to determine the major patterns in the macroinvertebrate taxa, and canonical correspondence analysis (CCA) was used to evaluate relationships with environmental variables. The reference streams were used to define the normal range of variation for a variety of summary indices to evaluate the golf course streams. In all cases, golf course streams were higher in nutrients and dissolved ions and more alkaline than the forested reference streams. There was considerable variability in the macroinvertebrate fauna from the golf course streams, which was related to differences in golf course land management practices and to the potential influence of highway runoff. Of the management practices evaluated, fertilizer application rates in particular were important, as was the presence of ponds upstream on the course. Invertebrate taxa with higher abundances in golf course streams included Turbellaria, Isopoda, Amphipoda, Zygoptera, and Trombidiformes. Taxa more common in the reference streams included Ephemeroptera, Megaloptera, Culicidae, and Plecoptera. There were marked differences in the overall benthic macroinvertebrate community in three of the six golf course streams studied relative to the forested reference streams, suggesting that golf course land management on the Precambrian Shield can be associated with significant differences in macroinvertebrate community structure.