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Reduction of sampling effort assessing macroinvertebrate assemblages for biomonitoring of rivers
Abstract
Biomonitoring methods based on macroinvertebrate assemblages are widely developed in streams and rivers. However, the use of invertebrates has been criticized due to the long time and expense of processing samples. Therefore, we evaluated the effectiveness of reducing the sampling effort from 20 to 5 samples to assess the stream macroinvertebrate community. In six streams in the Basque Country (North of Spain) 20 kick nets were collected following a multihabitat stratified sampling design. The macroinvertebrates were identified to family level and a smoothed family accumulation curve fitting the Clench function to the data was calculated for each stream. Richness was lower in 5 than in 20 samples. However, in general, the percentage of richness estimated with the subsampling may be considered representative of the existing taxa richness. Therefore, the study of five samples may be adequate for biomonitoring Basque streams, greatly minimizing time, effort and costs. RÉSUMÉ
... For example, Carlisle et al. (2008) showed that the macroinvertebrate model was the most precise compared to the diatom and fish models. However, the use of macroinvertebrates has been criticized due to long-time requirements and expensive costs of sampling, sorting, counting, and identifying them (De Bikuna et al., 2015) and this is likely to affect the effectiveness of biomonitoring protocols using macroinvertebrate communities (Pinna et al., 2014). ...
Streams and rivers cover a larger proportion of the Earth’s surface but are highly affected by human pressures. Conversely, bioassessment methods are in their infancy in developing countries such as Ethiopia. In this study, we compared 2- and 3-min macroinvertebrate kick samples at multiple locations for both riffle habitat (RH) and multihabitat (MH) approaches. The performance of each method was evaluated statistically using benthic macroinvertebrate metrics and diversity indices. Results of the Kruskal–Wallis analysis in this study showed no significant differences among methods tested in minimally impacted streams in Ethiopia and generally performed equally irrespective of the methods employed except for total abundances and Ephemeroptera abundances. Furthermore, multivariate analysis of the relative abundances of macroinvertebrate communities using analysis of similarity (ANOSIM), RELATE, non-metric multidimensional scaling (MDS), and classification strength-sampling method comparability (CS-SMC) indicated a high similarity in the macroinvertebrate communities recorded among all methods employed in this study area. However, the index of multivariate dispersion (IMD) test showed variations in relative abundances of macroinvertebrate communities among the methods. In summary, if the focus is not on rare taxa and the required information is not dependent on additional evidence provided by the use of lower taxonomic levels of identification (genus and species), the results of the present study support the use of the shorter 2-min RH kick sampling method for the bioassessment of wadeable rivers and streams in Ethiopia.
... Benthic macroinvertebrates were collected from undisturbed shallow runs and riffles using a Surber sampler (20 × 20 cm and 250 µm mesh net) and stored in plastic bottles containing 70% ethanol. We used eight replicates for each sampling site because this amount of sampling effort is considered sufficient to characterise macroinvertebrate communities (Gartzia De Bikuña et al. 2015). In the laboratory, benthic macroinvertebrates were counted and identified to family under a dissecting microscope. ...
The stress-gradient hypothesis predicts that biotic interactions within food webs are context dependent, since environmental stressors can attenuate consumer–prey interactions. Yet, how heavy metal pollution influences the impacts of predatory fish on ecosystem structure is unknown. This study was conducted in the Osor stream (Spain), which features a metal (mainly Zn) pollution gradient. We aimed to determine how the responses of benthic communities to the presence and absence of predatory fish interact with environmental stress and to test whether the top-down control of top predators is context dependent. To address these questions, periphyton biomass and macroinvertebrate densities were determined throughout an exclosure/enclosure mesocosm experiment using the Mediterranean barbel (Barbus meridionalis) as a top predator. The monitoring study showed that metal accumulation in periphyton and macroinvertebrates reflected patterns observed in water. The mesocosm study showed that fish predation effects on larval chironomids were not context-dependent and that periphyton biomass was markedly lower in the presence of fish regardless of metal pollution levels. This strong top-down control on periphytic algae was attributed to the foraging behaviour of fish causing bioturbation. In contrast, the top predator removal revealed grazer-periphyton interactions, which were mediated by heavy metal pollution. That is, periphyton benefitted from a lower grazing pressure in the metal-polluted sites. Together, our results suggest that the top–down control by fishes depends more on functional traits (e.g. feeding behaviour) than on feeding guild, and demonstrate the capacity of top predators to modify anthropogenic stressor effects on stream food-web structure.
... Benthic macroinvertebrates were collected from undisturbed shallow runs and riffles using a Surber sampler (20 × 20 cm and 250 µm mesh net) and were stored in plastic bottles containing 70% ethanol. We used eight replicates for each sampling site because this amount of sampling effort is considered sufficient to characterise macroinvertebrate communities (Gartzia De Bikuña et al. 2015). In the laboratory, benthic macroinvertebrates were counted and identified to family under a dissecting microscope. ...
Community structure and ecosystem functions are determined by physical and chemical conditions, food resources and biotic interactions. Mediterranean-climate streams are intrinsically variable in streamflow, with marked flow reduction in summer and floods in autumn and spring according to regional precipitation patterns. Riverine species are adapted to
cope with natural and predictable disturbances, and their responses are in a large part determined by their physiological and behavioral adaptations. As for fish, swimming performance can determine their ability to use habitats differing in water velocity, to obtain
food and avoid predation, etc. Today, the intense use of water by human demands causes longer low-flow periods in streams, thereby producing a certain degree of water stress. In addition, nutrient enrichment and water pollution are also common anthropogenic stressors that threaten ecological integrity of freshwater ecosystems. Metal pollution is of particular concern due to its high potential toxicity, perdurability and bioaccumulation through the food chain. At the bottom of the food chain, periphyton communities serve as food and energy sources for many organisms (e.g. macroinvertebrate grazers), so any stressor affecting periphyton is likely to indirectly affect organisms of a higher trophic level (“bottom-up control”). On the contrary,
periphytic algal biomass can be affected by shifts in grazing pressure, e.g. resulting from predator-induced changes in grazer density (“top-down control”). Periphyton communities are also involved in important ecosystem functions (e.g. nutrient cycling), and are important bioindicators for habitat degradation. Field mesocosm experiments, from which we can modify the density of certain consumers (e.g. fishes), have become an invaluable tool in ecotoxicology
and ecology for increasing mechanistic understanding of stressor effects.
This thesis aimed to assess the responses of stream biota to flow alterations, in terms of water velocity increments and reductions of discharge, and to metal pollution. The investigations performed encompassed (i) respirometry studies using swim-tunnel respirometers to evaluate swimming capabilities, as indicative of water velocity tolerance, and
physiological responses (energetic costs of swimming) of several freshwater fishes, as well as the drivers (morphological features) of variation within and among species; and (ii) field observational and mesocosm studies were carried out to evaluate the role of the threatened fish
B. meridionalis as modulator of the response of stream ecosystem structure and function to anthropogenic stressors, such as hydrologic alterations (e.g. resulting from the water diversion)
and metal pollution.
Our results showed that there exist a high intra-and interspecific variation in absolute critical swimming speed and metabolic traits in fish. Generally, swimming performance and aerobic metabolism scaled positively with body size. The study that compared the invasive mosquitofish (Gambusia holbrooki) with the native Spanish toothcarp (Aphanius iberus)
revealed that mosquitofish can swim faster (i.e. higher critical swimming speed) and more efficiently than Spanish toothcarp, as it showed lower cost of transport at a comparable workload. Both sexes of mosquitofish showed a better hydrodynamic body shape, i.e. streamlined body and thiner caudal peduncle, both of which were positively correlated with
swimming performance. The second study revealed that, after accounting for body size effects, critical swimming speed was independently affected by total length or maximal metabolic rate within certain fish species. At the interspecific level, variation in critical swimming speed was partly explained by the variation in the interrelated traits of maximal metabolic rate, and fineness and muscle ratios, when accounting for up to eight freshwater fish species.
Field observational and mesocosm studies showed that the top-down control by grazers was largely responsible for the variation in structural responses of periphyton, such as biomass and nutrient content, and in functional responses, such as nutrient uptake rates. Generally, when
grazer densities were higher the periphyton biomass (ash-free dry mass or chlorophyll-a) was lower, whereas the nitrogen content of periphyton increased (i.e. lower C:N). The higher phosphate uptake capacity by periphyton was likely due to a more rejuvenated and active periphyton community. In addition, the variation in macroinvertebrate and fish densities were
directly related to the impacts of natural (floods) and anthropogenic stressors. In metal-polluted reaches, we found that direct negative effects of metals on grazers led to indirect positive effects
on periphyton biomass.
Our studies also provided evidence about the important functional role of the Mediterranean barbel (Barbus meridionalis) in streams because shifts in their densities can lead to large ecosystem changes. The absence of this predatory fish triggered trophic-cascade responses on periphyton biomass in low impacted streams, and led to modify phosphate uptake rates by periphyton through biotic interactions. On the contrary, this benthic fish markedly reduced periphyton biomass via bioturbation impacts, and the greatest consumption effects on macroinvertebrates were found in larvae of Chironomidae.
Finally, it was discussed (i) the importance of fish swimming capabilities, metabolism and morphological traits in influencing patterns of species distributions in Mediterranean streams with hydrologic alterations; and (ii) the context dependency of stream community responses to anthropogenic stressors. A number of management actions and future research prospects in relation to our findings were also raised throughout this thesis.
... Taxonomic identification was basically carried out to the family level in accordance with Tachet et al. (2003). This family level has been often selected for practical biomonitoring of freshwater pollution and habitat degradation with benthic macroinvertebrates (Armitage et al., 1983;Rosenberg and Resh, 1993;Camargo et al., 2004;Ziglio et al., 2006;Alvial et al., 2012;Gartzia et al., 2015). After identification and counting, macroinvertebrate samples were dried in an oven at 60°C for 24 hours in order to estimate total biomass (dry-weight). ...
Inland trout farms can cause important adverse effects on freshwater communities due to the discharge of wastewater effluents into recipient rivers. In this research, responses of benthic macroinvertebrates to diminished water pollution downstream from a trout farm outlet were examined at spatial and temporal scales. Field studies were carried out in the Upper Tajuña River (Central Spain) during the springs of 2007 and 2015. Water pollution decreased, with increasing the downstream distance from the trout farm effluent, and also from 2007 to 2015 as a likely consequence of the lowered annual production of farmed rainbow trout following the 2008 economic recession. Reductions in water pollution resulted in increased concentrations of dissolved oxygen and decreased levels of turbidity and inorganic nutrients (ammonia and phosphate). Benthic macroinvertebrates responded positively to diminished water pollution by decreasing the relative abundance of collector-gatherers (oligochaetes and chironomids) and increasing the relative abundance of shredders and scrapers (ephemeropterans, plecopterans and trichopterans). In addition, values of taxonomic diversity and Biological Monitoring Water Quality biotic indices tended to increase. It is concluded that the wastewater treatment system of the trout farm should be improved to minimize the environmental impact on the recipient river.
This review presents the state-of-the-art of benthic soft-bodied algae as biondicators of
stream and river water quality, with emphasis on bioassessments set by the legislation
(e.g., European Water Framework Directive, USA Clean Water Act) to
promote the restoration and ensure ecological sustainability of water resources. The
advantages and shortcomings of a variety of bioassessment field and laboratory methods for
algae are discussed. The increasing use of soft-bodied algae in biotic indices to assess
individual anthropogenic stressors, and in multimetric indices of biotic integrity to
evaluate ecological condition in streams is summarized. Rapid microscopic and molecular
approaches for inferring nutrient supply with heterocystous cyanobacteria and other
sensitive algae are proposed. The need of better understanding of soft-bodied algae as
bioindicators is discussed and suggestions are made for obtaining meaningful bioassessment
information with cost-efficient efforts.
Information on both structure and function is essential to evaluate the ecological integrity of stream ecosystems and their response to natural and anthropogenic disturbance. Leaf-bags have been widely employed to assess stream ecosystem processes and the degree of leaf mass consumption has been proposed as one of the most useful functional descriptor in aquatic environments. However, the breakdown rate of leaves has been compared with structural indicators of macroinvertebrate assemblages derived from leaf-bags or from benthic samples, without any direct comparison on the characteristics of com -munities sampled with the two methods. The main objective of the paper is to conduct a comparative analysis of the structure, functional organization and biological traits of macroinvertebrate assemblages from artificial leaf packs and from benthic samples of a third-order stream in the Central Apennines (Italy). Of the 43 macroinvertebrate taxa globally found in our survey, 9 showed low ability or scarce attitude to colonize leaf-bags, while 6 rare taxa were exclusively sampled in artificial leaf packs. Both assemblages were characterized by the dominance of Chironomidae, though they were more abundant in leaf-bags (71% of total individuals collected) than in benthic samples (44%). Conversely, the mayfly Baetis sp. comprised more than 17% of total individuals collected with Surber nets and only 5% of leaf-bag assemblages. We found that compared to benthic assemblages, leaf-bag communities were less diversified with a lower richness and a lower number of Ephemeroptera, Trichoptera and Plecoptera (EPT) taxa; significant differences also emerged in assemblage composition. Contrary to what expected, artificial leaf packs resulted not particularly attractive for shredder organisms and were mainly colonized by collectors. Also the biological trait profiles of the leaf-bag community were significantly different from those shared by resident benthic taxa. Our findings could have profound implications in the assessment of the structural and functional integrity of stream ecosystems and in studies on freshwater biodiversity and ecosystem functioning. In these studies, the two methods (leaf-bags and Surber nets) should be regarded as complementary and not alternative.
Stream bioassessment studies usually use a single taxonomic group, most commonly fish or macroinvertebrates. However, differences in the life histories, habitat preferences, and physiological and behavioral traits of each assemblage may cause differences in their responses to environmental degradation. These factors can lead to discrepancies in overall assessments of ecological integrity. The Onondaga Lake Watershed (NY) has had a diverse history of pollution from multiple impacts, and the lake and several subsites are listed as USEPA Superfund sites. The response of fish and macroinvertebrate assemblages to environmental variables in the Onondaga Lake Watershed was assessed at 17 stream reaches in 2007, 2010, and 2011 using assemblage-specific metrics and indices of biotic integrity. Land use and substrate composition variables were significantly correlated (p < 0.05, r > |0.3|) with the first two macroinvertebrate PCA axes and were related to a downstream gradient of increased habitat degradation for the major tributaries. Water chemistry variables, canopy cover, and stream width were significantly correlated (p < 0.05, r > |0.3|) with the first two fish PCA axes. PCA axes for fish and macroinvertebrate assemblages were not significantly correlated, suggesting that the major environmental variables affecting fish and macroinvertebrate assemblages differed. Pearson correlations between the macroinvertebrate Biological Assessment Profile (BAP) and the fish Index of Biotic Integrity (IBI), and the macroinvertebrate Percent Model Affinity (PMA) and IBI were not significantly correlated. The macroinvertebrate metrics Percent Model Affinity (PMA) and BAP were positively and significantly correlated with Visual Habitat Assessment (VHA) scores, and the fish IBI was not significantly correlated with the VHA, further illustrating differences of fish and macroinvertebrates in their response to environmental variables. Results suggest that the use of multiple assemblages may be warranted for future assessments of stream quality and the development of effective monitoring programs in the Onondaga Lake Watershed.
The effectiveness and accuracy of biomonitoring programs, based on benthic macroinvertebrates, is strictly related to the sampling design and effort, whereas the feasibility depends on the economic sustainability of sample collection and processing methodologies. In the last decade, how to improve the Rapid Bioassessment Protocols (RBPs) maintaining the accuracy of the results has been a topic recurrently debated among researchers. It is well known that the sample unit size (i.e., surface of the sampled area, SUS) and the sieve mesh size (SMS), selected to collect and to retain benthic macroinvertebrates from soft-bottom samples, may affect the evaluation of the aquatic ecosystem ecological status; however, studies analyzing the combined influence of SUS and SMS on assessment tools are lacking, in particular for transitional water ecosystems. Even if the Water Framework Directive (WFD) suggests rapid and cost-effectiveness sampling effort and procedures, the identification of optimal SUS and SMS is a basic step to improve the RBPs and to meet WFD suggestions. Therefore, this research analyses the effects of four soft-bottom sample unit sizes (0.0225 m2, 0.0450 m2, 0.0675 m2, 0.0900 m2), and three sieve mesh sizes (4 mm2, 1 mm2, 0.25 mm2) on the selection of benthic macroinvertebrates and, thus, on assessment tools, in a Mediterranean lagoon. A sampling survey was performed in September 2009 at a perturbed and an unperturbed study site in the Lesina lagoon (SE Italian coastline); three replicates were taken for each SUS and SMS using an Ekman–Birge grab (15 cm × 15 cm). The samples were sieved on a column of three sieves, with decreasing mesh size. Benthic macroinvertebrates were sorted, identified, measured, weighted and included in twelve datasets (4 SUS × 3 SMS). Sampling effort (SE) was calculated for each SUS and SMS combination as: SE = [SUS m2 × (1/SMS mm2)] × 100. Four simple community descriptors (numerical density, taxonomic richness, biomass density, individual body-size) and four ecological indicators (AMBI, BENTIX, BITS, M-AMBI) were compared for each combination of SUS and SMS in both study sites. Simple community descriptors and ecological indicators varied significantly between perturbed and unperturbed study site. The results showed that SMS had significant effects on simple community descriptors and ecological indicators, except for BITS index. Conversely, no significant differences were observed for different SUS analyzing simple community descriptors and ecological indicators, except for taxonomic richness and M-AMBI index. The response of the ecological indicators was only slightly affected by the SMS, whereas SUS choice did not influence the ecological status assessment. Anyway, using the larger SMS (4 mm2), all ecological indicators showed either the same ecological quality status as the 1 mm2 and 0.25 mm2 SMS or, in some cases, one class higher, except for the AMBI index.
Assignment of values for natural ecological benefits and anthropocentric ecosystem services in riverine landscapes has been problematic, because a firm scientific basis linking these to the river's physical structure has been absent. We highlight some inherent problems in this process and suggest possible solutions on the basis of the hydrogeomorphic classification of rivers.We suggest this link can be useful in fair asset trading (mitigationand offsets), selection of sites for rehabilitation, cost-benefit decisions on incremental steps in restoring ecological functions, and general protection of rivers.
1 - The accurate evaluation of benthic macroinvertebrate taxonomic diversity in transitional water
ecosystems is strictly related to sampling effort and, usually, biomonitoring protocols define the
sampling effort needed to the elaboration of a specific ecological indicator. The time-lag between
the sampling event and the final assessment of ecological status, and to overall costs for sampling,
personnel and sample treatment suggest a reduction of sampling effort.
2 - How to simplify methods and to reduce efforts without compromising the ecological validity of
taxonomic diversity indicators is a topic recurrently debated in the procedures for sampling protocol
implementation. Regarding this topic, the identification of optimal sample unit size (SUS) and sieve
mesh size (SMS) is still lacking, mainly for benthic macroinvertebrates of Mediterranean transitional
water ecosystems.
3 - The present study analyzes the effect of the increasing the sampling effort in terms of sample unit size
(SUS; 0.0225 m2, 0.0450 m2, 0.0675 m2, 0.0900 m2) and sieve mesh size (SMS; 0.5 mm, 1 mm, 2 mm)
on the estimation of taxonomic diversity in a Mediterranean lagoon. Benthic macroinvertebrates were
collected in September 2009 at two locations, considering a perturbed and a relatively unperturbed
study site of Lesina lagoon (South-East Italy). Samples were sieved on a column of three decreasing
mesh sizes of sieves. Taxonomic richness (S), Shannon–Weaver index (H’), Simpson index (λ) and
Taxonomic distinctness (TD) were calculated for each study site, SUS and SMS combination, and
replicate. The difference between perturbed and relatively unperturbed site was tested according to
the variation of sampling effort using three-way ANOVA tests.
4 - As expected, the accuracy of the results increased with increasing of SUS and SMS, the difference
between perturbed and relatively unperturbed study site were always highlighted by each taxonomic
diversity index, independently by used SUS and SMS. The variation of taxonomic diversity indicators
seems to depend mainly by used sieve mesh size suggesting the reduction of sampling effort through
the reduction of sample unit size.
5 - Finally, this contribution could be useful in harmonizing sampling methodologies for the costeffectiveness
taxonomic diversity estimation and biomonitoring programs.
Running waters are perhaps the most impacted ecosystem on the planet as they have been the focus for human settlement and are heavily exploited for water supplies, irrigation, electricity generation, and waste disposal. Lotic systems also have an intimate contact with their catchments and so land-use alterations affect them directly. Here long-term trends in the factors that currently impact running waters are reviewed with the aim of predicting what the main threats to rivers will be in the year 2025. The main ultimate factors forcing change in running waters (ecosystem destruction, physical habitat and water chemistry alteration, and the direct addition or removal of species) stem from proximate influences from urbanization, industry, land-use change and water-course alterations. Any one river is likely to be subjected to several types of impact, and the management of impacts on lotic systems is complicated by numerous links between different forms of anthropogenic effect. Long-term trends for different impacts vary. Concentrations of chemical pollutants such as toxins and nutrients have increased in rivers in developed countries over the past century, with recent reductions for some pollutants (e.g. metals, organic toxicants, acidification), and continued increases in others (e.g. nutrients); there are no long-term chemical data for developing countries. Dam construction increased rapidly during the twentieth century, peaking in the 1970s, and the number of reservoirs has stabilized since this time, whereas the transfer of exotic species between lotic systems continues to increase. Hence, there have been some success stories in the attempts to reduce the impacts from anthropogenic impacts in developed nations. Improvements in the pH status of running waters should continue with lower sulphurous emissions, although emissions of nitrous oxides are set to continue under current legislation and will continue to contribute to acidification and nutrient loadings. Climate change also will impact running waters through alterations in hydrology and thermal regimes, although precise predictions are problematic; effects are likely to vary between regions and to operate alongside rather than override those from other impacts. Effects from climate change may be more extreme over longer time scales (>50 years). The overriding pressure on running water ecosystems up to 2025 will stem from the predicted increase in the human population, with concomitant increases in urban development, industry, agricultural activities and water abstraction, diversion and damming. Future degradation could be substantial and rapid (c. 10 years) and will be concentrated in those areas of the world where resources for conservation are most limited and knowledge of lotic ecosystems most incomplete; damage will centre on lowland rivers, which are also relatively poorly studied. Changes in management practices and public awareness do appear to be benefiting running water ecosystems in developed countries, and could underpin conservation strategies in developing countries if they were implemented in a relevant way.
1. In this study we used species accumulation models to solve one of the most serious problems encountered when comparing species richness between different communities. The problem is how to compare data among inventories in which different methodologies or measures of sampling effort have been employed. The methods used here for bats may be applied to any other biological group. We fit two asymptotic models to species accumulation curves for bat inventories to evaluate local or within‐community diversity (alpha) and landscape diversity (gamma) in central Veracruz, Mexico.
2. Species accumulation models allow us to: (i) measure within‐inventory efficacy and completeness; (ii) obtain an estimate of species richness that is based on a standardized measure of sampling effort, which makes valid comparisons between inventories possible; and (iii) estimate the minimum sampling effort required to reach a satisfactory level of completeness.
3. The applied models fit well in all cases ( r ² > 0·95). The linear dependence model predicted lower asymptotes and the Clench model predicted higher asymptotes than the observed species richness. These models are useful as predictors representing the lower and upper limits between which the true species richness value should lie.
4. Alpha diversity for bats in all vegetation communities (11–18 species) was lower than the gamma diversity (20 species), suggesting that species richness and the sampling effort required are related to environmental heterogeneity.
5. We propose that 90% of the total fauna predicted by either of the models is an acceptable standardized value for comparing species richness between communities.
6. We assessed the within‐inventory completeness as the proportion of the models’ asymptote, where 90% is the desired minimum level of completeness. Except in palm stands, all bat inventories had an acceptable level of completeness, at least for the linear dependence model.
7. For conditions similar to those of our study area, the minimum effort required to obtain a satisfactory level of completeness is 5–18 nights for plant communities and 18 nights for more heterogeneous landscapes.
8. We make recommendations for improving the efficacy and completeness of bat surveys based on the application of species accumulation models.
Multiple regression analysis was used to generate equations relating time required to sort and tabulate benthic invertebrates to size characteristics of benthic samples collected from a 5th-order river and a 3rd-order woodland stream. Number of invertebrates in a sample was the primary determinant of sample sorting time. Amount of detritus, occurrence of filamentous algae (Cladophora) and source stream contributed significant but minor additional variability to estimates (cumulativeR
2 = 0.95). When number of animals was excluded as a variable, amount of detritus and presence/absence ofCladophora alone could be used to predict sorting time (R
2 = 0.81). A typical sample containingCladophora required 29% longer to sort than samples containing equivalent amounts of organic material but noCladophora. The influence of sampler size and subsampling on processing and sorting time are considered. A general equation was derived to provide guidelines for selecting a size of stream sampler that subsequently minimizes total processing time required to estimate density of benthos with acceptable, constant precision. Overall sample processing and sorting time are reduced by using a smaller sampler or by subsampling only if benthic densities of animals are high. Use of regression equations to anticipate processing and sorting time required for a particular sampling program permits development of more efficient designs.
Thailand currently lacks formal bioassessment approaches and protocols to assist management decisions for water quality. The aim of this research is to develop a practical method of rapid bioassessment for a professional level by using benthic macroinvertebrate assemblages for streams in Thailand. Eleven reference and nine test sites were sampled in the headwater streams of the Loei River and adjacent areas to explore the development of a practical protocol. Specific physico-chemical parameters were selected to provide ecological information supplemental to the biological indicators. The biological research was designed around the USEPA Rapid Bioassessment Protocols (RBPs) using the multi-habitat approach. Four fixed-count subsamplings (100, 200, 300 and 500 organisms) were randomly conducted using a standardized gridded pan to evaluate an appropriate level for bioassessment in Thai streams. A 300 organism subsample is adequate for bioassessment purposes in Thai stream (evaluated by calculating dissimilarity values and ordination techniques). A systematic selection of candidate reference sites, metric selection, and index calibration was part of this research. Multimetric and multivariate analyses were examined as a foundation for bioassessment in Thailand. The multimetric approach appears to be more practical for a rapid bioassessment technique. Nine core metrics were identified for biological index score including number of total taxa, Diptera taxa, Ephemeroptera, Plecoptera, Trichoptera, and Coleoptera taxa, (%) Plecoptera, (%) Tolerant organisms, Beck's Biotic Index, (%) Intolerant organisms, Shredders taxa and Clingers taxa were calibrated for the final index. As a result of multimetric and multivariate analyses, family level identification data effectively discriminated reference condition and broad-scale environmental gradients. Hampered by incomplete taxonomic knowledge of benthic macroinvertebrates in Thailand, family-level identification may be sufficient taxonomic resolution for rapid bioassessment in Thailand.
Continental aquatic systems from rivers to the coastal zone are considered within two perspectives: (i) as a major link between the atmosphere, pedosphere, biosphere and oceans within the Earth system with its Holocene dynamics, and (ii) as water and aquatic biota resources progressively used and transformed by humans. Human pressures have now reached a state where the continental aquatic systems can no longer be considered as being controlled by only Earth system processes, thus defining a new era, the Anthropocene. Riverine changes, now observed at the global scale, are described through a first set of syndromes (flood regulation, fragmentation, sediment imbalance, neo-arheism, salinization, chemical contamination, acidification, eutrophication and microbial contamination) with their related causes and symptoms. These syndromes have direct influences on water uses, either positive or negative. They also modify some Earth system key functions such as sediment, water, nutrient and carbon balances, greenhouse gas emissions and aquatic biodiversity. Evolution of river syndromes over the past 2000 years is complex: it depends upon the stages of regional human development and on natural conditions, as illustrated here for the chemical contamination syndrome. River damming, eutrophication and generalized decrease of river flow due to irrigation are some of the other global features of river changes. Future management of river systems should also consider these long-term impacts on the Earth system.
Aquatic insects and other benthic invertebrates are the most widely used organisms in freshwater biomonitoring of human impact. Because of the high monetary investment in freshwater management, decisions are often based on biomonitoring results, and a critical and comparative review of different approaches is required. We used 12 criteria that should be fulfilled by an "ideal" biomonitoring tool, addressing the rationale, implementation, and performance of a method. After illustrating how the century-old but still widely used Saprobian system does not meet these criteria, we apply them to nine recent approaches that range from the suborganismal to the ecosystem level. Although significant progress has been made in the field, no recent approach meets all 12 criteria. Given that the use of biomonitoring information has important financial consequences, we suggest that societies and governments prioritize how these criteria should be ranked.
Species richness is a fundamental measurement of community and regional diversity, and it underlies many ecological models and conservation strategies. In spite of its importance, ecologists have not always appreciated the effects of abundance and sampling effort on richness measures and comparisons. We survey a series of common pitfalls in quantifying and comparing taxon richness. These pitfalls can be largely avoided by using accumulation and rarefaction curves, which may be based on either individuals or samples. These taxon sampling curves contain the basic information for valid richness comparisons, including category–subcategory ratios (species-to-genus and species-to-individual ratios). Rarefaction methods – both sample-based and individual-based – allow for meaningful standardization and comparison of datasets. Standardizing data sets by area or sampling effort may produce very different results compared to standardizing by number of individuals collected, and it is not always clear which measure of diversity is more appropriate. Asymptotic richness estimators provide lower-bound estimates for taxon-rich groups such as tropical arthropods, in which observed richness rarely reaches an asymptote, despite intensive sampling. Recent examples of diversity studies of tropical trees, stream invertebrates, and herbaceous plants emphasize the importance of carefully quantifying species richness using taxon sampling curves.
NOTE: This is not a book, contrary to what ResearchGate claims. This is a software application and User's Guide. The current version is Version 9. The citations here are incomplete, since each version has its own citations. EstimateS currently has more than 4000 citations in the peer-reviewed literature. For the full list, go to GoogleScholar: http://bit.ly/11YdUlg .
Rapid bioassessment protocols for use in streams and wadeable rivers: periphyton, benthic macroinvertebrates, and fish Developments in aquatic insect biomonitoring: a comparative analysis of recent approaches
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Invertébrés d'eau douce: systéma-tique, biologie et écologie, CNRS : Paris, 587 p Linking ecosystem services, rehabilitation, and river hydrogeomorphol-ogy
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