Comparison between electrofishing and snorkeling surveys to describe fish assemblages in Laurentian streams

We evaluated the relative performance of electrofishing and visual surveys (snorkeling) for estimating the abundance of combinations of fish species and size classes in rivers. We also assessed the effect of environmental conditions on potential differences between the results obtained using these two sampling methods. Sampling sites were distributed in the Laurentian region of Québec. Both methods were used while sections were blocked. Three snorkelers swam the river sections upstream while identifying and counting fish of each species and size classes. Three-pass electrofishing was performed in the same sites and abundances were estimated with a maximum likelihood depletion model. Greater abundances of fish were observed by snorkeling than by electrofishing at all sites. Snorkeling species richness was higher or equal to electrofishing richness in, respectively, 60 % and 40 % of sampled sites. Differences in the fish communities observed by both sampling methods were not related to environmental conditions. The results of our work are therefore contrary to that of most published studies that suggested the use of electrofishing over visual surveys. This study highlights that conclusions derived from previous work on sampling gear comparisons may not be generalisable; rather survey methods might benefit from being selected based on fish community composition.     

Monitoring fish communities in wadeable lowland streams: comparing the efficiency of electrofishing methods at contrasting fish assemblages

Electrofishing is considered a reliable tool to assess the assemblages and biodiversity of fish in wadeable streams. The most widely used electrofishing techniques (point [P], single-pass [S-P], and multiple-pass [M-P]) vary as to the effort needed for sample collection, and this may potentially influence the degree of accuracy. Moreover, little is known about the comparability of the methods and their specific performance in streams with different fish assemblages. The aim of this investigation was to validate (using M-P sampling as reference) the use of P and S-P electrofishing techniques to accurately assess the richness, density and size distribution of fishes in small streams at both regional and global scale independently of fish assemblages and geographical region. We sampled 50-m-long reaches in a total of 33 lowland stream reaches that were located in different climatic and biogeographical regions (Uruguay and Denmark) and hosted different fish assemblages. Subtropical fish communities exhibited higher richness (Uy: 12–32, Dk: 1–9) and densities (Uy: 1.3–5.2, DK: 0.1–4.9 in. m^?2) than temperate streams. We applied both "global models" using the entire database (33 sites) and "local models" including the same number of sites but using the climatic region as a model variable. Regression analyses revealed that the P, S-P and M-P methods all provided an adequate picture of the species composition and size distribution, and transfer equations for comparison between methods are thus not required. Conversely, richness was better predicted by S-P and by P techniques for regional and global models, respectively. Transfer equations obtained for abundance revealed that the P and S-P models can accurately transform catch data into M-P estimations. The transfer equations provided here may have great relevance as they allow relatively reliable comparisons to be made between data obtained by different techniques. We also show that less intensive sampling techniques may be equally useful for monitoring purposes as those requiring more intensive efforts (and costs). We encourage validation of our developed transfer equations on data from other regions of the world.     

Fish abundances in shoreline habitats and submerged aquatic vegetation in a tidal freshwater embayment of the Potomac River

Submerged aquatic vegetation (SAV) is considered an important habitat for juvenile and small forage fish species, but many long-term recruitment surveys do not effectively monitor fish communities in SAV. To better understand the impact of recent large increases of SAV on the fish community in tidal freshwater reaches of the Potomac River, we compared traditional seine sampling from shore with drop ring sampling of SAV beds (primarily Hydrilla) in a shallow water (depths, <1.5 m) embayment, Gunston Cove. To accomplish this, we developed species-specific catch efficiency values for the seine gear and calculated area-based density in both shoreline and SAV habitats in late summer of three different years (2007, 2008, and 2009). For the dominant species (Fundulus diaphanus, Lepomis macrochirus, Etheostoma olmstedi, Morone americana, Lepomis gibbosus, and Fundulus heteroclitus), density was nearly always higher in SAV, but overall, species richness was highest in shoreline habitats sampled with seines. Although historical monitoring of fish in Gunston Cove (and throughout Chesapeake Bay) is based upon seine sampling (and trawl sampling in deeper areas), the high densities of fish and larger areal extent of SAV indicated that complementary sampling of SAV habitats would produce more accurate trends in abundances of common species. Because drop ring samples cover much less area than seines and may miss rare species, a combination of methods that includes seine sampling is needed for biodiversity assessment. The resurgence of SAV in tidal freshwater signifies improving water quality, and methods we evaluated here support improved inferences about population trends and fish community structure as indicators of ecosystem condition.     

Effect of diel period and season on seining effort required to detect changes in Lake Erie beach fish assemblages

Using beach seining data from Lake Erie beaches, we examined the effect of diel period and season on two common study objectives considered sensitive to sampling effort: (1) has fish assemblage composition changed between two sampling time periods?, and (2) how many samples are necessary to provide a representative sample of the fish assemblage? Across a range of effect sizes and power levels, sample sizes were estimated for species richness, total fish abundance, round goby (Neogobius melanostomus) abundance and emerald shiner (Notropis atherinoides) abundance. For most sampling periods and effect sizes, several hundred to several thousand seine hauls were estimated to be required for detecting large-scale (e.g. basin-wide) changes in round goby and emerald shiner abundance. Depending on the indicator of interest, night seining (either spring or fall) was interpreted as the most efficient approach. For both seasons, sampling effort beyond 40 to 50 night seine hauls results in few additional species being detected. Both species accumulation curves and estimated sample sizes indicate that less effort is required to detect species richness changes than fish abundance. For most effect sizes and power levels, estimates of the number of seine hauls required to detect changes in fish abundance are unrealistically large for most monitoring programs. More practical monitoring strategies could be achieved by adopting alternative indicators (e.g. guilds), a more liberal significance level (p=0.1), a paired-site sampling design, or including reference sites.     

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.     

应用鱼类完整性指数F-IBI评价巢湖流域的主要河流健康

保护河流健康是河流生态管理的重要目标,鱼类对维护河流生态系统健康的作用重要且不可替代。依据2013年10月巢湖53个河流采样点的鱼类调查数据,采用假设参照值法构建鱼类生物完整性指数(F-IBI)的参照系统,进而评价河流健康状况。基于29个候选生物参数,通过参数与环境因子间的相关性分析、参数间的冗余分析及其分布范围分析,确定F-IBI由鱼类总物种数、鲤科鱼类物种数百分比、中下层鱼类物种数百分比、肉食性鱼类数量百分比、产粘性卵鱼类数量百分比和耐受性鱼类数量百分比等6个参数构成。利用比值法统一各参数量纲,F-IBI值即为各构成参数比值的累加,进而评价河流水生态健康的等级,其中亚健康的采样点占16.98%,健康状况一般的采样点占50.94%,健康状况较差的采样点占32.08%。此外,影响巢湖主要河流F-IBI的重要水环境变量是叶绿素a。对重点污染区域,修复水生态系统和制定科学合理的策略,是恢复巢湖流域生态健康的重要手段。     

Chronic genetic damages in <Emphasis Type="Italic">Geophagus brasiliensis</Emphasis> exposed to anthropic impact in Estuarine Lakes at Santa Catarina Coast–Southern of Brazil

Biological monitoring through animals exposed to pollutants using biomarkers provides a promising tool for the identification of pollutants that may cause damage to human health and/or to sustainability of ecosystems. The effects of pollutants in fish tissues are important tools to understand the impact of human activities in natural ecosystems. The aim of this work was to study the water quality of two estuarine lakes in Santa Catarina, Brazil (Camacho Lake and Santa Marta Lake). Geophagus brasiliensis is a species widely distributed in Brazil and was used in this work. Comet assays in peripheral red blood and kidney cells, micronucleus tests in peripheral red blood cells, measurements of acetylcholinesterase activity in axial muscle and histopathological analysis of liver were used as biomarkers. Three sampling campaigns were undertaken in November 2004, June 2005 and November 2005. Thirty adult animals were sampled from each of three different sites (P1—Santa Marta Lake, P2 and P3—Camacho Lake). A negative control was sampled in a non-polluted site at Costa Ecological Park, Paraná. The positive control for genotoxicity was obtained by treating animals with copper sulphate. The results showed that both studied lakes are impacted by potential genotoxic substances. Severe lesions in liver of G. brasiliensis were also observed. The inhibition of acetylcholinesterase activity suggests the presence of pesticides or metals in the studied sites. This work shows that the water quality of Santa Marta and Camacho Lakes have been compromised and further control source of pollutants into these ecosystems is required.     

The effects of subsampling and sampling frequency on the use of surface-floating pupal exuviae to measure Chironomidae (Diptera) communities in wadeable temperate streams

Community, diversity, and biological index metrics for chironomid surface-floating pupal exuviae (SFPE) were assessed at different subsample sizes and sampling frequencies from wadeable streams in Minnesota (USA). Timed collections of SFPE were made using a biweekly sampling interval in groundwater-dominated (GWD) and surface-water-dominated (SWD) streams. These two types of stream were sampled because they support different Chironomidae communities with different phenologies which could necessitate sampling methodologies specific to each stream type. A subsample size of 300 individuals was sufficient to collect on average 85% of total taxa richness and to estimate most metrics with an error of about 1% relative to 1,000 count samples. SWD streams required larger subsample sizes to achieve similar estimates of taxa richness and metric error compared to GWD streams, but these differences were not large enough to recommend different subsampling methods for these stream types. Analysis of sample timing determined that 97% of emergence occurred from April through September. We recommend in studies where estimation of winter emergence is not important that sampling be limited to this period. Sampling frequency also affected the proportion of the community collected. To maximize the portion of the community, collected samples should be taken across seasons although no specific sampling interval is recommended. Subsampling and sampling frequency was also assessed simultaneously. When using a 300-count subsample, a 4-week sampling interval from April through September was required to collect on average 71% of the community. Due to differences in elements of the chironomid community evaluated by different studies (e.g., biological condition, phenology, and taxonomic composition), richness estimates are documented for five sampling intervals (2, 4, 6, 8, 10, and 12 weeks) and five subsample sizes (100, 200, 300, 500, and 1,000 counts). This research will enhance future studies by providing guidelines for tailoring SFPE methods to study specific goals and resources.     

Survey design for lakes and reservoirs in the United States to assess contaminants in fish tissue

The National Lake Fish Tissue Study (NLFTS) was the first survey of fish contamination in lakes and reservoirs in the 48 conterminous states based on a probability survey design. This study included the largest set (268) of persistent, bioaccumulative, and toxic (PBT) chemicals ever studied in predator and bottom-dwelling fish species. The U.S. Environmental Protection Agency (USEPA) implemented the study in cooperation with states, tribal nations, and other federal agencies, with field collection occurring at 500 lakes and reservoirs over a four-year period (2000–2003). The sampled lakes and reservoirs were selected using a spatially balanced unequal probability survey design from 270,761 lake objects in USEPA’s River Reach File Version 3 (RF3). The survey design selected 900 lake objects, with a reserve sample of 900, equally distributed across six lake area categories. A total of 1,001 lake objects were evaluated to identify 500 lake objects that met the study’s definition of a lake and could be accessed for sampling. Based on the 1,001 evaluated lakes, it was estimated that a target population of 147,343 (±7% with 95% confidence) lakes and reservoirs met the NLFTS definition of a lake. Of the estimated 147,343 target lakes, 47% were estimated not to be sampleable either due to landowner access denial (35%) or due to physical barriers (12%). It was estimated that a sampled population of 78,664 (±12% with 95% confidence) lakes met the NLFTS lake definition, had either predator or bottom-dwelling fish present, and could be sampled.     

Spatial and temporal distribution of macrobenthos in different mangrove ecosystems of Tamil Nadu Coast, India

This paper deals with the spatial distribution and diversity of macrobenthos and their relationships between physico-chemical parameters of the water and sediment in different mangrove habitats of Tamil Nadu, India during different seasons (2008). Among the different ecosystems of mangrove benthic faunal assemblages, macrofauna species number, density, richness, and Shannon-Wiener index were the highest and the Simpson dominance index was medial at riverine mangrove community. However, the Pielou Evenness index of riverine mangrove community was slightly lower than other communities. The similarities among the macrobenthic communities at different sampling sites were determined using Bray-Curtis similarity coefficient and ordinations of non-metric multidimensional scaling (MDS). Thirty-one species were recorded in developing (16 polychaetes, six bivalves, seven gastropods, and two crustaceans), 35 species were recorded in riverine (20 polychaetes, six bivalves, five gastropods, and four crustaceans) and 31 species were recorded in island mangrove ecosystem (19 polychaetes, four bivalves, five gastropods, and three crustaceans). Among the three ecosystems, a total of 46 benthic macrofauna consisting of 27 species of polychaetes, eight species of gastropods, seven species of bivalves, and four species of crustaceans were recorded. However, there were obvious differences among the community structures in the three mangrove habitats. This result implied that the different mangrove ecosystem had different effects on the macrofauna communities and shed light on the macrofauna adaptation capability to specific habitats.     

Ecological assessment of French Atlantic lakes based on phytoplankton, phytobenthos and macrophytes

Biological elements, including phytoplankton, phytobenthos, macrophytes, benthic invertebrates and fish, are employed by the EU Water Framework Directive (WFD) 2000/60/EC as ecological indicators for the assessment of surface waters. The use of primary producers (phytoplankton, phytobenthos and macrophytes) for water quality assessment has a long history, and several methods have been developed worldwide. In this study, we used these three communities to assess the ecological status of five natural lakes located in the Aquitaine region (southwest France). Several biological indices used in lakes from other European countries or in French rivers were employed and compared among the three communities. Each primary producer provided complementary information about the ecological status of the lakes, including the invasiveness of exotic taxa. Regardless of the producer community used, the response to the environment, as reflected by the indices (adequate for each community), was similar: Lakes Cazaux, Lacanau and Hourtin showed the best ecological status and Parentis and Soustons the worst. Phytoplankton diagnosis reflected and integrated unambiguously the water quality of the lakes, as demonstrated by the strong relationships between the phytoplankton index and the trophic status criteria. This community appeared as the best indicator, especially when macrophytes were absent. The methods applied here represent a potential tool for the assessment of the ecological status in the context of WFD, but they need to be refined. We propose modifications for phytobenthos index initially tailored for running waters for adequate use in lentic ecosystems. Indices for the three primary producers should be modified to incorporate exotic species which may provide information on potential biodiversity losses.     

Function Approximation and Documentation of Sampling Data Using Artificial Neural Networks

Biodiversity studies in ecology often begin with the fitting and documentation of sampling data. This study is conducted to make function approximation on sampling data and to document the sampling information using artificial neural network algorithms, based on the invertebrate data sampled in the irrigated rice field.Three types of sampling data, i.e., the curve species richness vs. the sample size, the curve rarefaction, and the curve mean abundance of newly sampled species vs.the sample size, are fitted and documented using BP (Backpropagation) network and RBF (Radial Basis Function) network. As the comparisons, The Arrhenius model, and rarefaction model, and power function are tested for their ability to fit these data. The results show that the BP network and RBF network fit the data better than these models with smaller errors.BP network and RBF network can fit non-linear functions (sampling data) with specified accuracy and don't require mathematical assumptions. In addition to the interpolation, BP network is used to extrapolate the functions and the asymptote of the sampling data can be drawn. BP network cost a longer time to train the network and the results are always less stable compared to the RBF network. RBF network require more neurons to fit functions and generally it may not be used to extrapolate the functions. The mathematical function for sampling data can be exactly fitted using artificial neural network algorithms by adjusting the desired accuracy and maximum iterations. The total numbers of functional species of invertebrates in the tropical irrigated rice field are extrapolated as 140 to 149 using trained BP network, which are similar to the observed richness.     

Relationships among nekton assemblage structure and abiotic conditions in three Texas tidal streams

The objective of this study was to assess the effects of spatially and temporally varying abiotic conditions on the nekton residing in tidally influenced streams and determine the comparability of the assemblage response across the various gears needed to fully characterize the biota. Three tidal streams were sampled seasonally for 2 years for chemical (physiochemical profiles), physical (in-stream and riparian habitat classification), and biological (nekton sampled with bag seines, trawls, and gill nets) components of ecosystem integrity. Multiple sampling stations on each stream encompassed the transitional character of the tidally influenced ecosystem, from the freshwater of the river to the saltwater of the bay. Instead of characterizing the biota with traditional fish-based indexes of biotic integrity, analysis methodologies relying heavily on multivariate ordination techniques were used. This study showed that the temporal and spatial relationships among nekton assemblages and abiotic environmental conditions were quite gear dependent. The greatest degree of difference in indicators of ecosystem health all involved upstream–downstream gradients that appear to be driven by salinity structure. Based on the results of this study, dissolved oxygen concentration does not appear to be a major structuring factor in the physical, chemical, or biological component of ecosystem integrity.     

Estimating vertebrate,benthic macroinvertebrate,and diatom taxa richness in raftable Pacific Northwest rivers for bioassessment purposes

The number of sites sampled must be considered when determining the effort necessary for adequately assessing taxa richness in an ecosystem for bioassessment purposes; however, there have been few studies concerning the number of sites necessary for bioassessment of large rivers. We evaluated the effect of sample size (i.e., number of sites) necessary to collect vertebrate (fish and aquatic amphibians), macroinvertebrate, and diatom taxa from seven large rivers in Oregon and Washington, USA during the summers of 2006–2008. We used Monte Carlo simulation to determine the number of sites needed to collect 90–95% of the taxa 75–95% of the time from 20 randomly located sites on each river. The river wetted widths varied from 27.8 to 126.0 m, mean substrate size varied from 1 to 10 cm, and mainstem distances sampled varied from 87 to 254 km. We sampled vertebrates at each site (i.e., 50 times the mean wetted channel width) by nearshore-raft electrofishing. We sampled benthic macroinvertebrates nearshore through the use of a 500-μm mesh kick net at 11 systematic stations. From each site composite sample, we identified a target of 500 macroinvertebrate individuals to the lowest possible taxon, usually genus. We sampled benthic diatoms nearshore at the same 11 stations from a 12-cm² area. At each station, we sucked diatoms from soft substrate into a 60-ml syringe or brushed them off a rock and rinsed them with river water into the same jar. We counted a minimum of 600 valves at 1,000× magnification for each site. We collected 120–211 diatom taxa, 98–128 macroinvertebrate taxa, and 14–33 vertebrate species per river. To collect 90-95% of the taxa 75-95% of the time that were collected at 20 sites, it was necessary to sample 11–16 randomly distributed sites for vertebrates, 13–17 sites for macroinvertebrates, and 16–18 sites for diatoms. We conclude that 12–16 randomly distributed sites are needed for cost-efficient sampling of vertebrate richness in the main stems of our study rivers, but 20 sites markedly underestimates the species richness of benthic macroinvertebrates and diatoms in those rivers.     

Assessing changes in the Presque Isle Bay watershed fish community using a modified index of biotic integrity: before and after the elimination of combined sewer overflows

An index of biotic integrity and species richness were used to assess changes in the Presque Isle Bay watershed fish community before and after the elimination of combined sewer overflows (CSOs). The fish community was sampled with a backpack electrofisher in 2011 at 12 stream locations on 4 tributaries of Presque Isle Bay, Erie County, Pennsylvania. All sites were previously sampled in 2001. Significant increases in species richness and index of biotic integrity (IBI) scores were observed in 2011 compared to 2001. The significant increases in species richness and IBI scores occurred following the elimination of 10 CSOs to Garrison Run, 7 CSOs to Cascade Creek, and 37 CSOs to Mill Creek. Despite the increased richness and IBI scores, the fish community remains in poor condition, which may be related to the highly urbanized land use of the watershed. Urban land uses comprise 77 % of the Presque Isle Bay watershed, and in both 2011 and 2001, the watershed as a whole did not meet warm-water habitat criteria. It is unlikely that the fish community will continue to recover without addressing urbanization throughout the watershed.     

Maryland Biological Stream Survey: A State Agency Program to Assess the Impact of Anthropogenic Stresses on Stream Habitat Quality and Biota

The Maryland Department of Natural Resources is conducting the Maryland Biological Stream Survey, a probability-based sampling program, stratified by river basin and stream order, to assess water quality, physical habitat, and biological conditions in first through third order, non-tidal streams. These streams comprise about 90% of all lotic water miles in the state. About 300 sites (75 m segments) are being sampled during spring and summer each year. All basins in the state will be sampled over a three-year period, 1995-97. MBSS developments in 1995-96 included (1) an electrofishing capture efficiency correction method to improve the accuracy of fish population estimates, (2) two indices of biotic integrity (IBI) for fish assemblages to identify degraded streams, and (3) land use information for catchments upstream of sampled sites to investigate associations between stream condition and anthropogenic stresses. Based on fish IBI scores at 270 stream sites in six basins sampled in 1995, 11% of non-tidal stream miles in Maryland were classified as very poor, 15% as poor, 24% as fair, and 27% as good. IBIs have not yet been developed for stream sites with catchment areas less than 120 hectares (23% of non-tidal stream miles). IBI scores declined with stream acid neutralizing capacity (ANC) and pH, an association that was also evident for fish species richness, biomass, and density. Low IBI scores were associated with several measures of degraded stream habitat, but not with local riparian buffer width. There was a significant negative association between IBI scores and urban land use upstream of sampled sites in the only extensively urbanized basin assessed in 1995. Future plans for the MBSS include (1) identifying all benthic macroinvertebrate samples to genus, (2) developing benthic macroinvertebrate, herpetofaunal, and physical habitat indicators, and (3) enhancing the analysis of stream condition-stressor associations by refining landscape metrics and using multi-variate techniques.     

A Critical Analysis of Illinois’ Fish Mercury Monitoring Program, 1974–1998

Mercury contamination in fish is a serious public health concern that contrasts with other health benefits of eating fish. Like most US states, Illinois has monitored fish mercury contamination for decades to warn the public of mercury exposure risks by consuming fish. Has this monitoring program been effective in detecting public mercury exposure risks? I analyzed fish mercury contamination data from Illinois inland lakes (1974–1998; >?2,300 samples, 18 fish species, 149 lakes) and found that: (a) sampling and analyses have been severely limited since 1985; (b) sampling effort varied widely among lakes and species, and (c) trends and spatial patterns were confused by this variability. As a result of a severely limited and nonstrategic monitoring program, public mercury exposure risks via Illinois fish consumption remain unclear, despite much effort over many years. Illinois monitors fewer fish per angler than many US states, but is not alone in this regard. Illinois should resurrect and redesign its fish contaminant monitoring program to one that strategically and systematically assesses human mercury exposure risk. Other US states and nations may also benefit from similar retrospective examinations of monitoring programs intended to protect public health.     

Effects of subsample size on seasonal and spatial comparisons of stream macroinvertebrate communities

We examined the effect of subsample size on the accuracy of information obtained from aquatic macroinvertebrate assemblage samples. Subsamples containing 100 organisms or 300 organisms were compared on the bases of processing time and the ability to discern ecological differences among samples. Independently of subsample size, assemblages differed between study streams, primarily reflecting an intermittent vs. permanent stream difference, and between seasons at most streams. It required, on average, two additional hours to process the larger subsamples. Larger subsamples gave significantly higher estimates of total richness and Ephemeroptera, Plecoptera, and Trichoptera (EPT) richness, but the relative abundances of many assemblage subsets (e.g., EPT organisms and most functional feeding groups) were similar using both subsample sizes. Larger subsamples did not typically enhance the ability to discriminate between samples from different seasons, but did more accurately distinguish among streams when differences were subtle. They also appeared to avoid Type I error in comparisons of compositionally similar reaches within a study stream.     

Development of a Pollination Service Measurement (PSM) method using potted plant phytometry

The value of pollination to human society is not limited to agricultural production, but also in the sustainability of ecosystems and the services that they provide. Seed set can be used as a comparative measure of pollination effectiveness, with minimum variability expected when other resources are not limiting. Six species of self-incompatible fall asters (Symphyotrichum) were used to evaluate pollination service at 12 sites across a spectrum of expected levels of pollination. Seed set per inflorescence was generally lower at sites with lower pollinator numbers and diversity, although as expected pollinator assemblage characteristics were highly variable within and between sites. However, rankings of sites showed consistency of response across phytometer species and between years; the summed ranks across multiple species appears to have as the greatest value in Pollination Service Measurement (PSM). Abundance, richness, and Shannon diversity of pollinator assemblages were highly autocorrelated and showed variable relationships with seed set depending on plant species and temporal scale of pollinator assemblage assessment. Use of seed set to directly measure pollination service at a site was consistent and cost effective when compared to less certain and more labour-intensive methods of pollinator collection and identification, and shows promise for implementation in pollination monitoring and bioassessment practices.