A major developmental defect observed in several Biscayne Bay,Florida, fish species

Synopsis Stunted or missing dorsal spines or rays, sometimes accompanied by a depression in the dorsal profile, were found in 10 fish species in six families from North Biscayne Bay. The same morphological abnormality occurred inHaemulon sciurus, H. parrai, H. plumieri, Lagodon rhomboides, Archosargus rhomboidalis, Diplodus argenteus, Lutjanus griseus, Kyphosus sectatrix, Sphoeroides testudineus, andLactrophyrys quadricornis. Another morphological abnormality, scale disorientation, was found in six species:H. parrai, L. rhomboides, A. rhomboidalis, L. griseus, andAbudefduf saxatilis. Pugheadedness, jaw deformities, and other abnormalities also were observed. The occurrence of similar deformities across such a spectrum of fishes from the same location suggests the deformity was induced by something in the environment common to all these species. Although there could be other explanations for the unusual cluster of abnormalities, it is suspected that the same environmental contaminant or group of contaminants is adversely affecting a common developmental pathway of these fishes. Biscayne Bay is an urban estuary that receives agricultural, industrial, and residential run off.     

Characterization of Scale Abnormalities in Pinfish, Lagodon rhomboides, from Biscayne Bay, Florida

Correlations between marine habitat degradation and the prevalence of abnormalities and diseases in populations can provide a starting point for understanding the effects of changes in environmental conditions on marine organisms. The present study characterized the features of scale disorientation (SD), a common morphological anomaly encountered in pinfish, Lagodon rhomboides, in Biscayne Bay, Florida (U.S.A.). Scale disorientation consisted of discrete patches of scales rotated dorsally or ventrally away from the normal scale position without any projection of the scales outwards from the body surface. The direction of scale growth within the patches varied from normal to a minor misalignment to a complete reversal of direction. The severity of SD, defined as the percentage of body surface area affected, varied from 1 to 34% with a mean of 9.3%. Affected fish monitored in the laboratory demonstrated a proportional growth of SD areas such that the percentage of body surface affected did not change as the fish grew. Scale disorientation was more prevalent in the northern region of the bay, an area known to be more contaminated. Scales from SD areas exhibited significantly abnormal morphology with larger average focus diameter, smaller size, more elongate shape and fewer radii relative to normal scales. Experimental removal of scales demonstrated that normal scales regrew in normal orientation and morphology while those from SD areas regrew in abnormal orientations and morphologies. Experiments in which fish were exposed to acute and chronic injuries indicated that these physical traumas were insufficient to directly induce formation of scale disorientations typical of those seen in the wild. Observations of pinfish in the laboratory revealed that SD areas can appear spontaneously in normal juvenile and adult fish. These new SD areas developed relatively rapidly, did not require prior scale loss and remained stable in size after first appearance. Although the etiology of SD remains unknown, the significant difference in prevalence of this syndrome between regions of Biscayne Bay having different levels of sediment contaminants suggests that environmental factors may be important in development of SD.     

Phytoplankton and zooplankton as indicators of water quality in Discovery Bay,Jamaica

Several investigations exist which use planktonic communities as indicators of water quality in Jamaican and Caribbean Bays, however, few are conducted before there are obvious effects of eutrophication. Therefore, most of our ‘baseline’ data are for bays already severely affected by pollution. This study was conducted to assess water quality in Discovery Bay, Jamaica, before there were severe signs of eutrophication. The bay was monitored over a 12-month period (October 1995–September 1996) using 10 stations. Physicochemical data indicated a well mixed upper 5 m of water column, below which discontinuities in temperature/salinity profiles indicated the influence of colder, more saline waters associated with deep offshore currents. Physicochemical variables were within the range for oligotrophic systems with a tendency towards mesotrophic in localized areas close to the shoreline. Signs of anthropogenic stress were associated with the eastern, southwestern and western sections of the bay. Of the over 120 species of phytoplankton found in the waters of Discovery Bay, most were neritic/oceanic and diatoms dominated while 11 were found to be potentially harmful species. While these harmful species occurred at all stations they occurred most frequently at stations on the eastern side of the bay. About 107 zooplankton species were identified, 52 of which were copepods. The species also represented a mix of neritic and oceanic taxa and mean abundances for the area ranged from 1077 m⁻³ at the mouth of the bay to 3794 m⁻³ close to the south shore (station 6). Generally stations closest to shore had greater zooplankton abundances than centrally located bay stations and stations close to oceanic influence. Acartia tonsa and Lucifer faxoni showed greatest densities at shoreline areas of the bay while Oithona plumifera, Undinula vulgaris and Temora stylifera were important at stations closest to oceanic influences. These species were thus considered as indicators of these different areas within the bay. From physicochemical data and the planktonic assemblage, Discovery Bay cannot be considered polluted, it is still more accurately classified as generally pristine with mesotrophic zones in the eastern and southeastern sections of the bay. These data therefore provide a real baseline of conditions for similar tropical coastal embayments.     

Comparison between the trypanorhynchid cestode infections of Penaeus duorarum and Penaeus brasiliensis in Biscayne Bay,Florida

Penaeus brasiliensis and P. duorarum from Biscayne Bay, Florida, were both found to be infected with four species of trypanorhynchid cestode larvae: Parachristianella monomegacantha, P. heteromegacanthus, Prochristianella penaei, and Renibulbus penaeus. The two shrimp species contained the cestodes in significantly different proportions and female P. duorarum had different proportions of cestodes than males. Three linear regressions of cestode infection on host size were also significant. The incidence and intensity of infection is given for each species of shrimp and cestode. This is the first record of P. heteromegacanthus and R. penaeus infecting Penaeus duorarum and modifies earlier information of P. duorarum infections in the bay.     

Ecology and distribution of diatoms in Biscayne Bay,Florida (USA): Implications for bioassessment and paleoenvironmental studies

The spatial and temporal distribution of planktonic, sediment-associated and epiphytic diatoms among 58 sites in Biscayne Bay, Florida was examined in order to identify diatom taxa indicative of different salinity and water quality conditions, geographic locations and habitat types. Assessments were made in contrasting wet and dry seasons in order to develop robust assessment models for salinity and water quality for this region. We found that diatom assemblages differed between nearshore and offshore locations, especially during the wet season when salinity and nutrient gradients were steepest. In the dry season, habitat structure was primary determinant of diatom assemblage composition. Among a suite of physicochemical variables, water depth and sediment total phosphorus (STP) were most strongly associated with diatom assemblage composition in the dry season, while salinity and water total phosphorus (TP) were more important in the wet season. We used indicator species analysis (ISA) to identify taxa that were most abundant and frequent at nearshore and offshore locations, in planktonic, epiphytic and benthic habitats and in contrasting salinity and water quality regimes. Because surface water concentrations of salts, total phosphorus, nitrogen (TN) and organic carbon (TOC) are partly controlled by water management in this region, diatom-based models were produced to infer these variables in modern and retrospective assessments of management-driven changes. Weighted averaging (WA) and weighted averaging partial least squares (WA-PLS) regressions produced reliable estimates of salinity, TP, TN and TOC from diatoms (r² = 0.92, 0.77, 0.77 and 0.71, respectively). Because of their sensitivity to salinity, nutrient and TOC concentrations diatom assemblages should be useful in developing protective nutrient criteria for estuaries and coastal waters of Florida.     

Temporal and spatial dynamics of macroalgal communities along an anthropogenic salinity gradient in Biscayne Bay (Florida,USA)

The seasonal and spatial dynamics of two groups of macroalgae, drift algae and rhizophytes, commonly found in tropical seagrass meadows were studied. The aim of this study was to provide insight into how freshwater discharges may be altering seagrass-dominated nearshore tropical habitats. Species composition, biomass, and percent cover of macroalgae were collected at six Thalassia testudinum König dominated sites within Biscayne Bay, Florida, representing three salinity regimes: canal-influenced, natural sheet-flow, and oceanic conditions. Mean annual salinities in these three regimes correspond to 10, 25 and 35 psu, respectively, with much greater variability in the canal and sheet-flow regimes, than in the oceanic condition. There were distinct changes in the composition of the macroalgal community along this salinity gradient. Drift algae (Chondria spp., Laurencia spp.) were most commonly found at canal-disturbed sites (10–85 g m⁻²), while rhizophytic calcareous green algae (Halimeda spp., Penicillus spp.) were most abundant at the higher salinity oceanic sites (20–105 g m⁻²). Seasonal patterns exhibited by the two groups differed also, with drift algae being more abundant in the cooler dry-season months, while rhizophytic algae were more abundant during the warmer wet-season months. These periods of higher abundance correlated with higher growth rates (drift = 2.3% day⁻¹, rhizophytes = 0.85% day⁻¹) measured in representative species for each group. Grazing rates on drift algae were found to be low for tropical habitats and did not differ much between canal (0.44% h⁻¹) and oceanic sites (0.42% h⁻¹).     

LIDAR optical rugosity of coral reefs in Biscayne National Park,Florida

The NASA Experimental Advanced Airborne Research Lidar (EAARL), a temporal waveform-resolving, airborne, green wavelength LIDAR (light detection and ranging), is designed to measure the submeter-scale topography of shallow reef substrates. Topographic variability is a prime component of habitat complexity, an ecological factor that both expresses and controls the abundance and distribution of many reef organisms. Following the acquisition of EAARL coverage over both mid-platform patch reefs and shelf-margin bank reefs within Biscayne National Park in August 2002, EAARL-based optical indices of topographic variability were evaluated at 15 patch reef and bank reef sites. Several sites were selected to match reefs previously evaluated in situ along underwater video and belt transects. The analysis used large populations of submarine topographic transects derived from the examination of closely spaced laser spot reflections along LIDAR raster scans. At all 15 sites, each LIDAR transect was evaluated separately to determine optical rugosity (Ro_tran), and the average elevation difference between adjacent points (Av(E_ap)). Further, the whole-site mean and maximum values of Ro_tran and Av(E_ap) for the entire population of transects at each analysis site, along with their standard deviations, were calculated. This study revealed that the greater habitat complexity of inshore patch reefs versus outer bank reefs results in relative differences in topographic complexity that can be discerned in the laser returns. Accordingly, LIDAR sensing of optical rugosity is proposed as a complementary new technique for the rapid assessment of shallow coral reefs.     

Seepage rate variability in Florida Bay driven by Atlantic tidal height

Atlantic tidal fluctuations drive pressure head variations in shallow offshore wells drilled into the limestone subsurface on both the Florida Bay and Atlantic sides of Key Largo, Florida, USA. We tested the hypothesis that these pressure head variations influence groundwater flow and that flux rate variability is associated with tidal variability. We used an automated Rn monitor to make continuous measurements of ²²²Rn, a natural tracer of groundwater discharge, in Florida Bay waters. We also deployed three types of seepage meters, including an automated heat pulse meter to collect a continuous record of seepage from the sediments. Drum type seepage meters inserted into soft sediments and fiberglass meters cemented to the rocky bay floor were utilized with pre-filled 4-l bag collectors, and monitored on an hourly basis. Maximum Rn inventories in Florida Bay waters were associated with high tide on the Atlantic side of the island. Modeling of the Rn variation indicated variable groundwater discharge rates with maximum flux occurring at high Atlantic tide. Seepage meter results in Florida Bay were consistent with ²²²Rn modeling. Florida Bay seepage meter rates showed positive correlation with Atlantic tide, meter 1, r?=?0.63, n?=?12, p?<?0.025 and meter 2, r?=?0.67, n?=?12, p?<?0.025. A seepage meter offshore of the Atlantic side of Key Largo exhibited rates that were inversely correlated with Atlantic tide (r?=?0.87, n?=?9, p?<?0.005) showing negative rates when the tide was high, and positive rates when the tide was low. Overall, our results are consistent with the hypothesis of Reich et al. (2002), that pressure head variations driven by Atlantic tide influence groundwater seepage rate variability in Florida Bay off Key Largo. Effectively, as proposed by Reich et al. (2002), Key Largo functions as a semi-permeable dam separating Florida Bay and the Atlantic Ocean.     

Nutrient concentrations in tidal creeks as indicators of the water quality role of mangrove wetlands in Southwest Florida

Coastal mangroves have the potential to improve the water quality of urban and rural runoff before it is discharged into adjacent coastal bays and oceans; but they also can be impaired by excessive pollutants from upstream. Nutrients (phosphorus and nitrogen), salinity, and other water quality parameters were measured in five mangrove tidal creeks in different hydrogeomorphic and urbanization settings during high and low tides over a calendar year of wet (June and August 2015) and dry (February and April 2016) seasons in the Greater Naples Bay area in Southwest Florida, USA. Nutrient concentrations (ave. ± std error) in the tidal creeks were 0.055 ± 0.008 mg-P/L for total phosphorus (TP) and 0.610 ± 0.020 mg-N/L for total nitrogen (TN), with an average N:P ratio of 11.4:1. Average wet season TP (0.075 ± 0.010 mg-P/L) was significantly higher than the dry season TP (0.033 ± 0.003 mg-P/L; p < 0.01, f = 15.17, f_crit = 3.89) and the average wet season TN (0.75 ± 0.03 mg-N/L) was significantly higher than dry season TN (0.52 ± 0.02 mg/L; p < 0.01, f = 64.14, f_crit = 3.89), suggesting that urban stormwater runoff is directly or indirectly affecting the nutrient conditions in these mangroves. Significant differences in nutrient concentrations between low tide and high tide were not found for either TP (p = 0.43, f = .63, f_crit = 3.88) or TN (p = 0.20, f = 1.66, f_crit = 3.89). These differences were confirmed by a PCA and cluster analyses, which found differences to be seasonal. We could not conclude from these results whether these five mangrove wetlands were sources nor sinks of nutrients based simply on the measurement of nutrient concentrations. But we illustrated that nutrient concentrations were indicators of the mangroves’ hydrogeomorphic settings, their tidal fluxes from Naples Bay, and the Bay's upstream watersheds, and less by direct urban runoff.     

Land use indicators in life cycle assessment

Purpose  

Inclusion of land use-related environmental aspects into LCA methodology has been under active development in recent years. Although many indicators have been developed and proposed for different aspects of land use (climate change, biodiversity, resource depletion and soil quality), many of indicators have, as yet, not been tested and compared in LCA applications. The aim of this study is to test the different LCIA indicators in practice in a case study of beer production.     

Relationships Between Reef Fish Communities and Remotely Sensed Rugosity Measurements in Biscayne National Park,Florida, USA

The realization that coral reef ecosystem management must occur across multiple spatial scales and habitat types has led scientists and resource managers to seek variables that are easily measured over large areas and correlate well with reef resources. Here we investigate the utility of new technology in airborne laser surveying (NASA Experimental Advanced Airborne Research Lidar (EAARL)) in assessing topographical complexity (rugosity) to predict reef fish community structure on shallow (<10 m deep) patch reefs. Marine portions of Biscayne National Park, Florida, USA, were surveyed remotely using the EAARL, and reef fish populations were visually surveyed on 10 patch reefs at independent, randomly selected stations (n = 10–13 per reef). Rugosity at each station was assessed in situ by divers using the traditional chain-transect method (10-m scale), and remotely using the EAARL submarine topography data at multiple spatial scales (2, 5, and 10 m). The rugosity and biological datasets were analyzed together to elucidate the predictive power of EAARL rugosity in describing the variance in reef fish community variables and to assess the correlation between chain-transect and EAARL rugosity. EAARL rugosity was not well correlated with chain-transect rugosity, or with species richness of fishes (although statistically significant, the amount of variance explained by the model was very low). Variance in reef fish community attributes was better explained in reef-by-reef variability than by physical variables. However, once the reef-by-reef variability was taken into account in a two-way analysis of variance, the importance of rugosity could be seen on individual reefs. Fish species richness and abundance were statistically higher at high rugosity stations compared to medium and low rugosity stations, as predicted by prior ecological research. The EAARL shows promise as an important mapping tool for reef resource managers as they strive to inventory and protect coral reef resources.     

Nitrate relationships between stream baseflow,well water,and land use in the Tomorrow-Waupaca Watershed

We examined the use of stream baseflow water quality as a representative measure of mean ground water quality in the Tomorrow-Waupaca Watershed in central Wisconsin and the relationship between agricultural land use and watershed water quality. From 1997 to 1999, 38 stream sites were sampled for nitrate during winter and summer baseflow conditions. Some sites have been sampled during winter baseflow conditions since 1994. The land area contributing ground water to each stream sampling site was delineated, resulting in 38 sub-basins. In addition, over 3500 test results from private wells in the watershed were compiled and mapped using a Geographic Information System (GIS). Nitrate concentrations in stream baseflow and well waters were found to have strong positive correlation in the sub-basins of second order or higher. This indicates that stream baseflow may be valid for monitoring mean ground water quality in watersheds predominantly fed by ground water, where much of the stream nitrate is believed to originate from ground water. Analysis of seasonal variation in the stream data showed that winter nitrate concentrations were higher than summer concentrations, implying that winter stream monitoring may be more critical for the assessment of overall ground water quality in the watershed. We also found that, as the amount of agricultural land increased in each sub-basin, average nitrate concentrations in the well and stream waters also increased, suggesting a connection between agricultural land use and nitrate contamination of water resources in the watershed.     

青弋江流域大型底栖动物群落结构及水质评价

研究河流大型底栖动物群落结构特征及水环境质量对水生态的保护与修复具有重要意义。以青弋江流域为研究对象,于2020年9月进行了大型底栖动物及水体理化因子的调查,采用相对重要性指数、生物多样性指数及Jaccard相似性系数分析了大型底栖动物群落结构特征,运用丰度/生物量比较曲线法及冗余分析法探究了底栖动物群落受到的干扰程度及其主要影响环境因子,最后利用水生态环境质量综合指数对河流水质进行评价。研究结果表明：(1)共采集鉴定大型底栖动物61种,隶属于3门6纲17目,平均丰度为265.9个/m~2,平均生物量41.6 g/m~2。相对重要性指数分析显示,日本沼虾(Macrobrachium nipponensis)、中国圆田螺(Cipangopaludina chinensis)、羽摇蚊(Chironomus plumosus)及扁蜉(Ecdyrus)为群落中的主要优势种。(2)由群落相似性分析知,Jaccard相似性系数较低,调查点位之间存在较强的空间异质性。(3)冗余分析表明,电导率、氨氮浓度及流速是影响底栖动物群落结构的主要环境因子。(4)生物指数分析结果显示该流域水质为轻度污染或中度污...     

Effects of land use and environmental factors on the variability of soil quality indicators in hilly Loess Plateau region of China

Classical statistics methods were adopted to analyze the soil quality variability, its affecting factors, and affecting degree at a regional scale (700 km2) in the central part of hilly Loess Plateau region of China. There existed great differences in the variability of test soil quality indicators. Soil pH, structural coefficient, silt content, specific gravity, bulk density, total porosity, capillary porosity, and catalase activity were the indicators with weak variability; soil nutrients (N, P, and K) contents, CaCO3 content, cation exchange capacity (CEC), clay content, micro-aggregate mean mass diameter, aggregate mean mass diameter, water-stable aggregates, respiration rate, microbial quotient, invertase and phosphatase activities, respiratory quotient, and microbial carbon and nitrogen showed medium variation; while soil labile organic carbon and phosphorus contents, erosion-resistance, permeability coefficient, and urease activity were the indicators with strong variability. The variability of soil CaCO3, total P and K, CEC, texture, and specific gravity, etc. was correlated with topography and other environmental factors, while the variability of dynamic soil quality indicators, including soil organic matter content, nitrogen content, water-stable aggregates, permeability, microbial biomass carbon and nitrogen, enzyme activities, and respiration rate, was mainly correlated with land use type. Overall, land use pattern explained 97% of the variability of soil quality indicators in the region. It was suggested that in the evaluation of soil quality in hilly Loess Plateau region, land use type and environmental factors should be fully considered.     

模拟水流扰动对香溪河库湾浮游病毒-宿主动态的影响

【背景】浮游病毒是淡水生态系统的重要组成部分,在调节浮游细菌和藻类群落结构及调控系统物质循环过程中起着重要的作用。水库具有不同于湖泊的水动力过程,产生的扰动可能影响浮游病毒的调控功能。【目的】研究水力扰动对浮游病毒-宿主动态的影响,为阐释水库生境下浮游病毒生态功能提供理论依据。【方法】以香溪河库湾原水为材料,模拟不同流速扰动对病毒-宿主动态的影响;通过病毒丰度、宿主丰度、宿主裂解率、宿主溶源诱导率等参数的变化反映这种动态变化过程,并分析其与环境因子间的关系。【结果】0.05 m/s和0.10 m/s的流速扰动强度对浮游植物和浮游细菌生长有显著促进作用,但扰动对浮游病毒丰度的影响不显著;扰动能促进病毒介导的浮游植物和细菌裂解率上升,而且0.05 m/s扰动强度的促进作用大于0.10 m/s;同时,扰动显著降低了浮游植物溶源诱导率,但引起浮游细菌溶源诱导率的显著上升(P<0.05)。【结论】模拟扰动对浮游病毒-宿主动态过程产生了显著的影响,表明水库浮游病毒维持种群延续的生态策略可能与湖泊浮游病毒存在差异。     

Diversity, disturbance, and sustainable use of Neotropical forests: insects as indicators for conservation monitoring

Sustainable use of tropical forest systems requires continuous monitoring of biological diversity and ecosystem functions. This can be efficiently done with early warning (short-cycle) indicator groups of non-economical insects, whose population levels and resources are readily measured. Twenty-one groups of insects are evaluated as focal indicator taxa for rapid assessment of changes in Neotropical forest systems. Composite environmental indices for heterogeneity, richness, and natural disturbance are correlated positively with butterfly diversity in 56 Neotropical sites studied over many years. Various components of alpha, beta and gamma-diversity show typical responses to increased disturbance and different land-use regimes. Diversity often increases with disturbance near or below natural levels, but some sensitive species and genes are eliminated at very low levels of interference. Agricultural and silvicultural mosaics with over 30% conversion, including selective logging of three or more large trees per hectare, show shifts in species composition with irreversible loss of many components of the butterfly community, indicating non-sustainable land and resource use and reduction of future options. Monitoring of several insect indicator groups by local residents in a species-rich Brazilian Amazon extractive reserve has helped suggest guidelines for cologically, economically, and socially sustainable zoning and use regimes.     

Land use and biodiversity indicators for life cycle impact assessment

Background  The primary purpose of environmental assessment is to protect biological systems. Data collected over the last several decades indicates that the greatest impacts on biological resources derive from physical changes in land use. However, to date there is no consensus on indicators of land use that could be applicable worldwide at all scales. This has hampered the assessment of land use in the context of LCA. Objectives  The Institute for Environmental Research and Education and its partner Defenders of Wildlife have begun an effort to develop the necessary consensus. Methods  In July 2000, they held a workshop attended by a diverse group of interested parties and experts to develop a preliminary list of life cycle indicators for land use impacts. Results  Their preliminary list of impact indicators includes: protection of priority habitats/species; soil characteristics: soil health; proximity to & protection of high priority vegetative communities; interface between water and terrestrial habitats/buffer zones; assimilative capacity of water and land; hydrological function; percent coverage of invasive species within protected areas; road density; percent native-dominated vegetation; restoration of native vegetation; adoption of Best Management Practices linked to biodiversity objectives; distribution (patchiness; evenness, etc.); and connectivity of native habitat. Conclusion  The list of indicators conforms well to other efforts in developing indicators. There appears to be convergence among experts in the field and in related fields on the appropriate things to measure. Future Prospects  These indicators are currently being tested in the United States. Further workshops and testing is planned towards developing internationally recognized indicators for land use.     

Macroinvertebrate assemblage patterns as indicators of water quality in the Xindian watershed,Taiwan

In the present study, we assessed the water quality along a stretch of the watershed with considerable economic importance at the Xindian in Taiwan, using macroinvertebrate assemblages, along with environmental variables. The research was carried out at the seven sampling sites (abbreviated as XD1–XD7) where human impacts varied in intensity from upstream tributaries to the downstream of the Xindian watershed from December 2010 to December 2011. All variables except for the hardness, pH, dissolved oxygen, conductivity, turbidity, phosphate, ammonia, and alkalinity were significantly different (P < 0.05) between the sampling sites. A total of seventy seven taxa belonging to forty five families within eight insect orders, along with three non-insect invertebrate taxa were recorded, with most representative orders being Ephemeroptera and Diptera. Mean values of the density, abundance of macroinvertebrates, Shannon index, Simpson index, and Pielou's evenness were much higher in the reference sites, XD2, XD3, and XD4 compared with impacted sites, XD5, XD6, and XD7. Most of the benthic metrics were greatest in the reference site compared to the impacted site. Only the composition measures, percentages of Chironomidae and Oligochaeta which are more tolerant to pollution were dominant in the impacted site, XD7. As the results of assessment by different benthic metrics, water quality of Xindian watershed became gradually worse from upstream to downstream. Generally, our results suggest that macroinvertebrate assemblages can be used for assessment of water quality.