Indicators Of Aquatic Health Research Articles

Diversity of freshwater algal assemblages across the United States as revealed by DNA metabarcoding

AbstractAs freshwater algae respond strongly to environmental conditions, algal communities are routinely used as indicators of aquatic health. Algal bioassessments have historically relied upon microscopy‐based identifications that are typically slow, expensive, taxonomically restricted, and inconsistent across analysts and time. Metabarcoding of water column DNA (environmental DNA, or eDNA) can characterize assemblages more quickly, at lower cost, and with higher taxonomic precision than microscopy. As such, eDNA metabarcoding has the potential to improve bioassessments, but relationships between environmental conditions and eDNA‐derived algal assemblage composition need to be determined first. We performed metabarcoding of a plastid 23S rRNA gene region for 1230 freshwater eDNA samples collected from 51 lakes and 617 streams across the conterminous United States to test for assemblage‐wide patterns that may indicate ecological condition. Samples were collected by citizen, academic, and research scientists using a standardized commercial kit. This effort constitutes the largest published water column eDNA survey yet of algal diversity across freshwaters in the United States. We detected 14,943 algal exact sequence variants (ESVs) from 11 divisions. The richness and abundance of cyanobacteria was higher in lakes, while streams were dominated by diatoms. Nationwide, only 1% of variation in stream assemblages was explained by catchment integrity. The remaining, explicable 19% was associated with forest cover, stream order, elevation, and broad‐scale spatial variables. Nevertheless, select ESVs were candidate indicators of gradients in stream catchment integrity and possible eutrophication. Together, we show that algal eDNA metabarcoding has potential for measuring ecological condition relative to water quality. Yet, further sampling along anthropogenic gradients is needed before algal eDNA can be used for large‐scale biomonitoring in the United States. We also found that only 2% of algal ESVs could be assigned to U.S. morphospecies, highlighting the importance of building a more comprehensive reference sequence database to integrate existing morphospecies autecology with eDNA‐based bioassessments.

A Numerical Tool for Dissolved Oxygen Simulation in the Western Mississippi Sound

Bazgirkhoob, H.; Linhoss, A., and Armandei, M., 2022. A numerical tool for dissolved oxygen simulation in the western Mississippi Sound. Journal of Coastal Research, 38(4), 699–711. Coconut Creek (Florida), ISSN 0749-0208. Dissolved oxygen is an indicator of aquatic health. Hydrodynamic–water quality models facilitate the understanding of flow dynamics and dissolved oxygen in estuarine systems. In this study, dissolved oxygen concentration, seasonality, and vertical stratification were studied in the western Mississippi Sound, Northern Gulf of Mexico. Visual Environmental Fluid Dynamic Code and the water quality model CE-QUAL-ICM were linked together to develop a three-dimensional hydrodynamic and water quality model of the western Mississippi Sound. The model was verified and validated for nutrients and chlorophyl a. Then, the modeled results for dissolved oxygen were compared to measured data. Mean observed dissolved oxygen ranged between 6.29 and 8.48 mg/L in the top and bottom layers at each site. The root mean squared error between measured and modeled dissolved oxygen ranged between 1.30 and 2.87 mg/L. Results indicate that the model was able to capture measured seasonal trends and vertical stratification. The model simulated more realistic results in shallower areas compared to deeper areas. Overall, the model simulated slightly higher dissolved oxygen than what was measured, although 27% of the stations showed no statistical difference between the modeled and measured dissolved oxygen. These results are useful for interpreting the value of this model for future ecological studies. The model can be used as a tool to provide better understanding of the dissolved oxygen dynamics due to multiple scenarios such as hurricanes and storms.

Toward in situ zooplankton detection with a densely connected YOLOV3 model

Zooplankton play an important role in the global marine carbon cycle, and as a useful indicator of aquatic health, the distribution and abundance of zooplankton organisms could provide early warning for natural disasters. With the rapid development of the observation sensors and platforms, many advanced detection methods such as deep neural networks are pursued to realize the in situ and autonomous zooplankton observation. However, the features of zooplankton might be lost in the deep neural network transmission due to both convolution and down-sampling operations, especially for the subtle features which are critical in the identification of the zooplankton taxonomic group. Therefore, this paper proposed an improved YOLOV3 model with densely connected structures to improve the reusability of the features during transmission in the model. The experiment results demonstrate the performance of the proposed method is more suitable for the in situ zooplankton detection by comparing it with other state-of-the-art models.

A brief overview of the application of pollution monitoring indices on Amrit Ganga river, Uttarakhand, India

Benthic macroinvertebrates are an indispensable part of aquatic ecosystems. They are used repetitively for evaluation of aquatic health since the emergence of the industrial revolution. Several studies show that their presence and absence are an indicators of aquatic health. In our study at the Amrit Ganga river, four sampling stations (consisting of sampling points each) were selected for the collection of aquatic macroinvertebrates. A total of n= 465 individuals were collected during the sampling period in which Trichoptera and Diptera appeared as dominant orders. According to functional feeding groups, the presence of filters and scrapers was higher than that of detritivore, and the presence of predators was lowest. Based on the presence of sensitive orders,%EPT (Ephemeroptera, Plecoptera, and Trichoptera) was calculated, and the maximum value calculated was 74.5% in (site 2) and the minimum value was 21% in (site 4). We also quantified the Water Quality Index approach which is based on physicochemical properties of water and the minimum and maximum values of WQI (Water Quality Index) varies from 33.94 in Site 2 to 48.61 in Site 4, indicating

Bacterioplankton Dynamics within a Large Anthropogenically Impacted Urban Estuary.

The abundant and diverse microorganisms that inhabit aquatic systems are both determinants and indicators of aquatic health, providing essential ecosystem services such as nutrient cycling but also causing harmful blooms and disease in impacted habitats. Estuaries are among the most urbanized coastal ecosystems and as a consequence experience substantial environmental pressures, providing ideal systems to study the influence of anthropogenic inputs on microbial ecology. Here we use the highly urbanized Sydney Harbor, Australia, as a model system to investigate shifts in microbial community composition and function along natural and anthopogenic physicochemical gradients, driven by stormwater inflows, tidal flushing and the input of contaminants and both naturally and anthropogenically derived nutrients. Using a combination of amplicon sequencing of the 16S rRNA gene and shotgun metagenomics, we observed strong patterns in microbial biogeography across the estuary during two periods: one of high and another of low rainfall. These patterns were driven by shifts in nutrient concentration and dissolved oxygen leading to a partitioning of microbial community composition in different areas of the harbor with different nutrient regimes. Patterns in bacterial composition were related to shifts in the abundance of Rhodobacteraceae, Flavobacteriaceae, Microbacteriaceae, Halomonadaceae, Acidomicrobiales, and Synechococcus, coupled to an enrichment of total microbial metabolic pathways including phosphorus and nitrogen metabolism, sulfate reduction, virulence, and the degradation of hydrocarbons. Additionally, community beta-diversity was partitioned between the two sampling periods. This potentially reflected the influence of shifting allochtonous nutrient inputs on microbial communities and highlighted the temporally dynamic nature of the system. Combined, our results provide insights into the simultaneous influence of natural and anthropogenic drivers on the structure and function of microbial communities within a highly urbanized aquatic ecosystem.

Evaluation of WET Testing as an Indicator of Aquatic Health

This project evaluated the quality of data needed to determine relationships between chronic Whole Effluent Toxicity (WET) test results and instream biological condition. A data quality objectives approach was used, which included several proposed measurement quality objectives (MQOs) that specified desired precision, bias, and sensitivity of methods used. Six facilities (four eastern and two western U.S.) participated in this study, all having design effluent concentrations > 60% of the stream flow. In accordance with a Quality Assurance Project Plan most of the facilities completed four quarters of chronic Ceriodaphnia dubia, and Pimephales promelas (fathead minnow) WET tests, and three quarters of Selenastrum capricornutum (green algae) WET testing following the most recent USEPA methods. Several other WET tests were conducted to address MQOs including splits, duplicates, and blind positive and negative controls. Macroinvertebrate, fish, and periphyton bioassessments were conducted at multiple locations up and downstream of each facility following the most recent USEPA Office of Water bioassessment protocols. Test acceptance criteria were met for most WET tests, however, this study demonstrated the need to incorporate other MQOs in a full study (such as minimum and maximum percent significant differences and performance on blind samples) to ensure accurate interpretation of effluent toxicity. More false positives, lower test endpoint (i.e., higher toxicity), and more “failed” (non-compliant) tests were observed using No Observed Effect Concentrations (NOEC) as compared to IC25s (concentration causing = 25% decrease in organism response compared to controls). Algae tests often yielded the most effluent toxicity in this study, however, this test was most susceptible to false positives and high inter-laboratory variability. WET test results exhibited few relationships with bioassessment results, even when incorporating actual effluent dilution. Neither frequency of WET non-compliance nor magnitude of WET were clearly related to differences in biological condition up and downstream of a discharge for the most part. Macroinvertebrate assessments were most able to discriminate small changes downstream of the effluent, followed by periphyton and then fish. The sampling methods used were robust but a full study should collect more field replicates up and downstream of each discharge to increase detection power. Macroinvertebrate and periphyton assessments together appeared to be sufficient to address project objectives. Fish assessments could be useful as well but would entail more effort and cost per site than expended in this project to be useful. This title belongs to WERF Research Report Series ISBN: 9781843397687 (Print) ISBN: 9781780403793 (eBook)