Use Of Biological Indicators Research Articles

Perceptions and knowledge about the use of biological indicators in freshwater ecosystem monitoring in Rwanda

The use of biological monitoring (biomonitoring) to assess water quality is recognised alongside the use of chemical and physicochemical parameters due to its ability and efficiency in providing information about both current and long-term changes. Indeed, biomonitoring is applied in several developed and developing countries. Nevertheless, some developing countries, such as Rwanda, are yet to adopt such a monitoring system. This paper presents results of an assessment of the knowledge and perceptions by water resource managers about the use of biomonitoring and bioindicators, and challenges to their integration into existing routine water quality monitoring systems in Rwanda. Qualitative research, using semistructured interviews, was conducted with nine water resource practitioners from six water governance institutions between August and November 2021. The results show that participants are aware that macroinvertebrates, algae and fish are bioindicators that have potential applications in Rwanda to complement the chemical and physicochemical parameters already being collected in the country’s water monitoring system. The main challenges for integration of biological indicators, as indicated by participants, include the need for equipment, funding, technical skills and taxonomic knowledge. Training in the use of bioindicators and taxonomy are needed to raise the awareness and skills of staff from the institutions involved in freshwater ecosystem management in Rwanda, and to encourage integration of biomonitoring results into national water monitoring frameworks.

Comparative Study of Water Quality Across Different Seasons in the Gregório River Watershed, São Paulo, Brazil

The goal of this study was to monitor the water quality in the Gregório river, São Carlos, São Paulo during the dry and rainy seasons using traditional methods such as physical and chemical analysis of the water and biological indicators. Six sampling points were monitored, ranging from the nearest location to the source of the river to its confluence with the Monjolinho river. Physical and chemical parameters of water (water surface temperature, dissolved oxygen, pH, and conductivity) were measured using a multiparameter probe. The distance between the points was determined according to the access to the site: from P1 to P2 (1328 m), from P2 to P3 (1278 m), from P3 to P4 (201 m), from P4 to P5 (820 m), and finally from P5 to P6 (1814 m). The biotic index used in conjunction with the environmental variables was the Biological Monitoring Working Party (BMWP), a qualitative index that utilizes benthic macroinvertebrates to classify water quality. Ceratopogonidae, Chironomidae, Chironomus, Enchytraeidae, Hirudinea, and Naididae were recorded at sites P1, P2, and P6 during both the dry and rainy seasons. This study, particularly at P6, it was observed that despite the higher concentration of dissolved oxygen compared to the other analyzed sites, which would indicate good water quality, the BMWP indicated that the location had a strongly polluted water quality, suggesting that environmental factors must be associated with biological indicators. It was concluded that the use of biological indicators along with environmental data provided a more reliable understanding of water quality.

Benthic macroinvertebrates as bioindicators to detect the level of water pollution in the upstream segment of Brantas River Watershed in Malang, East Java, Indonesia

Abstract. Hertika AMS, Sudaryanti S, Musa M, Amron K, Putra RBDS, Alfarisi MA, Hidayat MR, Pertiwi M, Halimah MF. 2024. Benthic macroinvertebrates as bioindicators to detect the level of water pollution in the upstream segment of Brantas River Watershed in Malang, East Java, Indonesia. Biodiversitas 25: 632-643. The Brantas River is the second longest river on the island of Java after the Bengawan Solo River. The current condition of the Brantas River is facing a worrying decline in water quality due to community activities in the surrounding area. This decline can have a negative impact on both aquatic biota and community welfare. To assess water quality, one method involves the use of biological indicators, specifically benthic macroinvertebrates. The objective of this research is to assess the water quality upstream of the Brantas River by using benthic macroinvertebrate as bioindicators. The assessment is based on the community structure, Biological Monitoring Working Party-Average Score Per Taxon (BMWP-ASPT) method and physico-chemical water parameters. This research was conducted at 10 sampling stations with 5 stations located in Batu City and 5 stations located in Malang City. The benthic macroinvertebrate result consists of 8 classes, 53 families. namely Bivalves (2 families), Clitellata (2 families), Gastropoda (5 families), Hirudinea (1 family), Insecta (35 families), Malacostraca (4 families), Oligochaeta (2 families), Polychaeta (1 family), and Turbellaria (1 family). The abundance of macroinvertebrates ranged from 181-2879 individuals/m2, while the diversity index ranged from 0.563-2.988. The evenness index ranged from 0.208-0.870, while the Simpson dominance index ranged from 0.061-0.799. The ASPT range of the upstream segment of Brantas River was found to be between 2.80-6.19, indicating a variation in water conditions from poor to excellent. The physico-chemical water as supporting parameters is still optimal, except for ammonia, total organic matter, and total dissolved parameters that exceed the quality standard. The results of this research show that based on benthic macroinvertebrates as bioindicators, the BMWP-ASPT index and water quality parameters as support, upstream to downstream the Brantas River watershed in Malang City has poor to very good quality. This is due to anthropogenic activities in land use which can disrupt the quality of aquatic ecosystems. Therefore, local governments need to manage waterfall ecosystems well by controlling human activities around them.

Enzymatic Indicators in Vaporized Hydrogen Peroxide Decontamination Cycles: Application-related Research focusing on Fractional Kill Time (FKT) and Reverse Fractional Kill Time (RFKT) Studies

The accepted standard from a regulatory perspective for vaporized hydrogen peroxide (vH2O2) cycle validation is the use of biological indicators (BIs). Novel enzymatic indicators (EIs) are gaining more importance in this field, relying on specific enzymatic reactions for their functionality. The aim of this work is to determine how enzymatic indicators can contribute to the cycle development process. Emphasis was placed on the initial informative study, the fractional kill time study, which is a basis for future studies. The results indicate that enzymatic indicators have the potential to facilitate further development of the cycle. This requires an analysis of the determined data, measured in relative light units (RLU), and aligning it with the BI growth, resulting in Full Kill/ No Kill limits. The use of enzymatic indicators for decontamination cycle development opens new perspectives and holds considerable potential for practical use in the development and validation of decontamination processes.

The influence of spatial processes on fish community structure: using a metacommunity framework for freshwater bioassessment.

The use of biological indicators in a bioassessment approach is important for inferences of anthropogenic stress in routine monitoring programs. One of the primary assumptions of bioassessment is that biological indicators observed at specific sampling sites will allow for inferences of local environmental quality; however, this assumption requires a reliable understanding of dispersal processes, which is particularly relevant in river systems due to their dendritic network. Inter-stream dispersal between different points of the river network could bias bioassessment, especially for highly mobile organisms like fish. Here, we examine standard biological metrics used in routine biomonitoring to determine how spatial variables, including dispersal, influence inferences between fish populations and environmental gradients. Using redundancy analysis (RDA) and variation partitioning, we tested the relative influence of both environmental and spatial variables on fish community structure and related community metrics. Fish were collected from 99 sampling sites distributed across 44 rivers and streams of the Great Morava River Basin, Serbia. Electroconductivity, the percentage of agricultural areas, dissolved oxygen, ammonia, and nitrate-nitrogen were found to be significant environmental variables, while ten spatial predictors from broad- to small-scales were found to influence fish community structure and community metrics. Our results suggest that contemporary dispersal among streams influences fish community composition, but that trait-based metrics are less sensitive than basic measures of diversity to spatial processes. Our results highlight the need for spatially independent sampling, as well as the need to consider dispersal-based processes in routine biomonitoring.

Sandy beach bioindicators: How each benthic taxon tells its own story

The use of biological indicators is one of the main strategies for monitoring anthropogenic impacts on sandy beaches. However, most studies performed so far have focused only on a few groups, mostly supralittoral and intertidal taxa, and did not consider how the environmental variability influences the performance of bioindicators, nor if these organisms can act as proxies of biodiversity or assemblage-level responses. The goal of this study was to evaluate the performance of several popular and under-evaluated sandy beach bioindicators from distinct groups to act as indicators of urbanization impacts, but controlling for and disentangling the effects of natural variability. We sampled a large set of sandy beach sites (n = 90) with distinct morphodynamic conditions and urbanization degrees to encompass a wide variability of natural and anthropogenic conditions. Almost all taxa affected by urbanization were also affected by morphodynamics. Natural variability explained a higher variance than urbanization in most cases, including for species such as the ghost crab O. quadrata and the polychaete Scolelepis spp. Although rarely included in environmental impact assessments, species inhabiting the sandy beach lower zones, such as polychaetes, showed good prospective as bioindicators. The potential of species to act as biodiversity surrogates was limited, and only the polychaete Scoloplos treadwelli was associated with a higher local diversity, an important measure of ecosystem ecological integrity. Overall, our results show that the use of bioindicators may provide a good cost-benefit approach in beach monitoring; however, management should consider beach morphodynamic type as individual units when choosing the adequate bioindicator. When the scale of management comprises multiple beaches with distinct morphodynamic characteristics, different bioindicators should be used to untangle the effects of beach type and anthropogenic activities. To expand the array of suitable bioindicators, our results indicate that sublittoral taxa should be better evaluated. The potential of benthic bioindicators to act as biodiversity surrogates was limited, and alternatives, such as biotic indices, may be more appropriate to uncover effects at the assemblage-level.

Histopathological changes in Lithobates catesbeianus tadpoles used as biomarkers of pesticide poisoning

The use of biological indicators has increased in recent years with the aim of investigating environmental pollution in aquatic environments that are vulnerable to the constant use of pesticides. Some biomarkers can help assess the health status, indicating physical, metabolic, and behavioral changes under acute and sublethal poisoning. The mixture of the active ingredients cyproconazole and picoxystrobin is a widely used fungicide for the control of pests in cotton, rice, coffee, sugarcane, corn, soybean, and wheat. The objective of this study was to verify the occurrence of possible histopathological lesions in the liver and kidneys of bullfrog tadpoles (Lithobates catesbeianus) caused by a fungicide commercial formula composed of picoxystrobin and cyproconazole. The animals were subjected to different concentrations of the fungicide to determine the median lethal concentration (LC50-96h = 0.05 mg L-1), that is, the lethal dose for 50% of the animals in 96 h. After determining the value of LC50-96h, the animals were subjected to three sublethal concentrations (LC50-96h/2, LC50-96h/10, and LC50-96h/100). Through histological biomarkers, it was verified that this fungicide changed the morphology of the animals' kidney and liver tissues in a chronic way, impairing the functioning of organs that are essential for their survival and metamorphosis, which can result in an imbalance in the biodiversity of aquatic ecosystems.

Application of Planarian Brain Regeneration: Detection of Water Pollution

Due to over industrialisation, the environmental pollution problem is becoming increasingly serious, especially in aquatic ecosystems. Compared with traditional physical and chemical detection methods, the use of biological indicators has become popular. The freshwater planarian Dugesia japonica is distributed extensively in aquatic ecosystems and has been applied to the area of environmental toxicology for its high chemical sensitivity. Moreover, D. japonica also has a powerful regenerative capability in which the injured planarian can regenerate a new brain in 5 days and complete an adult individual remodelling in 14 days. Therefore, it has been used as a new model organism in the field of neuro-regeneration toxicology. In our past study, D. japonica can be used as a biological indicator to detect water pollution. This can provide basic data for the detection of water pollution and provide a warning system in regard to aquatic ecosystems.

A paleolimnological context of ecological vulnerability for the freshwater ecosystems of Sable Island National Park Reserve, Canada.

Protected areas require long-term monitoring to understand the influence and extent of ecosystem stress to inform management and conservation decisions. As long-term data are not always available, paleolimnological methods offer a way of extending our knowledge of past environmental conditions necessary to use as context for remediation. Here, we examine four sediment cores and additional surface sediments from 14 ponds located on Sable Island National Park Reserve Canada (SINPR), where long-term ecological changes and vulnerability to disturbance are not well defined. We develop a paleolimnological approach to assessing environmental vulnerability through the use of biological indicators (Diptera: Chironomidae), where shifts in the environment are inferred by shifts in chironomid assemblages over time. Analysis of surface sediments show four distinct assemblage types reflecting four different habitat conditions; primarily represented by the presence of Glyptotendipes, Chironomus, Microtendipes, and Dicrotendipes. Differences in habitat conditions through time based on these results are then compared to biostratigraphic analysis of sediment cores from four of the ponds. We found that two ponds had large shifts in chironomids assemblages that were associated with changes in habitat over time, while two others that were not as exposed to the influence of erosion and influx of sand dunes did not. Our findings established a baseline of historical change in SINPR, broadening the scope of long-term monitoring, which is essential for defining goals for management and conservation of the ecological integrity of Sable Island.

Reproductive Biology of Female Pacific Halibut (Hippoglossus stenolepis) in the Gulf of Alaska

Developing a robust understanding of Pacific halibut reproductive biology is essential to understanding the different components (e.g. maturity) that determine the reproductive output of the species and, therefore, for estimating the relative female spawning biomass. With these, effective and proactive management strategies can be designed and implemented to face the large-scale environmental changes to which high-latitude spawning fish are particularly vulnerable. To date, reproductive studies of Pacific halibut have mainly focused on population or regional scales, leaving the specific details of organism-level reproductive development unexamined. The work described here aimed to address information gaps in Pacific halibut reproductive biology by conducting a detailed histological examination of temporal changes in ovarian development over an annual reproductive cycle with special attention to the use of biological indicators (e.g. oocyte diameter, gonadosomatic index, hepatosomatic index, Fulton’s condition factor, somatic fat) in characterizing female developmental stages and reproductive phases. Our results provide a foundation for future studies directed at improving current maturity estimations by histological assessment and explore models that test the utility of biological indicators to predict maturity in this important fish species.

Suitability of molecular taxonomy for assessing polluted sediments using the NemaSPEAR[%] index

Assessing the ecological consequences of marine and freshwater contamination is an important use of biological indicators. The NemaSPEAR[%] index is a nematode-based index for the evaluation of sediment quality and an expedient complement to macroinvertebrate-based indicator systems, especially for fine, cohesive sediments. While the NemaSPEAR[%] index in its original form is morphologically based, in this study the nematode communities of 38 locations with known sediment contamination were analyzed by light microscopy and metabarcoding to demonstrate the validity of a molecular-taxonomy-based NemaSPEAR[%] index. The results showed that the molecular-based index can reliably distinguish between sites of good, moderate, and bad pollution status. Moreover, a greater congruence with molecular read abundances were obtained after the morphology-based NemaSPEAR[%] index was corrected for differences in the biomass of different nematode species. However, incomplete reference databases hamper a full congruence between the species inventories recorded in morphological and molecular datasets. Another source of variability is the substantial difference in the biomass (and thus also of gene copies) of different species, thus evidencing a bias in abundance-based calculations of the NemaSPEAR[%] index. Despite these limitations, the molecular approach provides an expertise-free means of reliable bioindication using one of the most abundant and diverse components of benthic macroinvertebrate communities. Moreover, due to the ubiquity of nematodes, application of the index can be extended to wastewater, biofilm, and other lotic and lentic waters that require regular monitoring.

Achieving Success by Validation! Decontamination Protocols of Category A Medical Waste for Patients with Serious Communicable Diseases

<h3>Purpose</h3> During the 2014 Ebola outbreak, treatment centers for Ebola and special pathogens had to determine safe handling protocols for the management of category A infectious substances. There have been challenges achieving validation of adequate sterilization with autoclaving. To achieve successful inactivation requires alteration of cycle parameters (temperature, pressure, and time), and packaging methods. Successful inactivation is verified through the use of biological indicators, data loggers, and the evaluation of drain and exhaust lines. We aim to describe a successful waste sterilization process utilizing an autoclave in Emory University Hospital's biocontainment unit where we maintained appropriate safe handling waste processes. <h3>Methods & Materials</h3> Waste was differentiated by type to include patient general waste, linens, liquids, and sharps (including continuous renal replacement therapy cartridges). This helped us to determine appropriate packing methods and cycle parameters to ensure adequate inactivation by autoclaves. A biological indicator (BI) was used to monitor the efficacy of the autoclave sterilization process. Waste was double bagged with autoclave bags using the "gooseneck" method and secured with autoclave tape. This allowed for waste packaging to maintain closure of biohazard bags and contain leaks and aerosols. Following failed loads, action plans were generated until achieving successful inactivation. In order to determine the effectiveness of autoclave sterilization parameters, repeat loads were performed to ensure reliability. Once cycle specifications were finalized, each cycle type was repeated to achieve three successful runs with all passing biological indicators. <h3>Results</h3> We achieved effective inactivation of waste by altering autoclave factory settings. Following separation of waste and determine appropriate packing methods, we ran 26 total cycles achieving passing biological loads in 17 cycles. Failed loads occurred primarily in liquids and sharps where parameters were readjusted until achieving three successful cycles. <h3>Conclusion</h3> Safe handling of category A infectious waste requires validation of inactivation of waste by autoclave. Validation of autoclave parameters need to be assessed with particular attention to waste loads and packaging prior to treatment. We achieved successful inactivation of infectious medical waste with simulated patient waste loads while maintaining the integrity of waste packaging to ensure no leakage of liquid or aerosol particles occurred.

The Application of Active Biomonitoring with the Use of Mosses to Identify Polycyclic Aromatic Hydrocarbons in an Atmospheric Aerosol.

The use of biological indicators of environmental quality is an alternative method of monitoring ecosystem pollution. Various groups of contaminants, including organic ones, can be measured in environmental samples. Polycyclic aromatic hydrocarbons (PAHs) have not yet been determined by the moss bag technique. This technique uses several moss species simultaneously in urban areas to select the best biomonitoring of these compounds, which are dangerous to humans and the environment. In this research, a gas chromatography coupled with mass spectrometry was used for the determination of selected PAHs in three species of mosses: Pleurozium schreberi, Sphagnum fallax and Dicranum polysetum (active biomonitoring) and for comparison using an air filter reference method for atmospheric aerosol monitoring. The chlorophyll fluorescence of photosystem II (PSII) was also measured to assess changes in moss viability during the study. As a result of the study, the selective accumulation of selected PAHs by mosses was found, with Pleurozium schreberi being the best bioindicator—9 out of 13 PAHs compounds were determined in this species. The photosynthetic yield of photosystem (II) decreased by 81% during the exposure time. The relationship between PAHs concentrations in mosses and the total suspended particles (TSP) on the filter indicated the possibility of using this bioindicator to trace PAHs in urban areas and to apply the moss bag technique as a method supporting classical instrumental air monitoring.

Biological indicators: the gold standard to verify the sterilization steam in dentistry

Infection control in dental practice is a daily necessity, the correct way to ensure safe environments is to disinfect medical equipment and sterilize materials and instruments. There are common failures in sterilization cycles in dental offices, caused by various factors, mainly a mechanical failure, and human error. Biological indicators are prepared from thermo-resistant bacterial spores, used to determine the quality of the sterilization processes. There are different types of indicators on the market, however, it is necessary to promote and publicize the use of biological indicators as means of verification of the sterilization process, since their use is not frequent as indicated in the NOM-013-SSA2-2015, which must be every two months.

Communities of aquatic organisms in the system of ecological monitoring of streams at the Vostochny Cosmodrome (Russia)

The current data on the ecological state of streams at the launch site of the Vostochny Cosmodrome with the use of biological indicators are presented. Recommendations on the surface water biomonitoring of the cosmodrome and the booster rocket drop zones are given. It is shown that the system of biological monitoring of the cosmodrome, as a part of the Roscosmos environmental monitoring, should be coordinated with the Roshydromet monitoring.

Application of Enzyme Indicators in Hydrogen Peroxide Biodecontamination Cycle Development: A Critical Evaluation of Indicator Variability and Correlation to Biological Indicator Results.

An important prerequisite for aseptic production of pharmaceuticals is the appropriate reduction of microbiological contamination. Hydrogen peroxide is commonly applied as decontamination agent for such processes in barrier systems. The development and validation of the barrier decontamination cycles is usually performed with the use of biological indicators (Geobacillus stearothermophilus). However, these indicators inherit certain drawbacks. A new type of indicators became available lately, based on the use of enzyme as a substance decomposed by hydrogen peroxide. There is no broad experience on the practical application of these enzyme indicators yet. Therefore, we investigated the practical use of enzyme indicators in comparison with biological indicators. To broaden the understanding on how these indicators might be used in practice, we provided an evaluation of indicator response variability and the correlation of enzyme indicator results to biological indicator results. In this study, we found the variability of the quantitative enzyme indicator reading to be < 30%, which is much smaller than the variability for spore enumeration of biological indicators (-50% to +300%). Further, we introduced a universal normalization approach to enable convenient comparison and evaluation of different enzyme indicator results. Finally, we discussed a new approach to establish a quantitative correlation between enzyme indicators and biological indicators with the use of threshold values to extrapolate theoretical biological indicator group results. We take the findings of this study as a basis for a suggestion on the practical application of enzyme indicators. We expect that the discussed possibilities of correlating enzyme indicator results to biological indicator results will allow the combined practical use of both indicator types. This would enable the continued application of proven approaches in new ways. Beyond this, the fast reading of enzyme indicators with the gain of significant quantitative information might result in faster and safer qualification and validation of pharmaceutical production equipment in the future.

Eficacia de esterilización del instrumental odontológico en las centrales de esterilización de la Facultad de Odontología de la Universidad Central del Ecuador, mediante la utilización de indicador biológico

El riesgo por infección cruzada se encuentra permanentemente durante la práctica odontológica, razón por la cual es vital aplicar las normas de bioseguridad y mantener un control estricto del proceso de esterilización del material e instrumental empleado; para esto, la utilización de indicadores biológicos ayuda a obtener mayor confiabilidad en la determinación de la eficacia del proceso esterilización, ya que evidencian la destrucción o no de esporas. Objetivo: Establecer la eficacia de esterilización por calor húmedo del instrumental odontológico en las centrales de esterilización de pregrado, quirófano y exodoncia de la FOUCE, mediante el uso de indicador biológico en la capacidad máxima de las autoclaves. Materiales y métodos: la investigación fue desarrollada en el autoclave de las centrales de esterilización de pregrado, quirófano y exodoncia FOUCE, colocando un indicador biológico en cada uno de ellos a 121ºC, 1 atmósfera y activando el proceso de esterilización propiamente dicha por 20 minutos, para luego de ser incubado obtener el resultado. Este estudio se llevó a cabo en dos ciclos de esterilización al día, dos días a la semana, durante un mes. Resultados: En la central de esterilización de pregrado, el 100% de sus muestras fueron negativas a presencia de esporas. En la central de esterilización de quirófano el 50% de las muestras fueron negativas y el 50% positivas. Y en la central de esterilización de exodoncia el 94% de las muestras fueron negativas y el 6,0% positivas. Conclusión: La Facultad de odontología de la Universidad Central del Ecuador, en sus centrales de esterilización de pregrado, exodoncia y quirófano cuentan con una eficacia del 81,25%.

Forest cover influences zooplanktonic communities in Amazonian streams

Deforestation of riparian areas is a major driver of biodiversity loss in aquatic ecosystems. Thus, we investigated the influence of forest cover and physical and chemical characteristics of streams on zooplankton communities in the southeastern Amazon. We addressed the following questions: (1) Are environmental factors (water physical and chemical characteristics and landscape variables) and dispersive processes (reflected in the spatial structure among sampling sites) efficient predictors of zooplankton communities in different hydrologic seasons? (2) Can zooplankton species be indicators of watersheds’ forest-cover levels? We sampled 15 streams located in nine rural settlements in northern Mato Grosso, Brazil, in the dry (August) and rainy (March) seasons of 2017. The forest-cover level had a significant effect on the physical and chemical characteristics (conductivity, dissolved oxygen, and temperature) of streams and also on the structure and composition of zooplankton communities, mainly of rotifers and testate amoebae. Areas with low vegetation cover had seasonal changes in species richness, individuals density, and zooplankton community structure. Environmental and spatial variables had no significant effect on the structure of zooplankton communities, which may indicate the strong influence of stochastic factors. Species from three zooplankton groups (rotifers, microcrustaceans, and testate amoebae) were indicators of forest-cover classes. This study provided valuable contributions to the conservation of riparian ecosystems and the use of biological indicators in environmental monitoring programs.

LA APLICACIÓN DE LODOS RESIDUALES AFECTA, A CORTO PLAZO, BIOMASA MICROBIANA Y SU ACTIVIDAD EN SUELOS SÓDICOS

The effect of applying sewage sludge to sodic soil on C and N mineralization, microbial biomass, microbial enzymatic activity and biological indicators were evaluated. The sodic soil was agricultural, and the incubation experiment was performed at the laboratory level at 56 days with three treatments: control sodic soil group (T1), sodic soil + sewage sludge at 20 Mg/ha (T2) and at 40 Mg/ha (T3). The results obtained for T2 and T3 were: 56.89 and 33.81 % mineralized C, 3.04 and 1.66 % mineralized N, 0.81 and 0.50 % immobilized carbon by microbial biomass in relation to control (T1). The microbial enzymatic activity increased 2.81 and 3.59 times for T2 and T3 with respect to T1. In the biological indicators qCO2, qFDA and Nmin/Cmic, an increase was observed at the beginning of the mineralization dynamics and gradually decreased over time. The application of sewage sludge to sodic soil had a positive effect on the mineralization of C and N, as well as microbial biomass in the short term. The T2 treatment presented a greater efficiency in the mineralization and immobilization of C, but with respect to N mineralization and microbial enzymatic activity no significant differences were found between T2 and T3. It is recommended to evaluate the application doses of the sewage sludge before its application to sodic soils. It is the first time that the use of biological indicators has been reported to evaluate the application of sewage sludge in a sodic soil of Mexico.

Herbaceous Understory Indicators of Post-Harvest Recovery in Coast Redwood (&amp;lt;i&amp;gt;Sequoia sempervirens&amp;lt;/i&amp;gt;) Forests

Assessment of forest recovery following disturbance is enhanced by the use of biological indicators. One such indicator, the abundance of understory species, was examined in coast redwood (Sequoia sempervirens) forests using non-metric multiple dimensional scaling (NMDS) and indicator species analysis (ISA). Randomly distributed 10 m diameter circular plots were employed to record the abundance of all understory species across three treatments: actively managed (0 - 45 years since harvest); mature second-growth (~80 - 120 years since harvest); and unharvested old-growth stands. NMDS with perMANOVA analysis signified separation between treatments with the shade tolerant herbaceous species Trillium ovatum, Viola sempervirens, and Oxalis oregana positively correlated with mature second-growth and old-growth treatments. ISA supported the inclusion of T. ovatum, with the addition of Prosartes hookerii, as indicators of mature second-growth and old-growth. Both NMDS and ISA specified associations for Ceanothus thyrsiflorus and Stachys bullata with actively-managed stands. Occurrence of non-natives was low across treatments, though significantly higher on actively managed stands, with the shade intolerant invasive plants, Cortaderia sp. and Myosotis latifolia, occurring exclusively in actively-managed sites.