Poor Biological Condition Research Articles

Stability & Change in a Freshwater Ecosystem

A report by the U.S. Environmental Protection Agency found 46% of rivers and streams and 21% of lakes are in poor biological condition (EPA, 2017). In this 5E standards-based inquiry lesson, students actively engage with the natural phenomena of algal blooms through the introduction of the harmful algal bloom (HAB) that occurred in Lake Erie’s western basin in the summer of 2011. Students make sense of relationships within aquatic ecosystems, using microcosms (miniature ecosystems) containing phytoplankton and zooplankton, and then communicate their findings through a scientific manuscript. This lesson engages students in the three-dimensional learning identified in the Next Generation Science Standards (NGSS) under the standard of HS-LS2, Ecosystems: Interactions, Energy, and Dynamics. More specifically, students address the expectation of HS-LS2-6 when they make sense of how the complex interactions in ecosystems maintain relatively consistent numbers and types of organisms in stable conditions, while changing conditions may result in new ecosystems. This long-term scientific investigation also provides students with opportunities to make sense of aspects of the nature of science, while increasing their science content knowledge and understanding of the practices of science. Evaluation of student work occurs at all stages of the lesson.

The first statewide stream macroinvertebrate bioassessment in Washington State with a relative risk and attributable risk analysis for multiple stressors

We report results from the first statewide assessment of biological health in perennial streams in Washington State. Using a probabilistic sampling survey design, we were able to make unbiased estimates of biological condition of macroinvertebrate communities throughout the state based on 346 sites sampled from 2009 to 2012. Results from randomly sampled sites were classified as either good, fair, poor in comparison with 75 regional reference sites that were sampled concurrently. We determined that approximately 34 percent of stream kilometers assessed were in poor biological condition as measured with a multi-metric index, the Benthic Index of Biotic Integrity. Additionally, we evaluated a variety of chemical and physical habitat stressors known to negatively influence macroinvertebrate communities and determined that poor substrate conditions were the most prevalent and important stressors impacting stream macroinvertebrates, with relative bed stability and percent sand/fines being the most prevalent. A relative risk/attributable risk analysis suggests that improving physical habitat conditions in streams, most notably a reduction in percent sand/fines, will have the greatest impact for improving biological condition for macroinvertebrate communities. It is estimated that approximately 60% of stream kilometers now classified as in poor biological condition in Washington could be improved by reducing the amount of percent sand/fines in the substrate. These results are consistent with those obtained from EPA’s national stream surveys and suggest that poor habitat conditions are the most prevalent stressors impacting stream macroinvertebrates in Washington State.

Improving region-wide ecological condition of wadeable streams: Risk analyses highlight key stressors for policy and management

Unbiased estimates of the current state of target ecosystems and identification of potential causal factors are key to managing stressors over large scales, and for guiding policy and decision makers to set realistic targets and expectations in light of economic pressures. A probability survey design for 176 target wadeable, perennial streams mapped on developed land in the Waikato Region, New Zealand, sampled over three austral summers (2013 to 2015), was used to i) estimate the extent to which “Poor” stressor and biological condition states occur, ii) determine the co-occurrence likelihood of “Poor” biological and environmental condition, and iii) identify and estimate the relative importance of key environmental stressors. The probability survey design also allowed the quantification of uncertainty around mean estimates of extent and risk. These analyses reveal that between 25 and 50% of mapped target stream length can be considered to be in “Poor” condition based on biological indices derived from macroinvertebrate and fish community data. For assessed stressors, Poor condition was estimated for 10 to 50% of the target stream network depending on the stressor. Poor biological condition was likely to co-occur with Poor stressor condition for 10 of the 12 assessed stressors for macroinvertebrate indices, and 5 of the 12 stressors for the fish index. These analyses identify that management actions targeted at improving instream habitat quality, particularly reducing fine sediment deposition, when applied across the entire stream network are likely to yield the most widespread improvement in biological condition indices. Our findings also highlight the importance of extending policy development beyond a singular focus on water quality if ecosystem health objectives are to be met.

Assessing the extent and relative risk of aquatic stressors on stream macroinvertebrate assemblages in the neotropical savanna

Freshwater ecosystems are among the most threatened by human activities, influencing losses of biodiversity. To efficiently address management practices to conserve and restore those ecosystems it is important to correctly identify and quantify the severity and magnitude of anthropogenic stressors degrading freshwater biota. In this study we assessed seven stressors describing poor water quality, physical habitat alteration, and land use by means of the relative risk (RR) and relative extent (RE) approach. The RR measures the co-occurrence probability of high stressor condition and poor biological condition. The RE measures the proportion of stream length in the region in high stressor condition. To obtain accurate estimations of RR and RE we used a probabilistic survey design to select a representative sample of perennial, wadeable and accessible streams within four hydrologic units in the neotropical savanna. Results were evaluated at two spatial scales: local – within each of the four hydrologic units, and regional – all four units combined. From 143 randomly selected sites we inferred our results to a target population of 9466 km of streams. Regionally, we found turbidity, % fine sediments and % agriculture as key stressors associated with poor biological condition. At the local scale, we also found that % pasture and total nitrogen were key stressors of biological condition, but their extent was relatively small. By evaluating both RR and RE we conclude that reducing excess sedimentation on streambeds should be the most effective means of improving biological condition over the region. That finding should guide decision makers and land managers to better focus their efforts and resources on improving biological condition of savanna streams.

Predictive mapping of the biotic condition of conterminous U.S. rivers and streams.

Understanding and mapping the spatial variation in stream biological condition could provide an important tool for conservation, assessment, and restoration of stream ecosystems. The USEPA's 2008-2009 National Rivers and Streams Assessment (NRSA) summarizes the percentage of stream lengths within the conterminous United States that are in good, fair, or poor biological condition based on a multimetric index of benthic invertebrate assemblages. However, condition is usually summarized at regional or national scales, and these assessments do not provide substantial insight into the spatial distribution of conditions at unsampled locations. We used random forests to model and predict the probable condition of several million kilometers of streams across the conterminous United States based on nearby and upstream landscape features, including human-related alterations to watersheds. To do so, we linked NRSA sample sites to the USEPA's StreamCat Dataset; a database of several hundred landscape metrics for all 1:100,000-scale streams and their associated watersheds within the conterminous United States. The StreamCat data provided geospatial indicators of nearby and upstream land use, land cover, climate, and other landscape features for modeling. Nationally, the model correctly predicted the biological condition class of 75% of NRSA sites. Although model evaluations suggested good discrimination among condition classes, we present maps as predicted probabilities of good condition, given upstream and nearby landscape settings. Inversely, the maps can be interpreted as the probability of a stream being in poor condition, given human-related watershed alterations. These predictions are available for download from the USEPA's StreamCat website. Finally, we illustrate how these predictions could be used to prioritize streams for conservation or restoration.

Predictive model based multimetric index of macroinvertebrates for river health assessment

Improving the stability of integrity of biotic index (IBI; i.e., multi-metric indices, MMI) across temporal and spatial scales is one of the most important issues in water ecosystem integrity bioassessment and water environment management. Using datasets of field-based macroinvertebrate and physicochemical variables and GIS-based natural predictors (e.g., geomorphology and climate) and land use variables collected at 227 river sites from 2004 to 2011 across the Zhejiang Province, China, we used random forests (RF) to adjust the effects of natural variations at temporal and spatial scales on macroinvertebrate metrics. We then developed natural variations adjusted (predictive) and unadjusted (null) MMIs and compared performance between them. The core me-trics selected for predictive and null MMIs were different from each other, and natural variations within core metrics in predictive MMI explained by RF models ranged between 11.4% and 61.2%. The predictive MMI was more precise and accurate, but less responsive and sensitive than null MMI. The multivariate nearest-neighbor test determined that 9 test sites and 1 most degraded site were flagged outside of the environmental space of the reference site network. We found that combination of predictive MMI developed by using predictive model and the nearest-neighbor test performed best and decreased risks of inferring type I (designating a water body as being in poor biological condition, when it was actually in good condition) and type II (designating a water body as being in good biological condition, when it was actually in poor condition) errors. Our results provided an effective method to improve the stability and performance of integrity of biotic index.

DIFICULTĂŢI DE DIAGNOSTIC ŞI TRATAMENT ÎNTR-UN CAZ DE MELANOM MALIGN

Malignant melanoma is a rare form of skin cancer, which is only about 3-4% of all skin cancers, but results in a mortality rate up to 65-70%. The vast majority of melanomas are diagnosed in stage 0, I and II, but there were cases when the primary diagnosis of malignant melanoma patients was put directly in stage IV metastatic disseminated lymph nodes, lung, liver, spleen, bone, brain. In the case of a patient with metastatic melanoma, poor biological condition limits the diagnostic and therapeutic possibilities.

Stable isotope estimates of evaporation : inflow and water residence time for lakes across the United States as a tool for national lake water quality assessments

We used water δ2H and δ18O from ca. 1000 lakes sampled in the 2007 U.S. Environmental Protection Agency's National Lakes Assessment (NLA) to assess two hydrological variables—evaporation as a percentage of inflow (E : I) and water residence time (τ) for summer 2007. Using a population survey design, sampled lakes were distributed across the conterminous U.S., and results were scaled to the inference population (∼50,000 U.S. lakes). These hydrologic variables were related to lake nutrients and biological condition to illustrate their usefulness in national water quality monitoring efforts. For 50% of lakes, evaporation was < 25% of inflow, with values ranging up to 113% during the 2007 summer. Residence time was < 0.52 yr for half of the lakes and < 1.12 yr for 75% of lakes. Categorizing lakes by flow regime, 66.1% of lakes were flow‐though lakes (60% or more of the water flows through the lake, E : I < 0.4), 33.6% were restricted‐basin lakes (40% or more of the lake inflow evaporates, 0.4 < E : I < 1), and < 0.3% were closed basin (all water entering the lake leaves through evaporation, E : I > 1). While climate patterns drove some of the spatial patterns of E : I and τ, variation in lake depth and watershed size (influencing precipitation volume) were also significant drivers. Lake hydrochemistry was strongly correlated to E : I and more weakly related to τ. Lakes in poor biological condition (based on a predictive model of planktonic taxa) were significantly more evaporated than lakes in good biological condition.

Investigation of biological condition of fish species in lower Ogun River wetlands, Lagos, Nigeria

The study was carried out to investigate the biological condition of fish species in lower Ogun River wetlands. A total of 175 individual fish belonging to 10 species were collected from artisanal fishermen usingdifferent types of fishing gears. Two biological indices; condition factor “K” and growth exponent “b” obtained from length-weight relationship were used to determine the biological condition of the fishes. The conditionfactor (K) recorded during the study ranged between 0.55 in Liza grandisquamis and 5.61 in Oreochromis niloticus. The growth exponent (b) ranged from 1.48 in Penaus notialis to 5.67 in Gymnarchus niloticus. Theregression coefficient of determination was significant for some of the fish with highest value of R2=0.98 for Sardinella madarensis. The study showed that most of the fish species in the study area are in poor biologicalcondition and exhibit allometric growth.Keywords: Allometric growth, condition factor, growth exponent, length-weight relationship.

A Review of Stream Nutrient Criteria Development in the United States

Elevated nutrients and sediments are the main factors contributing to the poor biological condition measured in over 40% of US waters, highlighting the need for criteria that can aid management efforts to protect or restore the quality of US waters. A large amount of literature on nutrient criteria has been generated since the USEPA called for their development in 1998. Our objective was to examine this peer-reviewed literature to evaluate two main approaches for criteria development in lotic ecosystems: percentile rank and bivariate predictive statistical analyses. The 25th percentile approach has been examined broadly across USEPA-aggregate nutrient ecoregions, and we found that USEPA-suggested criteria for these aggregate ecoregions were often more conservative than criteria estimated using more current regionally focused data based on our compiled data set. Furthermore, 25th percentile estimates were often less than 75th percentile estimates based on reference sites, suggesting that 75th percentile estimates were not more conservative than 25th percentile estimates. Predictive approaches have focused on establishing linear and nonlinear relationships between water quality and algae, macroinvertebrate, and fish communities; attributing causation; and determining whether threshold points exist that can aid in nutrient criteria development. Most of the predictive approaches have occurred at the state or watershed level and may not be directly comparable to USEPA aggregate ecoregions. However, percentile method estimates often fell within the confidence interval of biological threshold criteria estimates, suggesting overlap and some consensus between the two main approaches.

Influence of landscape change on nearshore fisheries in southern Chile

AbstractAt least half of the world's population resides in the coastal zone and the livelihoods of billions of people are affected either directly or indirectly by the production and sustainability of nearshore fisheries. Landscape change, specifically development of tree plantations, is accelerating worldwide as developing countries integrate into global markets to sell goods, offer climate‐mitigation services (carbon), and/or provide renewable energy. These changes can release excess nutrients into adjacent coastal waters causing eutrophication that alters the structure and function of coastal ecosystems. This study examined the relationship between coastal drainage basin land use/land cover change (LCLUC), specifically development of tree plantations, patterns of chlorophyll‐a in nearshore coastal waters, and the biological condition of commercially important shellfish, Concholepas concholepas (loco) in southern Chile. Locos (N = 1374) were sampled across 13 watersheds (35 853 km2) and 42 fisheries management areas (spanning 250 km of coastline). Locos harvested from management areas influenced by tree plantations had approximately 30% more endobiont (shell‐boring) phoronids, almost twice as many endobiont polychaetes and twice as many epibiont (shell‐attaching) barnacles than locos from areas in close proximity to watersheds dominated by native forests (15–20% of the watershed). Phoronid infested locos from coastal waters adjacent to watersheds with tree plantations were of relatively poor biological condition (smaller and narrower in width) and of reduced market value. Our study suggests that tree plantations result in indirect ecological impacts to coastal fisheries (more nutrients and higher phytoplankton biomass, resulting in smaller, low quality locos), and costs are born by coastal fishers (lower prices for locos). Increases in tree plantations could thus potentially significantly impact coastal fisheries worldwide and such problems should be managed as an interconnected network of land use change, oceanic ecosystems, and economic systems that are considered an integrated socio‐ecological system.

Assessing the attributable risks, relative risks, and regional extents of aquatic stressors

A major goal of the national aquatic surveys being conducted by the Environmental Protection Agency in partnership with the states and tribes is to assess the relative importance, at a regional scale, of stressors that impact aquatic biota. The Wadeable Streams Assessment (WSA) was a prototype of these surveys, and it assessed 8 individual water-chemistry, physical-habitat, and landuse stressors in 2 ways. First, the WSA estimated the total length of streams in a region that was deemed to be in poor condition for each stressor considered separately. Estimates of stressor extent describe the prevalence and regional breadth of each stressor’s potential effects. Second, the WSA estimated each stressor’s relative risk, a measure widely used in human epidemiology. Relative risk estimates a stressor’s association with biota in terms of the likelihood that poor stressor conditions and poor biota conditions co-occur in a region’s streams. We describe how the population attributable risk, also borrowed from epidemiology, combines extent and relative risk into a single, overall measure of a stressor’s regional effect. The attributable risk of a stressor is the % reduction in the regional extent of poor biological condition (measured here by the macroinvertebrate index of biotic integrity [MIBI]), that presumably would result from eliminating that stressor. Under the attributable risk assumptions, for example, the WSA data imply that the nationwide extent of poor MIBI conditions would be reduced by an estimated 26% if excess total P were eliminated as a stressor, but only by 3% if excess salinity were eliminated. We also illustrate the attributable risk for the combined effects of multiple, correlated stressors. Last, we discuss how best to interpret and apply attributable risk estimates.

Post mortem changes in glycogen, ATP, hypoxanthine and [formula omitted] absorbance ratio in extracts of adductor muscles from Aulacomya ater ater (Molina) at different biological conditions

1. 1. Post mortem changes in glycogen, ATP, hypoxanthine levels and 260 250 absorbance ratio in extracts of adductor muscles from Aulacomya in different biological condition, were investigated. 2. 2. Glycogen and ATP levels were higher in muscles from specimens in good biological condition. The rate of decrease of both glycogen and ATP was not dependent on the biological condition of Aulacomya. 3. 3. The 260 250 absorbance ratio values in muscle extracts from specimens in poor biological condition were significantly lower ( P < 0.05 at 0 and 24 hr; P < 0.01 at 48, 72, 96 and 120 hr of storage) than in those from specimens in good condition. 4. 4. Irrespective of the biological condition, hypoxanthine levels remained unchanged for 72 hr of storage and increased thereafter.