Effects of Landscape and Riparian Condition on a Fish Index of Biotic Integrity in a Large Southeastern Brazil River

Environmental conditions of a large river in southeastern Brazil were assessed by evaluating fish assemblage structure (index of biotic integrity, IBI), landscape use (forest, pasture, urban area, and tributary water) and riparian condition. A survey of the 338 km-long middle reach of the Rio Paraiba do Sul, containing a large urban-industrial complex, was conducted in two seasons: summer/wet and winter/dry. Fish were sampled with a standardized level of effort twice at seven sites, between March 2001 and April 2002, by gill nets, cast nets, sieves and seines. Riparian condition was evaluated by direct observations, and land use maps were used to assess landscape condition of an 8 km² buffer surrounding each site. IBI scores ranged from 5 to 36 (out of a possible range of 4–40), with lowest values at an urban-industrial landscape, and highest scores upstream and downstream, indicating the river’s recovery capacity. The most appropriate time to assess IBI was during the winter/dry period, when sampling was more effective and the IBI was more sensitive to changes in environmental quality. Landscape use and riparian condition were correlated, and IBI was positively correlated with % pasture, % tributary area, and riparian condition, but negatively correlated with % urban area. In some cases urban areas eliminated riparian woody vegetation, destabilizing site physical habitat structure.     

Large-scale assessments of river health using an Index of Biotic Integrity with low-diversity fish communities

1. Effective tools are needed to measure the ‘health’ of rivers at scales large enough to be useful for management. Indicators for assessing the complex of variables that constitutes river health need to be ecologically based, efficient, rapid and consistently applicable in different ecological regions. 2. A large-scale survey of rivers in New South Wales, Australia provided data to test the Index of Biotic Integrity (IBI). The IBI employs the fish-community attributes, identified using regional and river-size data, expected for a river reach of excellent environmental quality. It uses metrics based on species richness, abundance, community structure and the health of individual fish. IBI metrics were established to suit a relatively low-diversity and unspecialized freshwater fish fauna in south-eastern Australia, totalling 55 species. 3. The IBI was able to discriminate between relative levels of environmental quality within a diverse set of stream systems and four presumptive ecological regions. The index was validated by testing the repeatability of scores, and by comparison of IBI scores at eighty sites with an independent measure of potential catchment condition, the River Disturbance Index. 4. Assessments of metric performance showed that eleven of the twelve metrics contributed satisfactorily. One metric based on trophic guild performed poorly and should be deleted from the index. Six other recommendations are made to enhance the performance of the IBI. 5. Results show that, while all large rivers have been disturbed, rivers in the Murray region and those in many coastal montane areas are particularly degraded. 6. The IBI results presented here demonstrate a validated method for large-scale monitoring of river health based on a fish fauna of limited diversity, in the absence of suitable reference sites.     

An advanced Index of Biotic Integrity for use in tropical shallow lowland streams in Costa Rica: Fish assemblages as indicators of stream ecosystem health

This paper presents an advanced version of the Index of Biotic Integrity (IBI), a multimetric index to indicate ecosystem health. The multimetric index has been adapted in such a way that it not only indicates overall condition but also specific causes of environmental disturbance. The newly developed index (a) uses data of tolerant as well as intolerant species in a single metric to indicate environmental disturbance, (b) does not require knowledge about species from the literature, and (c) can be applied to artificial landscapes.The metrics proposed here consist of indicator species assemblages that are selected directly for their relationship with an environmental component or specific type of environmental degradation. Thus, each metric indicates a type of environmental concern, which enables conservation practices to be targeted more effectively. Species assemblages for each single metric consist of a combination of species that can be negatively and positively related to environmental disturbances, providing a better indication of stream ecosystem health.The area studied was assumed to be too diverse for one single index. Canonical Indirect-Gradient Principal Component Analysis indicated that the optimal division of subindices based on stream typology was for streams with drainage basin sizes <10 km² and >10 km². Pearson Product-Moment Correlations were used to identify relationships between anthropogenic disturbances and the composition and abundance of fish species at impacted as well as undisturbed sites. This index proved to be useful for indicating overall stream ecosystem health as well as local onsite environmental disturbances or the environmental components of greatest concern. This index does require extensive information about measured levels of anthropogenic disturbances with the accompanying composition and abundance of fish species.     

The Planktonic Index of Biotic Integrity (P-IBI): An approach for assessing lake ecosystem health

Using historical (1970) and more recent (1996) Lake Erie plankton and trophic status data, we developed a Planktonic Index of Biotic Integrity (P-IBI) to measure changes in lake ecosystem health. We used discriminant analysis to determine phytoplankton and zooplankton community characteristics (metrics) that distinguished among levels of impairment. Traditional measures of lake trophic status classes (i.e., oligotrophic, mesotrophic, eutrophic), such as chlorophyll a and total phosphorus concentrations, were used to classify sites on a gradient of impairment. We then judged the ability of plankton metrics to distinguish among trophic status classes. Because of the temporal variability found in plankton communities, we conducted analyses on a monthly basis (May–September). For June, July and August we found five unique metrics that could distinguish among trophic status classes. The P-IBI showed an increase in water quality in Lake Erie between 1970 (<3 = eutrophic) and the mid-1990s (1996 and 1997) (3–4 = mesotrophic) (which reflected mean (±standard error) total phosphorus concentrations (μg/L) 1970 > 1996; western basin (41.53 ± 2.68 > 29.75 ± 1.39), eastern basin (14.84 ± 0.82 > 7.74 ± 0.28) and mean (±standard error) chlorophyll a concentrations (μg/L) uncorrected for pheophytin 1970 > 1996; western basin (12.58 ± 1.82 > 5.40 ± 0.22), central basin (5.90 ± 0.36 > 3.17 ± 0.54), and eastern basin (5.17 ± 0.38 > 1.67 ± 0.18)), with declining water quality in the late 1990s (1998 and 1999) (3) and 2002 (<3). We recommend that the techniques used in creating the P-IBI be investigated for determining ecosystem health of other lakes.     

Rapid Survey Technique Using Socio-Economic Indicators to Assess the Suitability of Pacific Island Rural Communities for Kappaphycus Seaweed Farming Development

The literature on economic feasibility of farming seaweeds like Kappaphycus alvarezii in tropical locations is mainly based upon Asian case studies, and often does not take into account social factors in seaweed farming success. Pacific island countries are culturally and economically distinct from Asia, and efforts are now being made to establish seaweed industries here. Past experiences have showed that social factors often outweigh technical factors in determining the success of rural development projects. In addition, Pacific island communities are very diverse in their socio-economic make-up. The particular community chosen for location of a development project is therefore critical to success. Project managers need to recognize in advance the best type of community for seaweed farming development. The objective of this study was to identify socio economic factors that can be used as predictors of project success or failure. Using results of social survey techniques carried out in eight communities within the Fiji Group, a rapid survey technique has been developed which can enable decisions about whether a community is suitable for farming seaweed or not. Though developed from Fiji case studies, the technique can be applied in other rural Asia/Pacific situations.     

Using a Lethality Index to Assess Susceptibility of Tribolium confusum and Oryzaephilus surinamensis to Insecticides

We evaluated knockdown caused by four insecticides: alpha-cypermethrin, chlorfenapyr, pirimiphos-methyl and fipronil against adults of Tribolium confusum Jacquelin Duval, the confused flour beetle and Oryzaephilus surinamensis (L.), the sawtoothed grain beetle. Bioassays were conducted on concrete and metal surfaces. Adults of the tested species were exposed on both surfaces treated with the above insecticides at two doses (low and high). Knockdown assessment was done after 15, 30 and 60 min of adult exposure in the treated surfaces. Also, after 1, 3, 5, 7 and 14 d of exposure, a lethality index was calculated with an equation resulting to values from 0 to 100, where 100 indicated complete mortality and 0 complete survival. We also developed a lethality index by ranking each adult on each surface from 0 to 4, 0: adults moved normally, 1: adults were knocked down, but were able to walk for short intervals, 2: adults were knocked down and unable to walk, but with visible movement of antennae etc., 3: adults were knocked down, with very minimal movement of the tarsi and the antennae and 4: adults were dead (no movement). Knockdown of adults immediately after exposure (15–60 min) was higher for pirimiphos-methyl followed by alpha-cypermethrin, for both dose rates tested and species, but only on the metal surface. The lethality index was nearly 100 for all insecticides after 5d of exposure for O. surinamensis, while for T. confusum the adult lethality index was considerably lower for alpha-cypermethrin, suggesting that that recovery from knockdown occurred. Chlorfenapyr was the only insecticide that was more effective on concrete than on metal, while the reverse was noted for the other three insecticides. These results show that knockdown has different levels, which can be used as indicators of insect mortality or recovery.     

Geography of Invasion in Mountain Streams: Consequences of Headwater Lake Fish Introductions

The introduction of fish into high-elevation lakes can provide a geographic and demographic boost to their invasion of stream networks, thereby further endangering the native stream fauna. Increasingly, remaining populations of native salmonids are concentrated in fragmented headwater refugia that are protected by physical or biological barriers from introduced fishes that originate in the pervasive source populations established at lower elevations. Although fish introduced near mainstem rivers frequently encounter obstacles to upstream dispersal, such as steep slopes or falls, we found that brook trout (Salvelinus fontinalis) dispersed downstream through channel slopes of 80% and 18-m-high falls. Thus, headwater lake stocking provides source populations that may be capable of invading most downstream habitats, including headwater refugia of native fishes. The extent of additional area invasible from lakes, beyond that invasible from downstream, depends on the geography of the stream network, particularly the density and distribution of headwater lakes and their location relative to barriers inhibiting upstream dispersal. In the thermal and trophic environments downstream of lakes, fish commonly grow faster and thus mature earlier and have higher fecundity-at-age than their counterparts in other high-elevation streams. The resulting higher rates of population growth facilitate invasion. Larger body sizes also potentially aid the fish in overcoming barriers to invasion. Trout introductions to high-elevation headwater lakes thus pose disproportionately large risks to native fishes—even when the place of introduction may appear to be spatially dissociated from populations of the native species. Mapping the potential invasible area can help to establish priorities in stocking and eradication efforts. Received 28 March 2000; accepted 9 February 2001.     

Using an Electronic Nose to Rapidly Assess Grandlure Content in Boll Weevil Pheromone Lures

Samples of pheromone lures used in boll weevil,Anthonomus grandis (Boheman),eradication programs are routinely analyzed by Gas Chromatography (GC) to ensure lures are adequately dosed with grandlure,the synthetic aggregation pheromone produced by male weevils.However,preparation of GC samples is tedious,time consuming,and requires a moderate level of experience.We examined the use of a commercially-available electronic nose (e-nose) for rapidly assessing the grandlure contents of lures.The e-nose was trained to recognize headspace collections of grandlure emitted from new lures and after lures were aged under field conditions for 4 d,7 d,10 d,and 14 d.Based on cross-validation of the training set,the e-nose was 82％accurate in discriminating among the different age classes of lures.Upon sampling headspace collections of pheromone from a different set of field-aged lures,the e-nose was ＜50％ accurate in discriminating 4 d,7 d,and 10 d aged lures from the other ageclasses of lures.However,the e-nose identified new and 14 d aged lure samples with 100％ accuracy.In light of these findings,e-nose technology shows considerable promise as an alternative approach for rapidly assessing the initial grandlure contents of lures used in boll weevil eradication programs.     

Natural Shorelines Promote the Stability of Fish Communities in an Urbanized Coastal System

Habitat loss and fragmentation are leading causes of species extinctions in terrestrial, aquatic and marine systems. Along coastlines, natural habitats support high biodiversity and valuable ecosystem services but are often replaced with engineered structures for coastal protection or erosion control. We coupled high-resolution shoreline condition data with an eleven-year time series of fish community structure to examine how coastal protection structures impact community stability. Our analyses revealed that the most stable fish communities were nearest natural shorelines. Structurally complex engineered shorelines appeared to promote greater stability than simpler alternatives as communities nearest vertical walls, which are among the most prevalent structures, were most dissimilar from natural shorelines and had the lowest stability. We conclude that conserving and restoring natural habitats is essential for promoting ecological stability. However, in scenarios when natural habitats are not viable, engineered landscapes designed to mimic the complexity of natural habitats may provide similar ecological functions.     

The Ability of Aquatic Macrophytes to Assess Fish Farm Pollution in Two Salmon Rivers

The wastewater from freshwater fish farming is responsible for important water quality modifications in receiving ecosystems. These point source pollution cause local problems for the management of the freshwater environment, especially in salmon rivers. The aim of this paper is to study the relationship between plant communities and environmental factors in two rivers basins on which seven fish farms are located and to assess the relative part of water pollution compared to other environmental factors involved in water plant distribution. The disturbance due to fish farming wastewater increased both richness and diversity of aquatic plant communities and modified the distribution of 11 aquatic macrophytes. Nevertheless, the main factors involved in the aquatic plant distribution in the whole data set were not the location upstream or downstream from one point source pollution but the belonging to one river system and the habitat physical features. Relevant prediction of macrophytic communities is a useful tool for bioindication purposes but several groups of variables that manifest themselves at different spatial levels must be considered.     

Using Environmental DNA to Estimate the Distribution of an Invasive Fish Species in Ponds

Knowledge of the presence of an invasive species is critical to monitoring the sustainability of communities and ecosystems. Environmental DNA (eDNA), DNA fragments that are likely to be bound to organic matters in the water or in shed cells, has been used to monitor the presence of aquatic animals. Using an eDNA-based method, we estimated the presence of the invasive bluegill sunfish, Lepomis macrochirus, in 70 ponds located in seven locales on the Japanese mainland and on surrounding islands. We quantified the concentration of DNA copies in a 1 L water sample using quantitative real-time polymerase chain reaction (qPCR) with a primer/probe set. In addition, we visually observed the bluegill presence in the ponds from the shoreline. We detected bluegill eDNA in all the ponds where bluegills were observed visually and some where bluegills were not observed. Bluegills were also less prevalent on the islands than the mainland, likely owing to limited dispersal and introduction by humans. Our eDNA method simply and rapidly detects the presence of this invasive fish species with less disturbance to the environment during field surveys than traditional methods.     

A Large-scale Comparative Analysis of Riffle and Pool Fish Communities in an Upland Stream System

Fishes were sampled in riffle and pool habitats at 74 upland localities in the Little River system, southeastern Oklahoma and southwestern Arkansas, U.S.A. I asked how these two habitat-defined communities differed with regard to species abundance and incidence patterns, and how these differences varied along othree environmental gradients: elevation, stream gradient, and stream size. Riffle and pool communities showed distinct and significant differences when ordinated in multivariate space defined by species abundance patterns. Sites with similar pool communities did not have similar riffle communities, and riffle and pool communities responded to environmental gradients in different ways. Elevation was the best predictor of pool community structure, whereas stream size was the best predictor of riffle communities. Overall, riffle habitats had fewer species than pool habitats and formed significant subsets of pool communities at 12 of 74 sites. I predicted that at small stream localities where riffles were unstable, riffle species would form subsets of the pool species communities, and both community types should show high similarities. The presence of faunal subsets was not associated with stream size, but faunal similarities were significantly higher at small stream localities. At the species level, 14 species were significantly associated with pool habitats, while only two were associated with riffle habitats. Riffle and pool communities, although linked by a continuous habitat gradient at the local scale, responded differently to large-scale environmental gradients. Local differences between these communities were predictable based on stream size.     

A New Approach to Assess the Gastrocnemius Muscle Volume in Rodents Using Ultrasound; Comparison with the Gastrocnemius Muscle Index

Introduction

The purpose of this study was to determine the reliability and validity of a new non-invasive ultrasound technique to measure gastrocnemius muscle atrophy after nerve denervation in an animal model.

Methods

In sixteen rodents an eight mm sciatic nerve gap was created. In the following 8 weeks, each week, two rodents were euthanized and the gastrocnemius muscle was examined using two different ultrasound systems and two investigators. The standardized ultrasound measurement protocol consisted of identifying pre-defined anatomical landmarks: 1) the fibula, 2) the fibular nerve, and 3) the junction between the most distal point of the semitendinosus muscle and gastrocnemius muscle. Consequently, we measured the muscle thickness as the length of the line between the fibula and the junction between the two muscles, perpendicular to the fibular nerve. After the ultrasound recording, the muscle mass was determined.

Results

A steep decline of muscle weight of 24% was observed after one week. In the following weeks, the weight further decreased and then remained stable from 6 weeks onwards, resulting in a maximal muscle weight decrease of 82%. The correlation coefficient was >0.96 between muscle diameter and weight using both ultrasound systems. The inter-rater reliability was excellent for both devices on the operated side (ICC of 0.99 for both ultrasound systems) and good for the non-operated site (ICC’s: 0.84 & 0.89). The difference between the muscle mass ratio and the muscle thickness ratio was not more than 5% with two outliers of approximately 13%.

Discussion

We have developed an innovative, highly reliable technique for quantifying muscle atrophy after nerve injury. This technique allows serial measurements in the same animal over time. This is a significant advantage compared to the conventional technique for quantifying muscle atrophy, which requires sacrificing the animal.     

Initial Six-year Expansion of an Introduced Piscivorous Fish in a Tropical Central American Lake

Two populations of the piscivorous fish Gobiomorus dormitor (the guabina) were examined in two separate crater lakes in Nicaragua, Central America. At Lake Apoyo, G. dormitor were introduced in May 1991 by local fishermen and have invaded successfully; at Lake Xiloá, the population is naturally occurring. To provide baseline life history data for G. dormitor in both lakes and to test hypotheses related to population growth and invasion success, this study aimed to (1) document and define the population growth and depth distribution of the fish through video transects in Lake Apoyo; (2) compare diet composition between lakes; and (3) compare life history parameters between lakes, including relative growth rates and reproduction. Videotaped transect studies, designed originally to examine cichlid breeding, began in both lakes in 1990 and have documented the subsequent increase of G. dormitor. Yearly means generally fit the exponential growth model. G. dormitor foraged mainly in shallow waters in Lake Apoyo and preyed mostly upon the atherinid Melaniris cf. sardina throughout seasons. In Lake Xiloá, cichlid fry constituted the majority of the diet overall and cannibalism was more common, although this trend varied with the cichlid breeding season. Relative growth rates were significantly different, based on otolith mass regressions on standard length. Lake Apoyo G. dormitor generally behaved as a successful invading species, displaying exponential growth, year-round reproduction, and higher foraging success than the natural population of Lake Xiloá. Further research is planned to explore the G. dormitor invasion when the population becomes integrated into the community.     

Role of Extracellular Structures of Escherichia coli O157:H7 in Initial Attachment to Biotic and Abiotic Surfaces

Infection by human pathogens through the consumption of fresh, minimally processed produce and solid plant-derived foods is a major concern of the U.S. and global food industries and of public health services. Enterohemorrhagic Escherichia coli O157:H7 is a frequent and potent foodborne pathogen that causes severe disease in humans. Biofilms formed by E. coli O157:H7 facilitate cross-contamination by sheltering pathogens and protecting them from cleaning and sanitation operations. The objective of this research was to determine the role that several surface structures of E. coli O157:H7 play in adherence to biotic and abiotic surfaces. A set of isogenic deletion mutants lacking major surface structures was generated. The mutant strains were inoculated onto fresh spinach and glass surfaces, and their capability to adhere was assessed by adherence assays and fluorescence microscopy methods. Our results showed that filament-deficient mutants bound to the spinach leaves and glass surfaces less strongly than the wild-type strain did. We mimicked the switch to the external environment—during which bacteria leave the host organism and adapt to lower ambient temperatures of cultivation or food processing—by decreasing the temperature from 37°C to 25°C and 4°C. We concluded that flagella and some other cell surface proteins are important factors in the process of initial attachment and in the establishment of biofilms. A better understanding of the specific roles of these structures in early stages of biofilm formation can help to prevent cross-contaminations and foodborne disease outbreaks.     

Core and Satellite Species in Degraded Habitats: an Analysis Using Malagasy Tree Communities

Core-satellite theory predicts that, via the “rescue effect”, widespread, abundant species should have reduced risk of local extinctions. We test this hypothesis in southeastern Malagasy littoral forest using data on distribution and abundance of trees and woody understory vegetation in tropical forest fragments along a disturbance gradient. We partition the mortality risk into two kinds of extinction factors, separately operating at demographic (local) and landscape (regional) scales, contrary to core-satellite predictions, for both trees and woody understory vegetation, that the relative number of core (abundant) species declined significantly with increasing disturbance. In the least-degraded forest fragments there was a strong mode of core species, while in the moderately- and severely-degraded fragments the species distributions were essentially log-normal, lacking a substantial core mode. While the rescue effect mitigates one kind of extinction risk, namely local environmental and demographic stochasticity, it may not counterbalance widespread pervasive sources of mortality. The amount of internal forest fragmentation appears to have a much greater effect on species richness and diversity than either fragment size or shape.     

Development and validation of a Biotic Index for evaluation of environmental quality in the central region of Argentina

The Suquía River (Córdoba, Argentina) has become an important issue because it flows into Mar Chiquita Lake, one of the largest saline lakes in the world. This water body, together with the expansive swamps of the Dulce River on the northern shore and the mouth of Suquía and Xanaes River, is considered one of the most important wetlands in Argentina in terms of biodiversity in a range of freshwater to very saline environments. Nevertheless, the presence of densely populated urban settlements and the increasing environmental impact due to anthropogenic activities characterize the central and lower sections of Suquía River Basin. Fishes are particularly affected and change their distribution and abundance as a consequence of the environmental deterioration. We collected information on fish fauna to develop and validate a Biotic Index to assess degradation of the Suquía River Basin. We classified fish species according to their sensitiveness or tolerance to environmental degradation, based on their distribution and abundance variations along a water quality gradient in order to design a Biotic Index for Suquía River Basin. The set of metrics used in the Biotic Index calculation was conformed by: the abundance of Astyanax eigenmanniorum, Rineloricaria catamarcensis, Gambusia affinis and Cnesterodon decemmacultus, the proportion of sensitive species richness, and the proportion of tolerant species richness. They clearly distinguished between the impaired and referenced sites. We demonstrated that it is possible to use fish as indicators of water quality in Córdoba Province (central part of Argentina) in order to carry out rapid and relatively inexpensive monitoring and conservation programs. The application of this Biotic Index showed that fish assemblages reflect the watershed conditions and are sensitive to changes in water quality across the environmental gradient.     

Evaluation of Two Monitoring Approaches to Assess Effects of Waste Water Disposal on Histological Alterations in Fish

An active monitoring (caging experiment) and a passive monitoring (sampling of wild fish) were performed to investigate the effects of effluent from a sewage treatment works (STW) on brown trout (Salmo trutta) by histopathological examinations of the skin, gill, liver and kidney. Histopathological lesions were evaluated according to a standardised assessment tool, which allows calculation of indices for every organ. According to the results of both monitorings, trout exposed to river water supplemented with treated waste water from the STW Lyss showed higher histopathological indices than trout caught upstream of the discharge point of the STW or kept in river water only. These results indicate a negative effect of treated waste water from the STW on the histopathological status of the examined organs of brown trout. Both monitoring approaches revealed the liver to be the most affected organ compared with reference fish. However, data from the two monitoring approaches were not completely consistent: histologically the gills were the most sensitive organ to the effects of treated waste water in the active monitoring, but were not affected in the passive monitoring. The data provide relevant information about both the comparability and the pros and cons of the two monitoring approaches to assess effects of pollution on histopathological alterations in fish.     

Development of an Item Scale to Assess Attitudes towards Domestic Dogs in the United Republic of Tanzania

ABSTRACT

Domestic dogs are important sources of rabies exposure for humans in the developing world. Control of the disease in endemic areas relies on the vaccination of owned dogs, and thus owners' attitudes and behavior towards household dogs may be of relevance to rabies control programs. However, none of the instruments used to evaluate attitudes towards companion animals have been validated for use in developing countries. In this paper, we present the development of an item scale to measure attitudes towards owned dogs in Tanzania. We assess the scale's reliability and validity, and conduct a preliminary analysis of factors affecting respondents' attitudes. Twelve 5-point Likert scale items were selected from an item pool during the pilot phase. Following administration of these items to 824 dog owners across 12 study sites in Tanzania, two subscales were derived, representing the acceptance of dogs as equals and physical interactions with household dogs. Both subscales showed acceptable levels of reliability and concurrent validity, although the latter estimates were found to be influenced by interviewer identity. Male respondents had significantly higher scores on both subscales than females, and Muslim respondents showed more positive attitudes towards dogs as equals than did Christians. Among those respondents who were also the heads of their households, those whose dogs were vaccinated against rabies had a more positive attitude towards dogs as equals. It is hoped that the derived item scale will serve as a basis to further understanding of the motivational considerations of attitudes towards dogs in developing countries, and how these may influence aspects of dog ownership, welfare, and disease control.