Different Degrees Of Human Impact Research Articles

Measuring plant functional specialization in urban environments with Grime's CSR strategies

AbstractQuestionSpecialization refers to the degree of niche breadth of a species. Generalist species are able to persist in a broad range of habitats, whereas specialist species are adapted to a restricted range of environmental conditions. Cities host a great heterogeneity of habitats with variable degrees of human impact. This is generally reflected in the functional composition of the urban floras. The aim of our study is thus to explore whether the degree of functional specialization of urban plant assemblages varies among habitats subject to different degrees of human impact and disturbance regimes.LocationThirty‐two cities in Central Europe with more than 100,000 inhabitants.MethodsWe used a data set containing plots of urban floras sampled in seven habitat types within each city: historical city square, boulevard, residential area with a compact building pattern, residential area with an open building pattern, city park, early successional site, and mid‐successional site. These habitats differ in the level of human impact, ranging from moderately urbanized suburban habitats to the most urbanized habitats in the city center. For each plot, we calculated a recently introduced specialization index, which is based on the application of concentration measures to Grime's community‐level mean CSR strategies.ResultsAlong the urbanization gradient, from peripheral to central habitats, we observed a marked intensification in the degree of functional specialization of urban habitats, which is primarily attributable to an increase in the selection of ruderal species.ConclusionsUrban ecosystems are characterized by a wide variety of human impacts that affect the functioning of the resident species. Considering cities as heterogeneous systems is thus of paramount importance for understanding the mechanisms that drive the assembly of urban floras.

How natural and anthropogenic factors should drive microplastic behavior and fate: The scenario of Brazilian urban freshwater

Brazil maintains its position at the top of the global ranking of plastic producers, yet recycling efforts have been incipient. Recent data reveals an annual production of approximately 14 million tons of plastic waste, not accounting for the surge in the usage of plastic masks and related materials due to the COVID-19 pandemic. However, what remains largely unreported is that over half of post-consumer plastic packaging in Brazil is managed without any monitoring, and it remains unclear how this will contribute to the occurrence of plastic waste and microplastics in Brazilian freshwaters. This scenario requires the consideration of several other crucial factors. Studies have been carried out mainly in marine and estuarine waters, while data on freshwaters are lacking. Brazil has continental dimensions and the highest water availability on the planet, yet the demand for water is greatest in regions with medium to low supply. Many densely populated Brazilian urban areas face chronic flood problems, possess inadequate levels of wastewater treatment, and display inadequate solid waste management practices. Consequently, urban freshwater with tropical characteristics in Brazil presents an intriguing scenario and is complementary to the most commonly studied marine environments. In this study, we explore the nuances of pollution in Brazilian urban freshwater and discuss how various parameters, such as organic matter, suspended solids, temperature, and pH, among others, influence the behavior of microplastics and their interactions with organic and inorganic contaminants. Furthermore, we address how microplastic conditions, such as biofouling, the type of plastic, or degradation level, may impact their behavior. By analyzing how these conditions change, we propose priority themes for investigating the occurrence of microplastics in Brazilian urban freshwater systems under different degrees of human impact. Ultimately, this study aims to establish a network dedicated to standardized monitoring of microplastic pollution in Brazilian urban freshwaters.

How do urban green spaces increase well-being? The role of perceived wildness and nature connectedness

Nature connectedness is recognised for its potential to promote pro-environmental behavior and well-being. While urban green spaces are the main form of direct contact with nature for many people, it is largely unclear which types of natural settings and qualities in urban areas most effectively strengthen human relationships with nature. Wilderness is increasingly acknowledged as contributing to higher biodiversity in urban areas and has long received attention from the arts and sciences for its range of well-being benefits. The present study investigates the effects of walking in two different natural settings on people's nature connectedness and well-being. Eighty-four participants were randomly assigned to a walk in an urban forest or a landscape park, which represent different degrees of human impact on the landscape. Both settings increased positive affect, decreased negative affect, and restored attention capacity. Against our expectation, participants walking in the urban forest did not show higher levels of nature connectedness or well-being compared to those in the landscape park. Furthermore, the urban forest was not perceived as wilder than the landscape park. The degree to which people perceived the environments as wild was positively associated with nature connectedness. The findings further suggest that perceived wildness may increase positive affect through nature connectedness. The experience of connection with nature may be an important mechanism by which nature exposure enhances well-being. We conclude that individual perceptions of nature can influence the degree to which well-being benefits are gained in urban green spaces.

Pattern and pace of morphological change due to variable human impact: the case of Japanese macaques

Human impact influences morphological variation in animals, as documented in many captive and domestic animal populations. However, there are different levels of human impact, and their influence on the pattern and rate of morphological variation remains unclear. This study contributes to the ongoing debate via the examination of cranial and mandibular shape and size variation and pace of change in Japanese macaques (Macaca fuscata). This species is ideal for tackling such questions because different wild, wild-provisioned, and captive populations have been monitored and collected over seven decades. Linear measurements were taken on 70 skulls from five populations, grouped into three ‘human impact groups’ (wild, wild-provisioned, and captive). This made it possible to investigate the pattern and pace of skull form changes among the human impact groups as well as over time within the populations. It was found that the overall skull shape tends to differ among the human impact groups, with captive macaques having relatively longer rostra than wild ones. Whether these differences are a result of geographic variation or variable human impact, related to nutritional supply and mechanical properties of the diet, is unclear. However, this pattern of directed changes did not seem to hold when the single captive populations were examined in detail. Although environmental conditions have probably been similar for the two examined captive populations (same captive locality), skull shape changes over the first generations in captivity were mostly different. This varying pattern, together with a consistent decrease in body size in the captive populations over generations, points to genetic drift playing a role in shaping skull shape and body size in captivity. In the captive groups investigated here, the rates of change were found to be high compared to literature records from settings featuring different degrees of human impact in different species, although they still lie in the range of field studies in a natural context. This adds to the view that human impact might not necessarily lead to particularly fast rates of change.

Towards Conservation of Genetic Variation of Tropical Tree Species With Differing Successional Status: The Case ofMansonia altissimaA. Chev andTriplochiton scleroxylonK. Schum

Two important West African timber tree species with differing successional status, Mansonia altissima A. Chev and Triplochiton scleroxylon K. Schum were investigated in this study. Triplochiton scleroxylon is a pioneer species found in open forests, whereas Mansonia altissima is a nonpioneer light-demanding tree species occurring in closed forests. Amplified fragment length polymorphism markers were used to compare the genetic diversities of these two timber species in stands with different degrees of human impact (isolated forest patch, logged forest, farmland, plantation, and primary forest). Contrasting effects of human impact on genetic diversity were detected for these two timber species. The results suggested severe effects of human impact on the genetic diversity of Mansonia altissima, a nonpioneer species. However, no adverse effect was recorded in Triplochiton scleroxylon, a pioneer species. These findings indicate that nonpioneer tree species could be more prone to genetic erosion than pioneer tree species as a result of adverse human impacts. Therefore, conservation of genetic diversity in both pioneer and nonpioneer tree species populations would likely necessitate different measures.

Feeding habits of four sympatric sharks in two deep-water fishery areas of the western Mediterranean Sea

The study of the feeding ecology of marine predators is crucial to understanding their ecological roles and advancing our knowledge of marine ecosystem functioning, especially in highly human-impacted areas. Here, we examined the trophic ecology of three abundant demersal sharks, the velvet belly lantern shark Etmopterus spinax, the blackmouth catshark Galeus melastomus and the small-spotted catshark Scyliorhinus canicula, and the rare kitefin shark Dalatias licha of the western Mediterranean Sea. Data were obtained from two deep-water areas with different degrees of human impact: a fishery restricted area (FRA) in the Gulf of Lions and a highly human-impacted area in the Catalan Sea (non-FRA). We combined analyses of individual stomach contents and stable isotope values from different individuals of each shark species. Our results revealed that D. licha is a predator located higher up on the food web, while G. melastomus, E. spinax and S. canicula are located in lower trophic positions. These results confirm that shark species play important and, most likely, complementary roles as predators in the western Mediterranean Sea. Results also revealed that despite some differences in the diet of the shark species, as revealed by the stomach contents, in the long term (isotopic results) the four species showed similar diet habits and similar trophic relationships in both FRA and non-FRA. This may be due to the fact that despite the fishing regulations in the FRA area, the population of the prey species probably do not vary between the two areas.Overall, this study provides new insights into the trophic ecology of these sharks and contributes to an understanding of their ecological roles within the community.

Management practices may lead to loss of arbuscular mycorrhizal fungal diversity in protected areas of the Brazilian Atlantic Forest

Abstract The symbiotic arbuscular mycorrhizal (AM) fungi are among the ecologically most significant organisms in terrestrial ecosystems, but little is known about how soil AM fungal community composition responds to conservation management and different degrees of human impact on natural ecosystems. The objective of this study was to evaluate effects of the management practices on the AM fungi community structure in protected areas of the Atlantic Forest in Northeast Brazil. During two seasons we assessed AM fungal diversity and mycorrhizal root colonization status in five strict-protected and five sustainable-use areas along a 900 km transect. The sampling effort was sufficient to recover more than 85% of the AM fungal species present in the protected areas. Fifty-six AM fungal species and morphotypes were identified. Most species belonged to Glomerales and Gigasporales, but all orders of Glomeromycotina were registered. Species diversity and mycorrhizal colonization were significantly higher in the strict-protection management areas, though the areas had the same richness and spore density. Seasonality and spatial distances did not affect the AM fungal community composition. Our results show that the conservation management, vegetation and soil characteristics are important local factors influencing AM fungal communities. This work provides a better understanding of AM fungal community structure in natural ecosystems and provides insight into distribution patterns at a broad landscape scale.

Selective logging alters allometric relationships of five tropical tree species in seasonal semi-deciduous forests

In selectively logged forests, trees are more likely to expand their diameters (D) at the expense of height (H) growth, resulting in variations in H:D relationships. This study examines how selective logging affects the H:D allometric relationships of five common tree species and whether the effects vary with functional groups (shade-intolerant or shade tolerant) in seasonal semi-deciduous forests. Individuals of five species in a 3000 m2 (0.3 ha) plot were marked and heights and diameters recorded. Most of the species, with one exception, showed greater investment in diameter per increment of height compared to an unlogged forest, possibly because of the greater light available. This study shows the effects of selective logging on species populations as evidenced by increases in H:D ratios. Comparison of forest fragments with different degrees of human impact is important because it allows us to understand the differences in architectural characteristics caused by selective logging.

SPECIES DIVERSITY OF PLANKTONIC ROTIFERS IN LOTIC ECOSYSTEMS: A CASE OF STUDY OF DANUBE, SFANTU GHEORGHE BRANCH

Rotifers are known as cosmopolitan organisms, found in high density in most waters, often representing the dominant group in terms of species diversity and abundance in the zooplankton community. Since the functionality of an ecosystem is closely related to the diversity of communities, analysis of rotifers assemblage may be a useful tool in understanding the mechanisms of the spatial and temporal changes on this level. Data were collected from 2008 until 2010, in distinct areas of Danube, Sf ntu Gheorghe branch with different degrees of human impact. Sf ntu Gheorghe river branch has distinct features conferred by the construction of new canals and cutting off the meanders. Due to these regularization changes, a complex of ecosystems with different features resulted. The impact of engineering may determine a reduction in species diversity and abundance in the new ecosystems. The canals of Sf ntu Gheorghe branch presented the lowest value of the species richness and diversity indices in comparison with the other two areas. The constant species belong to Brachionus, Keratella, Asplanchna, Synchaeta genus. The branch environmental conditions allow the development loricate species and soft-bodied type, the dominant species belonging to Brachionidae family. This study reveals a close resemblance between natural sectors and meanders in terms of diversity and abundance of the rotifer assemblage. Opposites, in the newly created canals, the species richness and abundance registered a decreasing reflecting the impact of human interventions on the ecological system.

Assessment of the Abundance and Diversity of Calliphoridae and Sarcophagidae (Diptera) in Sites With Different Degrees of Human Impact in the Iberá Wetlands (Argentina).

The aim of the present study was to explore the diversity and describe the spatial distribution of Calliphoridae and Sarcophagidae along an urbanization gradient in the Iberá Wetlands. The flies were collected at 18 sampling points, three per site. In total, 3,318 flies were collected (3,077 blow flies and 241 flesh flies), distributed in 13 genera and 33 species. Calliphoridae was the most abundant, comprised 92.74% of all adult flies. Chrysomya albiceps (Wiedemann), Cochliomyia macellaria (F.), Chrysomya megacephala (F.), and Chrysomya putoria (Wiedemann) were the most abundant species, representing 82.21% of the total sample. The genus Oxysarcodexia Townsend was the most diverse with 10 species represented. The abundance of exotic species represents 62.85% of the total sample, showing a reduction toward less disturbed sites. The results of this study indicated that sites with intermediate impact had higher diversity than those where the disturbances are high or absent. Our findings provide the first assessment of Calliphoridae and Sarcophagidae diversity in the area of the Iberá Wetlands.

Assemblage of Necrophagous Diptera in Atlantic Insular Environments and Response to Different Levels of Human Presence.

Islands act as natural laboratories for ecological studies to explain bioinvasion processes and, in this scenario, necrophagous Diptera have never been used as model organisms. This study aimed to (i) describe assemblages of necrophagous Diptera (Calliphoridae and Sarcophagidae) in two insular environments of different origins and distances from mainland, (ii) investigate the effect of anthropogenic impact on the assemblage of carrion flies, (iii) to quantify the establishment of invasive species in the two islands, and (iv) to infer about the conservation status of the islands based on the ecological parameters. Sampling was performed in 2011-2012, in the dry and rainy season. Insects were collected by using traps with chicken liver or sardine baits. In each island, environments exposed to different degrees of human impact were sampled. Ecological analyses were carried out to characterize the assemblages of Calliphoridae and Sarcophagidae, with emphasis on the relation between native and invasive species. In total, 99,862 adults of 21 species of blow flies and flesh flies were collected. Overall abundance in the oceanic island was higher than in the continental island, although the richness of species was higher in the latter. The type of bait did not influence diversity of species sampled in either island. No difference was observed in total richness of both families according to the gradient of anthropogenic impact, in both islands. The invasive species Chrysomya megacephala (Fabricius) was classified as dominant in all environments, irrespective of the anthropogenic impact, which raises concern about the conservation status of each island.

Spatio-temporal variability of Borer Polychaetes in Posidonia oceanica beds and its relation to meadow structure

Posidonia oceanica forms an extremely productive and complex ecosystem in the coastal Mediterranean Sea providing a suitable habitat for hundreds of plant and animal species. Among motile invertebrates associated to Posidonia meadows, polychaete borers of the plant sheaths represent a unique group which exploit a peculiar microhabitat. They belong to the family Eunicidae with three dominant species, Lysidice collaris, L. ninetta and L. unicornis. Due to their strong association with Posidonia shoots, these animals are particularly suitable to study the plant and animal spatial relationships and their pattern of variability. The aim of this work was to evaluate the frequency of occurrence of these animals (Index of Borer, IB) at different spatial and temporal (summer vs winter) scales in two Posidonia meadows off the Ischia Island (Gulf of Naples, Italy), which are exposed to different degrees of human impact and of hydrological conditions. Results showed IB values of L. collaris (the most abundant species) significantly different between meadows and at scales from 10s to 100s of meters, as well as between summer and winter. The IB of L. ninetta showed significant differences only at scales of 10s of meters while, on the contrary, the IB of L. unicornis (the less abundant species) did not show variability at any spatial and temporal scales. Most of the variance was at the more impacted and less water movement exposed meadow, suggesting higher level of small and intermediate scales of patchiness of borers at this meadow. These variation patterns are discussed in relation to local environmental differences between the studied Posidonia beds.

Assessment of landslide age, landslide persistence and human impact using airborne laser scanning digital terrain models

Bell, R., Petschko, H., Röhrs, M. and Dix, A. Assessment of landslide age, landslide persistence and human impact using airborne laser scanning digital terrain models. Geografiska Annaler: Series A, Physical Geography, 94, 135–156. doi:10.1111/j.1468‐0459.2012.00454.xABSTRACTLandslides occur worldwide and contribute significantly to sediment budgets as well as to landform evolution. Furthermore, they pose hazards and risks to people and their goods. To assess the role of landslides, information on their age or persistence (i.e. the length of time the morphological characteristics of a landslide remain recognizable in the terrain) is essential. In this study, the potential of airborne laser scanning digital terrain models (ALS DTMs) is analysed for estimating landslide age, landslide persistence and human impact. Therefore, landslides in two study areas, Swabian Alb in Germany and Lower Austria in Austria, are mapped from hillshades of ALS DTMs and combined with historical information on landslide occurrence. It is tested whether the modification of the geomorphological features of landslides can be used to assess landslide age. In the Swabian Alb older landslides might show fresher features than younger ones because of different degrees of human impact, natural erosion and different histories of landslide reactivation. Estimated persistence times range between 27 and 320 years but are minimum values only. In Lower Austria four landslides show estimated minimum persistence times between 4 and 28 years. In Lower Austria 27 landslides disappeared in less than 7 years after occurrence mainly because of planation by farmers. The results show no clear trend in landslide persistence, neither regarding landslide magnitude, nor regarding land use. However, it is evident that human impact plays a major role in landslide persistence.

Regeneração e estrutura populacional de jatobá-da-mata (Hymenaea courbaril L.), em dois fragmentos com diferentes graus de perturbação antrópica

O objetivo do estudo foi avaliar a estrutura populacional e os efeitos da intensidade luminosa no recrutamento de jatobá-da-mata (Hymenaea courbaril L.) em dois fragmentos de Mata de Galeria não-inundável, com diferentes graus de perturbação antrópica. Foi assumida a hipótese de que as populações diferem nas classes de tamanho (diâmetro e altura) e abundância dos indivíduos entre os fragmentos e o recrutamento responde às diferenças de luminosidade disponível no sub-bosque. Como espécie clímax dependente de luz amplamente distribuída e adaptada a ambientes heterogêneos, espera-se uma maior abundância e regeneração de jatobá-da-mata no fragmento com maior incidência luminosa. Em cada fragmento foram utilizadas 25 parcelas permanentes, alocadas de forma aleatória ao longo de transectos entre a borda da mata e o leito córrego posicionados perpendicularmente à margem do córrego. As plântulas foram amostradas no interior de cada parcela, a partir de quatro sub-parcelas de 2x2 m ao longo de uma linha central no comprimento da parcela. No sub-bosque, em cada sub-parcela, a radiação fotossinteticamente ativa foi determinada e os valores de transmitância (T%) foram obtidos a partir das medidas a pleno sol fora da mata. Nos dois fragmentos o maior número de indivíduos se concentrou nas menores classes de tamanho, mas não foi obtido um bom ajuste à distribuição exponencial negativa (J invertido). A análise de regressão linear indicou que tanto o diâmetro como a altura dos indivíduos jovens (mediana/parcela) apresentaram, respectivamente, respostas positivas em relação ao efeito da T% (F=11,58-14,82(1,40); p<0,01). Foi observada menor abundância de jovens no fragmento mais perturbado que pode ser resultado de eventos de fogo no passado recente. Apesar de mais abundantes, os jovens no fragmento conservado, com dossel mais fechado, e consequentemente, com menos luz disponível no sub-bosque, apresentaram distribuições de tamanho semelhante às plântulas. Esse resultado sugere que o jatobá-da-mata é capaz de regenerar e recrutar em ambientes sombreados, mas o crescimento é limitado pelas condições de pouca luminosidade. .

Assessing egret ecological safety in the urban environment: A case study in Xiamen, China

In general, wildlife is facing increasing threats from rapid urbanisation in China. Ecological safety for wildlife requires an ecosystem that provides the conditions necessary for sustaining life. In this paper, two major breeding habitats and ten typical foraging habitats of egrets living in the urban environment were selected to assess the extent to which the needs of egrets can be satisfied and maintained. Ecological suitability and impacts from humans are the two major factors affecting egret ecological safety. An ecological indicator system was adopted to assess the ecological suitability of areas. Different land-use types were used to represent different degrees of human impact on the egret habitats, by employing a geographic information system. The results show that the two breeding habitats are at a safe level, while the ten foraging habitats are on the whole marginally safe. Full attention should be given to the conservation of wildlife foraging habitats in Xiamen Island.

Phytoplankton dynamics in two tropical rivers with different degrees of human impact (southeast Brazil)

AbstractPotamoplankton attracts little research attention worldwide and this also holds true in Brazil, despite its numerous river systems. The origin and maintenance of phytoplankton populations in these systems have not been well studied. We analysed biological, physical and chemical parameters of the Paraibuna and Pomba rivers to identify the main driving forces behind temporal and spatial phytoplankton patterns. Both systems are located in the southeast, the most populated region. These rivers are similar in climate and geomorphology, and have become eutrophic due to the increase in the human population of the region, especially in Paraibuna River catchments. Twelve and eleven stations were, respectively, sampled during the dry and rainy seasons in the Paraibuna and Pomba rivers. The seasonal pattern of abiotic and biotic variables was related to the increase in the discharge and dilution caused by the rainy period. However, human influences such as the presence of a reservoir and sewage inflow were important to distinguish the rivers. The phytoplankton community of Paraibuna River was influenced by Chapéu D'Uvas Reservoir, which was dominated by a toxic population of Cylindrospermopsis raciborskii. Pomba River phytoplankton was typical of the lotic tropical systems. Phytoplankton functional groups in both rivers were those commonly found in turbid and turbulent shallow lakes. Although the functional group approach was originally described for lentic environments, our data support this approach for lotic community patterns. Copyright © 2007 John Wiley & Sons, Ltd.

A relation between historical forest use and current dead woody material in a boreal protected old-growth forest in Finland

Assessing the human impact on the naturalness and vegetation characteristics of protected areas is one of the key issues when designing forest conservation networks in Fennoscandia. We studied the small-scale, detailed relationship between forest utilization history and the current availability of dead woody material in a protected old-growth forest area in North Karelia, eastern Finland. From the study area of 32.4 ha, all the stumps (diameter ≥ 5 cm and height < 1.3 m, classified as natural, man-made and of undetermined origin) were measured using 25 x 25 m sub-plots. Standing and fallen dead trees (dbh ≥ 5 cm) were measured on 50 x 50 m plots in an area of 7.8 ha. The average number of stumps was 130 per ha, and over half of the stumps were classified as man-made. However, the historical documents since the 1910s showed no logging in the area: some of the largest man-made stumps probably originated from an earlier time, but most of those stumps were made considerably later. The variation in the total number of stumps (per ha) was great (range 0–560/ha, 0–16 m2/ha), with no clear clustering in space. However, clustering of man-made stumps was detected. The average volume of pooled standing and fallen trees was 84 m3/ha, with a range of 37–146 m3/ha. The other noticeable man-made disturbance besides logging was notching of aspens, which has a scatteredly significant influence on the amount of dead trees. In conclusion, the protected old-growth forest was not as a whole in a natural state but showed different degrees of human impact from virtually untouched patches to quite heavily managed patches. The results suggest that the number of man-made stumps may be a relatively quick and easy method of assessing the naturalness of woody biomass structure in the Fennoscandian boreal forests.

Comparing diatom species, genera and size in biomonitoring: a case study from streams in the Laurentians (Québec, Canada)

1. We studied the distribution of epilithic diatoms in streams subjected to different degrees of human impact in order to evaluate their potential as bioindicators for environmental changes such as nutrient enrichment and acidification.2. Three descriptors of the diatom assemblages were tested with respect to their potential to predict environmental changes: species composition, genus composition and size distribution.3. Water colour and pH explained the largest amount of variation in diatom assemblages. According to ordination analyses, water colour explained variations in size distribution (42%) better than those in generic (25%) or species composition (8%). On the other hand, pH was not correlated with size distribution while a significant fraction of variation was explained by species (11%) and especially generic (18%) composition. Only species composition responded to changes in phosphorus and grazer biomass, however.4. Size distribution and coarse (genus level) taxonomic analyses sometimes outperformed fine taxonomy in describing the response of diatom assemblages to colour and acidity. In view of the simplicity of these alternative descriptions of diatom assemblages, their potential for routine stream monitoring should be further explored.

Exploration of the utility of fluctuating asymmetry as an indicator of river condition using larvae of the caddisfly Hydropsyche morosa (Trichoptera: Hydropsychidae)

Organisms are subject to three types of morphological asymmetry: Directional Asymmetry, Antiasymmetry and Fluctuating Asymmetry, but only the latter (FA) is related to the environmental stress acting upon individuals during their development. Larvae of Hydropsyche morosa from five rivers in Ontario, Canada, each exhibiting different degrees of human impact, were examined for FA. Specimens were obtained from collections in the Royal Ontario Museum dating back to 1951, and from fresh collections to 1999. Twelve morphological characters were assessed on both the left and right sides of 297 larvae, and eight of them demonstrated FA. There was a tendency to increase the levels of FA over time. Levels of nitrogen, conductivity and chloride in the river water, used as an index of pollution, were significantly and positively correlated with increasing incidence of FA in four of the characters, the remainder were independent of pollution.