Assessing the ecological values of rivers: an application of a multi-criteria approach to rivers of the South Coast Region,Western Australia

There is a growing awareness that in the light of increased threats, Australia’s freshwater ecosystems of highest value need to be protected. This implies that a consistent and comprehensive system for the classification of freshwater systems in terms of their ecological values is required for conservation planning. Despite earlier steps taken to develop appropriate methodologies for prioritising Australian waterways for protection, there is, as yet, no nationally agreed method for prioritising waterways in Australia based on their ecological values. Using the core criteria of naturalness, representativeness, diversity, rarity and special features, this paper describes the development of a framework of criteria, indicators and measures for the identification of high conservation value aquatic ecosystems, and trials this system by undertaking a comparative assessment of the ecological values of river systems in the South Coast region, Western Australia. A total of 33 river systems located in two aquatic bioregions were successfully ranked according to their ecological value, confirming that the development and implementation of a relatively simple system for assessing ecological values of Australian rivers shows promise, and that core criteria identified previously in the literature provide a good starting point for assessing ecological values of Australian aquatic ecosystems.     

Effects of an experimental environmental flow release on the diet of fish in a regulated coastal Australian river

Environmental flow rules are developed to provide a flow regime necessary to maintain healthy river and floodplain ecosystems in rivers regulated for human uses. However, few studies have experimentally assessed potential ecological mechanisms causing declines in the health and productivity of freshwater fish assemblages in regulated rivers to inform the development of appropriate environmental flows. We tested whether an experimental flow release in a regulated tributary of the Hunter River, Australia, altered the diet of two widely distributed fish species (Australian smelt Retropinna semoni and Cox’s gudgeon Gobiomorphus coxii) compared with data from unregulated reference and regulated control tributaries. Neither species had significant differences in the number of prey taxa ingested, gut fullness or composition of gut contents due to the environmental flow release (EFR). The diet of R. semoni did not differ significantly between regulated and unregulated tributaries in either catchment. However, the diet of G. coxii differed in only one of the two pairs of rivers consistently across all sample times. Assuming the EFR was sufficient to alter the composition of prey available for consumption by the fish species studied, our findings imply that functional indicators, such as the diet of generalist higher-order consumers, may be more suitable indicators of long-term flow regime change rather than short-term flow events.     

Linking land to ocean: feedbacks in the management of socio-ecological systems in the Great Barrier Reef catchments

The Great Barrier Reef (GBR) off Australia’s northeast coast is one of the natural wonders of the world. As a consequence it has high value, not only for biodiversity, but also for tourists who come to see the GBR and the biodiversity associated with it, bringing in over A$3.5B per annum to the Australian economy. However, there are a number of natural and anthropogenic factors that are threatening the health of the reef ecosystems. One of the major anthropogenic factors is the impact of sediments and nutrients that run off the land, via the rivers, into the lagoon of the reef. Extensive beef production is one of the major land uses of the GBR catchment, and brings in over $1B to the national economy annually and employs nearly 9,000 people, many of them in rural communities. Over 70% of terrestrial sediments and nutrients deposited in the GBR lagoon affecting the health of vulnerable reef ecosystems originate from the extensive grazing lands of Queensland’s interior. Recent research indicates that the quantity of sediments and nutrients lost from these grazing lands is strongly dependent upon grazing management practices; grazing leads to degradation of soil and vegetation resources, reduced infiltration and vegetation production. This has led to a growing concern amongst the Australian public about the environmental performance of the beef industry and increasing pressures on graziers to change their management practices to decrease the off-farm impacts. Given the constraints within the system improvements in water quality draining into the GBR lagoon can best be achieved by demonstrating the productivity and economic benefits of science-based improved grazing management practices for graziers, leading to “AllWin” outcomes for all concerned. In the longer term, only when the range of stakeholders involved approach catchments as linked biophysical, social and economic systems, will truly integrated adaptive catchment management be applied to the GBR.     

Characterization,Ecological Status and Type-specific Reference Conditions of Surface Water Bodies in Wallonia (Belgium) using Biocenotic Metrics based on Benthic Invertebrate Communities

The river types in Wallonia (Belgium) were defined according to the system B of the European Water Framework Directive (WFD) taking into account obligatory and optional factors synthesized in three criteria: ‘size’, ‘slope’ and ‘natural region’. Under the hypothesis that benthic invertebrate assemblages would be specialized according to river type, a set of 627 faunal samples originating from an 11-year sampling period was tested to characterize river types with faunal assemblages. A multivariate approach led to gather 23 river types into seven groups exhibiting similar faunal assemblages. Using biocenotic metrics based on benthic invertebrate assemblages (e.g., the French standard IBGN), type-specific reference conditions and ecological status class limits were defined for each ‘natural’ river type group. Ecological potential was defined for heavily modified and for artificial (i.e., man-made canals) types. An ‘ecological status’ evaluation strategy was therefore developed and applied in the southern – and more natural – part of Wallonia, where many reference sites were available. In the northern part of Wallonia (i.e., the ‘Loess region’) where no high quality site was available, the expert judgement took a larger part in the definition of the reference conditions and of the ecological status class limits, in addition to the calculations. Two independent distribution gradients of taxa assemblages resulted from multivariate ordination: a first ‘saprobity axis’, as the taxa-sensitivity to organic contamination was increasing from ‘very resistant’ taxa (mainly located in the ‘Loess region’) to ‘sensitive’ and ‘very sensitive’ taxa (from the river types belonging to the Condroz, the Famenne, the Arden and the Jurassic regions) and a second axis characterizing the Meuse-specific faunal assemblage, gathering exotic species and typical limnophilous taxa of large heavily modified rivers. The ecological status monitoring management system developed in this study – i.e., the definition of faunal river type groups, related reference conditions and ecological status class limits – represents a proposal to be integrated in the ecological status assessment of biological elements for the implementation of the WFD and was tested in Wallonia. For the period 2000–2002 involving 349 different sites, the element ‘benthic invertebrate fauna’ was in that way classified ‘high status’ for 31.5% of sites, ‘good status’ for 31.5% and below ‘good status’ for 37% of sites. The best ecological status (i.e., 100% ‘high’ and ‘good’ status) was found in river type ‘Arden’s xenotrophic brooks with strong slope’ and in river types 8large rivers with medium slope’. The worst status was found in river types ‘Loess brooks and rivers with medium slope’.     

河流生境的评估方法及应用的研究进展

河流生境是水生生物赖以生存的物理、化学和生物环境的综合体, 是河流生态系统的重要组成部分。河流生境评价有助于掌握河流的生态健康状况, 识别河流退化的原因, 为河流的生态修复提供依据。文章梳理总结了20世纪80年代至2018年文献中报道的全球范围内河流生境评估的方法, 然后根据每种方法的侧重点和目标, 将它们分为预测模型法和多指标综合评估法两种类型, 并比较了它们各自的优势和不足。预测模型法适于长期的生境动态监测, 但该方法需要以自然无干扰的河流为参照, 并且需要大量历史数据, 统一评估不易实现; 多指标综合评估法评估相对快速方便, 但评估过程复杂, 且评价标准不一, 结果有一定的局限性。这些方法的适用范围从中小型的可涉水河流到较大的不可涉水河流, 但适用于大型不可涉水河流的生境评估方法和案例非常有限。通过分类整理, 发现我国河流生境评估方法多是参考国外几种常用的河流评估方法, 种类单一, 而且多是针对个别河流, 并且未对这些河流所在的流域的生境状况进行深入研究, 广适性较差。因此, 文章从以下几个方面对我国河流生境评估体系的发展提出几点建议: (1)确定科学和标准化的评分指标, 因地制宜, 以满足不同河流特征; (2)扩大评估范围, 从流域和景观尺度开展生境监测, 关注全流域的健康状况; (3)扩大时间尺度, 建立模型, 进行长期的动态评估; (4)鼓励政府宏观规划, 促进不同管理部门间的合作, 整合不同地区的河流生境数据并建立国家尺度的河流生境大数据库, 以实现我国河流生态健康的维护和流域的可持续发展。     

Improvement of the ecological water qualification system of rivers based on the first results of the Hungarian phytobenthos surveillance monitoring

Results of an ecological quality ratio-based qualification system, developed on the basis of the analysis of 1,161 benthic diatom dataset of the Hungarian national database, are presented herein. Using Kohonen’s Self Organising Map technique, the 25 Hungarian physiographic river types were pooled into six larger distinct categories (diatom river groups). Diatom metrics were tested for their sensitivity to the targeted stressors (nutrients, COD hydromorphological alteration) in each group. The strongest relationships were found in the case of the IPS, SI and TI indices; therefore the average of these metrics (IPSITI) was proposed as a national multimetric index for Hungarian streams. Based on IPSITI values, the ratio of moderate to worse quality water was the highest in those groups containing small rivers. In the case of large, lowland and mid-altitude rivers with fine sediment, the good and moderate ecological status was more characteristic. Applicability of the IPSITI seems to be very useful in case of small- and medium-sized rivers. For these rivers, the index showed a significant relationship with nutrients and organic pollutants. In the case of very large rivers, the stressor–index relationships were not significant because of the insufficient number of samples and the small range of stressors.     

A healthy Fraser River? How will we know when we achieve this state?

Assessing the condition of an ecosystem to ascertain its health presupposes that we can diagnose pathological states in system measures. Frequently this means comparing current conditions to reference states, either historical or other sites, which also exhibit some natural range of variation. In the Fraser River, a 9th order river on the west coast of Canada, and one of the most productive salmon rivers in the world. we have studied assemblages of fish and benthos to assess ecosystem health. The biggest challenge to using species composition and abundance measures as indicators of system condition is the absence of appropriate reference conditions in many instances. There are few unperturbed rivers of large size in western North America, and indeed in much of the world, with which to compare the Fraser River or any other large river ecosystem. Multiple insults from point and non-point sources make it difficult to isolate factors from natural longitudinal changes in terms of their effects on river biota. Potential solutions include analysis of fragmentary historical data, making comparisons with other large rivers, and conducting extensive surveys within the basin to account for spatial gradients. An absolute diagnosis of ecosystem health of large rivers in natural science terms is unlikely, and otherwise will depend on relative changes through time assuming these can be isolated from natural variation and local effects. Definition of health for large, riverine ecosystems remains largely a case of expert opinion and weight of evidence rather than a testable hypothesis.     

Do intermittent and ephemeral Mediterranean rivers belong to the same river type?

The benthic macroinvertebrate communities and ecological quality of eleven temporary rivers (seven intermittent and four ephemeral) in Dadia National Park, north-eastern Greece, were examined with respect to the degree of flow temporality. Sampling took place during the high flow season at both ephemeral and intermittent sites and during the low flow season only at the intermittent ones, which receded to pools. Despite the remarkable seasonal variation in both the hydrology and ecology of the intermittent rivers, the various metrics and indices as well as the multivariate analyses confirmed the clear distinction between the two river types (ephemeral and intermittent). Existing European quality indices do not sufficiently differentiate between ephemeral and intermittent river types, and thus cannot reliably discriminate the degree of natural variability from human induced stressors in temporary rivers.     

Changes in the impact of anthropogenic effects on river water quality during the last 50 years in Japan

Japan’s rapid urbanisation over the last 50 years has resulted in land use and lifestyle changes, all of which are likely to have changed the quality of river water, and consequently the wetland and coastal environment. We examined changes in river water quality over this period by means of a review of previous studies. Around the 1950s, the weighted average of chloride using discharge of Japan’s 30 major rivers was 6.1 mg/l while in the 2000s it was 11.3 mg/l. Because there were no significant changes in the natural conditions, we have attributed the increase to the urbanisation of the last 50 years. Nitrate levels in the mountain streams of southern Japan have increased, particularly in the western part of the Kanto region. As this area is located on the leeward side of the Tokyo Metropolitan Area, depositions from aerosols are thought to be the main cause of the increased nitrate concentration. These two findings suggest that certain uses of land may affect river water quality differently over time, and that changes in land use may also affect river water quality in remote areas.     

What effect will a few degrees of climate change have on human heat balance? Implications for human activity

While many factors affecting human health that will alter with climate change are being discussed, there has been no discussion about how a warmer future will affect man’s thermoregulation. Using historical climate data for an Australian city and projections for Australia’s climate in 2070, we address the issue using heat balance modelling for humans engaged in various levels of activity from rest to manual labour. We first validate two heat balance models against empirical data and then use the models to predict the number of days at present and in 2070 that (1) sweating will be required to attain heat balance, (2) heat balance will not be possible and hyperthermia will develop, and (3) body temperature will increase by 2.5°C in less than 2 h, which we term “dangerous days”. The modelling is applied to people in an unacclimatised and an acclimatised state. The modelling shows that, for unacclimatised people, outdoor activity will not be possible on 33–45 days per year, compared to 4–6 days per year at present. For acclimatised people the situation is less dire but leisure activity like golf will be not be possible on 5–14 days per year compared to 1 day in 5 years at present, and manual labour will be dangerous to perform on 15–26 days per year compared to 1 day per year at present. It is obvious that climate change will have important consequences for leisure, economic activity, and health in Australia.     

Wicked Water: Engaging with Communities in Complex Conversations about Water Recycling

Water security is at the forefront of public attention in Australia. One response to Australia’s current water situation is water recycling; however, community responses to recycling have been contentious. Examining reactions to recycling reveals that debates are underpinned by competing discourses about water, giving rise to different ways of talking, writing, making meaning, and responding to issues of water security. In 2007 a local government in Australia considered a proposal to augment domestic water storages with highly treated wastewater. This was referred to as the “Water2WATER” project. A 3-month community consultation was conducted, including health and environmental assessments. Despite apparently favorable recommendations, the proposal was not considered suitable as an immediate response to securing the region’s water supply. The consultation revealed a host of competing environmental, scientific, and cultural discourses emerging from community, government, and industry responses. Introducing an ecosystem approach to engaging communities about water recycling may provide new ways of assisting communities come to terms with the challenges concerned with water security in the future.     

Changing otolith/fish size ratios during settlement in two tropical damselfishes

Otolith-fish size (O-L) relationships were analysed in recruits of two damselfish species (Chrysiptera rollandi and Pomacentrus amboinensis) before and after cohorts had settled onto reefs surrounding Lizard Island in Australia’s Great Barrier Reef. Unexpectedly, O was found to be unrelated to L in pre-settlers of both species. Settlers sampled only 12–15 days later, however, exhibited the expected isometric O-L relationship. This intriguingly rapid change—due to either variable growth, selective mortality or a combination of both—renders otolith increment widths inconsistent proxies for daily somatic growth rates in the pre- versus post-settlement stages of these pomacentrids.     

Lessons from practice: assessing early progress and success in river rehabilitation

This article comprises a literature analysis of 41 river rehabilitation projects to assess the short-term (5 years) ability of indicator groups to demonstrate progress towards river rehabilitation goals. Positive indications were compared to land-use, river size, rehabilitation intervention and time. A questionnaire was developed to investigate river manager’s interpretation of rehabilitation success and to assess their level of adherence to recommendations in the literature with regard to rehabilitation assessment on a conceptual level. A total of 54 responses were received from respondents based in Germany, The Netherlands and the United Kingdom. The results indicate that macroinvertebrate indicators, while widely used in assessing river rehabilitation efforts, exhibited a lower frequency of positive responses than most other indicator types in the short term. Conversely, terrestrial floodplain indicators exhibited the most frequent level of positive response for all ecological type indicators leading to recommendations for further investigations into their use for short-term monitoring. Assessment procedures recommended in literature are largely followed, illustrating the advances that have been made with regard to assessment planning. Indicator responses are influenced by scale factors, for example, land-use and river size, that are often not considered by rehabilitation managers. While an emphasis is placed on ecological, hydrological and morphological indicators in monitoring schemes, the socioeconomic perspective (emphasized in the literature as forming an integral part of the river system) is neglected.     

Bushfires,COVID-19 and Young People’s Climate Action in Australia

EcoHealth - Australia’s summer bushfires of 2020–2021 were catastrophic, negatively impacting people, and the natural environment. This climate change-related event exacerbated the...     

A Feasibility Study to Monitor the Macroinvertebrate Diversity of the River Nile Using Three Sampling Methods

The River Nile is one of the world’s major rivers. Its’ catchment in Egypt has a population of 75,000,000. River flow is highly regulated and there are known discharges of pollutants. 1035 km of the river downstream of the Aswan high dam was studied to test the hypothesis that representative qualitative samples can be used to estimate macroinvertebrate biodiversity. Benthic macroinvertebrates are difficult to sample in large rivers and a reliable sampling strategy is required to evaluate their ecological status. Three methods for sampling have been investigated. Ekman Grab, macrophyte sweep netting and Artificial Substrate Samplers (ASS) were used to sample 15 sites from Aswan to Cairo between September 2001 and June 2002. Organisms were identified to species level where possible. Taxon accretion curves indicated that the all taxa present at a site should be collected using either 15 grab samples, 10 macrophyte samples or 5 ASS. The best time to sample was May–June. The biodiversity of macroinvertebrates in the Nile was recorded as 50 taxa with values of 7–31 at individual bank-side sites. Mid-stream biodiversity was much lower (0–19). Lowest biodiversity occurred at sites with known pollution inputs whilst highest occurred at sites with high levels of sedimentation. A regular programme for biomonitoring is recommended which will allow current status to be confirmed and future changes detected.     

Subtle ‘boom and bust’ response of <Emphasis Type="Italic">Macquaria ambigua</Emphasis> to flooding in an Australian dryland river

The ecology of dryland rivers is driven by their highly variable hydrology, particularly flooding regimes, whereby intermittent floods typically generate ‘booms’ of primary and secondary productivity, including massive fish production. We tested these concepts in the Moonie River, Australia, using the percichthyid, Macquaria ambigua, a dryland river species known to display pronounced ‘boom and bust’ abundance patterns in response to floodplain inundation followed by extended periods of low to no channel flow. We expected that body condition (as measured by whole body lipid content) and biomass of M. ambigua would be related to prey biomass, and that these factors would all ‘spike’ following widespread flooding. Instead we found more subtle responses. There were ‘booms’ in biomass of Macrobrachium and zooplankton, two important food items, whereas M. ambigua maintained relatively low but sustained lipid and biomass levels following flooding. It appears that instead of a ‘boom’ in fish biomass, abundant invertebrate food resources and sustained lipid levels contributed to high survivorship of this species during the ‘bust’ period over cool dry months.     

Using diatom life-forms and ecological guilds to assess organic pollution and trophic level in rivers: a case study of rivers in south-eastern France

The European Union’s Water Framework Directive has set a target of achieving good ecological status for all aquatic environments in Europe by 2015. In order to determine the quality of aquatic environments, biological indicators such as diatoms are often used. However, biotic diatom indices can be difficult and time consuming to use because of complexity of species determination. We investigated whether the biological traits of diatoms in rivers (life-forms, size classes and ecological guilds) could be used to assess organic pollution and trophic level. We worked on a data set comprising 315 diatom species, determined at 328 river stations of south-east France and a variety of parameters. The abundances of some biological traits differed significantly between the different organic pollution and trophic levels, particularly stalked diatoms, and the motile and low-profile guilds.     

Are alien fish a reliable indicator of river health?

1. The ability of many introduced fish species to thrive in degraded aquatic habitats and their potential to impact on aquatic ecosystem structure and function suggest that introduced fish may represent both a symptom and a cause of decline in river health and the integrity of native aquatic communities. 2. The varying sensitivities of many commonly introduced fish species to degraded stream conditions, the mechanism and reason for their introduction and the differential susceptibility of local stream habitats to invasion because of the environmental and biological characteristics of the receiving water body, are all confounding factors that may obscure the interpretation of patterns of introduced fish species distribution and abundance and therefore their reliability as indicators of river health. 3. In the present study, we address the question of whether alien fish (i.e. those species introduced from other countries) are a reliable indicator of the health of streams and rivers in south‐eastern Queensland, Australia. We examine the relationships of alien fish species distributions and indices of abundance and biomass with the natural environmental features, the biotic characteristics of the local native fish assemblages and indicators of anthropogenic disturbance at a large number of sites subject to varying sources and intensities of human impact. 4. Alien fish species were found to be widespread and often abundant in south‐eastern Queensland rivers and streams, and the five species collected were considered to be relatively tolerant to river degradation, making them good candidate indicators of river health. Variation in alien species indices was unrelated to the size of the study sites, the sampling effort expended or natural environmental gradients. The biological resistance of the native fish fauna was not concluded to be an important factor mediating invasion success by alien species. Variation in alien fish indices was, however, strongly related to indicators of disturbance intensity describing local in‐stream habitat and riparian degradation, water quality and surrounding land use, particularly the amount of urban development in the catchment. 5. Potential confounding factors that may influence the likelihood of introduction and successful establishment of an alien species and the implications of these factors for river bioassessment are discussed. We conclude that the potentially strong impact that many alien fish species can have on the biological integrity of natural aquatic ecosystems, together with their potential to be used as an initial basis to find out other forms of human disturbance impacts, suggest that some alien species (particularly species from the family Poeciliidae) can represent a reliable ‘first cut’ indicator of river health.     

Assessing the range of newly established invasive species in rivers using probabilistic methods

Data on the presence of invasive species are often scarce, especially during the initial period following their introduction, when population abundance and species detectability are both still very low. In such cases, sporadic sightings in their newly occupied territory are often the only available information about their presence and distribution. Here, we demonstrate the potential of using probabilistic models for the assessment of the distribution of newly established invasive species in rivers, based on their sighting records. We have applied Solow’s equation to the sighting record of the Amur sleeper (Perccottus glenii) in the Danube River, to assess the probable range of its population. The method applied indicated that, at the time when the sightings have been made (2003–2008), the Amur sleeper population in the Danube most probably extended between the 704.5 and 1,178.5 river km, while it was highly improbable (P < 0.05) that it was present downstream from the 606 river km or upstream from the 1,277 river km. The application of this approach has, however, to be tested further on a larger number of scenarios and case studies in order to evaluate its reliability. What this method lacks in complexity, compared to more advanced species distribution assessments, it makes up by its ability to be easily used and quickly applied for preliminary assessments of the ranges of riverine species. As a result, the proposed approach might be of interest for scientists and managers dealing with invasive species.