Nutrient enrichment is a significant cause of ecosystem change in coastal habitats worldwide. This study focuses on the change in a benthic macroinvertebrate community and environmental quality as assessed through different biotic indices following the construction of a sewage outfall pipe in the west of Scotland, from first implementation to seven years after operation of the pipe. Benthic macroinvertebrates are an important part of marine ecosystems because they mediate ecosystem processes and functions, are a key part of food webs and they provide many ecosystem services. Results indicated a clear change in benthic communities over time with an increase in species richness and changes to benthic community composition (specifically feeding type, bioturbation mode and ecological group) towards those indicative of organic enrichment. No clear spatial zonation was observed because organic carbon content increased over the entire area. According to a suite of benthic indices calculated, some negative changes were detectable following the start of sewage disposal, but largely negative community changes, and a change from ‘good’ to ‘moderate’ quality, only occurred seven years after implementation. The increase in species richness in response to increasing disturbance reduced the utility of a multi-metric index, the Infaunal Quality Index, which, instead of amplifying the signal of negative impact, dampened it. We suggest that any change in communities, regardless of direction, should be heeded, and species richness is a particularly sensitive and early warning indicator for this, but a suite of approaches is required to understand benthic community changes.

Cadmium, chromium, copper, nickel, lead and zinc concentrations in the bivalve mollusc Macoma balthica and the polychaete annelids Hediste diversicolor and Arenicola marina were measured, during winter and summer, at sites throughout the Severn Estuary and Bristol Channel. The mean concentration of each metal in A. marina was greater in the lower Severn Estuary than in the far less contaminated outer Bristol Channel and the concentration of a given metal, e.g. Cr, in a species occasionally peaked at a site, reflecting local metal contamination. The concentrations of each metal in each of these biomonitor species almost invariably differed significantly among sites and often seasons and there were sometimes interactions between site and season. This indicates that the various factors that determine the concentration of a metal in a species operate in a complex manner and that their individual effects can vary among sites and/or seasons. The rank order of each metal concentration in each species at a site within the estuary frequently did not match the sequence for the concentration of that metal measured in the sediment at that site at the same time. This lack of correspondence is likely to be due, at least in part, to one or both of the following: (1) variations in the bioavailability of certain metals among sites due to differences in such features as the metal-binding properties of the sediments; (2) the effects of the constant transport and redistribution of the sediments and thus also of their associated trace metals by the very strong tidal action that characterizes the Severn Estuary. This would mean that single time measurements do not accurately reflect the overall trace metal environment to which the biomonitor organism had been exposed in the weeks/months prior to sampling. Marked differences in the concentrations of certain metals, e.g. Cu and Zn, in co-occurring biomarker species could frequently be related to differences between the ability of these species to regulate certain metals. Non-metric multi-dimensional scaling ordination and associated tests emphasize that the relationships between the concentrations of the various metals differed markedly among species and between sites and seasons in individual species and elucidated which metals contributed most to those differences. If the proposed scheme for harnessing tidal power in the Severn Estuary proceeds, the data in this paper provide a baseline for assessing the impact of such major changes on the bioavailability of trace metals in this estuary. This information will also be invaluable for predicting the changes likely to occur in other estuaries that become subjected to major structural changes.

Vineyards are a dominant feature of many landscapes in Mediterranean-climate regions. We examined the effects of streamflow declines, associated with vineyard water-withdrawals for frost protection, on benthic-macroinvertebrate communities at three sites along three small streams in the Mediterranean-climate region of Northern California. One site was heavily affected by water withdrawals for frost protection, the other two were not. In addition, we examined relationships between vineyard coverage and benthic-macroinvertebrate community response using data from 59 sampling events at 39 sites along 35 small streams in Napa County, California. We tested three a priori hypotheses in terms of the response of biological traits of benthic macroinvertebrates to high vineyard coverage: (1) proportion of individuals with semi-voltine (i.e., one generation every 2 years) life cycles would be lower compared to those with uni- and multi-voltine cycles, (2) proportion of individuals able to undergo diapause would be higher, and (3) proportion of individuals with the ability to burrow into the substrate would be higher. In the three-site study, we found that vineyard water-withdrawals for frost protection coincided with consistently lower values in both the benthic-macroinvertebrate index of biotic integrity (B-IBI) developed for Northern California streams and the ratio of Ephemeroptera–Plecoptera–Trichoptera to Odonata–Coleoptera–Hemiptera individuals (EPT/OCH), a metric developed for European Mediterranean streams. In the broader-scale study, we observed that vineyard-coverage levels above about 20% coincided with lower values of the B-IBI. The semi-voltine life-cycle trait was lower above this level, whereas the diapause and burrowing traits were not affected.

Anthropogenic land use within watersheds has substantial effects on aquatic habitats and biological communities. From September 2006 to December 2008, we investigated the effects of land use on benthic macroinvertebrate communities by comparing Song Stream and Odae Stream, two adjacent mountain streams in Korea whose watersheds have different land use patterns. Song Stream is significantly disturbed by agricultural activities in the watershed, whereas Odae Stream is relatively undisturbed and is surrounded by a well-conserved forest area. Song Stream had significantly higher levels of all nutrients and sediment-related factors due to the adjacent agricultural area. As a result, Song Stream had markedly lower species community indices, such as taxa richness and abundance. In Song Stream, macroinvertebrate scrapers and predators were most adversely affected, whereas collector-gatherers became a dominant group. Based on correlation and multivariate analyses, total dissolved solids had the strongest negative relationship with macroinvertebrate assemblages, followed by electrical conductivity, total nitrogen, and pH. The proportion of cobble in stream substrate was positively related to the richness and abundance of macroinvertebrates. Our results indicate that disturbances caused by agricultural land use, particularly sand deposition, had significant adverse effects on macroinvertebrate habitats and on the biotic integrity of benthic macroinvertebrate communities.

Benthic macroinvertebrates collected at seven different streams displaying different pollution levels were used to investigatespecies abundance patterns in polluted streams. Community response to disturbances in streams was analysed using speciesabundance distribution (SAD) for benthic macroinvertebrates across different levels of pollution. The slopes of rank abundancewere characteristically steeper with decreasing species richness at the polluted sample sites, while the slopes were less steep withhigher species richness at the clean or slightly disturbed sample sites. The SADs were broadly fitted to the log normaldistribution in benthic macroinvertebrate communities across different levels of pollution. A geometric series was partly acceptedfor the communities at the severely polluted sites where new species could not be readily introduced. A power law was applied tothe SADs, and the parameters reflected the states pertaining to the sample sites. The SADs were also efficient in revealingecological state of communities where physico-chemical indicators could not be easily differentiated for stressful conditions instreams.

We investigated the abundance, diversity and community structure of mayflies (Ephemeroptera), stoneflies (Plecoptera) andblackflies (Diptera : Simuliidae) in the Sébaou basin (Algeria). Fifty-five species were collected (i.e. 22 mayflies, 14 stonefliesand 19 blackflies species) in 18 sampling sites located in both main streams and tributaries of the Sébaou river (Great Kabylie,North Algeria). Analysis of species diversity of the three considered taxa showed an altitudinal gradient with maximal diversityin the piedmont and low altitude mountain areas (from 200 to 500 m), which provided the most heterogeneous habitats to thebenthic fauna. In contrast, the low diversity of the lowland sites was due to high water temperatures, reduced summer dischargeand anthropogenic disturbances. In the same way, the low diversity of the high mountain areas can be attributed either to lowwater temperatures or high fluctuation in daily temperature. Three species assemblage groups are revealed, the first two are relatedto an upstream-downstream gradient, with headwater sites characterised by stoneflies species and middle stream sites by ahigh mayfly and blackfy diversity and abundance. The third group was identified as spring sites characterised by a low abundanceand occurrence of stonefly species.Both altitudinal species diversity gradient and species assemblage of the Sébaou wadi were different from European and temperateareas, revealing that the accentuated North African Mediterranean climate could induce changes to both species and communitystructure. These results provide insights to the influence of some environmental features on aquatic insect species distributionand community structure in North African streams.

La faune d'un hydrosystème intègre la variabilité spatio-temporelle de l'environnement. Les espèces présentant les caractéristiques biologiques et les stratégies écologiques les plus appropriées à chaque type d'habitat de la mosaïque fluviale sont supposées sélectionnées. Certaines combinaisons d'adaptations sont donc susceptibles d'être plus particulièrement rencontrées dans certains habitats, compte-tenu de leurs caractéristiques environnementales. Par conséquent, une utilisation pertinente des informations autécologiques connues sur les différentes unités systématiques d'un peuplement, doit permettre la restitution et le suivi de certaines des caractéristiques environnementales d'un biotope à travers l'évolution qualitative et quantitative de son peuplement faunistique. Les mésohabitats les plus représentatifs de douze stations situées sur des cours d'eau d'ordre 1 à 4 appartenant à trois bassins versants du Nord-Est de la France et couvrant un large éventail de situations mésologiques ont été échantillonnés au filet-Surber au printemps et à l'automne 1993 et 1994. Les caractéristiques biologiques et les stratégies écologiques des organismes aquatiques rencontrés sont décrites par 13 variables s'exprimant selon différentes modalités. La confrontation des connaissances acquises sur l'autoécologie des taxons et de la dynamique spatio-temporelle du peuplement autochtone génère une information claire sur l'organisation et le fonctionnement de la communauté benthique, les caractéristiques de l'environnement et sur leurs modifications éventuelles, à différentes échelles spatiales (mésohabitat, station, bassin...). A chaque type de mésohabitat correspond une communauté benthique qui présente une combinaison originale de traits biologiques et de stratégies écologiques. Les taxons de cette communauté peuvent alors restituer une information pertinente sur les propriétés des mésohabitats qu'ils colonisent, que ce soit en terme de stabilité, de diversité et/ou de potentialités trophiques des niches écologiques proposées.

Les résultats d'une étude du peuplement des macroinvertébrés benthiques dans le réseau hydrographique de la rivièreSimeto sont exposés. La recherche a été menée sur 8 stations du cours principal et sur une station de chacun des affluents :T. Saracena, T. Cutò, R. Troina, R. Salso. Les échantillonnages ont été effectués mensuellement d'octobre 1988 à novembre1989. L'analyse a mis en évidence la présence d'une richesse faunistique considérable (267 taxa) représentée surtout parles Hydracariens, Ephéméroptères, Odonates, Plécoptères, Coléoptères, Trichoptères et Diptères. Cette richesse est maximaledans la partie haute du bassin, tandis que dans la partie inférieure le nombre de taxons de chaque groupe diminueconsidérablement. Cet appauvrissement est attribué aux impacts directs ou indirects des différentes activités humaines.