Breeding patterns of Arvicanthis neumanni in central Tanzania

The breeding pattern of the grass rat, Arvicanthis neumanni, was investigated in central Tanzania in 2002/2003 . Nine hundred and forty-seven animals were captured in three age groups: juveniles, sub adults and adults. These age groups were present in the population for an extended duration, but there was an increase in the number of sexually active individuals and juveniles 2–3 months after the onset of the rains (December 2002–May 2003). A peak in reproductive activity occurred between January and April. Litter size ranged between 5.58 ± 0.42 and 6.1 ± 0.26 in two study sites. There were no significant differences in the number of embryos implanted in the right and left horns of the uterus of pregnant females (t₂₂ = 0, P  > 0.05 and t₃₆ = 1.68, P  > 0.05, respectively). Sex ratio of A. neumanni was not skewed to either males or females. Breeding was seasonal and seemed to be associated with seasonal variations in primary productivity, which relates to rainfall patterns.     

A histological study on the development of the digestive system of Pseudosciaena crocea larvae and juveniles

The ontogenetic development of the gut and accessory organs in large yellow croaker Pseudosciaena crocea was investigated using light microscopy from hatching up to the juvenile stage (40 days post hatch, dph). At 3 dph (mean ±  s . d ., 4·1 ± 0·1 mm total length, L _T), coinciding with the buccopharynx opening, larvae started to feed exogenously, and the gut consisted of a well‐developed buccopharynx, a partially‐differentiated oesophagus and an intestine divided in three regions (anterior intestine, intermediate intestine and rectum). Yolk reserves were not completely depleted at the onset of exogenous feeding, and a period of mixed nutrition was observed up to 6 dph (4·3 ± 0·1 mm L _T), when yolk was definitively exhausted. Important morphological changes occurred at the end of the larval period, coinciding with metamorphosis. At 17 dph (6·8 ± 0·6 mm L _T), pyloric caeca differentiated at the junction of the pyloric stomach and the anterior intestine. Gastric glands were first observed at 21 dph (9·2 ± 1·2 mm L _T), coinciding with the morphological development of the stomach in three different regions (cardiac, fundic and pyloric) according to the histological characteristics of their mucosa. At this age, large longitudinal folds appeared in the median and posterior oesophageal mucosa. These morphological and histological features suggested the achievement of a digestive system characteristic of large yellow croaker juveniles and adults.     

Mortality of zebra mussel, Dreissena polymorpha, veligers during downstream transport

1. Streams flowing from lakes which contain zebra mussels, Dreissena polymorpha , provide apparently suitable habitats for mussel colonization and downstream range expansion, yet most such streams contain few adult mussels. We postulated that mussel veligers experience high mortality during dispersal via downstream transport. They tested this hypothesis in Christiana Creek, a lake-outlet stream in south-western Michigan, U.S.A., in which adult mussel density declined exponentially with distance downstream.
2. A staining technique using neutral red was developed and tested to distinguish quickly live and dead veligers. Live and dead veligers were distinguishable after an exposure of fresh samples to 13.3 mg L⁻⁻¹ of neutral red for 3 h.
3. Neutral red was used to determine the proportion of live veligers in samples taken longitudinally along Christiana Creek. The proportion of live veligers (mean ± SE) declined from 90 ± 3% at the lake outlet to 40 ± 8% 18 km downstream.
4. Veligers appear to be highly susceptible to damage by physical forces (e.g. shear), and therefore, mortality in turbulent streams could be an important mechanism limiting zebra mussel dispersal to downstream reaches. Predictions of zebra mussel spread and population growth should consider lake-stream linkages and high mortality in running waters.     

Optocardiographic recording of heart rate in Talitrus saltator (Amphipoda: Talitridae)

Abstract.  An optocardiographic non-invasive technique was used to monitor heart activity in small arthropods. Heart rate was recorded in adult individuals of the supralittoral amphipod Talitrus saltator after 3 h of immersion in marine artificial water (0, 11 and 33‰, t  = 15 ± 1 °C). Mean heart rate (± SE) ranged from 210 ± 26 beats min⁻¹ (at 33‰) to 276 ± 15 beats min⁻¹ (at 0‰) and, despite the small increase in temperature (0.5 °C) due to the infrared beam, the heart frequency remained constant for several hours. Neither the glue used to apply the sensor to the animal nor the beating of the pleopods affected heart rate. This technique could be a useful tool for the investigation of ecophysiological aspects in T. saltator , which is already well known for its ecology and behaviour.     

Comparison of the feeding habits of Eurasian otters on a fast flowing river and its backwater habitats

The diet and feeding habits of Eurasian otters Lutra lutra were studied by spraint analysis over a 2- year period, on three sections of the Drava River and three backwaters, in south-west Hungary. The primary food was fish (mean: 89.8% and 87.5% for riverine and backwater habitats, respectively); otters living in riverine habitats compared to backwaters, consumed more birds (3.9% and 0.7%, respectively), less mammals (0.5% and 0.9%, respectively), less reptiles and amphibians (5.6% and 10.2%, respectively) and less invertebrates (0.1% and 0.6%, respectively). In riverine habitats otters preyed more frequently on larger fish than in backwaters, but the main fish prey was small-sized (below 100 g in weight, 85.6% and 91.7%, respectively). On river sections they preyed more frequently on reophil (flow preferring fish, 18.9% and 3.3%, respectively), and less on stagnophil fish (stagnant waters preferring, 9.8% and 24.5%, respectively) than in backwaters. The main fish prey was eurytopic (tolerant of rivers and stagnant waters, 71.3% and 72.2%, respectively). Preference (by Ivlev's electivity index, E_i) in the Drava River for various fish guilds differed, as the otters preferred eurytopic (E_i= 0.30) and stagnophil fish (E_i= 0.24), and avoided reophil fish (E_i=−0.58). Otters did not threaten the rare, flow preferring fish species and the main diet consisted of economically unimportant species.     

Monitoring adult Eretmocerus mundus, Encarsia lutea and Bemisia tabaci with yellow sticky traps in cotton Gossypium hirsutum

Abstract:  The efficiency of yellow sticky traps for estimating adult population dynamics of Bemisia tabaci (Genn.) (Hom., Aleyrodidae) and its parasitoids Eretmocerus mundus Mercet, Encarsia lutea (Masi) (Hym., Aphelinidae) was examined in cotton in choice and no-choice studies in Çukurova, Turkey in 2004 and 2005. In the no-choice study, traps were suspended individually on the third, fifth or eighth main stem node branches from the tops of cotton plants. For the choice study, three traps were suspended on the same individual node branches on different plants. Trap captures were counted weekly. Mean (±SE) numbers of B. tabaci captured on traps were higher in no-choice (max.: 697.8 ± 55.6) compared with choice (max.: 533.3 ± 47.4) studies each year. Population fluctuation patterns of E. mundus and E. lutea adults were similar to those of adult B. tabaci on traps with low weekly mean numbers occurring initially and increasing to peak levels in mid-August, then decreasing in later weeks of the studies. The relationship between weekly mean numbers of B. tabaci and E. lutea was greater than the relationship between B. tabaci and E. mundus . Mean numbers of E. mundus and E. lutea on traps were higher at the third main stem nodes than traps suspended on the fifth or eighth node. Mean numbers of E. lutea pupae were usually higher than E. mundus from the first sampling date throughout the end of the growing season on leaves. The relationship between parasitoid pupae and adults captured in traps is discussed.     

Predatory effect of Orius niger (Wolff) (Hem., Anthocoridae) on Frankliniella occidentalis (Pergande) and Thrips tabaci Lindeman (Thysan., Thripidae)

The predatory effect of adult female Orius niger (Wolff) (Hem., Anthocoridae) on the larvae I–II and adults of two injurious thrips , Frankliniella occidentalis (Pergande) and Thrips tabaci Lindeman (Thysan., Thripidae), was examined in June 1997, in controlled environment chambers (temperature 22 ± 0.2°C, 65 ± 3% RH, a 16 h light : 8 h dark photoperiod and light intensity 9000 Lux). This study took place on sweet pepper leaves ( Capsicum annuum L.) in transparent small plastic cages at proportions of 1/5, 1/10, 1/20 and 1/30 predator/number of thrips for larvae I–II and adults separately for each thrips species. O. niger was proved an effective predator for the immature stages (larvae I–II) and for the adults of the two thrips species. We concluded that O. niger could be used with success for the biological control of thrips in greenhouses crops.     

Reproductive ecology of the river lamprey

The reproductive ecology of river lamprey Lampetra fluviatilis was investigated during the spawning period 2003 in the River Derwent, north‐east England. Over this period 1199 ± 104 individuals day⁻¹(mean ±  s . d .) were counted on one spawning site (area c . 450 m²), but mark‐recapture estimates suggested that >5000 river lamprey used this site over the same period and egg deposition was estimated as 168 000 eggs m⁻². The operational sex ratio of river lamprey in spawning clusters changed between spawning phases, from domination by females during the nest‐building phase (male : female ratio, 1 : 3·46), to a preponderance of males during the spawning phase (male : female, 1 : 0·37), followed by a return to a majority of females after spawning (male : female, 1 : 3·74). Recapture data showed that >97% of recaptured, tagged males were recorded at two or more nests, whereas almost 50% of recaptured, tagged females were recorded at the same nest, suggesting a promiscuous mating system, with a tendency towards polygyny within the population. Within the lower 80 km of the River Derwent and its tributaries, evidence of river lamprey spawning was found at only six sites, and most spawning (>80% of the observed spawning population) was at one site.     

Enhancing tourist opportunities to view spotted‐necked otters (Lutra maculicollis) at Rubondo Island National Park: can the apriori location of latrines simplify identifying best viewing areas?

We observed spotted‐necked otters (Lutra maculicollis) along a 5.17‐km section of shoreline at Rubondo Island National Park, Tanzania, during May 2008 and February, June–August 2009 to determine whether their activity areas were associated with latrine site (places along the shoreline where spotted‐necked otters scent mark by depositing scats and urine) as part of an assessment to determine how tourists or researchers can best view the species. For this assessment, we compared the distance of spotted‐necked otters sightings associated with the shoreline (n = 207) with the distance between an equal number of geographical information system (GIS)‐generated random points to the nearest latrine for each of the respective points. The mean distances for locations of spotted‐necked otter sightings to the nearest latrine differed from the mean distance of random points to latrines [171.9 m (SE = 11.30) and 66.1 m (SE = 8.16), respectively; t = ?9.23, df = 412, P < 0.001]. Sightings also were much (2.6 times) closer to latrines that occurred in groups than those that were isolated (single). Establishing viewing sites at or near latrines (particularly those occurring in clusters) would thus seem an effective way to maximize opportunities to see spotted‐necked otters.     

Does the foraging strategy of adult Short‐tailed Shearwaters cause obesity in their chicks?

The chick provisioning behaviour of Short-tailed Shearwaters Puffinus tenuirostris breeding at the northern edge of their distribution on Montague Island, New South Wales, was examined in February and March 1997. The duration of individual foraging trips of parents, weight changes of adults and chicks, and meal sizes delivered to chicks were determined. It was found that individual parents mixed a long foraging trip to Antarctic waters (14.4±2.0 days) with one to three short foraging trips (1.36±0.7 days, mode=1 day). Adults gained body mass on long trips and lost weight on short trips. The size of meals fed to the chicks was significantly greater after a long trip (161±21 g) than after a short trip (135±28 g), although short trips increased the overall chick feeding frequency. The variable number of short trips made by adult Short-tailed Shearwaters and the relationship between short trips and adult body condition were consistent with current life-history theory: adults do not sacrifice their own body condition to increase food delivered to their chicks.
Modelling revealed that this dual foraging strategy inevitable leads to chicks enduring long intervals between meals. These long intervals may have led to the evolution of an over-feeding strategy by parents and the nestling obesity reported in this shearwater. The durations of the long trips from Montague Island were significantly greater than those for Short-tailed Shearwaters breeding at the centre of their distribution in Tasmania, although there was no significant difference in the length of short trips. A commitment to feed regularly in Antarctic waters may explain why the breeding distribution of this species does not extend much further north.     

Qualitative detection of the NSAIDs diclofenac and ibuprofen in the hair of Eurasian otters (Lutra lutra) occupying UK waterways with GC�CMS

The pervasiveness of pharmaceuticals such as nonsteroidal anti-inflammatory drugs (NSAIDs) in the aquatic ecosystem through the discharge of wastewater, and their potential to biomagnify within this ecosystem, is now recognised. Residues of diclofenac and ibuprofen are currently being detected in surface waters and aquatic organisms throughout the UK and Europe. However, the levels of these residues in fish and other aquatic organisms, particularly lower trophic level prey species, have not yet been determined. While exposure to diclofenac is known to adversely affect fish, the degree to which other aquatic organisms are exposed and impacted through continuous ingestion of contaminated prey and interaction with the aquatic habitat remains unknown. The extent and effects of exposure to ibuprofen also remain largely unknown. As an exploratory subset of a broader study to investigate the detectability of diclofenac in alternative biological matrices, we analysed hair samples from Eurasian otters (Lutra lutra, n?=?28) for residues of the two NSAIDs using GC?CMS. The otters were collected from six counties in England as part of an ongoing otter health monitoring project at the Wildlife Veterinary Investigation Centre in Chacewater, UK. Diclofenac was qualitatively detected in five hair wash and 15 extract samples, and ibuprofen was determined to be present in at least two of the hair extract samples. Here, we provide preliminary evidence that otters are exposed to both NSAIDs and argue for further studies to identify residue loads in the otters and their prey to fully assess the pervasiveness of these compounds and potential risks of ongoing exposure to them.     

完达山东部欧亚水獭种群数量及出现频次影响因素

水獭作为淡水生态系统健康的指示种和旗舰物种,在维持水生生态系统平衡与稳定中发挥着重要作用。然而目前对于完达山东部地区水獭种群数量、分布及其生境选择的影响因素的研究较为匮乏,严重影响了对该物种的野外保护与管理工作。于2021年12月至2022年4月冬季河流封冻期,采用沿河随机样线调查和红外相机监测相结合的方法对完达山东部地区8条主河和23条支流内的欧亚水獭(Lutra lutra)种群数量、分布现状进行了调查,并利用广义可加模型探究水獭出现频次与环境因子的关系。研究结果表明:(1)欧亚水獭在完达山东部水獭种群数量为571-661只,水獭种群密度为沿河(0.5559±0.2898)只/km,呈现中间高,四周低的趋势;(2)环境因子对水獭出现频次影响分析表明,河流深度、距农田距离、距居民区距离和距道路距离是影响水獭出现频次的关键因素。水獭出现频次与河流深度(0-40 cm)呈线性正相关,当河流深度达到40-50 cm时,水獭出现频次最高,之后随着河流深度的增加,出现频次降低;水獭出现频次与距农田距离(0-1.5 km)呈非线性正相关,在距农田距离为1.5-2 km范围内,水獭出现频次最高,之后降低;水獭出现频次与距居民区距离呈线性正相关;水獭出现频次与距道路距离呈非线性关系,当距离>7 km时,二者之间呈现为正相关,反之呈现为负相关。因此,水獭选择栖息地偏向于河流深(40-50 cm),远离农田(1.5-2 km)、居民区和道路(>7 km)的水域。研究为完达山东部欧亚水獭物种保护提供了基础数据和理论依据,建议通过河岸土地覆盖类型的管理、在河岸周围建立森林缓冲区及加强水獭保护宣传力度等措施实现对水獭物种及其栖息地的维持和保护。     

Developmental stress in wild-living Drosophilids inferred from biometry: metric and meristic traits react differently to heterogeneous environmental conditions

Abstract.  1. During their development in natural conditions, Drosophila larvae and pupae face heterogeneous environmental conditions (HEC). Analysing the morphology of wild-living adults is a means of evaluating the effects of HEC.
2. Two drosophilid species of the Zaprionus genus that recently invaded the Nile delta were investigated, and three metric, size-related traits, and one meristic trait, the sternopleural bristle number, were measured. Data were compared with those of F₁ generation reared under favourable laboratory conditions.
3. Body size was smaller in nature, but also extremely variable among individuals, with an average coefficient of variation (CV) of 9.1 ± 0.3, against a much lesser value of 2.4 ± 0.1 in laboratory flies. Correlations among size traits were also greater in nature (0.96 ± 0.01) than in the laboratory (0.75 ± 0.04).
4. By contrast, sternopleural bristles produced similar results in wild-living and laboratory flies. In nature, mean numbers were only slightly less than in the laboratory and the CVs were almost identical (10.87 ± 0.70 vs 10.80 ± 0.76).
5. Fluctuating asymmetry of sternopleural bristles was also identical in the two kinds of flies, and was not influenced by HEC, indicating a high level of developmental canalisation with respect to HEC.
6. The implications of the results for the problems of field heritability and developmental stability are discussed.     

Nesting area fidelity and survival of female Common Goldeneyes Bucephala clangula: are they density‐dependent?

The breeding histories of 218 female Common Goldeneyes Bucephala clangula were recorded between 1971 and 2000 in a study area in Schleswig-Holstein, northern Germany. Females were first recorded breeding at a median age of 2 years usually in their area of hatching (philopatry). One hundred and two of 140 females (73%) re-nested only in one of the 13 nesting areas (clusters of nestboxes) for all their known life of up to 13 breeding seasons. The remaining 38 individuals moved between different nesting areas at least once between breeding attempts. The two oldest females were still breeding at a minimum age of 15 years (i.e. 13 years between first and last recorded breeding attempt). Temporal variations in annual survival rates of adult females could best be explained by a model with annual survival rate varying independently and randomly about a mean of 0.830 (se = ±0.023) with an estimated sd of ±0.092 (95% CI = 0.064, 0.138). No trend in the annual survival rate was detected over the study period of 30 years, although the presence of a moderate trend could not be ruled out. The absence of any discernible trend in survival at a time when the population size increased substantially indicates little, if any, density-dependence in survival of female Goldeneyes during this study.     

Early growth and juvenile population structure of lemon sharks Negaprion brevirostris in the Atol das Rocas Biological Reserve, off north‐east Brazil

Lemon sharks Negaprion brevirostris were sampled in the Atol das Rocas, a nursery area, on nine occasions from March 1999 to October 2003, during which 157 individuals were tagged and 35 were recaptured. The male : female sex ratio of captured individuals was 1 : 1·12. Mean ±  s . d . growth rates were 24·7 ± 3·4 cm year⁻¹ in total length ( L _T), 20·7 ± 3·2 cm year⁻¹ in fork length, and 19·5 ± 2·7 cm year⁻¹ in precaudal length. There was no significant difference in growth rates between males and females. Mean ±  s . d . increase in mass was 2565 ± 762 g year⁻¹. The von Bertalanffy growth parameters estimated by the Fabens method based on L _T were: k  = 0·077, L _∞ = 399·9 cm and t ₀ = −2·16. Despite the large variation of environmental conditions, particularly of tidal range and currents, and the lack of protective mangrove cover in the nursery area at Atol das Rocas, juvenile lemon sharks grew relatively faster than at other nurseries. Such rapid growth could be a response to abundant food availability or high risk of predation by adults that enter the nursery area.     

Population genetic structure of the tiger prawn (Penaeus monodon) in the coastal waters of South China, based on mitochondrial DNA control region sequences

Genetic variation and population structure of Penaeus monodon in the coastal waters of South China were detected using mitochondrial DNA control region sequences. Eighty individuals were collected at Sanya, Shenzhen, Zhanjiang and Beihai; 69 haplotypes with 157 polymorphic sites were detected. Nucleotide diversity (π) of the combined samples (6.16 ± 3.01%) was much higher than many other species in Chinese seas, such as Penaeus japonicus , Portunus trituberculatus , and Acanthopagrus schlegeli . Genetic differentiation was significant between Beihai and Sanya (pairwise F _ST = 0.09836, P < 0.05), and between Beihai and Shenzhen (pairwise F _ST = 0.12153, P < 0.05). Significant genetic differentiation among all populations was found by analysis of molecular variance ( amova ) ( F _ST = 0.053, P = 0.037 < 0.05). The upgma dendrogram of the four populations showed Sanya and Shenzhen as the closest to each other, with Beihai having the greatest genetic distance from Sanya and Shenzhen. The tiger prawn of the coastal waters of South China should therefore be bred as two separated stocks, avoiding inbreeding or outbreeding selection of P. monodon in the captive breeding program. According to our results one source population is Beihai, and the others are from Sanya and Shenzhen.     

Physiological impact of sea lice on swimming performance of Atlantic salmon

Atlantic salmon Salmo salar were infected with two levels of sea lice Lepeophtheirus salmonis (0·13 ± 0·02 and 0·02 ± 0·00 sea lice g⁻¹). Once sea lice became adults, the ventral aorta of each fish was fitted with a Doppler cuff to measure cardiac output ( ̇ ), heart rate ( f _H) and stroke volume ( V _S) during swimming. Critical swimming speeds ( U _crit) of fish with higher sea lice numbers [2·1 ± 0·1 BL (body lengths) s⁻¹] were significantly lower ( P  < 0·05) than fish with lower numbers (2·4 ± 0·1 BL s⁻¹) and controls (sham infected, 2·6 ± 0·1 BL s⁻¹). After swimming, chloride levels in fish with higher sea lice numbers (184·4 ± 11·3 mmol l⁻¹) increased significantly (54%) from levels at rest and were significantly higher than fish with fewer lice (142·0 ± 3·7 mmol l⁻¹) or control fish (159·5 ± 3·5 mmol l⁻¹). The f _H of fish with more lice was 9% slower than the other two groups at U _crit. This decrease resulted in ̇ not increasing from resting levels. Sublethal infection by sea lice compromised the overall fitness of Atlantic salmon. The level of sea lice infection used in the present study was lower than has previously been reported to be detrimental to wild Atlantic salmon.     

Interannual variation in pup production and the timing of breeding in benthic foraging Australian fur seals

Large interannual variations in reproductive success caused by fluctuations in oceanography and prey availability are common to many species of air breathing epipelagic predators. In contrast, little is known about variation in benthic foragers such as Australian fur seals ( Arctocephalus pusillus doriferus ). Between 1997 and 2007, pup production was assessed in 9 yr, while the timing of breeding and adult female condition was assessed in 5 yr at Kanowna Island in Bass Strait, southeastern Australia. Pup production was variable (     = 1,726 ± 42, range = 1,386–2,301), but without temporal trend, as was median birth date (     = 23 November ± 1, range = 21–25 November) and pupping synchrony (period of 90% births:     = 28 ± 2 d, range = 23–31 d). Pup production was negatively correlated with median birth date and positively correlated with female condition, winter sea-surface temperature (SST) and zonal wind strength within Bass Strait. Pup production was also negatively correlated with SST in the previous summer within Bass Strait and in the eastern Great Australian Bight upwelling region. The results suggest that the reproductive success of Australian fur seals is influenced by oceanography but less so than in otariids foraging epipelagically in major upwellings. Despite spanning several El Niño events, no correlation between pup production and the Southern Oscillation Index was observed.     

Acid phosphatase production by Aspergillus niger N402A in continuous flow culture

The production of acid phosphatases (E.C.3.1.3.2, ACPs) by Aspergillus niger N402A is regulated by specific growth rate, as well as phosphate availability and pH, as demonstrated by studies in continuous flow culture. Specific ACP activity was highest when A. niger was grown at pH 6.3 (64±8 U g⁻¹) or pH 2.8 (99±11 U g⁻¹), at a dilution rate of 0.07 h⁻¹ and phosphate concentrations below 0.46 mM. ACP production was growth correlated for specific growth rates between 0.07 and 0.13 h⁻¹. Four different ACPs, including two phytases, were produced by A. niger N402A. The ACP and the phytase with maximal activities at pH 5.5 were differentially expressed at different culture pH values, with greater production at low pH.     

Global climate change in large European rivers: long‐term effects on macroinvertebrate communities and potential local confounding factors

Aquatic species living in running waters are widely acknowledged to be vulnerable to climate‐induced, thermal and hydrological fluctuations. Climate changes can interact with other environmental changes to determine structural and functional attributes of communities. Although such complex interactions are most likely to occur in a multiple‐stressor context as frequently encountered in large rivers, they have received little attention in such ecosystems. In this study, we aimed at specifically addressing the issue of relative long‐term effects of global and local changes on benthic macroinvertebrate communities in multistressed large rivers. We assessed effects of hydroclimatic vs. water quality factors on invertebrate community structure and composition over 30 years (1979–2008) in the Middle Loire River, France. As observed in other large European rivers, water warming over the three decades (+0.9 °C between 1979–1988 and 1999–2008) and to a lesser extent discharge reduction (?80 m³ s^?1) were significantly involved in the disappearance or decrease in taxa typical from fast running, cold waters (e.g. Chloroperlidae and Potamanthidae). They explained also a major part of the appearance and increase of taxa typical from slow flowing or standing waters and warmer temperatures, including invasive species (e.g. Corbicula sp. and Atyaephyra desmarestii). However, this shift towards a generalist and pollution tolerant assemblage was partially confounded by local improvement in water quality (i.e. phosphate input reduction by about two thirds and eutrophication limitation by almost one half), explaining a significant part of the settlement of new pollution‐sensitive taxa (e.g. the caddisfly Brachycentridae and Philopotamidae families) during the last years of the study period. The regain in such taxa allowed maintaining a certain level of specialization in the invertebrate community despite climate change effects.