Microsporidia parasites are commonly found in amphipods, where they are often asymptomatic, vertically-transmitted and have several effects on host sexuality and behaviour. As amphipods are often used as models in ecotoxicological studies, we investigated the effect of microsporidian infections on energy reserves and defence capacities of Gammarus roeseli under cadmium stress. Only females were infected by two microsporidia parasites: Dictyocoela roeselum or Dictyocoela muelleri. In physiological conditions, microsporidia had no major effect on energy reserves and defence capacities of G. roeseli, while under cadmium exposure, energy reserves and antioxidant defence were weaker in infected females. Moreover, higher malondialdehyde levels detected in infected females revealed that they suffered more cellular damages. Our results suggest that microsporidia may affect gammarid fitness in stressful conditions, when parasitic stress cannot be compensated by the host. Consequently, microsporidia parasites should be a factor necessary to take into account in ecotoxicology studies involving amphipods.

The uptake and depuration of a range of pharmaceuticals in the freshwater shrimp (Gammarus pulex) and the water boatman (Notonecta glauca) was studied. For one compound, studies were also done using the freshwater snail Planobarius corneus. In G. pulex, bioconcentration factors (BCFs) ranged from 4.6 to 185,900 and increased in the order moclobemide < 5-fluoruracil < carbamazepine < diazepam < carvedilol < fluoxetine. In N. glauca BCFs ranged from 0.1 to 1.6 and increased in the order 5-fluorouracil < carbamazepine < moclobemide < diazepam < fluoxetine < carvedilol. For P. corneus, the BCF for carvedilol was 57.3. The differences in degree of uptake across the three organisms may be due to differences in mode of respiration, behaviour and the pH of the test system. BCFs of the pharmaceuticals for each organism were correlated to the pH-corrected liposome–water partition coefficient of the pharmaceuticals.

A comprehensive, weight-of-evidence based ecological risk assessment approach integrating laboratory and in situ bioaccumulation and toxicity testing, passive sampler devices, hydrological characterization tools, continuous water quality sensing, and multi-phase chemical analyses was evaluated. The test site used to demonstrate the approach was a shallow estuarine wetland where groundwater seepage and elevated organic and inorganic contaminants were of potential concern. Although groundwater was discharging into the surficial sediments, little to no chemical contamination was associated with the infiltrating groundwater. Results from bulk chemistry analysis, toxicity testing, and bioaccumulation, however, suggested possible PAH toxicity at one station, which might have been enhanced by UV photoactivation, explaining the differences between in situ and laboratory amphipod survival. Concurrently deployed PAH bioaccumulation on solid-phase micro-extraction fibers positively correlated (r² ≥ 0.977) with in situ PAH bioaccumulation in amphipods, attesting to their utility as biomimetics, and contributing to the overall improved linkage between exposure and effects demonstrated by this approach.

Neonicotinoid insecticides like thiacloprid enter agricultural surface waters, where they may affect predator–prey-interactions, which are of central importance for ecosystems as well as the functions these systems provide. The effects of field relevant thiacloprid concentrations on the leaf consumption of Gammarus fossarum (Amphipoda) were assessed over 96 h (n = 13–17) in conjunction with its predation on Baetis rhodani (Ephemeroptera) nymphs. The predation by Gammarus increased significantly at 0.50–1.00 μg/L. Simultaneously, its leaf consumption decreased with increasing thiacloprid concentration. As a consequence of the increased predation at 1.00 μg/L, gammarids' dry weight rose significantly by 15% compared to the control. At 4.00 μg/L, the reduced leaf consumption was not compensated by an increase in predation causing a significantly reduced dry weight of Gammarus (∼20%). These results may finally suggest that thiacloprid adversely affects trophic interactions, potentially translating into alterations in ecosystem functions, like leaf litter breakdown and aquatic-terrestrial subsidies.

The 1991 Gulf oil spill heavily impacted the coastal areas of the Saudi waters of the Arabian Gulf and recent studies have indicated that even 15years after the incident, macrobenthos had not completely recovered in the sheltered bays in the affected region such as, Manifa Bay. This study investigates the community conditions of macrobenthos in the open waters in one of the impacted areas, Al-Khafji waters, about 14years after the spill. Diversity measures and community structure analyses indicate a healthy status of polychaete communities. The BOPA index reveals that oil sensitive amphipods were recolonized in the study area. This confirms that the benthic communities of the oil spill impacted area had taken only <14 years to recover in the open waters of the impacted areas. The study also reveals the existence of three distinct polychaete communities along the depth and sediment gradients.

BACKGROUND, AIM AND SCOPE: There is growing evidence to show that dissolved humic substances, HSs, can directly interact with freshwater organisms, such as phototrophic organisms, cladocerans, amphipods and fish. The responses are—at least in part—transcriptionally controlled. These interactions can lead to stress symptoms in the exposed organisms. In phototrophs, stress symptoms include a reduction in photosynthetic oxygen release and antioxidative stress. Besides the direct effects, HSs also cause indirect effects that provoke different physiological adaptations in the phototrophs. MATERIALS AND METHODS: The HS-influenced photosynthetic performance and stress response of two different green algae, Pseudokirchneriella subcapitata (Koršikov) Hindák and Monoraphidium braunii (Nägeli in Kützing) Komárková-Legnerová, and two cyanobacterial species, Synechocystis sp. (PCC 6803, Institut Pasteur) and Microcystis aeruginosa (PCC 7806, Institut Pasteur), were tested. Two humic preparations were applied, the synthetic HS1500 and HuminFeed®, HF, which had previously been proven effective in bioassays with invertebrates and a water mould. RESULTS AND DISCUSSION: When the algae were grown near light saturation, most of the tested species were positively affected by HSs in growth rate or chlorophyll content. Cell sizes decreased with increasing HS concentrations for all eukaryotic phototrophs, except for the cyanobacteria. After 4 to 5 days of cultivation at the highest HS exposure, there was a decrease in total dry weight due to reduced cell sizes in contrast to an increase in cell numbers. With the exception of Synechocystis, the dry weight per cell ratio decreased with increasing HS concentration. The efficiency of utilizing absorbed light quanta increased with increasing HS concentrations; the maximum quantum yield of photosystem II (ΦPSIImax) was higher in all of the tested species, with the exception of M. aeruginosa, after exposure to HS. CONCLUSION: The applied humic preparations did not interact directly with PSII, but changed the physiological state of the algae, especially the photosynthetic performance. Neither the green algae nor the cyanobacteria were inhibited in growth or negatively affected in their photosynthetic performance. The exposure to lower concentrations of HS stimulated better growth of the phototrophs. The tested humic preparations obviously did not have the potency to act as xenobiotic stressors; furthermore, there was no sign of herbicide potency.