Test procedures for measuring the (sub)chronic effects of chemicals on the freshwater cyclopoid Eucyclops serrulatus

Groundwater fauna downtown - Drivers, impacts and implications for subsurface ecosystems in urban areas

Groundwater fauna (stygofauna) comprises organisms that have adapted to the dark subterranean environment over a course of thousands and millions of years, typically having slow metabolisms and long life cycles. They are crucial players in the groundwater of oxygenic aquifers, and contribute to various ecosystem services. Today's knowledge of their sensitivity to anthropogenic impacts is incomplete and a critical analysis of the general relevance of local findings is lacking. In this review, we focus on those areas with the highest interference between humans and stygofauna: cities. Here is where local pollution by various contaminants and heat strongly stresses the unique groundwater ecosystems. It is demonstrated that it is difficult to discern the influence of individual factors from the findings reported in field studies, and to extrapolate laboratory results to field conditions. The effects of temperature increase and chemical pollution vary strongly between tested species and test conditions. In general, previous findings indicate that heating, especially in the long-term, will increase mortality, and less adapted species are at risk of vanishing from their habitats. The same may be true for salinity caused by road de-icing in cold urban areas. Furthermore, high sensitivities were shown for ammonium, which will probably be even more pronounced with rising temperatures resulting in altered biodiversity patterns. Toxicity of heavy metals, for a variety of invertebrates, increases with time and chronic exposure. Our current knowledge reveals diverse potential impacts on groundwater fauna by urban pollution, but our insights gained so far can only be validated by standardized and long-term test concepts.

Climate change scenarios of increased CO2 and temperature affect a coral reef peracarid (Crustacea) community

The effects of applying scenarios of increasing CO₂ and temperature, using a mesocosm experiment, on the structure of a macrofaunal coral reef peracarid community were investigated for the first time. Samples were taken from artificial substrate units (ASUs), colonized by macrofauna from the coral reef subtidal zone of Serrambi beach (Brazil). In the laboratory, the ASUs were exposed to a Control (Ctrl) treatment and three climate change Scenarios (Sc) (increase of T° of 0.6, 2, and 3 °C, and pH drop of 0.1, 0.3, and 0.7 units for Sc I, II and III respectively), and were collected after 15 and 29 days of exposure. Our results showed that the effect of different temperature and acidity levels under experimental climate change scenarios significantly impacted density, diversity and community structure. Major differences were observed when applying Sc II and III. Peracarida also showed a reduction in specimen number when comparing both exposure times. Overall, Amphipoda, Tanaidacea and Isopoda communities all displayed a reduction in the number of individuals for both scenarios and exposure time factors, while Cumacea responded negatively in all scenarios, suggesting that these individuals were more sensitive to the experimental conditions. Dissimilarities were greatest between the Ctrl and Sc III, particularly after 29 days. Two species, Elasmopus longipropodus (Amphipoda) and Chondrochelia dubia (Tanaidacea), greatly contributed to these dissimilarities. This study demonstrates that even an intermediate level of increasing ocean temperature and acidification will negatively impact the structure of the Peracarida macrofaunal community on coral reefs. Also demonstrates that different species of Peracarida exhibit divergent response patterns, highlighting the specific responses of these taxa to the impacts of environmental stressors. These outcomes highlight the importance of studying the effects of climate change on benthic peracarids, especially because they incubate their eggs. This characteristic can reduce migration potential and thereby reduces the individual's ability to disperse in response to a changing environment.

An Overview of Studies on Meiofaunal Traits of the Littoral Zone of Lakes

We carried out an overview of the studies on the traits of the meiofauna of the littoral zone of lakes to investigate the question relating to the Raunkiaeran shortfall (lack of knowledge on biological traits). For this purpose, we selected a series of keywords associated with response and effect traits (feeding habits, locomotion and substrate relation, body size, shape and mass, life history, reproductive strategy, respiration and thermal tolerance) and we counted the relative frequency of occurrence in a set of scientific papers retrieved from Web of Science. The results showed that, except for the traits related to diet and feeding habits, the Raunkiaeran shortfall is very pronounced for all meiofaunal taxa of the littoral zone of lakes, especially for those related to soft-bodied organisms. The reason behind this deficiency concerns many aspects ranging from the high taxonomic expertise required to the intrinsic difficulties of observing organisms of such a small size. The relationship with temperature has not been sufficiently explored and formalized in any of the examined traits; this research aspect needs to be rapidly addressed since the prospects of climate change impacts on lake littorals are expected to be particularly severe.

Environmental risk assessment of propranolol in the groundwater bodies of Europe

A growing concern for contamination due to pharmaceutical compounds in groundwater is expanding globally. The β-blocker propranolol is a β-adrenoceptors antagonist commonly detected in European groundwater bodies. The effect of propranolol on stygobiotic species (obligate groundwater dweller species) is compelling in the framework of environmental risk assessment (ERA) of groundwater ecosystems. In fact, in Europe, ERA procedures for pharmaceuticals in groundwater are based on data obtained with surrogate surface water species. The use of surrogates has aroused some concern in the scientific arena since the first ERA guideline for groundwater was issued. We performed an ecotoxicological and a behavioural experiment with the stygobiotic crustacean species Diacyclops belgicus (Copepopda) to estimate a realistic value of the Predicted No Effect Concentration (PNEC) of propranolol for groundwater ecosystems and we compared this value with the PNEC estimated based on EU ERA procedures. The results of this study showed that i) presently, propranolol does not pose a risk to groundwater bodies in Europe at the concentrations shown in this study and ii) the PNEC of propranolol estimated through the EU ERA procedures is very conservative and allows to adequately protect these delicate ecosystems and their dwelling fauna. The methodological approach and the results of this study represent a first contribution to the improvement of ERA of groundwater ecosystems.

Recommendations for ecotoxicity testing with stygobiotic species in the framework of groundwater environmental risk assessment

As a consequence of the growing global dependence on groundwater resources, environmental risk assessments (ERA) for groundwater are increasingly required and, with that, ecotoxicological studies with groundwater fauna (stygofauna). However, the literature on the ecotoxicological studies with stygobiotic species (i.e. species that complete their life cycle exclusively in groundwater) has not expanded significantly since the first paper published in this field. The limitations regarding the use of stygobiotic species for ecotoxicological testing are clear and consistent across the globe; stygobiotic species are often 1) naturally present in low numbers, 2) difficult to collect, and 3) difficult to culture under laboratory conditions. This paper reviews the methods used in ecotoxicological studies performed with stygobiotic species, and provides ten recommendations for Good Laboratory Practice (GLP) for such tests. The recommendations focused on the following 10 points: 1) the taxonomic identification, the life stage/size and gender of the test organisms; 2) collection methodology of the organisms, including collection location, conditions and methods; 3) holding and acclimation conditions in the laboratory; 4) exposure conditions such as test set up and exposure time, number of replicates and densities of organisms in tests and in test vessels; 5) range-finding test set up and schedule; 6) final test design, including details of controls and treatments, and replication options; 7) incubation conditions, specifying temperature, pH and oxygenation levels throughout the test; 8) test duration; 9) observations and endpoints; 10) test validity criteria and compliance. The recommendations were developed for the purpose of supporting future short-term ecotoxicological testing with stygofauna through providing consistency in the protocols. A discussion of the potential implications for groundwater managers and decision-makers committed to ERA for groundwater is included.

New light in the dark - a proposed multidisciplinary framework for studying functional ecology of groundwater fauna

Groundwaters provide the vast majority of unfrozen freshwater resources on the planet, but our knowledge of subsurface ecosystems is surprisingly limited. Stygofauna, or stygobionts -subterranean obligate aquatic animals - provide ecosystem services such as grazing biofilms and maintaining water quality, but we know little about how their ecosystems function. The cryptic nature of groundwaters, together with the high degree of local endemism and stygofaunal site-specific adaptations, represent major obstacles for the field. To overcome these challenges, and integrate biodiversity and ecosystem function, requires a holistic design drawing on classical ecology, taxonomy, molecular ecology and geochemistry. This study presents an approach based on the integration of existing concepts in groundwater ecology with three more novel scientific techniques: compound specific stable isotope analysis (CSIA) of amino acids, radiocarbon analysis (¹⁴C) and DNA analyses of environmental samples, stygofauna and gut contents. The combination of these techniques allows elucidation of aspects of ecosystem function that are often obscured in small invertebrates and cryptic systems. Carbon (δ¹³C) and nitrogen (δ¹⁵N) CSIA provides a linkage between biogeochemical patterns and ecological dynamics. It allows the identification of stygofaunal food web structures and energy flows based on the metabolic pathway of specific amino groups. Concurrently, ¹⁴C provides complementary data on the carbon recycling and incorporation within the stygobiotic trophic webs. Changes in groundwater environmental conditions (e.g. aquifer recharge), and subsequent community adaptations, can be pinpointed via the measurementof the radiocarbon fingerprint of water, sediment and specimens. DNA analyses are a rapidly expanding approach in ecology. eDNA is mainly employed as a biomonitoring tool, while metabarcoding of individuals and/or gut contents provides insight into diet regimes. In all cases, the application of the approaches in combination provides more powerful data than any one alone. By combining quantitative (CSIA and ¹⁴C) and qualitative (eDNA and DNA metabarcoding) approaches via Bayesian Mixing Models (BMM), linkages can be made between community composition, energy and nutrient sources in the system, and trophic function. This suggested multidisciplinary design will contribute to a more thorough comprehension of the biogeochemical and ecological patterns within these undervalued but essential ecosystems.

The role of freshwater copepods in the environmental risk assessment of caffeine and propranolol mixtures in the surface water bodies of Spain

In this study we aimed at assessing: (i) the environmental risk posed by mixtures of caffeine and propranolol to the freshwater ecosystems of Spain; (ii) the sensitivity of freshwater copepod species to the two compounds; (iii) if the toxicity of caffeine and propranolol to freshwater copepods contributes to the environmental risk posed by the two compounds in the freshwater bodies of Spain. The environmental risk was computed as the ratio of MECs (i.e. the measured environmental concentrations) to PNECs (i.e. the respective predicted no-effect concentrations). The effects of caffeine and propranolol on the freshwater cyclopoid Diacyclops crassicaudis crassicaudis were tested both individually and in binary mixtures. Propranolol posed an environmental risk in some but not in all the surface water ecosystems of Spain investigated in this study, while caffeine posed an environmental risk to all the investigated freshwater bodies, both as single compound and in the mixture with propranolol. Propranolol was the most toxic compound to D. crassicaudis crassicaudis, while caffeine was non-toxic to this species. The CA model predicted the toxicity of the propranolol and caffeine mixture for this species. D. crassicaudis crassicaudis was much less sensitive than several other aquatic species to both compounds. The sensitivity of D. crassicaudis crassicaudis does not increase the environmental risk posed by the two compounds in the freshwater bodies of Spain, however, further testing is recommended since the effect of toxicants on freshwater copepods can be more pronounced under multiple stressors and temperature increasing due to climate change.

Interactive effects of increased temperature, pCO2 and the synthetic progestin levonorgestrel on the fitness and breeding of the amphipod Gammarus locusta

Given the lack of knowledge regarding climate change-chemical exposure interactions, it is vital to evaluate how these two drivers jointly impact aquatic species. Thus, for the first time, we aimed at investigating the combined effects of increased temperature, pCO₂ and the synthetic progestin levonorgestrel on survival, growth, consumption rate and reproduction of the amphipod Gammarus locusta. For that, a full factorial design manipulating temperature [ambient temperature and warming (+4 °C)], pCO₂ [normocapnia and hypercapnia (Δ pH 0.5 units)] and the progestin levonorgestrel (LNG: L1 - 10 ngLL^-1 and L2 - 1000 ngLL^-1, control - no progestin and solvent control - vehicle ethanol (0.01%)) was implemented for 21 days. G. locusta was strongly negatively affected by warming, experiencing higher mortality rates (50-80%) than in any other treatments. Instead, growth rates were significantly affected by interactions of LNG with temperature and pCO₂. It was observed, in the short-term (7d) that under ambient temperature (18 °C) and hypercapnic conditions (pH 7.6), the LNG presence promoted the amphipod's growth, while in the medium-term (21d) this response was not observed. Relative consumption rates (RCRs), during the first week were higher than in the third week. Furthermore, in the first week, RCRs were negatively affected by higher temperature while in the third week, RCRs were negatively affected by acidification. Furthermore, it was observed a negative effect of higher temperature and acidification on G. locusta fecundity, contrarily to LNG. Concluding, the impact of increased temperature and pCO₂ was clearly more adverse for the species than exposure to the synthetic progestin, however, some interactions between the progestin and the climate factors were observed. Thus, in a future scenario of global change, the presence of LNG (and other progestins alike) may modulate to a certain level the effects of climate drivers (and vice-versa) on the gammarids fitness and reproduction.

Towards an integrated understanding of how micro scale processes shape groundwater ecosystem functions

Micro scale processes are expected to have a fundamental role in shaping groundwater ecosystems and yet they remain poorly understood and under-researched. In part, this is due to the fact that sampling is rarely carried out at the scale at which microorganisms, and their grazers and predators, function and thus we lack essential information. While set within a larger scale framework in terms of geochemical features, supply with energy and nutrients, and exchange intensity and dynamics, the micro scale adds variability, by providing heterogeneous zones at the micro scale which enable a wider range of redox reactions. Here we outline how understanding micro scale processes better may lead to improved appreciation of the range of ecosystems functions taking place at all scales. Such processes are relied upon in bioremediation and we demonstrate that ecosystem modelling as well as engineering measures have to take into account, and use, understanding at the micro scale. We discuss the importance of integrating faunal processes and computational appraisals in research, in order to continue to secure sustainable water resources from groundwater.