Invertebrate traits, diversity and the vulnerability of groundwater ecosystems

Funding Information: This manuscript evolved from a workshop titled Trait‐based analyses in groundwater ecology and bioassessment held as part of the 24th International Conference on Subterranean Biology, 20–24th August 2018, University of Aveiro, Portugal. The workshop was supported by the conference organisers and the Macquarie University Species Spectrum Research Centre. Financial support was also provided to M.A.D. by the Portuguese government (Fundação para a Ciência e Tecnologia; FCT) through the research unit UIDB/04085/2020 (CENSE). A.S.P.S.R. was supported by the VILLUM FONDEN (research grant 15471) and by Portuguese National Funds through Fundação para a Ciência e a Tecnologia within the cE3c Unit funding UIDB/00329/2020. S.I.S. acknowledges funding through EU Operational Programme Research, Development and Education No. CZ.02.2.69/0.0/0.0/16_027/0008357, and by the Ministry of Education, Youth and Sports of the Czech Republic [grant number CZ.02.1.01/0.0/0.0/16 025/0007417]. K.L.K. was supported in part by Australian Research Council grant LP190100927. The comments of the Editor, Associate Editor and an anonymous reviewer greatly improved the MS. Open access publishing facilitated by Macquarie University, as part of the Wiley ‐ Macquarie University agreement via the Council of Australian University Librarians. Publisher Copyright: © 2022 The Authors. Functional Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.Groundwater comprises the largest freshwater ecosystem on the planet. It has a distinct regime of extreme, yet stable environmental conditions that have favoured the development of similar morphological and functional traits in the resident invertebrate fauna (stygofauna). The analysis of community traits is increasingly used as an alternative to taxonomy-based assessments of biodiversity, especially for monitoring ecosystem status and linking the functions of organisms to ecological processes, yet it has been rarely applied to stygofauna and groundwater ecosystems. In this paper, we review the variation in functional traits among the invertebrate fauna of this important ecosystem. We focus on the stygofauna and processes of alluvium and fractured rock aquifers that are typified by small voids and fissures that constrain the habitats and environmental conditions. As a first step, we compare trait variability between groundwater and surface water invertebrate communities and then examine the significance of the ranges of these traits to the vulnerability of the ecosystem to change. Fifteen potentially useful functional traits are recognised. Eight of these have narrower ranges (i.e. exhibit fewer states, or attributes, of a particular trait) in groundwater than they do in surface water. Two traits have wider ranges. Our synthesis suggests that the relative stability of groundwater environments has led to low trait variability. The low biomass and low reproductive rate of stygofauna suggest that recovery potential following disturbance is likely to be low. For the purposes of both improved understanding and effective management, further work is needed to document additional functional traits and their states in groundwater fauna, enabling a better understanding of the relationship between response and effect traits in these ecosystems. Read the free Plain Language Summary for this article on the Journal blog.publishersversionpublishe

Hydrogeochemical changes before and during the 2016 Amatrice-Norcia seismic sequence (central Italy)

Seismic precursors are an as yet unattained frontier in earthquake studies. With the aim of making a step towards this frontier, we present a hydrogeochemical dataset associated with the 2016 Amatrice- Norcia seismic sequence (central Apennines, Italy), developed from August 24th, with an Mw 6.0 event, and culminating on October 30th, with an Mw 6.5 mainshock. The seismic sequence occurred during a seasonal depletion of hydrostructures, and the four strongest earthquakes (Mw ≥ 5.5) generated an abrupt uplift of the water level, recorded up to 100 km away from the mainshock area. Monitoring a set of selected springs in the central Apennines, a few hydrogeochemical anomalies were observed months before the onset of the seismic swarm, including a variation of pH values and an increase of As, V, and Fe concentrations. Cr concentrations increased immediately after the onset of the seismic sequence. On November 2016, these elements recovered to their usual low concentrations. We interpret these geochemical anomalies as reliable seismic precursors for a dilational tectonic setting

Earthquakes trigger the loss of groundwater biodiversity

Earthquakes are among the most destructive natural events. The 6 April 2009, 6.3-Mw earthquake in L\u27Aquila (Italy) markedly altered the karstic Gran Sasso Aquifer (GSA) hydrogeology and geochemistry. The GSA groundwater invertebrate community is mainly comprised of small-bodied, colourless, blind microcrustaceans. We compared abiotic and biotic data from two pre-earthquake and one post-earthquake complete but non-contiguous hydrological years to investigate the effects of the 2009 earthquake on the dominant copepod component of the obligate groundwater fauna. Our results suggest that the massive earthquake-induced aquifer strain biotriggered a flushing of groundwater fauna, with a dramatic decrease in subterranean species abundance. Population turnover rates appeared to have crashed, no longer replenishing the long-standing communities from aquifer fractures, and the aquifer became almost totally deprived of animal life. Groundwater communities are notorious for their low resilience. Therefore, any major disturbance that negatively impacts survival or reproduction may lead to local extinction of species, most of them being the only survivors of phylogenetic lineages extinct at the Earth surface. Given the ecological key role played by the subterranean fauna as decomposers of organic matter and "ecosystem engineers", we urge more detailed, long-term studies on the effect of major disturbances to groundwater ecosystems

Impacts of Veterinary and Human Medicinal Products in Groundwater Ecosystems

Tese de mestrado, Biologia Humana e Ambiente, 2022, Universidade de Lisboa, Faculdade de CiênciasOs ecossistemas subterrâneos são uma importante fonte de água potável, da qual a maioria da população mundial depende. Os aquíferos são explorados para atividades como a agricultura e indústria, além dos usos domésticos, sofrendo enormes pressões pelas quantidades extraídas, e pela poluição que os atinge. Entre estes poluentes encontram-se os fármacos, administrados em humanos e animais, que os irão metabolizar e excretar através das fezes e urinas. Assim, as águas subterrâneas recebem compostos originais e metabolitos resultantes do metabolismo destes fármacos, sendo que ambas as formas poderão impactar o equilíbrio dos ecossistemas subterrâneos. Os efluentes domésticos e hospitalares são uma importante fonte de poluição, assim como a agricultura, que utiliza com frequência estrume contaminado com estes fármacos. Tudo isto atinge as águas subterrâneas por percolação e infiltração. O ecossistema subterrâneo é caracterizado pela completa escuridão, elevada humidade e temperatura estável. Este ecossistema possui ainda cadeias tróficas truncadas, característica que leva a que exista pouca redundância nas funções desempenhadas por cada organismo. Devido à escuridão que caracteriza este ecossistema, existe ainda ausência de produção primária de origem fotossintética, sendo que quando existe produção primária, esta é de origem quimiolitotrófica. Estes ecossistemas possuem assim uma dependência dos compostos orgânicos externos que surgem das escorrências e da ação da gravidade. Adicionalmente, os organismos que habitam estes ecossistemas possuem eles próprios características adaptativas similares, tais como a despigmentação, o metabolismo lento, a ausência de visão, o alongamento dos apêndices, elevada longevidade, e a produção de menos ovos, ainda que maiores. Estas espécies possuem um elevado grau de endemismo, pelo que se encontram mais suscetíveis a eventos catastróficos. Estes ecossistemas subterrâneos tão enigmáticos quanto desconhecidos, fornecem serviços de ecossistemas fundamentais. Para além de consistirem uma importante reserva de água potável, estes ecossistemas procedem à purificação de água e à manutenção do ciclo de nutrientes, possível devido aos animais que nestes ecossistemas habitam e que se alimentam de biofilmes e bactérias. Estes ecossistemas fornecem ainda refúgio a várias espécies, e são importantes locais espirituais e turísticos. De momento, as indicações pela Agência Europeia do Medicamento sugerem a realização de testes ecotoxicológicos em organismos de superfície, como substitutos aos organismos subterrâneos, os troglóbios (terrestres) ou estigóbios (aquáticos). Na avaliação de risco ambiental são considerados os três níveis tróficos: produtores primários, consumidor primário e consumidor secundário. Ainda que nos ecossistemas aquáticos de superfície o nível trófico dos produtores primários (fotossintéticos) pode ser considerado bem representado, tal não acontece no ecossistema subterrâneo. Na determinação do quociente de risco ambiental de um certo fármaco para o ecossistema subterrâneo, é necessário a utilização de dois fatores de avaliação: para a obtenção do valor mínimo em que o organismo subterrâneo é afetado é necessária a divisão do valor mínimo em que o organismo de superfície é afetado por 10; para a obtenção da concentração existente nos aquíferos é necessária a multiplicação por 0,25 ao valor encontrado nas águas superficiais. A divisão pelo fator de avaliação de 10 tem o objetivo de proteger os organismos subterrâneos, considerados mais vulneráveis, enquanto a multiplicação pelo fator de 0,25 tem o intuito de considerar a percolação e infiltração nos solos, que poderão diminuir a concentração de fármacos ao longo do percurso até aos aquíferos. Ainda assim, as diferenças fisiológicas e metabólicas existentes entre os organismos de superfície e os organismos estigóbios levantam dúvidas sobre a adequação das indicações atuais da Agência Europeia do Medicamento para a proteção dos ecossistemas subterrâneos. O objetivo principal desta dissertação é aumentar o conhecimento científico na área da avaliação de risco e gestão ambiental, através do estudo do impacto dos fármacos diclofenaco de sódio e acetaminofeno no estigóbio Proasellus lusitanicus, uma espécie aquática cavernícola endémica do centro de Portugal. O estudo da mortalidade do P. lusitanicus após exposição a diclofenaco de sódio, um anti-inflamatório não-esteróide frequentemente encontrado nas águas subterrâneas, foi efetuado através de. um teste ecotoxicológico que. consistiu num teste sem limite temporal, sendo o término determinado pela estabilidade do fármaco ou pela observação da cessação da mortalidade. Esta abordagem foi complementada com a exploração de quatro cenários para o cálculo do quociente de risco para o fármaco diclofenaco de sódio. O cálculo do quociente de risco consiste na divisão da concentração do fármaco quantificada numa massa de água pela concentração em que se prevê não haver efeito no organismo. Assim, no cenário 1 e 3, a concentração medida nas massas de água foi estimada através da análise de literatura, enquanto no cenário 2 e 4 foi estimada com recurso a uma base de dados, disponibilizada pela Agência Europeia do Ambiente. A concentração em que não se prevê qualquer efeito no organismo foi estimada no cenário 1 e 2 através das indicações da Agência Europeia do Medicamento, e no cenário 3 e 4 através do teste ecotoxicológico realizado com estigóbios da espécie P. lusitanicus. Os resultados indicam que P. lusitanicus possui uma tolerância inicial elevada ao fármaco diclofenaco de sódio. No entanto, esta tolerância vai diminuindo à medida que o período de exposição aumenta. Entre os quatro cenários calculados, aquele que apresenta um quociente de risco maior foi o cenário calculado consoante as indicações da Agência Europeia dos Medicamento. Este resultado sugere que as indicações atuais são adequadas para a proteção dos ecossistemas subterrâneos. Esta dissertação estudou também os efeitos subletais do fármaco acetaminofeno, um fármaco usado com frequência, e um contaminante recorrente das águas subterrâneas. Os efeitos subletais foram estudados através da quantificação de biomarcadores relacionados com a defesa, o stress oxidativo, a neurotoxicidade, e a produção de energia, após uma exposição de 14 dias a acetaminofeno. Após a exposição, foram analisados os níveis ou atividade dos biomarcadores glutationa total, glutationa Stransferase, peroxidase lipídica, sistema de transporte de eletrões, colinesterase e proteína total. O estudo dos níveis ou atividades de biomarcadores de dano e de defesa após exposição a acetaminofeno, quantificados nesta espécie pela primeira vez, indicam que este estigóbios possui um mecanismo de destoxificação adequado, visível pelas diferenças existentes na glutationa total e na glutationa Stransferase. Este mecanismo de destoxificação permitiu evitar dano celular em concentrações sub-letais, visível pela ausência de diferenças na peroxidase lipídica, no sistema de transporte de eletrões, e na colinesterase. Até ao momento, as indicações existentes para a proteção do ecossistema cavernícola parecem ser adequadas para o efeito, sendo necessário ter em conta que os estigóbios utilizados nestes estudos são adultos, e que indivíduos mais juvenis poderão ser mais sensíveis a estes fármacos. Adicionalmente, é necessário ter em atenção que estes estudos foram realizados para concentrações de apenas um fármaco, e não para a mistura de vários em simultâneo, como tantas vezes ocorre nas águas subterrâneas. Estes estudos não permitem tirar conclusões sobre o efeito destes fármacos na fertilidade desta espécie, um fator que pode interferir nos números de uma população, nem concluir sobre o efeito conjunto do aumento da temperatura e da exposição a fármacos na sobrevivência e mortalidades destes indivíduos. Esta dissertação representa o primeiro esforço no sentido de compreender o efeito pernicioso dos fármacos em organismos de águas subterrâneas em Portugal, testando os seus efeitos em espécies endémicas. Estudos futuros são fundamentais para tentar preencher estas e outras lacunas existentes, que levarão à produção de indicações mais adequadas para a proteção dos enigmáticos ecossistemas subterrâneos tantas vezes esquecido, ainda que tão importante.Groundwater is an important source of fresh water, with the majority of world population depending on it. This resource sustains activities such as agriculture, industry, and domestic use, and suffers pressures from the high amount of water extracted, agriculture pollution, industry and domestic effluents, and hospital sewages, through percolation and leachate. This ecosystem is characterized by darkness, high humidity, and stable temperature, with truncated trophic chains and no primary photosynthetic production. This ecosystem is inhabited by organisms with unique traits, such as depigmentation, slow metabolism, and blindness, among others. Furthermore, groundwater ecosystems provide important ecosystem services, such as water purification, nutrient cycling, and cultural services. Currently, guidelines suggest using surface species as a proxy for groundwater organisms, the so-called stygobitic species, after using an assessing factor of 10 to account for the vulnerability of these species. This dissertation aims to increase the scientific knowledge in groundwater environmental risk assessing and management, by studying the mortality of diclofenac sodium and sublethal effects of acetaminophen in stygobitic species Proasellus lusitanicus. Besides studying mortality, by using a Time-Independent assay, this dissertation focused on sublethal effects as well, by quantifying levels and activity of defence and stress biomarkers. This species shows a remarkable tolerance to diclofenac sodium, which decreases over time of exposure. Furthermore, the current guidelines for groundwater ecosystem’s protection are adequate. By studying defence and stress biomarkers after a 14-day exposure of acetaminophen, it was show that this species has a successful detoxification mechanism. This helps to explain this species’ tolerance to diclofenac sodium. In the future, more studies are necessary to better understand the impacts of these groundwater pollutants

Assessing spatial and temporal changes in diversity of copepod crustaceans. A key step for biodiversity conservation in groundwater-fed springs

Despite the close attention springs have received from a hydrologic perspective and as biodiversity hotspots, the multiple dimensions of spring meiofaunal assemblage diversity are still poorly investigated. Knowledge of beta diversity patterns and drivers can inform and improve management decisions on biodiversity conservation. Here, we analyzed beta diversity of copepod assemblages in karst springs in Central Italy by focusing on: 1) relative contributions of turnover and nestedness components to taxonomic and phylogenetic beta diversity; 2) temporal variation of species richness and beta diversity within and between the target springs in conjunction with models of the influence of physical-chemical parameters on within-spring diversity changes; 3) expected risk of habitat loss due to variation in groundwater recharge under climate change. To this end, we gathered data from 168 samples collected in four karst springs from 2004 to 2016. Overall, we found 48 copepod species, 22 of which are obligate groundwater dwellers while the remaining 26 usually occur in surface freshwaters. All springs showed significant changes in taxonomic and phylogenetic beta diversity over time. Total beta diversity was high for both the taxonomic and phylogenetic dimensions, and turnover was the main component. Inter-site variability in dissolved oxygen explained a noticeable part of temporal variation in beta diversity, likely reflecting the role of microhabitat heterogeneity in shaping site-specific assemblages. However, most of the temporal variation in species richness and beta diversity remained unexplained, suggesting a major role of other factors, such as seasonal discharge variations. Modelling of recharge rates for all the four springs over 2001–2020 suggested a potential >40% recharge deficit under dry conditions. Moreover, Cellular Automata-based modelling of rainfall over the Gran Sasso-Sirente hydrogeologic unit (feeding three of the four springs) predicted an overall precipitation decrease in the 2081–2095 period. Such changes could produce severe effects on springs’ microhabitats and related communities. Our results indicate that partitioning beta diversity, monitoring its temporal changes and assessing its environmental drivers are critical to evidence-based conservation of springs. Particularly, the high species turnover we have observed suggests that conservation strategies should seek to preserve as many microhabitats as possible within and among karst springs

Towards evidence-based conservation of subterranean ecosystems

Subterranean ecosystems are among the most widespread environments on Earth, yet we still have poor knowledge of their biodiversity. To raise awareness of subterranean ecosystems, the essential services they provide, and their unique conservation challenges, 2021 and 2022 were designated International Years of Caves and Karst. As these ecosystems have traditionally been overlooked in global conservation agendas and multilateral agreements, a quantitative assessment of solution-based approaches to safeguard subterranean biota and associated habitats is timely. This assessment allows researchers and practitioners to understand the progress made and research needs in subterranean ecology and management. We conducted a systematic review of peer-reviewed and grey literature focused on subterranean ecosystems globally (terrestrial, freshwater, and saltwater systems), to quantify the available evidence-base for the effectiveness of conservation interventions. We selected 708 publications from the years 1964 to 2021 that discussed, recommended, or implemented 1,954 conservation interventions in subterranean ecosystems. We noted a steep increase in the number of studies from the 2000s while, surprisingly, the proportion of studies quantifying the impact of conservation interventions has steadily and significantly decreased in recent years. The effectiveness of 31% of conservation interventions has been tested statistically. We further highlight that 64% of the reported research occurred in the Palearctic and Nearctic biogeographic regions. Assessments of the effectiveness of conservation interventions were heavily biased towards indirect measures (monitoring and risk assessment), a limited sample of organisms (mostly arthropods and bats), and more accessible systems (terrestrial caves). Our results indicate that most conservation science in the field of subterranean biology does not apply a rigorous quantitative approach, resulting in sparse evidence for the effectiveness of interventions. This raises the important question of how to make conservation efforts more feasible to implement, cost-effective, and long-lasting. Although there is no single remedy, we propose a suite of potential solutions to focus our efforts better towards increasing statistical testing and stress the importance of standardising study reporting to facilitate meta-analytical exercises. We also provide a database summarising the available literature, which will help to build quantitative knowledge about interventions likely to yield the greatest impacts depending upon the subterranean species and habitats of interest. We view this as a starting point to shift away from the widespread tendency of recommending conservation interventions based on anecdotal and expert-based information rather than scientific evidence, without quantitatively testing their effectiveness.Peer reviewe

Temperature effect on the sensitivity of the copepod Eucyclops serrulatus (Crustacea, Copepoda, Cyclopoida) to agricultural pollutants in the hyporheic zone

Abstract The sensitivity of freshwater invertebrates to agricultural pollutants is supposed to increase with rising temperature due to global warming. The aim of this study was to measure the effect of temperature on the lethal toxicity of ammonia-N, the herbicide Imazamox and the mixture of the two chemicals, in the adults and the juveniles of a population of the copepod Eucyclops serrulatus. This is a widely distributed species found in surface waters, in transitional habitats between surface water and groundwater, and in genuine groundwater environments. We tested the sensitivity by short-term bioassays (96 h) at 15°C and 18°C, respectively. Our results highlighted the following: (1) increasing temperature affected the sensitivity of the adults to ammonia-N and of the juveniles to the mixture, all of which were more sensitive to its detrimental effects at 18°C; (2) the juvenile stages were more sensitive than the adults to all toxicants, and (3) for all combinations of chemicals and temperatures, the effects were synergistic and approximately one order of magnitude greater than those expected according to a concentration addition model when comparing the LC50 for each chemical in the mixture with the LC50s of chemicals individually assayed. Overall, in a context of global change, ammonia-N and mixtures of agricultural pollutants may affect the survival rate of species that spend a part or the whole life-cycle in the hyporheic habitat, with detrimental effects to biodiversity and ecosystem services provided by the hyporheic biota

Collecting eco-evolutionary data in the dark : Impediments to subterranean research and how to overcome them

Caves and other subterranean habitats fulfill the requirements of experimental model systems to address general questions in ecology and evolution. Yet, the harsh working conditions of these environments and the uniqueness of the subterranean organisms have challenged most attempts to pursuit standardized research. Two main obstacles have synergistically hampered previous attempts. First, there is a habitat impediment related to the objective difficulties of exploring subterranean habitats and our inability to access the network of fissures that represents the elective habitat for the so-called "cave species." Second, there is a biological impediment illustrated by the rarity of most subterranean species and their low physiological tolerance, often limiting sample size and complicating laboratory experiments. We explore the advantages and disadvantages of four general experimental setups (in situ, quasi in situ, ex situ, and in silico) in the light of habitat and biological impediments. We also discuss the potential of indirect approaches to research. Furthermore, using bibliometric data, we provide a quantitative overview of the model organisms that scientists have exploited in the study of subterranean life. Our over-arching goal is to promote caves as model systems where one can perform standardized scientific research. This is important not only to achieve an in-depth understanding of the functioning of subterranean ecosystems but also to fully exploit their long-discussed potential in addressing general scientific questions with implications beyond the boundaries of this discipline.Peer reviewe

Groundwater is a hidden global keystone ecosystem

Groundwater is a vital ecosystem of the global water cycle, hosting unique biodiversity and providing essential services to societies. Despite being the largest unfrozen freshwater resource, in a period of depletion by extraction and pollution, groundwater environments have been repeatedly overlooked in global biodiversity conservation agendas. Disregarding the importance of groundwater as an ecosystem ignores its critical role in preserving surface biomes. To foster timely global conservation of groundwater, we propose elevating the concept of keystone species into the realm of ecosystems, claiming groundwater as a keystone ecosystem that influences the integrity of many dependent ecosystems. Our global analysis shows that over half of land surface areas (52.6%) has a medium‐to‐high interaction with groundwater, reaching up to 74.9% when deserts and high mountains are excluded. We postulate that the intrinsic transboundary features of groundwater are critical for shifting perspectives towards more holistic approaches in aquatic ecology and beyond. Furthermore, we propose eight key themes to develop a science‐policy integrated groundwater conservation agenda. Given ecosystems above and below the ground intersect at many levels, considering groundwater as an essential component of planetary health is pivotal to reduce biodiversity loss and buffer against climate change