Towards evidence‐based conservation of subterranean ecosystems

Abstract

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 metaanalytical 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.

A dataset of European marine mites (Trombidiformes, Halacaridae)

“…The accumulation of high-quality spatial distribution data of species in space and time is critical to ascertain not only the current extent of biodiversity losses but also its long-term effects (Magurran et al 2010, Oliver 2016, which are pivotal to ensure effective decision-making processes. Detailed information on species' distribution is not only important regarding the protection of a particular area or the assessment of spatial trade-offs between ecosystem services, but also to decide on conservation priorities and communicate about the implementation of policies (Martinez-Harms and Balvanera 2012, Townsend et al 2014, Mammola et al 2022.…”

Life history observations of the Illinois state endangered Enigmatic Cavesnail, Fontigens antroecetes (Hubricht, 1940) made under simulated cave conditions

“…In a recent review of actions and policies aimed at conservation of subterranean gastropod diversity in North America, Gladstone et al (2021) highlighted the potential usefulness of captively propagating sygobitic snails in gaining information on life history and reproductive biology. Captive propagation could also be an important strategy in reintroduction efforts should isolated populations experience declines or extirpation (Mammola et al 2022). Here I present life history information for F. antroecetes gained through captive breeding under simulated cave conditions, the first such published account for a stygobitic snail.…”

The promise and perils of engineering cave climates: response to Turner et al.

“…For example, it is now well understood that warming of subterranean systems will push specialized species toward their critical thermal limits (Pallarés, Colado, et al., 2020), climate change will facilitate the spread of potentially pathogenic microbes underground (McClure et al., 2020), and different drought‐related stressors will affect the availability and quality of groundwater (Famiglietti, 2014; Jasechko & Perrone, 2021; Wu et al., 2020). Although similar problem‐diagnosis studies are undoubtedly important, there is a shortage of solutions that can be implemented to anticipate and combat these forecasted impacts (Mammola, Cardoso, et al., 2019; Mammola et al, undefined; Wynne et al., 2021). The question remains: What can be done to practically deal with these predicted negative trajectories?…”

“…However, ecosystem manipulation should follow strict guidelines to avoid unintended consequences to nontarget species (Simberloff & Stiling, 1996). Given that the conservation of subterranean ecosystems is finally gaining ground (Wynne et al., 2021), we believe it is of fundamental importance to tread lightly when considering interventions that directly affect the subterranean ecosystem (Mammola et al, 2022).…”

“…Climate change is accelerating (Ripple et al, 2021), and the effects are already visible underground (Mammola, Piano, et al, 2019;Sánchez-Fernández et al, 2021), creating the urgent need for bold practical solutions, such as the one suggested by Turner et al However, ecosystem manipulation should follow strict guidelines to avoid unintended consequences to nontarget species (Simberloff & Stiling, 1996). Given that the conservation of subterranean ecosystems is finally gaining ground (Wynne et al, 2021), we believe it is of fundamental importance to tread lightly when considering interventions that directly affect the subterranean ecosystem (Mammola et al, 2022).…”