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

Abstract

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.

Regional climate contributes more than geographic distance to beta diversity of copepods (Crustacea Copepoda) between caves of Italy

“…Further, we demonstrated that copepod assemblages populating a set of caves along a latitudinal gradient spanning the Italian peninsula were noticeably dissimilar from one another, with turnover rather than nestedness driving most of the observed beta diversity. This is also important from a conservation perspective because the high species turnover implies that environmental degradation within a single cave may lead to the loss of unique species not occurring elsewhere, similarly to what has emerged from a recent study performed on groundwater-fed karst springs 41 . Additionally, we showed that geographical distance had a not negligible yet secondary role in shaping the between-cave dissimilarity of copepod assemblages in our studied caves, with surface temperature patterns having the greatest influence, particularly on species replacement.…”

“…Nevertheless, only a few studies 33 , 36 have thus far evaluated the relative role of geographic distance and environmental gradients on biotic dissimilarity (i.e., beta diversity) of groundwater crustacean assemblages, explicitly partitioning between spatial turnover and nestedness-resultant dissimilarity 37 . Partitioning beta diversity into these two components and exploring its geographic, historical, and environmental correlates has proven to be crucial for understanding biogeographic processes 36 , 38 , 39 and outlining conservation priorities 40 , 41 .…”

Characteristics of Groundwater Microbial Community Composition and Environmental Response in the Yimuquan Aquifer, North China Plain

“…Natural spring areas, as the unique zones where groundwater and surface water converge, boast abundant water resources and distinct ecological environments [1,2]. Research on environmental microbial communities and their functions holds significant implications worldwide [3]. In recent years, it has been discovered that microbes in groundwater environments play vital roles in maintaining aquatic ecological stability, protecting water resources, and safeguarding ecosystem health [4][5][6].…”