Mediterranean springs: Keystone ecosystems and biodiversity refugia threatened by global change

Abstract

Mediterranean spring ecosystems are unique habitats at the interface between surface water and groundwater. These ecosystems support a remarkable array of biodiversity and provide important ecological functions and ecosystem services. Spring ecosystems are influenced by abiotic, biotic, and anthropogenic factors such as the lithology of their draining aquifers, their climate, and the land use of their recharge area, all of which affect the water chemistry of the aquifer and the spring discharges. One of the most relevant characteristics of spring ecosystems is the temporal stability of environmental conditions, including physicochemical features of the spring water, across seasons and years. This stability allows a wide range of species to benefit from these ecosystems (particularly during dry periods), fostering an unusually high number of endemic species. However, global change poses important threats to these freshwater ecosystems. Changes in temperature, evapotranspiration, and precipitation patterns can alter the water balance and chemistry of spring water. Eutrophication due to agricultural practices and emergent pollutants, such as pharmaceuticals, personal care products, and pesticides, is also a growing concern for the preservation of spring biodiversity. Here, we provide a synthesis of the main characteristics and functioning of Mediterranean spring ecosystems. We then describe their ecological value and biodiversity patterns and highlight the main risks these ecosystems face. Moreover, we identify existing knowledge gaps to guide future research in order to fully uncover the hidden biodiversity within these habitats and understand the main drivers that govern them. Finally, we provide a brief summary of recommended actions that should be taken to effectively manage and preserve Mediterranean spring ecosystems for future generations. Even though studies on Mediterranean spring ecosystems are still scarce, our review shows there are sufficient data to conclude that their future viability as functional ecosystems is under severe threat.

The Cultural Ecohydrogeology of Mediterranean-Climate Springs: A Global Review with Case Studies

“…Mediterranean springs provide essential ecosystem services that sustain the integrity of adjacent upland ecosystems, as well as socio-cultural development and practices [12,20]. The small size of most spring ecosystems causes them to be overlooked in many scientific and resource management analyses, but belies their high degree of ecological complexity, ecosystem individuality, collective heterogeneity, and cultural significance [275,280].…”

“…Dramatic discharge reduction in small-flow Mediterranean springs was documented (e.g., [12]), who also highlighted that it is imperative to prioritize the conservation of Mediterranean springs and develop specific management plans for these ecosystems. This review, with its emphasis on cultural values, underlines the cultural valuation of spring ecosystems in MCZs, also fostering new ways to achieve this goal, as a mitigation strategy of the detrimental effects of climate change.…”

“…Upland MCZ vegetation is well described [12,44,45], but several additional points are worth noting. MCZs occur in topographically complex landscapes, with vegetation transitioning from coastal sclerophyllous shrublands to broad-leafed or other forest types farther inland.…”

“…Perennial groundwater-fed springs and streams in MCZs are recognized as unique ecosystems, often hosting algal, macroinvertebrate, and fish species with strongly seasonal life history traits [12,[48][49][50][51]. Pascual et al (this article) and [52] described the biodiversity of 10 springs in the karstic terrains of the Montsant Massif south of the Catalan pre-coastal ranges in the north-eastern Iberian Peninsula, and a further 10 springs in the Serra de Tramuntana Range on the island of Mallorca, reporting 500 and 363 species, respectively, of macroalgae, diatoms, bryophytes, cormophytes, aquatic invertebrates, and vertebrates.…”

“…While the ecological and cultural sustainability of MCZs and springs around the world are recognized as critically important, the inter-relationships between springs and cultural development in MCZs have only begun to receive attention, and many recent works on hydrological, cultural, and historical aspects have little to no coverage of the topic. However, such information is increasingly important, particularly in heavily populated, arid MCZs as global warming further exacerbates weather instability and fresh groundwater availability, in turn affecting safety, food production, commerce, and politics [8][9][10][11][12].…”