The impact of man-made water bodies on local biodiversity: two cases

Introduction

Biodiversity is the bedrock of the sustainable functioning of ecosystems in a changing environment and of maintaining the biosphere’s suitability for human habitation, meeting human needs, and promoting sustainable development. The decline in biodiversity, particularly in freshwater environments, is a global phenomenon driven by multiple interconnected factors (Britton et al., 2023; Dudgeon and Strayer, 2025). Growing evidence suggests that freshwater ecosystems are entering a new phase in which alien species play a dominant role, altering ecological processes and driving unforeseen transformations (Bolpagni, 2021). Human actions are the principal causes of this decline and homogenization, although freshwater ecosystems can remain diverse despite intensive human pressures (Dudgeon, 2003; Gopal, 2013). To mitigate biodiversity loss and catastrophic changes, it is crucial to understand the core principles of the current factors and mechanisms that affect freshwater species’ distribution and persistence across different spatial and temporal scales.

The current work aims to further validate the hypothesis that artificial water bodies significantly contribute to enhancing regional biodiversity. using results on small lakes created by gold mining near Lake Baikal and the North Crimean Canal. These bodies of water have been examined and documented by the authors before (Shadrin et al., 2023, 2025; Anufriieva et al., 2026).

Artificial water bodies in our world

From ancient times, human actions, including construction, irrigation, water management, and mining, have profoundly altered the landscape, creating new water bodies and altering existing natural ones into natural-technological hybrids (Kurlansky, 2002; Anufriieva et al., 2020; Shadrin et al., 2023). Lake Yuncheng (China) has been a site for salt production for over 5,000 years and is one of the oldest examples of a natural saline lake transformation into a hybrid natural-technological water body (Han and Park, 1999; Kurlansky, 2002; Anufriieva et al., 2020). The first man-made canals and lakes/ponds on the planet likely began to appear no later than 8,000–9,000 years ago, as irrigation systems in areas with insufficient rainfall for crop cultivation (Anufriieva et al., 2020). The first appeared around 6000 BC in Mesopotamia (Lawton and Wilke, 1979; Huang et al., 2021). The Indus Valley Civilization built irrigation canals and reservoir systems at Girnar in 3000 BC (Thomas and Fulkerson, 2021). In the Andes (Peru), the remains of irrigation canals were discovered, radiocarbon-dated to the fourth millennium BC, with traces under one canal dating to the fifth millennium BC (Dillehay et al., 2005). Discharging agricultural drainage water from irrigated fields led to the formation of artificial lakes as examples, three within the Fayoum desert depression (Anufriieva et al., 2020). Currently, the total length of such canals is enormous, and the area irrigated continues to grow, as does the total length of canals. Another type of canal is navigational, with over 63,000 km currently existing worldwide. In Europe alone, 30 major canals and 100 branches (28,000 km) connect 350 ports (Ketelaars, 2004; Galil et al., 2008).

On our planet, there are more than 4 million water bodies, with artificial ones making up at least half of the total, and both the number of these bodies and their global importance are increasing (Smith et al., 2002; Straškraba, 2004; Saulnier-Talbot and Lavoie, 2018; Izmailova and Korneenkova, 2022; Wang et al., 2022). Thus, artificial and hybrid water bodies are integral components of the modern biosphere everywhere.

When trying to understand the global causes of biodiversity loss, one must not lose sight of the fact that there is no independent evolution of individual species; the global biosphere acts as a single complex system in evolutionary transformations (Shadrin, 2024). To achieve a thorough comprehension of this subject, it is essential to differentiate between two key dimensions: 1. the global and local external factors that influence shifts in species diversity, and 2. the internal mechanisms of biological interactions within the biosphere, which operate at various scales and can result in both cyclical and directional alterations to biological composition (Galil et al., 2008; Anufriieva and Shadrin, 2018; Suding et al., 2024). In this article, we will focus on the first aspect, specifically addressing the construction and proliferation of artificial water bodies, canals, and lakes.

Technogenic lakes after gold mining: the case of the river Bol’shiye Koty (Baikal region)

Gold-mining operations that involve dredging have profound and lasting impacts on the physical landscape and on aquatic and terrestrial environments in forest river valleys across the globe (Davies et al., 2020; Lawrence et al., 2021; Pérez-Aristizábal et al., 2025). These activities create diverse landscapes characterized by numerous small water bodies, and impacts persist not only during mining but also for an extended period afterward. In 1839, gold was discovered in rivers along Lake Baikal’s western shore, sparking a gold rush in the Bol’shie and Malye Koty rivers, which flow into Lake Baikal. Historical records indicate that gold mining began in these rivers in 1856 (Kozhova, 1984; Sukhodolov, 2017). Initially, gold was extracted manually. In 1937–1938, a mechanical dredge arrived on the River Bol’shie Koty. By 1953, the original dredge was replaced by a more robust machine, which operated until the mid-1970s. Dredging is possible only in deep, extensive reservoirs. Therefore, dams with large reservoirs were built along the river to support these operations. After mining a stretch of the river, the dredging equipment is moved upstream. The dam is then dismantled. The duration of dredging in a particular area was directly proportional to the amount of gold present, leading to the formation of larger heaps and deeper troughs. The landscape underwent a complete makeover. Hollows filled with water, creating lakes and puddles up to 1–2 meters deep. In the Bol’shie River valley, the forest landscape is dotted with hills of boulders of varying sizes, interspersed with pebbles and sand, as well as sinkholes from mining, resulting in over 30 artificial lakes. These lakes vary in their connections to each other and to the river (Figures 1, 2). The concept that water bodies, connected by the exchange of energy, nutrients, and a variety of organisms, should be considered a unified metaecosystem is gaining widespread acceptance (Chase et al., 2020; Philipp et al., 2025). The entire set of species can be characterized as a metacommunity, a complex adaptive system (Deosti et al., 2024). All artificial lakes interconnected with the river form a single, interconnected metaecosystem.

The fauna and ecology of these lakes and nearby rivers were first studied between 2022 and 2025 (Shadrin et al., 2025; Anufriieva et al., 2026). The valleys of the Chernaya and Malye Koty rivers confine the research territory. This region features a basin with a rounded shape, surrounded on three sides by the Primorsky Ridge and its branches, and bounded by Lake Baikal on the fourth. (Figure 1). The principal subjects of investigation included seven unnamed artificial lakes, as well as the Bol’shie Koty, Malye Koty, Zhilishche, and Chernaya rivers, which drain into Lake Baikal. Each lake is small, measuring less than 0.001 square kilometers. They varied significantly in appearance. These lakes form a unified hydrological network linked to the Bol’shie Koty River. These lakes constitute a cohesive hydrological system that is connected to the Bol’shie Koty River. For about eight months each year, they are usually covered by ice, and from November to March, anoxic conditions typically prevail in these lakes (Shadrin et al., 2025). Frozen lakes and extended winters, with prolonged periods of anoxia, present severe challenges to the animals that live there. Lakes and rivers are situated in a forested area and are shaded in varying degrees depending on topographical features and nearby vegetation. Significant spatial and diurnal fluctuations in abiotic factors were recorded during the summers of 2022, 2024, and 2025, both within and among the water bodies (Anufriieva et al., 2026). Primary producers varied based on shading, substrate, and depth. Benthic biofilms, filamentous alga Ulothrix sp., floating mats of moss Fontinalis antipyretica Hedw., and/or some aquatic flowering plants were the main contributors to primary production.

In total, 74 species, belonging to 6 phyla, and 10 classes of invertebrates were recorded in the man-made lakes and rivers (Table 1): Arthropoda accounted for 86% of all species with: class Collembola (1 species), class Arachnida (2 species), subphylum Crustacea (20 species): class Branchiopoda (8 species), class Copepoda (7 species), class Ostracoda (4 species), class Malacostraca (1 species), class Insecta: order Diptera (33 species), order Hemiptera (1 species), order Trichoptera (1 species), order Ephemeroptera (3 species), order Plecoptera (1 species). Benthic animal species were always present in plankton samples. Fish schools of Phoxinus phoxinus Linnaeus, 1758 were found in two lakes; during hot days, they were in shaded areas of the lakes or under floating mats of moss F. antipyretica.

Table 1. Invertebrate species found in the surveyed rivers and man-made lakes during 2022, 2024, and 2025 (from Anufriieva et al., 2026).

• species was not present.

+ species present.

A total of 34 invertebrate species were found in the studied rivers Bol’shiye Koty, Malye Koty, Zhilishche, and Chernaya (Table 1). A total of 68 species were discovered in technogenic lakes, with 59% species not documented in rivers. Six species were found only in rivers but never in man-made reservoirs: Bosmina longirostris (O.F. Müller, 1785), Dactilobyotus dispar (Murray, 1907), Heptagenia flava Rostock, 1878, Baetis rhodani (Pictet, 1843), Thienemannia gracilis Kieffer, 1909, and Pentapedilum exsectum Kieffer, 1916. The comparison of species complexes between rivers and lakes reveals significant differences, as evidenced by the Jaccard (0.378) and the Chekanowski-Sørensen (0.549) coefficients. The authors conclude that the appearance of artificial water bodies along the Bol’shiye Koty River has enhanced the diversity of local aquatic invertebrates without evidence to suggest that the introduction of new species has led to the disappearance of any native species (Anufriieva et al., 2026). It’s challenging to fully assess how newly evolved species affect local ecosystems, mainly because we lack detailed data. The increase in aquatic meta-ecosystem productivity and the enhancement of trophic connections with forest communities, as example, through the development of adult amphibious insect species.

Alien species: arrival and integration into local ecosystems

New alien species are constantly arriving here by natural ways, either actively or passively. However, they were unable to establish a foothold, i.e., create populations here, because there were no suitable habitats. Technogenic lakes have acted as such habitats for them. Once introduced into a water body, a new species faces various ecosystem filters – abiotic and biological – before it can establish itself (Shadrin, 2024; Bernardo-Madrid et al., 2025; Shadrin et al., 2027).

As the frequency of occurrence increases in lakes, the number of species exhibiting that frequency declines. This relationship can be approximated using a power-law equation. (R = - 0.983, p = 0.0005):

(1) Kf= 93.42 F-1.238

where K_f is the number of species found with a frequency of occurrence F, in %.

Twenty-nine invertebrate species – 39% of the total were found only once. About 72% of all species appeared less than 10% of the time, 22% appeared between 11 and 40% of the time, and only 7% appeared more than 40% of the time. In the meta-ecosystem of the Tazheran lakes, a similar pattern emerged (Shadrin et al., 2027):

(2) Kf= 185.0 F-1.11

The exponential coefficients of Equations 1 and 2 are statistically indistinguishable; therefore, from a comparison of these two equations, we can draw the following preliminary conclusions: 1. The ratio of species by occurrence across communities and meta-communities is not haphazard. Instead, it reveals a consistent pattern in the organization of species structure. 2. The meta-community of these technogenic lakes has already taken shape. A specific metazoocoenosis structure was proposed based on species frequency, which divides all species into three groups (Shadrin, 2024). Species that appear more than 40–50% of the time form the core of the metazoocoenosis, making up no more than 10% of all species. A shell can be identified around the core, comprising species with occurrence frequencies of 10–20% or less; these species account for approximately 50% of the total species richness. The third category, species within the ‘cloud’, includes approximately 40% of the total diversity in this context; these species are relatively rare. Gene space exhibits a comparable architecture – comprising a core, a shell, and a cloud – at various levels of complexity (Koonin, 2012).

Probably, the core species and, to a significant degree, the shell constitute stable elements within a regional pool. At any given time, all these species are present within the regional metaecosystem, either actively engaged or in a dormant phase. Species of a cloud are not the fixed components of the regional species inventory. They occasionally enter it through random active migration, such as insects during their flying phases, or others, such as crustaceans and rotifers, travel long distances passively, often in dormant forms, carried by wind, animals like birds, or humans (Hessen et al., 2019; Green et al., 2023). This component of species diversity is reconfigured quite regularly; most newly introduced species do not form self-sustaining populations. A thorough investigation of invasive species in Romania identified 297 distinct species, with 57% occurring only once (Preda et al., 2026). This generalization confirms our assumption that a significant proportion of invasive species do not create stable populations. Being a species accidentally introduced and becoming part of local biodiversity are generally not the same thing. So, regional species diversity does not increase due to them. The proposed arrangement is, admittedly, somewhat preliminary. Additional data from diverse aquatic metaecosystems are essential to either substantiate or refine this hypothesis or to disprove it.

Such human activities may also increase the likelihood of a new species arriving in a local area. In our case, migratory waterbirds, as observed, visited artificial lakes; we hadn’t noted such visits to river stretches during our investigation. These birds are known to carry alien invertebrate species.

Even neighboring aquatic ecosystems, where invasive species might accidentally find their way, can exist in two distinct states: coherent and incoherent. Ecosystem immunity, the capacity of ecosystems to resist introductions of new species, is high in coherent states. In contrast, incoherent, newly formed, or destabilized ecosystems have low ecosystem immunity (Anufriieva and Shadrin, 2018). Globally, constructed water bodies harbor more non-native species than their natural counterparts (Parkes and Duggan, 2012; Anufriieva and Shadrin, 2016; Duggan et al., 2018; Naselli-Flores and Marrone, 2019). The likelihood of an alien species being introduced, for example, by birds, is practically independent of the state of the water body’s ecosystem. However, the chance of it becoming established in a new habitat is much higher in a new or highly destabilized ecosystem.

Man-made canal and biodiversity changes. a case of the North Crimean Canal

The North Crimean Canal (NCC), constructed between 1963 and 1976, was engineered to address the acute freshwater shortage on the Crimean Peninsula (Shadrin et al., 2023). Before the destruction of the Kakhovka Dam in 2023, it was Europe’s longest canal (Figures 3, 4). The main channel stretched 403 kilometers, and its branches totaled over 10,000 kilometers. Before 2014, the NCC supplied 1.5 billion cubic meters of water each year, far exceeding Crimea’s combined surface and groundwater flows by a factor of 1.5 (Gorlov, 2025). The construction project significantly altered aquatic and terrestrial ecosystems in Crimea’s arid part. The canal’s construction led to the desalination of numerous hypersaline lakes. Lake Kyzyl-Yar, once a hypersaline body of water, became a freshwater lake (Shadrin et al., 2018a). In the hypersaline Bay Sivash (Sea of Azov), salinity has significantly decreased; most of its area has become a brackish water body, near the coast, due to the discharge of freshwater from irrigated lands, and in several places, large freshwater areas have formed (Shadrin et al., 2018b).

The construction opened up a new pathway for alien species to migrate from the Dnieper River basin to the peninsula. The likelihood of alien species invading Crimea has significantly increased. Molluscum species that had not been present before were discovered in the canal and later in other inland waters of the peninsula: Dreissena bugensis Andrusov, 1897, Dreissena polymorpha (Pallas, 1771), Viviparus viviparus (Linnaeus, 1758), Lithoglyphus naticoides (Pfeiffer, 1828), Theodoxus fluviatilis (Linnaeus, 1758), Esperiana esperi (A. Férussac, 1823), Lymnaea stagnalis (Linnaeus, 1758), Ampullaceana balthica (Linnaeus, 1758) (Son, 2010). The NCC system, which includes canals of various levels as well as ponds and reservoirs, harbors 40 species of freshwater fish belonging to the Dnieper fauna, none of which are found in the rivers of Crimea (Karpova, 2016).

In 2014, due to political considerations, the flow of water from the Dnieper River to the canal was halted (Shadrin et al., 2018b), causing the channel to dry up over most of its length (Figure 3). In early 2022, the Dnieper water flow briefly resumed (Figure 3). During this period, scientists studied zooplankton in the canal (Shadrin et al., 2023). A total of 11 species of Rotifera, 11 species of Cladocera, and 15 species of Copepoda were identified in the plankton samples. Among the 37 species identified in the NCC, 10 had not been previously recorded in the water bodies of Crimea. These newly discovered rotifers included Ploesoma hudsoni (Imhof, 1891), Polyarthra dolichoptera Idelson, 1925, Pompholyx complanata Gosse, 1851, Synchaeta grandis Zacharias, 1893, and Synchaeta stylata Wierzejski, 1893. Among Cladocera, Bosminopsis zernowi Linko, 1901, Disparalona rostrata (Koch, 1841), and Scapholeberis mucronata (O. F. Müller, 1776), which had not been noted before in Crimea. Finally, for Copepoda, Eurytemora lacustris (Poppe, 1887) and Cyclops smirnovi Rylov, 1948 were first documented in Crimea. All these species, except C. smirnovi, had been previously identified in the Dnieper reservoir system and/or in the rivers that feed into the Dnieper. C. smirnovi, a rare valid species, was previously thought to be abundant only in a high mountain lake in Altai (Western Siberia) during the first half of the 20th century. This species was probably introduced to the new region through migratory birds; a similar path has been observed for several Asian cyclopoid copepods that have recently established themselves in Crimea (Anufriieva et al., 2014).

Inland canals provide conduits for nonnative species to spread between previously distinct biogeographic regions (Nunes et al., 2015). The construction of canals greatly increases the likelihood of alien species entering the new area. In Europe, 44% of freshwater invasive species have spread to new regions via inland canals (Nunes et al., 2015). Canals, like other man-made water bodies, also generate novel habitats, thereby enhancing the potential for alien species to establish populations (Shadrin et al., 2018a). However, it is growing clearer that the role of constructed canals in biodiversity dynamics extends beyond simply facilitating the spread of alien species (Chester and Robson, 2013; Tölgyesi et al., 2022); they also frequently serve as hotspots of aquatic biodiversity and refuges for rare species (Gómez and Araujo, 2008; Dorotovičová, 2013; Sousa et al., 2019). To fully understand the complex influence that canals have on regional species diversity and its maintenance, it is crucial to undertake further investigation and re-examine current understanding from a fresh perspective.

Conclusion

Artificial water bodies that have undergone extensive modifications pose a heightened risk of aiding the introduction of new invasive species into their ecosystems. This observation is not groundbreaking; it has long been established and widely recognized. It’s essential to grasp that this phenomenon arises from two distinct factors: the establishment of new pathways that enable species to extend their habitats beyond their natural boundaries, and the emergence of novel aquatic environments characterized by nascent ecological communities, i.e., ecosystems that are still in the process of developing, incoherent stages. Each water body is unique, and understanding this is crucial. When analyzing any water body at a given moment, it’s essential to discern its current state. If we accept the three-element structure of the totality of the noted species (core, shell, cloud), then the question remains open: can all accidentally transported aquatic invertebrate species in the cloud be considered part of the regional biodiversity? This suggests the necessity of reevaluating the notion of regional and local biodiversity, avoiding its simplification to a mere enumeration of species ever encountered in a particular region.

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Footnotes

Edited by: Yulia Bespalaya, N. Laverov Federal Center for Integrated Arctic Research of the Ural Branch of the Russian Academy of Sciences, Russia

Reviewed by: Husain Latuconsina, Universitas Islam Malang, Indonesia

Alfonso Guillermo Banderas Tarabay, Instituto Mexicano de Tecnología del Agua, Mexico