Keywords

1 Introduction

Until the end of the last century, Patagonia tended to evoke images of the Argentine pampas, while a vast area west of the Andes between Puerto Montt and the Strait of Magellan, with fjords and canals, extensive temperate rainforests, lakes, rivers, and ice fields, was largely ignored. The name Chilean (western) Patagonia is recent, and this is perhaps a fitting preamble to the state of knowledge of the freshwater ecosystems of Chilean Patagonia, which remains incipient. This lack of knowledge is paradoxical, considering the ecological and social importance of these systems that we are now beginning to appreciate.

Southwestern Patagonia is home to the largest rivers west of the Andes, some of the largest lakes on the continent and among the deepest in the world, as well as the most extensive temperate ice fields on the planet. Most of Chile's fresh water is located in Patagonia. Other unique features include active volcanoes, volcanic soils, limited effect of global atmospheric contaminants, convergence of biogeographic provinces including Gondwanic elements, and low species richness but high endemism. Therefore, these ecological systems may have a globally unique composition and function.

Nonetheless, Patagonian freshwater ecosystems are poorly represented in global inventories [2, 73, 92]. There are serious deficiencies in the basic description of Patagonian freshwater ecosystems with respect to their hydrology and ecosystem function. There are only sporadic biodiversity records and distribution ranges tend to be underestimates. The gaps in knowledge correspond to a shortage of researchers who work in this Patagonian area. For example, for an analogous region, the book “Freshwaters of New Zealand” [66] had the contribution of 64 specialists, many of whom are recognized worldwide. In Chilean Patagonia (Fig. 1), a territory three times the size of New Zealand, there are only a handful of researchers working on freshwater systems.

Fig. 1
A physical map of southern Chile and Argentina. Chile is on the left with Argentina on the right. Some of the watersheds on the Pacific and Atlantic between both borders are R Petrohue, R Chamiza, R Puelo, R Gallegos, R Ciaike, and R Grande.

Physical map of southern Patagonia showing the main Pacific and Atlantic watersheds referred to in this chapter. The study area, referred to as southwestern Patagonia, includes all watersheds (only the major basins are delineated) draining into the Pacific Ocean or its channels and fjords. Note the high incidence of trans-Andean and binational watersheds typical of the study area

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In spite of the small area occupied by freshwater ecosystems, they harbor a biodiversity and proportion of species of conservation concern an order of magnitude greater than terrestrial or marine environments [48, 127]. Almost 30% of all at-risk taxa (designated of conservation concern) in the Los Lagos, Aysen, and Magallanes regions are freshwater species. Meanwhile, there is a great contrast between global vs. regional threats to freshwater biodiversity,only half of the emerging threats (sensu Reid et al. [111]) appear to be relevant to Patagonian ecosystems. Many of the threats noted for freshwater fish in Chile are applicable to populated areas (33°–41° S). This leads to a crucial point in terms of prioritizing and planning conservation in Chilean Patagonia—impacts and threats to aquatic ecosystems and conflicts over water resources are still relatively minor, so conservation efforts have a higher probability of success. This goes hand in hand with the observation that an important part of the diversity of amphibians, native fish, and aquatic insects in Chile is found within the geographic range of western Patagonia.

Chilean Patagonia has been recognized as an area of global importance for conservation [25, 92], and is also one of the few regions on the planet that already has >50% of its territory legally protected, the cornerstone of the half-earth concept promoted by Wilson [150] for biodiversity conservation. This chapter also emphasizes the less prominent part of Wilson's model, which focuses on the efficient and sustainable use of the other half of the that lies outside protected areas: this perspective is necessary in terms of the conservation of freshwater ecosystems, and Patagonia is no exception. This chapter is therefore complementary to Astorga et al. [13], in relation to the overarching priority of protecting headwater streams and undisturbed forested watersheds. Here we also emphasize the conservation status of Patagonian biodiversity and freshwater ecosystems located downstream, and often outside protected areas. The purpose of this chapter is to consolidate most relevant information and evaluate from different perspectives the conservation of freshwater systems in southwestern Patagonia, and to provide some strategic recommendations.

2 Scope and Objectives

We emphasize the importance of a hydrographic definition of the conservation of Patagonian freshwater systems, one based on drainage basins, rather than a political regionalization. The freshwater ecosystems of southwestern Patagonia constitute a unique area of often binational watersheds that drain to the Pacific Ocean via an intricate system of fjords and channels, from Chiloé to Cape Horn. Our study area comprises the basins with western slopes south of 41° S, which is predominantly Chilean, but also Argentinean (Fig. 1), which drain into and exert a tremendous influence on these interior seas, an area which we will refer to hereafter as southwestern Patagonia.

In this chapter we advance the idea that this territory offers excellent opportunities for the conservation of biodiversity and freshwater ecosystems at the landscape scale. Recommendations for improving the conservation of freshwater systems, include water resource policy research, planning actions, management, and education, with examples of conservation initiatives and tools used in other similar regions of the world.

3 Freshwater Ecosystems of Southwestern Patagonia

3.1 Western Patagonian Hydrography: Classification, Distribution, and National Importance

Southwestern Patagonia represents most of Chile's water resources. According to the Chilean Water Atlas (Directorate General of Water, 2016; in Spanish Dirección General de Aguas), almost all waterbody types or forms of water resources in the study area (Los Lagos, Aysen, and Magallanes Regions) place Patagonia as the area with the highest percentage contribution to the country’s total water resources (Table 1). Some freshwater systems are treated in greater depth in other chapters: Rivera et al. [116] for glaciers, and Mansilla et al. [84] for wetlands.

Table 1 Importance for Chile of the main water resources of southwestern Patagonia*
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Despite the division of freshwater ecosystems across chapters, we emphasize that glacier and wetland systems are an integral part of the water systems that feed, regulate, and interact with the water bodies discussed here. The following is a summary of the general characteristics of freshwater systems in the Patagonian study area.

3.1.1 Lakes and Ponds

Southwestern Patagonia has some of the largest lakes in Chile, and the second largest lake in South America (Lake General Carrera/Buenos Aires). These lakes are generally deep (>100 m). Because of the rugged Andean topography of this area and its glacial-tectonic origin, there are also two of the ten deepest lakes in the world (O'Higgins at 810 m and General Carrera at 580 m), although they do not appear in the global lists [73]. Binational and trans-Andean lakes, whose names differ between Chile and Argentina (Fig. 1), exclusive to western Patagonia, often appear truncated on official maps, and are hence poorly underappreciated in the public policy sector [46, 93]. Only a handful of the 184 major lakes identified in southwestern Patagonia have been subject to basic field observations [28, 29]. These lakes are thought to be oligotrophic or ultra-oligotrophic, due to the scarcity of nutrients and the depth of mixing induced by strong winds [51, 123]. Ponds, on the other hand, are 50 times more abundant than lakes [90], although a complete catalogue does not yet exist. They are usually shallow, dominated by littoral habitat, abundant aquatic vegetation, rich in organic matter and highly productive. They provide critical habitat for birds, amphibians, and invertebrates. Most ponds are connected to drainage networks, but there are also endorheic or isolated systems. Consequently, there are ponds with and without fish, the presence or absence of which may have a profound impact on the trophic web and biodiversity [102, 124]. Some of the endorheic ponds are hypersaline, and have a distinctive ecological function [57, 124, 153].

Apart from these generalizations, and in contrast with over 20 years of lake monitoring from 41° S (Lake Llanquihue) northward [46], background information on lakes in southwestern Patagonia is very scarce.

3.1.2 Rivers

Six of Chile's largest rivers (width > 300 m; flow > 600 m3/s) are located in southwestern Patagonia: Puelo, Yelcho, Palena, Aysén, Baker, and Pascua rivers (Fig. 1, Table 2). Although the river networks in the region are several hundred thousand kilometers in length, the individual rivers are relatively short (<300 km), because the Andes range lies so close to the coast. Perhaps for this reason, the rivers of this region tend to be invisible at the continental level. For example, the World Wildlife Fund inventory [2] only lists the water bodies on the Patagonia ecoregion’s eastern slope (in Argentina), which have longer and more visible trajectories but less flow.

Table 2 Attributes of the main watersheds of southwestern Patagonia
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From the headwaters in Patagonian peaks, ice fields and arid zones, Patagonian rivers often traverse mountain foothills and low-gradient coastal plains, ultimately discharging into fjords; the full range of fluvial habitats present in the temperate zone is probably represented in the Patagonian region. These contrasting landscapes in a relatively small area are perhaps what most distinguishes southwestern Patagonia river systems. At the same time, the variability, complexity, and network structure of river ecosystems pose a major challenge for the conservation of freshwater biodiversity in Chile.

Southern Patagonia dominates the total runoff in the western Andes [92]. Since the coastal landscape of southwestern Patagonia has an intricate arrangement of archipelagos, fjords, and inland waters, the coupling of river discharges to marine ecosystem function is perhaps more intense than anywhere else in the world, a feature that is just beginning to be appreciated [78, 133, 132]. This coastal zone has the highest rainfall in Chile and among the highest globally and has innumerable coastal watersheds that also contribute diffuse inputs (e. g. not recorded in Table 2). For example, the Madre de Dios Archipelago, with up to 9,000 mm rainfall per year, can produce the equivalent of 25% of the runoff of the Baker River basin which has tenfold greater surface area.

3.1.3 Ground Water

Groundwater reserves in saturated sediments and rock fissures located in geological formations known as aquifers, are both sources of freshwater flows and also habitat for freshwater organisms. Groundwater resources are better characterized and more exploited in central and northern Chile than in Patagonia. The aquifer inventory of the [46] does not include any aquifers in the Aysén and Magallanes regions. However, it is clear that aquifers are abundant in southwestern Patagonia, because of the extensive distribution of unconsolidated Quaternary material (fluvial and moraine deposits). Because of this, the aquifers of the region probably receive greater contribution from local precipitation, in contrast to regional flow typical of the central Andes. Even though their potential distribution is very heterogeneous, these aquifers probably constitute the second most important water reservoir in southwestern Patagonia, comparable to global patterns in freshwater distribution. Evidence of the widespread importance of ground water may be seen in the continuous flow of streams during periods without precipitation (base flow) and the upwelling of water in flood plains and headwater streams. The aquifers of western Patagonia also have social importance, shown by hundreds of groundwater rights or springs granted to individuals by the General Water Directorate.

Ground water as a habitat may be characterized by geochemistry [120], transmissivity, and biological community. In the Northern Hemisphere, highly transmissive fluvial and post-glacial sediment systems support unique communities of invertebrates that spend part or all of their lives in this dark environment [125]. Although similar geomorphology is present in western Patagonia, we are not aware of any studies on aquifer ecosystems in southern South America.

3.2 Freshwater Biodiversity

The freshwater biodiversity in southwestern Patagonia stands out for its uniqueness despite relatively low richness [70], with Gondwanan elements and endemism at the level of genus and family [134]. This region is a potential refuge for fish, amphibians, crustaceans, and insects, but there is limited knowledge of essential aspects, especially range/distribution. It is interesting to note that this territory is flanked to the north by the Valdivian forests of Chile, and to the south by the Cape Horn Biosphere Reserve [117], both considered to be global hotspots of terrestrial biodiversity.

Several recurrent problems became evident during the preparation of this synthesis of the distribution, habitat, and conservation value of freshwater species: unsystematic and incomplete biodiversity inventories; scarce information on georeferenced observations in the literature; lack of knowledge on total ranges of species distributions or fragmentary distributions, poorly determined habitat for aquatic phases of the life cycle, limited information on migrations, population status, and representation in protected wild areas, and lack of local assessment of threats. At the end of this chapter, we propose some measures to address these deficiencies.

3.2.1 Aquatic Invertebrates

Aquatic invertebrates in southwestern Patagonia have high levels of endemism, for example, for the orders Plecoptera, Ephemeroptera, Trichoptera, Gastropoda, and Crustacea [139]. Although richness appears to be somewhat lower than that found in the Valdivian region (according to Valdovinos [139]), this general pattern may also be a result of the lack of information [34], augmented by logistical obstacles to biological sampling. Our main argument is that southwestern Patagonia conserves a significant percentage of Chilean freshwater macroinvertebrates in a relatively undisturbed, sparsely populated landscape with an important network of nature reserves. The southernmost distribution of several orders and families of aquatic insects is also found in this area [95].

Of the 47 species of dragonflies (Odonata) in Chile, 25 are documented in the study area [27, 68, 96]. There is one endemic family (Neopetalia) and one Gondwanic family (Austrapetaliidae), and seven families have endemic genera. Of the 63 species of stoneflies (Plecoptera) in Chile [143], 54 are in southwestern Patagonia, with one endemic family (Diamphipnoidae), four families with Gondwanic elements, and one threatened species (Andiperla willinki). Thirty-four of the 40 species of Chilean mayflies (Ephemeroptera) have also been recorded, including three families with Gondwanic elements and genus-level endemism. Among crustaceans, fairy shrimp (Anostraca) have four species and one endemic genus [41]. Other crustaceans such as amphipods (Amphipoda: Hyallela spp.), freshwater crabs (Anomura: Aegla spp.), and crayfish (Decapoda: Parastacidae) have species endemic to Patagonia, some in the threatened category (five species of Aegla, two of Parastacidae crayfish).

The “dragon of Patagonia” stonefly (Plecoptera: Andiperla willinki) belongs to an endemic genus and is also an indicator of an extreme ecosystem associated with ice fields (cryophilic species; [75, 128]). A groundwater crustacean documented only from the Simpson River (Crustacea: Stygocaris patagonicus, Noodt, 1963, type locality, Coyhaique) may be indicative of unique ecosystems in the region. Groundwater fauna are otherwise virtually explored in Chile [42], and there are possibly many other unknown and endemic species. Fairy shrimps are often emblematic of salt ponds and semi-permanent pools, which are vulnerable globally [22].

3.2.2 Fish

With a modest list of 19 freshwater fish species (Table 3, Fig. 2), southwestern Patagonia brings together ancient lineages and assemblages with diverse evolutionary and biogeographic origins. On one hand, the distribution of species in the study area includes the southernmost and most differentiated ichthyologic provinces (high endemism) within the Austral Neotropical sub-region: the Chilean Andean-Cuyana and Patagonian provinces [8, 82, 87]. On the other hand, there are two families of wide southern intercontinental distribution and of apparent Gondwanic origin (Galaxiidae and Parcichthyidae; [10, 23]). Most of these species (Table 3, Fig. 2a) are threatened in Chile or Argentina, and a high proportion are endemic to the southern Patagonian biogeographic provinces (84%) [49]. There are endemic genera, including Aplochiton (3 spp.; EN), Hatcheria (H. macraei; VU), and Percichthys (P. trucha; LC).

Table 3 Fish associated with inland waters of southern Chilean Patagonia. Colors correspond to conservation status within the latitudinal distribution (on the right): red (EN), orange (VU), yellow (NT), green (LC) and gray (not determined). Information adapted from the conservation sheets of the Ministry of the Environment; in Spanish Ministerio del Medio Ambiente, MMA (www.mma.gob.cl)
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Fig. 2
2 graphs, 2 photos. A is a bar graph of conservation status by habitat. It plots species versus habitat with river the highest. B plots species versus threats. The bar for habitat loss is the highest. C is a photo of a diver underwater. D is a photo of a catfish.

Distribution of inland water fish by habitat type and conservation category (a) and threat category (b). The photos on the right are from Lake Cochrane in the Baker basin (area of high biodiversity of native fish, see text); (c) large puye Galaxias platei; (d) catfish Hatcheria macraei. Conservation status categories: Endangered (EN), Vulnerable (VU), Near Threatened (NT), Least Concern (LC)

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Patagonian fish are also ecologically and functionally diverse. There are strictly freshwater (e.g. Galaxias platei and P. trucha); diadromous (Aplochiton spp., Galaxias maculatus, and Geotria australis) and estuarine species (Mugil cephalus and Eleginops maclovinus). There are benthivorous (O. hatcheri), planktonic (G. maculatus), piscivorous (A. marinus, G. platei, P. trout) and omnivorous (E. maclovinus) species; although trophic niches are usually variable and change during ontogeny ([37, 101]). There are tiny (<5 cm; B. bullocki, Ch. australe), small (<15 cm; G. maculatus, T. aerolatus) and large fish (>30 cm; G. platei, A. marinus, A. microlepidotus, O. hatcheri, P. trout); introduced and invasive salmonids in the region are the largest and most voracious fish.

Southwestern Patagonia offers excellent opportunities for the conservation of these fish and for improving our knowledge of them. For example, species unknown for the region have recently been documented [8, 137], one of which appears to be restricted to Chilean Patagonia [4]. However, the fauna of significant areas remains unexplored, especially coastal areas, archipelagos, and headwater basins with difficult access.

Phylogeographic studies reveal the resilience of some taxa to prehistoric processes such as the uplift of mountain ranges and glaciations, followed by recolonization associated with climate shifts [152]. Contemporary patterns of genetic diversity and population connectivity, which are key to the design of conservation strategies, are almost unknown, but recent studies reveal a variable degree of isolation and genetic diversity among populations, associated with fluvial connections and disconnections [97], diadromy [43] and presence of invasive salmonids [140, 144]. In the current climate change scenario [85], it is important to safeguard the natural potential for genetic change that could affect the long-term survival of Patagonian fish species [21].

Native fish embody the main biodiversity crisis of freshwater systems, and perhaps of all ecosystems in the region. By virtue of low anthropogenic pressure, southwestern Patagonia is already to some extent a haven for the conservation of a unique ichthyofauna. However, proactive interventions and a better conservation policy are needed. Paradoxically, the main cause of this crisis, the invasive salmonids (Fig. 2b; see Sect. 3.4.) enjoy a level of cultural appreciation and legal protection that hinders the conservation of native fishes.

3.2.3 Amphibians

There are at least 21 species of amphibians in the area covered in this chapter (Table 4), accounting for more than half of those known in the country, many with family and genus endemism. There are four species with extreme endemism, which have been found only in one locality. Lack of knowledge of the geographic range of most amphibians is the greatest impediment to establishing their conservation status; the scarce local information is an obstacle to assessing the viability of populations and their metapopulation dynamics. Aquatic habitat use is often undescribed (Fig. 3b) compared to terrestrial habitat occupied by the adult phase (Fig. 3a).

Table 4 Amphibians associated with inland waters of southern Chilean Patagonia. Consolidated information from the Ministry of the Environment's conservation sheets (www.mma.gob.cl), Chilean conservation status and nomenclature updated based on Correa [38]. Note: official Chilean national biodiversity information is not updated (e.g. at least four potential taxa are not included here: Alsodes coppingeri, A. verrucosus, Ateleognathus salai and Batrachyla fitzroya)
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Fig. 3
3 bar graphs. a. A stacked bar graph of species versus habitat of adult stage. Evergreen has the highest number of species. b. A stacked bar graph of species versus habitat of tadpole stage. Unknown has highest species. c. A bar graph of species versus threats. Habitat loss is the highest threat.

Distribution of amphibians associated with inland waters by habitat type and conservation category of the adult stage (a), tadpole stage (b) and threat category (c). Conservation status categories as in Fig. 2

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The aquatic habitats most frequently mentioned for adult phase are streams and occasionally ponds, however, eggs and tadpoles are not mentioned in most cases. Threats to amphibians are associated with their low population size and distribution, habitat loss (i.e. deforestation), introduction of exotic species (Fig. 3c), and emerging diseases such as chytridiomycosis (Batrachochytrium dendrobatidis), which is causing a devastating pandemic for the world's amphibians [17]. Many amphibian populations probably depend on freshwater systems without fish, especially without introduced salmonids [74, 102, 129]. This suggests the potential value of isolated naturally fishless freshwater systems for freshwater conservation.

3.2.4 Birds

There are 23 species of aquatic birds in conservation categories, although observations are often scarce in the conservation platform of the Ministry of the Environment, and global databases such as “eBird” often have sporadic coverages that concentrates on the coast of Aysén and touristic areas such as Puerto Natales (e.g. Garay et al. [58]). The specific aquatic habitat associations are not well described, and there is little information on migratory patterns [31, 62] or nesting of colonial birds (e.g. yeco, heron, bandurria). There are three principal threats to aquatic birds in Patagonia: (i) predation by exotic species (the most mentioned are mink and salmonids; [54, 64, 72]), (ii) loss of their food source (e.g. piscivorous species, [76]), (iii) habitat loss [83].

The species most at risk of extinction, about which there is somewhat more knowledge, is the Ruddy-headed goose Chloephaga rubidiceps (considered endangered), with losses of >90% of its population in the last century. It was recently estimated that there is a 50% extinction risk within a decade and/or three generations [39]. Although there is relatively comprehensive and coordinated management between Chile and Argentina, predation by introduced species demands permanent active intervention. The work of Cossa et al. [39] may be the best potential example of a recovery plan, with a comprehensive treatment of life cycle, habitat, threats, management, while noting information gaps. Another aquatic bird of conservation importance is the Magellan Plover Pluvianellus socialis, the only migratory and endemic species of the southern zone, but in this case without a designated conservation status or sufficient information or observations for a general conservation assessment.

3.2.5 Mammals

The huillín (Lontra provocax), or river otter, inhabits inland waters with abundant riparian vegetation, from approximately 38°–56° S. During the period 1910–1954 huillín suffered from heavy hunting pressure. There has been limited evidence of recovery, despite large areas of habitat that could be potentially suitable for the huillín, based on the availability of macro-crustaceans in rivers [32]. Genetic studies have confirmed low diversity (genetic bottleneck) in inland freshwater subpopulations, compared to coastal populations south of the Taitao Peninsula [145]. A reduction of up to 50% of the current river and lake population sizes is predicted over the next 30 years for huillín [121]. It is important for the conservation of the huillín that the management and protection of riparian environments be included as part of conservation measures for environmental protection in the region.

3.3 Ecosystem Services of Southwestern Patagonian Freshwater Systems

The benefits that an ecosystem provides to human society, in terms of provisioning, supporting/biodiversity, regulating, or cultural, are collectively referred to as ecosystem services (ES). Since the Millennium Ecosystem Assessment [91], the economic and sociocultural valuation of ES has become prominent in territorial planning and national environmental governance, including Chile. However, despite the great importance of freshwater ES, less than 10% of studies in Chile focus on fresh waters or water resources [14,15,16] and there is no synthesis of ES for Patagonia (although see the terrestrial classification of Martínez-Harms and Gajardo [86]). Valuation of ES in the planning stage of conservation strategies is especially relevant in populated areas, where multiple pressures and interests, and complex balance of provision and demand for ES is intensified. Conversely, it is noted that the main limitation of an ES framework applied to southwestern Patagonia is that there is limited local demand for ES in remote and unpopulated areas, which could affect the sustainability of this approach compared to other conservation measures.

Appreciation of ES is useful in cases where there are complex relationships between multiple ES or conflicts of ES valuation. For example, wild populations of introduced salmonid fish is perceived by many as beneficial, as a food source in rural areas and recreational fishing opportunity that translates into local economic dividends meanwhile others may view salmonids as the most significant threat to native ecosystem integrity [65, 146]. This sort of dichotomy in an ESs context may trigger rather than resolve conflicts, because actions that favor some ES may diminish others. However, it may be possible to find intermediate solutions, such as managing the density of introduced salmonids, which may favor coexistence with native species, simultaneously improving the quality of recreational fishing (robust fish) and the conservation of native biodiversity [36].

Freshwater, terrestrial and marine systems and their ES are interconnected, from the runoff from small headwater basins affected by livestock grazing or forestry practices, to the provision of potable water in lowlands, and transport of materials/nutrients or terrestrial sourced contaminants, to productive marine areas and fjords. Conservation of headwater streams and watersheds without intervention [13] can be justified by ES values related to water quality, carbon sequestration, or biodiversity. While dense forest cover favors carbon sequestration and habitat provision, water storage and supply depend on the geographic context, populations, and productive uses downstream. The hydrological effect of mature forest in terms of water balance vs. vegetation development is, however, complex, conflictive, and often inconclusive (e.g. [53, 55, [61]). Responsible application of ES as an environmental management tool generally involves finding agreements that maximize material, immaterial, and regulatory benefits among different sectors of society, while specifically adding a directional upstream–downstream freshwater context.

These examples illustrate the need to incorporate non-economic criteria in the valuation of ES. It has been recognized recently that certain reductionist implementations of ES translate only into material (e.g. monetary) values, which has motivated the adoption of more holistic and inclusive methods in the United Nations Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) [52]. An initial strategy would be to strengthen scientific understanding of the ES functioning of Patagonian ecosystems, and to identify stakeholders and socioecological systems that benefit from the diverse ES of the region (e.g. [117]).

3.4 Impacts, Stressors, and Threats to Freshwater Ecosystems

Patagonia is an anomaly with regard to the threats to the diversity of freshwater systems. Perhaps only five of the 12 emerging global threats for freshwater systems [111] are relevant to the region: climate change, invasive species, disease, harmful algal blooms (HAB), and hydrological alteration (dams). There is a general lack of information on other threats in the region, such as emerging contaminants, nanomaterials, microplastics, light and noise impacts, salinization, calcium reduction, and accumulative stressors, but we assume that these are minor threats compared to those in other parts of the world. Climate change is among the most disruptive, especially in terms of a threat multiplier. The effect on terrestrial ecosystems in Chilean Patagonia [85] may be distinct from the effects on freshwater systems. Changes in water balance affect river flows and water temperature, water levels in lakes, and connectivity between water bodies. An increase in the frequency and duration of minimum flows is expected, such as all-time minimum recorded flows observed during the 2015–2016 ENSO episode [59]. High extreme events are also expected, due to changes in rainfall intensity and patterns in the rain/snow transition. However hydrologic trends in the region have been subject to very limited analysis, despite the existence of data for many large rivers along the climatic gradient in southwestern Patagonia [59].

Another generalization with respect to climate change is that the effect on freshwater organisms may be more acute than in other ecosystems, mainly due to four factors: (i) warming of water bodies may be disproportionate to increases in air temperature [105]; (ii) stenothermic species (which cannot regulate body temperature through their metabolism) have little capacity to withstand an increase in temperature [33], (iii) dispersal options are more constrained; (iv) many anthropogenic impacts are concentrated near water bodies [151].

Although the thermal niche of most Patagonian species is unknown, some native species (G. platei, P. trout and O. hatcheri) tolerate heat better than salmonids and could benefit from global warming [19, 21]). Regional and global studies have not yet demonstrated a temperature increase in Chile's southern lakes [105, 108]. Possible explanations for this anomaly include the large volume and thermal mass of these lakes, the compensatory effect of accelerated melting of ice and snow and strong winds that deepen the mixing layer.

Invasive species present the most direct and imminent threat and impact to the freshwater ecosystems of Chilean Patagonia. Invasive salmonids such as rainbow trout (Oncorhynchus mykiss), chinook salmon (O. tshawytscha) and brown trout (Salmo trutta) represent major challenges for the conservation of native species in Patagonia [63, 106]. They are also considered to be among the most harmful invasive species worldwide [26].

Ironically, much of the knowledge of freshwater systems in southwestern Patagonia is based on studies of invasive species: salmonids [36, 101, 103]; floodplain plants such as willow and lupine [80, 90, 124]; American beaver as an ecosystem engineer [5,6,7], and the invasive diatom Didymosphenia geminate [24, 113, 111]. Hence, studies of species composition, trophic structure, and functioning of these unique ecosystems have almost always been overwhelmed by the impact of invasive species that are difficult to control and almost impossible to eradicate. There is an urgent need to identify, study, and protect hydrologically isolated areas that can still provide ecological refugia, such as islands and areas upstream of hydrologic barriers such as waterfalls [36, 65, 112].

Exotic pathogens are another type of potentially harmful invasive species. Of greatest current concern is the chytrid fungus B. dendrobatidis (Bd), which causes the panzootic (cf. pandemic) chytridiomycosis of amphibians, in turn is responsible for the largest recorded reduction in biodiversity worldwide attributable to a single pathogen [118]. Chytridiomycosis is considered an emerging epidemic in Chile, it has been documented in a dozen localities between 41°–46° S [17],twelve of the 14 amphibian species evaluated in Chilean Patagonia were Bd+ [17]. Another future threat that could affect humans is giardiasis, caused by a parasite associated with invasive beavers (beaver fever, [50]).

The increase in HABs and their adverse effects on marine ecosystems is discussed by Marquet et al. [85]. A global increase in cyanobacterial blooms in freshwater bodies is expected, due to the combined effect of climate change, land use change, and species introductions [119]. Toxins from new and potentially invasive cyanobacteria species have appeared in Chile in recent years [98]. There are currently no studies or monitoring of this phenomenon in Chilean Patagonia, although there are anecdotal observations of unusual blooms of unknown algae during the El Niño period in 2015–16 (Servicio Nacional de Pesca y Acuicultura, Aysén, personal communication).

Hydroelectric power plants have a great impact on aquatic systems globally, altering the flow regime, reducing sediment and nutrient inputs [126], and acting as barriers to the migration of aquatic species. Water regime alteration due to dams is a gray area of knowledge and uncertain threat in southwestern Patagonia. Proposals for mega hydroelectric projects in Chilean Patagonia have been met by strong social opposition, hydroelectric plants are currently scarce and of low impact. The dam in Los Alerces National Park (Argentina), with a flow regime that alternates with high frequency between minimum and maximum flow, affects the flow of the Futaleufú River in Chile. In this case, the operation of a hydroelectric power plant can have a damaging effect downstream far beyond the footprint of the reservoir.

An impact that is still a mild stressor in southwestern Patagonia should be added to the global list: atmospheric pollution of nitrogen, sulfur, heavy metals, and persistent organic compounds (POPs; [3, 18]). Mercury and POPs have been recorded in Patagonian fish [11, 94]. Although Patagonia is currently one of the areas of the world with the least atmospheric pollution [44, 117], increases in atmospheric nitrogen deposition are predicted, the impact of which can be transformative for low productivity freshwater systems [51, 107].

While emerging threats (sensu Reid et al. [111]) are not as evident in southwestern Patagonia, local impacts, stressors, and threats are evident, with potentially significant cumulative effect over the longer term. Physical habitat alteration, unsustainable water use, pollution, and altered trophic status of water bodies are impacts and threats in Patagonia, as in other regions of the world.

The drastic transformation of the Patagonian landscape during the period of contemporary colonization and fires is discussed in Astorga et al. [13]. Downstream, where land use and impacts have historically been more intense, water bodies have probably borne the brunt of eroded soils, affecting the aquatic food web simultaneously by changing light (primary production) and organic carbon input (allochthonous energy sources). There is a lack of local documentation of these effects, although they are known in freshwater systems worldwide.

Riparian vegetation strips are frequently absent due to extensive cattle and sheep ranching. Valleys and slopes converted to grasslands have a higher risk of sediment entrainment into streams and large rivers. Slopes converted to plantations of exotic species to control erosion have been shown to have very negative effects on the water cycle [76,77,79], although the proportion of the landscape affected by these plantations in the region is small compared to central regions of Chile. Direct impacts include channel modifications for river defenses and aggregate extraction.

These impacts are often located near urban areas or the Southern Highway (in Spanish Carretera Austral). The extraction of sand and gravel in certain reaches used for recreational fishing is currently generating acute conflicts in Coyhaique. Unregulated encroachment on flood plains in urban areas (B. Reid, personal observation) may generate future flood control problems. However, compared to other areas of Chile, current hydroelectric project planning [135, 136] shows a low level of intervention in the morphology of the main rivers of the Patagonian region: Puelo, Yelcho, Palena, Cisnes, Aysén, Baker, and Pascua.

Conflicts over water use and rights are not yet common in Chilean Patagonia as compared to central Chile [46]. Nor is the impact of pollution on watercourses a serious problem [141], except in urban areas, reaches affected by fish farm effluent, and drainage from mine tailings (B. Reid, unpublished data).

Mining exploration has increased in recent years; however, although specific projects have not yet materialized. Organic contaminants are probably of low intensity, considering the current low-intensity state of agriculture and low urban population densities.

Patagonia is at a crucial point regarding freshwater conservation high biodiversity and reference ecosystems coincides with levels of impacts, stressors, and threats that are still slight. Most of the local threats and impacts recorded in fish conservation datasheets (Sect. 3, Fig. 2b) are based on regions with greater urbanization and economic development (33°–41° S) and are not as applicable to the geographic area considered in this chapter. Meanwhile, a significant portion of native amphibians and fish, and the vast majority of aquatic insect species, have ranges that extend to the less intervened areas of southwestern Patagonia.

Local management options are limited with respect to global stressors such as climate change and acute impacts such as invasive species. However, there are many local opportunities exist in terms of habitat protection, best practices, restoration, and mitigation of land use impacts and stressors. Taken together, conservation planning at both scales is relevant to the principle of safe operating space [119]: local actions to offset global stressors should be prioritized.

3.5 Parameters and Tools for the Conservation of Freshwater Ecosystems in Southwestern Patagonia

The conservation of freshwater ecosystems presents special challenges related to connectivity, water flow directionality, snowmelt regime dynamics, and hydrological disturbance. Below, we highlight some of these challenges for species, communities, and ecosystems, and discuss some knowledge gaps and shortcomings, as well as management of the National System of State Wild Protected Areas (SNASPE in Spanish), and watershed management.

3.5.1 Distribution and Conservation of Freshwater Species

There are some key differences in the conservation of freshwater systems with respect to terrestrial systems. In the former, habitat delineation for species in conservation categories can be difficult due to small-scale spatial complexity, hierarchical organization, and directionality in movement and dispersal patterns ([67, 131]). This is even more complicated for the diadromous fish that move between fresh and sea water (e.g. family Galaxiidae, [88]), aquatic insects with aerial/terrestrial dispersal [131], and amphibians whose breeding and rearing sometimes occur in small, isolated water bodies that may be difficult to characterize or delineate. Connectivity between populations is restricted to drainage networks for fluvial species, with corresponding physical barriers such as waterfalls upstream or lakes/estuaries downstream. Knowledge about metapopulations is often essential for conservation purposes. Species-based freshwater conservation approaches require a solid knowledge base of connectivity and integrity of populations at the watershed scale [47, 112, 131]. River connectivity is also related to genetic isolation among populations. Conservation actions should focus on evolutionary blocks or lineages that make up species (evolutionarily significant units, [149]). Several studies on freshwater and diadromous fish [97, 140, 152], amphibians [105], and freshwater crustaceans [150] have revealed significant evolutionary units in southwestern Patagonia, consistent with the degree of population isolation and historical and present fluvial connectivity. Future efforts should target the conservation of more refined evolutionary units than species.

Niche-based models have been used where there is a lack of information on the distribution of native and invasive inland water species (Energy Center, 2016). This tool could be useful as a first filter to assess the future risk of invasive species [30]. However, the bioclimatic variables and land cover attributes used to develop niche models must distinguish between local (i.e. immediate vicinity of a water body) and watershed-level effects, especially where there are strong bioclimatic gradients. Although there are many alternatives for modeling the distribution of aquatic species, the limiting factor in Chilean Patagonia is the lack of direct observations to calibrate and validate these models.

3.5.2 Classification of Communities and Ecosystems

The typology of surface waters is important to regulate, monitor, and manage aquatic ecosystems in a systematic and/or representative manner. The proposed classification of freshwater ecosystems for Chile is based on fish ecoregions crossed with abiotic geomorphological, hydrological, physical, and chemical criteria [56]. However, this classification is especially uncertain for southwestern Patagonia, given the lack of observations of these same parameters of aquatic ecosystems. While we recognize the operational need for a classification, its refinement with field data is indispensable.

Reference systems are complementary to classification systems, also being key to conservation and restoration. This concept includes reference watersheds [47]. Astorga et al. [13] provided a systematic approach to mapping pristine headwater and low-order watersheds in southwestern Patagonia. Most downstream freshwater systems, such as medium and large lakes and rivers, lack a similar analysis of reference condition. For example, Lake Yulton, west of Puerto Aysén, may be among the few large lakes in the world without introduced fish [36], although there is currently no formal recognition of this value.

3.5.3 Site-Based Conservation

Conservation initiatives in parks and reserves need to integrate an aquatic perspective, complementary to the current terrestrial approach. The SNASPE tends to protect high elevation areas such as mountain ranges; however, the most productive freshwater ecosystems are often in low-lying areas excluded from reserves (Fig. 4). Mechanisms must be found to strengthen downstream conservation. The designation of wild and scenic rivers (WSR) [60] was implemented in the USA in the 1960s to offset public incentives for river interventions for hydroelectricity and irrigation, among others. Simultaneously, the WSR designation is complementary to protected areas, aimed especially at river corridors, and may be designated by presidential decree, with the sponsorship of a public agency or local community initiatives.

Fig. 4
3 maps. The first map is of Laguna San Rafael National Park with Nef River, La Colonia River, and Colonia Excluido Lake. Second is Isla Magdalena National Park with Los Maillines River and Pangal River Headwater. Third is Patagonia National Park with Jeinimeni River Headwaters and Chacabuco River Headwaters.

Gaps in river conservation within the current system of protected areas. Three examples are presented: Laguna San Rafael National Park, Magdalena Island National Park, and Jeinimeni sector in Patagonia National Park. Note that SNASPE boundaries (in green) are imprecise and sometimes do not show private land. (e.g. most of the Nef River and Colonia River valleys are private)

Full size image
An aerial view of the zone of a rapid on the Futaleufu River. The water of the river flows speedily and calms at the other end. There is dense vegetation on both sides of the river.

Zone of a rapid on the Futaleufú River, Los Lagos Region. Photograph by Jorge Gerstle

3.5.4 Water Resources

Conservation aspects unique to freshwater ecosystems include water quality, quantity, and hydrologic regime. The Water Code, administered by the General Water Directorate, establishes the national framework regulating water use, water quality standards (Chilean Standard 1333, 409), the National Water Quality Monitoring Network, and the Lake Monitoring Network [46, 141]. Lake monitoring has not been officially implemented in southwestern Patagonia, despite the superabundance of lakes and being a distinct zone in the categories of Fuster (2015), as discussed above. Secondary standards for water quality have also not been developed, except for the Serrano River (Decree 75, 2010). Water quality is generally exceptional, corresponding with lower population density and limited industry in southern Chile [141].

Minimum ecological flows defined in the Water Code (Article 129 bis 1, Law 20.017) are an environmental management tool established to guarantee a minimum flow for maintenance of aquatic ecosystems. Restrictions on the granting of water use rights may preserve up to 20% of the average annual flow as ecological flow, or up to 40% in exceptional cases [114]. However, the application is not systematic and does not adhere to ecological criteria, and most importantly presumes stationarity (e.g. does not consider climate change trends). On the surface, the rivers of western Patagonia with limited existing conflicts over water rights and uses, might offer an exceptional opportunity for establishing ecological flows. However, river flows undergo changes that are difficult to predict in a climate change scenario, which suggests the need for a more conservative criterion. An evaluation of the Murta River sub-basin (Baker River basin; [45]) revealed that a potential ecological flow of 20% or even 40% would still be well below the minimum flows recorded in 25 years of monitoring and would permit the disruption of the natural hydrological regime. The problem is conceptually similar to mitigating the impact of dams and hydroelectric plants by emulating natural flows, aquatic species and their habitats responding to parameters other than averages, such as peak flows, and frequency and duration of floods [109]. While there are currently limited alterations to natural river flow in southwestern Patagonia, the evident impact of hydropeaking caused by an Argentine dam on the Futaleufú River could be minimized by applying similar strategy based on analysis of flow regime.

Another more promising legal instrument given the near reference flow conditions of Chilean Patagonia is the Water Reserve (in Spanish Reserva de Caudal) decrees (Article 147 bis, paragraph 3 of Law No. 20,017 of 2005). This measure allows the setting aside of unoccupied or otherwise unused water rights. The limitation of this tool is that it is used case by case, relies on presidential decree, is reversable and without binding long-term commitments. Conversely, southern Patagonia has the advantage of potential opportunities for application in regions of low anthropogenic intervention, and where unallocated flows are still considerable. In Chilean Patagonia Water Reserves have been applied to the Petrohué, Cochamó, Murta, Figueroa, and Del Oro rivers.

3.5.5 Integrated Watershed Management

Watershed conservation and management is based on a key distinction, which is that the conservation unit does not consist of patches (e.g. vegetation), but rather links terrestrial and aquatic ecosystems through a drainage network. There are few examples in Chile that can serve as a model. One of the main challenges is that differences between stakeholders and the complexity of value conflicts that can be overwhelming, especially for larger watersheds. Thus, for the moment, in southwestern Patagonia it seems more feasible to focus on smaller scales (e.g. rural drinking water systems) or to consider the individual elements that make up good watershed conservation practices—watershed conservation, water management, and water quality of intact headwaters, riparian buffer zones, floodplain conservation, and conservation planning/management of areas of high biodiversity [1, 47].

The importance of conserving the headwaters, the most degradation-sensitive part of drainage networks, is recognized globally [1, 47]. The initiative to map intact watersheds in Patagonia as a basis for freshwater conservation and watershed management is an innovative beginning [13]. Unlike other regions of Chile, in southern Patagonia the headwaters that supply public water provisioning systems are often located in private properties. This presents an opportunity to encourage the proactive development of best practices. For example, riparian vegetation corridors are recommended as a buffer measure in areas dominated by agriculture and forest management. The integrity of the buffer depends on its continuity, while its width may vary [105]. Riparian buffer corridors are included in forest management plans in Chile, however, they are poorly implemented. Headwaters are often in public lands in mountainous regions, but exceptions exist [12]. Downstream, the concept of corridors expands to floodplains, among the world’s most threatened productive ecosystems [130], where large floods are received and buffered, sediment accumulates, and water is stored. In some countries, a public agency analogous to Chile’s National Emergency Office (in Spanish ONEMI), are responsible for regulating activities such as extraction of sand and gravel and urbanization in this zone. In Chile these areas are administered by the Ministry of National Assets (in Spanish MBN, Decreto Supremo 609), but with limited assessment and oversight.

4 Conclusions and Recommendations

A freshwater friendly policy: challenges and recommendations

The extraordinary abundance of water resources in southwestern Patagonia contrasts with the scarcity of knowledge about their corresponding biological diversity, threats and impacts that affect them, and the lack of tools for their sustainable use and conservation. Fortunately, there is still time to move towards a future where freshwater ecosystems are recognized as an essential part of our well-being. This path requires cultural, social, and political changes that are difficult, but possible to achieve in the long term. With this goal in mind, we offer seven recommendations. Some are initiatives that can be implemented in the short term, with limited resources, while others are aimed at the medium and long term because of their greater complexity and need for political and legislative support. These first steps will help in the characterization, assessment, and protection of key freshwater ecosystems:

  • Systematization of biodiversity information. There are huge gaps in the knowledge of freshwater biodiversity and its values, functions and services and current threats. The existing knowledge is mostly separated in different sources or formats, for example scientific versus gray literature, expert or cultural knowledge. We propose synthesis and systematization of biodiversity observations (not just freshwater) followed by the comprehensive and systematic generation of new observations, to facilitate the identification of priority areas, and the design and implementation of monitoring and conservation plans. This progress involves two complementary components: investment in human capital dedicated to the collection of information on biodiversity in the area, and a public platform dedicated to information management. A substantial part of the observations on global biodiversity comes from grey literature, museum collections, and unpublished work of experts. The dedicated work of experts with refined observational skills, taxonomic expertise, and knowledge of natural history would have the added benefit that these experts are also often skilled communicators of biodiversity values. Regarding the second component, we draw attention to the scarcity of geo-referenced information on freshwater species in the national conservation status classification system. Centralized information management is essential and complementary to the work of specialists in taxonomic groups. Finally, it is important to consider that such platforms require human resources for their maintenance, and incentives or mechanisms to solicit contributions from experts.

  • River connectivity inventory. Considering the impact of invasive species on native species in western Patagonia, some key questions arise: where are the refuges for native species? What are the physical barriers to dispersal and invasion? We propose an inventory of barriers, principally natural (waterfalls, steep slopes) and a few anthropogenic (dams) within the river networks of the region, to identify potential refuges for aquatic biodiversity. The mapping we propose may be done based on a digital elevation model, complemented with on-site validation. These maps would facilitate the development of conservation and restoration plans for native fish and systems without fish (as refugia for amphibians and other aquatic fauna; [142]).

  • Recovery plans for the species in greatest danger. A number of freshwater species in southwestern Patagonia are in danger of extinction, including fish of the genus Aplochiton (peladilla), the huillín or river otter, and several species of amphibians whose risk is defined by extremely limited known distribution. Without exception, knowledge of the life history and distribution of these species is fragmentary. Proactive strategies (i.e. recovery plans) for the conservation of native species are just beginning to implemented in Chile, and there are no such initiatives for at-risk freshwater species. Meanwhile, public agencies and existing policies have traditionally favored the propagation and care of introduced salmonids to the detriment of the protection of local biodiversity, including native fish [20]. The lack of knowledge and the use of inappropriate management practices is a dangerous combination that can compromise the future of our natural heritage. Our recommendation is to generate management and conservation plans for threatened species (e.g. [110]) with objectives determined by their population size and distribution, and to involve local stakeholders in monitoring, and adaptive management.

  • Wild and scenic rivers (WSR) model. The WSR model is complementary to the system of public reserves for river sections that are not within the limits of the SNASPE (Fig. 4). This possibility is being discussed preliminarily in Chile, but there are currently no political or legal mechanisms for this region. Regional energy planning [135, 136] and the Reserved Flow concept could serve as base line for WSR proposals.

  • Ecological Flow versus National Water Reserve. In a territory where a substantial part of the flows of large rivers remains in the hands of the Chilean State or effectively unused despite allocation, the legally binding safeguard of Ecological Flows of up to 20–40% of the average annual flow seems arbitrary and insufficient (see above, Sect. 3.5.4). The existing Water Reserve decree or Reserved Flows represents an imperfect option, but the best currently available to guarantee more secure and comprehensive protection, especially combined with Ecological Flow. An analysis based on the Murta River [45], in which the procedure for determining a reserved flow is based on the probability of exceedance, conserving up to 80% of the average flow, would represent an exceptional yet feasible precedent for Chile, considering the opportunities of the region and the needs for ecosystems (i.e. it is complementary to WSR).

  • Binational collaboration in the management of natural resources in Patagonia. Due to the importance of binational watersheds (Chile and Argentina), there is a need to facilitate binational communication and management of water resources in southwestern Patagonia. The first obstacle is political, as any interaction of public services is funneled to the national level. Second, Chile-Argentina binational research in this area is almost non-existent, perhaps because funding for international collaborations typically promotes opportunities with other countries much further away geographically.

  • Environmental standards for territorial planning and development. Potential opportunities exist for mitigating impacts on freshwater systems, such as the Environmental impact Assessment System, regional development plans, and other public subsidies for agricultural or forest production. A major advance would be to have well-defined performance standards for road projects near watercourses. Another example is the incentive programs for agriculture (machinery, fertilizers, etc.) that may result in misapplication and contamination of watercourses over the long term. If such incentives were implemented together with conditional permitting such as buffer zones (vegetation strips) or fencing barriers to protect watercourses, they would be potentially effective in ensuring water quality conservation at the landscape scale.