Conservation of the freshwater fauna of Patagonia: an alert to the urgent need for integrative management and sustainable development

Habit, Evelyn; Cussac, Víctor E.

doi:10.1111/jfb.12882

Cited by 10 publications

(5 citation statements)

References 4 publications

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“…Correa & Hendry, 2012; Habit et al., 2010; Schüttler et al., 2009; Valenzuela et al., 2013), and salmon subsidies could strengthen these negative effects through apparent competition (Sears et al., 2004). The native aquatic fauna in Patagonia is characterised by low species richness but high levels of endemism (Cussac et al., 2016; Valdovinos, 2006), making the increasing abundance of non‐native species a threat to local biodiversity (Habit & Cussac, 2016). At the same time, recreational fisheries in Patagonia are a key contributor to the regional tourism industry, and Chinook have added value to these fisheries.…”

Section: Discussionmentioning

confidence: 99%

Non‐native Chinook salmon add nutrient subsidies and functional novelty to Patagonian streams

et al. 2020

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The impacts of non‐native species are hypothesised to be proportional to the functional distinctiveness of invaders in their invaded ecosystems. Throughout the Patagonia region of southern South America, Chinook salmon (Oncorhynchus tshawytscha) have recently established non‐native populations, and their anadromous, semelparous life cycle could be functionally unique such that marine‐derived nutrients are delivered to streams which have historically lacked such a resource linkage with the ocean. We tested the hypothesis that salmon subsidise biofilm‐associated algae in streams throughout the Aysén province of southern Chile. Using spatial and temporal variation in the presence of salmon among multiple streams and across two spawning seasons, we found strong evidence of salmon‐subsidised algae in three out of four streams examined that have spawning salmon populations. The biofilm of subsidised streams had enriched stable isotopic ratios of nitrogen and carbon, indicating that marine‐derived nutrients were incorporated by biofilms. This nutrient uptake translated into increased algal biomass and percent of total biofilm biomass composed of algae, indicating that the incorporation of marine‐derived nutrients stimulated autotrophic production of biomass. In one stream, the incorporation of marine‐derived nutrients by biofilm occurred in only one of the two studied spawning seasons. Incorporation occurred in a year with low flows of water throughout salmon spawning (4.59 m3/s) and did not occur in a year with much higher flows (41.6 m3/s), suggesting that inter‐annual variation in discharge can mediate the subsidising effect of salmon. These results indicate that Chinook salmon have bridged the historical gap between productive marine ecosystems and nutrient‐poor stream ecosystems in Patagonia. Anadromous salmon can be a significant source of nutrients in nutrient‐limited catchments, and their ongoing expansion in southern South America is likely to entail ecological impacts in stream and riparian food webs.

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Section: Discussionmentioning

confidence: 99%

Non‐native Chinook salmon add nutrient subsidies and functional novelty to Patagonian streams

et al. 2020

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“…Aquaculture, in particular, has introduced several non‐native species (e.g. Britton & Orsi, ; Esselman et al., ; Habit & Cussac, ; Magalhães & Jacobi, ; McKaye et al., ), and together with agriculture, urban and mining development, released heavy loads of pollutants into aquatic systems (e.g. Araújo, Pinto, & Teixeira, ; Barrella & Petrere Jr, ; Wantzen & Mol, ) .…”

Section: A Number Of Threatsmentioning

confidence: 99%

“…During the last half century, human threats transformed unique, pristine or highly diverse regions—the Maya Mountains, Caribbean drainages, Lake Nicaragua, Andean headwaters, Cerrado savannas, Caatinga semi‐arid ecosystems, Atlantic rainforest remnants, Pantanal wetlands, Gran Chaco, Llanos del Orinoco and Moxos, and Chilean Patagonia (e.g. Abilhoa, Braga, Bornatowski, & Vitule, ; Alcorn, Zarzycki, & de la Cruz, ; Cooney & Kwak, ; Esselman et al., ; Habit & Cussac, ; Harer, Torres‐Dowdall, & Meyer, ; Killeen, ; Klink & Machado, ; Leal, Silva, Tabarelli, & Lacher, ). Even the Amazon system, relatively well preserved, is under pressure by urban, hydropower, mining and agribusiness expansion (Castello et al., ; Lees, Peres, Fearnside, Schneider, & Zuanon, ; Winemiller et al., )—and currently by non‐native species (Bittencourt, Silva, Silva, & Tavares‐Dias, ; Padial et al., ; Van Damme et al., ).…”

Section: A Number Of Threatsmentioning

confidence: 99%

Neotropical freshwater fishes imperilled by unsustainable policies

et al. 2017

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Neotropical freshwater fishes are the most diverse on the planet (>5,500 species), although nations in Latin America have been negligent regarding their conservation. National policies have historically encouraged unsustainable practices, and recent decades have witnessed a sharp increase in harmful activities. Our aim with this review was to expose this situation and illustrate how national policies constitute the main threat to freshwater fish biodiversity. We explain that the most devastating, pervasive and systemic threats are rooted in official policies, particularly unsustainable activities (e.g. hydropower, water diversion, mining, aquaculture, agriculture and fishing), poor management/conservation (e.g. fish stocking and passages) and harmful legislation (e.g. poor licensing, non‐native species). We provide a broad portrait of the Neotropical scenario, where unsustainable policies have caused considerable damage to freshwater ecosystems, and focus on major examples from Brazil, where development projects have caused large‐scale losses to fish biodiversity. Such modus operandi of human development is incompatible with the persistence of biodiversity, and no simple solution is available to correct or minimize its effects. The current situation demands a profound behavioural shift towards better practices and policies, or these multiple high‐impact activities will continue eroding freshwater fish biodiversity and impairing essential ecosystem services.

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“…The native aquatic fauna of Patagonia is characterized by low species richness and high levels of endemism, and many of the galaxiid fishes that dominate the native freshwater fish assemblage are imperiled (Habit & Cussac, 2016). The interactions framework proposed here suggests that galaxiids are likely the “loser” of the Chinook salmon invasion of Patagonia given that they are the only taxon with a net negative interaction with Chinook.…”

Section: Discussionmentioning

confidence: 99%

Emergent trophic interactions following the Chinook salmon invasion of Patagonia

et al. 2022

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In their native range, Pacific salmon (Oncorhynchus spp.) have strong interactions with a multitude of species due to the annual pulse of marine-derived nutrients that they deliver to streams and forests when they spawn and die. Over the past few decades, Chinook salmon (Oncorhynchus tshawytscha) has established non-native populations throughout the Patagonia region of southern South America. Here, we provide the first assessment of the pathways through which salmon-derived nutrients enter stream and forest food webs in Patagonia by surveying multiple streams in southern Chile to identify invertebrate and vertebrate consumers of salmon carcasses and summarizing all documented trophic interactions of Chinook salmon in Patagonia. Blowflies (Calliphoridae) were the dominant colonizer of carcasses in the riparian zone, and midge flies (Chironomidae) were the most common invertebrate on submerged carcasses. Camera trap monitoring in the riparian zone revealed consumption of carcasses or carcass-associated invertebrates by the insectivorous passerine bird "chucao" (Scelorchilis rubecula), small rodents (black rat Rattus rattus, house mouse Mus musculus, and/or colilargo Oligoryzomys longicaudatus), the South American fox "culpeo" (Lycalopex culpaeus), and the invasive American mink (Neovison vison). A mink was filmed transferring a carcass from stream to streambank, indicating that vertebrate scavenging likely increases the degree to which marine-derived nutrients enter terrestrial food webs. The native taxa that consume salmon are closely related to species that benefit from salmon consumption in North America, suggesting that the pathways of salmon nutrient incorporation in North American food webs have functionally re-emerged in South America. Similarly, non-native trout (Oncorhynchus mykiss and Salmo trutta) and mink consume salmon in Patagonia, and their eco-evolutionary history of coexistence with salmon could mean that they are preadapted for salmon consumption and could thus be key beneficiaries of this invasion. Expanded monitoring of the Bryan D. Neff and John D. Reynolds are joint senior authors.

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Conservation of the freshwater fauna of Patagonia: an alert to the urgent need for integrative management and sustainable development

Cited by 10 publications

References 4 publications

Non‐native Chinook salmon add nutrient subsidies and functional novelty to Patagonian streams

Non‐native Chinook salmon add nutrient subsidies and functional novelty to Patagonian streams

Neotropical freshwater fishes imperilled by unsustainable policies

Emergent trophic interactions following the Chinook salmon invasion of Patagonia

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