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Geographic location of the study areas and sites (•) where otter scats were collected.
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The diet of southern river otter Lutra provocax Thomas, 1908 was determined from 605 scats collected from four sites in Southern Chile between 1990-1991. Crustacean remains were the most common item found in scats. Crustacean species that were the most common in scats collected from lakes, became less important in the river outlets. Fish remains we...
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... lakes and their main river outlets were chosen for this study ( Fig. 1), representing two of the remaining regions holding southern river otter populations in freshwater habitat in Chile (Medina 1996). Lake Panguipulli (39°43' S, 72°13' W) is drained by the Enco River (140 m a.s.l.) (Fig. 1). The lake is oligotrophic with temperatures above 4°C and a maximum surface temperature of 21"C ( Campos et al. ...
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... lakes and their main river outlets were chosen for this study ( Fig. 1), representing two of the remaining regions holding southern river otter populations in freshwater habitat in Chile (Medina 1996). Lake Panguipulli (39°43' S, 72°13' W) is drained by the Enco River (140 m a.s.l.) (Fig. 1). The lake is oligotrophic with temperatures above 4°C and a maximum surface temperature of 21"C ( Campos et al. 1981). Potential otter prey in Lake Panguipulli and Enco River include the introduced trout Oncorhynchus mykiss (20-210 mm length) and Salmo trutta (42-296 mm); the native fishes Aplochiton zebra (49-159 mm length, average 71 ...
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... Aegla denticulata (8-37 mm cephalotorax length), the crayfish Samas- tacus spinifrons; and the mussels Diplodon chilensis and Chilina spp. (Jara 1977, Campos 1985. The lake shoreline is mainly steep and rocky, 23% of its surface area is of shallow zones (< 30 m deep) (Campos et al. 1981). The Enco River is the only outlet for Lake Panguipulli ( Fig. 1), with a rocky shoreline covered with abundant vegetation (eg, Chusquea quila, Notofagus dombeyi). Lake Todos los Santos (41°08' S, 72°12' W) is drained by the Petrohue River ( Fig. 1) (189 m a.s.l.). The lake is oligotrophic with temperatures above 8°C and a maximum surface temperature of 19°C (Campos et al. 1990). Potential otter ...
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... is mainly steep and rocky, 23% of its surface area is of shallow zones (< 30 m deep) (Campos et al. 1981). The Enco River is the only outlet for Lake Panguipulli ( Fig. 1), with a rocky shoreline covered with abundant vegetation (eg, Chusquea quila, Notofagus dombeyi). Lake Todos los Santos (41°08' S, 72°12' W) is drained by the Petrohue River ( Fig. 1) (189 m a.s.l.). The lake is oligotrophic with temperatures above 8°C and a maximum surface temperature of 19°C (Campos et al. 1990). Potential otter preys are the same as in Lake Panguipulli and the Enco River except that Aegla denticulata is absent (Campos 1985, Jara 1977, C. G. Jara, pers. comm.). The lake shoreline is steep and ...
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... absent (Campos 1985, Jara 1977, C. G. Jara, pers. comm.). The lake shoreline is steep and rocky and is covered with abundant vegetation (in particular Amomyrtus luma, Myrceugenia exsucca, Luma apiculata, Drimys winteri and Nothofagus dombeyi), 8% of the lake surface area is of shallow zones (< 30 m deep) (Campos et al. 1990). The Petrohué River (Fig. 1) is the only outlet for the lake, with a steep, rocky shoreline also covered with abundant vegetation (Nothofagus ...
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... August 1990 to November 1991 monthly patrols were made on foot or by canoe along the shorelines of the study sites. During the initial survey only otter dens and rest-sites were located. Fresh otter scats (one month old or less) were collected monthly in or between dens and rest-sites that were earlier identified (Fig. 1). Scats were dried at 75°C for 24 to 48 hours (Bagenal 1978) and stored in paper bags for later analysis. Prey remains in the dried scats were identified and compared with reference material held at the Instituto de Ecología y Evolución, Universidad Austral de Chile. Fish remains in collected otter scats were identified using scales ...
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Citations
... T. gondii oocysts can be maintained in soil and water, integrating into the trophic web by adhering to aggregates of organic matter (Shapiro et al., 2019). The diet of southern river otters in rivers and lakes is concentrated on macrocrustaceans, fish, and amphibians (Medina, 1997(Medina, , 1998Medina-Vogel & Gonzalez-Lagos, 2008). In marine habitat, the diet is concentrated evenly between fish and crabs (Medina-Vogel et al., 2013). ...
... Since the first nominal description of L. provocax (Thomas, 1908;Carnivora: Mustelidae) from type specimens from Lake Nahuel Huapi in Argentina, this species has been scarcely recorded in nature because its population densities are less than one individual/km 2 (Medina, 1996;Sielfeld & Castilla, 1999). For this reason, most of the ecological knowledge on this species comes from studies that used non-invasive methods-for example, locating latrines, feces, and burrows to analyse their trophic ecology and camera traps to record and infer aspects of their population ecology (Medina, 1998;Medina-Vogel & Gonzalez-Lagos, 2008;Franco et al., 2013;Sepúlveda et al., 2014;Sanino & Meza, 2016). This also explains their scarce records in the largest biodiversity online portal Global Biodiversity Information Facility (GBif). ...
... On the other hand, the high navigability of the study site due to its depth, width, and slow flow speed constitutes an environment of low hydrodynamic energy that favors the establishment of Aegla denticulata denticulata (Parra et al., 2011), the most abundant freshwater crab in the area, while the structure of the swampy forest formed by the pitranto offers an adequate refuge and food environment for the river shrimp (Samastacus spinifrons; Rudolph, 2002). Considering that decapod crustaceans constitute an important fraction of the diet of river otters, including L. provocax (Medina, 1997(Medina, , 1998Medina-Vogel & Gonzalez-Lagos, 2008;Fasola et al., 2009;Rodríguez-Jorquera & Sepúlveda, 2011;Franco et al., 2013;Fuentes & Arriagada, 2023), it is feasible to hypothesize that the environmental conditions of the study area optimally adjust to their trophic and reproductive niche requirements. ...
... Aeglids can be highly susceptible to environmental changes and are, therefore, relevant as indicators of habitat quality (Bond- . These crabs are an important food source for fishes, amphibians, birds (Arenas, 1976), reptiles (Melo, 1990), and mammals (Medina, 1998;Cassini et al., 2009). Aeglids are important components of the trophic web of the ecosystems they inhabit, representing very important links in the transfer of matter and energy (Collins, 2020). ...
We characterized the natural diet and feeding dynamics of Aegla castroSchmitt, 1942 (Aeglidae), an endemic freshwater crab. Research was undertaken on the trophic spectrum of the species by analyzing the stomach contents of individuals collected in a stream in southeastern Brazil, and evaluating the diet through the index of relative importance (IRI). Seasonal and circadian variations in diet composition were analyzed, and the feeding dynamics investigated through repletion index (RI) analysis. We analyzed a total of 240 stomachs and identified 20 main food categories of the diet, which were studied throughout the seasons. Aegla castro maintained a constant RI throughout the year, with a peak of food activity between midnight (00) and 0600. The species was characterized as an omnivorous generalist and opportunist. The high overlay in the diet composition of adults of both sexes and juveniles indicates that they share the same food resources, even though they seem to exploit them in different quantities and frequencies. Future research should focus on the species of Aegla whose diets have not yet been described, and use available data to inform trophic network analyses and models.
... They may also constitute essential components of riverside environments, connecting the aquatic and terrestrial food webs as their predators include amphibians, reptiles and birds (Bond-Buckup & Buckup, 1994;Noro & Buckup, 2002). Likewise, some species constitute 90% of the diet of the Patagonian river otter (Lontra provocax Thomas, 1908), with the distributions of both overlapping (Medina, 1998), and comprise an important food source for trout (Salmo sp.), introduced in Argentina and Chile for commercial and sporting purposes (Jara, Rudolph, & González, 2006). ...
... We found some areas within the ecoregions of priority conservation selected here with threatened species that should be conserved. These areas are located mainly outside the current PA network but are adjacent to them, and an extension of some specific PAs would protect not only the species of Aegla, but also the other freshwater species and components of riverside environments related to them (Bond-Buckup & Buckup, 1994;Jara et al., 2006;Medina, 1998;Noro & Buckup, 2002). The connectivity of the environments would allow the establishment of biological corridors, which are important for the management of hydrographic basins and aquatic/terrestrial natural resources (Feoli Boraschi, 2009). ...
The rapid degradation of freshwater habitats in southern South America may cause the extinction of the endemic species of Aegla , as well as other freshwater species and components of riverside environments related to them. Information on the distribution of species and their conservation status is essential for developing conservation strategies.
The updated distribution of Aegla in its southernmost distribution was analysed in order to prioritize freshwater ecoregions, applying biogeographical, phylogenetic and conservation status and complementarity approaches.
The distributions of the species of Aegla were delineated on maps and plotted against freshwater ecoregions. A data matrix of areas versus species was constructed and a taxon–area cladogram was created. Ecoregions were ranked, based on their species richness and using a complementarity criterion, to create a list of those considered important for conservation. The conservation status of Aegla species was assessed on the basis of the categories and criteria of the International Union for Conservation of Nature (IUCN) to produce a decreasing order of the risk of species extinction. These assessments were combined to define a consensus ranking of the priority areas for conservation.
The areas of maximum species richness and endemicity, and consequently highest priority of conservation, were the Lower Parana and Patagonia ecoregions. The Cuyan Desaguadero and Mar Chiquita Salinas Grandes ecoregions were the areas of second priority, and the Chaco and Lower Uruguay ecoregions were the areas with the third priority for conservation. Ten out of the 20 species analysed fall within the threat categories of the IUCN. Sixty per cent of the species of Aegla analysed have at least one population contained in protected areas.
The results obtained may be used to design strategies for implementing conservation policies on freshwater species, generate biogeographical atlases and contribute to selecting Ramsar sites.
... Aeglids are found exclusively in freshwater habitats and stand out as important links in the food chains for consuming algae, plant remains, microcrustaceans (Bueno and Bond-Buckup 2004) and insect aquatic larvae (Magni and Py-Daniel 1989). Furthermore, they are a significant food source for vertebrates such as fish, amphibians, birds (Arenas 1976) and mammals (Medina 1998;Cassini et al. 2009). ...
Specimens of Aegla castro Schmitt, 1942 were monthly sampled from June 2012 to May 2013 from Couro stream (23°57′15″S 51°06′00″W), located in the Upper Paraná river region, southern Brazil. Population structure, morphometric and functional maturity were analyzed. Allometric growth analysis on chela dimension versus carapace length (CL) was employed to recognize juveniles and adult individuals. Two sequential groups of adult males (morphotypes I and II) were recognized according to the state of development of the pair of claws. The CL where 50% of the population of individuals are adults (CL50) was used to estimate the size at the onset of morphometric maturity. Males attain morphometric maturity at same size class of females (8.0–9.0 mm CL). Males and females are heterochelous and they often show the left chela more developed. The reproductive period was extended from June to September 2012 and April to May 2013 (six months) with record of 22 ovigerous females. The recruitment occurred in the months following the reproductive period, with higher records in October and December 2012. All the information gathered here should be useful to better understand the biology of the species studied.
... A large number of species are restricted to running headwater streams with low temperatures and high oxygen levels, usually located on hillsides or higher altitude regions (Bond-Buckup & Buckup 1994;Teodósio & Masunari 2009;Marchiori et al. 2014). These crustaceans are considered important links in the food chains of limnic environments, acting as predators of aquatic insect larvae (Magni & Py-Daniel 1989) and serving as food for fishes, amphibians, reptiles, birds (Arenas 1976) and mammals (Medina 1998). They may be useful as bioindicators for assessing the quality of the water in which they occur, since they are sensitive to environmental changes (Bond-Buckup & Buckup 1994). ...
This study describes and illustrates the morphology of the first juvenile stage of Aegla castro Schmitt, 1942. Ovigerous females were collected from May to July 2013, in Couro River (Mauá da Serra, Paraná, Brazil). These females were kept individually under controlled feeding, aeration, water temperature and quality and checked daily for hatching of juveniles. The newly-hatched juveniles were fixed in alcohol series and kept in 70% alcohol with glycerin in a 2:1 ratio prior to study under light microscopy. The newly-hatched juvenile of A. castro is the largest among aeglid species whose juveniles have been described. Aegla castro has asynchronous hatching. Some specimens were analyzed using scanning electron microscopy, revealing details of the setal morphology, some cephalothoracic appendages and lineae aeglicae. The number of setae in newly-hatched A. castro is lower than that described for other species, but does not appear to be diagnostic. However, A. castro is the only species described that combines the presence of four plumose setae on the third maxilliped exopod and 63–65 plumose setae on the maxilla exopod.
... Its diet appears to be largely dependent on the availability of prey in the environment ( Pardini 1998, Kasper et al. 2004a, 2008, Gallo-Reynoso et al. 2008, Bastazini et al. 2009, Perini et al. 2009 ). Such dietary flexibility seems to occur in other Lontra and Lutra species as well ( Medina 1998, Ottino and Giller 2004, Preston et al. 2007, Medina-Vogel and Gonzalez-Lagos 2008. ...
... The current knowledge of river otter feeding habits is based primarily on long-term studies of the Euroasiatic otter Lutra lutra ( Foster and Turner 1991, Ottino and Giller 2004, Preston et al. 2007, the North American otter Lontra canadensis ( Cote et al. 2008 ), and two South American species Lontra felina and Lontra provocax that were studied in southern temperate regions ( Medina 1998, Medina-Vogel et al. 2004, Medina-Vogel and Gonzalez-Lagos 2008. The feeding habits of Lontra longicaudis has been studied in freshwater environments in Mexico ( Gallo-Reynoso 1997 , Mac í as-S á nchez and Aranda 1999 , Casariego-Madorell Brought to you by | CAPES Authenticated | vezzosiraul@gmail.com ...
We studied the Neotropical otter (Lontra -longicaudis) seasonal diet variations in the middle Parana River valley, in central-northern Argentina, at the southern limit of its global range. We recorded 745 prey items in 320 scats collected over the course of 1 year in a tributary stream of the Parana River. Fish, crustaceans, mammals, and insects were the most important items in frequency of occurrence among items. Other items, like mollusks, birds, amphibians, and reptilians were presented in low frequency in all seasons. We recorded seasonal variation in the frequency of the principal categories items: fish, mammals, crustaceans, and insects and in reptilian that had low frequency. Although fish were the most common items consumed by the otter, other groups such as crustaceans, mammals, and insects, were also important in the diet of the Neotropical otter throughout the seasons. Mammals and insects showed a higher frequency in the Neotropical otter diet in our study than in Brazil, Mexico, and even northern Argentina. We noted a marked variation throughout the Neotropical region in the niche breadth indices among studies of Neotropical otter's diet. The Shannon H' diversity index showed a higher value in our study than in most of previous diet analyses of this species.
... Extant aeglid crabs are endemic to the southern region of South America, with a single anomuran genus, Aegla, inhabiting inland freshwater streams (Bond-Buckup, 2003). They have been identified as a key links in trophic webs of limnetic environments, serving as food for fish (mainly salmonids) and mammals (Arenas, 1974;Medina, 1998). Aeglids themselves feed on plant debris and insects (especially black fly larvae, which are the aquatic immature stage of the non-aquatic adult form) (Magni and Py-Daniel, 1989;Bueno and Bond-Buckup, 2004;Santos et al., 2008). ...
In Southern Brazil, Aegla parana Schmitt, 1942 is characterized by a broad distribution throughout the Iguaçu River basin, particularly between the southern state of Paraná and the northern state of Santa Catarina, preferentially inhabiting streams with rocky substrates. Although there has been an increase in the number of studies about the population biology of Aeglidae, many aspects about the reproductive biology of A. parana are still unknown. Therefore, the present study aimed to investigate the size at sexual maturity, reproductive
seasonality and recruitment of A. parana from November, 2008 to December, 2009, in a tributary of the Iguaçu River located in União da Vitória, Paraná, Brazil. Basic environmental factors were investigated to determine their influence on the reproductive cycle of this species. Gonadal stages were characterized macroscopically, and the presence or absence of embryos in females (ovigerous females) from monthly samples was recorded. The entire sample was composed of 436 males and 211 females. Although the smallest ovigerous female was 16.2 mm, the average size (carapace length, CL) at sexual maturity (CL50%) was calculated at 17.4 mm. The greatest percentage of females with developed (mature, near spawning) gonads stage was observed from January to June, 2009, while ovigerous females were recorded from April to July, 2009, after which the reproductive period ended. Recruitment occurred from October to December, 2009. The presence of ovigerous females was negatively correlated with temperature (Spearman, p < 0.05). Females carrying embryos were generally collected during periods of lower temperatures, whereas recruits entered the population during periods of higher temperatures, when food for them is more abundant in the region studied.
... Its diet has been studied mainly through the analysis of spraints (Chehébar 1985;Medina 1997). The typical diet of L. provocax primarily consists of crustaceans, followed by fish and other occasional prey such as insects, amphibians, reptiles, birds, and mammals (Medina 1997Medina , 1998Medina-Vogel and Gonzalez-Lagos 2008). The use of non-invasive methods (fecal analysis and food availability) to study carnivore feeding strategies and diet is common practice in ecological studies, and is key to understanding the species role in the ecosystem, potential competition with other species, and impact on prey populations, particularly when direct observations of feeding behavior are often impossible under field conditions (Klare et al. 2011). ...
... Knowledge of L. provocax feeding ecology is critical within a conservation context, particularly in light of the current reduction of their range in Chile (seeSepúlveda et al. 2007). Although there has been an increasing number of studies in the feeding habits of Southern river otters throughout Chile and Argentina (e.g., Medina-Vogel andGonzalez-Lagos 2008;Medina 1997Medina , 1998), it is still not clear what kind of prey items, size, and prey quality are preferred by this species. Also, in order to validate future studies, it is critical to establish their potential role in the ecosystem, potential competition with other species, as well as the real relationship between prey availability, prey presence, and spraints (Franco and Soto-Gamboa 2011). ...
... These sites were regularly surveyed on a monthly basis along a 30-km stretch of the river and associated swamp forest. A preliminary survey was conducted 1 month prior to the first survey in order to find and map otter latrines, to collect records, and to eliminate all possible spraints, smears, and footprints (Medina 1998). Latrines were found at shoreline locations where otters exited the water to defecate, urinate, scent mark, and groom. ...
Non-invasive methodological approaches are highly recommended and commonly used to study the feeding ecology of elusive and threatened mammals. In this study, we use multiple lines of evidence to assess the feeding strategies of the endangered Southern river otter, by determining seasonal prey availability (electrofishing), analysis of undigested prey remains (spraints), and the use of stable isotopes (δ15N and δ13C) in otter spraints (n = 262) and prey in a wetland ecosystem of southern Chile (39°49'S, 73°15'W). Fecal and isotopic analyses suggest that the otter diet is restricted to a few prey items, particularly the less-mobile, bottom-living, and larger prey such as crayfish (Samastacus spinifrons, 86.11 %) and crabs (Aegla spp., 32.45 %), supplemented opportunistically by cyprinids (Cyprinus carpio, 9.55 %) and catfish (Diplomystes camposensis, 5.66 %). The results suggest that the river otter is highly specialized in bottom foraging. Isotopic signatures of food sources and feces revealed a mid-upper trophic position for the Southern river otter, with either higher or lower δ15N values than their potential prey items. δ13C values for river otters were less enriched than their potential food resources. We suggest that due to their narrow trophic niche and possible dependence on only a few food items, this species may be highly vulnerable to the reduction in its prey populations. Finally, maintaining the ecological interactions between Southern river otters and their prey is considered a central priority for the survival of this endangered carnivore mammal.
... stomach content of A. longirostri, from central region of Rio Grande do Sul State. On the other hand, aeglids constitute an important food item in the diet of the trouts Oncorhynchus mykiss (Walbaum, 1792) and Salmo trutta fario Linnaeus, 1758 (Burns 1972, Arenas 1978, Isler 1988, Lara & Moreno 1995 and of the otter Lontra provocax (Thomas, 1908) (Medina 1998). ...
... Aegla laevis laevis Latreille, 1818, Aegla perobaeHebling & Rodrigues, 1977, Aegla platensis Schmitt, 1942, Aegla leptodactyla Buckup & Rossi, 1977, Aegla camargoi Buckup & Rossi, 1977, Aegla lingulata Bond-Buckup & Buckup, 1994 and Aegla longirostriBond-Buckup & Buckup, 1994. They were characterized as opportunistic omnivorous, feeding on diversified food items such periphyton, organic matter coming from allochthonous plants, aquatic invertebrates, fish scales and fine particulate organic matter(Bahamonde & López 1961, Burns 1972, Arenas 1978, Isler 1988, Magni & Py-Daniel 1989, Lara & Moreno 1995, Medina 1998, Bueno & Bond-Buckup 2004, Castro-Souza & Bond-Buckup 2004, Santos et al. 2008.Studies based on stomach contents analysis, using more refined statistical methods have been only published recently.Castro-Souza & Bond-Buckup (2004) evaluated the natural diet of A. camargoi and A. leptodactyla that occur in sympatry at Divisa River, in São José dos Ausentes municipality, Rio Grande do Sul State and Bueno ...
The opportunistic predation on the fishes Astyanax fasciatus and Crenicichla sp. entangled in gill net
by the aeglid crabs Aegla grisella and Aegla singularis was observed in rivers of southern Brazil. These events
occurred in two rivers located at the National Forest of Passo Fundo, in Mato Castelhano municipality, Rio Grande
do Sul State and Tangará municipality, Santa Catarina State. In both places the fish showed similar wound pattern,
with eyes and fins being consumed first. However, predation of the whole body was also recorded, probably
due to the high number of aeglid crabs feeding on the same individual. This record intended to contribute for
understanding the natural diet of these crabs in freshwater environments.
