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Article

Taxonomic and Functional Responses of Macroinvertebrates to Hydrological Changes and Invasive Plants in an NW Patagonia Riparian Corridor (Argentina)

by
Melina Mauad
1,*,
Julieta Massaferro
1,
Lyudmila Kamburska
2 and
Angela Boggero
2
1
CENAC-APN, CONICET, Fagnano 244, San Carlos de Bariloche 8400, Rio Negro, Argentina
2
CNR-Water Research Institute (IRSA), Corso Tonolli 50, 28922 Verbania Pallanza, Italy
*
Author to whom correspondence should be addressed.
Water 2025, 17(13), 1840; https://doi.org/10.3390/w17131840
Submission received: 19 May 2025 / Revised: 14 June 2025 / Accepted: 16 June 2025 / Published: 20 June 2025
(This article belongs to the Section Biodiversity and Functionality of Aquatic Ecosystems)
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Abstract

This study assessed the taxonomic and functional diversity of aquatic macroinvertebrate communities in Chacabuco stream, a 5500 ha pioneering open conservation ranch of Nahuel Huapi National Park in Argentina, focusing on the effects of seasonal hydrological regimes along a willow-invaded corridor. Sampling was conducted during the spring of 2018 and the summer and spring of 2019, covering high (spring) and low (summer) water levels. Results showed no significant differences in taxonomic diversity between hydrological periods (p = 0.6), and similar taxonomic diversity during the low- and high-water periods of 2019 due to an extreme drought event. Functional diversity varied significantly (p = 0.009) between hydrological periods, and a significant difference in taxonomic diversity between invasive and native plots (p = 0.0001, R = 0.53) was found, while functional diversity revealed less distinction (p = 0.02, R = 0.08). Functional diversity does not follow the same pattern, showing opportunistic taxa such as predators and collectors equally present during both periods, sign of resilience of these FFGs over the others. This pioneering study in the region highlighted the importance of exploring both taxonomic and functional diversity in riparian ecosystems to assess the impact of seasonal hydrological regimes along a willow-invaded corridor and develop a more comprehensive understanding of riparian ecosystem health.

1. Introduction

Riverbanks are considered transition systems between the aquatic and the terrestrial habitats [1]. The structure and typology of these riparian ecosystems are essential components of the river biodiversity and its ecological functioning including provision of food, mitigation of stream water temperature via evapotranspiration and shading, regulation of sediment and nutrient flows, water quality improvement and bank stabilization [2,3]. Modifications to the riparian zone can significantly impact aquatic life because of the interconnection between terrestrial and aquatic ecosystems [4,5]. For instance, changes in the river flow directly affect biotic communities. During periods of summer droughts, high water temperatures and reduced river discharges led to drastic changes in its physical structure, decreasing the capacity of the stream to transport organic matter and causing an increase in detritus coverage and pool availability, thereby enhancing spatial habitat heterogeneity. Even though spatial heterogeneity can provide new habitats for biota, the resulting physicochemical conditions, as demonstrated by previous studies [6,7], can limit the survival of certain species. Bunn et al. [8] observed a similar pattern in Australian streams, where the increasing temperatures and decreasing water flow favored generalist and tolerant species, such as Chironomidae, reducing community diversity. Tomanova et al. [9] found a close relationship between habitat conditions and biological traits of macroinvertebrates, showing the local ability of these organisms to resist floods and droughts depending on the taxa tolerance and shelters availability. Several studies have examined the influence of streamflow on the seasonal variations in macroinvertebrate communities [6,7,9,10]. A study conducted by Blanco in Colombia [11] revealed that extreme climatic events have a significant impact on river macroinvertebrates, resulting in frequent disruption and modifications on species composition. In southern South America, the regional hydrological conditions are strongly influenced by the cycling occurrence of Niño/Niña events, even though there are only a few studies on the influence of climatic variations on freshwater ecosystems [10,11,12,13].
Plant invasions in riparian forests can significantly influence aquatic organisms and, therefore, the functioning of stream ecosystems [3]. Invasive plant species along the riverbanks outcompete with native species, reducing their diversity, changing the frequency and intensity of fires, altering the natural pattern of flooding and sediment transport or reducing the amount of light on the water surface. These changes subsequently affect numerous factors in the aquatic system such as light regime, temperature, oxygen levels, leaf litter input, nutrient cycling, turbidity, soil chemistry, erosion processes and sedimentation [14,15,16], which in turn have direct effect on the benthic communities associated with those habitats by reducing diversity and altering functional groups [17,18]. Particularly, invasive trees, such as willow, have dense canopies that shade out native undergrowth, hence modifying riparian habitats [19] as well as the chemical composition of the soil [15]. This results in strong changes in macroinvertebrate habitat and structure, since invasive riparian vegetation can influence aquatic ecological functions such as moderation of stream temperature through shading, provision of energy from litter fall and by creating buffer zones that mediate infiltration of sediment and nutrients [3].
Macroinvertebrates from riparian systems are crucial indicators of environmental health [20]. They are typically abundant, easy to sample and identify, and have sedentary behavior. Also, they have diverse feeding habits, habitat requirements and life cycles, along with a wide range of tolerance to varied environmental conditions [21]. Macroinvertebrates, besides being excellent indicators of changing environmental conditions, also play an important role in the aquatic food web. They are widely recognized as good bioindicators [22] and have been used to assess stream health across a variety of habitats [23].
The main aim of the study was to compare taxonomic and functional diversity of macroinvertebrates in a Patagonian steppe stream by analyzing the effects of seasonal hydrological regimes along a corridor of willow invasion. In the last decades, steppe rivers of extra-Andean Argentinean Patagonia such as Chacabuco stream have experienced an increasing environmental degradation mainly due to the increasing human activities in the area. This study points out the importance of native riparian environments as buffers in the integrity of the aquatic and terrestrial ecosystems. Therefore, determining their ecological and environmental quality is important for policy conservation and management activities [24,25,26].
We hypothesized that (H1) the seasonal (low vs. high) hydrological regime plays a distinct role in the response of the taxonomic and functional macroinvertebrate composition; (H2) changes in the riparian vegetation due to invasive plant establishment affect the taxonomic and functional composition of macroinvertebrates by modifying local environmental conditions.

2. Materials and Methods

2.1. Study Area

Our study focused on the Estancia Fortin Chacabuco (southwestern part of Neuquen Province; 40°38′59″ S, 70°58′ 0″ W) that showcases The Nature Conservancy’s sustainable grazing efforts in Patagonia to achieve significant conservation objectives. The sampling activities were carried out in the Chacabuco stream, a low order stream of approx. 10 km length, with a permanent water regime (Figure 1). This stream is situated in the transition zone between the semi-arid steppe and the Andean Nothofagus forest in northwest Patagonia. From the source to its mouth, the Chacabuco stream altitude ranges between 850 and 770 m a.s.l., showing along its margins a gradual replacement of native vegetation (xerophytic vegetation interrupted by isolated patches of Nothofagus spp.) with invasive species composed mainly of different species of willow (Salix spp.), reaching ca. 100% cover near its mouth. The presence of willow causes a significant shading along the watercourse that directly affects the aquatic ecosystem biota. Upstream, the substrate type consists mainly of cobbles and pebbles, whereas downstream, it is formed by gravel and sand.
The area is characterized by a cold temperate climate, with a mean annual temperature below 10 °C. The average annual precipitation is 940 mm/year and has a bimodal hydrological regime, with higher precipitation in autumn and winter, which determines peak discharges in autumn–winter and late spring (November–December) due to the snow melting. The summer months (January, February and March), on the contrary, experience the lowest water levels of the year. Figure 2 shows monthly precipitation (mm) in 2018 and 2019, covered in this study.

2.2. Field Sampling

Macroinvertebrate sampling was carried on three occasions: (1) in November 2018 (spring), the highest water level period (HW1), (2) in February 2019 (summer), the lower water level period (LW1), and (3) in November 2019 (HW2). Due to the COVID-19 pandemic, we were unable to carry out the final sampling in February 2020, resulting in only one sample being collected for the low water-level period.
Sampling sites were selected taking into account the riparian vegetation. The upstream area is an open forest characterized by native species (Nothofagus antarctica, Discaria chacaye); the downstream area is mainly represented by several invasive species of willow. Therefore, the sampling points were in (a) native plots (NP1 and NP2), NP1 mainly characterized by runoffs with a streambed bottom of cobbles and pebbles and development of filamentous algae and NP2 having a higher flow velocity and less algae; and (b) invasive plots with willow IP1 and IP2. The first one, IP1, was characterized by pools with sandy bottoms dominated by roots and a noticeable absence of algae and the second, IP2, was a more open area disturbed by cattle and other ungulates using it for crossing or feeding, with abundant filamentous algae. Three replicates were taken in each of the four plots for a total of 36 biological samples. Sampling was carried out along a transect orthogonal to the water flow in all sites to cover all possible microhabitats present in the river.
Macroinvertebrate quantitative sampling was performed using a Surber net of 0.09 m2 surface area and 250 µm mesh size. For each plot, dissolved oxygen (DO), conductivity (CD), temperature (T°C) and pH were measured before macroinvertebrate sampling with a multi-parameter probe (HANNA HI 769828, Hanna Instruments, Woonsocket, RI, USA). Other environmental variables such as substrate type, channel depth and canopy cover (% of river covered by trees) were also recorded at each sampling time.
Average precipitation data from local meteorological stations was provided by Servicio Meteorologico Nacional (https://www.smn.gob.ar/, access date 24 April 2024).

2.3. Taxonomic and Functional Macroinvertebrate Diversity

In the lab, samples were washed and sieved through a set of filters (from 0.25 to 10 mm). Macroinvertebrates were classified to family level using a regional identification key [27].
Functional feeding groups (FFGs) were assigned according to Merrit & Cummins [28], and Miserendino & Pizzolon [29]. Density was obtained by counting individuals of each taxon and expressing the results as the number of individuals per surface area (m2). To analyze the macroinvertebrate assemblage structure, taxa richness (S), Shannon–Weaver diversity index (H) and Jaccard equitability (J) were evaluated for both taxonomic and functional attributes. Also, %EPT (percentage occurrence of Ephemeroptera, Plecoptera and Trichoptera) was estimated. Box plot diagrams for taxonomic and functional metrics were used to evaluate their variation between hydrological periods (low vs. high water levels) and among invasive vs. native plots.

2.4. Statistical Analyses

Non-parametric multivariate analyses were used to evaluate whether and how hydrological variations and plant invasion can affect macroinvertebrate taxonomic and/or functional diversity.
First, a one-way analysis of similarity (ANOSIM) [30] based on Bray–Curtis distance measures using density data was conducted to test for significant differences in taxonomic and functional diversity among hydrological periods and plots. Statistical significance was based on 9999 permutations. Bonferroni corrected p-values were applied when more than two groups were compared to identify significant differences between the groups. Then, non-metric multi-dimensional scaling (NMDS) based on Bray–Curtis distance measure was performed to visualize the distance between species distribution and sites in the multi-dimensional space, with canopy cover and precipitation amount included as environmental variables, expressed in percentage and in mm, respectively. In the NMDS analyses, the log10(x + 1) transformed density to each species of each replicate was included.
ANOSIM and NMDS statistical analyses were carried out using the Paleontological Statistics (PAST) software package Version 4.03 [31]. Box plots were performed using Vegan (2.6-4) and GGplot2 (3.4.4) R packages (R version 4.3.2) [32].

3. Results

3.1. Environmental Variables

Native areas were characterized mainly by riffles/runs and by streambeds composed of cobbles and pebbles with filamentous algae. Non-native areas were characterized by a substrate predominantly composed of sand and gravel, and reduced flow velocity with the presence of numerous pools significantly influenced by a high abundance of willow roots. This area exhibited substantial shading due to the dense canopy cover provided by willows, which reduced sunlight infiltration.
In 2019, Chacabuco stream showed a lower water level (Table 1) and neutral values of pH, but slightly acidic during the low-water period at the IP plot (6.79). Mean water temperature remained above 10 °C in all cases, except for native plots during the high-water period of 2019 (9.57 °C). Mean water conductivity was consistently higher in invasive plots compared to native ones, whereas the opposite trend was observed for dissolved oxygen levels.

3.2. Taxonomic Diversity

From a total of 5683 individuals, 1922 were collected during the high-water period of 2018 (HW1), 1057 during the low-water period of 2019 (LW1) and 2707 during the high-water period of 2019 (HW2) (Table 2). Invasive plots (IP) recorded a total of 3086 ind. and the native plots (NP) 2597 ind.
A total of 31 taxa were identified, with the orders Insecta and Crustacea being the most abundant and diverse groups. Diptera and Trichoptera manifested the highest richness (eight Diptera families and seven Trichoptera families). Mollusca, represented by Sphaeriidae (Bivalvia) and Physidae (Gastropoda) (two families), and Annelida, represented by Lumbriculidae (one family), were the least common taxa. The high-water period (eight families in HW1 and seven families in HW2) consistently displayed higher richness compared to the low-water period (six families). Native and invasive plots exhibited an average of seven families.
During the high-water periods, density was high either in native (1254 ind.m−2 in HW1 and 2537 ind.m−2 in HW2) as well as in one of the invasive plots with Salix spp. (IP1) (2418 ind.m−2 in HW1 and 3137 ind.m−2 in HW2) (Figure 3a). However, in the second invasive plot with Salix spp. (IP2), density was significantly low (2193 and 1815 ind.m−2 in HW1 and HW2, respectively). In the low-water period, density was low in both native (NP) and invasive (IP) plots (289 and 307 ind.m−2, respectively) (Figure 3a). Taxa richness and Shannon diversity (H′) showed higher values during high-water periods (seven taxa and H′ = 1.5 in NP vs. eight taxa and H′ = 1.6 in IP). However, during the high-water period of the second year, macroinvertebrate richness and diversity from one of the invasive plots (IP2) were slightly diverse (6 taxa and H′ = 1.3). On the contrary, the low-water period showed quite low values (4 taxa and H′ = 0.9) (Figure 3b,c).
%EPT showed high values in native plots during 2019: values were around 20% (LW1: NP1 = 20.01% and NP2 = 21%; HW2:NP1 = 17.7% and NP2 = 26.6%) (Figure 3d). However, one of the invasive willow Salix spp. plots showed high percentages during HW1 with values of about IP1 = 13.6% (Figure 3d).
Macroinvertebrate densities showed significant differences between native vs. invasive plots (ANOSIM R = 0.53, p < 0.05) and among hydrological periods (ANOSIM R = 0.17, p < 0.05). The NMDS ordination diagrams applied to sites according to taxa densities showed a strong separation between invasive and native plots supported by environmental variables and %canopy cover (Figure 4a), but not between hydrological periods (Figure 4b). Nevertheless, Bonferroni corrected p-values showed significant differences among hydrological periods except for LW1 and HW2 (p = 0.6) and a positive association between high-water periods and environmental variable precipitation (mm).

3.3. Functional Diversity

Among the 31 taxa recorded, 12 were predators (P), 6 scraper–grazers (Sc), 6 collector–gatherers (CG), 4 collector–filterers (CF) and 3 shredders (Sh) (Table 2).
Predators were in general more abundant in native than in invasive plots (Figure 5a). Throughout the first high-water period, predators showed a mean density value >70 ind.m−2 in native plots while in invasive plots, the values were, in general, <40 ind.m−2. During lower waters, their densities increased considerably, mainly in one native plot (NP1= 167 ind.m−2) and one invasive (IP1 = 93 ind.m−2) (Figure 5a). Over the second high-water period, only one native (NP1) and one invasive plot (IP1) showed higher mean density values (196 ind.m−2 and 274 ind.m−2, respectively) (Figure 5a).
Scrapers showed comparable values during all the studied years in native plots; however, in NP2, there is a marked change in their densities comparing the first and second high-water periods (181 ind.m−2 and 574 ind.m−2, respectively) (Figure 5b). Contrarily, all the invasive plot scrapers showed similar values among hydrological periods even though a slight decrease is evident during the second high-water period (Figure 4b).
Collector–filterers showed high densities in invasive plots, with greater densities in IP2 than IP1 (Figure 5c). However, the highest value was recorded in native plots in 2018 high-water period (NP1 = 874 ind.m−2) (Figure 5c).
Scrapers and collector–filterers showed similar densities during the first high-water period, whereas during the low-water period, scrapers mean that densities remained low, but collector–filterers experienced a significant reduction that persisted during the second high-water period of 2019.
Collector–gatherer densities during the high-water periods were higher in native plots than in invasive ones (over 1500 ind.m−2 and below 800 ind.m−2, respectively). Although during the low-water period, densities were lower than during high-water periods, invasive plots showed higher values (IP1 = 382 ind.m−2, IP2 = 563 ind.m−2) than native ones (NP1 = 267 ind.m−2, NP2 = 389 ind.m−2) (Figure 5d).
Shredders recorded the lowest densities among all FFGs and across all sampling sites. During the high-water period in 2018, their densities were similar across almost all plots, except for one invaded plot which showed no individuals (IP1). During the low-water period, they almost disappeared, with only one native plot (NP1) showing 30 ind.m−2. During the high waters in 2019, their densities increased across all native plots, reaching NP1 = 19 ind.m−2, NP2 = 26 ind.m−2, respectively (Figure 5e).
Functional feeding group densities with ANOSIM showed significant differences between native vs. invasive plots (R = 0.08, p = 0.03) and between high- and low-water periods (R = 0.15, p = 0.0016). NMDS analysis applied to FFG diversity showed no clear relationship between native vs. invasive plots. Nevertheless, invasive plots exhibited a slightly positive association with canopy cover (Figure 6a) but displayed a clear clustering pattern between FFGs and hydrological periods and a clear relation between high-water periods and higher precipitation amounts (Figure 6b). Bonferroni corrected p-values revealed significant differences between hydrological periods, especially between LW1 and HW2 (p = 0.009).

4. Discussion

The greater diversity of macroinvertebrates was found in native plots. These findings are likely linked to sunlight penetration, as native areas are open forest areas, suggesting a favorable habitat diversity for benthic macroinvertebrates that utilize riparian vegetation as food, shelter and oviposition sites [33]. In contrast, the plots invaded by willow showed lower biodiversity, with prevalence of fauna tolerant to anthropogenic disturbances such as changes in stream morphology, increased sedimentation, nutrient overload, microbial contamination and monospecific composition of aquatic biota. Our results further reveal a pronounced separation between native vs. invasive plots in the NMDS ordination, indicating that increased canopy cover, likely attributable to willow presence, is a key environmental factor driving differences in macroinvertebrate assemblage composition. However, when analyzing NMDS ordination with functional diversity, the separation is unclear. Despite a slight relation between canopy cover and invaded plots, the prevalent overlap between these plots indicates a lesser functional differentiation compared to the more pronounced taxonomic one. This may suggest functional resilience despite willow invasion. In these degraded environments, Lumbriculidae emerged as the most abundant taxa, playing a crucial role as a detritus feeder. For instance, one of the invaded plots (IP2) with high densities of tolerant organisms, including Lumbriculidae, Mollusca and Hyalellidae, is a direct crossing point for ungulates and other wildlife. Moreover, this plot was characterized by a low diversity of sensitive taxa.
Trichoptera and Diptera were the most diverse taxa, as it was reported in previous studies in mountain streams from Patagonian Andes [18,34,35]. Particularly, regarding Trichoptera, Hydropsychidae was present at native plots, and in contrast, Leptoceridae and Ecnomidae were present at invasive plots. Diptera was represented primarily by families Chironomidae and Simuliidae. While Simuliidae was highly abundant, particularly in plots with invasive species, Chironomidae showed a more stable distribution. However, Chironomidae exhibited marked seasonal variations, with higher densities during periods of high water, especially in the second year.
Our results are consistent with other studies performed in Australian riparian environments, where it has been suggested that invaded plots with willows support a less diverse aquatic invertebrate fauna than native plots [36]. Our findings are also consistent with observations by Subramanian et al. [37] in India, where insect richness was higher in streams with natural riparian vegetation than in those modified by human activities. A recent study carried out in South American rivers by Fierro et al. [38] revealed that agricultural and non-native forest plantation had the lowest diversity of macroinvertebrate assemblages compared to other land-use types, showing a detrimental effect of these land uses on freshwater ecosystems, and a significant presence of non-insect taxa. Other studies [18,39] carried out in Patagonian streams showed an increase in insects, particularly EPT richness in native riparian areas, which is also consistent with our results.
Among the five identified FFGs, scrapers, predators and collector–gatherers were the most abundant across all assessed plots. In Andean Patagonian rivers, water transparency increased in summer due to low precipitation and riparian erosion [40] and the lack of leaf litter accumulation associated with the deciduous riparian vegetation [41]. In addition, the increased solar incidence during summer enhanced autotrophic production, which benefits herbivores that feed on epilithic algae [42]. This, in turn, supports scrapers such as Baetidae, Leptophlebiidae, Notonemouridae, Sphaeriidae and Physidae. High densities of scrapers were recorded during the high-water period of 2019. It should be noted that 2019 was an extraordinarily dry year with the lowest water levels recorded since 2010 (https://www.argentina.gob.ar/smn, access date 24 April 2024).
Predators, mainly Ceratopogonidae, Dytiscidae and Hydrobiosidae, were dominant during the low-water period and the high-water period in 2019. They appeared mainly in invaded plots. Predators prefer slow flowing or standing waters [7,17,43]; therefore, their presence during the high-water period of 2019 also shows the dry conditions of that year. Collector–gatherers were dominant during the high-water period of 2018, and this could be linked to more unstable conditions during that year. However, in the high-water period 2019, their densities sharply decreased exhibiting patterns similar to those observed during the low-water period of the previous year, which could be likely linked to a decrease in the streamflow velocity from one year to another (Figure 2). Shredders’ highest densities were recorded during the low-water period, particularly in native plots. This finding is consistent with their known feeding strategies closely associated with periphyton and commonly observed in environments characterized by low concentrations of suspended solids [44,45]. However, shredders also showed high densities during the high-water-level period of 2019, evidencing once again the climatic and hydrological similarities of low- and high-water periods of 2019.
Many studies have revealed a positive correlation between the presence of collector–filterers and seston in streams that came from lixiviation in the rainy seasons [18,46]. Our results also agreed with this interpretation, as we observed a high density of collector–filterers during the high-water period 2018. In contrast, densities decreased significantly in 2019, suggesting similar flow rates during the low- and the high-water periods 2019.
In summary, our findings revealed that native plots supported a more taxonomic diversity, characterized by a greater representation of EPT groups; in contrast, invasion plots supported communities with lower taxonomic richness but higher densities, suggesting that communities dominated by a few tolerant species adapted well to altered habitat conditions and resulting in more homogeneous assemblages. This pattern aligns with previous findings in Patagonia freshwater systems, where native vegetation has been associated with higher biodiversity and ecological quality [18,39,40]. In addition, our study showed no significant differences in the taxonomic composition of macroinvertebrates of Chacabuco stream between the low- and high-water periods 2019 (in agreement with the severe drought recorded, (https://www.argentina.gob.ar/smn, access date 24 April 2024) that allowed similar hydrological conditions during low- vs. high-water periods. In contrast, FFG diversity did not follow the same pattern; although water levels influence functional diversity, the functional trait response is not as drastic as their taxonomic diversity response might be. This was evident since organisms belonged to all feeding traits during both low- and high-water periods. Particularly, the high-water period of the second year functionally resembled the low-water period more closely, which could be attributed to the resilience of certain opportunistic functional groups such as collector–gatherers, collector–filters and scrapers that can succeed in different hydrological conditions [47]. Our results emphasize the importance of examining both taxonomic and functional diversity in riparian ecosystems to better understand how local vegetation including invasive plants and environmental conditions influence macroinvertebrate assemblages and densities. In addition, our results highlight the direct influence of seasonal precipitation on the functional diversity of macroinvertebrates, underscoring the role of climate as a crucial driver in structuring macroinvertebrates and, consequently, in determining the ecosystem health.

5. Conclusions

Our study shows that plots with native species always have higher taxonomic diversity during both high- and low-water periods. However, when analyzing the hydrological periods of 2019, the low-water period (LW1) showed significant similarities in terms of taxonomic diversity with the high-water period (HW2). This resemblance could be attributed to the extreme drought event that occurred that year [42,48], also recorded by the meteorological stations near the study site. On the contrary, when we analyzed the functional diversity during low- and high-water periods 2019, macroinvertebrates exhibited different behaviors. Indeed, high densities of opportunistic taxa, such as predators and scrapers, prevailed during both low- and high-water periods 2019 due to favorable conditions.
Our findings highlight the need to investigate both taxonomic and functional diversity within riparian ecosystems. Consequently, we can gain deeper insight into how local vegetation, particularly the presence of invasive plant species, and changing environmental conditions shape macroinvertebrate assemblages and their densities. This comprehensive approach not only enriches our understanding of ecological interactions but also guides conservation strategies designed to protect these vital habitats critical to the National Park Nahuel Huapi.

Author Contributions

Conceptualization, investigation, methodology, writing, original draft preparation, M.M.; conceptualization, supervision, methodology, review and editing J.M.; conceptualization, review and editing L.K. and A.B. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Argentine National Council of Scientific and Technological Research (CONICET, grant number PIP 2017-0669) and conducted at the Estancia Fortín Chacabuco, a 5500 ha private reserve in Patagonia, Argentina. The ranch is managed under a collaborative agreement with The Nature Conservancy, providing a unique opportunity to study the ecological impacts of seasonal hydrological regimes along a willow (invasive in Argentina) corridor within a protected area.

Data Availability Statement

The original contributions in this study are included in the article. Further inquiries can be directed at the corresponding author.

Acknowledgments

The study was carried out within the area of the Estancia Fortin Chacabuco, a private property having an agreement with The Nature Conservancy to allow the development of multidisciplinary research studies. This study was supported by the Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina (PIP-2017-0669).

Conflicts of Interest

The authors declare no conflict of interest.

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Water 17 01840 g001
Figure 1. Map with sampling sites in Chacabuco stream, NW Patagonia, Argentina: Native plot 1 (NP1), Native plot 2 (NP2), Invasive plot 1 (IP1) and Invasive plot 2 (IP2). Dotted arrow shows Salix spp. trend.
Figure 1. Map with sampling sites in Chacabuco stream, NW Patagonia, Argentina: Native plot 1 (NP1), Native plot 2 (NP2), Invasive plot 1 (IP1) and Invasive plot 2 (IP2). Dotted arrow shows Salix spp. trend.
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Figure 2. Monthly precipitation (mm) in 2018 and 2019.
Figure 2. Monthly precipitation (mm) in 2018 and 2019.
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Figure 3. Boxplots of (a) macroinvertebrate density, (b) taxa richness, (c) Shannon diversity and (d) percentage of Ephemeroptera, Plecoptera, Trichoptera (%EPT) during the high-water period of 2018 (HW1), the low-water period of 2019 (LW1) and the high-water period of 2019 (HW2); and between native (light grey) and invasive (dark grey) plots. Center lines of boxplots mark median values of each distribution; no outliers were detected in the analysis.
Figure 3. Boxplots of (a) macroinvertebrate density, (b) taxa richness, (c) Shannon diversity and (d) percentage of Ephemeroptera, Plecoptera, Trichoptera (%EPT) during the high-water period of 2018 (HW1), the low-water period of 2019 (LW1) and the high-water period of 2019 (HW2); and between native (light grey) and invasive (dark grey) plots. Center lines of boxplots mark median values of each distribution; no outliers were detected in the analysis.
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Figure 4. NMDS ordination biplots of macroinvertebrate density (ind.m−2) grouped according to native vs. invasive plots with canopy cover (%canopy in %) (a) and hydrological periods with precipitation (PPT in mm) (b). Stress = 0.21.
Figure 4. NMDS ordination biplots of macroinvertebrate density (ind.m−2) grouped according to native vs. invasive plots with canopy cover (%canopy in %) (a) and hydrological periods with precipitation (PPT in mm) (b). Stress = 0.21.
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Figure 5. Boxplots of (a) density (ind.m−2) of predators, (b) scrapers, (c) collector–filterers, (d) collector–gatherers and (e) shredders during the high-water period of 2018 (HW1), the low-water period of 2019 (LW1) and the high-water period of 2019 (HW2); and between native (light grey) and invasive (dark grey) plots. Center lines of boxplots mark the median values of each distribution. No outliers were detected in the analysis.
Figure 5. Boxplots of (a) density (ind.m−2) of predators, (b) scrapers, (c) collector–filterers, (d) collector–gatherers and (e) shredders during the high-water period of 2018 (HW1), the low-water period of 2019 (LW1) and the high-water period of 2019 (HW2); and between native (light grey) and invasive (dark grey) plots. Center lines of boxplots mark the median values of each distribution. No outliers were detected in the analysis.
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Figure 6. NMDS ordination biplots of FFG densities grouped according to native vs. invasive plots with canopy cover (%canopy in %) (a) and hydrological periods with precipitation (PPT in mm) (b). Stress = 0.23.
Figure 6. NMDS ordination biplots of FFG densities grouped according to native vs. invasive plots with canopy cover (%canopy in %) (a) and hydrological periods with precipitation (PPT in mm) (b). Stress = 0.23.
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Table 1. Physicochemical parameters at two sampling sites (native vs. invasive) in Chacabuco stream, during study period (November 2018—HW1, February 2019—LW1 and November 2019—HW2). Data as mean values ± SD (n = 2). Depth (m), T° = water temperature (°C), Cond = conductivity (mS cm−1), DO = dissolved oxygen (mg−1).
Table 1. Physicochemical parameters at two sampling sites (native vs. invasive) in Chacabuco stream, during study period (November 2018—HW1, February 2019—LW1 and November 2019—HW2). Data as mean values ± SD (n = 2). Depth (m), T° = water temperature (°C), Cond = conductivity (mS cm−1), DO = dissolved oxygen (mg−1).
HW1LW1HW2
NPIPNPIPNPIP
Depth0.50 ± 0.050.43 ± 0.040.38 ± 0.020.24 ± 0.010.26 ± 0.010.34 ± 0.05
pH7.18 ± 0.967.15 ± 0.567.14 ± 0.076.79 ± 0.427.18 ± 0.967.15 ± 0.56
T°13.45 ± 2.0513.25 ± 1.0611.28 ± 2.6711.36 ± 0.289.57 ± 0.4712.21 ± 0.01
Cond89.85 ± 1.63104.10 ± 4.81109.50 ± 14.85125.5 ± 4.9576 ± 2.83112.65 ± 0.50
DO18.05 ± 2.909.05 ± 0.2121.5 ± 0.958.55 ± 0.6412.89 ± 0.4211.01 ± 0.16
Table 2. Mean densities of macroinvertebrates sampled at 4 plots (NP1, NP2, IP1 and IP2) in the 3 hydrological periods analyzed (HW1, LW1 and HW2) in Chacabuco stream in 2018–2019. Functional feeding groups (FFGs) in brackets: Sc, scrapers; P, predators; Sh, shredders; CF, collector–filterers; CG, collector–gatherers.
Table 2. Mean densities of macroinvertebrates sampled at 4 plots (NP1, NP2, IP1 and IP2) in the 3 hydrological periods analyzed (HW1, LW1 and HW2) in Chacabuco stream in 2018–2019. Functional feeding groups (FFGs) in brackets: Sc, scrapers; P, predators; Sh, shredders; CF, collector–filterers; CG, collector–gatherers.
20182019
HW1LW1HW2
TAXANP1NP2IP1IP2NP1NP2IP1IP2NP1NP2IP1IP2
Ephemeroptera
Baetidae (Sc)439235 316815
Leptophlebidae (Sc)154171336818283388
Plecoptera
Gripopterygiidae (Sc)1112719341 11173
Notonemouridae (Sc)20.31 0.3112
Trichoptera
Ecnomidae (P) 0.31 0.3 11 0.30.3
Helicophidae (Sh) 0.31
Hydrobiosidae (P) 0.31 10.30.3
Hydropscychidae (CF)2 12 0.32
Hydroptilidae (Sc) 111
Leptoceridae (Sh)1 0.30.3 1 10.322
Philorheithridae (P) 0.3 1
Diptera
Athericidae (P)1 0.31 10.3
Ceratopogonidae (P)10.341 10.3111
Chironomidae (CG)7444765314263047147152140107
Dolichopodidae (P) 0.3
Empididae (P) 1 0.3
Simulidae (CF)184968 137761
Tabanidae (P) 0.3 0.3 0.3
Tipulidae (P) 0.31
Coleoptera
Dytiscidae (P) 0.3 31 4
Elmidae (Sc)233811275116382
Scirtidae (CG) 0.3 4
Annelida
Lumbriculidae (CG)0.322 62 410.3211
Crustacea
Aeglidae (P)0.32 1 1
Hyalellidae (CG)1 3255 3211 208
Parastacidae (P) 0.3 0.32 0.3
Mollusca
Physidae (Sc) 0.370.31 52
Sphaeriidae (Sc)3 0.3 1 617
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Mauad, M.; Massaferro, J.; Kamburska, L.; Boggero, A. Taxonomic and Functional Responses of Macroinvertebrates to Hydrological Changes and Invasive Plants in an NW Patagonia Riparian Corridor (Argentina). Water 2025, 17, 1840. https://doi.org/10.3390/w17131840

AMA Style

Mauad M, Massaferro J, Kamburska L, Boggero A. Taxonomic and Functional Responses of Macroinvertebrates to Hydrological Changes and Invasive Plants in an NW Patagonia Riparian Corridor (Argentina). Water. 2025; 17(13):1840. https://doi.org/10.3390/w17131840

Chicago/Turabian Style

Mauad, Melina, Julieta Massaferro, Lyudmila Kamburska, and Angela Boggero. 2025. "Taxonomic and Functional Responses of Macroinvertebrates to Hydrological Changes and Invasive Plants in an NW Patagonia Riparian Corridor (Argentina)" Water 17, no. 13: 1840. https://doi.org/10.3390/w17131840

APA Style

Mauad, M., Massaferro, J., Kamburska, L., & Boggero, A. (2025). Taxonomic and Functional Responses of Macroinvertebrates to Hydrological Changes and Invasive Plants in an NW Patagonia Riparian Corridor (Argentina). Water, 17(13), 1840. https://doi.org/10.3390/w17131840

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