Jerry Arana Maestre

In the Anthropocene, man has imposed his activities above the natural processes of ecosystems. Rivers have undergone major changes associated with urban centers, so monitoring them is important to determine their status and suitability to provide environmental services. Studies applying the community ecology approach, such as energy flow in aquatic macroinvertebrate assemblages, may be appropriate to determine their status and functioning. This study characterized an Andean river that runs across the city of Ayacucho (Peru). Water physicochemical parameters and biotic quality indices were used and compared with the abundance of trophic guild components and functional feeding groups to demonstrate that the latter are at least equally suitable to estimate water quality. The river section studied ranged from 2640 to 2900 m a.s.l. and was monitored in the wet and dry seasons. Six monitoring stations were established according to the extent of the influence of the urban center. Water physicochemical variables and macroinvertebrate abundances were determined. A Surber net was used for multihabitat sampling; macroinvertebrates were identified to genus level (in most cases) and counted to estimate relative abundances. Trophic guilds (detritivore, predator, herbivore) were formed using the genus data from identification according to the information available in Argentina, Colombia, Ecuador, Bolivia, and Peru. Functional feeding groups were set based on the classification of families. The sensitivity of trophic metrics was assessed by relating them to environmental variables and the Andean Biotic Index (ABI), the Biological Monitoring Working Party adapted for Colombia (BMWP/Col.), and the Ephemeroptera, Plecoptera, Trichoptera (EPT) indices. Environmental variables and biotic indices increased significantly in the most impacted stations, where the abundance of most taxa decreased. The components of trophic guilds and functional groups varied, and those feeding on fine particles increased in sites with a higher urban impact. The metrics based on trophic characteristics were highly correlated with the BMWP/Col and ABI indices. Therefore, these indices can be used to estimate river water quality and provide information on its functioning.

Peru is one of the megadiverse countries worldwide, displaying a great diversity of ecosystems due to its tropical location, marine currents, and complex relief, which jointly define environments differentiated by altitude and climatic conditions. The arid and semi-arid ecosystems comprising xeric and Andean shrublands, coastal deserts, and coastal hills, illustrate this diversity of ecosystems; these stretch over 177 358 km², representing 13.8% of the Peruvian territory. Several studies on aquatic macroinvertebrates are being conducted in these ecosystems; although not so numerous yet, have shown a rise in recent years. The objective of this work was to determine the composition and distribution of aquatic macroinvertebrates in the arid and semi-arid ecosystems of Peru. To this end, we conducted a literature survey; the articles and theses found were reviewed and analyzed. The following keywords were used: macroinvertebrates, macrozoobenthos, bioindicators, diversity of aquatic organisms, and water quality; we used the Google Academic search engine, Scopus, Web of Science, ResearchGate and the thesis repositories of Peruvian universities, additionally a thesis from the University of Barcelona. Of a total of 53 sources of information, 38 are theses and 15 are scientific articles conducted from 1992 to 2020, referring to studies conducted at elevations ranging from 0 to 3,831 m asl. Most studies were conducted at the Lima and La Libertad departments, resulting in 20 and 10 publications, respectively. The topics addressed most frequently were bioindication, biodiversity, taxonomy, and distribution. Most theses were carried in the Universidad Nacional de Trujillo and the Universidad Nacional Mayor de San Marcos, with 12 and 10 theses, respectively. The period 2011–2020 records the largest number of publications (40). According to the type of aquatic ecosystem, rivers (38) were the systems most intensively studied, followed by coastal wetlands (14) and lagoons (2); to note, one thesis studied two types of ecosystems. Specimens were collected mainly with the Surber and D nets; as a result, seven phyla, 10 classes, 39 orders, and 118 families were reported. The highest richness of families corresponds to rivers (110), followed by coastal wetlands (57), and lagoons (12). The western hydrographic slope recorded the highest richness at phylum, class, order, and family levels, likely because most investigations were conducted in this slope. On the other hand, the phyla Cnidaria, Nematoda, and Nematomorpha were not recorded in the eastern slope, which showed fewer orders (19) relative to the western slope (39). A similar trend is observed at the family level: of the 118 families recorded, 59 were reported for the eastern slope. The most common families at both sides were Chironomidae, Baetidae, Simuliidae, Elmidae, Hydrophilidae, Libellulidae, Physidae, Dytiscidae, Ceratopogonidae, Coenagrionidae, Hydroptilidae, Hydropsychidae, and Tipulidae. Separately, the most common families in all types of aquatic ecosystems were Chironomidae, Baetidae, and Dytiscidae. It is recommended to further promote studies on macroinvertebrates living in the eastern slope, addressing taxonomic, and ecological topics, as well as broadening the approach to an integral ecosystem view. Finally, the biotic indices should be calibrated and validated for the main hydrographic basins. This work is an initial effort to review, systematize, analyze, and gather the results of studies on aquatic macroinvertebrates in Peru, particularly in arid and semi-arid ecosystems.

Introducción: Los arroyos asociados a bofedales se hallan en ambientes donde las condiciones son extremas con temperaturas muy variables, baja presión atmosférica e intensa radiación solar. Sin embargo, existen ensamblajes de macroinvertebrados asociados a estos ambientes, cuya información es escasa. A escala global y regional, las características de los macroinvertebrados cambian con el aumento de la latitud y altitud (disminución de la riqueza y variación de la composición). A nivel local, también se puede agregar el efecto de las aguas ácidas y de elevada conductividad proveniente de manantiales que se unen a los arroyos, que generan heterogeneidad en la calidad de agua y consecuentemente en las características de los macroinvertebrados. Objetivo: Comparar la diversidad, composición y abundancia de macroinvertebrados y las características fisicoquímicas del agua de arroyos asociados a dos bofedales altoandinos, ubicados en el departamento de Ayacucho, Perú. Metodología: Se estudiaron once estaciones ubicados en arroyos de dos bofedales: 7 en Guitarrachayocc (G) de 43 ha (n = 28) y 4 en Pichccahuasi (P) de 28 ha (n = 8). Se empleó una red de Surber (0.3 mm de malla, área de muestreo de 1 200 cm2), para realizar muestreos mensuales de octubre de 2016 a abril de 2017. Análisis de componentes principales (PCA) y análisis de varianza multivariante no paramétrico (NP-MANOVA) se aplicaron para comparar las características del agua. Además, se utilizó un análisis de coordenadas principales (PCoA) y NP-MANOVA para comparar el ensamblaje. La prueba no paramétrica de Kruskal-Wallis (α = 0.05) se utilizó para comparar las abundancias absolutas de los taxa principales. Resultados: Las características del agua fueron heterogéneas, con pH de 3.2 (± 0.4) a 7.6 (± 0.1), conductividad de 168.9 (± 91) µS/cm a 1 117 (± 159.3) µS/cm; diferencias que fueron significativas (p < 0.05) al comparar las estaciones de muestreo, donde el agua de G6 presenta los mínimos valores de pH y los máximos de conductividad, al igual que cloruros. Se recolectaron un total de 8 126 individuos, distribuidos en 26 taxa de 20 familias, 11 órdenes y cinco clases. Los insectos fueron el grupo más diverso y abundante. A pesar a la cercanía de los arroyos de los bofedales, presentaron diferencias: en G, se registró 25 taxa, con dominancia de Macrelmis sp., Dicrotendipes sp., Claudioperla sp., Meridialaris sp. y en P, 9, con dominancia de Pedrowygomya sp., Hyalella sp. y Dicrotendipes sp. La densidad fue de 475 ind./m2 y de 31 ind./m2 para el bofedal G y P respectivamente, estos valores fueron estadísticamente diferentes (p < 0.05). El PCoA y el PCA confirmados por NP-MANOVA mostraron que G6 es diferente (p < 0.05) dentro de G porque recibe el aporte de agua de un manantial. Conclusiones: La riqueza, composición y densidad de los macroinvertebrados son diferentes en los arroyos según el bofedal al cual se halla asociado. La contribución de los manantiales a los arroyos genera cambios drásticos en la calidad del agua y los macroinvertebrados, determinando la formación de ensamblajes con diferente riqueza y estructura.