The Cautin river is located in the 137 years old Araucania region, Chile (38°S), and is characterized by alterations through human interference due agriculture and towns in its surrounding basin, the presence of salmonids, and by its mixed regime, originated from snow melting in summer and rains in winter. The aim of the present study was to make a review of the inventory and ecological role of the benthic inland water macroinvertebrates of the River Cautin, in order to understand their importance in the ecosystem of the river. The fauna of this river includes a fauna composed of endemic and introduced fish, which has, however, been only poorly studied until now. The literature revealed the presence of abundant populations of Diptera, Trichoptera and Ephemeroptera larval stages, and few crustaceans specifically amphipods and freshwater crabs along the river’s course. Many of these macroinvertebrates are prey for both introduced salmonids and native fishes. Similar results have been reported for other southern Argentinean and Chilean Patagonian rivers.

Daphnia pulex is a freshwater planktonic crustacean, allegedly a cosmopolitan species, which is found in lentic ecosystems. The aim of this study was to conduct a literature review of D. pulex related to its life history and genetic variability, in order to mark a route for future studies. We noted that D. pulex is a model species on which ecological studies have been carried out, as well as molecular studies, in which its molecular diversity has been characterized and such in specimens from different environments: both pristine and under human influence. In particular those studies are highlighted, in which molecular tools have been used to construct phylogenetic trees for study intraspecific differences. Also, in some of these molecular studies, analyses of genetic, inter- and intraspecific diversity have been performed. In addition, analyses of protein expression in D. pulex and related species seem promising in evaluating the detailed role of this species.

Over recent decades, Northern Patagonia in Chile has seen significant growth in agriculture, livestock, forestry, and aquaculture, disrupting lake ecosystems and threatening native species. These environmental changes offer a chance to explore how anthropization impacts zooplankton communities from a molecular–ecological perspective. This study assessed the anthropogenic impact on Daphnia pulex by comparing its proteomes from two lakes: Llanquihue (anthropized) and Icalma (oligotrophic). Results showed substantial differences in protein expression, with 17 proteins upregulated and 181 downregulated in Llanquihue, linked to elevated levels of copper, manganese, dissolved solids, phosphate, and nitrogen. These stressors caused metabolic damage and environmental stress in D. pulex. Our findings highlight the importance of monitoring pollution’s effects on Northern Patagonian ecosystems, especially on keystone species like D. pulex, essential for ecosystem stability. This research provides fresh molecular–ecological insights into pollution’s impacts, a perspective rarely addressed in this region. Understanding these effects is critical for conserving natural resources and offers pathways to study adaptive mechanisms in keystone species facing pollution. This approach also informs strategies for ecosystem management and restoration, addressing both immediate and long-term challenges in Northern Patagonian aquatic environments.

Lately, agriculture, livestock, forestry, and aquaculture activities have been greatly developed in Chilean North Patagonia, negatively impacting the balance of the environmental conditions in lakes and affecting the development and survival of several native species. The aim of this study was to assess the anthropic impact on a zooplankton community in two North Patagonian lakes. We collected samples from four sites belonging to Lake Icalma and Lake Llanquihue, including four replicates per site. Water samples were analyzed for physicochemical characteristics and zooplankton communities. We focused on the presence of Daphnia pulex, a species of zooplanktonic crustacean that performs a key role in capturing energy from primary producers to deliver it to final consumers such as fish. We found that Llanquihue showed higher total phosphorus, nitrogen, copper, iron, manganese, total dissolved solids (TDS), and conductivity (EC) than Icalma. Furthermore, ecological variables were greatly decreased due to total P, total N, manganese, copper, total dissolved solids, and conductivity, which changed the species dominance of the zooplankton community in Llanquihue, indicating some degree of anthropization. This study provides fundamental information on the anthropogenic impact on water quality, as well as on zooplankton diversity, highlighting the importance of monitoring the health of these North Patagonia freshwater ecosystems.