@misc{10481/92397,
year = {2024},
month = {2},
url = {https://hdl.handle.net/10481/92397},
abstract = {Freshwater megafauna, such as sturgeons, giant catfishes, river dolphins, hippopotami, crocodylians, large turtles, and
giant salamanders, have experienced severe population declines and range contractions worldwide. Although there is
an increasing number of studies investigating the causes of megafauna losses in fresh waters, little attention has been paid
to synthesising the impacts of megafauna on the abiotic environment and other organisms in freshwater ecosystems, and
hence the consequences of losing these species. This limited understanding may impede the development of policies and
actions for their conservation and restoration. In this review, we synthesise how megafauna shape ecological processes in
freshwater ecosystems and discuss their potential for enhancing ecosystem restoration. Through activities such as movement,
burrowing, and dam and nest building, megafauna have a profound influence on the extent of water bodies, flow
dynamics, and the physical structure of shorelines and substrata, increasing habitat heterogeneity. They enhance nutrient
cycling within fresh waters, and cross-ecosystem flows of material, through foraging and reproduction activities.
Freshwater megafauna are highly connected to other freshwater organisms via direct consumption of species at different
trophic levels, indirect trophic cascades, and through their influence on habitat structure. The literature documenting the
ecological impacts of freshwater megafauna is not evenly distributed among species, regions, and types of ecological
impacts, with a lack of quantitative evidence for large fish, crocodylians, and turtles in the Global South and their impacts
on nutrient flows and food-web structure. In addition, population decline, range contraction, and the loss of large individuals
have reduced the extent and magnitude of megafaunal impacts in freshwater ecosystems, rendering a posteriori
evaluation more difficult. We propose that reinstating freshwater megafauna populations holds the potential for restoring
key ecological processes such as disturbances, trophic cascades, and species dispersal, which will, in turn, promote overall
biodiversity and enhance nature’s contributions to people. Challenges for restoration actions include the shifting baseline
syndrome, potential human–megafauna competition for habitats and resources, damage to property, and risk to human
life. The current lack of historical baselines for natural distributions and population sizes of freshwater megafauna, their
life history, trophic interactions with other freshwater species, and interactions with humans necessitates further investigation.
Addressing these knowledge gaps will improve our understanding of the ecological roles of freshwater megafauna
and support their full potential for facilitating the development of effective conservation and restoration strategies to
achieve the coexistence of humans and megafauna.},
organization = {Villum Fonden. Grant Number: 16549},
organization = {Leibniz-Gemeinschaft},
organization = {Danmarks Frie Forskningsfond. Grant Number: 1131-00006B},
organization = {Danmarks Grundforskningsfond. Grant Number: DNRF173},
organization = {Deutscher Akademischer Austauschdienst},
organization = {Chinese Academy of Sciences. Grant Number: E355S122},
publisher = {Wiley},
keywords = {Ecosystem function},
keywords = {Freshwater animals},
keywords = {Ecosystem restoration},
title = {Freshwater megafauna shape ecosystems and facilitate restoration},
doi = {10.1111/brv.13062},
author = {He, Fengzhi and Svenning, Jens-Christian and Chen, Xing and Tockner, Klement and Kuemmerle, Tobias and le Roux, Elizabeth and Moleón Páiz, Marcos and Gessner, Jörn and Jähnig, Sonja C.},
}