Small dams also change the benthic macroinvertebrates community in rocky rivers

Abstract

Cite as: Mattos, L. et al. Small dams also change the benthic macroinvertebrates community in rocky rivers. Acta Limnologica Brasiliensia, 2017, vol. 29, e18. Abstract: Aim:Here we analyzed some basic ecological attributes (richness and density) of the benthic community in a stretch of a rocky river under the influence of a small dam of a meter in height, forming a small reservoir of run-of-river type. Methods: Sediment samples were taken with a Petersen collector at three different periods and in three sites: upstream from the dam (site 1), close to the dam (site 2) and downstream from the dam (site 3). Organisms were separated in large groups and Chironomidae genera. Results: The particle size analysis indicated that the sites 1 and 2 are dominated by fine sediments, in contrast to site 3, composed of medium and coarse sediments. A total of 23 taxa of benthic macroinvertebrate groups and 31 genera of Chironomidae were found. Richness and density were different among sampling sites, and for large groups and Chironomidae its attributes increased towards downstream, probably explained by the sediment composition and the originally lotic conditions in site 3, confirmed by all statistical analysis used. In the dam site (2) there was a richness decrease. Non metric multidimensional analysis showed a clear spatial separation of large groups of macroinvertebrates and chironomid genera between sampling sites, indicating that there are typical taxa of each spatial compartment. Canonical correspondence analysis correlated only rubble sediment with the abundance of large groups, and for Chironomidae genera only the granules type was correlationed, with two groups of taxa in the anlysis: one with sites 1 and 2, and other with site 3. Conclusions: Even very small dams in rocky rivers as in the present study alter the environmental variables and ecological attributes of benthic macroinvertebrates.

Impacts of small dams on the phytoplankton and invertebrates in an Amazonian river

“…Increased phytoplankton abundance and changes in composition of groups as occurred in the SHPs of the Juruena River were also observed in other small dams (Table 5). To survive and persist in lotic Lower richness downstream the dam Jesus et al (2004) Decrease in diversity in SHP cascade Lai et al (2022) Altered assemblages close to the dam; increase of invasive species Linares et al (2019) Decrease in density, richness, and diversity downstream the dam, due to drought Martínez et al (2013) Decrease in richness in the dam Mattos et al (2017) Changes in diversity and richness, and decrease in abundance of some functional groups Principe (2010) Abundance, richness, and biotic integrity are lower in the reservoir, with predominance of oligochaetes and chironomids Santucci (2005) Influence on species composition, abundance and functional traits Xiaocheng et al (2008) Decrease in density, richness, diversity and equitability in a nonfunctional knickzone after the SHP construction Ruocco et al (2019) Decrease in abundance, richness, and group diversity up-and downstream the dam This study conditions, phytoplankton populations require certain adaptations.…”

The Effect of a Dam Construction on Subtidal Nematode Communities in the Ba Lai Estuary, Vietnam

“…Dams create water reservoirs upstream from the dam, transform lotic systems into lentic environments, slow down the water flow and cause reduced dissolved oxygen concentrations and a higher deposition of fine sediments in the reservoirs [6][7][8][9]. Consequently, these changes influence the aquatic biodiversity and the local productivity, as well as food web interactions [10,11]. Numerous studies recorded a reduction in abundance and diversity of aquatic communities (e.g., fish, algal, and benthic invertebrates), due to changes in the environment following the construction of a dam.…”

“…Numerous studies recorded a reduction in abundance and diversity of aquatic communities (e.g., fish, algal, and benthic invertebrates), due to changes in the environment following the construction of a dam. [4,10,[12][13][14].…”

“…Also, the Ba Lai estuary itself has started to decrease its water volume, since the reduction in flow can no longer carry away all the alluvium [16]. This process especially changes the benthic environment and its associated biota [5,10], of which free-living nematodes represent one of the most abundant invertebrate groups.…”