Macrofauna community patterns in a Chiloe Island channel used intensely for aquaculture: the ecological status of its benthic environment

Abstract

Background It is known that aquaculture may produce negative environmental effects on marine ecosystems. Southern Chile is one of the most important salmon and mussel-producing areas in the world. Here we assess the ecological status of benthic communities near farming centers in Caucahue Channel, Chiloe, which has been used intensely for salmon and mussel production for 30 years. Methods The macrofauna, sediments and water column were characterized at distances of 5 to 100 m from three salmon and three mussel-producing centers. Information was also obtained from reference sites 500 to 3000 m from these aquaculture farms. The macrofauna and environmental conditions during winter were analyzed using uni- and multivariate analysis and the AZTI Marine Biotic Index (AMBI) as an indicator of benthic community condition. Results (i) There is a high degree of spatial dissimilarity in macrofauna and environmental variables among sampling sites and types of environments (far from or near farming centers) and between the northern and southern areas of the channel; (ii) sediment structure (mean grain size and percentage of total organic matter) correlated with the observed dissimilarities in macrofauna communities; and (iii) the level of perturbation according to AMBI was heterogeneous, with sites in the undisturbed/normal range to moderately disturbed/polluted. Conclusions We found a high spatial dissimilarity in benthic macrofauna and environmental variables among sampling sites, environmental types and between the northern and southern areas of the channel. AMBI and multivariate community-environment analysis are useful tools to define the level of perturbation of a geographic area at different spatial scales, using all the ecological information from each sample and replicates.

Spatial dissimilarity of zooplankton and hydrodynamic conditions in a Patagonian channel used intensely by aquaculture: the influence of a geomorphological constriction

“…These results suggest that even in this short time-sampling period, the measured water column variables (in a multivariate approach) were sufficiently different to produce dissimilar environmental conditions between the two sections of Caucahué Channel. A study carried out in a similar period (June 21-24, 2014) [26] also found differences in environmental variables of the water column (temperature, salinity, dissolved oxygen, pH, among others, in a multivariate approach) between the two sections of the Caucahué Channel. It is important to note that our hydrographic sampling (June 19 and 30, 2014) was done in different transition phases from spring to neap tides.…”

“…There is currently great interest in gathering more information about the ecological and physical-chemical characteristics of receiving ecosystems of salmon and mussel farms in southern Chile, with the aim of minimizing their environmental impacts and thus making them more sustainable [6,43,44]. Despite the global importance of Patagonian ecosystems for salmon and mussel production, there have been few studies on the potential environmental impact of the sum of aquaculture centers located in a geographic unit, and fewer still that include salmon and mussel farms together [26,44]. However, several studies have focused on the local effects (e.g.…”

“…Benthic macrofauna are frequently used to construct indicators for marine ecosystems because these organisms are relatively sedentary, have relatively long life-spans, consist of different species with different tolerances to stress and have an important biogeochemical and ecological role (e.g. [23][24][25][26].). Plankton communities are less used to construct indicators due to their dependence on currents, high degree of spatial heterogeneity, high temporal variability and difficulty in finding recognizable patterns [27][28][29].…”

Flexibility in the face of climate change? A rapid and dramatic shift toward later spring migration in Hudsonian Godwits (Limosa haemastica)

“…In southern Chile, the burgeoning aquaculture industry has changed many coastal areas, making coastal habitats increasingly dynamic. For instance, godwits, as well as other shorebirds, exclusively forage in the supratidal mudflats located in coastal bays that are also used for the cultivation and harvesting of fish, shellfish, and algae [42][43][44] . The effects of such practices on shorebird communities are complex.…”

Climate change, marine resources and a small Chilean community: making the connections

“…Effects of aquaculture in the area were excluded, as the chosen model location is in the central gulf. Hernández-Miranda et al (2021) show local impact of aquaculture on environmental quality, with the highest impacts directly next to the coastal salmon farms. Bravo et al (2020) show significant regional downstream connectivity between aquaculture farms in the Inner Sea of Chiloé.…”