Research Outputs
Climate-driven changes in freshwater inputs to a Northern patagonia Fjord and overfishing of wild mussel seed could threaten Chilean mussel farming
Chile is the world’s leading exporter of farmed mussels, with an annual harvest of about 400,000 tonnes; this production is based on the capture of wild seeds, the availability of which may be threatened by climate change and overfishing. Climate change has led to a decrease in annual precipitation, which increases the salinity of the water column and may affect the vertical distribution of mussel populations in fjords. In Reloncaví Fjord, Chile, observed changes in precipitation are reducing freshwater inputs, leading to potential shifts in the habitat and distribution of the economically important Chilean mussel (Mytilus chilensis) and a competing species, Aulacomya atra. This study analyses the vertical dynamics of mussel beds in relation to changing environmental conditions, including freshwater inputs, salinity and hydrological regimes in a fjord exploited for mussel seed collection. The results suggest that decreasing trends in precipitation could lead to increased surface salinity, reducing M. chilensis beds while favouring A. atra, with negative consequences for wild seed collection, thus threatening the Chilean mussel farming industry and predicting socio-economic consequences for small-scale aquaculture. This study also describes the increasing fishing pressure on wild mussel larvae, suggesting joint effects that cannot be disentangled with the information currently available and that represent a key challenge for the design of adaptation measures to climate change. Therefore, this study highlights the need for better monitoring of mussel beds together with seed production and oceanographic conditions, as well as improving aquaculture practices that reduce unnecessary pressure on mussel beds through seed collection in the face of changing environmental conditions.
Influence of the hydrological variability on water quality and benthic macroinvertebrates in a Chilean estuary during a megadrought
The climate crisis has accelerated the frequency and intensity of droughts in the Mediterranean areas, impacting the hydrology and the ecology of their basins. Maule River is the largest watershed in the Chilean Mediterranean Zone. The growing anthropic and environmental pressure has led to changes in the structure and function of its terrestrial ecosystem. However, little is known about its influence on aquatic ecosystems. The effect of the recent extreme drought on the streamflow and its influence on water quality and the benthic macroinvertebrate community structure were evaluated in the Maule River’s lower section. Beyond temporal and spatial fluctuations, healthy and permanently well-oxygenated waters prevailed in the study area. However, during the megadrought period, evidenced by a significant decrease in both precipitation and river streamflow, a greater salt wedge influence was observed, at least, in the last 7 km of the river. Although with certain asynchrony, a change in the structure of the benthic macroinvertebrate community was observed in the upstream stations. This marinization reveals an increase in the domain of marine taxa associated with the Polychaeta group and a clear decrease in typical freshwater Oligochaeta individuals. This modification in the structure of the benthic community is expected to affect the function of this estuarine system. The results presented here highlight the importance of considering the variability associated with biological components for the management of water resources and related ecosystem services, considering that one of the main problems associated with changes in land use and the pressures caused by the climate crisis is the decrease in the quality and availability of water in this and other Mediterranean basins globally.