Natural and Human Influences on Marine Processes in Patagonian Subantarctic Coastal Waters

Abstract

Some of the largest climate changes on Earth are projected for high-latitude polar and subpolar environments in the coming decades (IPCC, 2014). A number of simultaneous socio-environmental perturbations are affecting Patagonia (41-55 • S), a vast and complex ecosystem whose economic and societal well-being depends on coastal resources (∼80% of people live near-shore; the coastal economy provides>40,000 jobs). In this new scenario, overlapping natural variability (interannual-seasonal dynamics) and human-induced environmental changes (global change) are major drivers influencing the marine food web structure and functions. Evidence of large environmental changes has been detected in the Patagonia marine system through (a) regional-scale, climatic-oceanographic coupled anomalous events, (b) interannual hydrological changes (decreasing pattern) in freshwater river inputs (watersheds into fjords), and (c) more frequent coastal and oceanic microbial outbreaks (Harmful Algal Blooms). Those changes have highly uncertain effects for the basic functionalities, structure, and feedback responses of coastal systems and their coupling with hydrological (e.g., river streamflow) or biogeochemical (e.g., biological carbon pump) processes. The northern Patagonian fjords system is hypothesized to act as an indicator of large-scale climate change given strong environmental variability. This, combined with regional climatic-oceanographic events (e.g., El Niño Southern Oscillation, Southern Annular Mode) and effects of local anthropogenic activities (e.g., nutrient fluxes from extensive aquaculture, land change due to forestry) may impact the chemical and physical properties of the surface water, destabilizing biological productivity and chemical coastal processes. The present synthesis, which gives the results of systemicsensitive chemical and biological variables, may be useful to managers and in preventing socio-environmental impacts from increasing natural and anthropogenic phenomena in Chile's southern coastal system.

Evidence of climate-driven changes on atmospheric, hydrological, and oceanographic variables along the Chilean coastal zone

“…2k). These changes, whose mechanisms and future projections are still uncertain, collide with increases in wind, stratification/turbulence, offshore water exportation, and therefore with nutrient levels, levels of acidification, oxygen, and microalgal biomass, including even harmful algal bloom with concomitant consequences in marine fisheries (Aguirre et al 2018;Iriarte 2018;León-Muñoz et al 2018;Soto et al 2019). Management of fisheries and other marine resources in EBUS should thus be improved by better understanding how nutrient enrichment and primary production are related to upwelling processes, and how they are likely to change in the future (Bindoff et al 2019).…”

Marine communities of the newly created Kawésqar National Reserve, Chile: From glaciers to the Pacific Ocean

“…These variations cause highly uncertain trajectories for the basic functionalities, structure, and feedback responses of coastal systems and their coupling with hydrological (e.g., river streamflow) or biogeochemical (e.g., biological carbon pump) processes. This uncertainty raises concern for the persistence of these ecosystems in the future [ 66 ].…”

Depth-Dependent Diversity Patterns of Rocky Subtidal Macrobenthic Communities Along a Temperate Fjord in Northern Chilean Patagonia

“…This fjord harbors a unique subtidal ecosystem, inhabited by speciose communities of deep-water organisms, like corals, that thrive below 20 m depth (e.g., Häussermann and Försterra, 2009;Häussermann et al, 2013). However, rampant anthropogenic direct and indirect pressures, such as the multiple impacts derived from aquaculture activities, industrial and artisanal fisheries, and climate change, pose severe threats to this exceptional and complex ecological system (Försterra et al, 2017;Iriarte, 2018;Soto et al, 2019).…”