Dr. Lara-Peña, Carlos

Climate change is reshaping marine ecosystems by altering the timing, intensity, and predictability of key biological processes. In northern Chilean Patagonia, where mussel aquaculture depends on wild seed collection, variability in oceanographic and climatic conditions may affect mussel larval abundance at local scales. Here, we analyze a decade of monthly data on mussel larvae collected at seven sites distributed across contrasting fjord and channel systems. We assess phenological patterns, extreme events, and long-term trends in larval abundance, and evaluate their associations with local hydrography and large-scale climate indices (ENSO, PDO, SAM) and local hydrographic variability. Larval peaks varied in timing and duration across sites, and we identified extreme positive and negative events. Extreme positive larval abundances were concentrated at mid-latitude sites and occurred during strong negative PDO phases, often combined with La Niña or positive SAM. In contrast, decreasing trends were detected at the southernmost sites, while a positive trend emerged at one mid-latitude site. These contrasting patterns suggest that larval dynamics are primarily shaped by large-scale climate forcing, with local hydrographic conditions modulating site-specific responses. These contrasting patterns highlight strong spatial heterogeneity in larval dynamics, suggesting that local hydrographic conditions and geomorphological setting play a key role in modulating the effects of large-scale climate variability. Our results emphasize that larval abundance cannot be generalized across the region and must be interpreted within the context of site-specific processes. Understanding these local dynamics is critical for predicting variability in seed availability and supporting the sustainability of mussel aquaculture under changing environmental conditions.

Small estuaries and coastal lagoons, which are common in Mediterranean climates such as California, Australia and central Chile, are ecologically important systems that can alternate between open (ocean-connected) and closed states depending on the balance between river discharge and wave-driven sediment transport. Under drought conditions, these systems can remain closed for extended periods, which alters hydrodynamic, sedimentary, and ecological processes. This study examines the response of small intermittent estuarine systems to two atmospheric river (AR) events that impacted central Chile in 2023, delivering extreme precipitation, sharp increases in river discharge, and widespread flooding. Using high-resolution satellite imagery and opensource image processing algorithms, we tracked the state of 176 river mouths between 32◦ S and 38◦ S, documenting breaching and subsequent closure in the following months. Our results show that the vast majority of river mouths and coastal lagoons re-established connectivity with the ocean after the ARs, including several that had remained closed for multiple years. Subsequent inlet closures followed a clear north-to-south latitudinal progression, consistent with the transition to wetter climates. Analysis of river discharge and inlet width revealed a strong correlation for Andean-fed rivers with sustained baseflows, while this link was weaker for small coastal rivers that were closed prior to the ARs. The combined analysis of river discharge, wave forcing and inlet state data suggests a nonlinear response in which the timing and sequencing of fluvial and wave forcings govern inlet state transitions. Overall, our findings demonstrate that ARs, which are projected to increase in frequency, can rapidly reset coastal morphology and temporarily restore ocean connectivity in drought-impacted Mediterranean-type coasts.

Coupled fluctuations between ecological and environmental processes — i.e., synchrony — have been documented in marine ecosystems across multiple spatial and temporal scales. To investigate multiscale synchrony, we applied Wavelet Coherence (WC) and Partial Wavelet Coherence (PWC) analyses to disentangle nonstationary associations between local and regional environmental variables that are critical for shellfish aquaculture along the southeastern Pacific. Specifically, we examined and controlled the effects of local associations between sea surface temperature (𝑆𝑆𝑇) and shellfish food supply, represented by normalized fluorescence line height (𝑛𝐹𝐿𝐻), in relation to the regional El Niño–Southern Oscillation (𝐸𝑁𝑆𝑂). Using MODIS-Aqua satellite time series (2003–2022) and the Multivariate ENSO Index (𝑀𝐸𝐼), we assessed temporal changes in the coupling between 𝑆𝑆𝑇 and 𝑛𝐹𝐿𝐻 in two bivalve aquaculture regions: Tongoy Bay (northcentral Chile) and northern Chiloé (southern Chile). Our analyses revealed that 𝑆𝑆𝑇 exhibited a stationary annual cycle explaining over 95% of total variance, while 𝑛𝐹𝐿𝐻 showed a dominant annual mode accounting for more than 60% of variance. However, the second mode of 𝑛𝐹𝐿𝐻 in both Tongoy Bay and northern Chiloé reflected the influence of local drivers — such as freshwater discharge events — that were not synchronized with the dominant pattern. PWC analyses identified significant intra- and interannual synchrony between 𝑛𝐹𝐿𝐻 and 𝐸𝑁𝑆𝑂 within the 1.5–2.5 yr and 3–5 yr bands, after removing the influence of 𝑆𝑆𝑇. These results demonstrate that large-scale climatic forcing modulates local environmental synchrony through differential regional coupling strengths. Consequently, the predictability of environmental conditions relevant to shellfish aquaculture in both regions appears to be strongly constrained by 𝐸𝑁𝑆𝑂-driven variability operating across multiple temporal scales.

Biotic interactions—and predation in particular—are thought to follow a latitudinal gradient, increasing towards the tropics; yet empirical evidence remains contradictory and largely based on studies from the Northern Hemisphere. Moreover, the role of environmental variables shaping latitudinal gradients of predation intensity has seldom been tested. Here, we quantify predation by shell-breaking crabs on modern shells of the marine gastropod Trophon geversianus along a latitudinal gradient (40°–54° S) on the southwestern Atlantic coast. We further evaluate how intrinsic factors (four shell morphometric traits) and extrinsic factors (seven environmental variables and the biogeographic region) jointly influence predation patterns. Fragmentation from crushing predation affected 37% of the shells (544 out of 1480), with the most frequent damage types being major body whorl damage (28%), deep aperture chips (11%) and extensive aperture chips (6%). When analysed by biogeographic province, fragmentation increased significantly towards the south in the Magellan province. Notably, random forest modelling revealed that intrinsic factors—particularly shell size and thickness—were stronger predictors than extrinsic factors in driving latitudinal variability of shell-breaking crab predation. By highlighting the dominant influence of intrinsic factors over extrinsic ones, this study emphasizes the crucial role of species-specific traits in shaping predator–prey interactions across biogeographic regions.

Marine mussels are one of the most important sources of cultivated shellfish worldwide, particularly among middle- and low-income countries where they are a key food source for coastal communities. Climate Change is bound to have a large impact on the distribution of suitable habitats for the mussel species cultivated throughout the world. To examine these impacts on mussel aquaculture and global food security, we evaluated the distribution of suitable current and future habitats for the six more widely cultivated mussel species under a Representative Concentration Pathway 8.5 emission scenario using ecological niche modelling. Occurrence records were obtained from online databases and the literature. The models had a good performance in predicting the current distribution of the six study species. In future scenarios, suitable mussel habitats were projected to shift poleward, with gains at higher latitudes and losses at lower latitudes. By 2050, significant impacts were projected along the Mediterranean coast for Mytilus galloprovincialis, an important mariculture species in Europe, and in Southeast Asia for the tropical green mussel Perna viridis. Overall, our predictions suggested that range shifts could create opportunities to expand mussel farming to higher latitudes, yet loss of suitable habitat in historically productive growing areas could disrupt current mussel aquaculture regions, highlighting the need for immediate action. Therefore, achieving a more nuanced understanding of the spatial changes in the geographic distribution of suitable habitats should be the first step in increasing the adaptive capacity of the mussel aquaculture sector, and ensuring the future supply of this key source of aquafood.

Kelp forest are foundation species that deliver key ecosystem services for coastal habitats. Chile is one of the largest exporters of kelp biomass, which relies on the harvesting of wild populations. The vast and rugged coastline of Chile hinders field-based studies of the seasonal and spatial dynamics of kelp biomass, yet remote sensing approaches can provide an effective tool to study temporal patterns of kelp distribution and biomass. Our study aimed to establish the basic patterns of variation in the surface area and biomass of a Macrocystis pyrifera forest off Concepcion Bay, Central Chile. Using archival data from the Landsat series we constructed a long-term series of annual kelp canopy cover and assessed patterns of interannual, and a seasonal variation with the more recent Sentinel 2 data using Google Earth Engine. We validated satellite observations of the kelp forest in the field by recording local temperature and nutrient concentrations and through a sample of blades and stipes, which we used to estimate whole-individual in situ biomass through allometric relationships. Finally, we related decadal to interannual changes in canopy cover to local and regional drivers using data from public repositories. Our 24-year annual time series revealed large year-to-year variability in kelp forest area that did not show a significant association with different El Niño-Southern Oscillation indices, but the deviance explained increased notably with a 1-year lag. The seasonal time series exhibited clear seasonal patterns with cover peaking during summer. We found a significant influence of local environmental variables such as temperature, wave height, nitrate concentration, and solar radiation on kelp forest area. Furthermore, blade counts appeared as the most reliable metric for estimating M. pyrifera biomass. Interestingly, we found no evidence of temperature or nutrient stress during the summer biomass peak, hence seasonal variation in M. pyrifera abundance appears to be primarily influenced by solar radiation and wave activity in our study population. Our results provide a basis to derive seasonal time series across Chile’s kelp forests and suggest that understanding local stressors is key to ensure harvesting practices that promote the sustainable management of these key habitats. As ongoing climate change and overexploitation threaten kelp forest habitats, remote sensing emerges as a promising tool for the monitoring and management of extensive and remote coastlines.

Coastal wetlands are highly threatened by human activities, leading to water quality degradation and biodiversity loss. This study assessed spatial variation in 27 water quality parameters, sediment organic matter, and macroinvertebrate assemblages across 12 sites in the estuarine Cruces River wetland (CRW Ramsar site, southern Chile) during summer 2019. Our analysis identified three areas of sampling stations in the wetland, categorized by trophic gradient and salinity: freshwater (n = 5), mixed (n = 3), and estuary (n = 4). Freshwater sites were characterized by low salinity, turbidity, and high nitrate concentrations. Estuarine sites were characterized by higher salinities and turbidity and low nitrates and total organic carbon (TOC) concentrations, and mixed sites had low salinities, high turbidities, high TOC, and low nitrates. Throughout the CRW, the richness and densities of different invertebrates were recorded. Freshwater stations had higher species richness, and estuary stations had higher abundance. Macroinvertebrates found in the lower reaches of the CRW included species characteristic of estuarine environments, whereas the upper stations were dominated by invertebrates inhabiting low-salinity environments. According to the ordination plot of distance-based redundancy analysis (dbRDA) and distance-based linear model (DistLM), our results indicate that macroinvertebrate assemblages differ significantly among areas of the CRW, primarily due to physicochemical variables (i.e., salinity, total carbon, and dissolved phosphorus). Total organic matter content in sediments was higher in freshwater sites and lower in estuarine sites. Our findings will be used to monitor the wetland and implement appropriate management measures for human activities, thereby protecting and conserving the estuarine Cruces River Ramsar wetland.

The role of rapid adaptation during species invasions has historically been minimized with the assumption that introductions consist of few colonists and limited genetic diversity. While overwhelming evidence suggests that rapid adaptation is more prevalent than originally assumed, the demographic and adaptive processes underlying successful invasions remain unresolved. Here we leverage a large whole-genome sequence dataset to investigate the relative roles of colonization history and adaptation during the worldwide invasion of the forage crop, Trifolium repens (Fabaceae). We show that introduced populations encompass high levels of genetic variation with little evidence of bottlenecks. Independent colonization histories on different continents are evident from genome-wide population structure. Five haploblocks—large haplotypes with limited recombination—on three chromosomes exist as standing genetic variation within the native and introduced ranges and exhibit strong signatures of parallel climate-associated adaptation across continents. Field experiments in the native and introduced ranges demonstrate that three of the haploblocks strongly affect fitness and exhibit patterns of selection consistent with local adaptation across each range. Our results provide strong evidence that large-effect structural variants contribute substantially to rapid and parallel adaptation of an introduced species throughout the world.

Coastal wetlands are highly threatened by human activities, leading to water quality degradation and biodiversity loss. This study assessed spatial variation in 27 water quality parameters, sediment organic matter, and macroinvertebrate assemblages across 12 sites in the estuarine Cruces River wetland (CRW Ramsar site, southern Chile) during summer 2019. Our analysis identified three areas of sampling stations in the wetland, categorized by trophic gradient and salinity: freshwater (n = 5), mixed (n = 3), and estuary (n = 4). Freshwater sites were characterized by low salinity, turbidity, and high nitrate concentrations. Estuarine sites were characterized by higher salinities and turbidity and low nitrates and total organic carbon (TOC) concentrations, and mixed sites had low salinities, high turbidities, high TOC, and low nitrates. Throughout the CRW, the richness and densities of different invertebrates were recorded. Freshwater stations had higher species richness, and estuary stations had higher abundance. Macroinvertebrates found in the lower reaches of the CRW included species characteristic of estuarine environments, whereas the upper stations were dominated by invertebrates inhabiting low-salinity environments. According to the ordination plot of distance-based redundancy analysis (dbRDA) and distance-based linear model (DistLM), our results indicate that macroinvertebrate assemblages differ significantly among areas of the CRW, primarily due to physicochemical variables (i.e., salinity, total carbon, and dissolved phosphorus). Total organic matter content in sediments was higher in freshwater sites and lower in estuarine sites. Our findings will be used to monitor the wetland and implement appropriate management measures for human activities, thereby protecting and conserving the estuarine Cruces River Ramsar wetland.

Turbidity is associated with the loss of water transparency due to the presence of particles, sediments, suspended solids, and organic or inorganic compounds in the water, of natural or anthropogenic origin. Our study aimed to evaluate the spatio-temporal variability of turbidity from Sentinel-2 (S2) images in the Reloncaví sound and fjord, in Northern Patagonia, Chile, a coastal ecosystem that is intensively used by finfish and shellfish aqua culture. To this end, we downloaded 123 S2 images and assembled a five-year time series (2016–2020) covering five study sites (R1 to R5) located along the axis of the fjord and seaward into the sound. We used Acolite to perform the atmospheric correction and estimate turbidity with two algorithms proposed by Nechad et al. (2009, 2016 Nv09 and Nv16, respectively). When compared to match-up, and in situ measurements, both algorithms had the same performance (R2 = 0.40). The Nv09 algorithm, however, yielded smaller errors than Nv16 (RMSE = 0.66 FNU and RMSE = 0.84 FNU, respectively). Results from true-color imagery and two Nechad algorithms singled an image from the austral autumn of 2019 as the one with the highest turbidity. Similarly, three images from the 2020 austral autumn (May 20, 25, 30) also exhibited high turbidity values. The turbid plumes with the greatest extent occurred in the autumn of 2019 and 2020, coinciding with the most severe storms and runoff events of the year, and the highest turbidity values. Temporal trends in turbidity were not significant at any of the study sites. However, turbidity trends at sites R1 and R2 suggested an increasing trend, while the other sites showed the opposite trend. Site R1 recorded the highest turbidity values, and the lowest values were recorded at R5 in the center of the sound. The month of May was characterized by the highest turbidity values. The application of algorithms from high-resolution satellite images proved to be effective for the estimation and mapping of this water quality parameter in the study area. The use of S2 imagery unraveled a predictable spatial and temporal structure of turbidity patterns in this optically complex aquatic environment. Our results suggest that the availability of in situ data and the continued evaluation of the performance of the Nechad algorithms can yield significant insights into the dynamics and impacts of turbid waters in this important coastal ecosystem.