Edwin J. Niklitschek

Organic matter (OM), dissolved oxygen (DO), and substrate type (sediment composition and grain size) are fundamental factors influencing benthic macrofauna, shaping taxonomic composition and community structure. The study area encompasses the fjord and channel zone of northwestern Patagonia (41°-46° S) from 2012 to 2017, during which twelve semi-annual sampling campaigns (winter–summer) were conducted, measuring physical variables in the near-bottom water column as well as chemical and biological variables in the sediment.,The characterisation and classification of monitoring sites revealed pronounced spatial and temporal differentiation, with community indicators varying significantly across regions, localities, and seasons. Model fitting showed that sediment properties were the strongest predictors of variability in community indicators, particularly biomass, abundance, and species richness. Salinity emerged as a secondary but significant factor, mainly influencing biomass. In addition, variability among oceanographic zones was identified as a key structuring factor, accounting for a substantial portion of the differences observed in community composition and structure across the fjord–channel system. These findings indicate that different components of the benthic community respond to distinct sets of environmental drivers. These results provide robust empirical evidence of how organic enrichment, sediment characteristics, and oceanographic zonation jointly structure benthic communities in Patagonian fjords, and offer a basis for informing policy and management actions to address the rapid anthropisation of the region, supporting improved evaluation of ecosystem services such as organic carbon, nutrient, and CO2 assimilation and sequestration.

Large-scale climatic variability and emerging diseases can reshape trophic interactions and ecosystem functioning in highly productive upwelling systems. Here, we evaluate how El Niño conditions and the 2022–2023 avian influenza outbreak affected the population trophic niche of the South American sea lion (Otaria byronia) across the central–southern Humboldt Current System. Within an Optimal Foraging Theory framework, we tested whether environmental forcing and changes in prey availability promote trophic niche contraction or expansion. Trophic metrics, including total niche width (TNW), standardized Levins’ index, and taxonomic richness, were estimated from prey remains in scats collected at multiple colonies over several years along the Chilean coast. Local environmental variability associated with El Niño was quantified using daily sea surface temperature anomalies (SST; local Niño index, LIN), together with a categorical index of avian influenza occurrence (IAA) and an index of relative prey abundance (RPA). TNW declined with increasing El Niño intensity, although responses differed among sites and years, indicating spatially heterogeneous climatic effects. In contrast, avian influenza was associated with localized increases in TNW at some colonies, potentially reflecting altered competitive dynamics or shifts in prey exploitation following population impacts. Overall, O. byronia exhibited context-dependent trophic responses to climatic and epidemiological disturbances, underscoring the role of upper trophic predators as sentinels of marine environmental change and trophic restructuring in the Humboldt ecosystem.

More and more data on species traits are being collected and made openly available. Despite these efforts, effective syntheses of trait data to comprehend how species respond to and affect their environment are hampered by inadequate standards for publishing the data and the associated metadata, which limits the interoperability and reuse of data across studies. We have developed ShareTrait ( https://sharetrait.org/ ), a novel initiative that consolidates individual‐level trait data and associated metadata in an interoperable and reusable format, enabling standardised and integrated use. As a proof‐of‐concept, we initially focus on three core traits of ectotherms: metabolic rate, development time and fecundity. These traits, measurable in almost all animals, are fundamental to an organism’s overall fitness. ShareTrait enables researchers to share their (meta)data with the research community. To date, researchers from diverse fields have contributed 28,692 individual‐level data records to ShareTrait. These records originated from 45 datasets and are just the tip of the iceberg of existing data, highlighting the potential of ShareTrait to be a valuable community resource for meta‐analyses and comparative approaches. Future directions of ShareTrait will focus on accumulating more records, expanding to cover more traits, including those measurable at the population level, and partnering with journals in relevant fields (ecology, physiology, evolution) to make sharing standardised trait data part of the standard publication process. We envision ShareTrait, along with its digital infrastructure and comprehensive metadata, to be a catalyst for collating trait data across species. ShareTrait can streamline research efforts, minimise duplication and empower researchers to explore patterns and broader ecological, evolutionary and physiological questions among taxa (e.g. via meta‐analyses and comparative approaches). This way, ShareTrait will unlock new frontiers in trait‐based approaches, enhancing our understanding of species–environment relationships. Read the free Plain Language Summary for this article on the Journal blog.

We used otolith chemistry to test and complement current hypotheses regarding habitat use and connectivity between Dissostichus mawsoni sub-populations in Area 48 of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). Sagittal otoliths from 45 fish sampled near the South Orkney Islands were analysed. Their elemental (Li, Na, Mg, Cr, Mn, Sr, Sn, and Ba relative to Ca) and isotopic (δ¹⁸O and δ¹³C) signatures were examined in both the nuclear and marginal regions, representing juvenile and adult stages. Potential nursery habitats were geo-located by comparing observed and expected δ¹⁸O values. Chemical differences between the nuclear and marginal regions indicated ontogenetic migrations to deeper offshore habitats, suggesting a distinct habitat shift between 11 and 13 years of life. The data supported the existence of two nursery origins contributing to the study area’s population. However, the exact locations of these origins remain unclear and did not provide direct support for the hypotheses currently under consideration by the CCAMLR. Therefore, further assessment of the connectivity between nursery and adult habitats, as well as spawning site fidelity, is necessary before ruling out alternative hypotheses.

We used otolith chemistry tools to test and complement current hypotheses about habitat use and connectivity between Dissostichus mawsoni sub-populations in CCAMLR area 48. Sagittal otoliths from 45 fish sampled around the South Orkney Islands were analysed. Their elemental (Li, Na, Mg, Cr, Mn, Sr, Sn, and Ba, relative to Ca) and isotopic (δ18O and δ13C) signatures were examined in both nuclear and marginal regions, representing juvenile and adult stages, respectively. Potential nursery habitats were geo-located by comparing observed and expected δ18O values. Chemical differences between nuclear and marginal regions were indicative of ontogenetic displacements to deeper offshore habitats, suggesting a discrete habitat shift between 11 and 13 years-old. Data supported the existence of two nursery origins contributing to the study area population. Nonetheless, the location of these origins was unclear and didn not provide any direct support to the hypotheses being currently considered by CCAMLR. Thus, the location and connectivity between nursery and adult habitats, as well as their spawning site fidelity, need to be assessed before disregarding alternative hypotheses07160260Citation: To be added by editorial staff during production. Academic Editor: Firstname Lastname Received: date Revised: date Accepted: date Published: date Copyright: © 2024 by the authors. Submitted for possible open access publication under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).Citation: To be added by editorial staff during production. Academic Editor: Firstname Lastname Received: date Revised: date Accepted: date Published: date Copyright: © 2024 by the authors. Submitted for possible open access publication under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/)..

The blooms of Alexandrium catenella, the main producer of paralytic shellfish toxins worldwide, have become the main threat to coastal activities in Southern Chile, such as artisanal fisheries, aquaculture and public health. Here, we explore retrospective data from an intense Paralytic Shellfish Poisoning outbreak in Southern Chile in Summer–Autumn 2016, identifying environmental drivers, spatiotemporal dynamics, and detoxification rates of the main filter-feeder shellfish resources during an intense A. catenella bloom, which led to the greatest socio-economic impacts in that area. Exponential detoxification models evidenced large differences in detoxification dynamics between the three filter-feeder species surf clam (Ensis macha), giant barnacle (Austromegabalanus psittacus), and red sea squirt (Pyura chilensis). Surf clam showed an initial toxicity (9054 µg STX-eq·100 g⁻¹) around 10-fold higher than the other two species. It exhibited a relatively fast detoxification rate and approached the human safety limit of 80 µg STX-eq·100 g⁻¹ towards the end of the 150 days. Ecological implications and future trends are also discussed. Based on the cell density evolution, data previously gathered on the area, and the biology of this species, we propose that the bloom originated in the coastal area, spreading offshore thanks to the resting cysts formed and transported in the water column.

Quantifying the tropic position (TP) of an animal species is key to understanding its ecosystem function. While both bulk and compound-specific analyses of stable isotopes are widely used for this purpose, few studies have assessed the consistency between and within such approaches. Champsocephalus gunnari is a specialist teleost that predates almost exclusively on Antarctic krill Euphausia superba. This well-known and nearly constant trophic relationship makes C. gunnari particularly suitable for assessing consistency between TP methods under field conditions. In the present work, we produced and compared TP estimates for C. gunnari and its main prey using a standard bulk and two amino acid-specific stable isotope approaches (CSI-AA). One based on the difference between glutamate and phenylalanine (TP_Glx-Phe), and the other on the proline-phenylalanine difference (TP_Pro-Phe). To do that, samples from C. gunnari, E. superba and four other pelagic invertebrate and fish species, all potential prey for C.gunnari, were collected off the South Orkney Islands between January and March 2019, analyzed using standard isotopic ratio mass spectrometry methods and interpreted following a Bayesian approach. Median estimates (CI_95%) for C. gunnari were similar between TP_bulk (3.6; CI_95%: 3.0-4.8) and TP_Glx-Phe(3.4; CI_95%:3.2-3.6), and lower for TP_Pro-Phe (3.1; CI_95%:3.0-3.3). TP differences between C. gunnari and E. superba were 1.4, 1.1 and 1.2, all compatible with expectations from the monospecific diet of this predator (ΔTP=1). While these results suggest greater accuracy for Glx-Phe and Pro-Phe, differences observed between both CSI-AA approaches suggests these methods may require further validation before becoming a standard tool for trophic ecology.

Harmful algal blooms, in particular recurrent blooms of the dinoflagellate Alexandrium catenella, associated with paralytic shellfish poisoning (PSP), frequently limit commercial shellfish harvests, resulting in serious socio-economic consequences. Although the PSP-inducing species that threaten the most vulnerable commercial species of shellfish are very patchy and spatially heterogeneous in their distribution, the spatial and temporal scales of their effects have largely been ignored in monitoring programs and by researchers. In this study, we examined the spatial and temporal dynamics of PSP toxicity in the clam (Ameghinomya antiqua) in two fishing grounds in southern Chile (Ovalada Island and Low Bay). During the summer of 2009, both were affected by an intense toxic bloom of A. catenella (up to 1.1 × 10⁶ cells L⁻¹). Generalized linear models were used to assess the potential influence of different environmental variables on the field detoxification rates of PSP toxins over a period of 12 months. This was achieved using a four parameter exponential decay model to fit and compare field detoxification rates per sampling site. The results show differences in the spatial variability and temporal dynamics of PSP toxicity, given that greater toxicities (+10-fold) and faster detoxification (20% faster) are observed at the Ovalada Island site, the less oceanic zone, and where higher amounts of clam are annually produced. Our observations support the relevance of considering different spatial and temporal scales to obtain more accurate assessments of PSP accumulation and detoxification dynamics and to improve the efficacy of fisheries management after toxic events.

The two mammalian carnivores, puma (Puma concolor) and South American grey fox (Lycalopex griseus) were studied, in a remote area located in the humid temperate forest of the coastal range of southern Chile. A total of six locations were selected in three landscapes: pre-mountain range, mountain range, and coast. The chosen study locations are relevant because they correspond to threatened areas with different levels of human intervention., so they offer the ideal setting for studying how different species of carnivores respond to both human presence and activities. A dataset was collected for 24 months during 2016–2018 through photo-trapping (13 camera traps placed along 50 photo-trap stations). Wes estimated the apparent occurrence and relative abundance index (RAI) of the fauna registered, by means of generalized linear models to contrast those of an apex predator, such as the puma and a sympatric mesopredator, the South American grey fox, across the three landscapes. The ecological variables assessed were the RAI of the other carnivore considered, exotic carnivores such as dogs and cats, human intervention, farmland effect, prey availability, and habitat quality. The primary hypothesis was that the apparent occurrence and RAI of puma and fox would be positively associated with the RAI of prey and livestock and negatively with human intervention. On the other hand, the secondary hypothesis dealt with the interactions between puma and fox faced with different degrees of human intervention. The results showed that the apparent occurrence of the puma was statistically explained by location only, and it was highest at the mountain range. The apparent occurrence of foxes was explained by both puma apparent occurrence and relative integrated anthropization index (INRA), being highest in the pre-mountain range. Concerning the RAI of pumas, high values were yielded by location and fox RAI. For the RAI of foxes, they were location, puma RAI, and INRA. It can be suggested that eucalyptus plantations from the pre-mountain range could offer an adequate habitat for the puma and the fox, but not the coastal range, as the mountain range could be acting as a biological barrier. Due to the nature of the data, it was not possible to detect any relevant effect between the two carnivores’ considered, between their respective preys, or the very abundant presence of dogs.