Lower Trophic Levels Research Articles

Rapid Zooplankton Assessment: Evaluating a Tool for Ecosystem‐Based Fisheries Management in the Large Marine Ecosystems of Alaska

ABSTRACTEcosystem‐based fisheries management (EBFM) remains an aspirational goal for management throughout the world. One of the primary limitations of EBFM is the incorporation of basic lower trophic level information, particularly for zooplankton, despite the importance of zooplankton to fish. The generation of zooplankton abundance estimates requires significant time and expertise to generate. The rapid zooplankton assessment (RZA) is introduced as a tool whereby nontaxonomic experts may produce rapid zooplankton counts shipboard that can be applied to management in near real time. Zooplankton are rapidly counted shipboard and placed into three broad groups of zooplankton relevant to higher trophic levels: large copepods (> 2 mm), small copepods (< 2 mm), and euphausiids. A Bayesian, hierarchical linear regression modeling approach was used to validate the relationship between RZA abundances and laboratory‐processed abundances to ensure the rapid method is a reliable indicator. Additional factors likely to impact the accuracy of the RZA abundance predictions were added to the initial regression model: RZA sorter, survey, season, and large marine ecosystem (Bering Sea, Chukchi/Beaufort Sea, and Gulf of Alaska). We tested models that included the random effect of sorter nested within survey, which improved fits for both large copepods (Bayes R2 = 0.80) and euphausiids (Bayes R2 = 0.84). These factors also improved the fit for small copepods when the fixed effect of season was also included (Bayes R2 = 0.65). Additional RZA data were used to predict laboratory‐processed abundances for each zooplankton category and the results were consistent with model training data: large copepods (Bayes R2 = 0.80), small copepods (Bayes R2 = 0.64), and euphausiids (Bayes R2 = 0.88). The Bayesian models were therefore able to predict laboratory‐processed abundances with an associated error when accounting for these fixed and random effects. To demonstrate the utility of zooplankton data in management, zooplankton time series from the Bering Sea shelf were shown to vary in relation to warm and cold conditions. This variability impacted commercially important fish, notably Walleye Pollock (Gadus chalcogrammus), and these time series were used by managers using a risk table approach. The RZA method provides a rapid zooplankton population estimation in near real time that can be applied to the management process quickly, thus helping to fill a gap in EBFM.

Mercury Speciation and Stable Isotopes in Emperor Penguins: First Evidence for Biochemical Demethylation of Methylmercury to Mercury-Dithiolate and Mercury-Tetraselenolate Complexes

Apex marine predators, such as toothed whales and large petrels and albatrosses, ingest mercury (Hg) primarily in the form of methylmercury (MeHg) via prey consumption, which they detoxify as tiemannite (HgSe). However, it remains unclear how lower trophic level marine predators, termed mesopredators, with elevated Hg concentrations detoxify MeHg and what chemical species are formed. To address this need, we used high energy-resolution X-ray absorption near edge structure spectroscopy paired with nitrogen (N) and Hg stable isotopes to identify the chemical forms of Hg, Hg sources, and species-specific δ202Hg isotopic values in emperor penguin, a mesopredator feeding primarily on Antarctic silverfish. The penguin liver contains variable proportions of MeHg and two main inorganic Hg complexes (IHg), Hg-dithiolate (Hg(SR)2) and Hg-tetraselenolate (Hg(Sec)4), each characterized by specific isotopic values (δ202MeHg = 0.3 ± 0.2‰, δ202Hg(SR)2 = −1.6 ± 0.2‰, δ202Hg(Sec)4 = −2.0 ± 0.1‰). Using δ15N as a tracer of food source, we show that Hg(SR)2 is likely not obtained through dietary intake, but rather is present as a biochemical demethylation product. Furthermore, on average, female penguins transferred Hg to the egg strictly as MeHg in the egg albumen but as mixtures of MeHg and IHg in the membrane (89% and 11%, respectively) and yolk (32% MeHg and 68% Hg(Sec)4). Despite IHg species in eggs, MeHg is still the main species quantitatively transferred by the mother to the chick because of the disproportionate mass of the MeHg-rich albumen compared to the yolk. This work highlights the transformation of MeHg to Hg(SR)2 during demethylation for the first time in multicellular organisms, but further work is needed to understand the formation of Hg(SR)2 in the presence of relatively abundant Se biomolecules in lower trophic level predator species.

Potter Cove's Heavyweights: Estimation of Species' Interaction Strength of an Antarctic Food Web.

In the West Antarctic Peninsula, global warming has led to severe alterations in community composition, species distribution, and abundance over the last decades. Understanding the complex interplay between structure and stability of marine food webs is crucial for assessing ecosystem resilience, particularly in the context of ongoing environmental changes. In this study, we estimate the interaction strength within the Potter Cove (South Shetland Islands, Antarctica) food web to elucidate the roles of species in its structure and functioning. We use these estimates to calculate food web stability in response to perturbations, conducting sequential extinctions to quantify the importance of individual species based on changes in stability and food web fragmentation. We explore connections between interaction strength and key topological properties of the food web. Our findings reveal an asymmetric distribution of interaction strengths, with a prevalence of weak interactions and a few strong ones. Species exerting greater influence within the food web displayed higher degree and trophic similarity but occupied lower trophic levels and displayed lower omnivory levels (e.g., macroalgae and detritus). Extinction simulations revealed the key role of certain species, particularly amphipods and the black rockcod Notothenia coriiceps, as their removal led to significant changes in food web stability and network fragmentation. This study highlights the importance of considering species interaction strengths in assessing the stability of polar marine ecosystems. These insights have crucial implications for guiding monitoring and conservation strategies aimed at preserving the integrity of Antarctic marine ecosystems.

Trophic Position Stability of Benthic Organisms in a Changing Food Web of an Arctic Fjord Under the Pressure of an Invasive Predatory Snow Crab, Chionoecetes opilio

The introduction of a large predatory snow crab, Chionoecetes opilio, into the Kara Sea is a unique situation where the impact of an invasive species affecting an otherwise undisturbed ecosystem can be observed unhindered by other ecosystem stressors. Trophic interactions are one of the principal relationships between animals and can help assess an ecosystem’s stability. The trophic positions and sources of organic material for the most common benthic species of Blagopoluchiya Bay sampled at different stages of the invasion were calculated using stable isotope analysis. The most pronounced changes in the trophic web occurred amongst the megabenthic species, where previously most abundant deposit-feeding ophiuroids have disappeared. However, the benthic species’ trophic position and primary production source preference did not change. A sea star, Urasterias lincki, remained the highest carnivore in the bay, and the invasive crab remained at a lower trophic level, showing higher omnivory in its diet. Any changes in the consumers’ prey items were within the same trophic level. Overall, active predators became one of the most abundant feeding mode groups. The average weighted trophic position of all megabenthic species increased to the third trophic level, where mostly secondary consumers remained.

Study on the structure and energy flow of the salt marsh wetland ecosystem in Liaohe Estuary based on the Ecopath model

Salt marshes are one of the three blue carbon ecosystems recognized by the Intergovernmental Panel on Climate Change (IPCC). However, coastal salt marshes in China are facing the risk of degradation. To reveal the status of the salt marsh wetland ecosystem in Liaohe Estuary, an Ecopath model composed of 14 functional groups was constructed based on the 2019 ecological survey data. A comprehensive analysis of the system’s food web structure, energy flow processes, and overall ecosystem characteristics was conducted. The results show that the energy flow in the Liaohe Estuary salt marsh wetland ecosystem is mainly distributed in three integrated trophic levels. The utilization rates of trophic levels II and III are low, easily causing blockages in the lower trophic levels of the ecosystem’s energy flow. The total system throughput of the Liaohe Estuary salt marsh wetland ecosystem is 49,099.039 t·km²·a−1;. The system connectivity index and the system omnivory index are 0.207 and 0.109, respectively. Compared with other wetland systems, the ecosystem has a larger scale, but the overall ecosystem characteristic index reveals lower stability and complexity of the Liaohe Estuary salt marsh wetland system.

Spatiotemporal changes in the community and demography of mesozooplankton in the eastern Indian sector of the Southern Ocean during austral summer 2018/2019

The Southern Ocean is facing rapid environmental changes. However, few studies have been conducted on the spatiotemporal variability of mesozooplankton communities under recent climatic conditions, particularly in the eastern Indian sector. This study describes the spatiotemporal variability of the mesozooplankton community and the demographics of large copepods and krill in this sector, sampled through a Rectangular Mid-Water Trawl with 1 m2 mouth area (RMT1) during the austral summer of 2018/2019 as part of the KY1804 survey. Cluster analysis indicated that the mesozooplankton community was divided into five groups that showed only small longitudinal differences, as they were affected by oceanic fronts. Part of the variability was explained by physical (local upwelling) and biological features (e.g., the occurrence of species showing a specific spatial distribution, such as Euphausia crystallorophias). Horizontal changes in the zooplankton community structure were not attributed to temporal changes during the 2-month sampling period. The demographics of the dominant species, Calanoides acutus, Calanus propinquus, Metridia gerlacheri, and Thysanoessa macrura, exhibited significant temporal differences in abundance or mean stage index (MSI) between the early and late seasons. These differences matched the growth rates estimated in previous studies, suggesting that their growth during the study period was constant without regional differences. There were no evident changes in the abundance or demographics of Rhinalanus gigas, suggesting that they were in their reproductive season. These species-specific demographics could be explained by the species life cycles: growth in C. acutus and C. propinquus and reproduction in R. gigas during the austral summer. Abundances and MSIs confirmed the growth of dominant copepods and krill during the sampling period; however, no evident seasonal changes were observed in the zooplankton community structure. The findings of this study contribute to the understanding of lower trophic levels in marine ecosystems and the present carbon cycle in the eastern Indian sector of the Southern Ocean.

What is happening to the European Union aquaculture production? Investigating its stagnation and sustainability

While global aquaculture production has been highly successful in terms of production growth in recent decades, most developed countries including the European Union (EU) have not participated in this development to a significant extent. As recently as the 1970s, several EU countries were global leaders in aquaculture production, primarily focusing on filter feeders such as mussels and oysters. However, aquaculture production in the EU has largely stagnated over the past few decades. Despite political support, investment and research efforts over the last three decades, environmental regulations and competition with other activities have slowed down or even halted production growth in many cases. Recent EU legislation aimed at boosting food security and sustainable food systems, recognise aquaculture as a major potential contributor, focusing for example on sustainable or low environmental impact aquaculture, e.g. the production of low trophic level species. In this context, this article aims to contribute to the understanding of the EU aquaculture sector by examining the stagnation in production and its causes. We investigate the evolution of the EU aquaculture production in weight and value, as well as its average trophic level, length and diversity of the species produced. Results indicate an increase in the diversity of species produced, but a decline in the production of low trophic level species over the last two decades, and an increase in more challenging high trophic levels species, raising the overall average trophic level of the production. The decline in mussel and oyster production is mainly due to environmental and, to a lesser degree, economic factors. The rapid growth of carnivorous fish, such as seabream, seabass and salmon has slowed down since 2000, mainly due to regulations aiming at limiting environmental impacts.

Food web structure across basins in Lake Erie, a large freshwater ecosystem

Understanding spatial variation of aquatic food web structure and how ecosystem boundaries should be delineated is important. Here, we investigated the spatial variation in food web structure within Lake Erie across its three basins using δ13C and δ15N. Fish and lower trophic level composition were similar but differences in food web structure were observed between basins. The food web in the central basin had the smallest δ13C and δ15N range and total area based on stable isotope values by the aquatic community, likely due to chronic epibenthic hypoxia in the summer that affects fish habitat and resources. The largest δ15N range was in the east, driven by the high trophic position of lake trout present in this deepest basin. The western basin had the largest mean distance to the centroid (CD) of all three basins, indicating a large trophic diversity, probably due to high nutrient loadings and productivity. This research revealed spatial variability of food web structure in large lake ecosystems and the importance of considering smaller sub-units, such as basin, in large lakes.

The Dynamics of Trophic Cascades on Phytoplankton Induced by Mesozooplankton in Coastal Water, Daya Bay, Northern South China Sea

Daya Bay, a semi-enclosed bay in the northern South China Sea and to the east of the Pearl River Estuary, is rich in biological resources and diverse habitats. Current research on mesozooplankton in Daya Bay has mainly focused on aspects such as species composition, biomass, and biodiversity in the zooplankton community. However, there is limited research on the top-down effects of mesozooplankton on prey communities. This study conducted seasonal in-situ cultivation experiments from 2015 to 2017. By combining mesozooplankton grazing experiments and microzooplankton dilution experiments, the mesozooplankton clearance rate and trophic cascading effect on low trophic levels were calculated. Results showed evident mesozooplankton selective feeding behavior and corresponding trophic cascades with seasonal variations, these being significantly higher in the spring and summer and lower in the autumn and winter. Different sizes of phytoplankton showed significant differences; large-sized phytoplankton received high feeding rates but low trophic cascades by mesozooplankton, while the opposite was true for small-sized phytoplankton. Trophic cascades contribute in three ways: offsetting direct grazing mortality, changing prey community structure via its effects on different phytoplankton sizes, and reducing ciliate grazing impacts at an average of 14.4 ± 7.8%, maintaining around 70% ciliate grazing impacts in nature. The composition of mesozooplankton was the primary reason for explaining feeding preferences, including size selectivity and omnivory. For instance, high cladoceran abundance caused high feeding rates while, on the other hand, high omnivorous copepods abundance caused high trophic cascades on small-sized phytoplankton. General additive model (GAM) analysis revealed that the changes in trophic cascades were highly dependent on temperature, ciliate abundance, mesozooplankton feeding rates on ciliates, and ciliate feeding rates on phytoplankton. The significance of this study lies in its contribution to providing valuable insights into the role of mesozooplankton in the marine food web and their impact on lower trophic levels. In addition, the findings can help inform the management and conservation of marine ecosystems, as well as guide future research in this field.

Multiple stressors drive multitrophic biodiversity and ecological network dynamics in a shrinking sandy lake

Stressors endanger lake ecosystem biodiversity and networks, especially in sandy lakes of arid/semiarid regions, where impacts are poorly understood. Here, we investigate the changes in multitrophic biodiversity and ecological networks under increasing stress (temperature, nutrients, lake area) by using sedimentary DNA from a shrinking sandy lake in China over nearly 100 years. With increasing stress, species richness and stability increased, whereas species turnover decreased. Species synchronism decreased at high-trophic levels but increased at low-trophic levels. Empirical dynamic modeling showed network connectance and strength of species interactions decreased–increased–decreased over time, signaling a potential adaption–resistance–degradation change in ecosystem responses with increasing stress. Models also indicated network structure primarily depended on direct effects of nutrients and temperature under low/medium stress and on a diversity-mediated pathway under high stress. Thus, maintaining ecological network structure complexity and integrity in lake ecosystems is essential to mitigate the effects of multiple stresses.

Butterfly species vary in sex‐specific sodium accumulation from larval diets

Abstract Sodium is essential for animals, and its heterogeneous distribution can cause a range of phenomena, from sodium‐seeking behaviours to impacting their performance. Although sodium content in soils and plants is relatively well documented, data for higher trophic levels are limited. Knowledge of the variation in sodium in lower trophic levels could have implications for understanding the behaviour and physiology of species at higher levels. We investigated the variation in tissue sodium concentration between males and females of four butterfly species. Puddling behaviour of Lepidoptera suggests sodium needs of males are generally greater than females, thus, we predicted males would accumulate more sodium than females on a given diet. Larvae were reared on plants (for Battus philenor, Chlosyne lacinia and Danaus plexippus) and an artificial diet (for Pieris rapae) under Low Na (no added sodium) and High Na (sodium added) conditions. Among species and sexes, we quantified and compared adult absolute tissue sodium concentrations and bioconcentration factors, which indicate net sodium accumulation or excretion relative to individuals' diets. On average, individuals on low‐sodium diets had higher bioconcentration values across all species. Male butterflies accumulated significantly higher sodium concentrations than females in two sodium treatments for B. philenor, and P. rapae and only in the High Na treatment for C. lacinia. However, in D. plexippus, individuals accumulate sodium in the High Na treatment, but males and females responded in the same way. Our study revealed sex‐ and species‐specific patterns of butterfly sodium accumulation, which could be linked to variations in behaviour and/or performance. Differences in sodium content across species have implications for variation in predation and trophic‐level interactions, an interesting avenue for future ecological and evolutionary research.

Microplastics in freshwater food chains: Priority list based on identification of oxidative stress response characteristic

Exogenous exposure to high concentrations of microplastics (MPs) cause oxidative damage to freshwater food chains (FFCs). Thus, the patterns and mechanisms of oxidative stress responses (OSRs) induced by MPs in FFC organisms were investigated using theoretical simulation methods. Results showed an increasing (reduced) OSR was found in lower trophic levels (higher trophic levels). Besides, polycarbonate (polyvinyl chloride) causes the most (least) significant OSRs in FFC organisms, respectively. The impacts of MP additives were also analyzed using the full factorial experimental design, revealing flame retardants significantly influence oxidative stress variability. A constructive solution of "restriction-control-focus" is proposed for different types of MPs by the coefficient of variation-corrected CRITIC and the nested mean classification method. The mechanism analysis revealed a positive correlation between protein secondary structure orderliness and OSRs. Proteins in organisms that contain a high proportion of hydrophobic non-polar amino acids are more likely to bind to MP and enhance OSRs. This is the first study assessing the OSR patterns and ecological risks of MPs and their additives in FFCs with a proposed priority list, providing theoretical support for risk assessments and management strategies in freshwater environments.

Whole-lake coarse woody habitat addition facilitates ecosystem regime restructuring in an oligotrophic lake

Preul-Stimetz T, Shaw SL, Sass GG. 2024. Whole-lake coarse woody habitat addition facilitates ecosystem regime restructuring in an oligotrophic lake. Lake Reserv Manag. XXX-XXX. The loss of vital littoral zone and riparian habitat due to lakeshore residential development is a pervasive issue across temperate aquatic ecosystems. Oligotrophic glacial lakes may be particularly vulnerable to reductions in coarse woody habitat (CWH) due to their lack of alternative structural habitat. Although influences of CWH on fish populations have been well documented, questions remain regarding CWH influences on lower trophic levels and water quality. We conducted a whole-lake CWH addition experiment within a BACI framework using 2 lakes, Sanford (treatment) and Escanaba (reference), in the Northern Highland Lake District of Wisconsin. Premanipulation monitoring began in 2015, trees were dropped in 2018, and data collection continued until 2023. We monitored limnological, planktonic, and benthic macroinvertebrate parameters to test whether CWH addition initiated trophic shifts and altered the structure of the aquatic food web. We found that CWH addition minimally affected water quality and changed some characteristics of Sanford Lake at lower trophic levels. Chlorophyll a concentrations in Sanford Lake significantly increased but Secchi depth was unaffected. The abundance of macrophytes increased in both systems; that in Sanford Lake increased more and was linked to the CWH addition. Dissolved oxygen significantly increased at multiple depth strata. Water temperature was unaffected. We observed declines in total zooplankton that were not related to CWH addition, but the decline in relative abundance of large grazers was. Our results provide a mechanistic understanding of the effects of habitat enhancement at an ecosystem scale and can help guide stakeholder and manager expectations following CWH addition.

Flow velocity determines detritus availability and microbial food web patterns in a river confluence

Detritus is the vital support for the microbial food web, which would further affect river ecological conditions. Determining the effects of detritus availability on microbial food webs in rivers is critical for protecting river ecological functions. However, the detritus availability was difficult to estimate directly, since the detritus transformation processes (i.e. detritus availability) and flow-induced transport processes are interdependent in rivers. Therefore, this study quantified the detritus transformation processes in a natural river and further identified the impacts of detritus availability on microbial food web patterns. Results revealed that the flow velocity was the main physical driver determining the detritus availability. The decreased velocity would promote detritus availability. Moreover, the increased detritus availability significantly promoted the diversity of bacteria, protozoan and metazoan (p < 0.05). The responses of low trophic levels to detritus availability were significantly greater than those of higher trophic levels, emphasizing the bottom-up cascading effect of detritus availability on microbial food web composition (p < 0.05). From microbial food web perspectives, the detritus availability was amplified with flow velocity decreased, promoting trophic transfer efficiency between different trophic levels. Results and findings revealed the ecological effect of detritus transformation processes on multi-trophic levels in rivers and provided advantageous information for river management.

Two-year assessment of the effects of controlled sediment flushing on stream habitats and biota at reach scale

Controlled sediment flushing operations (CSFOs) allow to recover reservoirs storage loss while rebalancing the sediment flux interrupted by dams but, at the same time, may cause unacceptable ecological impact. In this study, we investigated the responses of the food web of an upland stream to a CSFO, focusing on the effects of fine sediment deposition detected in three different mesohabitats, i.e., a pool, a riffle, and a step-pool. The field campaign lasted two years and included repeated measurements of fine sediment deposits, and sampling of periphyton, benthic macroinvertebrates and fishes. A moderate and patchy deposition occurred due to the CSFO with short and medium-term ecological impact on the lower trophic levels of the food web, which may affect the whole ecosystem functioning. The monitoring of all available mesohabitats in the investigated stream allowed to detect variations in the ecological response to CSFO, providing a more adequate assessment of the impact. As expected, sedimentation was larger in the pool but, in contrast to our hypotheses, the impact was lower and the recovery was longer for the benthic organisms inhabiting the riffle. In the case of fishes, no lethal impact of both brown trout and bullhead was recorded in the short term but the occurrence of longer lasting effects could not be excluded. To date, this is one of the few studies dealing with a detailed integrative assessment of the downstream impact of sediment management from reservoir on both abiotic and biotic components of stream ecosystem.

Biodiversity of multi-trophic biological communities within riverine sediments impacted by PAHs contamination and land use changes

River ecosystems currently face a significant threat of degradation and loss of biodiversity resulting from continuous emissions of persistent organic pollutants and human activities. In this study, multi-trophic communities were assessed using DNA metabarcoding in a relatively stable riverine sediment compartment to investigate the biodiversity dynamics in the Beiluo River, followed by an evaluation of their response to polycyclic aromatic hydrocarbons (PAHs) and land use changes. A total of 48 bacterial phyla, 4 fungal phyla, 4 protist phyla, 9 algal phyla, 31 metazoan phyla, and 12 orders of fish were identified. The total concentration of PAHs in the Beiluo River sediments ranged from 25.95 to 1141.35 ng/g, with low molecular weight PAHs constituting the highest proportion (68.67%), followed by medium (22.19%) and high (9.14%) molecular weight PAHs. Notably, in contrast to lower trophic level aquatic communities such as bacteria, algae, and metazoans, PAHs exhibited a significant inhibitory effect on fish. Furthermore, the diversity of aquatic communities displayed obvious heterogeneity across distinct land use groups. A high proportion of cultivated land reduced the biodiversity of fish communities but increased that of metazoans. Conversely, an elevated proportion of built-up land reduced metazoan biodiversity, while simultaneously enhancing that of fungi and bacteria. Generally, land use changes exert both indirect and direct effects on aquatic communities. The direct effects primarily influence the abundance of aquatic communities rather than their diversity. Nevertheless, PAHs pollution may have limited potential to disrupt community structures through complex species interactions, as the hub species identified in the co-occurrence network did not align with those significantly affected by PAHs. This study indicates the potential of PAHs and land use changes to cause biodiversity losses. However, it also highlights the possibility of mitigating these negative effects in riverine sediments through optimal land use management and the promotion of enhanced species interactions.

Impacts of glacial discharge on the primary production in a Greenlandic fjord

Subglacial discharge from marine-terminating glaciers in Greenland injects large volumes of freshwater and suspended sediment into adjacent fjord environments. Although the discharge itself is nutrient poor, the formation of meltwater plumes can enhance marine biological production by stimulating upwelling of nutrient-rich fjord water. Despite the importance of meltwater discharge to marine ecosystems, little is known of the quantitative impact of discharge processes on phytoplankton growth, including the effects of local plumes, fjord-wide stirring and mixing, and suspended sediments on net primary production (NPP). Here, we report simulations of Bowdoin Fjord in northwestern Greenland using coupled non-hydrostatic ocean circulation and lower-trophic level ecosystem models, developed using field data. Our findings demonstrate that subglacial discharge plays a crucial role in NPP by stirring and mixing the entire fjord water system, which has a greater effect on NPP than local plume upwelling. Sensitivity tests suggest a 20% increase in NPP under conditions of enhanced discharge anticipated in the future. However, if glacier discharge and retreat exceed critical levels, NPP is predicted to decline by 88% relative to present values. This pattern reflects the negative impact of increased sediment flux on photosynthesis and weakened fjord stirring and mixing resulting from shallower outlet depths.

European consumers' intention to buy sustainable aquaculture products: An exploratory study

Given the increasing global importance of low trophic level aquaculture (LTA) products (e.g. seaweed and mussels) for sustainable and healthy seafood supply, this study examined consumer intentions towards LTA products among European consumers. This study performed an extended theory of planned behaviour to focus on the influence of health consciousness, subjective knowledge, food neophobia, and sociodemographic and lifestyle factors on consumers' intentions to buy LTA products. We conducted an online questionnaire survey in Denmark, the United Kingdom and France (~500 respondents per country). Consumer segmentation analysis, based on food-related lifestyles, employing K-means clustering techniques, revealed five distinct segments, namely ‘Adventurous’, ‘Uninvolved’, ‘Foodies’, ‘Rational’, and ‘Conservative’, each reflecting unique consumer behavioural patterns. Furthermore, partial least squares structural equation modelling analysis revealed that subjective norms are the main predictor of LTA product buying intention, followed by attitude, food neophobia, subjective knowledge, and health consciousness. Furthermore, food neophobia seems to moderate the influence of subjective norms and subjective knowledge on LTA product buying intention. This dual approach explains the predictive power of the model while identifying targeted segments for sustainable aquaculture product marketing, ensuring that the distinction between the model's test and the subsequent segmentation analysis is clearly articulated. To enhance the adoption of LTA products, marketers should primarily target the ‘Foodies’ segment, characterised by high involvement and innovation, by emphasizing attitudes, health consciousness, subjective knowledge, and food quality attributes, while mitigating food neophobia and leveraging subjective norms.

Fishing Eco-Efficiency of Ports in Northwest Spain

Fishing is an essential economic activity and source of livelihood for millions of people worldwide. However, overfishing and unsustainable practices have led to a decline in fish populations and the degradation of marine ecosystems. Moreover, fishing activities can contribute to climate change through the emission of greenhouse gases (e.g., carbon dioxide and methane) from fishing vessels and seafood transportation. To mitigate the environmental impacts of fishing activities, sustainable fishing practices must be implemented to minimize the negative impacts of fishing on the environment while maintaining the productivity and diversity of fish populations and ecosystems. These practices include using selective fishing gear, avoiding fishing in vulnerable habitats, implementing fishery management plans, and reducing the carbon footprint of the fishing industry. To this end, and as a first step in defining efficient and effective measures towards the sustainability of capture fishing activity, an analysis of the environmental sustainability of the Galician fishing sector, one of the main European regions in this field, is presented in this work. An ecosystem-based indicator (ecological footprint, calculated by adding the so-called fishing ground footprint and the carbon footprint) was employed to quantify the main impacts of capture fishing during extractive activity. The catch composition and fuel consumption of the fleet based on the vessels’ power, and economic benefits, were the parameters used in this analysis. The results showed that ports with larger vessels and fleets seem to be more eco-efficient than those concentrating smaller vessels in targeting lower trophic level species.

A taste of youth: Seasonal changes in the diet of immature white sharks in eastern Australia

White sharks (Carcharodon carcharias) play a crucial ecological role, shaping ecosystems through direct predation and risk effects. On the east coast of Australia, immature white sharks are broadly distributed, inhabiting a wide range of habitats and ecosystems from temperate Tasmania to tropical North Queensland. Using stable isotopes and fatty acids of muscle and plasma, we examined the diet and habitat use of 136 immature white sharks (152–388 cm total length) captured on SMART drumlines on the East Australian coast. This facilitated the temporal assessment of white shark trophic ecology from a few weeks to approximately a year. Biochemistry of muscle samples showed that white sharks predominantly feed on low trophic level prey from coastal environments. A seasonal shift in diet was evident, with the increasing proportions of essential fatty acids in muscle tissues during spring and summer suggesting a greater consumption of high-nutrition preys during those months compared to autumn and winter. By combining stable isotope and fatty acid analysis, we gain a comprehensive understanding of immature white shark diet in eastern Australia. Our results confirm that white sharks are generalist predators that exhibit seasonal shifts in their diet. Their high use of coastal habitats reinforces the importance of these areas for foraging, which is crucial for growth and development during this critical life stage.