Trophic Niche Dynamics and Diet Partitioning of King Crab Lithodes santolla in Chile’s Sub-Antarctic Water

The southern king crab Lithodes santolla is one of the most economically important fishery species in the southern waters of the Atlantic and Pacific Oceans. A combination of stomach content and stable isotope analyses was used to reveal the potential dietary characteristics, isotopic niche, overlap among maturity stages and sexes, and trophic relationships of an L. santolla population in the Nassau Bay, Cape Horn region. Stable isotope analyses indicated that L. santolla assimilated energy from a basal carbon source, the giant kelp Macrocystis pyrifera, forming the trophic baseline of the benthic food web. Moreover, the trophic position of L. santolla varied among late juveniles and adults, suggesting that the southern king crab does undergo an ontogenetic diet shift. L. santolla exhibited intraspecific isotopic niche variation, reflecting niche differentiation which allows the species to partition resources. The trophic relationships of L. santolla with the associated fauna suggested some potential interactions for food resources/habitat use when they are limited. This study is the first attempt to characterize the trophic dynamics of the southern king crab in the Cape Horn area and, by generating more data, contributes to the conservation of the king crab population and the long-term management of local fisheries that rely on this resource.

Spatial Heterogeneity in Prey Availability, Feeding Success, and Dietary Selectivity for the Threatened Longfin Smelt

Food availability is a key determinant of the nursery value of a given habitat for larval and juvenile fishes. Growth, survival, and recruitment success are often inter-correlated and influenced by prey availability and associated feeding success. This is likely true for the threatened population of Longfin Smelt (Spirinchus thaleichthys) in the San Francisco Estuary (SFE) which has collapsed in recent decades along with its preferred prey. In years with high precipitation and freshwater outflow, larval Longfin Smelt are found in shallow wetland habitats throughout the SFE, but variation in the availability of food and feeding success in these habitats remains unexplored. To examine spatial variation in the trophic value of different rearing habitats, we quantified variation in prey availability, feeding success, and prey selection for larval and juvenile Longfin Smelt captured in restored tidal marshes, sloughs, and open-water habitats in the northern and southern SFE. Prey abundance varied spatially, with densities approximately tenfold greater in southern sloughs and restored tidal ponds relative to northern and open-water habitats. Feeding success of larval Longfin Smelt was positively correlated with both fish length and prey density. Larval Longfin Smelt fed selectively on the copepod Eurytemora affinis, with larger individuals (> 25 mm total length) exhibiting an ontogenetic diet shift to larger mysid shrimps. Our results suggest that wetland habitats across the SFE vary greatly in their trophic value, with previously unexplored habitats exhibiting the highest densities of prey and the highest foraging success for larval Longfin Smelt.

Employment and income implications of transitions towards more sustainable global diets

The effect of global diet shifts on human health, the natural environment, and the financial cost of obtaining food has been extensively quantified. The current study complements these quantifications by examining the economy-wide consequences of global diet shifts. We used a computable general equilibrium model to quantify the changes in employment and income in all geographic regions of the globe in the year 2050 under a global shift towards more sustainable human diets. These more sustainable diets are lower in livestock-derived foods, higher in fruit and vegetables, and lower in refined sugar than diets under the current trajectory for food demand out to the year 2050. Our results show that transitioning towards more sustainable diets at the global scale in sub-Saharan Africa will decrease employment in the livestock sector and increase employment in the crop sector, with an overall reallocation of labor from the industry and services sectors to the agriculture sector. West Africa was the region of the globe that encountered the greatest decline in income of 14% as a result of the global diet shift, driven by the reallocation of labor into the lower value-added agriculture sector and driven by West Africa’s high share of total household expenditure spent on food. These findings have important implications for understanding trade-offs and developing strategies to equitably improve livelihoods within the broader context of food system transformation.

Diet overlap and feeding preference of Oreochromis niloticus (Linnaeus, 1758) versus two native cichlids of the upper Kabompo River, northwest of Zambia.

Evaluating the food and feeding habits of fish is fundamental in fisheries and conservation biology research. In this study, the diet of exotic Oreochromis niloticus was compared with the 2 most abundant and aquaculture preferred native cichlids of native species (Orochromis macrochir and Coptodon rendalli) in the upper Kabompo River, Zambia. We hypothesized that exotic and native cichlids would show no dietary niche overlap. We analyzed the stomach contents of 114 specimens of the fishes sampled. Fishes were grouped into 3 major feeding groups: microphages, macrophages and carnivores, and omnivores. They were also grouped into size classes of <50, 51−100, 101−150, and 151−302 mm total length (TL). O. niloticus had a larger dietary niche than two native species (71% and 22%, respectively). The dietary niche overlap between O. niloticus and native C. rendalli species in size classes <50 was significant (F (2, 45) = 0.084, p < 0.05). Dietary niche overlap between the native O. macrochir species in size class <50 mm was low (F (2, 33) = 2.13, p > 0.05), while as in size classes 51−100 mm and 101−150 mm was high (F (2, 35) = 0.27, p < 0.05) for C. rendalli. There was no clear evidence of ontogenetic diet shift of native cichlids, with the exception of O. macrochir, which showed ontogenetic diet shifts within the 51−100 mm size class. The dietary overlap results indicate interspecific competition between exotic O. niloticus and native O. macrochir, which may have major impacts on food web structure in the upper Kabompo River and may explain population decreases of some native species.

Host Factors Affect the Gut Microbiome More Significantly than Diet Shift

The determining factors of the composition of the gut microbiome are one of the main interests in current science. In this work, we compared the effect of diet shift (DS) from heavily relying on meatatarian diets to vegetarian diets and physical exercise (EX) on the composition of the gut microbiome after 3 months. Although both DS and EX affected the composition of the gut microbiome, the patterns of alteration were different. The α-diversity analyzed by InvSimpson, Shannon, Simpson, and Evenness showed that both EX and DS affected the microbiome, causing it to become more diverse, but EX affected the gut microbiome more significantly than DS. The β-diversity analyses indicated that EX and DS modified the gut microbiome in two different directions. Co-occurrence network analysis confirmed that both EX and DS modified the gut microbiome in different directions, although EX modified the gut microbiome more significantly. Most notably, the abundance of Dialister succinatiphilus was upregulated by EX, and the abundances of Bacteroides fragilis, Phascolarctobacterium faecium, and Megasphaera elsdenii were downregulated by both EX and DS. Overall, EX modulated the composition of the gut microbiome more significantly than DS, meaning that host factors are more important in determining the gut microbiome than diets. This work also provides a new theoretical basis for why physical exercise is more health-beneficial than vegetarian diets.

Potentials and perspectives of food self-sufficiency in urban areas—a case study from Leipzig

Regionalization of food systems is a potential strategy to support environmental, economic and social sustainability. However, local preconditions need to be considered to assess the feasibility of such a transformation process. To better understand the potentials and perspectives of food self-sufficiency in urban and peri-urban areas, we determined the food self-sufficiency level (SSL) of a German metropolitan region, i.e., the percentage of the food demand that could be potentially provided on existing agricultural land. Main input parameters were actual food demand, agricultural productivity and its temporal variability and land availability. Furthermore, we considered changes in diet, food losses and land management. Based on current diets and agricultural productivity, the administrative region of Leipzig achieved a mean SSL of 94%, ranging from 77 to 116%. Additionally, an area of 26,932 ha, representing 12% of the regionally available agricultural land, was needed for commodities that are not cultivated regionally. Changes in food demand due to a diet shift to a more plant-based diet and reduced food losses would increase the SSL by 29 and 17%, respectively. A shift to organic agriculture would decrease the SSL by 34% due to lower crop yields compared with conventional production. However, a combination of organic agriculture with less food loss and a more plant-based diet would lead to a mean SSL of 95% (75–115%). Our results indicate the feasibility of food system regionalization in the study area under current and potential near future conditions. Addressing a combination of multiple dimensions, for example plant-based and healthier diets combined with reduced food loss and organic farming, is the most favorable approach to increase food self-sufficiency in urban and peri-urban areas and simultaneously provide synergies with social and environmental objectives.

New insight into the trophic position and ecological role of the European hake (Merluccius merluccius L., 1758) in Central and Southern Tyrrhenian Sea (Western Mediterranean Sea)

This paper aims to investigate the ecological role of Merlucicius merluccius, Linnaeus, 1758, in the southern and central Tyrrhenian Sea (GSA 10, Resolution GFCM/33/2009/2 General Fisheries Commission for the Mediterranean), analysing ontogenetic diet shift, geographical variations on prey composition and feeding habits. A sample of 734 hake specimens between 6 cm and 73 cm of total length (TL) were collected in 2018. To value the ontogenetic shifts in prey composition, five size-classes were created from the sample and for each class were calculated quantitative feeding indices. The cluster and MDS analysis, based on the % IRI, resulted in three trophic groups of hake size classes. The most abundant preys for small hake (size class I) were the Euphausiids, Stylocheiron longicorne and Mysidacea, while for hake with size over 10.5 cm of TL were crustaceans and fish. Engraulis encrasicolus was the most abundant prey fish for hake, followed by Boops boops and Myctophids. The mesopelagic fauna had a relevant role in the European hake diet in the southern zone. The high presence of Euphausiids, Mysids, Myctophidae and Sternoptychidae in the gut content of juvenile hakes (6-23 cm) showed the importance of organic matter and energy flowed from the mesopelagic environment to the epipelagic. Important is also the presence of decapod crustaceans in hake with size over 36 cm TL considering that our study area includes an important Gulf for the fishing of decapod crustacea.

The occurrence of accidents and injury in mining shift worker influenced by food intake, a short review

Introduction: Identifying factors that contribute to occupational accidents has been a general concern of companies in the present millennium. One of the factors identified is the quality and quantity of food, as well as meals times. In this context, the present systematic review aimed to identify how food intake influences the occurrence of accidents in shift work, with some focus, although not exclusive, on the mining industry. Methodology: The research-based literature was carried out in four electronic databases: Medline/PubMed, Science Direct, Scopus and Web of Science. Have been combined the following words “occupational accident” and “food intake”; “mining injury” and “food choice”; “meal timing” and “workplace”; “eating at night” and “mining injury”;“Circadian rhythm” and “diet shift”; “Food safety” and “ Health risk”; “workplace accidents” and “food choice”. Results: It was possible to identify 24 articles related to food intake. To better understand the analysis, the results were organized into five groups: Author surname and year, Study type, Accidents/injury causes, risk factor, Conditions for accidents/injuries to occur. Through the groups of causes, it was possible to regrouped on three, which facilitated the discussion of the topic; food choice n=10 (42%) articles, eating habits n=9 (37.5%), and emotional commitment n=5 (20.5%), showed the relativity of food intake causes for the occurrence of accidents and illnesses in shift workers. Discussion: The reviewed articles demonstrated that the materialisation of accidents was due to the relationship between food intake and consumption of nutrient-poor foods in shift work. That can develop chronic diseases, metabolic disorders such as blood pressure abnormalities, blood sugar fluctuation (dyslipidemia, dysglycemia), and obesity, neurobehavioural performance. Foods contain high content As, Cd, Cr, Hg, Fe, and Mn above the recommended standards by the FAO/WHO. Sleep disturbance during the 12-hour shift interferes with circadian rhythm and, consequently,with performance. These factors can be related to food and the precarious physical environment, increased workload, fatigue and poor diet, especially at night. Conclusion: In conclusion, the study demonstrated how food intake impacted workers' health on shifts but did not determine the causes or risk factors contributing to accidents/injuries. Further studies are needed to demonstrate a direct relationship which the risk factor of food intake and causes accidents/injuries.

Coral defences: the perilous transition of juvenile crown-of-thorns starfish to corallivory

The transition from the post-settlement herbivorous juvenile to the coral-eating stage of crown-of-thorns starfish (COTS) is a fundamental step to seed population outbreaks that decimate tropical coral reefs. How the highly cryptic juveniles fare during this transition is poorly understood. We show that the juveniles are vulnerable to attack by coral during this ontogenetic diet shift to coral prey. We monitored the condition, growth, and survival of juvenile COTS during the first 3.5 mo on a diet of Acropora sp. In initial encounters, juveniles often withdrew their arms to avoid the defensive nematocysts of the corals. Within the first 67 d of being offered coral, 37.8% of the juveniles experienced various levels of sublethal and lethal damage. Damaged arms were reduced to ~65.4% of the length of an intact arm, but most injured juveniles were able to regenerate their arms with an average predicted recovery time of ~4 mo. Although sublethal damage slowed the growth of injured juveniles, their capacity to regenerate is likely to contribute to the success of this highly prolific species. Despite being the prey of COTS, coral can influence the survival of juveniles, and potentially reduce their ecological impact by prolonging their growth to reproductive maturity, delaying their transition into a coral predator, and thereby hindering recruitment into the adult population.