Seasonal Food Availability Research Articles

Ontogenetic, Sexual, and Monthly Niche Segregation of Sepia esculenta in the Northern East China Sea Revealed by Stable Carbon and Nitrogen Isotopes.

Golden cuttlefish play a significant role in the food web of the East and Yellow Seas and are a valuable fishery resource in Chinese coastal waters. Samples of golden cuttlefish were obtained from the northern East China Sea between September 2021 and March 2022, and stable isotope methods were utilized in this study to examine the variations in the forage ecology of golden cuttlefish. Our findings reveal dynamic shifts in carbon and nitrogen stable isotopes (δ13C and δ15N), highlighting intricate foraging strategies tailored to growth and environmental changes. A notable trend emerges: an initial growth-linked rise in δ13C and δ15N enrichment, followed by seasonal fluctuations mirroring seasonal food availability. The ontogenetic niche evolution displays striking habitat shifts and trophic level escalation in small mantle length stages, transitioning to niche overlap and subtle trophic shifts later on. Sex-specific differences emerge, with females occupying higher trophic levels than males in most samples. This comprehensive study underscores the complexity and adaptability of golden cuttlefish feeding ecology, inviting further inquiry into their intricate relationships within the marine ecosystem.

Latitudinal life history gradients in two Pliocene species of Glycymeris (Bivalvia)

ABSTRACT Modern bivalves display a latitudinal life history gradient (LLHG): tropical bivalves tend to grow fast and die young, whereas mid- and high-latitude bivalves typically grow more slowly and may live much longer. Environmental factors such as temperature and seasonal food availability, both of which affect metabolic rates, are thought to be partially responsible for this pattern. Given that temperature influences life histories, we predict that the expression of individual life history gradients should vary over time with changes in global climate. Here, we use internal growth increments to constrain lifespans and growth rates in populations of Glycymeris americana and Glycymeris subovata along the Pliocene and Pleistocene Atlantic continental shelf of North America. We find that G. americana was long-lived (up to 93 years) and follows the expected pattern of longer life and slower growth at higher latitudes, whereas the shorter-lived (up to 36 years) G. subovata does not. G. americana life history data lend preliminary support for a change in the slope of the LLHG from the Pliocene to the Pleistocene. While G. americana is currently living along the U.S. Atlantic Coast, we were unable to obtain sufficient samples for our analysis; this represents a future area of research.

Weak seasonality in benthic food web structure within an Arctic inflow shelf region

The Arctic Ocean is characterized by pronounced seasonality in the quantity and quality of organic matter exported from the surface ocean. While it is well established that changes in food availability can alter the abundance, biomass and function of benthic organisms, the impact on food web structure is not well studied. We used bulk carbon and nitrogen stable isotope analysis to assess the quantity and quality of sediment organic matter and structure of the benthic food web in four seasons within the Northern Barents Sea (76°N − 82 °C). Despite a highly seasonal vertical flux, we found that the organic carbon and chlorophyll-a content of surface sediments was seasonally stable, suggesting a lack of seasonality in food availability at the seafloor. However, organic biomarkers indicate that the quality of sediment organic matter increased to a maximum in August and December, up to 6 months after the spring bloom. The seasonal stability of food quantity was mirrored in food-web structure (e.g., total isotopic range, number of trophic levels) which did not change significantly across sampling periods. We expected that suspension and deposit feeders would respond more readily to seasonal changes in food quality compared to predators. However, we observed no significant seasonal changes in the trophic levels or isotopic niche areas of benthic functional groups. The centroids of isotopic niches of all benthic functional groups shifted seasonally by <2 ‰ along the δ13C-axis, suggesting minimal shifts in carbon resource use. Because the northern Barents Sea experiences significant changes in seasonal sea ice cover, we expected that stable-isotope ratios of benthic organisms would show an increased consumption of sympagic-derived organic matter through less negative δ13C values in early spring and summer. However, only two taxa (the soft coral Gersemia spp. and bivalves in the family Yoldiidae) showed 13C-enrichment in spring or summer consistent with the assimilation of sympagic-derived organic matter, despite previous evidence suggesting widespread use of this carbon source. Overall, our results show that there is an apparent de-coupling in time between pelagic processes and benthic food-webs in which the accumulation and assimilation of high-quality organic matter occurs for benthos during the fall and early winter months when there is little to no fresh organic matter generated at the surface. This temporal mismatch highlights the importance of considering the timescales over which components of the marine ecosystem respond to short-term environmental changes and the methods employed to assess seasonality.

Seasonality of modelled planktonic food web structure in the Strait of Georgia, Canada

When attempting to model an ecosystem, compromises must be made to retain the essence of the system and its functioning. Here, we explore the implications of these aggregations on a modelled ecosystem by using Ecopath to model the plankton food web in the Strait of Georgia (SoG), a temperate coastal system on the west coast of Canada, in three seasons. The food web is defined by fifteen functional groups representing autotrophic phytoplankton, the microbial loop, and mesozooplankton in three seasons, differentiated by node biomass, productivity, and diet. Variations in the community composition lead to shifts in trophic behaviour and food-web structure seasonally. In spring, autotrophic phytoplankton (i.e. diatoms) are the main source of carbon for the system. In summer and winter, the microbial loop becomes more important due to limited primary production. These structural changes within the plankton food web throughout a year have implications for higher trophic levels, including the seasonal availability and quality of food for planktivorous fish. Finally, we compared this detailed seasonal approach to plankton modelling with a more common simplified approach and examined its impacts on the entire ecosystem. The microbial loop is often excluded from coastal ecosystem models but is an important component, influencing trophic positions and transfer efficiencies. However, aggregating plankton groups appears to be an adequate approach to plankton modelling in the SoG, but modelling decisions should be driven by the research question.

Revealing seasonal woolly mammoth migration with spatially-resolved trace element, Sr and O isotopic records of molar enamel

We investigated the mobility pattern of an Upper Palaeolithic woolly mammoth (Mammuthus primigenius) from the Kraków Spadzista site in southern Poland, one of the largest mammoth bone accumulations in Europe. We conducted in situ laser ablation (MC-) ICPMS Sr isotopic and trace element concentration measurements accompanied by spatially-resolved oxygen isotope measurements of dental enamel on a last upper molar tooth (M6). Our study documents excellent preservation of in vivo geochemical and isotopic records and reveals recurring changes in 87Sr/86Sr that oscillate between two endmembers and correlate with analogous variations in δ18O, as well as U and Sr concentrations. The observed periodicity corresponds to annual cycles of enamel mineralization as revealed by enamel histology and documents up to 11 years of woolly mammoths' life in a single dental plate. The high degree of correlation between the duration of enamel mineralization and the Sr and O isotopic records suggests that the mammoth migrated between two areas of distinct Sr isotopic composition as well as characteristic U and Sr concentrations, presumably forced by seasonal food availability. The mammoth grazed in southern Poland in winter time as indicated by lower δ18O values and likely moved 250–400 km northwards to the Polish midlands during summer. This migration pattern remained stable for at least 12–13 years of the animal's adult life as archived in this molar tooth. Our study documents a fixed mobility behaviour of an adult mammoth some 10,000 years before the Last Glacial Maximum.

Determinants of maternal, infant, and young child nutrition during the 1,000-day window of opportunity in Solomon Islands: A focused ethnographic study.

This focused ethnographic study used qualitative, ethnographic, and participatory methods to explore determinants of maternal, infant, and young child nutrition (MIYCN) during the first 1,000 days of life as part of efforts to address the double burden of malnutrition in Solomon Islands. An iterative study design was used to first explore and then confirm findings related to food and nutrition security and social and behavioral determinants of MIYCN in urban and rural settings. The first phase included in-depth interviews, household observations, free lists, and seasonal food availability calendar workshops while the second phase included focus group discussions, pile sorts, participatory community workshops, and repeated household observations. We found that MIYCN is shaped by a complex interaction of factors at the macro- and micro-levels. At the macro-level, globalization of the food system, a shifting economy, and climate change are driving a shift toward a delocalized food system based on imported processed foods. This shift has contributed to a food environment that leaves Solomon Islanders vulnerable to food and nutrition insecurity, which we found to be the primary determinant of MIYCN in this context. At the micro-level, this food environment leads to household- and individual-level food decisions that often do not support adequate MIYCN. Multi-sectoral interventions that address the macro- and micro-level factors shaping this nutrition situation may help to improve MIYCN in Solomon Islands.

Dietary strategies of Pleistocene Pongo sp. and Homo erectus on Java (Indonesia).

During the Early to Middle Pleistocene, Java was inhabited by hominid taxa of great diversity. However, their seasonal dietary strategies have never been explored. We undertook geochemical analyses of orangutan (Pongo sp.), Homo erectus and other mammalian Pleistocene teeth from Sangiran. We reconstructed past dietary strategies at subweekly resolution and inferred seasonal ecological patterns. Histologically controlled spatially resolved elemental analyses by laser-based plasma mass spectrometry confirmed the preservation of authentic biogenic signals despite the effect of spatially restricted diagenetic overprint. The Sr/Ca record of faunal remains is in line with expected trophic positions, contextualizing fossil hominid diet. Pongo sp. displays marked seasonal cycles with ~3 month-long strongly elevated Sr/Ca peaks, reflecting contrasting plant food consumption presumably during the monsoon season, while lower Sr/Ca ratios suggest different food availability during the dry season. In contrast, omnivorous H. erectus shows low and less accentuated intra-annual Sr/Ca variability compared to Pongo sp., with δ13C data of one individual indicating a dietary shift from C4 to a mix of C3 and C4 plants. Our data suggest that H. erectus on Java was maximizing the resources available in more open mosaic habitats and was less dependent on variations in seasonal resource availability. While still influenced by seasonal food availability, we infer that H. erectus was affected to a lesser degree than Pongo sp., which inhabited monsoonal rain forests on Java. We suggest that H. erectus maintained a greater degree of nutritional independence by exploiting the regional diversity of food resources across the seasons.

Seasonal dietary niche changes in Neotropical bats

Abstract In the vast Neotropic seasonal environment, the most diverse family of bats, the Phyllostomidae (leaf-nosed bats), includes up to 93 species. As the quality and quantity of food resources fluctuate in the habitats, diet heterogeneity is observed among bat species and regions of the Neotropics. In this study, we investigated by faecal analyses, how the dietary niche (DN) of eight Phyllostomidae bat species (Artibeus planirostris, A. fimbriatus, Carollia brevicauda, C. perspicillata, Chiroderma villosum, Glossophaga soricina, Platyrrhinus lineatus, and Sturnira lilium) that occur in a karstic area in the Midwest region of Minas Gerais, Brazil, change in response to seasonal food availability. We recorded the consumption of insects and nine plant families. Moraceae was the most frequent, followed by Piperaceae. Given that seasonal dietary changes can be subtle and hardly noticeable along with fluctuating habitat conditions, we performed the DN decomposition of the eight bats species into subniches, by analysing the data with the WitOMI, which is a decomposition of the niche into temporal subniches. By improving the accuracy and details of the results, we assessed the effects of abiotic (precipitation and environmental temperature) and biotic (quantity and quality of food resources) interactions within the phyllostomid bat community. For each species, we compared niche breadth and overlap and found higher values for the dry season among morphologically similar species. The results of our study suggest that ecologically similar bat species coexist occupying different DNs.

Modeling a localized metropolitan food system in the Midwest USA: Life cycle impacts of scenarios for Des Moines, Iowa

Food systems are energy-intensive, causing ≈25 % of anthropogenic global warming potential (GWP) and contributing to challenges across the food-energy-water nexus. The state of Iowa, USA, is of particular interest as a rainfed agricultural region of the upper Midwest; despite its highly productive landscape, a large proportion of food consumed by Iowa residents is imported. This study focused on the Des Moines Metropolitan Statistical Area (DM-MSA), a six-county area in central Iowa with a 2020 population of ≈700,000. A life cycle assessment approach was used to quantify environmental impacts (GWP, fossil energy and water consumption, land use); scenarios modeled provision and consumption of 50 % of nutritional requirements for the current DM-MSA population by food group (e.g., grains, proteins, vegetables). The four DM-MSA food system scenarios were: 1) current conditions (baseline), 2) local production for 50 % of food, 3) consumption changed to follow USA dietary guidelines, and 4) combined changes to production and consumption. Localizing food production reduced all environmental impacts more than following USA dietary guidelines. Compared to the baseline, 50 % local production scenarios reduced GWP and energy consumption (18–24 %) and water use (35–41 %) annually. Decreases by food group were least for protein (−10 % GWP) and greatest for fruits and vegetables (−58–62 % GWP). Local scenario alternatives could further reduce some environmental impacts if paired with a nutritionally- and environmentally-optimized diet (EAT-Lancet) providing the greatest change (−30–38 % for GWP and energy use) compared to the local scenario. A 50 % local production scenario for the DM-MSA could decrease GWP by 102 million CO2eq yr−1 and water use by 44 billion L yr−1. However, this would require dietary changes based on seasonal food availability. Further development and co-simulation with other metropolitan-scale biophysical and social models will enhance understanding of food system drivers and support effective decision-making for urban food system improvements in the Midwest.

Conceptualizing multi-level determinants of infant and young child nutrition in the Republic of Marshall Islands-a socio-ecological perspective.

The East and Pacific region includes 14 Pacific Island Countries where, between 2000 and 2016, indicators of stunting, wasting, and micronutrient deficiencies have plateaued or worsened, while rates of overweight, obesity, and associated disease have risen. The Republic of Marshall Islands (RMI) is no exception: maternal and child nutrition indicators have not improved in decades. A study of the contemporary factors shaping the RMI nutrition situation was needed for informing policy and tailoring interventions. This formative study had an iterative design utilizing qualitative methods. An exploratory Phase 1 included 59 semi-structured interviews with community members, 86 free lists with caregivers, 8 participatory workshops, and 20 meal observations (round 1). Findings were synthesized to inform a confirmatory Phase 2 where 13 focus groups, 81 pile sorts, 15 meal observations (round 2), and 2 seasonal food availability workshops were conducted. Textual data were analyzed thematically using NVivo while cultural domain analysis was conducted in Anthropac. RMI faces interrelated challenges that contribute to a lack of nutritious and local food availability, which is compounded by high food costs relative to household incomes. A decades-long cultural transition from local to processed diets has resulted in infant and young child diets now characterized by morning meals of doughnuts, bread, and ramen with tea, coffee, or Kool-Aid and afternoon meals that include rice with canned meats (e.g., store-bought chicken, hot dogs). Individual preferences for processed food imports have increased their supply. Low maternal risk perception toward nutrition-related illnesses may further explain sub-optimal diets. Improving the RMI food environment will require approaches that align with the multi-level determinants of sub-optimal diets found in this study. As the ten-year 2013 RMI Food Security Policy soon ends, study findings may be used to inform new policy development and investments for improving the nutrition situation.

The excretion of nitrogen and phosphorus and changes in nitrogen content in the Antarctic amphipod Waldeckia obesa and isopod Glyptonotus antarcticus during long-term starvation

Seasonal food availability for benthic feeders in Antarctica can influence the level of excreted metabolites, which may then be a source of N and P for autotrophs. In this study, we examined the effects of starvation of Waldeckia obesa and Glyptonotus antarcticus on the excretion of both N and P, and the chemical composition of their bodies. N-NH4 + dominated in the pool of excreted nitrogen (93% and 77% of inorganic nitrogen, and 76% and 67% of total nitrogen, for W. obesa and G. antarcticus, respectively). Reactive phosphorus dominated in the pool of excreted phosphorus (72% and 65% of total phosphorus for G. antarcticus and W. obesa, respectively). The excretion of N-NH4 + (in µmol N h−1 100 g−1) dropped from 3,687 (W. obesa) and 1,336 (G. antarcticus) in the first day to about 0.6 after 10 days of starvation (for both species). Phosphorus excretion was generally lower than that of nitrogen (on average 0.046 and 0.017 µmol P h−1 100 g−1 for G. antarcticus and W. obesa, respectively), but no clear trend appeared with N as a result of starvation. The greatest decrease in nitrogen and protein content in W. obesa was recorded on the 3rd day of starvation (nitrogen: from 1.30% to 0.93%; protein: 8.15% to 5.80%) and in G. antarcticus on the 5th day of starvation (nitrogen: from 2.22% to 1.43%; protein: from 13.86% to 8.94%). Conclusions: (i) nitrogen and phosphorus compounds released by crustaceans may be a supplementary source of biogenic salts for autotrophs, (ii) nitrates constituting approx. 20% nitrogen may be used by phytoplankton in the period of new production, (iii) starvation reduces the excretion of N and P and the content of nitrogen and protein in crustaceans.

The impact of dietary diversity and seasonality in food availability on the quantile distribution of birth size among pregnant women in rural Malawi – a cross-sectional study

BackgroundDietary diversity scores can be used as a proxy for dietary intakes and for assessment of nutrient adequacy. Studies from low-resource settings have found maternal dietary diversity scores to be associated with neonatal birth size. We here investigated the relationship between the dietary diversity score among pregnant mothers and birth size of their offspring across quantiles of the birth size variables; birth weight, length, abdominal circumference, and head circumference. We also investigated if seasonality affects birth size across different quantiles.MethodsDietary intake and anthropometric data were collected from 190 pregnant women and their neonates in rural Malawi through two agricultural seasons. Dietary data was collected using 24-hour recall interviews and was categorized into the 10-food group dietary diversity score proposed for women by the Food and Agriculture Organization. Neonatal anthropometrics were collected upon delivery at health facilities. Quantile regression analyses were used to investigate associations between dietary diversity scores and birth size, as well as between seasonality and birth size.ResultsWe found that neonatal abdominal circumference was 0.9 cm larger during the post-harvest season compared to the pre-harvest season among neonates in the 25th quantile. Birth weight was 281.4 g higher for those born during the post-harvest season in the 90th quantile. For a one-unit increase in maternal dietary diversity score, birth weight increased by 56.7 g among those in the 25th quantile and neonatal head circumference increased by 0.2 cm for those in the 70th quantile. However, these findings did not remain significant when considering the cluster effect of the neonatal anthropometric data.ConclusionsOur findings indicate that the relationship between seasonality and birth size differs across the distribution of birth size. Investigating the effect of seasonality across the distribution of birth size could be important to identify vulnerable subgroups and develop better, targeted interventions to improve maternal and child nutrition and health.

Trophic ecology of largehead hairtail Trichiurus japonicus in the South Sea of Korea revealed by stable isotope and stomach content analyses

Largehead hairtail (Trichiurus japonicus) is one of the most commercially important fishes in the western North Pacific. To identify the dietary changes across ontogeny and seasons, we investigated its stomach contents and stable isotope signatures (δ13C and δ15N) in the South Sea of Korea. The index of relative importance revealed that the dietary composition of largehead hairtail consisted mainly of Pisces (1.6%–84.8%) and Euphausiacea (3.0%–93.0%). However, the proportions of dietary items differed by season and anal length (ALs), suggesting a trophic adaptability response to seasonal food availability and size-related trophic variation, respectively. Our isotopic results showed that the largehead hairtail is placed intermediately between pelagic and benthic fishes and was more13C and15N-depleted than other carnivorous fishes, suggesting a high consumption of pelagic species. Similarly, seasonal variations were observed in the δ13C and δ15N values of the largehead hairtails (PERMANOVA,p=0.001). Interestingly, their δ13C values in spring decreased significantly with ALs (r2= 0.594,p&amp;lt; 0.001), suggesting an ontogenetic change due to the increased proportion of Euphausiacea to the nutrition of largehead individuals during this specific season. Based on a combination of stomach contents and stable isotope signatures, overall results provide new insights into the feeding characteristics of the largehead hairtail, which improves our understanding of its trophic ecology depending on season and body size.

Seasonal variations in the composition and diversity of gut microbiota in white-lipped deer (Cervus albirostris).

The gut microbiota has key physiological functions in host adaptation, although little is known about the seasonal changes in the composition and diversity of the gut microbiota in deer. In this study, seasonal variations (grassy and withering season) in the gut microbiota of white-lipped deer (Cervus albirostris), which lives in alpine environments, were explored through 16S rRNA high-throughput sequencing based on sixteen fecal samples collected from Gansu Qilian Mountain National Nature Reserve in China. At the phylum level, Firmicutes, Bacteroidota, and Actinobacteriota dominated the grassy season, while Firmicutes, Proteobacteria, and Actinobacteriota dominated the withering season. At the genus level, Carnobacterium dominated the grassy season, while Arthrobacter and Acinetobacter dominated the withering season. Alpha diversity results (Shannon: P = 0.01, ACE: P = 0.00, Chao1: P = 0.00) indicated that there was a difference in the diversity and richness of the gut microbiota between the two seasons, with higher diversity in the grassy season than in the withering season. Beta diversity results further indicated that there was a significant difference in the community structure between the two seasons (P = 0.001). In summary, the composition, diversity, and community structure of the gut microbiota showed significant seasonal variations, which could be explained by variations in the seasonal food availability, composition, diversity, and nutrition due to phenological alternations. The results of this study indicate that the gut microbiota can adapt to changes in the environment and provide the scientific basis for health assessment of white-lipped deer.

Food insecurity, a perceived barrier to healthy eating in the lake Victoria region, Kenya: findings from a qualitative study

Consumption of poor-quality diets was noted as prevalent in the Lake Victoria Region, Kenya. As a strategy to communicate desirable change and promote healthy eating in the region, a 30-member panel of policymakers and implementers developed and proposed 12 food-based dietary guidelines (FBDGs) in 2017-2018. The objective of this study was to assess barriers in adopting the proposed FBDGs amongst community members in the lowlands of Kisumu and Homa Bay counties. Qualitative, descriptive cross-sectional design was used to collect data from 72 focus-group discussions (FGD). The FGD was conducted among 216 school going children (10-13y), 216 high school students (15-18y), 207 adult males (26-74y) and 211 females (18-71y). The participants were asked to state whether the proposed FBDGs reflected their daily dietary practices? If the answer was no, the FGD participants were asked to elaborate on the perceived barriers. Each FGD consisted of 8-12 participants. The demographics of FGD participants were collected before the start of FGD sessions. All FGD proceedings were audio-recorded and transcribed verbatim. Demographic information of participants was analyzed and presented using descriptive statistics. The FGD responses were coded and analyzed based on the main code, the barriers. Barriers to healthy eating in the study area were mainly linked to low production of food, food unavailability and inaccessibility. Specific factors which contributed to the food insecurity situation included; dry and sunny weather, seasonality in food availability, limited resources to secure potential farmland with fences, gender influence on land use, high cost of food, lack of money to purchase food, low income, sale of farm produce with resultant inadequate quantities of food consumed and inappropriate meal composition. Food insecurity was a perceived barrier to healthy eating in the lowlands of the Lake Victoria region. This research suggests the need to address food systems and economic structures to improve food production, distribution, accessibility and consumption in the region. Coding was done with the aid of NVivo8 (QSR International Pty Ltd Version 8, 2008). This study was registered with the Kenyan National Commission for Science Technology and Innovation (NACOSTI/P/18/12634/22291). Key words: Healthy eating, Lake Victoria, barriers, food insecurity, food unavailability, food inaccessibility

Vaccination of household chickens results in a shift in young children’s diet and improves child growth in rural Kenya

Childhood growth faltering remains unacceptably high in sub-Saharan Africa. Rural communities dependent on household food production with limited off-farm income or liquid assets to bridge seasonal food availability are especially vulnerable. A cross-sectional survey in Siaya County, Kenya identified 23.5 and 4.8% of children under 5 y of age as stunted and wasted, respectively, using height-for-age Z (HAZ) scores to detect stunting and weight-for-height Z (WHZ) scores for wasting. Although these households are classified as living in poverty or extreme poverty with very limited off-farm income, households commonly have on-farm resources that could be developed to improve nutrition. While 95% of these households have chickens and consumption of eggs was shown to increase childhood growth by an average of 5%, the average flock size is small and constrained by high mortality due to infectious disease. We hypothesized that interventions to relieve this constraint would translate into household decisions influencing the diets and growth of children. Here, we show that vaccination of chickens against Newcastle disease has a causal impact on children’s consumption of animal source foods rich in protein and micronutrients relative to a high-carbohydrate, grain-based diet. Children in treatment households (chicken vaccination) showed overall increases in scores for both HAZ and WHZ relative to control households, benefiting both girls and boys. The findings demonstrate the impact of directing interventions at common on-farm assets managed by women in rural communities and support programs to enhance productivity at the household level.

Seasonal and interannual variability of feeding in Antarctic benthos

AbstractThe seasonal and interannual variability of feeding in 15 species of benthic marine suspension feeder was studied over 8 yr at Ryder Bay, Antarctica. Feeding was strongly seasonal in bryozoans, gorgonians, polychaetes, and dendrochirote holothurians. The winter non‐feeding period was longest in the holothurians and shortest in bryozoans. Bryozoans started feeding in late winter at very low chlorophyll concentrations, often when surface fast‐ice was still present. In hydroids and actinians, feeding tentacles were deployed continuously throughout the year, though hydroid feeding intensity declined slightly in late winter. Water column phytoplankton biomass was strongly seasonal with marked interannual variability in the timing and intensity of the bloom, driven principally by ice dynamics. Correlation across years between the start of feeding and the development of the bloom was poor, and in seasons when a dense spring bloom of benthic filamentous microalgae developed, the start of feeding in many benthic species was delayed. This study indicates that feeding in benthic marine suspension feeders in Antarctica is influenced by factors additional to the seasonal availability of food in the water column.

Energy allocation trade-offs between life-history traits in the Mediterranean sardine: an ecophysiological approach

Since 2008, there has been a major decrease in the numbers of old and large sardines in the Gulf of Lions, which has had a major effect on regional fisheries. A bottom-up process involving a shift in diet towards smaller planktonic prey has been suggested as the main driver of this development. Yet, the reproductive capacities of the sardines have not changed, suggesting potential modifications in energy allocation trade-offs. Whether this could also affect maintenance, in particular at the end of the winter reproductive period, and explain the lower adult survival and the disappearance of older individuals remains unclear. We therefore experimentally investigated the consequences of seasonal food availability (summer vs. winter) on life-history traits and energy allocation trade-offs at the individual and population levels. Our results indicate that food resources during summer had a major effect on energy reserves and growth, limiting the maximum size and body condition reached at the end of reproduction. In addition, food restrictions during growth and/or reproduction periods led to physiological costs mediated by increased oxidative damage. Mediterranean sardines did not show any ability for compensatory growth and did not appear to be capital breeders. Instead, they displayed individual differences in coping with physiological constraints and displayed various life-history strategies regardless of food availability. We highlighted 3 main individual energy allocation strategies: (1) preferential allocation to body condition or (2) to growth, or (3) simultaneous allocation to reproduction and growth. These issues are key, as climate change is expected to favour smaller phytoplankton, which might amplify the deterioration in the condition of pelagic fish.

Proboscideans on Parade: A review of the migratory behaviour of elephants, mammoths, and mastodons

The ecology and behaviour of woolly and Columbian mammoths and mastodons have been extensively studied. Despite this, their patterns of mobility, and particularly the question of whether or not they migrated habitually, remains unclear. This paper summarises the current state of knowledge regarding mobility in these species, reviewing comparative datasets from extant elephant populations as well as isotopic data measured directly on the ancient animals themselves.Seasonal migration is not common in modern elephants and varies between years. Nonetheless, non-migratory elephants can still have considerable home ranges, whose size is affected mainly by habitat, seasonal availability of water and food, and biological sex. Strontium isotope analyses of woolly mammoths, Columbian mammoths, and mastodons demonstrate plasticity in their migratory behaviour as well, probably in response to spatio-temporal variations in ecological conditions. However, biological sex is difficult to establish for most proboscidean fossils and its influence on the results of Sr analyses can therefore not be assessed. Advances in intra-tooth sampling and analytical methods for strontium isotope analysis have enabled research on intra-annual movement, revealing nomadic behaviour in all three species. Sulfur isotopes have been analysed from woolly mammoth remains numerous times, but its methodology is not yet developed well enough to inform on past proboscidean mobility in as much detail as strontium studies.The inter- and intra-individual variation in migratory behaviour in mammoths and mastodons implies that their role in the subsistence strategies of Palaeolithic people may have fluctuated as well. Further assessment of hominin-proboscidean predator-prey interactions will require a more detailed understanding of proboscidean habitual mobility in specific contexts and places. Strontium isotope studies based on multi-year enamel sequences from multiple individuals have the potential to provide this insight.

A Test of Foraging Models Using Dietary Diversity Indices for the Lomako Forest Bonobos

Optimal diet and functional response models are used to understand the evolution of primate foraging strategies. The predictions of these models can be tested by examining the geographic and seasonal variation in dietary diversity. Dietary diversity is a useful tool that allows dietary comparisons across differing sampling locations and time periods. Bonobos (Pan paniscus) are considered primarily frugivorous and consume fruits, leaves, insects, vertebrates, terrestrial herbaceous vegetation, and flowers. Frugivores, like bonobos, are valuable for examining dietary diversity and testing foraging models because they eat a variety of species and are subject to seasonal shifts in fruit availability. Frugivorous primate species thus allow for tests of how variation in dietary diversity is correlated with variation in ecological factors. We investigated measures of dietary diversity in bonobos at two research camps across field seasons within the same protected area (N’dele and Iyema) in Lomako Forest, Democratic Republic of the Congo. We compared the results of behavioral observation (1984/1985, 1991, 1995, 2014, and 2017) and fecal washing analysis (2007 and 2009) between seasons and study period using three diversity indices (Shannon’s, Simpson’s, and SW evenness). The average yearly dietary diversity indices at N’dele were Shannon’s Hʹ = 2.04, Simpson’s D = 0.82, and SW evenness = 0.88 while at Iyema, the indices were Shannon’s Hʹ = 2.02, Simpson’s D = 0.82, and SW evenness = 0.88. Behavioral observation data sets yielded significantly higher dietary diversity indices than fecal washing data sets. We found that food item (fruit, leaf, and flower) consumption was not associated with seasonal food availability for the 2017 behavioral observation data set. Shannon’s index was lower during periods when fewer bonobo dietary items were available to consume and higher when fruit was abundant. Finally, we found that optimal diet models best-explained patterns of seasonal food availability and dietary diversity. Dietary diversity is an essential factor to consider when understanding primate diets and can be a tool in understanding variation in primate diets, particularly among frugivores. Dietary diversity varies across populations of the same species and across time, and it is critical in establishing a complete understanding of how primate diets change over time.