Feeding Opportunities Research Articles

The nutrition profile and utility of banana puree as a liquid thickener for medically complex infants with dysphagia.

Dysphagia among infants, particularly high-risk and preterm neonates, poses feeding challenges that can impact multiple systemic outcomes and delay hospital discharge. Limited therapeutic options for approved thickening agents for human milk and infant formula necessitate the exploration of alternatives, including banana puree. This study investigated the feasibility of using banana puree as a thickening agent for hospitalized infants with dysphagia. The International Dysphagia Diet Standardisation Initiative (IDDSI) flow test determined optimal volumes of banana puree mixed with infant formulas or human milk to achieve desired liquid thickness levels. Nutrition analysis considered potassium intake and calories from carbohydrates to assess dietary composition. Banana puree effectively achieved IDDSI Levels 1-3, with varying volumes required based on milk types and caloric concentrations. The nutrition analysis revealed the importance of restricting banana puree to 15% of feeding volumes to avoid exceeding recommended potassium levels while promoting appropriate nutrition. Banana puree represents a promising option for thickening feeds in infants with dysphagia, facilitating safe oral feeding opportunities, accelerating the introduction of oral feeding, and, potentially, improving long-term outcomes. Further research is warranted to explore its impact on feeding progression, hospital stays, growth, patient outcomes, and feeding-related behaviors compared with traditional thickening agents.

Linear infrastructure and associated wildlife accidents create an ecological trap for an apex predator and scavenger

Animals may fall into an ‘ecological trap’ when they select seemingly attractive habitats at the expense of their fitness. This maladaptive behavior is often the result of rapid, human-induced changes in their natal environment, such as the construction of energy and transportation infrastructure. We tested the ecological trap hypothesis regarding human-created linear infrastructure on a widely distributed apex predator and scavenger—the Golden Eagle (Aquila chrysaetos), whose range spans the entire Northern Hemisphere. Roads and railways offer novel and attractive feeding opportunities through traffic-induced mortality of other species, while powerline areas provide perching or nesting sites and scavenging opportunities from electrocuted or collision-killed birds. These conditions may have negative demographic consequences for eagles if these apparent opportunities turn into traps. Using step selection functions, we analyzed habitat selection of 74 GPS-tracked Golden Eagles (37 adults and 37 immatures) during eleven years in Fennoscandia. To assess habitat attractiveness, we used wildlife traffic accident statistics for dominant wild species, and to evaluate demographic consequences, we used mortality data from the GPS-tagged eagles. Our analysis revealed that eagles selected linear features such as roads, railways and powerlines at both the population and individual levels. Both adult and immature eagles consistently selected these features, and the strength of selection for linear features increased with age in immature eagles. The linear features however had 5.5 times higher mortality risk for eagles than other selected habitats indicating the presence of an ecological trap. We discuss the implications of these findings for the conservation and population ecology of apex predators and scavengers, as well as their potential demographic consequences. To mitigate this issue, we urgently recommend the removal of carcasses from roads and tracks to prevent ecological traps for raptors and scavenger species worldwide. Additionally, we advocate for the development of methods and strategies to reduce wildlife traffic accidents.

Characterizing humpback whale behavior along the North-Norwegian coast

BackgroundStudying movement patterns of individual animals over time can give insight into how they interact with the environment and optimize foraging strategies. Humpback whales (Megaptera novaeangliae) undertake long seasonal migrations between feeding areas in polar regions and breeding grounds in tropical areas. During the last decade, several individuals have had up to a 3-month stop-over period around specific fjord-areas in Northern Norway to feed on Norwegian spring-spawning (NSS-) herring (Culpea harengus L.). Their behavioral patterns during this period are not well understood, including why some whales seemingly leave the fjords and then later return within the same season.MethodsTo investigate whale behavior during this seasonal stopover, we classified humpback whale tracks into five distinct movement modes; ranging, encamped, nomadic, roundtrip and semi-roundtrip. A behavioral change point analysis (BCPA) was used to select homogeneous segments based on persistence velocity. Then, net squared displacement (NSD) over time was modeled to differentiate movement modes. This study also manually identified longer roundtrips away from the fjords that lasted several days and examined movement modes within these.ResultsInside the fjord systems, encamped mode was most prevalent in December–January, suggesting the whales were mainly foraging on overwintering NSS-herring in this area. During the same winter seasons, half of the whales left the fjords and then returned. We hypothesize that these trips serve as ‘searching trips’ during which the whales seek better feeding opportunities outside the fjords. If better foraging conditions are not found, they return to the fjords to continue their feeding. The overall most common mode was ranging (54%), particularly seen during the start of their southwards migration and in areas outside the fjord systems, indicating that the whales mainly moved over larger distances in the offshore habitat.ConclusionsThis study serves as a baseline for future studies investigating both the searching trip theory and humpback whale behavior in general, and confirms that this method could be useful to analyze local scale movement patterns of satellite tagged whales.

Distribution and habitat use by the Audouin's Gull (Ichthyaetus audouinii) in anthropized environments

Human activities provide wildlife with highly abundant and predictable food subsidies, which can affect population dynamics and have wide-ranging ecological impacts. A key ecological question is how species adapt their foraging behaviour to capitalize on these new feeding opportunities. We investigate habitat use by Audouin's Gulls (Ichthyaetus audouinii) off the Western Mediterranean Sea, an opportunistic seabird that has recently expanded to diverse breeding colonies subjected to varying degrees of human influence. By combining GPS tracking, remote sensing, and GIS, we assessed the resource selection and habitat preferences of gulls from five colonies across their breeding latitudinal range, including interactions with industrial fisheries. Overall, the use of terrestrial habitats was slightly higher (57 % of total positions) compared to the marine environment (42 %), with individuals preferentially feeding on urban and related areas or fishing ports. However, habitat utilization varied among studied colonies, likely in response to contrasting food availability and accessibility of human related food resources on land (e.g., agriculture and livestock areas, landfills or rice fields). At sea, individuals largely distributed over highly productive and persistent marine areas with intense fishing pressure. Individuals also adapted their daily activity patterns to match food availability: gulls preferentially feed on the marine environment during the night, while the use of terrestrial habitats increases during daylight hours. Individuals' daily activity patterns also matched that for the two main fishing gears operating in the area: diurnal trawlers and nocturnal purse-seiners. Our findings offer perspectives on the reliance of opportunistic seabird species on anthropogenic food subsidies and inform on potential implications for the conservation and management of these under changes in fishing policies (EU discard ban). Broadly, we provide further insights on how this species can adapt to changing environments.

Zooplankton communities of small lakes of the Kuibyshev district Novosibirsk region in the spring and summer

In the course of hydrobiological studies conducted in the spring and summer of 2023 on small lakes of the Kuibyshev district of the Novosibirsk region, zooplankton communities were studied, which is relevant in the field of studying the fish food supply. The purpose of this study was to determine the species diversity and quantitative characteristics of zooplankton communities of lakes. Sampling and in-house processing of samples was carried out according to generally accepted methods. The characteristics of zooplanktonic invertebrates in terms of qualitative and quantitative indicators are considered. The assessment of the trophic and feeding capacity of the lakes is given. 16 species of organisms of 12 genera from 9 families were found in the zooplankton, 5 of which are rotifers, 9 are branched crustaceans and 2 are oar-footed crustaceans. It was found that the greatest species diversity was observed in Lake Tsybovo — 13, the smallest in Lake Maloe Puchkovo — 9 taxa. The average zooplankton abundance and biomass in the studied lakes ranged from 16.0 to 67.645 thousand specimens/m3 and from 652.2 to 7118.5 mg/m3, respectively. The maximum average values of zooplankton abundance and biomass were found in Lake Fedino, the minimum values in Lake Cemetery. In terms of frequency of occurrence and specific abundance, Copepods are mainly dominant. The lowest frequency of occurrence and specific abundance is mainly in Rotifera. According to the average indicators of zooplankton biomass, lakes have different trophic status and feeding capacity of the reservoir: from oligotrophic type (low-fat) to eutrophic type (high-fat). Fedino Lake was classified as a high-grade eutrophic reservoir with an increased productivity class. Cemetery Lake with the lowest abundance and biomass indicators was assessed as an oligotrophic reservoir of low productivity class, from the point of view of feeding opportunities for planktophage fish — low-feeding. Tsybovo and Maloe Puchkovo lakes were assessed as mesotrophic reservoirs.

Short-term effects of clearing restoration on the relationship of plant and moth communities

Abstract Insects and plants share a close relationship; plants provide feeding opportunities, ecological niches, and shelters for insects, while insects, in turn, facilitate pollination for plants. Management actions might positively or negatively affect insect species richness and/or abundance, in particular, forest practices can significantly influence insect communities. In this study, we investigated the effects on plant and moth communities following the realization of an ecological corridor (composed of 10 clearings) in forest in NW of Italy. Specifically, through plant surveys and moth light traps, we investigated plant and moth communities and their relationship in newly shaped clearings and their surrounding forest. We found that plants responded quickly to clearing formation, presenting differentiated plant communities between xero-thermophile clearings, mesophile clearings and forest. These differences reflected on moth communities as well, allowing to find indicator species for each ecosystem. Structural variables (i.e. openness) and topography (i.e. elevation) were key factors affecting the differentiation of moth communities. On the other hand, plants explained most of the variance in moth communities, so, through plants, we differentiated moth communities into those typical of xero-thermophile clearings, mesophile clearings and forest. In conclusion, forest management significantly affects plant and moth communities. Newly shaped clearings support higher species richness (including specialist species) and abundance than closed canopy forest. To increase species richness and abundance for both plants and moths, we suggest conservation measures that include creating open habitats within forests at medium elevation (650–950 m a.s.l.).

Restorative function of offshore longline mussel farms with ecological benefits for commercial crustacean species

Offshore ocean aquaculture is expanding globally to meet the growing demand for sustainable food production. At the United Kingdom's largest longline mussel farm, we assessed the potential for the farm to improve the habitat suitability for commercially important crustaceans. Modelled distribution patterns (GAM & GLM) predicted the low complexity seabed beneath the mussel farm was 34–94 % less suitable for European lobster (Homarus gammarus) and brown crab (Cancer pagurus) than nearby rocky reefs. The mussel farm operations, however, contributed large amounts of living mussels and shell material to the seabed. Acoustic telemetry revealed that H.gammarus remained within the farm for between 2 and 283 days using both the farm anchors and areas of seabed dominated by fallen mussels for refuge. In contrast, C. pagurus movements showed no affinity to either the farm infrastructure or benthic habitat under the farm. Stable isotope analysis indicated a high dietary niche overlap in C. pagurus and H. gammarus (67.8 and 84.6 %) between the mussel farm (mixed muddy sediment) and nearby rocky reef. Our mixed-methods suggest that the mussel farm augments structural complexity on the seabed providing refuge and similar feeding opportunities for lobster and crab as their typical habitat on rocky reefs. Longline mussel farms can deliver profound biodiversity-positive effects through biogenic augmentation of degraded habitat for commercial species and potential for co-benefits to local fisheries.

Disentangling the drivers of urban bird diversity in the non-breeding season: A general synthesis.

Current knowledge about the impacts of urbanisation on bird assemblages is based on evidence from studies partly or wholly undertaken in the breeding season. In comparison, the non-breeding season remains little studied, despite the fact that winter conditions at higher latitudes are changing more rapidly than other seasons. During the non-breeding season, cities may attract or retain bird species because they offer milder conditions or better feeding opportunities than surrounding habitats. However, the range of climatic, ecological and anthropogenic mechanisms shaping different facets of urban bird diversity in the non-breeding season are poorly understood. We explored these mechanisms using structural equation modelling to assess how urbanisation affects the taxonomic, phylogenetic and functional diversity of avian assemblages sampled worldwide in the non-breeding season. We found that minimum temperature, elevation, urban area and city age played a critical role in determining taxonomic diversity while a range of factors-including productivity, precipitation, elevation, distance to coasts and rivers, socio-economic (as a proxy of human facilitation) and road density-each contributed to patterns of phylogenetic and functional diversity. The structure and function of urban bird assemblages appear to be predominantly shaped by temperature, productivity and city age, with effects of these factors differing across seasons. Our results underline the importance of considering multiple hypotheses, including seasonal effects, when evaluating the impacts of urbanisation on biodiversity.

Organismal trade-offs and the pace of planktonic life.

No one is perfect, and organisms that perform well in some habitat or with respect to some tasks, do so at the cost of performance in others: there are inescapable trade-offs. Organismal trade-offs govern the structure and function of ecosystems and attempts to demonstrate and quantify trade-offs have therefore been an important goal for ecologists. In addition, trade-offs are a key component in trait-based ecosystem models. Here, I synthesise evidence of trade-offs in plankton organisms, from bacteria to zooplankton, and show how a slow-fast gradient in life histories emerges. I focus on trade-offs related to the main components of an organism's Darwinian fitness, that is resource acquisition, survival, and propagation. All consumers need to balance the need to eat without being eaten, and diurnal vertical migration, where zooplankton hide at depth during the day to avoid visual predators but at the cost of missed feeding opportunities in the productive surface layer, is probably the best documented result of this trade-off. However, there are many other more subtle but equally important behaviours that similarly are the result of an optimisation of these trade-offs. Most plankton groups have also developed more explicit defence mechanisms, such as toxin production or evasive behaviours that are harnessed in the presence of their predators; the costs of these have often proved difficult to quantify or even demonstrate, partly because they only materialise under natural conditions. Finally, all multicellular organisms must allocate time and resources among growth, reproduction, and maintenance (e.g. protein turnover and DNA repair), and mate finding may compromise both survival and feeding. The combined effects of all these trade-offs is the emergence of a slow-fast gradient in the pace-of-life, likely the most fundamental principle for the organisation of organismal life histories. This crystallisation of trade-offs may offer a path to further simplification of trait-based models of marine ecosystems.

Behavioural heterogeneity across killer whale social units in their response to feeding opportunities from fisheries.

Intra-population heterogeneity in the behavioural response of predators to changes in prey availability caused by human activities can have major evolutionary implications. Among these activities, fisheries, while extracting resources, also provide new feeding opportunities for marine top predators. However, heterogeneity in the extent to which individuals have responded to these opportunities within populations is poorly understood. Here, we used 18 years of photo-identification data paired with statistical models to assess variation in the way killer whale social units within a subantarctic population (Crozet Islands) interact with fisheries to feed on fish caught on fishing gear (i.e., depredation behaviour). Our results indicate large heterogeneity in both the spatial and temporal extents of depredation across social units. While some frequently depredated on fishery catches over large areas, others sporadically did so and in small areas consistently over the years. These findings suggest that killer whale social units are exposed to varying levels of impacts of depredation, both negative (potential retaliation from fishers) and positive (food provisioning), on their life history traits, and may explain the contrasted demographic patterns observed within the declining population at Crozet but also potentially within the many other killer whale populations documented depredating on fisheries catches worldwide.

Pinworm Blatticola blattae infection and survival of starving German cockroach Blattella germanica.

The German cockroach Blattella germanica is commonly infected with the pinworm Blatticola blattae. To determine the effect of pinworm infection on cockroach survival, we artificially altered the pinworm infection status of cockroaches and determined the number of survival days under no-feeding conditions, with and without opportunities for fecal feeding. Four lines of the German cockroach (Wn, Wp, Nn, and Np groups) were used in the experiment. Wp and Np were pinworm-infected lines. Wn and Nn were pinworm-free lines. The 50% survival days of cockroaches in the absence of opportunities for fecal feeding were not significantly different in Wp (3.45days) vs Wn (3.27), and in Np (4.60) vs Nn (4.48). In contrast, in the presence of fecal feeding, the 50% survival times for the pinworm-infected Wp (4.04) and Np (6.65) were significantly longer than those for the pinworm-free Wn (2.77) and Nn (5.46). The number of survival days without feeding was significantly higher in the pinworm-infected group given the opportunity to eat feces than in the non-infected group. These results suggest that pinworm infection of cockroaches during starvation, in association with fecal feeding, may be associated with longer survival.

Do human-wildlife interactions predict offspring hiding strategies in peri-urban fallow deer?

Human activities can induce significant behavioural changes in wildlife. Often explored through extractive interactions (e.g. hunting) that can favour certain behavioural traits, the implications of non-extractive ones, such as wildlife feeding, remain understudied. Research shows that people tend to favour bolder individuals within populations despite their dynamics and consequences being unclear. Using fallow deer in a peri-urban environment, we studied whether mothers that show reduced fear of humans and consistently approach them for food adopt weaker anti-predator strategies by selecting less concealed fawning bedsites closer to human hotspots. This would provide the advantage of additional feeding opportunities in comparison with shyer mothers while keeping their fawns close. Our dataset encompassed 281 capture events of 172 fawns from 110 mothers across 4 years. Surprisingly, mothers that regularly accepted food from humans selected more concealed bedsites farther from human hotspots, giving their offspring better protection while also benefitting from additional food during lactation. Our results show behavioural adaptations by a subset of females and, for the first time, link the tendency to approach humans and strategies to protect offspring. Given previous findings that these begging females also deliver heavier fawns at birth, our research further investigates human-wildlife feeding interactions and their behavioural implications.

Balancing risks and rewards of alternate strategies in the seaward extent, duration and timing of fjord use in contemporary anadromy of brown trout (Salmo trutta)

BackgroundAnadromy comprises a successful life-cycle adaptation for salmonids, with marine migration providing improved feeding opportunities and thus improved growth. These rewards are balanced against costs from increased energy expenditure and mortality risk. Anthropogenic-induced environmental changes that reduce benefits and/or increase costs of migration e.g., aquaculture and hydropower, may therefore result in adaptations disfavouring anadromy. We tagged brown trout (Salmo trutta) smolts (N = 175) and veteran migrants (N = 342), from five adjacent riverine populations located in Sognefjorden, the longest Norwegian fjord-system supporting anadromous brown trout populations (209 km). Over four years, 138 acoustic telemetry receivers were deployed to track migrations of tagged individuals from freshwater and throughout Sognefjorden. Detected movements were used to fit migration models and multi-state mark-recapture models of survival and movement for each life-stage. Seaward migration distance was modelled to examine the fitness consequences from alternate migration strategies, with these models used to simulate the extent of fjord-use by individuals and accompanying growth, fecundity and survival consequences. We compared these findings with mark-recapture data collected prior to aquaculture and hydropower development.ResultsThe telemetry data revealed that the outermost-fjord region was utilised by all populations albeit by few individuals. However, historical recaptures were located at a greater distance from the river mouth (87.7 ± 70.3 km), when compared to maximum migration distances of present-day counterparts (58.6 ± 54.9 km). River of origin influenced observed migratory behaviour and differential survival was estimated for each population and life-stage. The simulations based on telemetry-data models revealed a 30% and 23% difference in survival among populations for smolts and veteran migrants, respectively. At the individual-level, a long-distance migration strategy was rewarded with enhanced fecundity. However, the main contribution to population-level fecundity was overwhelmingly derived from middle-distance migrants, due to higher mortality rates and limited numbers of long-distant migrants.ConclusionsWe conclude that present-day anadromy is precarious, but potential risk varies considerably between life-stages and populations, even within a single fjord system. Our findings suggest that selection for extended migration is under pressure, we therefore stress the importance of monitoring and management actions to secure genetic variation pertinent to preserve fitness gains of anadromy.

Modeling transport and feeding of juvenile Kemp's ridley sea turtles on the West Florida shelf

Survivorship during the juvenile oceanic phase likely acts as a bottleneck on the growth of sea turtle populations, and starvation mortality through this period is one potential factor influencing year class strength. We combined a simulation of juvenile Kemp's ridley (Lepidochelys kempii) sea turtle dispersal based on an ocean circulation model with an Atlantis ecosystem model to examine the spatial overlap of young sea turtles with their prey resources. We were particularly interested in whether ocean currents facilitated the movement of juveniles from western Gulf nesting beaches to areas in the eastern Gulf along the West Florida Shelf (WFS) with adequate food availability. We found that strong frontal gradients on the WFS may increase the potential for juveniles to remain offshore in areas of high per capita prey availability, allowing for more feeding opportunities during critical early life stages. Additionally, we found that multiple climatological indices are related to Gulf-wide patterns of juvenile dispersal, potentially via effects on the Loop Current. Findings from this study hold implications for continued population viability of protected sea turtle populations in the Gulf of Mexico, as well as other species with early life stages that disperse via ocean currents such as commercially important fishes.

Sightings of Bryde's whale, Balaenoptera edeni, off the Pacific coast of Nicaragua

Abstract Here, we report the first sighting records of Bryde's whales in Nicaragua. Four sightings were made in 2022 during boat-based surveys off the southwestern coast of Nicaragua. Photo-identification, distributional data, dive times, and behavioural information were collected, and environmental parameters, including sea surface temperature, were measured for each sighting. Sightings included calf and non-calf groups displaying travelling (n = 1; 25%), milling (n = 1; 25%), and suspected feeding (n = 2; 50%) behaviours. Approximately 4 h of focal following allowed the calculation of short and long breath intervals. Based on our observations, the individuals were suspected of feeding in the area, based on the presence of feeding birds, feeding humpback whales, relatively high time-lagged chlorophyll-a, and observed general behaviours. Our findings indicate that this species may occasionally visit Nicaraguan coastal areas in search of feeding opportunities, and could represent a possible range extension of the Eastern North Pacific stock.

Nutritional guide to feeding wheat and wheat co-products to swine: a review.

Inclusion of wheat grain can offer feeding opportunities in swine diets because of its high starch, crude protein (CP), amino acid (AA), and phosphorus (P) content. High concentrations of starch within wheat grain makes it a good energy source for swine. Mean energy content of wheat was 4,900 and 3,785 kcal/kg dry matter (DM) for digestible energy and metabolizable energy, respectively. CP concentration can vary based on the class of wheat which include hard red winter, hard red spring, soft red winter, hard white, soft white, and durum. The average CP of all wheat data collected in this review was 12.6% with a range of 8.5% to 17.6%. The AA concentration of wheat increases with increasing CP with the mean Lys content of 0.38% with a standardized ileal digestibility (SID) of 76.8%. As CP of wheat increases, the SID of AA in wheat also increases. Mean P of wheat was 0.27% and median P was 0.30%. Off-quality wheat is often associated with sprouts, low-test weight, or mycotoxin-contamination. Sprouted and low-test weight wheat are physical abnormalities associated with decreased starch within wheat kernel that leads to reductions in energy. The assumed energy value of wheat grain may need to be reduced by up to 10% when the proportion of sprouted to non-sprouted wheat is up to 40% whereas above 40%, wheat's energy may need to be reduced by 15% to 20%. Low-test weight wheat appears to not influence pig performance unless it falls below 644kg/m3 and then energy value should be decreased by 5% compared to normal wheat. Deoxynivalenol (DON) contamination is most common with wheat grain. When content is above the guidance level of 1mg/kg of DON in the complete diet, each 1mg/kg increase in a DON-contaminated wheat-based diet will result in a 11% and 6% reduction in ADG and ADFI for nursery pigs, and a 2.7% and 2.6% reduction in ADG and ADFI, in finishing pigs, respectively. Wheat co-products are produced from the flour milling industry. Wheat co-products include wheat bran middlings, millrun, shorts, and red dog. Wheat co-products can be used in swine diets, but application may change because of differences in the final diet energy concentration due to changes in the starch and fiber levels of each wheat co-product. However, feeding wheat co-products are being evaluated to improve digestive health. Overall, wheat and wheat co-products can be fed in all stages of production if energy and other nutrient characteristics are considered.

European plaice movements show evidence of high residency, site fidelity, and feeding around hard substrates within an offshore wind farm

Abstract Offshore wind farms (OWFs) are expanding rapidly in the North Sea, often creating spatial conflicts with fisheries. Managing such conflicts requires knowledge on the impact of OWFs on the spatial distribution and movement behaviour of fished species. However, such knowledge is still lacking, especially for soft sediment fish such as flatfish, which are vital fisheries resources in the region. Therefore, we used acoustic telemetry to examine the spatial behaviour of European plaice in relation to an OWF and its structures. In a small study area (1.37 km2), we observed high residency for plaice around the turbines and scour protection layer (SPL), which consists of large rocks around the turbine foundation. The fish primarily resided on sandy sediments near the hard substrates, but showed a diurnal pattern of proximity to the turbine, being closer during the day. Considering their trophic ecology, these findings suggest that plaice moves towards the SPL for feeding opportunities on the hard substrate, potentially leading to increased ecological fish production within OWFs. Although most plaice moved away from the OWF in winter, likely towards spawning grounds, many exhibited high site fidelity returning to the study area after the winter migration. OWFs thus offer protection from fishing mortality as “closed” feeding grounds in spring and summer, but not during winter spawning migrations, which may result in spillover effects. These insights should inform local fisheries management in relation to plaice movement within and around OWFs.

Bergmann patterns in planktivorous fishes: A light‐size or zooplankton community‐size rule is just as valid explanation as the temperature‐size rule

AbstractAimBergman patterns, the tendency of organisms to be larger at higher latitudes and lower temperatures, are a well‐studied biogeographic pattern. Yet, there is no consensus on the driver or underlying mechanisms. We aim to scrutinize the influence of several key proposed drivers of Bergmann patterns (temperature, seasonal light availability, prey size and seasonal abundance) on optimal body size in planktivorous fishes across high latitudes in the Northeast Atlantic.LocationNortheast Atlantic between 55 and 75° N, with implications for high‐latitude oceans globally.Time periodPresent day.Major taxa studiedPelagic planktivorous fishes, with Atlantic herring (Clupea harengus) as model organism.MethodsWe use a model that incorporates explicit mechanisms for vision‐based feeding and temperature‐dependent physiology of a planktivorous fish to explore how intrinsic and extrinsic constraints affect energy budgeting and thereby expected optimal body size based on bioenergetics. We run the model at latitudes with increasing seasonality and test the individual and joint effects of relevant drivers.ResultsA Bergmann pattern emerges from the interaction between visual feeding opportunities and temperature‐dependent physiology. Small individuals profit from faster energy processing at higher temperatures in the south, whereas large individuals benefit from a lower metabolic cost at colder temperatures and more daylight hours for feeding in the north. In isolation temperature, daylight hours, and prey size each produced Bergmann patterns, but the most pronounced pattern arose from all drivers combined.Main conclusionsStudying biogeographic body size patterns requires a holistic view, accounting for interactions between drivers and both intrinsic and extrinsic constraints on energy budgeting. Across latitudes, temperature effects on digestion and metabolism interact with effects of light availability, prey size and abundance on food accessibility, and thereby shape the optimal size. Our study highlights how details of ecological mechanisms and lifestyles are important for improving predictive ability.

What is behind the success of terrestrial bromeliads as microhabitat for the sylvatic triatomine Mepraia spinolai?

Puya alpestris, P. berteroniana and P. chilensis (Bromeliaceae) are terrestrial plants present in north-central Chile, considered important part of the shrub flora due to their abundance and close interaction with animals. A previous study showed that bromeliad cover positively correlates with the abundance of the sylvatic triatomine vector Mepraia spinolai, only when infected by the protozoan Trypanosoma cruzi, the etiological agent of Chagas disease. Here, we assessed the biological interactions and abiotic conditions provided by these Puya species to M. spinolai. During the austral summers of 2015 and 2016, we sampled 17 sites with presence of M. spinolai colonies. In each site, we estimated the presence of bromeliad and its cover proportion, and placed a camera trap for three months near a M. spinolai colony to record the vertebrates potentially interacting with this triatomine. Three of the camera traps were placed right in front of M. spinolai-colonized bromeliads. At the same time, triatomines present under these bromeliads were collected to assess their blood meal by Next Generation Sequencing. Between July 2017 and January 2018, we examined the abiotic conditions (temperature and humidity) under bromeliad, under rocks and at ground level. We detected 40 vertebrate species associated to Puya spp. (18 birds, 16 mammals, and 6 reptiles). Puya spp. are a resource for keystone species in T. cruzi sylvatic transmission, including small mammals (Octodon degus, Phyllotis darwini) and lizard species (Liolaemus spp.), detecting a positive association between bromeliad presence and availability of reptiles and non-domestic mammals. Native rodents and humans were the most represented vertebrates in the diet of M. spinolai collected under bromeliads. Temperatures were more stable under bromeliad, showing lower amplitude (up to 14.3 °C) compared to under rocks (23.7 °C) or at ground level (49.6 °C). Bromeliads present in the semiarid-Mediterranean ecosystem provide feeding opportunities for triatomines, and act as buffer of abiotic conditions reducing daily thermal amplitude. The presence of bromeliads near human settlements should be carefully monitored, especially because their leaves are consumed by people and browsed by livestock present in endemic areas of Chagas disease.

Implementation of the Pelagic Hotspot Index in detecting the habitat suitability area for bigeye tuna (Thunnus obesus) in the eastern Indian Ocean

Abstract. Istnaeni ZD, Gaol JL, Zainuddin M, Fitrianah D. 2023. Implementation of the Pelagic Hotspot Index in detecting the habitat suitability area for bigeye tuna (Thunnus obesus) in the eastern Indian Ocean. Biodiversitas 24: 5044-5056. Bigeye tuna (Thunnus obesus Lowe, 1839) is a species with a high economic value that can migrate horizontally and vertically over a large area. Although sea temperature has been the main focus of previous findings, other variables can serve as a reasonable proxy. Here we used sea surface chlorophyll-a, sea surface height, subsurface sea salinity, and subsurface temperature to predict the suitable habitat area for bigeye tuna in the Eastern Indian Ocean Off Java. A Generalized Additive Model was performed to analyze the best-fit model evaluated from the p-value and Cumulative Deviance Explained. The suitability index of the selected model was calculated using Pelagic Hotspot Index constructed from multi-spectrum satellite data. The results showed that the high catches were located on the high suitable index value and supported by chlorophyll-a as the most significant factor, followed by sea surface height, temperature, and salinity. This condition was stimulated by the high feeding opportunity, which may relate to the EIO's oceanic front, eddies, and specific current patterns. This study helps identify ecological hotspots, track the migration, and monitor the seasonal closure for bigeye tuna, particularly in EIO.