Feeding Habits Research Articles

Temperature and body size affect movement of juvenile Atlantic cod (Gadus morhua) and saithe (Pollachius virens) at nearshore nurseries.

Seasonal migrations of marine fish between shallow summer feeding habitats and deep overwintering grounds are driven by fluctuations in the biotic and abiotic environment as well as by changes in the internal state. Ontogenetic shifts in physiology and metabolism affect the response to environmental drivers and may lead to changes in migration timing and propensity. In this study, we investigated the effect of temperature and body size on migration timing and depth distribution in acoustically tagged Atlantic cod, Gadus morhua, and saithe, Pollachius virens, during the period of seasonal migration from shallow summer habitats. The results from our study revealed a wide range of horizontal and vertical distribution of age 1 and 2 G. morhua within the fjord. Larger G. morhua inhabited deeper, cooler waters than smaller juveniles, likely reflecting size-dependent thermal preferences and predation pressure. Conversely, juvenile P. virens occupied primarily shallow waters close to land. The variation in depth distribution of G. morhua was mainly explained by body size and not, against our predictions, by water temperature. Conversely, the dispersal from the in-fjord habitats occurred when water temperatures were high, suggesting that seasonal temperature fluctuations can trigger the migration timing of P. virens and larger G. morhua from summer habitats. Partial migration of small juvenile G. morhua from in-fjord foraging grounds, likely influenced by individual body condition, suggested seasonal migration as a flexible strategy that individuals may use to reduce predation and energetic expenditure. Predation mortality rates of tagged juveniles were higher than previously suggested and are the first robust predation mortality rates for juvenile G. morhua and P. virens estimated based on acoustic transmitters with acidity sensors. The results have relevance for climate-informed marine spatial planning as under the scenario of increasing ocean temperatures, increasing summer temperatures may reduce the juveniles' resource utilization in the shallow summer nurseries, resulting in lower growth rates, increased predation pressure, and lower chances of juvenile winter survival.

Which birds have the most to lose? an analysis of bird species’ feeding habitat in changing Australian landscapes

Australia has lost vast areas of its natural vegetation through agriculture and urbanization, resulting in the area of suitable habitat for many Australian bird species being greatly diminished. Given the geographical and ecological biases in anthropogenic land use, the impact of habitat loss now and into the future may be disproportionately high for some species, threatening their long-term persistence. Such changes are occurring rapidly, and habitat loss needs to be monitored dynamically to prevent extinction. To monitor changes in available unmodified species habitat, we use species’ area of feeding habitat (AFH), which represents the area of habitat within a species’ range with vegetation matching their feeding requirements. We analysed the past, current and future threats of habitat modification for 467 Australian bird species by calculating AFH across three time periods: pre-colonization, current (2020), and a projected future scenario (2100). These values were used to identify species subject to substantial habitat loss due to urbanization and agriculture and delineate predictors of such losses. Most species had experienced habitat loss since colonization (n = 442, 95%), and species that had already experienced considerable habitat loss were more likely to lose habitat into the future. Species with particular habitat associations (e.g., Mallee), were also more prone to greater proportions of habitat lost. The results highlight the utility of AFH and emphasize the importance of protecting what habitat remains for the species with highly depleted geographic ranges, noting that those that have experienced the most loss of unmodified habitat are the most likely to lose more unmodified habitat under future conditions.

Macro‐anatomical investigations on the skeleton of the Egyptian hedgehog (Hemiechinus auratus aegyptius)

AbstractThe skeletal anatomy of wild animals plays a major role in their adaptation to their habitats. Information regarding the skeletal architecture of the Egyptian long‐eared hedgehog (Hemiechinus auratus aegyptius), a terrestrial and nocturnal insectivorous mammal, was lacking. Current work described the detailed bone formation of this species' skeleton grossly and morphometrically. Skeletons of five adults, apparently healthy hedgehogs of both sexes, aged 10 ± 2 months, were obtained. Preparation of the bones was accomplished by using a hot water maceration procedure. The skull was elongated. The external sagittal crest and temporal lines were unclear. The mental foramen was ventral to P2. The angular process of the mandible was large. The vertebral formula was C7, T13, L6, S3, Ca 13–15. The transverse foramen was absent in the seventh cervical vertebra. The sternum was formed of five sternal segments. There was a supratrochlear foramen on the distal part of the humerus diaphysis, connecting the radial and the olecranon fossae. The radius and ulna were fused by connective tissue. The carpals had three bones in the proximal row and four bones in the distal row. There were five metacarpals with five digits. The acetabulum was circular and had deep acetabular fossa. The foramen obturatum was ovoid. The pelvic symphysis was confined only to the ischium. The greater trochanter of the femur was lower than the level of the femoral head. The trochanteric fossa was deep and oval. Tibia and fibula fused distally. Two tarsals were in the proximal row and four in the distal row. There were five metatarsals with five digits. These findings provide the anatomical basis for understanding the adaptation mechanisms of this hedgehog species to their feeding habits and habitats and aim to help veterinarians, taxonomists, and wildlife biologists' in future biomedical and comparative skeletal anatomical studies.

Anatomical and Surface Electron Microscopic Investigation of the Tongue and Laryngeal Prominence in the Red-Eyed Turtle Dove (Streptopelia semitorquata, Rüppel 1837).

This study investigated the morphology of tongue and laryngeal structures in red-eyed dove and related it to feeding habits. Samples were examined using gross anatomy, scanning electron microscopy (SEM), and histological techniques. The tongue conformed to the shape of the lower beak, and the apex with a pointed tip, body, and root were distinguished. A median grove was apparent, and a papillary crest with pointed triangular papillae separated the body from the root. The length of the tongue, its width (body), and the percentage of the length of the lower jaw occupied by the tongue were, on average, 12.5 mm, 2.3 mm, and 57.3%, respectively. SEM showed highly desquamated dorsal epithelium with pointed papillae-like projections. The papillary crest presented pointed papillae of about 20-22. Salivary openings were apparent in the root, surrounded by mucosal folds and blunt papillae. Laryngeal prominence was irregularly triangular shaped and elevated. The rim of the glottis showed glandular pinpointed marks. Typical cornified multilayered mucosal epithelium was present in the apex and decreased caudally. Hyaline entoglossal cartilage and adjoining connective tissue were present in the body and apex. Numerous tubuloalveolar glands were seen in the body and root. The rim of the glottis showed mucous intraepithelial glands. The rostral and caudal lingual glands indicated positive reaction to neutral and acidic mucins. This study demonstrated a morphofunctional relationship of the tongue of a red-eyed dove to its diet.

Spatial structure and potential processes linking fish and benthic communities in a protected reef ecosystem in SE Brazil

Top-down and bottom-up processes can mediate the structuring of biological communities. Several studies have provided separate support for those processes in pelagic and benthic compartments of reef systems but studies focusing on whole-reef processes are less common. Here, we sampled 3 ‘reef compartments’ in the Alcatrazes Archipelago in Southeastern Brazil: benthic cover of colonial organisms, solitary organisms, and reef fish (i.e. pelagic) to identify the groups responsible for spatial community structure among reefs. A dynamic mosaic structure best defines the assemblages of each compartment, with substantial changes observed among sites over 2 consecutive years and at 2 depth strata, separated by a sharp thermocline. Changes in benthic cover of colonial organisms are largely due to the extent of the blooming of Sargassum canopies, algal turfs, and the zoanthid Palythoa caribaeorum. Solitary organisms show a consistent monotonic change in the abundance of sea urchins, ascidians, and snails. Fish assemblage structure differed among reefs; however, we observed that large invertivore fish tended to concentrate in warmer water above the thermocline and small fish of different feeding habits were found in deeper and colder water in all reefs. We observed a potential strong link between the reefscape and solitary organisms, with a negative relationship between the abundance of urchins and the cover of Sargassum spp. suggesting top-down control. A second link is indicated by a positive relationship between low-lying cover composed of articulated turf and P. caribaeorum and larger invertivorous fish, suggesting bottom-up control through the provision of favorable foraging grounds.

Deep dive into the feeding habits of chinstrap penguins

Deep dive into the feeding habits of chinstrap penguins

An update for Halyomorpha halys (Stål, 1855) (Hemiptera, Pentatomidae) distribution in Belgium

The brown marmorated stink bug, Halyomorpha halys, represents an important insect pest and subsequently an important agricultural threat due to its polyphagous feeding habits and adaptability to diverse climates. Native from East Asia, its recent establishment in various regions, including North America and Europe, has led to substantial yield losses and economic impacts, which highlight the need for comprehensive research efforts, based on data occurrence by combining those from expert entomologists and citizen scientists. We reported here 14 new occurrences of this insect pest in the three regions of Belgium. Then, these data were merged with data occurrences from other studies and GBIF datasets of Belgium. The combined dataset showed a peak of presence of Halyomorpha halys in October and a dominance of field observations from citizen scientists especially in the nothern part of Belgium, Flanders. Crowd-sourced data have provided valuable insights into the presence and distribution of Halyomorpha halys in Belgium. Given the importance of the generated dataset, it could be asserted that this pest is uniformly distributed across the entire country, which necessitates additional research to evaluate its impact on various crops.

Tyramine-Mediated Hyperactivity Modulates the Dietary Habits in Helicoverpa armigera.

Helicoverpa armigera exhibits extensive variability in feeding habits and food selection. Neuronal regulation of H. armigera feeding behavior is primarily influenced by biogenic amines such as Tyramine (TA) and Octopamine (OA). The molecular responses of H. armigera to dietary challenges in the presence of TA or OA have yet to be studied. This investigation dissects the impact of OA and TA on H. armigera feeding choices and behaviors under non-host nutritional stress. It has been observed that feeding behavior remains unaltered during the exogenous administration of OA and TA through an artificial diet (AD). Ingestion of higher OA or TA concentrations leads to increased mortality. OA and TA treatment in combination with host and non-host diets results in the induction of feeding and higher locomotion toward food, particularly in the case of TA treatment. Increased expression of markers, prominin-like, and tachykinin-related peptide receptor-like transcripts further assessed increased locomotion activity. Insects subjected to a non-host diet with TA treatment exhibited increased feeding and overexpression of the feeding indicator, the Neuropeptide F receptor, and the feeding regulator, Sulfakinin, compared with other conditions. Expression of sensation and biogenic amine synthesis genesis elevated in insects fed a non-host diet in combination with OA or TA. Metabolomics analysis revealed a decreased concentration of the feeding behavior elicitor, dopamine, in insects fed a non-host diet containing TA. This work highlights the complex interplay between biogenic amine functions during dietary stress and suggests the role of tyramine in feeding promotion under stressed conditions.

Comparative mitochondrial genomics in Nematoda reveal astonishing variation in compositional biases and substitution rates indicative of multi-level selection

BackgroundNematodes are the most abundant and diverse metazoans on Earth, and are known to significantly affect ecosystem functioning. A better understanding of their biology and ecology, including potential adaptations to diverse habitats and lifestyles, is key to understanding their response to global change scenarios. Mitochondrial genomes offer high species level characterization, low cost of sequencing, and an ease of data handling that can provide insights into nematode evolutionary pressures.ResultsGenerally, nematode mitochondrial genomes exhibited similar structural characteristics (e.g., gene size and GC content), but displayed remarkable variability around these general patterns. Compositional strand biases showed strong codon position specific G skews and relationships with nematode life traits (especially parasitic feeding habits) equal to or greater than with predicted phylogeny. On average, nematode mitochondrial genomes showed low non-synonymous substitution rates, but also high clade specific deviations from these means. Despite the presence of significant mutational saturation, non-synonymous (dN) and synonymous (dS) substitution rates could still be significantly explained by feeding habit and/or habitat. Low ratios of dN:dS rates, particularly associated with the parasitic lifestyles, suggested the presence of strong purifying selection.ConclusionsNematode mitochondrial genomes demonstrated a capacity to accumulate diversity in composition, structure, and content while still maintaining functional genes. Moreover, they demonstrated a capacity for rapid evolutionary change pointing to a potential interaction between multi-level selection pressures and rapid evolution. In conclusion, this study helps establish a background for our understanding of the potential evolutionary pressures shaping nematode mitochondrial genomes, while outlining likely routes of future inquiry.

Associations between intestinal lactic acid bacteria species and feeding habits of zoo animals.

Aim: Lactic acid bacteria are among the most important bacteria in the intestinal flora and often have beneficial effects on the host. It is known that the bacteria that compose the intestinal flora are influenced by the feeding habits of host animals, but there was a lack of knowledge about lactic acid bacteria. Therefore, also considering the use of select strains as probiotics, this study investigated the relationship between the feeding habits of zoo animals and intestinal Lactobacillaceae species. Methods: Lactic acid bacteria belonging to the family Lactobacillaceae were isolated and identified from the feces of 20 zoo animal species (5 carnivores, 4 herbivores, 7 piscivores, and 4 omnivores). Isolates were identified by the homology of the 16S rRNA gene sequence. In addition, the fecal flora of host animals was evaluated by the 16S rRNA gene amplicon sequencing. Results: The types of Lactobacillaceae species were shown to vary depending on the feeding habits of host animals. Ligilactobacillus salivarius (L. salivarius) and Ligilactobacillus saerimneri (L. saerimneri) were isolated from the feces of carnivores. Whereas Ligilactobacillus equi (L. equi), Limosilactobacillus gorillae, Ligilactobacillus hayakitensis and L. salivarius were isolated from the feces of herbivores. These Lactobacillaceae species were not found in the feces of piscivores. Instead, Enterococcus were frequently found in piscivores. The fecal flora also differed according to the feeding habits of host animals; at the phylum level, Bacillota was predominant in all animals; on the other hand, herbivores tended to have a higher proportion of Bacteroidota than carnivores, and piscivores tended to have a higher proportion of Proteobacteria. Conclusion: Lactic acid bacteria differ among animal species in a manner dependent on the hosts' feeding habits.

The morphology of the branchial skeleton of heterocongrines (Anguilliformes: Congridae) and its relation to their diet

Members of the subfamily Heterocongrinae (Congridae) are a peculiar group of anguilliform eels that construct sandy borrows, form large colonies, and are popularly recognized as garden eels. They live with most of their bodies inside self-constructed borrows exposing their heads and trunk to feed on zooplankton, preferably copepods, that are brought passively by currents. As plankton feeders there was a suspicion that their branchial skeleton would have structures that could aid in the filtering process, such as highly developed or modified branchial rakers, which are observed in other suspension-feeding fishes, such as anchovies and sardines. Branchial rakers, however, were considered to be absent across Anguilliformes (except for Protanguilla). Nonetheless, specimens that were examined using clearing and staining and computed tomography showed, in all cases, branchial rakers associated with their gill arches. Heterocongrines have branchial rakers across their first to fourth branchial arches. These rakers are conical and apparently unossified, but further studies are necessary to attest its degree of ossification or its complete absence. Their pharyngeal tooth plates are reduced, a condition that may reflect their preference for smaller food items. Additionally, they may use crossflow filtering to feed, although detailed studies are necessary to clarify if hydrosol sieving may also aid in food capture. Furthermore, the present study proposes that the presence of branchial rakers should be better investigated in Anguilliformes with similar feeding habits as heterocongrines, considering that these structures may be more widespread within the group than previously considered.

A video object segmentation-based fish individual recognition method for underwater complex environments

Currently, aquaculture methods tend to combine scale and intelligence, which saves manpower and improves the survival rate of seafood at the same time. High-precision and high-efficiency fish individual recognition can provide key technical support for fish disease detection, feeding habits, body condition, etc. In the realm of intelligent aquaculture, it provides robust data support for precision fish farming. However, the current research methods for individual fish recognition struggle to maintain the network model's focus on the fish body in real marine underwater complex environments (e.g., environmental background interference such as coral reefs, overlap between fish bodies, light noise, etc.), leading to unsatisfactory recognition results. To this end, this paper proposes a method for fish individual recognition in underwater complex environments based on video object segmentation, which consists of three parts, including a fish individual segmentation detection module, a fish individual recognition module, and an all-in-one visualization module. The work adopts a combination of deep learning methods and video object segmentation algorithms to solve the problem of low attention and poor detection accuracy of fish individuals in real underwater complex environments, which effectively improves the accuracy and efficiency of fish individual recognition, and analyzes and discusses the comparison of recognition effects using different weights. The results of the simulation experiments show that the key metric Rank1 value of the method achieves more than 96% accuracy on the public datasets DlouFish, WideFish, and the Fish-seg dataset produced in this paper, and improves over the state-of-the-art methods for fish individual recognition by 2.23%, 1.33%, and 1.25%, respectively.

Po-210 in plankton and fish from coastal waters (gulf of Trieste, northern Adriatic Sea)

The activity concentrations of Po-210 were determined in seawater (<0.45 μm), suspended particulate matter (0.45–20 μm), fractionated plankton (20–50 μm, 50–200 μm, >200 μm) and tissues from four fish species, namely European seabass (Dicentrarchus labrax), Golden grey mullet (Chelon auratus), Gilt-head bream (Sparus aurata) and Common pandora (Pagellus erythrinus), collected in the Gulf of Trieste (northern Adriatic Sea). The activity concentration of Po-210 in seawater varied from 0.4 to 2.2 mBq/L in the dissolved phase (<0.45 μm) and from 0.4 to 0.8 Bq/L in suspended particulate matter (0.45–20 μm). Plankton fractionation showed the levels of 62–395 Bq/kg Po-210 in the >200 μm mesoplankton fraction, 65–459 Bq/kg in 50–200 μm and 52–537 Bq/kg in 20–50 μm microplankton fractions. No significant differences were found between fractions. The Po-210 distribution trend in fish tissues was in order: liver > stomach with intestine > kidney > spleen > gonads > gills > muscle. Bioaccumulation factors were determined for fish tissues indicating that the amount of Po-210 mostly depends on fish feeding habits. Hence, the main pathway entry of Po-210 is through ingested food. The highest estimated average total annual effective ingestion doses of Po-210 are obtained via the consumption of Common Pandora (7.1 μSv/year to 16.5 μSv/year) while the lowest doses are due to the consumption of European seabass (0.32 μSv/year to 0.76 μSv/year). Comparison with levels reported for other Mediterranean and Atlantic areas showed that only activitiy concentrations of Po-210 in fish appear significantly different, most likely because different fish species were analysed. The human dose exposure via fish consumption in the area is rather low.

Environment-Mediated Vertical Transmission Fostered Uncoupled Phylogenetic Relationships between Longicorn Beetles and Their Symbionts.

The Coleoptera Cerambycidae (longicorn beetles) use wood under different states (living healthy, freshly snapped, completely rot, etc.) in a species-specific manner for their larval diet. Larvae of some Cerambycidae groups have mycetomes, accessory organs associated with the midgut that harbor fungal symbiont cells. The symbionts are thought to improve nutrient conditions; however, this has yet to be shown experimentally. To deduce the evolutionary history of this symbiosis, we investigated the characteristics of the mycetomes in the larvae of longicorn beetles collected in Japan. Lepturinae, Necydalinae, and Spondylidinae are the only groups that possess mycetomes, and these three groups' mycetomes and corresponding fungal cells exhibit different characteristics between the groups. However, the phylogenetic relationship of symbiont yeasts does not coincide with that of the corresponding longicorn beetle species, suggesting they have not co-speciated. The imperfect vertical transmission of symbiont yeasts from female to offspring is a mechanism that could accommodate the host-symbiont phylogenetic incongruence. Some Lepturinae species secondarily lost mycetomes. The loss is associated with their diet choice, suggesting that different conditions between feeding habits could have allowed species to discard this organ. We found that symbiont fungi encapsulated in the mycetomes are dispensable for larval growth if sufficient nutrients are given, suggesting that the role of symbiotic fungi could be compensated by the food larvae take. Aegosoma sinicum is a longicorn beetle classified to the subfamily Prioninae, which does not possess mycetomes. However, this species contains a restricted selection of yeast species in the larval gut, suggesting that the symbiosis between longicorn beetles and yeasts emerged before acquiring the mycetomes.

Redescription of Semisulcospira reticulata (Mollusca, Semisulcospiridae) with description of a new species from Lake Biwa, Japan

Semisulcospira Boettger, 1886 is a freshwater snail genus divergent in Lake Biwa, Japan. Although recent taxonomic studies of the genus have arranged taxonomic accounts of many species in the lake, our knowledge of morphological traits has still been insufficient in S. reticulata Kajiyama &amp; Habe, 1961, which belongs to the S. niponica-group in the genus. Among the various habitats of the lacustrine species, in addition, the species richness of this group in coastal sandy mud areas of the lake has not been completely clarified. In this study, we revisited the taxonomic account of S. reticulata and described a new S. niponica-group species, S. nishimuraisp. nov., from Lake Biwa by evaluating the genetic and morphological relationships within the group. The reconstructed maximum likelihood and singular value decomposition quartets trees, and ADMIXTURE analyses using genome-wide SNP data strongly supported the genetic distinctiveness of most S. niponica-group species. The Random Forest classification showed that S. reticulata possesses a unique, large protoconch without distinct keels, and that S. nishimuraisp. nov. is characterized by a small, less elongated teleoconch and tiny protoconch. The large protoconch of S. reticulata and the narrow radulae of S. reticulata and S. nishimuraisp. nov. suggest their specialization in life history and feeding habits, respectively. The discovery of the new species from sandy mud substrates highlights niche differentiation among Semisulcospira species, and provides new insights into the diversification of the genus in ancient lakes.

Essential and Non-Essential Elements Levels in Fish Species Highly Consumed in the Middle Miranda River, Brazilian Pantanal.

The present study investigated the levels of As, Ag, Al, Ba, Cd, Cr, Cu, Fe, Hg, Mn, Pb, Se, and Zn in muscle samples of six fish species (Pygocentrus nattereri, Serrasalmus marginatus, Mylossoma duriventre, Leporinus friderici, Pimelodus argenteus, and P. pantaneiro) highly consumed by local riverine and non-resident people in middle Miranda River, southern Brazilian Pantanal. Significant differences were detected for Ba, Fe, Mn, and Zn levels among the analyzed species. Pairwise comparison detected significant differences in element levels between species with similar diets, which implies that other factors, instead of species' feeding habits, could be involved in distinct levels of element bioaccumulation. Significant correlations between body size and concentrations were found for Ba in P. nattereri (moderate positive correlation), and for Mn in M. duriventre (weak positive correlation) and P. argenteus (moderate negative correlation). Levels exceeding tolerable daily intake (TDI) were found for Pb maximum concentrations in P. nattereri, M. duriventre, L. friderici, P. argenteus, and P. pantaneiro, and for Cd maximum concentration in P. argenteus. Health risk assessment indicated considerable risk only for the worst-case scenario (calculated from maximum concentrations) for all species. Adopting a Pb monitoring program in biotic and abiotic compartments in Miranda River is strongly recommended.

Age, growth and feeding habit of Watases lanternfish Diaphus watasei (Pisces: Myctophidae) in the East China Sea

Age, growth and feeding habit of Watases lanternfish Diaphus watasei (Pisces: Myctophidae) in the East China Sea

Ecological dynamics and conservation implications of Indo-Pacific Tarpon (Megalops cyprinoides) in Lake Siombak, North Sumatra, Indonesia

This study presents a comprehensive examination of the Indo-Pacific Tarpon (IPT) population in Lake Siombak, North Sumatra Province, Indonesia. Through a year-long investigation, we analyzed various facets of IPT ecology, encompassing population structure, growth dynamics, reproductive behavior, feeding habits, and mortality parameters. Male dominance in collected specimens, coupled with consistently immature gonads in females, suggests a unique reproductive pattern influenced by the brackish nature of Lake Siombak. Utilizing the von Bertalanffy method, we determined a moderate growth rate in IPT, with a predominance of medium-sized, sexually immature individuals. The dietary analysis revealed an omnivorous nature, with a notable reliance on zooplankton, particularly Cladocera and Copepods. However, the most significant concern arises from the estimation of the exploitation rate (E), surpassing the annual optimum exploitation threshold, indicating a state of overexploitation. This underscores the urgent need for regulatory measures to ensure the sustainability of IPT resources in Lake Siombak. Our findings contribute to a nuanced understanding of IPT ecology in this specific ecosystem, emphasizing the importance of balanced conservation and management practices. The documented reproductive, growth, and feeding patterns provide crucial insights for informing targeted conservation strategies and safeguarding the enduring viability of the IPT population in Lake Siombak. This research serves as a foundational contribution to the broader field of fisheries science, advocating for evidence-based management to preserve the ecological balance of aquatic ecosystems.

Hydro-ecological modelling of a hypersaline lagoon ecosystem (Pulicat) in Southeast coast of India

Climate change impacts the coastal lagoons and can affect various species reproductive cycles, feeding habits, and survival. Due to natural factors, the ecosystem habitat at Pulicat Lagoon on the east coast of India is under severe stress. This study assesses the ecosystem using a numerical model and field-collected physical, chemical, biological, and meteorological data for 2018 and 2019. A coupled hydro-ecological model was used to analyze circulation features, biological and chemical interactions, and transformation processes. The study indicates that high abnormalities in the lagoon ecosystem are caused by less exchange of fresh/coastal water from river sources and sea mouths due to less rainfall during the study period. The model output depicts the salinity variation from 15 to 58 PSU in different seasons of 2018 and 2019. Furthermore, high concentrations of Chl-a ranged from 50 μg/L to 95 μg/L during the monsoon and post-monsoon seasons, triggering phytoplankton C (70–350 mg/m3) and zooplankton C (9–43 mg/m3) at the Lagoon, resulting in an algal bloom. The monsoonal shift of Chlorophyte (9.52%–9.68%), Cyanobacteria (13.22%–14.95%), Diatoms (66.08%–63.87%), and Dinoflagellates (11.18%–11.51%) is observed in the biological field, with Diatom showing the highest abundance (65%). As a result, appropriate scenario-based model studies were conducted to conserve and strengthen the ecosystem during such extreme events. The model studies suggest that widening the lagoon inlet (800m) with a depth of 5 m (3 km length) increases the optimal tidal exchange to the ecosystem. The model output demonstrates the optimal exchange that normalizes the salinity from 12 to 34 PSU from the inner Lagoon to the mouth region. This study will support environmental authorities in conserving the ecosystem through proper management adaptations.

Glycerol supplementation in farmed fish species: A review from zootechnical performance to metabolic utilisation

AbstractGlycerol, an abundant by‐product of biodiesel production, has gained attention due to its price and availability for potential commercial applications, and thus utilisation as an animal feed ingredient. This article comprehensively reviews glycerol utilisation in fish and its potential as a dietary ingredient for aquaculture. While dietary inclusion of glycerol may offer cost‐effective energy and metabolic intermediates, studies report inconsistent results regarding its effects on nutrient digestibility, zootechnical performance, and product quality. Recent studies however have demonstrated that dietary glycerol supplementation in fish induces metabolic shifts, such as alterations to gluconeogenesis and/or lipogenesis, modifying energy utilisation. Additionally, glycerol has been proposed to reduce protein catabolism, minimising nitrogen excretion and its environmental impact, but its influence on protein retention remains uncertain. Nevertheless, it is important to carefully consider the balance between feed palatability and these potential metabolic alterations when incorporating glycerol in aquafeeds. This review highlights the need for more studies to expand our understanding of glycerol metabolism in fish, since it does not seem to be metabolised by carnivorous species as much as omnivorous. Future research should explore the effects of glycerol supplementation on fish with different feeding habits and in developmental stages, as well as diverse environmental salinities and temperatures. Insight into the impact of impurities and the optimisation of glycerol inclusion in aquafeeds are recommended to support sustainable aquaculture practices and the utilisation of glycerol as a valuable resource.