Feeding Intensity Research Articles

Determination of β -decay feeding patterns of Rb88 and Kr88 using the Modular Total Absorption Spectrometer at ORNL HRIBF

Precise determination of ground-state feeding in the β decay of fission products is an important but challenging component in modeling reactor antineutrino flux and reactor decay heat. The Modular Total Absorption Spectrometer (MTAS) is a versatile NaI(Tl) detector array that determines the true β-decay pattern free from the pandemonium effect, including precise ground-state feeding intensities. In this paper, we report MTAS results of the β feeding intensities of Rb88 and Kr88, fission products with large cumulative yields in nuclear reactors. By comparing MTAS results with previous measurements, Rb88 provides a validation of MTAS's ability to determine ground-state feedings in β decays, while the precision of Kr88 ground-state feeding is improved when compared with the Evaluated Nuclear Structure Data File (ENSDF). The investigation of sources that contribute to β feeding branching uncertainties in MTAS experiments is discussed in detail. Lastly, the deconvolution of Rb88 decay spectra suggests that MTAS can distinguish an allowed β spectral shape from a first forbidden unique β spectral shape.1 MoreReceived 29 October 2021Accepted 15 April 2022DOI:https://doi.org/10.1103/PhysRevC.105.054312©2022 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBeta decayNuclear structure & decaysProperties59 ≤ A ≤ 89TechniquesNuclear data analysis & compilationSpectrometers & spectroscopic techniquesNuclear Physics

Effects of breed and fattening system on fatty acid and chemical composition of meat from male lambs

The purpose of this study was to examine the fatty acid and chemical composition of the Longissimus dorsi (LD) from male Tuj and Hemşin lambs reared in extensive, semi-intensive and intensive feeding systems. At the end of 90 days eight lambs from each breed and feeding system were slaughtered to determine chemical composition, and six lambs in each group were selected at random to assess fatty acid composition. Breed and feeding system interaction affected the quantities of saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA), and the atherogenic (AI), thrombogenic (TI), and nutritive value (NVI) indices. In Hemşin the ratio of PUFA to SFA was higher in lambs fed in the extensive system than those produced in the semi-intensive and intensive systems, which were similar, whereas in Tuj this ratio decreased from the extensive to semi-intensive to intensive feeding systems. The ratio of omega n-6 to omega n-3 fatty acids was lower in the extensive and semi-intensive systems than it was in intensively fed Hemşin lambs, but increased with the intensity of feeding in Tuj lambs. Intramuscular fat content was higher in Hemşin lambs than in Tuj lambs and increased with the intensity of the feeding system. Conjugated linoleic acid content (CLA) was affected by feeding system in Hemşin lambs, but not in Tuj lambs. Because of their high PUFA/SFA ratio and low TI value, Tuj lambs reared in extensive feeding system were deemed to have the best performance.

Fish feeding intensity quantification using machine vision and a lightweight 3D ResNet-GloRe network

Quantifying feeding intensity of fish is important in developing intelligent feeding control system, thus improving feed utilization rate and reducing water pollution. The current study explored a real-time, high-precision and lightweight 3D ResNet-Glore fish feeding intensity quantification network, which can accurately locate the four levels of fish feeding intensities in video stream. In this network, the lightweight GloRe module is expanded in 3D space, and the Residual block in the 3D ResNet network is modified to form the 3D GloRe module. The relational reasoning is achieved through graph convolution in the interactive space to improve accuracy of discrimination. In addition, the sliding window and the frame extraction processing of the video data significantly reduces the model parameters and the amount of calculation. Experimental results showed that the classification accuracy for four types of feeding intensity was 92.68%, which is 4.88% higher compared with that of the classical 3D ResNet network. The parameters were decreased by 46.08% and the GFLOPs decreased by 44.10%. The proposed network improved the training and recognition speed and reduced the hardware equipment requirements, which can provide a theoretical basis for subsequent feeding decisions.

Long-term dynamics of forage base and food supply for nekton in the upper epipelagic layer of the western Bering Sea. Part 2. Food supply for nekton

Interannual dynamics of feeding conditions for nekton in the upper epipelagic layer of the western Bering Sea is considered for the summer and fall seasons of 2002–2020. In the summers, daily consumption by fish and squids ranged from 0.01 to 0.10 t/km2 in the deepwater basins and between 0.01–0.38 t/km2 in the shelf area at Cape Navarin. In the falls, the consumption increased to 0.03–0.14 t/km2 in the deep-water basins, and to 0.01–0.53 t/km2 in the Navarin area. Summary in the summer-fall periods, the fish and squids consumed 2–5 % of zooplankton production (up to 5–7 % in some years) in the deep-sea basins that is rather low degree of the zooplankton resources usage. In the Navarin area, the consumption is considerably higher and is estimated as 5 % in summer and 21 % in fall season, on average. In cases of heightened nekton biomass and reduced zooplankton biomass in some years, the grazing pressure on plankton increased, in particular on euphausiids, hyperiids and pteropods, while the intensity of salmon feeding decreased, with extension the portions of nektonic food and other zooplankton groups, as arrowworms, in their diet. On the other hand, the portion of juvenile fish and squids in the salmon diet increased in cases of high abundance of this prey, too. Weak correlation was detected both between the salmon feeding and abundance of their prey and between the salmon feeding and abundance of salmons. The feeding conditions for pink salmon during their offshore migration did not determine the rate of their returns. Strong year-classes of pink salmon had large returns in conditions of either poor or rich food supply in fall season, so the feeding in fall was not important for the pink salmon survival in the ocean in winter. Feeding of other fish and squids species did not change noticeably in the years with reduced food supply. In general, abundance and species composition of plankton and nekton communities were rather stable in the western Bering Sea in the 2000-2010s, and this current state of the ecosystem provides stable functioning of nekton communities both in the deepwater and Navarin areas.

The Gut Contents of the Squalius cii in a Permanently Interrupted River System, the Karamenderes River

The goal of this study was to determine the temporal and spatial distribution of the gut contents of Squalius cii specimens in a permanently interrupted Karamenderes River. The specimens were sampled at seven distinct locations along the Karamenderes River in summer 2012, autumn 2012, and spring 2013. The gut contents of a total of 157 specimens were examined. The data on the identified food organisms were quantified as the percentage of the index of relative importance (IRI%), niche breadth (BA), trophic level (TL), feeding intensity (Vacuity Index, VI), and food diversity (H’). In all seasons, the examined specimens were found to mostly feed on the members of the Insecta family in the river's upper section and on Bacillariophyceae and macrophytes in the lower section. The feeding intensity was found to be the highest in spring 2013, while the food diversity was realized to exhibit the highest value (2.21) at the Karaköy 1 site in summer 2012. The niche breadth of the examined specimens varied between 0.01 and 0.73, whereas their trophic levels ranged between 2.01 and 3.48. The S. cii specimens were fed on high-quality foods in the upper section of the dam.

Relative Gut Length and Gastro-somatic Index of Acanthopagrus arabicus (Iwatsuki, 2013) from the Offshore Waters of Pakistan

Relative gut length, Zihler’s index, and Gastro-somatic index of Acanthopagrus arabicus were studied to investigate its feeding intensity and feeding habit, by collecting 240 samples of fishes from two fishing harbors of Pakistan from September 2017 to August 2018. According to the results, fish mean total length ranged from 16.26 ± 2.83 cm (in June) to 30.89 ± 5.16 cm (in September), and mean total weight ranged from 77.70 ± 42.25 g (in June) to 486.80 ± 237.28 g (in November). The total length and gut length of A. arabicus have a strong statistical relationship (P < 0.05). In A. arabicus, the overall relative gut length (RGL) values were ranged from 0.69 to 2.63 with a mean value of 1.57 ± 0.31. The RGL lowest (1.35) and highest (1.70) value was analyzed in the size groups ranging 12.0 - 16.0 cm TL and 24.1 - 28.0 cm TL respectively. However this value is not much greater than 1, A. arabicus could be described as an omnivorous feeding habit in coastal waters of Pakistan. The temporal changes in the feeding intensity of A. arabicus were found as the Gastro-somatic index (Ga-SI) presented a significant difference during the twelve months (ANOVA, P < 0.05). The Gastro-somatic index lowest value was found in January (1.55 ± 0.59) and highest in August (5.66 ± 3.26). This type of study is beneficial for aquaculture as well as assessing the ecological role of A. arabicus along with its position in the food chain of Pakistani coastal waters.

Effects of Artemisia dracunculus L. Water Extracts on Selected Pests and Aphid Predator Coccinella septempunctata L.

The aim of this study was to determine the effects of water extracts of tarragon (Artemisia dracunculus L.) on the feeding intensity, mortality, and weight gain of selected pests, i.e., adult pea leaf weevils (Sitona lineatus L.), nymphs, wingless females of black bean aphids (Aphis fabae Scop.), and L2 and L4 larvae of Colorado potato beetle (Leptinotarsa decemlineata Say). In addition, the effect of the tarragon extracts on the voracity of the non-target organism Coccinella septempunctata L. L3 larvae was examined. To reduce S. lineatus feeding, at least 10% dry matter (DM) extract and 20% fresh matter (FM) should be used. Tarragon water extract has strong aphicidal potential against A. fabae, with 84% mortality of nymphs at 30% FM and 78% mortality of wingless females at 10% DM after 108 h of exposure. Aphid nymphs turned out to be more sensitive to the extracts prepared from fresh tarragon than from its dry matter. They were also more sensitive than wingless females. The body weight gain of L2 and L4 larvae of Colorado potato beetle was significantly reduced through the application of 10% and 5% extracts prepared from dry matters, respectively, while extracts prepared from fresh matter turned out to be ineffective. L2 larvae were more susceptible to extracts than L4 larvae, which suggests that they should be used as early as possible in the pest season. No negative influence of the extracts used on the voraciousness of C. septempunctata L3 larvae was found.

Understanding Fish Larvae’s Feeding Biology to Improve Aquaculture Feeding Protocols

Knowing that food ingestion and digestion are processes under neuroendocrine regulation, it is important to understand how fish larvae regulate these processes, when the digestive system itself is under development. This study aimed to analyze how gilthead seabream (Sparus aurata) larval feeding incidence and intensity were affected by time, light, and water temperature, through the analysis of gut content and how this affected cholecystokinin (CCK) content. Three short-term experiments were done: (A) 27 and 42 days post-hatch (DPH) larvae were analyzed at different intervals for 80 min, after feeding; (B) 38 and 48 DPH larvae were kept under different light intensities (0, 400, 1000 lux) for 30 min; (C) 41 DPH larvae were kept at 17, 19, 25 °C for 30 min. Feeding incidence below 100% was observed for 27 DPH larvae, and for 38 DPH larvae fed at 0 lux. Feeding intensity was several fold higher at older ages. However, the number of prey in the gut was lower at 0 lux, and higher at 25 °C. Overall, no clear pattern was observed for CCK, but at older ages increasing gut content resulted in higher CCK content. In conclusion, until 38 DPH light is important for gilthead sea bream larval feeding ability, and maturing functionality of CCK was only observed at later stages.

Species-specific plant-mediated effects between herbivores converge at high damage intensity.

Plants are often exposed to multiple herbivores and densities of these attackers (or corresponding damage intensities) often fluctuate greatly in the field. Plant‐mediated interactions vary among herbivore species and with changing feeding intensity, but little is known about how herbivore identity and density interact to determine plant responses and herbivore fitness. Here, we investigated this question using Triadica sebifera (tallow) and two common and abundant specialist insect herbivores, Bikasha collaris (flea beetle) and Heterapoderopsis bicallosicollis (weevil). By manipulating densities of leaf‐feeding adults of these two herbivore species, we tested how variations in the intensity of leaf damage caused by flea beetle or weevil adults affected the performance of root‐feeding flea beetle larvae and evaluated the potential of induced tallow root traits to predict flea beetle larval performance. We found that weevil adults consistently decreased the survival of flea beetle larvae with increasing leaf damage intensities. In contrast, conspecific flea beetle adults increased their larval survival at low damage then decreased larval survival at high damage, resulting in a unimodal pattern. Chemical analyses showed that increasing leaf damage from weevil adults linearly decreased root carbohydrates and increased root tannin, whereas flea beetle adults had opposite effects as weevil adults at low damage and similar effects as them at high damage. Furthermore, across all feeding treatments, flea beetle larval survival correlated positively with concentrations of carbohydrates and negatively with concentration of tannin, suggesting that root primary and secondary metabolism might underlie the observed effects on flea beetle larvae. Our study demonstrates that herbivore identity and density interact to determine systemic plant responses and plant‐mediated effects on herbivores. In particular, effects are species‐specific at low densities, but converge at high densities. These findings emphasize the importance of considering herbivore identity and density simultaneously when investigating factors driving plant‐mediated interactions between herbivores, which advances our understanding of the structure and composition of herbivore communities and terrestrial food webs.

Nursery function of mangrove creeks in temperate climates for estuarine fish

ABSTRACT Coastal habitats are recognised for their role as nurseries for fish. However, there are conflicting results on whether fish are using mangrove habitats primarily for shelter or feeding grounds, making it challenging to generalise their ecological value for fish. The objective of this study was to investigate whether fish communities use mangroves in temperate climates as feeding grounds. Fyke nets were set during an outgoing tide to assess the fish communities found within mangrove creeks at high tide in the Austral spring and summer. Gut content analyses were conducted to assess diet, and samples were collected for prey availability (i.e. plankton, macroinvertebrates, and meiofauna). The mangrove creeks were used by small-bodied fish, including adults of small species or juveniles of larger species, which occurred in greater abundances in spring than summer. Feeding intensity (GFI) of fish was low, reflecting the low abundances of potential prey found in the mangrove creeks. This suggests that small-bodied fish may not use the mangrove creeks as potential feeding grounds. There is a possibility of fish using mangrove habitats at high tide for shelter while they rely on adjacent habitats (e.g. seagrass meadows) to feed, highlighting the relevance of habitat heterogeneity of tidal wetlands for ecosystem services.

SEASONAL CHANGES OF CHOLESTEROL IN THE TISSUES OF MALE CATFISH MYSTUS CAVASIUS (HAM) IN BHADRA RESERVOIR, KARNATAKA, INDIA

Seasonal variation in cholesterol of the different tissues of the freshwater catfish Mystus cavasius was investigated from Bhadra Reservoir. The amount of cholesterol in liver, muscle and testes was measured. A decline was recorded during the period when the gonads were passing through the peak ripe stage. The highest value of the cholesterol was however attained before this phase of gonad maturation. Concentration pattern of liver cholesterol seemed related to variations in the cholesterol metabolism of the fish, necessitated, besides other factors, by the demand for sex hormones. A possibility of the influence of feeding intensity on liver cholesterol content has also been indicated.

A predatory gastropod as the potential biological control agent of the Korean invasive mussel, Mytilus galloprovincialis (Lamarck, 1819)

The classical biological control, which is the intentional introduction of exotic species to manage the biological invasion, is the standard measure if the human-mediated management is no longer effective. This method, however, involves a latent risk that the introduced exotic species brings about the nontarget effect on indigenous native species. Applying the native natural predator is the best alternative to control the invasive alien species without the substantial change into the ecosystem of the area invaded. Here, we introduced an indigenous Korean muricid gastropod Reishia bronni (Dunker, 1860), a potential natural predator of the Mediterranean mussel Mytilus galloprovincialis (Lamarck, 1819), a well-known invasive alien species successfully settled down in Korea. In the biomonitoring survey on the Korean ports of the east coast between 2007 and 2011, we have observed the spread of R. bronni within the Mytilus galloprovincialis community. The observed decrease of the mussel density around the gastropod assemblage led us to the idea that R. bronni is the natural predator of M. galloprovincialis . In order to clarify such a predator-prey interaction between both species, we performed a field observation from two Korean ports in August 2012, keeping R. bronni and M. galloprovincialis individuals together into the cages for 18 days. Then, we counted the number of latter ones consumed and estimated the average time spent feeding per individual of R. bronni . We observed the positions of the drill holes made on the consumed shells by it. Our results showed that R. bronni is the active natural predator of M. galloprovincialis with the high feeding intensity and the unique foraging behavior targeting the lateral margin of the shell, so-called “Marginal drilling”. Therefore, we could suggest the possibility that R. bronni can be applied to control the mass spread of M. galloprovincialis .

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.

Feeding habit and diet composition of Glossogobius aureus Akihito & Meguro, 1975 in the Vietnamese Mekong Delta

Glossogobius aureus (Gobiiformes: Gobiidae) is a target fish and widely distributed in the Mekong Delta, from fresh to brackish waters. However, knowledge on its food and feeding ecology is scarce. Therefore, this research was carried out in four sampling sites along the estuarine of Hau River in order to fill this information gap. A total of 742 individual fish was collected monthly using trawl nets from January to December 2020. A combined analysis of the fullness index and Costello graph suggested that this fish species displayed high feeding intensity. The results revealed that G. aureus is a carnivore and its food composition comprised Acetes spp., Actinopterygii, zooplankton, and other preys (e.g. snails and detritus). Acetes spp. is the main food of this species. The diet composition varied with sites but not genders, fish sizes, and seasons. Acetes spp., Actinopterygii and other preys contributed to the spatial variation of food composition. The findings revealed knowledge about the fish feeding ecology, which may propose suitable foods for its aquaculture development.

Tropicalization unlocks novel trophic pathways and enhances secondary productivity in temperate reefs

Abstract The structure of ecological communities is rapidly changing across the globe due to climate‐mediated shifts in species distributions, with novel ecosystem states emerging as new species become dominant. While it is clear that such changes restructure habitat properties and their associated assemblages, how new nutritional resources and consumers may affect the ecosystem trophic structure and energetic dynamics remains poorly resolved. Here, we investigate how the reconfiguration of tropicalized reefs—that is, temperate ecosystems receiving an influx of tropical species—affects the availability of nutritional resources and energy flow through herbivore‐based trophic pathways. To do so, we quantified changes in algal and detrital resources along a tropicalization gradient in eastern Australia. We also estimated energy flow towards herbivorous fishes by quantifying their standing biomass (kg/ha), productivity (kg ha−1 day−1), and biomass turnover (% day−1), using an individual‐level modelling approach that combines estimates of fish growth rates and mortality. Along the gradient, tropicalized reefs had relatively higher amounts of palatable algal turfs and detrital particulates compared to non‐tropicalized sites. Feeding intensity by herbivorous fishes was also c. 400 times higher on tropicalized reefs, with tropical turf‐cropping surgeon fishes being responsible for >98% of the feeding rates. Turf‐driven trophic pathways underpinned virtual all (>99%) of the biomass produced by tropical fishes, which contributed up to 63% of the total herbivorous fish standing biomass and 86% of the productivity despite only representing 35% of the abundance. Turfs also fuelled most of the secondary productivity of tropical fishes on tropicalized reefs across Australia's western tropical–temperate transition zone, although their overall productivity was ~5 times lower. This is possibly due to turfs there containing elevated sediment loads, which dilute the nutritional quality of turf‐based resources, as well as other differences in the biogeographical context. We propose that algal turfs are central drivers of ecosystem energetic shifts on temperate reefs as they become tropicalized because they support novel algal and detrital trophic pathways that enhance secondary productivity and biomass turnover. Our results also suggest that turf characteristics such as organic content or sediment load may emerge as increasingly important drivers of energy flow in temperate locations where turfs dominate benthic cover. A free Plain Language Summary can be found within the Supporting Information of this article.

Food spectrum dynamics of anadromous Hilsa, Tenualosa ilisha (Hamilton, 1822) inhabiting River Brahmaputra, India curtailing apprehension of food selectivity: An insight into its domestication

Food and feeding habits of Tenualosa ilisha collected from two sampling locations in Brahmaputra River, Assam, India for a period of 12 months from May 2018 to April 2019 were studied. Index of preponderance revealed semi-digested animal matter (25.92 %) as the most dominant food item followed by Bacillariophyta (23.32 %). 31 genera of phytoplankton and 15 genera of zooplankton were observed in the gut of the species. Major groups of zooplankton include cladocerans, copepods, followed by rotifers, while diatoms, green algae and blue green algae were dominant phytoplankton groups. The anadromous tropical shad is planktivorous by nature and has a preference for zooplankton in smaller size groups (< 250 mm) and phytoplankton in larger size groups (> 250 mm). GaSI values (mean±SE) ranged from 1.50±0.14 to 6.93±0.89 and HSI values from 0.58±0.06 to 1.54±0.15. Index of fullness was found to range from 7.08±0.42 to 1.81±0.40. Feeding intensity, GaSI, HSI values showed seasonal variation, found to be low during October to December and high during February to June. Size group-wise analysis of feeding intensity showed high feeding intensity in lower size groups (< 250 mm) and comparatively low feeding intensity and high percentage of empty stomachs in higher size groups (> 250 mm). RLG values ranged from 1.181±0.028 to 1.450±0.052. Monthly average RLG values were found to be highest during November and in the size group of 351 – 400 mm. Changes in food composition were noticed in both months and as well as size groups.

Feeding habit of Brown trout (Salmo trutta fario) in upper parts of river Swat, Pakistan.

Salmo trutta fario is the most important fish species of family Salmonidae inhibited in cool waters all over the world including the nortern parts of Pakistan. This study was aimed to find out the prey selection and feeding habits of the species. One hundred and eighty five Salmo trutta fario were captured from March 2016 to April 2017. Feeding intensity as represented by a fullness index (FI), changing with various length groups and season. Out of 185 Brown trout 24 fish stomaches were found empty. The most important and common food items of brown trout were Brachycentridae, Blepharocera, Hydropsychidae, ephemerella spp. Kruskal Wallis H-test were applied on feeding intensity groups consisting of three month group. The test statistic for K.W-H-test were (H=8.13 with df =3) had a p-value of 0.043 < (alpha=0.05 indicates favor of the alternative hypothesis of at least one difference among the feeding intensity groups. The linear relationship of N with index of relative importance and %IRI denoted by least square regression line (N = 35.2 + 22.1%IRI), shows that for 22 prey there is 1% change in IRI. The relationship between total length (mm) and fish body weight (gm) is expressed by Pearson correlation coefficient (r = 0.976), showed that total length (mm) and fish body weight (gm.) is highly correlated. Descriptive statistics are used for the stomach fullness, which shows that feeding intensity was recorded higher from March to May. A total of 2289 preys was recorded including the most common were; Trichoptera, Hydropsychidae, Brachycentridae, diptera, blepharocera, ephemerala, chironomida, honey bees, grass hopper, locust, trout egg, trochanter, plant tissue, stones were retrieved from the gut contents of brown trout. According to index of relative importance IRI% four preys represents major components of the diet. The highest IRI% was recorded in Brachycentridae (39.38%), followed by blepharocera (13.23%), Hydropsychidae (10.76%) and ephemerella spp (8.28%). The relationship between IRI and FO is (r =0.556) is moderately correlated with coefficient of determination (r2=0.31). This study will help in the development of an artificial diet for the species for better growth performance in captivity.

Trophic ecology and resource partitioning of Haemulidae species along the Northeastern Brazilian continental shelf

Abstract In the Southeastern Tropical Atlantic, Haemulidae family play an important role both environmentally, acting as a link between lower and higher trophic levels, and socioeconomically, being widely caught by artisanal fleets. This study aimed to describe the trophic ecology of three grunt species (Haemulon aurolineatum, H. plumierii and H. squamipinna) considering spatial, temporal and ontogenetic aspects, integrating stomach content and stable isotopes analysis. Sampling occurred in 26 stations along the Northeast of Brazil (04°– 09°S), in August 2015 and April 2017, using bottom trawling net. There was greater feeding intensity at night, at latitudes below 08°S and in the inner continental shelf. Higher values of δ¹⁵N were reported for H. aurolineatum and H. plumierii collected near coastline. The isotopic niche breadth indicated that H. aurolineatum has a narrower diet thanH. plumierii. For the three species, the trophic level ranged between three and four. Considering stomach content and isotopic niche, diet was similar comparing species. This trophic ecology pattern reveals a likewise use of the habitat, which may be essential for identifying priority areas for conservation on an ecosystem basis, especially in rich reef zones that are subject to several increasing pressures, such as those in Northeast Brazil.

Deep-Water Japanese Blunthorn Lobster Palinustus waguensis Kubo, 1963: First Estimates of Life History Parameters From the Southwest Coast of India

Palinustus waguensis Kubo, 1963, is the deep-sea Japanese blunthorn lobster belonging to the Family Palinuridae. It is a species that has been rarely reported, living in rocky habitats on deep-reef slopes at a depth of 100–250 m. An estimated catch of 100 kg of P. waguensis consisting of 113 males, 54 females, and 23 berried lobsters were collected during the first fortnight of January 2019 from the multi-day shrimp trawls operating off Sakthikulangara, Kerala, India. The mean total length was recorded as 112.3 mm in males, 102.6 mm in females. The parameters of the length-weight relationship were estimated as, a = 0.041, b = 2.84 for males and a = 0.05, b = 2.86 for females, which were not significantly different (P &gt; 0.05, r2 &gt; 0.90) between the males and females. The relative condition factor (K) in the males and females of P. waguensis ranged from 2.07–4.96 and 1.87–3.86, respectively, attributing to the better feeding efficiency in males. Food and feeding analysis revealed the dietary content as fish (53 %), crab (23.5 %), shrimp (7.8 %), digested matter (11.6 %), and foraminifera (4 %). Feeding intensity analysis about the fullness of the stomach showed the specimens bearing full stomachs (11.3 %), three-fourth full (9.9 %). Length at 50 % maturity (Lm50) was 96.9 mm. Gonado-somatic index (GSI) ranged from 3.39 to 8.13. The present study forms the first report on the biology of the deep-water Japanese blunthorn lobster, P. waguensis from India.

The Simulation of the dynamics of 137Cs accumulation by freshwater fish

The study aimed to simulate the dynamics of 137Cs accumulation by freshwater fish under conditions of hypothetical radioactive contamination of water reservoirs in different seasons. The subject of research is the regularities of 137Cs accumulation by non-predatory fish species in eutrophic and oligotrophic water bodies. The dynamics of the 137Cs content in freshwater fish was calculated according to the content of radionuclides in water masses. The results of modeling the volumetric activity of 137Cs in water masses were used as an input parameter for the radionuclide accumulation in fish model. The fish organism was represented in the form of 3 independent related only by the balance equation; seasonal changes in the fish feeding intensity were taken into account in the modeling. The parameter that takes into account the contribution of the feeding intensity to the process of 137Cs intake into the fish organism has been determined. The features of the dynamics of 137Cs accumulation in eutrophic and oligotrophic water bodies fish are analyzed for cases of a hypothetical accidental input of 137Cs into ecosystems at the beginning of different periods of the annual life cycle of fish: 1st - from 1 to 31 March; 2nd - from 1 to 30 April; 3rd - from May 1 to September 19; 4th - from September 20 to October 19; 5th - from October 20 to November 30; 6th (freeze-up period) - from December 1 to February 28. The study has found that for a eutrophic water body the highest levels of 137Cs content in peaceful fish will be formed in the case of 137Cs entering ecosystems in spring (options 1–3). The maximum levels of 137Cs content in fish will be observed in the contamination period mentioned in option 3. Under hypothetical pollution in the autumn-winter period (options 4–6), the levels of 137Cs in peaceful fish will be approximately 2 times lower than in the case of pollution of the reservoir in spring. It has been found that the maximum value of the specific activity of 137Cs in fish from an oligotrophic water reservoir is not related to the season of pollution. However, the levels of fish pollution in the oligotrophic reservoir will be 1.5–2 times higher than those of the eutrophic one in options 1–3 and 3–4 times higher in options 4–6 . In the event of an emergency density of 137Cs fallout at the level of 4 kBq /m2 on the surface of different types of closed water reservoirs, its specific activity in peaceful fish will exceed the currently established permissible levels of fish products contamination. If the fallout density is twice as low (2kBq/ m2), the accumulation levels 137Cs by fishes of eutrophic water bodies will exceed the permissible standards in case of emergency inflows in spring. For oligotrophic water reservoirs, the guaranteed non-excess of the established standards in fish products is possible if the 137Cs fallout density is under 0.5 kBq /m2. Key words: fish, modeling, 137Cs, specific activity, hypothetical pollution, reservoirs of different trophic status.