Fullness Index Research Articles

Feeding habits of juvenile sockeye salmon of different ages in the Kurile Lake pelagial (Kamchatka) on the data for 1967 and 1972

A study was made of the nutrition of different-sized sockeye salmon underyearlings during the littoral feeding period in the summer-autumn period of 1972 on lake and river habitats. Diet of 2and 3-year-old sockeye salmon individuals sampled in pelagic zone was analyzed also. It was found, that permanent and dominating component in the diet of the age groups 0+, 1+ and 2+ of juvenile sockeye salmon in the littoral and pelagic zones of Kurile Lake was plankton crustacean Cyclops scutifer: up to 1700 individuals per one stomach, making 33.3–99.6% of the stomach content. Juvenile sockeye salmon were feeding on the cyclops of various ontogenetic stages, the bigger were juvenule sockeye salmon individuals, the higher was the part of large copepodids of late stages, mature individuals. The other components of the diet included larval chironomids, which role was maximum in feeding of underyearlings with the body length 26–30 mm, pupal chironomids and imago aerial insects. Index of fullness of the underyearling stomach in the samples from the lake littoral and composition of the forage spectra indicated that condition of feeding were different in different habitats.

Effects of sucrose substitutes and hydrocolloids on the texture of low‐sugared orange peels as a moist filling for baked products

In this study, partial sucrose substitutes (trehalose and xylitol) and hydrocolloids (CMC-Na, guar gum, and xanthan gum) were added to low-sugared orange peels fillings. The single-factor and orthogonal tests were used to study the effect of sugars and hydrocolloids on the texture of the products. The results showed that the hardness and chewiness in the samples treated with 10% xylitol + 20% trehalose + 5% sucrose + 0.13% composite fillers achieved the soft texture, and the fullness index of samples reached 89.80%; T22 content of this treated group was significantly 91.53% higher than that of the control ones. Low-field nuclear magnetic resonance results interpreted that the water-holding capacity of sucrose substitutes and hydrocolloids maintained the water in samples during drying, thereby maintaining the soft texture. Hence, sucrose substitutes and hydrocolloids at appropriate amount have a great potential to maintain the quality of moist fillings. Novelty impact statement CMC-Na and guar gum could maintain the water of samples during dying. 10% xylitol +20% trehalose +5% sucrose +0.13% composite fillers was the best formula. Sucrose substitutes and hydrocolloids could improve the quality of moist fillings.

Observation of the feeding behaviour of reared Japanese eel Anguilla japonica leptocephali fed picocyanobacteria Synechococcus spp.

The authors observed the feeding behaviour of artificially reared Japanese eel Anguilla japonica leptocephali, 7.5-19 mm total length (10-61 days post-hatch), fed Synechococcus sp., which is considered a potential food source of anguilliform larvae. Three strains of Synechococcus sp. (NIES-972, 976 and 979) were tested as the food material. Larvae across the entire length range could effectively ingest a suspension of pico-sized cyanobacteria (1-3μm in diameter). Video observations of the mid-hindgut of larvae under an epifluorescence microscope confirmed that the movement of microvilli of the intestinal epithelium allowed the cell particles to circulate in the mid-hindgut, before becoming solidified in the anal region. Significant differences in food intake were observed between larvae fed two strains of Synechococcus (NIES-972 and 976), and among different cell densities, which suggests feeding selectivity and density dependence. Comparisons of feeding behaviour under the light group (9L:15D) and the dark group (24D) showed significantly higher food intake (measured as an index of intestinal fullness) in the light group, although substantial and continuous ingestion was observed in the dark group, indicating continuous feeding by swallowing sea water. The authors hypothesise that the feeding ecology of anguilliform leptocephali is based on a survival strategy whereby the larvae do not compete with various higher-trophic-level fishes for food in an oligotrophic environment.

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.

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.

Seasonal variations in the feeding ecology of Nephrops norvegicus in the Adriatic Sea: insights from stomach contents and stable isotope analyses

Norway lobster Nephrops norvegicus is one of the most important commercial species in the Mediterranean. This study focused on its feeding ecology in an important fishing ground within the Adriatic Sea, using an integrated approach of stomach content (SCA) and stable isotope (SIA) analyses. The simultaneous use of these tools represents a modern and complete approach that provides reliable data over time and reflects the feeding strategy of the analysed species. Monthly sampling was carried out (January-December 2019, July and October 2020; 589 specimens) to investigate seasonal changes in diet and trophic level. Variations in fullness, gonadosomatic and hepatosomatic indices were analysed to explore changes in feeding and variations in energy requirements linked to reproductive needs. Results showed that N. norvegicus mostly prey on decapod crustaceans and fish. Seasonal variations in prey consumption were likely linked to the reproductive patterns of the species. SIA results confirmed SCA findings and placed N. norvegicus at a high position within the benthic food web. Overall, considering that the Adriatic Sea represents one of the most important and productive fishing areas for Norway lobster, this study provides critical information for an effective ecosystem approach to fisheries management of this resource.

Особенности питания окуневых рыб в малом озере на водосборе Онежского озера

Fish feeding process is studied as one of the links in the transformation of the energy of a water reservoir, as one of the factors that determine the ecology of fish and make an imprint on the morphology, physiology and behavior of fish, or as one of the criteria, which help the most rationally use natural resources of the water bodies. The results of work carried out by the Northern Water Problems Institute (NWPI KarRC RAS) and Petrozavodsk State University (PetrSU) within the framework of state assignments, forecast problems and economic contractual topics on assessing the nutrition of perch species (perch, ruff) in some lakes of the Konchezero group (South Karelia), in particular Lake Munozero, which is part of the lower reaches of the river Shuya belonging to the catchment area of Lake Onega. The work was carried out by the experts from the IWPS KarRC RAS and PetrSU in 2018-2020. Its main hydrological and ichthyological indicators have been studied. The reconnaissance fish productivity of Lake Munozero based on the development of the forage base at the present stage is estimated as 9 kg/ha. The feeding spectra of ruff and perch in the lake overlap only with respect to eggs, the ruff using eggs more actively. Predation is peculiar only to perch, while even fish whose size is less than 14 cm (the average size of the transition to predation for Karelia) hunt at a time when there is a lot of other food in the reservoir. As the perch passes to summer feeding, its diet becomes more diverse. Some benthic organisms are replaced by others, an air fraction appears, the perch's diet includes fish in summer and spring; nutrition becomes more active: the average stomach fullness index increases from 7.3 to 145.6‰.

Ontogenetic diet shifts and feeding dynamics of Trichiurus japonicus Temminck & Schlegel, 1844, off Guishan Island, Southern East China Sea

Trichiurus japonicus Temminck & Schlegel, 1844, is one of the most ecologically and economically important fish species in the waters of southern East China Sea. Species caught by trawlers operating in the surrounding waters of Guishan Island, southern East China Sea were collected regularly from March 2018 to February 2019. The stomachs of 434 hairtails ranging in total length (TL) from 100 to 1090 mm were analyzed to study their feeding habits. Diet composition and seasonal changes in prey items were analyzed over 12 months (2018–2019) to detect any feeding shifts in prey items. Feeding indices, namely Index of Relative Importance (%IRI), Gastro-somatic Index (GaSI), Empty Stomach Ratio (ESR), and Stomach Fullness Index (SFI), were calculated to determine the feeding habits, seasonal changes, and ontogenetic shifts in prey items. ESR values differed significantly across hairtail size groups. However, no significant variations were found in ESR values between the sexes and season. The diet of T. japonicus comprised fish (80.07%), shrimps (13.89%), cephalopods (0.61%), and miscellaneous items (5.43%). Benthosema pterotum was the most common prey item during the research period, followed by Myctophidae spp and Sergia lucens. The vacuity index (VI) of T. japonicus was 29.26 percent, indicating that it is a carnivore with a relatively edacious. An unidentified teleost, as well as shrimp remains, was observed in the form and was grouped as miscellaneous items. Juveniles of Trichiurus sp. were noticed occasionally in the gut, indicating the cannibalistic behavior of T. japonicus.

Gut Content Analysis of Labeo Calbasu at Different Seasons in Dekhar Haor, Sunamgonj, Bangladesh

This research was conducted to find out the seasonal (monsoon and post monsoon) variation in gut contents of Labeo calbasu from June to November, 2016 in Dekhar haor of Sunamgonj district, Bangladesh. Three orders of phytoplankton were identified from the gut content viz. Bacillariophyceae (11 genera), Chlorophyceae (9 genera), and Cyanophyceae (4 genera). Bacillariophyceae (6.98±1.61×103cell/L) were identified as the most dominant phytoplankton group. Two types of zooplankton viz. crustacean (5 genera) and rotifer (5 genera) were identified. Crustaceans (0.88±0.4×103cell/L) were identified as the dominant group among zooplankton. Feeding intensity (average index of fullness, Gastrosomatic index) was higher in the post monsoon season compared with the monsoon season. The findings concluded that L. calbasu prefers phytoplankton over zooplankton, and the plankton consumption was slightly higher in the post-monsoon season than in the monsoon season. This research is expected to be crucial in the management and conservation of endangered L. calbasu in open waters, as well as provide baseline work for future research and open the path for captive aquaculture.

THREE SPOT GOURAMI (Trichogaster trichopterus) FOOD HABITS IN THE KOMERING RIVER'S DOWNSTREAM, SOUTH SUMATERA

One of the downstream areas of the Komering River with potential for capture fisheries is Sungai Dua Village. One of the types of fish caught by fishermen in Sungai Dua is the three spot gourami (Trichogaster trichopterus). The three spot gourami fish is a type of freshwater consumption fish that has high economic value. But the fishes only rely on catches from nature. If the fishing is carried out continuously, without domestication and cultivation, it will cause a decline in the fish population. The research about the biological aspects of red-eye septic fish (Trichogaster trichopterus) which include food habits, relationship length and weight, condition factors and stomach fullness index. This research was conducted from April to June 2017. Sampling was carried out in the downstream waters of the Komering River in Sungai Dua Village, Banyuasin Regency, South Sumatra. Fish samples were analyzed at the Animal Taxonomy Laboratory, Department of Biology, Faculty of Mathematics and Science, Sriwijaya University. The determination of stations in sampling was carried out using multiple sampling methods, namely purposive sampling and quota sampling. The result of this research showed that (1) the Cyanophyta is the main food for the three spot gourami, Diatomae and Desmidiacae as a complementary food, while the additional foods are Rhizopoda, Chlorophyta, Ostracoda, and Entomostraca, (2) The growth pattern of red-eyed fish is negative allometric with a b value of -2 (b &lt;3), the increase in length is faster than the weight gain, (3) The highest condition factor value is found in the size range 6.01-7.00 cm of 23.25 gr / cm and the lowest condition factor value is in the size range 5.01-6.00 cm of 0.62 gr / cm, and (4) The highest hull fullness index value of the red eye sepat fish hull is in the size range 7.01-8.00 cm at 32.86% and the lowest hull fullness index value at the size range 8.01-9.00 cm is 2.05% .

Diet composition, feeding dynamics and proximate composition of obtuse barracuda Sphyraena obtusata (Cuvier, 1829) in the southeastern Arabian Sea

The feeding dynamics and nutritional value of obtuse barracuda, Sphyraena obtusata collected from the coastal waters of Karnataka, southeastern Arabian Sea, India, were investigated between August 2019 to March 2020. Three hundred and fifty five specimens of obtuse barracuda having 16.5–30.1 cm total length and 23.63–175.27 g total weight were analyzed. Of the analyzed stomachs, 119 stomachs (vacuity index = 33.52%) were empty. The high feeding intensity was observed during March with 32.43% fishes having full stomachs. Stomach fullness index values were significantly (p < 0.05) higher during November (2.46 ± 0.44) and March (2.46 ± 0.41). The most dominant prey item in terms of frequency (87.80%), number (57.63%), volume (91.82%), and % IRI (93.76%) was teleosts. Crustaceans and cephalopods were encountered less frequently and were represented by Acetes sp. and Uroteuthis duvauceli respectively. The high protein (21.39 ± 0.52%) and fat (1.21 ± 0.33%) content recorded during March resulted in high-energy value (102.11 ± 5.20). The information on dietary composition and nutritional value of obtuse barracuda provided in this study can be useful for sustainable management of the fish stock in the Karnataka coast. The high protein and energy content indicated that this fish may be considered as highly nutritive food for a healthy diet.

A temporal approach for morphological indices of the common sole (Solea solea Linnaeus 1758) from the coast of the Aegean Sea, Turkey

Temporal changes of the morphological indices (Relative Gut Length (RGL), Fullness Index (FI), Hepatosomatic Index (HSI), Visceral Index (VSI), Gonadosomatic Index (GSI) and Fulton condition)) in 122 (♀: 94, ♂: 19, immature: 9) common sole were evaluated. Total length-weight relationships were calculated as W = 0.085TL3.01 and W = 0.0547TL2.40 in females and males, respectively, whereby isometric growth was observed in females and negative allometric growth was observed in males. While there was no statistically significant difference was observed between the FI, HSI, Viscerosomatic Index (VSI), RGL and GSI values of both sexes, however, there was a statistically significant difference in terms of Fulton K values (P < 0.05). In addition, there are statistical differences between the sexes total lengths and the values of RGL, FI, HSI, VSI, and Fulton-K (P < 0.05), as it is discernible in their HSI and VSI index values according to the month the specimens were obtained (P < 0.05). According to the results of the analysis, it has been determined that the female common sole along the Aegean coast adjust their energy temporally and store the energy they obtain from vegetative and carnivorous feeding. Contrary to the situation seen in females, the male individuals invest in energy through omnivorous feeding, according to the diet in the active process. Based on the results, it can be stated that the VSI and HSI are both important indicators of fish condition status. The results found here may be useful in both fishery research and fishery management.

Examination of the Trexler-DeAngelis Model of Maternal Provisioning Reveals That Matrotrophy Is Costly

The evolution of matrotrophy (post-fertilization maternal provisioning to developing embryos) has been explained through several hypotheses. Trexler and DeAngelis proposed in 2003 a theoretical model that defines the ecological conditions under which matrotrophy would be favored over lecithotrophy (pre-fertilization maternal provisioning). According to this model, matrotrophy offers a selective advantage in environments with abundant and constantly available food, whereas environments with limited and fluctuating food resources should instead promote a lecithotrophic mode of maternal provisioning. This model also proposes that matrotrophy entails the consequence of leaner reproductive females and in turn shorter lifespans. In this study, we examined the Trexler-DeAngelis model using data from 45 populations of five viviparous species from the fish genus Poeciliopsis (family Poeciliidae). We used the matrotrophy index (MI) as a measure of post-fertilization maternal provisioning, and the index of stomach fullness and individual body condition (BC) as proxies for food availability. We also estimated the magnitude of fluctuations in food availability by calculating the temporal variances of these two proxies. Neither abundant nor constantly available food were associated with greater degrees of matrotrophy, which fails to support the predictions of the Trexler-DeAngelis model with respect to the ecological drivers of increased post-fertilization provisioning to embryos. Nonetheless, in all five species we observed that females with greater degrees of matrotrophy had poorer BC compared to females that provided less nutrients to embryos after fertilization. This finding is consistent with one of the expected consequences of advanced matrotrophy according to the Trexler-DeAngelis model, namely, a detriment to the nutritional status of females. Our study provides compelling evidence that gestating females experience a trade-off between post-fertilization provisioning to embryos and self-maintenance, revealing in turn that matrotrophy is a costly reproductive strategy.

Feeding habits and seasonal trophic guilds structuring fish community in the bay mouth region of a tropical estuarine habitat.

Understanding trophic relationships of fish in estuarine ecosystem is an important element for sustainable resource management. This study examined the feeding habits of 29 dominant fish species, characterized the trophic guilds, assessed the impact of season and clarified the role of diets in structuring the fish community in the mouth region of Pattani Bay, Thailand. Samples of 5792 fishes collected monthly by gillnets from March 2019 to February 2020 were used for stomach content analyses. It was found that the number of food types and fullness index differed between fish taxa (P < 0.001). Most fishes were specialist feeders feeding on specific food components and were categorized into five trophic guilds: piscivore, shrimp-fish feeder, polychaete feeder, zooplanktivore and planktivore. Six species were piscivorous, considered as apex predators, that fed almost entirely on fishes. High diet overlaps among some species (>0.6) were recorded. Not much variation in seasonal guilds was observed: four guilds in the dry season, three in the moderate rainy season and four in the rainy season. Some species remained in the same guild the whole year round, but some fishes changed seasonally. Two fish communities from different regions of the bay were segregated based on feeding habits. The inner bay community comprised mainly copepod and plankton feeders, but there were more piscivores in the deeper bay mouth area. Results from this study help us to understand the feeding habits and trophic guilds of dominant fish species at the mouth of this tropical estuarine bay.

Feeding behaviour of the sawtooth barracuda, Sphyraena putnamae (Jordan and Seale, 1905) along the southeastern Arabian Sea, India

The food and feeding habits of the sawtooth barracuda, Sphyraena putnamae, from the southeastern Arabian Sea, India, were studied from 1367 specimens having a fork length range of 16.5–76 cm. The sawtooth barracuda consumed diverse prey items, which were grouped into three categories: teleosts, molluscs, and crustaceans. Teleosts were the preferred and dominant food component, while molluscs and crustaceans constituted the secondary and accessory food items, respectively. The chief constituents of the teleost group on basis of their dominance were identified to be carangids, scombrids, engraulids, leiognathids, and synodontids. The empty stomach ratio and stomach fullness index did not differ significantly between the sexes. The juveniles of both sexes exhibited a significantly higher stomach fullness index compared with the adults. A clear ontogenetic shift in the feeding pattern was observed, with only the crustaceans forming the diet in lower size class (<20 cm) being gradually replaced by molluscs and teleosts by medium-sized fishes (30–60 cm) and teleosts alone in the gut of S. putnamae above 65 cm. This study provides essential baseline information on the feeding habits of the Sphyraena putnamae, the first of its kind in the region. The study will be useful in understanding the trophodynamics of the species for proposing suitable management and conservation measures.

Diet composition of Oreochromis niloticus from selected impoundments of different states, with special focus on toxigenic cyanobacteria identified using molecular techniques

The diet of Oreochromis niloticus from hypereutrophic Lake Chivero and oligo-mesotrophic Lake Kariba was studied in 2017, with focus on the consumption of cyanobacteria. Water and fish were sampled to investigate the relationship between water quality and the diet of 131 fish using microscopy methods. Thirty-six fish were sampled in the second sampling phase to determine the presence of toxin producing cyanobacteria in their stomach contents using PCR methods. Lake Chivero had higher conductivity values, phosphates and total phosphorus levels while temperature and transparency were lower than those recorded in Lake Kariba. Lake Kariba recorded significantly higher water temperatures in June, October and December than Lake Chivero (p<0.05). Cyanobacteria, Microcystis spp. and Cylindrospermopsis sp. dominated in Lake Chivero and Lake Kariba water respectively. Lake Chivero fish were 0.491 times more likely to have empty stomachs than fish from Lake Kariba. Microcystis spp. had the highest relative abundance in fish stomach contents for both lakes and months. Percent relative abundance of Microcystis spp. ranged from 96.51% to 100% for fish from Lake Chivero and 46.74% to 100% for Lake Kariba fish. Stomach fullness index and abundance of cyanobacteria in the stomach contents were influenced by water oxygen percent, dissolved oxygen and temperature, transparency and phosphates for fish from Lake Chivero. For Lake Kariba fish, the stomach fullness index and abundance of cyanobacteria were influenced by total phosphorus, temperature, phosphates, transparency and chlorophyll a. Qualitative molecular analysis of the stomach contents showed the presence of potentially toxin producing cyanobacteria, Microcystis spp., in stomachs of fish from both Lake Kariba and Lake Chivero.

Microplastic pollution in perch (Perca fluviatilis, Linnaeus 1758) from Italian south-alpine lakes

Microplastic particles (MPs) contamination of aquatic environments has raised a growing concern in recent decades because of their numerous potential toxicological effects. Although fish are among the most studied aquatic organisms, reports on MPs ingestion in freshwater environments are still scarce. Thus, there is still much to study to understand the uptake mechanisms, their potential accumulation among the food webs and their ecotoxicological effects. Here, MPs presence in the digestive system of one of the most widespread and commercially exploited freshwater fish, the perch (Perca fluviatilis, Linnaeus 1758), was investigated in four different south-alpine lakes, to assess the extent of ingestion and evaluate its relation to the body health condition. A total of 80 perch specimen have been sampled from the Italian lakes Como, Garda, Maggiore and Orta. Microplastic particles occurred in 86% of the analysed specimens, with average values ranging from 1.24 ± 1.04 MPs fish−1 in L. Como to 5.59 ± 2.61 MPs fish−1 in L. Garda. The isolated particles were mainly fragments, except in L. Como where films were more abundant. The most common polymers were polyethylene, polyethylene terephthalate, polyamide, and polycarbonate, although a high degree of degradation was found in 43% of synthetic particles, not allowing their recognition up to a single polymer. Despite the high number of ingested MPs, fish health (evaluated by means of Fulton's body condition and hepatosomatic index) was not affected. Instead, fullness index showed an inverse linear relationship with the number of ingested particles, which suggests that also in perch MPs presence could interfere with feeding activity, as already described for other taxa.

Research on a Rice Counting Algorithm Based on an Improved MCNN and a Density Map.

The thousand grain weight is an index of size, fullness and quality in crop seed detection and is an important basis for field yield prediction. To detect the thousand grain weight of rice requires the accurate counting of rice. We collected a total of 5670 images of three different types of rice seeds with different qualities to construct a model. Considering the different shapes of different types of rice, this study used an adaptive Gaussian kernel to convolve with the rice coordinate function to obtain a more accurate density map, which was used as an important basis for determining the results of subsequent experiments. A Multi-Column Convolutional Neural Network was used to extract the features of different sizes of rice, and the features were fused by the fusion network to learn the mapping relationship from the original map features to the density map features. An advanced prior step was added to the original algorithm to estimate the density level of the image, which weakened the effect of the rice adhesion condition on the counting results. Extensive comparison experiments show that the proposed method is more accurate than the original MCNN algorithm.

Big eyes can't see microplastics: Feeding selectivity and eco-morphological adaptations in oral cavity affect microplastic uptake in mud-dwelling amphibious mudskipper fish

Microplastic contamination is a widespread global problem. Plastic pollution in the oceans has received a lot of news coverage, but there is a significant gap in our knowledge about its effect in estuarine areas and a profound regional bias in available information. Here, we estimated the degree of microplastic pollution, its impact on a selected fish, and its function as a vector for heavy metals in the Ulhas River estuary, which is one of the most fragile, polluted, and anthropogenically impacted estuaries in India. Using mudskipper fish, we have also assessed how the feeding guild and ecomorphological adaptations in the feeding apparatus affected the microplastic intake and life history traits of the fish. Sediment, water and fish samples were collected from three sampling localities (S1, S2 and S3) in the Ulhas River estuary and analysed. Findings showed an increase in microplastic abundance from S1 (suburban) to S3 (urban industrial belt) in sediment (96.67–130.0 particles kg−1), water (0.28–0.41 particles L−1) and fish (3.75–6.11 particles per fish). Fragments, followed by pellets and filaments largely contribute to the plastic morphotypes in sediment and water. FTIR analysis revealed polymers of anthropogenic and industrial origin such as polypropylene, Surlyn ionomer, low-density polyethylene, and polyethylene or polybutylene terephthalate. Only filaments were found in the guts of 74% of the mudskippers examined, which may be due to their filter-feeding habit and unique anatomical arrangement of oral structures that effectively filter large microplastic particles. Microplastic abundance showed a strong negative correlation with condition factor, fullness index and hepatosomatic index of fish. SEM-EDS analysis revealed that the microplastic surface topography played an important part in adsorbing heavy metals from a water body containing these contaminants. Results highlight the contamination of vulnerable estuarine habitats, harmful effects on resident biota, and health threats to dependent populations.