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The effect of different feed rations on RAS-based pikeperch juveniles' growth parameters was studied. Juvenile pikeperch were reared in three separate experiments (I, II, and III) at a temperature of 24 °C with initial body weights of the fish at 1.3, 9.4, and 25.6 g, respectively. Four applied feed rations increased by 0.5% in each experiment: 3.0, 3.5, 4.0, and 4.5% of body weight per day (BW day−1) in experiment I; 2.0, 2.5, 3.0, and 3.5% BW day−1 in experiment II; 1.0, 1.5, 2.0, and 2.5% BW day−1 in experiment III. Each experiment in triplicates lasted 28 days. The fish were reared in tanks with working volumes of 1.0 m3 each. All experiments were performed in the same recirculating aquaculture system. The stocking density in experiments I, II, and III was 800, 400, and 200 individuals per tank, respectively. The results of experiment I showed the highest specific growth rate (SGR), weight gain (WG), and biomass gain at the feed ration of 4.5% BW day−1 (P < 0.05). In experiment II, feed ration from 2.5 to 3.5% BW day−1 showed the highest final weight (P < 0.05). In experimental III, feed ration of 2.0 and 2.5% BW day−1 showed the highest final weight, SGR, and WG (P < 0.05). Only in experiment III, based on SGR and WG, second-order polynomial regression showed that the optimal feed ration for pikeperch was 2.35–2.39% BW day−1. [ABSTRACT FROM AUTHOR]

Penaeus vannamei Boone is an important economic species in aquaculture. It has become the main species of shrimp cultured in China due to its fast growth rate, high yield, and delicious meat. Segmented culture, which is important for promoting the environmental adaptation of shrimp, reducing the negative impact of diseases and improving the success of culture, is considered one of the major methods of shrimp farming. The intermediate cultivation stage is an important stage of shrimp farming as it determines the success or failure of economic benefits. P.vannamei are usually reared in intensive aquaculture systems that are highly dependent on bait feeding, which makes optimizing feeding rates fundamental to obtaining farming benefits. The feeding rate is the amount of bait as a percentage of the body mass of the cultured object, which is an important factor affecting the shrimp factory farming. Feeding rate directly affects the survival and specific growth rate of the cultured species; an excessively slow feeding rate will slow the growth of cultured objects and affect the normal development, while an excessively high feeding rate will increase the cost of breeding and cause accumulation of residual bait, which reduces water quality and may even result in death of the cultured objects. Therefore, it is necessary to determine the appropriate feeding rate to improve baiting efficiency and to satisfy the needs of sustainable aquaculture. However, in the intermediate cultivation stage, the determination of feeding rates relies on farming experience and lacks a scientific basis. To the best of our knowledge, few scholars have analyzed the influencing mechanisms of different feeding rates on shrimp growth, physiology, and water environment separately from the perspectives of exogenous and endogenous factors; however, there is a lack of comprehensive studies on the combined effects of feeding rates. Therefore, there is an urgent need to elaborate on the intrinsic connections between different parameters, such as the growth and physiological indicators of P.vannamei, water quality, as well as the microbial communities in the culture environment. The main objectives of this study are (1) to analyze the effects of different feeding rates on water quality conditions, microbial community structure, non-specific immunity indicators, and the growth performance of shrimp during the intermediate cultivational stage; (2) to elucidate the interaction between feeding rates and different indicators; and (3) to determine the appropriate feeding rate of the intermediate cultivation of P.vannamei.In this study, three groups of feeding rates, namely T5 (5%), T7.5 (7.5%), and T10 (10%), were used to feed P.vannamei during the intermediate cultivation stage for 30 d. The effects of different feeding rates on water quality, microbial community structure, non-specific immune indices, and growth performance in the intermediate cultivation of P.vannamei were analyzed. During the experiment, water quality and shrimp growth were regularly tested, and pH, salinity, temperature, and dissolved oxygen were maintained in a range suitable for shrimp growth. At the end of the experiment, the hepatopancreas of shrimp was used for non-specific immunity activity testing, and the microbial community characteristics of different culture densities were analyzed using high-throughput sequencing technology (Illumina MiSeq). Results showed that the concentrations of total ammonia nitrogen (TAN), NO2–-N, and chemical oxygen demand (COD) gradually increased as the experiment continued, and significant difference could be observed at the end of the experiment, T10 > T7.5 > T5 (P < 0.05). Analysis of the microbial community structure showed an increasing tendency in richness and diversity with increasing feeding rates. At the phylum level, Proteobacteria (50.36%–67.53%) and Bacteroldota (12.09%–67.53%) were dominant in all samples; at the genus level, the relative abundance of Vibrio (harmful to P.vannamei) was the highest at T10 (37.33%) and lowest at T5 (0.13%), while the relative abundance of Pseudoalteromonas (beneficial to P.vannamei) was the highest at T7.5 (9.78%) and lowest at T10 (0.28%). Results of the redundancy analysis showed that the microbial community in the culture water with a feeding rate of 5% was positively correlated with salinity and temperature, and salinity had greater effect on microbial communities than temperature. The microbial community with feeding rate of 7.5% and 10% was positively affected by TAN, COD, and pH, and the effect of TAN on microbial community was greater than that of COD and pH. The superoxide dismutase, catalase, alkaline phosphatase, and acid phosphatase activities were the highest in T7.5 and were the lowest in T10 (P < 0.05). The final average weight and length of T7.5 and T10 were significantly greater than those of T5 (P < 0.05), while there was no significant difference between T7.5 and T10 (P > 0.05). Survival rate was the highest at T5 (83.12%) and lowest at T10 (68.52%), with a significant difference (P < 0.05). Factor analysis showed that the highest overall score of 0.92 was achieved at T7.5. This study showed that a feeding rate of 7.5% could improve growth performance and non-specific immunity in P.vannamei, and T7.5 was recommended for the intermediate cultivation of P.vannamei. This study elucidated the interactions between feeding rates and different indicators and determined the appropriate feeding rate for the intermediate cultivation of P.vannamei. This study might help optimize the feeding rates for the intermediate cultivational stage with a view to providing technical guidance for the improvement of the success rate of P.vannamei.

Macrophytes and cladocerans represent the main antagonistic groups that regulate phytoplankton biomass; however, the mechanism behind this interaction is unclear. In laboratory conditions, we separately evaluated the effects of three submerged macrophytes (Ceratophyllum demersum, Myriophyllum aquaticum, and Stuckenia pectinata), as well as their exudates, and plant-associated microbiota (POM < 25 µm) + exudates on the population growth of Daphnia cf. pulex and Simocephalus cf. mixtus. Living Ceratophyllum, exudates, and POM < 25 µm + exudates exhibited the most robust positive effects on Simocephalus density and the rate of population increase (r). Subsequently, we examined the effects of Ceratophyllum on the filtration and feeding rates of Simocephalus and Daphnia, revealing significant (p < 0.001) promotion of filtration and feeding in Simocephalus but not in Daphnia. To elucidate the specific effects of this macrophyte on Simocephalus demography, we assessed selected life table variables across the same treatments. The treatments involving exudates and living Ceratophyllum resulted in approximately 40% longer survivorship and significantly (p < 0.01) enhanced fecundity. Our findings indicate that exudates from submerged macrophytes positively influence Simocephalus demography by increasing filtration rates, survivorship, and fecundity. This synergy suggests a substantial impact on phytoplankton abundance. [ABSTRACT FROM AUTHOR]

Increasing rates of biological invasions pose major ecological and economic threats globally. The pet trade is one major invasion pathway, and environmental change could mediate the successful establishment and impact of these released or escaped non-native species (NNS). Salinity regime shifts are a pervasive but often overlooked environmental change in aquatic ecosystems. This study investigates the establishment and impact risks posed by three readily available, traded snail species – Melanoides tuberculata, Tarebia granifera and Anentome helena – by assessing their survival and feeding responses across a spectrum of salinity levels (0.2–16 g/kg). Survival differed among the species, with M. tuberculata showing close to 100% survival across the salinity range, T. granifera exhibiting heightened mortality at 16 g/kg, and A. helena displaying no survival at salinities above 12 g/kg. In feeding experiments assessing the more resilient M. tuberculata and T. granifera, the former had greater consumption rates towards both plant- (spinach) and animal-based (daphniid) resources. While salinity and density effects did not affect animal consumption, they both had significant effects on plant consumption, with feeding suppressed for both consumers under a salinity of 8 g/kg relative to freshwater conditions. When combining proportional survival and resource consumption for M. tuberculata and T. granifera, M. tuberculata demonstrated higher impact potential towards both plant and animal resources, highlighting its potential to exert higher ecological impacts. Studies have overlooked the importance of salinity for invasion success and the impact of pet trade species. We therefore propose that these methods provide a screening tool to assess the potential risks of traded species establishing and exerting impacts, and we encourage future studies to account for a broader range of abiotic stressors. [ABSTRACT FROM AUTHOR]

One of the most vulnerable impacts of climate on aquaculture is abnormally low temperature. The present study aimed to evaluate the effects of different feeding rates on physiological responses of Tra catfish (Pangasianodon hypophthalmus) exposed to hypothermal stress. The experimental diets were fed to triplicate groups of fish (initial weight of 6.77 g) with four feeding rates (2%, 3%, 4% and 6% of wet body weight) in a recirculation system for 4 weeks. After the feeding trial, rearing water temperature was lowered from 30 ℃ to 23 ℃ and maintained at 23 ℃ for 24 h. Fish fed 6% diet exhibited higher (p

Nutrient acquisition through heterotrophy is critical for the health of reef-building corals. The optimization of exogenous nutrition protocols to support a diversity of aquaculture corals requires improved techniques to assess feeding rates. Here, we compared the feeding rates of three coral species (Acropora millepora, Pocillopora acuta and Galaxea fascicularis) fed Artemia salina through capture rate (indirect) and dissection (direct) approaches, with direct detection and enumeration within dissected polyps facilitated by fluorescent microbeads ingested by the Artemia. When A. millepora was provided Artemia at 3 individuals ml−1 for one hour, the calculated capture rates (0.7 ind. polyp−1 h−1) overestimated prey ingested compared to prey detected directly within polyps (0.2 ind. polyp−1 h−1), and ingestion varied significantly between genotypes. In contrast, for P. acuta, capture rate calculations (1 ind. polyp−1 h−1) underestimated prey detected within polyps (3.5 ind. polyp−1 h−1) and ingestion did not vary between genotypes. For G. fascicularis, the feeding rates were similar as calculated by both capture rates (59 ind. polyp−1 h−1) and by polyp dissections (75 ind. polyp−1 h−1). Results from this study provide valuable insights into coral feeding rates of different coral species that can improve prey enrichment and feeding strategies for nutritional supplementation of corals in captivity. [ABSTRACT FROM AUTHOR]

Macrophytes and cladocerans represent the main antagonistic groups that regulate phytoplankton biomass; however, the mechanism behind this interaction is unclear. In laboratory conditions, we separately evaluated the effects of three submerged macrophytes (Ceratophyllum demersum, Myriophyllum aquaticum, and Stuckenia pectinata), as well as their exudates, and plant-associated microbiota (POM < 25 µm) + exudates on the population growth of Daphnia cf. pulex and Simocephalus cf. mixtus. Living Ceratophyllum, exudates, and POM < 25 µm + exudates exhibited the most robust positive effects on Simocephalus density and the rate of population increase (r). Subsequently, we examined the effects of Ceratophyllum on the filtration and feeding rates of Simocephalus and Daphnia, revealing significant (p < 0.001) promotion of filtration and feeding in Simocephalus but not in Daphnia. To elucidate the specific effects of this macrophyte on Simocephalus demography, we assessed selected life table variables across the same treatments. The treatments involving exudates and living Ceratophyllum resulted in approximately 40% longer survivorship and significantly (p < 0.01) enhanced fecundity. Our findings indicate that exudates from submerged macrophytes positively influence Simocephalus demography by increasing filtration rates, survivorship, and fecundity. This synergy suggests a substantial impact on phytoplankton abundance.

In Brazil, among the pesticides widely applied simultaneously in sugarcane monocultures are the Regent® 800 WG insecticide (active ingredient (a.i.) fipronil) and the DMA® 806 BR herbicide (a.i. 2,4-D). Thus, this study aimed to investigate, through different endpoints, the effects of the fipronil and 2,4-D pesticides, isolated and as mixtures, on the cladoceran Daphnia similis. To do this, acute toxicity tests were carried out with the compounds acting in isolation and in mixture, where the survival of the organisms was evaluated, and chronic toxicity tests with the isolated compounds, where reproduction and maternal and neonatal body length were evaluated. In this study, the physiological endpoints of D. similis were also analyzed, through the analysis of feeding rates (filtration and ingestion) in exposure and post-exposure scenarios, in order to verify the cladoceran food recovery capacity. In addition, D. similis data were compared with other species when exposed to the studied pesticides, using species sensitivity distribution curves. Acute toxicity tests of the fipronil and 2,4-D showed an average EC50-48 h of 66.68 μg a.i./L and 327.07 mg a.i./L, respectively. In both cases, D. similis showed lower sensitivity compared to other species. For the mixture test, the evaluation by the IA model (independent action) and deviation DR (dose ratio dependent) indicated the occurrence of mostly antagonistic effects. The chronic test with fipronil showed a decrease in the fecundity of the organism at a concentration of 16 μg a.i./L, a concentration already found in aquatic environments. For 2,4-D, no significant differences were observed for reproduction at the concentrations tested. Regarding the maternal body length, there were no significant changes when D. similis were exposed to both fipronil and 2,4-D, but these differences were observed in the body length of the neonates only for 2,4-D. There were no significant changes in the feeding rates of the organisms when exposed to both pesticides. [ABSTRACT FROM AUTHOR]

A fish species (African catfish, Clarias gariepinus) with high growth and production potential was imported from Thailand and acclimatized in the local environment of Pakistan. For the successful culture of any fish species, the knowledge about the proper feeding regime especially the appropriate amount feed offered, is very important. To determine the optimum feeding level for African catfish culture, an experiment was conducted in earthen ponds of size 0.02 hectare each, for the period of four months at a stocking rate of 10,000 fingerlings per hectare (500 fish/acre). The experiment design was CRD with four treatments (2%, 4%, 6% and 8% feeding level of wet fish body weight daily) having 3 replications. The feeding the fish at higher levels showed higher final weight and weight gain, percent weight gain and specific growth rate. The values of Feed Efficiency (FE) and Food Conversion Ratio (FCR) were best at the lower feeding levels. Although maximum weight gain is 8% feeding level, yet based upon cost benefit analysis, feeding at 4% rate was considered best. The economic profitability for the culture of African catfish in earthen ponds showed that net profit is increased on increasing feeding level from 2 to 4% of wet fish body weight, however, upon further increase in feeding level from 6 and 8%, the feed cost was increased that decreased the net profit. So, it was concluded that the feeding level of 4% wet fish body weight was optimum for economical production of African catfish in earthen pond culture system of Pakistan. [ABSTRACT FROM AUTHOR]

We investigated the effects of different temperature anomalies (up to +12 °C) on the biochemical features of sediments offered to specimens of the sea cucumber Holothuria (Holothuria) tubulosa (Gmelin, 1788) and of its feces. We also estimated ingestion and assimilation rates of different classes of organic compounds after the different treatments. The exposure to temperature anomalies influenced the metabolism and organic matter assimilation efficiency of H. tubulosa. Counterintuitively, our results would suggest that H. tubulosa , irrespectively of temperature, might not be the best option for removing excess organic matter from eutrophicated sediments, though having consequences on the organic matter nutritional quality. Since oceans' temperature is projected to further increase by 2100 along with frequency, intensity and duration of marine heatwaves, H. tubulosa will most likely experience a potential contraction of its distribution areal, with cascading consequences on benthic trophic webs dynamics. • Detritivore sea cucumbers are strong benthic bioturbators • Temperature influences sea cucumbers feeding behavior and feces composition • Heat waves affect sea cucumbers metabolism and, thus, benthic trophic status • Temperature exceeding 30 °C represent the highest limit of their thermal tolerance • Future changes in sea cucumbers distribution might alter sedimentary biogeochemistry [ABSTRACT FROM AUTHOR]

ABSTRAK Limbah cair tahu dari industri tahu di Kabupaten Bandung Barat memiliki kandungan senyawa organik yang tinggi. Salah satu sistem pengolahan air limbah yang dapat dilakukan secara efektif adalah Sequencing Batch Reactor (SBR). Tujuan dari penelitian ini adalah untuk mengetahui peforma terbaik SBR dalam meningkatkan efisiensi pengolahan limbah cair tahu. Pada penelitian ini dilakukan pembibitan (seeding), aklimatisasi, dan sistem SBR dengan tahapan variasi kecepatan pengumpanan. Kecepatan pengumpanan SBR pada saat pembibitan (seeding), aklimatisasi, dan running 1 sebesar 200 ml/hari dan sebesar 400 ml/hari pada saat running 2. Hasil penelitian ini memperoleh penurunan konsentrasi COD terbaik dari 8.000 mg/L menjadi 96 mg/L diperoleh pada running 1 dan penurunan konsentrasi COD dari 8.000 mg/L menjadi 160 mg/L diperoleh pada running 2. Efisiensi tertinggi yang dihasilkan adalah 98,8% pada running 1 dan 98% pada running 2. Kata kunci : Limbah cair tahu, Sequencing Batch Reactor (SBR), Kecepatan Pengumpanan ABSTRACT Tofu wastewater collected from the tofu industries in West Bandung Regency has a high organic content. One of the wastewater treatment systems that can be applied effectively is the Sequencing Batch Reactor (SBR) system. The purpose of this study was to find out the best performance of SBR in improving the efficiency of tofu wastewater treatment. This study conducted seeding, acclimatization, and SBR system that varied the feeding rates to find optimum value. The SBR feeding rate at the times of seeding, acclimatization, and running 1 amounted to 200 ml/day and amounted to 400 ml/day at the time of running 2. The results of this study were the best reduction in COD concentration from 8,000 mg/L to 96 mg/L obtained in the first running and reduction in COD concentration from 8,000 mg/L to 160 mg/L obtained in 2nd running. The highest efficiency produced was 98.8% on the first running 1 and 98% obtained from the 2nd running. Keywords: Tofu Wastewater, Sequencing Batch Reactor (SBR), Feeding Rates

The current study examined the combined effects of feeding rates and feeding types on the water quality, growth performance, digestive enzymes, blood parameters, and liver antioxidant enzymes of Nile tilapia (Oreochromis niloticus) fingerlings reared under a biofloc system. A 3 × 2 factorial experimental design was used with three feeding rates (2%, 3%, and 4%) and two feeding types (sinking or floating feed), comprising six treatments with three replicates. Fingerlings with an initial body weight of 4.50 ± 0.25 g were stocked in eighteen circular plastic tanks (0.5 m3) at a stocking density of 35 fish per tank fed three times a day at 10:00, 12:00 and 15:00. Starch was added to all treatments as an organic carbon source at a C/N ratio of 10:1. The phytoplankton community was determined to consist of twenty-two species, including individuals from the classes Cyanobacteria, Chlorophyceae, and Bacillariophyta. The most common phytoplankton classes were Chlorophyceae, followed by Cyanobacteria, and fish-fed floating feed at a feeding rate of 2% of total biomass yielded the greatest number of phytoplankton communities. Eight zooplankton species belonging to rotifers and protozoa were identified during this experiment. The highest values of final body weight, weight gain, and specific growth rate were recorded for a fish-fed floating diet with the highest feeding rate (4% of biomass). The highest hepatosomatic index (HIS) was detected in a fish-fed floating diet at a rate of 4% of total biomass. Though fish-fed sinking feed with a 4% biomass feeding rate presented the highest spleen index (SI). The highest significant (P 0.05) on hemoglobin (Hb), hematocrit (Hct), and red blood cells (RBCs). Feeding rate, feed type, and their interactions had no significant impact (P > 0.05) on serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), or albumin, but feeding rates or feed types had an effect (P

While solar ultraviolet radiation (UVR) is known to impact zooplankton, little has been documented on its impacts under elevated pCO 2. Here, we show that exposure to UVR decreased the feeding and survival rates of the copepod Acartia spinicauda , that artificial UV-B of 2.25 W·m−2 for 4 h resulted in a 52 % inhibition of its grazing rates and a 45 % reduction in survival rates compared to visible light alone. On the other hand, an increase in pCO 2 to 1000 μatm (pH drop of 0.4) immediately and significantly increased the UVR-induced inhibition of feeding. Subsequently, the combination of the high pCO 2 (1000 μatm) and UVR resulted in about 65 % lethal impact, with UV-A contributing 21 % and UV-B 44 % compared to the visible light alone and ambient pCO 2 conditions. While the copepod was shown to be able to sense and escape from UV-exposed areas, these findings suggest that UVR impacts on the copepod can be exacerbated with progressive ocean acidification or in high CO 2 waters, including upwelled regions. • Impact of UVR on the Physiological Activities of Copepod : • Exposure to UV-B radiation (2.25 W·m-2 for 4 hours) significantly inhibits the grazing rates (by 52 %) and reduces the survival rates (by 45 %) of the copepod Acartia spinicauda compared to visible light alone. • Synergistic Detrimental Effects of UVR and Elevated pCO 2 : • The combination of high pCO 2 and UVR results in approximately 65 % lethal impact on A. spinicauda , with UV-A contributing 21 % and UV-B contributing 44 % to the mortality compared to visible light alone and ambient pCO 2 conditions. • Photoprotective and Avoidance Behaviors : • A. spinicauda exhibits avoidance behavior by migrating to regions not exposed to UV radiation. [ABSTRACT FROM AUTHOR]

Crown-of-thorns seastars (COTS, Acanthaster spp.) are a major contributor to coral mortality across the Indo-Pacific and can cause extensive reef degradation. The diet preferences of COTS can influence coral community structure by predation on fast-growing genera such as Acropora and avoidance of rare coral genera. In non-outbreaking populations, this preference can increase species diversity. The feeding biology of Acanthaster cf. solaris was compared at two sites (Shark Alley and Second Lagoon) on One Tree Island reef, located in the southern Great Barrier Reef, to determine whether the availability of Acropora influences differences in COTS movement, feeding preference and feeding rates within the same reef system. Acanthaster cf. solaris were tracked daily for five days across both sites, with measurements of movement, feeding scars and coral composition recorded over this time. While Shark Alley and Second Lagoon have similar live coral cover (40 and 44 % respectively), Shark Alley has significantly lower Acropora availability than Second Lagoon (2 vs 32 %). The feeding rate of COTS was significantly different between Shark Alley and Second Lagoon (259.8 and 733.8 cm2 of coral per day, respectively), but did not differ between seastar size (25–40 cm and >40 cm). Acanthaster cf. solaris showed preference for Pocillopora , Seriatopora , Acropora and Isopora and an avoidance of Porites at both sites. The results suggest that for coral reef sites where Acropora is not dominant, COTS outbreaks may be less likely to initiate, with comparatively low feeding rates found in comparison to coral reefs where Acropora is dominant. • Feeding behaviour of crown-of-thorns seastars (COTS) were compared across two sites. • Feeding rates were higher in sites with high Acropora availability. • Movement rates and feeding preferences did not differ between sites. • Feeding preferences are similar between stable and outbreaking populations. • Reefs where Acropora is rare are less able to support COTS outbreaks. [ABSTRACT FROM AUTHOR]

Predator functional responses describe predator feeding rates and are central to predator–prey theory. Originally defined as the relationship between predator feeding rates and prey densities, it is now well known that functional responses are shaped by a multitude of factors. However, much of our knowledge about how these factors influence functional responses is based on laboratory studies that are generally logistically constrained to examining only a few factors simultaneously and that have unclear links to the conditions organisms experience in the field.We apply an observational approach for measuring functional responses to understand how sex/stage differences, temperature and predator densities interact to influence the functional response of zebra jumping spiders on midges under natural conditions.We used field surveys of jumping spiders to infer their feeding rates and examine the relationships between feeding rates, sex/stage, midge density, predator density and temperature using generalized additive models. We then used the relationships supported by the models to fit parametric functional responses to the data.We find that feeding rates of zebra jumping spiders follow some expectations from previous laboratory studies such as increasing feeding rates with body size and decreasing feeding rates with predator densities. However, in contrast to previous results, our results also show a lack of temperature response in spider feeding rates and differential decreases in the feeding rates of females and juveniles with densities of different spider sexes/stages.Our results illustrate the multidimensional nature of functional responses in natural settings and reveal how factors influencing functional responses can interact with one another through behaviour and morphology. Further studies investigating the influence of multiple mechanisms on predator functional responses under field conditions will increase our understanding of the drivers of predator–prey interaction strengths and their consequences for communities and ecosystems. [ABSTRACT FROM AUTHOR]

Fishes are subject to numerous stressors, including climate change, fishing and impacts by alien species. One of the challenges in understanding species and community responses to these stressors is identifying how they modify predator–prey interactions, a key process shaping aquatic food webs. Here, we aim to synthesize how species traits, such as size, activity level and alien status, and environmental factors, such as water temperature, shape the functional response: the change in predator consumption rate in relation to changes in prey density. We compiled over 300 fish functional responses and examined sources of variation in two key parameters dictating its shape: handling times and space clearance rates. We found that compared to cold waters, warmer waters were characterized by decreased handling times and increased space clearance rates for smaller predators, but had an opposite effect for bigger predators, suggesting that, across species, altered predation rates may underlie the decrease in size at higher temperatures (the temperature‐size rule). We also found that the negative effect of increased temperature on the functional response of larger predators is more pronounced in active species. Finally, we found that known alien species do not exhibit different functional response parameters when examined on their native prey, suggesting that alien species are not primed for invasion via their high functional response. Together, these asymmetric changes imply that, across species, warmer waters may alter predator–prey relationships differentially according to predator size, prey size and activity levels. [ABSTRACT FROM AUTHOR]

Nest provisioning and diet of nestling yellow-rumped tinkerbird Pogoniulus bilineatus We found feeding rates were higher in the morning compared to the afternoon, consistent with previous work (Dor et al., 2006; Garcia-Navas & Sanz, 2011), which suggested begging rates drove higher feeding rates in the morning. Feeding rate and diet We assessed feeding rate and diet of I Pogoniulus bilineatus i by videotaping nest visitation of both parents, recording daily from 05:00 to 18:00 for eight days. Keywords: barbet; camera trap; feeding rates; parental care EN barbet camera trap feeding rates parental care 75 78 4 02/28/22 20220301 NES 220301 INTRODUCTION The frequency with which birds deliver food to their young varies based on nestling begging rates, time of day and parental contribution (Balshine, 2012; Moreno et al., 1995; Rossmanith et al., 2007). [Extracted from the article]

Abstract Temperature dependency of consumer–resource interactions is fundamentally important for understanding and predicting the responses of food webs to climate change. Previous studies have shown temperature‐driven shifts in herbivore consumption rates and resource preference, but these effects remain poorly understood for predatory arthropods. Here, we investigate how predator killing rates, prey mass consumption, and macronutrient intake respond to increased temperatures using a laboratory and a field reciprocal transplant experiment. Ectothermic predators, wolf spiders (Pardosa sp.), in the lab experiment, were exposed to increased temperatures and different prey macronutrient content (high lipid/low protein and low lipid/high protein) to assess changes in their killing rates and nutritional demands. Additionally, we investigate prey mass and lipid consumption by spiders under contrasting temperatures, along an elevation gradient. We used a field reciprocal transplant experiment between low (420 masl; 26°C) and high (2,100 masl; 15°C) elevations in the Ecuadorian Andes, using wild populations of two common orb‐weaver spider species (Leucauge sp. and Cyclosa sp.) present along the elevation gradient. We found that killing rates of wolf spiders increased with warmer temperatures but were not significantly affected by prey macronutrient content, although spiders consumed significantly more lipids from lipid‐rich prey. The field reciprocal transplant experiment showed no consistent predator responses to changes in temperature along the elevational gradient. Transplanting Cyclosa sp. spiders to low‐ or high‐elevation sites did not affect their prey mass or lipid consumption rate, whereas Leucauge sp. individuals increased prey mass consumption when transplanted from the high to the low warm elevation. Our findings show that increases in temperature intensify predator killing rates, prey consumption, and lipid intake, but the responses to temperature vary between species, which may be a result of species‐specific differences in their hunting behavior and sensitivity to temperature.

Abstract Food ingestion is one of the most basic features of all organisms. However, obtaining precise—and high‐throughput—estimates of feeding rates remains challenging, particularly for small, aquatic herbivores such as zooplankton, snails, and tadpoles. These animals typically consume low volumes of food that are time‐consuming to accurately measure. We extend a standard high‐throughput fluorometry technique, which uses a microplate reader and 96‐well plates, as a practical tool for studies in ecology, evolution, and disease biology. We outline technical and methodological details to optimize quantification of individual feeding rates, improve accuracy, and minimize sampling error. This high‐throughput assay offers several advantages over previous methods, including i) substantially reduced time allotments per sample to facilitate larger, more efficient experiments; ii) technical replicates; and iii) conversion of in vivo measurements to units (mL‐1 hr‐1 ind‐1) which enables broad‐scale comparisons across an array of taxa and studies. To evaluate the accuracy and feasibility of our approach, we use the zooplankton, Daphnia dentifera, as a case study. Our results indicate that this procedure accurately quantifies feeding rates and highlights differences among seven genotypes. The method detailed here has broad applicability to a diverse array of aquatic taxa, their resources, environmental contaminants (e.g., plastics), and infectious agents. We discuss simple extensions to quantify epidemiologically relevant traits, such as pathogen exposure and transmission rates, for infectious agents with oral or trophic transmission.

Theory suggests that intraspecific trait variation will alter species interaction strengths through nonlinear averaging when interaction strengths are nonlinear functions of individuals' traits. This effect is expected to be widespread, yet what factors mediate its magnitude in nature and hence its potential effects on ecosystems and communities are unclear.We sought to quantify how nonlinear predator functional responses, variation in prey densities and counteracting variation in attack rates and handling times among predator individuals of similar body size alter their population‐level feeding rates through nonlinear averaging in a natural system, and to determine the processes influencing the net magnitude of this effect.We used a field caging experiment in the rocky intertidal of Oregon, USA to quantify attack‐rate variation and feeding rates of the whelk Nucella ostrina on its barnacle and mussel prey. We also used empirically parameterized simulations to examine the effects of handling‐time variation among individuals on population‐level feeding rates.Within cages, individual attack‐rate variation reduced population‐level whelk feeding rates. However, the magnitude of this reduction differed among prey species and cages depending on cage‐specific magnitudes of attack‐rate variation and functional‐response nonlinearity. The inferred effects of handling‐time variation among individuals were of smaller magnitude than those of attack‐rate variation, yet counteracted them to cause a net weakening of the effect of individual attack‐rate variation on population‐level feeding rates. Across cages, attack‐rate and prey‐density variation had non‐additive effects that produced greater feeding‐rate reductions at the experiment scale relative to the cage scale.Our results indicate that the effects of trait variation via nonlinear averaging depend critically on the features of systems that determine the magnitudes of nonlinearities and trait variation. Because of counteracting trait variation, nonlinear‐averaging effects may be quite complex, involving both the variances and covariances of all traits and environmental variables influencing the ecological process of interest. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Predator functional responses describe predator feeding rates and are central to predator–prey theory. Ecologists have measured thousands of predator functional responses using the same basic experimental method. However, this design is ill‐suited to address many current questions regarding functional responses. We derive a new experimental design and statistical analysis that quantifies functional responses using the times between a predators' feeding events requiring only one or a few trials. We examine the feasibility of the experimental method and analysis using simulations to assess the ability of the statistical model to estimate functional response parameters and perform a proof‐of‐concept experiment estimating the functional responses of two individual jumping spiders. Our simulations show that the statistical method reliably estimates functional response parameters. Our proof‐of‐concept experiment illustrates that the method provides reasonable estimates of functional response parameters. By virtue of the fewer number of trials required to measure a functional response, the method derived here promises to expand the questions that can be addressed using functional response experiments and the systems in which they can be measured. Thus, we hope that our method will refine our understanding of functional responses and predator–prey interactions more generally. [ABSTRACT FROM AUTHOR]

One of the essential factors to be addressed in the development of aquaculture is the feeding regime. This study was investigated to assess the effects of feeding rate on growth performance, feed utilization, chemical body composition survival rate, cannibalism and morphological indices of Asian Seabass, Lates calcarifer. Intended for the trial, one hundred forty sea bass individuals with an average weight 5.47 ± 0.11 g were randomly distributed in 4 concrete tanks (914 cm × 183 cm 122 cm) each; length × width × depth) and volume 18,399 L, for total 68 days. The fishes were fed with a pelleted diet containing 46% crude protein for different feeding groups designated as (T1, T2, T3 and T4). The feed was supplied with a rate of (T1) 3%, (T2) 4%, (T3) 6%, and (T4) 9% of fish biomass per day and feeding frequency were maintained three times per day to all the groups. At the end of the trial water physicochemical parameters was in acceptable range for Asian sea bass growth. The average daily weight gain (g), weight gain (g) and specific growth rate (%) was significantly higher (p < 0.05) in T3 and T4 as compared to T1 and T2 group. The poorest feed conversion ratio was recorded in T1 group with 3% biomass per day. The cannibalism rate was significantly (p < 0.05) higher in T1 (3%) compared to T3 and T4 treatment. The morphological indices, condition factors (CF), viscerosomatic index and hepatosomatic index (HSI) was significantly higher in T4 group as compared to other treatments. The protein, moisture and ash contents of the whole biomass of the Asian sea bass were not significantly influenced by feeding rate. The fat levels in the fish bodies increased significantly (p < 0.05) with increasing feeding ratio. The phenomenal regression indicates that 6.5% feeding rate per day is optimum for best growth performance, survival and minimum cannibalism rate for Asian sea bass in captivity. The outcome of the finding will help in promotion for not only the coastal aquaculture in Pakistan abut also elsewhere. [ABSTRACT FROM AUTHOR]

Temperature dependency of consumer–resource interactions is fundamentally important for understanding and predicting the responses of food webs to climate change. Previous studies have shown temperature‐driven shifts in herbivore consumption rates and resource preference, but these effects remain poorly understood for predatory arthropods. Here, we investigate how predator killing rates, prey mass consumption, and macronutrient intake respond to increased temperatures using a laboratory and a field reciprocal transplant experiment. Ectothermic predators, wolf spiders (Pardosa sp.), in the lab experiment, were exposed to increased temperatures and different prey macronutrient content (high lipid/low protein and low lipid/high protein) to assess changes in their killing rates and nutritional demands. Additionally, we investigate prey mass and lipid consumption by spiders under contrasting temperatures, along an elevation gradient. We used a field reciprocal transplant experiment between low (420 masl; 26°C) and high (2,100 masl; 15°C) elevations in the Ecuadorian Andes, using wild populations of two common orb‐weaver spider species (Leucauge sp. and Cyclosa sp.) present along the elevation gradient. We found that killing rates of wolf spiders increased with warmer temperatures but were not significantly affected by prey macronutrient content, although spiders consumed significantly more lipids from lipid‐rich prey. The field reciprocal transplant experiment showed no consistent predator responses to changes in temperature along the elevational gradient. Transplanting Cyclosa sp. spiders to low‐ or high‐elevation sites did not affect their prey mass or lipid consumption rate, whereas Leucauge sp. individuals increased prey mass consumption when transplanted from the high to the low warm elevation. Our findings show that increases in temperature intensify predator killing rates, prey consumption, and lipid intake, but the responses to temperature vary between species, which may be a result of species‐specific differences in their hunting behavior and sensitivity to temperature. [ABSTRACT FROM AUTHOR]

Food ingestion is one of the most basic features of all organisms. However, obtaining precise—and high‐throughput—estimates of feeding rates remains challenging, particularly for small, aquatic herbivores such as zooplankton, snails, and tadpoles. These animals typically consume low volumes of food that are time‐consuming to accurately measure.We extend a standard high‐throughput fluorometry technique, which uses a microplate reader and 96‐well plates, as a practical tool for studies in ecology, evolution, and disease biology. We outline technical and methodological details to optimize quantification of individual feeding rates, improve accuracy, and minimize sampling error.This high‐throughput assay offers several advantages over previous methods, including i) substantially reduced time allotments per sample to facilitate larger, more efficient experiments; ii) technical replicates; and iii) conversion of in vivo measurements to units (mL‐1 hr‐1 ind‐1) which enables broad‐scale comparisons across an array of taxa and studies.To evaluate the accuracy and feasibility of our approach, we use the zooplankton, Daphnia dentifera, as a case study. Our results indicate that this procedure accurately quantifies feeding rates and highlights differences among seven genotypes.The method detailed here has broad applicability to a diverse array of aquatic taxa, their resources, environmental contaminants (e.g., plastics), and infectious agents. We discuss simple extensions to quantify epidemiologically relevant traits, such as pathogen exposure and transmission rates, for infectious agents with oral or trophic transmission. [ABSTRACT FROM AUTHOR]

Comparative studies have established the necessity for biparental care as an important factor for monogamy in freshwater fish and birds. However, whether two parents are really needed for offspring care remains an open question in many cases. I experimentally studied female and male contributions to offspring care in the white‐browed coucal (Centropus superciliosus), a monogamous and biparental cuckoo with a balanced adult sex ratio, and contrasted it with the sympatric black coucal (C. grillii), a classically polyandrous species with a male‐biased adult sex ratio and male‐only care. To study the necessity for biparental care, I temporarily removed one partner for 2 days to see whether the remaining parent compensated for the absence of its partner. Both female and male white‐browed coucals approximately doubled their feeding rates when their partner was absent, thus fully compensating the number of feeding visits to the nest. However, nestlings maintained their growth only, when males were present and females were removed. When males were removed and only females were present, nestling growth declined. Hence, only male white‐browed coucals fully compensated for the temporary loss of the partner, suggesting that females could benefit most from nesting with additional males—if these should become available. Removing female black coucals had no consequence for nestling feeding rates of male black coucals. But male black coucals had to be returned to their territories within a few hours to avoid harming the brood because female black coucals typically would not commence feeding their offspring. In conclusion, the breeding system of white‐browed coucals seems quite flexible and the relatively balanced adult sex ratio may stabilize monogamy in this species. Should ecological factors ever favour a stronger bias in the adult sex ratio towards males, female white‐browed coucals may easily become polyandrous and relinquish parental care entirely to males. [ABSTRACT FROM AUTHOR]

The evolution of foraging in Drosophila melanogaster (Meigen) is studied using outbred populations that had been differentiated using laboratory selection. The foraging behaviour of Drosophila larvae is measured using the foraging path length of 72-h-old larvae. The foraging path length is the distance travelled by foraging larvae over 5 min. Populations of Drosophila selected for rapid development show significantly greater path lengths than their controls. Populations of Drosophila selected for resistance to ammonia and urea in their larval food have shorter path lengths than their controls. Individuals in the ammonia-resistant populations are smaller than those in the control populations, but the size-adjusted metabolic rates are not significantly different. A simple model is proposed suggesting that changes in larval foraging behaviour may be a means for Drosophila larvae to adapt to new environments that require additional maintenance energy. In the ammonia-selected populations, crucial tests of these ideas will have to be conducted in environments with ammonia.

Daily energy intake of adult female mammals is influenced by environmental conditions and physiological requirements, including reproduction. We examined the effects of fruit availability on macronutrient and metabolisable energy (ME) intake by adult female chimpanzees (Pan troglodytes schweinfurthii) of the Kanyawara community in Kibale National Park, Uganda, from January 2014 through June 2015. Drupe fruits were abundant for 4 months, whereas the other 14 months were dominated by fig fruits. The mean daily intake of food (dry matter) and ME did not differ between drupe‐months and fig‐months. However, foraging costs were higher during fig‐months, as indicated by a 20% increase in feeding time. Furthermore, during drupe‐months female chimpanzees ingested more water‐soluble carbohydrates and lipids, and less available protein and neutral detergent fibre. Although ME intake did not differ consistently between drupe‐months and fig‐months, they consumed more on days when ripe fruit dominated the diet than when leaves and pithy stems dominated the diet. Our data suggest that differences in diet quality between drupes and figs can have important effects on frugivore foraging and that they influence net energy gain more by their effects on macronutrient composition or foraging cost than by their direct impact on energy intake. [ABSTRACT FROM AUTHOR]

The rate that consumers encounter resources in space necessarily limits the strength of feeding interactions that shape ecosystems. To explore the link between encounters and feeding, we first compiled the largest available dataset of interactions in the marine benthos by extracting data from published studies and generating new data. These data indicate that the size‐scaling of feeding interactions varies among consumer groups using different strategies (passive or active) to encounter different resource types (mobile or static), with filter feeders exhibiting the weakest feeding interactions. Next, we used these data to develop an agent‐based model of resource biomass encounter rates, underpinned by consumer encounter strategy and resource biomass density. Our model demonstrates that passive strategies for encountering small, dispersed resources limits biomass encounter rates, necessarily limiting the strength of feeding interactions. Our model is based on generalisable assumptions, providing a framework to assess encounter‐based drivers of consumption and coexistence across systems. [ABSTRACT FROM AUTHOR]

Rotifers play an important role in biogeochemical cycles and organic productivity of freshwater ecosystems due to their high metabolic rates. Information on filter feeding, their main process of energy acquisition, are relevant and still scarce for tropical regions. The rotifers of the class Bdelloidea feed by filtration or scraping consuming small food items, such as bacteria, algae, yeasts or particulate organic matter. We know little of their role in the trophic dynamics in the habitats they occupy and so the aim of this study was to quantify laboratory filtration and ingestion rates of the rotifer Philodina roseola, fed with Raphidocelis subcapitata. The experiment consisted of 10 adult exposure treatment at five concentrations approximately in the range between 104 and 107 cells mL-1, at the temperature of 25 ± 1 °C. The experiments lasted one hour and initial and final concentrations of the algal suspensions were determined by counting the number of cells in a Neubauer chamber. There were no significant differences between the initial and final concentrations of cells in the control group indicating that algal growth did not occur. Philodina roseola filtration rates varied between 0.09 and 0.25 mL ind-1 h-1. Given that filtration is the main process of energy acquisition by Philodina roseola, as well as for most other rotifers, and that it comprises important issues related to trophic dynamics of aquatic ecosystems, additional experimental information is especially important and need to be extended to other types of food and combinations of experimental conditions.

The trophic ecology of the sea urchin Paracentrotus lividus, a key species in several shallow benthic communities, has been intensively studied, but the role of various foods in the processes of growth and gonadal maturation is still scarcely understood. This research assessed the effects of two fundamental food items for wild specimens of the sea urchin Paracentrotus lividus, the tissues of the seagrass Posidonia oceanica and of the green alga Ulva rigida, compared to the effect of a commercial compound feed on the somatic growth, gonad development, fertilization success and post-embryonic development. Consumption rates along with the C/N ratios were measured in the feeds and in the faecal pellets. We demonstrated that feeding for three months on U. rigida and P. oceanica did not affect growth and gonadal index of adults, fertilization processes and first cleavage and development, as well as field-collected animals. In contrast, a diet based on formulated pellets triggered a significant increase of gonadal index, but lack of gamete production, due to a follicular hyperthrophy. Our work will be useful for the definition of optimal diets for the production of mature broodstocks of an ecologically important marine model organism. Impact statement- We aim at defining the daily feeding rate of the sea urchin P. lividus - P. lividus represents a key species in various benthic communities. - Feeds are important in the processes of growth and gonadal maturation of sea urchins. - Several factors influence sea urchin feeding rates. [ABSTRACT FROM AUTHOR]

Abstract The recent decrease in seawater pH has stimulated a great deal of research on the effects of ocean acidification on various organisms. Most of these studies have mainly focused on the direct effects of acidification on organisms. However, the effects on ecological interactions have been poorly studied. In this paper we have focused on determining the effects of acidification on feeding rates of two species of sea urchins, Paracentrotus lividus and Diadema africanum through laboratory experiments. Nine algae species were reared under two pH treatmens (ph = 8.1 vs. pH = 7.6) for 10 days. We evaluated possible changes in calcification rates, growth and internal structure. Then these algae were offered to juvenile sea urchins for 7 days, evaluating the consumption rates of juvenile sea urchins under these different pH conditions. The algae reared in the control treatment showed higher growth rates and concentration of calcium carbonate, however no internal structural changes were observed in any algae. Juvenile Paracentrotus lividus showed higher consumption rates on algae previously subjected to pH 7.6 than on algae reared under control conditions and between algae species in low pH.The algae most consumed were C. liebetruthii, C. abies-marina and C. elongata by P. lividus juveniles from low pH treatment. However in D. africanum the feeding rates were similar between treatments. This study demonstrated the negative effects of low pH on various species of algae in growth, and indirectly the increase in herbivory rates of juvenile sea urchins on algae reared under low pH. Highlights • Ocean acidification increase the feeding rates of juveniles of P. lividus on algae reared at low pH. • Were not significant differences in feeding rates of D. africanum between algae reared under low pH and control pH. • This investigation highlights indirect effects of ocean acidification such as increase in herbivores pressure. • Ocean acidification affects growth of 9 algae species from Canary Islands. • A future scenario of climate change could affect the palatability of algae and their growth. [ABSTRACT FROM AUTHOR]

This study investigated feeding management of yellowfin seabream, Acanthopagrus arabicas, juveniles under different feeding rates and its relationship to growth performance, survival, cannibalism and body composition. Thirty healthy fish (21.87±0.22g initial weight) were stocked in 12 separate net cages 3.4m3 assigned to four groups: F1, F2, F3, and F4 to receive feed at 3%, 5%, 7% and 9% body weight per day (bw/d). The juveniles were fed twice daily with a diet containing 42% protein for seven weeks. At the end of the feeding trial, group F3, fed at 7% bw/d, had significantly (P<0.05) higher percent weight gain, average daily weight gain and specific growth rate, followed by groups F2 (5% bw/d) and F4 (9% bw/d). The poorest growth performance was recorded in F1 (3% bw/d). Cannibalism was not seen in any treatment group, and survival was recorded 100%. In the whole fish body proximate composition, protein, ash and moisture showed no change while lipid levels in the fish bodies increased with increasing feeding ratio. Based on the results, 7% bw/d was the optimum feeding rate for J. arabicas under given experimental conditions. [ABSTRACT FROM AUTHOR]

Coastal Antarctic waters involve habitats of high primary and secondary production with a remarkable sensitivity to environmental changes on different spatio-temporal scales. The current study is the first comprehensive approach to the spatial distribution and the fluctuations in abundance, biomass, community structure, and diversity of the mesozooplankton from different habitats located in Scotia Bay in summers: 2014 and 2015, characterized by a different timing in seasonal sea ice retreat. Mean seawater temperature and abundances of calanoids, cyclopoids, nauplii, and appendicularians were one order of magnitude higher in summer 2014. Despite these environmental differences, biomass values of these groups proved similar for both summers. A total of ten species of copepods and one of appendicularians (Fritillaria borealis) were identified. Oithonid copepods—O. similis, followed by O. frigida—represented the bulk of mesozooplankton abundances in both summers. The highest total mesozooplankton abundance (2111 ind m−3) and biomass (14075 µg C m−3) were found next to an Adélie penguin breeding area (2014), while the highest Shannon index values were found next to a glacier in both summers. Multivariate analyses based on species abundance showed two main groups of sites, one of them encompassing all summer 2014 samplings and the other comprising all summer 2015 samplings. The positive correlation between O. similis and the 2-10 μm Chl-a fraction suggests that summer 2014 represented optimal conditions—in terms of food—for the growth and development of this species. Experimental studies based on natural prey assemblages revealed that O. similis feeds on flagellates rather than on diatoms. [ABSTRACT FROM AUTHOR]

• Contamination of SePM has negative effects at high concentrations on Daphnia magna. • SePM caused an effect on the spatial distribution of organisms from 5 g/L at 24 h. • We found an increase in the number of neonates and an advance of the first brood. • A neurotoxic effect was observed due to the presence of high concentrations of SePM. • Feeding rate was significantly lower after a long pre-exposure (23 days). Metallurgical industries are a continuous source of air pollution due to the amount of settleable particulate matter (SePM) they release. This SePM is a complex mixture formed by metallic nanoparticles and metals, which reach terrestrial and aquatic ecosystems and can be a significant source of contamination. The aim of this study was to evaluate the adverse effects of SePM at different levels of biological organization in order to estimate its ecological impacts on aquatic ecosystems. For this purpose, the crustacean Daphnia magna was exposed to different concentrations of SePM (0.01, 0.1, 1, 5, 10 g/L) using a multi-level response approach. The endpoints studied were: avoidance throughout 24 h in a non-forced exposure system, reproduction (total number of neonates per female after 21 days of exposure), acetylcholinesterase activity (AChE) after 48 h, and finally, the feeding rates during a short-term exposure (48 h) and a long-term exposure (21 day + 48 h). There was a negative effect of SePM on all responses measured at high concentrations. The avoidance was concentration-dependent and represented 88 % and 100 % at the two highest concentrations. The AChE activity was significantly inhibited at 5 and 10 g/L. The total number of neonates increased from 1 g/L of SePM and the first brood occurred earlier as of 5 g/L compared to control. The post-exposure feeding rates were lower during long-term exposure at the highest concentration. Chemical analyses were performed to characterize the metals present in this SePM, but this study did not report any direct relationship with toxicity, due to the chemical heterogeneity of the particles. The emission of compounds caused by anthropogenic activity may have significant ecological consequences, so it is important to consider these possible effects on aquatic biota generated by the mixture of metals present in SePM originated from metallurgical activities. Environmental and sectorial regulations are needed to prevent contamination and ecological disturbances. [ABSTRACT FROM AUTHOR]

An 8-week feeding trial was conducted to investigate the effects of feeding rates on growth, feed utilization, and body composition of juvenile Pseudobagrus ussuriensis. Juvenile P. ussuriensis (initial body weight of 2.30 ± 0.01 g) were distributed into 15 tanks, and each tank was stocked with 30 fish. Satiation feeding (3.57% BW day) was determined by the point of cessation of voluntary feeding activity by fish. Five treatments that included triplicate groups were prepared for this study: 100% (satiation), 75, 50, and 25% of satiation groups and unfed group. The results indicated that weight gain (WG) and specific growth rate (SGR) increased with increasing feeding rates. WG and SGR of fish fed to satiation were significantly higher than that of fish fed to 50 and 25% of satiation and unfed fish ( P < 0.05), but not significantly different from that of fish fed to 75% of satiation ( P > 0.05). Feed efficiency (FE) and protein efficiency ratio (PER) of fish fed to 75% of satiation were significantly higher than that of fish fed other groups. There was a trend towards increased whole-body crude lipid and decreased whole-body moisture with increasing feeding rates, while whole-body protein content was not significantly affected by feeding rates. Condition factor and hepatosomatic index were increased with increasing feeding rates ( P < 0.05), while there was no significant difference in viscerosomatic index with increasing feeding rates. Considering these experimental results, it can be concluded that the optimum feeding rate for growth of juvenile P. ussuriensis could be lowered to 75% of satiation without growth suppression. [ABSTRACT FROM AUTHOR]

The Wedge-billed Woodcreeper ( Glyphorynchus spirurus) is a common suboscine passerine of lowland forests of the Neotropics. While nest sites and incubation behavior for the species have been described, information about courtship and fledgling care are absent. As part of a separate study on the movement patterns of Wedge-billed Woodcreepers in eastern Ecuador, we observed a previously undescribed display behavior and collected data on fledgling feeding rates. We observed a neck-extension behavior performed synchronously by two interacting individuals that appears to play a role in courtship, but is also performed in aggressive contexts. Given that only 5 of 23 tracked adults were known to be breeding during the study period (Jan-Apr 2012), it is likely that the breeding season in this area extends well before and after this time period. Molt and breeding activities coincided for two individuals. Fledgling feeding rates ranged from 0.47-2.0 feeds/hr for adults from three nests; observation of only one fledgling (whereas two nestlings are typical) with each tracked adult might indicate brood splitting soon after fledging. [ABSTRACT FROM AUTHOR]

Two methods are commonly used to describe the feeding behavior of wild primates, one based on the proportion of time animals spent feeding on specific plant parts ('time-based' estimates) and one based on estimates of the actual amounts of different plant materials ingested (''weight-based' estimates). However, studies based on feeding time may not be accurate for making quantitative assessments of animals' nutrient and energy intake. We analyzed the diet of two groups of Alouatta pigra living in forest fragments using two different methods (time- and dry weight-based estimates), to explore how these alternative approaches impact estimates of (a) the contribution of each food type to the diet and (b) the macronutrient composition of the diet, including available protein (AP), non-protein energy (NPE), and total energy (TE) intake. We conducted behavioral observations ( N = 658 hr and N = 46 full day focal follows), from August 2012 to March 2013. For each feeding bout, we estimated both time spent feeding and actual fresh- and dry-weight consumption by counting the number of food items ingested during the bout. Using time-based estimates, A. pigra showed a predominantly leaf-based diet. In contrast, weight-based estimates described combined a fruit and leaf-based diet. There were no differences between methods when estimating AP intake; however, we found significant differences while estimating NPE and TE intake. Time-based estimates provide us with important information such as the foraging effort spent on food items, trees, or patches, while weight-based estimates may provide more accurate information concerning nutrient and energy intake. We suggest that quantitative estimates of nutrient intake in a primate's diet be based on observations of wet and/or dry weight actually ingested rather than extrapolated from time spent feeding. [ABSTRACT FROM AUTHOR]

Short-term experiments were carried out to study the feeding performances of the copepod Euterpina acutifrons fed on Thalassiosira weissiogii. Four adult females of this species were sorted and transferred to 15 ml glass bottles filled with different dilutions of the diatom cultures to obtain cell concentrations of 7.5, 10.0, 12.5, 15.0, 17.5, 20.0, 22.5 and 25.0 x 103 cell.ml-1 (8 treatments, 3 replicates, 4 copepods/replicate). Initial and final cell concentrations of control and experimental bottles were determined using a Neubauer Chamber. Filtration and ingestion rates were measured thought 1 hour grazing trials performed under controlled laboratory conditions. Filtration rates of Euterpina acutifrons oscillated from 0.81 to 2.92 ml. copepod-1 .h-1 and they significantly higher (p

Background: Orangutans have one of the slowest-paced life histories of all mammals. Whereas life-history theory suggests that the time to reach adulthood is constrained by the time needed to reach adult body size, the needing-to-learn hypothesis instead suggests that it is limited by the time needed to acquire adult-level skills. To test between these two hypotheses, we compared the development of foraging skills and growth trajectories of immature wild orangutans in two populations: at Tuanan (Pongo pygmaeus wurmbii), Borneo, and Suaq Balimbing (Pongo abelii), Sumatra. We collected behavioral data on diet repertoire, feeding rates and ranging competence during focal follows, and estimated growth through non-invasive laser photogrammetry. Results: We found that adult-like diet repertoires are attained around the age of weaning and that female immatures increase their repertoire size faster than their male peers. Adult-level feeding rates of easy techniques are reached just after weaning, but several years later for more difficult techniques, albeit always before adulthood (i.e. age at first reproduction). Independent immatures had faster feeding rates for easy to process items than their mothers, with male immatures achieving faster feeding rates earlier in development relative to females. Sumatran immatures reach adult-level feeding rates 2-3 years later than their Bornean peers, in line with their higher dietary complexity and later weaning. The range-use competence of independently ranging and weaned immatures is similar to that of adult females. Body size measurements showed, immatures grow until female age of first reproduction. Conclusions: In conclusion, unlike in humans, orangutan foraging skills are in place prior to reproduction. Growth trajectories suggest that energetic constraints, rather than skills, best explain the length of immaturity. However, skill competence for dietary independence is reached later where the adult niche is more complex, which is consistent with the relatively later weaning age with increasing brain size found generally in primates, and apes in particular. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the survivorship and growth performance of Panulirus longipeslongipes fed with Sardinella spp. in floating netcages at different feeding rates and to determine whichfeeding rate provides the best feed conversion ratio.Results showed that a feeding rate of 20% gave the highest growth (final average weight) followed by15% and 10% feeding rates, respectively. In terms of length increment, 20% feeding rate likewisepromoted the highest increment.Differences in feed conversion ratio among treatments was significant (P

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The objective of our study was to establish an optimal feeding frequency and feeding rate for rearing hybrid sturgeon ( Acipenser schrenckii Brandt♀ × A . baeri Brandt♂) in production during the juvenile growth phase. The growth and survival of juvenile hybrid sturgeon were determined at four different feeding rates and three different frequencies. The feeding rates were 2%, 3%, 4%, and 5% body weight per day, and these daily rations were offered in 2, 4, and 6 fractions over the day. Thus, a 4 × 3 experimental design was used with triplicates per treatment involving a total of 36 tanks. Initial stocking density was 400 fish per tank with initial body weight of 7.79 ± 0.37 g. Fish were kept at 18 ± 1.0 °C in circular tanks and fed one commercial diet (41% protein, 12% lipid, 9–10% moisture and 10% ash). Fish were weighed every 2 weeks to regulate the feeding rates, and the number of fish per tank was reduced by 50% every 4 weeks to maintain the same stocking density. After 12 weeks of feeding, all fish were sampled for weight measurements. Survival, weight gain ratio (WGR), specific growth rate (SGR), feed efficiency (FE), and feeding costs were calculated. Feeding frequency markedly affected WGR and SGR ( P < 0.01), but had no significant effect on FE and feed cost ( P > 0.05). All parameters were significantly affected by feeding rate ( P < 0.01). The interaction between feeding rates and feeding frequencies had significant effects on final body weight (FBW) and WGR ( P < 0.05). Fish fed 5% BW/day administered in 6 portions resulted in the highest WGR ( P < 0.01). Broken line analysis on SGR indicated the optimum feeding rates of juvenile hybrid sturgeon to be 3.7% BW/day. The body composition did not result in a significant difference in all treatments ( P > 0.05). Statement of relevance The research of AQUA-D-14-00653 determines more effective feeding frequency and rate for juvenile hybrid sturgeon under commercial production conditions. [ABSTRACT FROM AUTHOR]

Estuarine nearshore environments are important habitats for many organisms, including juveniles of several Pacific salmon species ( Oncorhynchus spp.). These habitats provide shallow water and high prey productivity, but are increasingly modified by anthropogenic activity including shoreline armoring, which disrupts connectivity between aquatic and terrestrial realms and artificially steepens the shore. Such effects may have adverse consequences for juvenile salmon, particularly Chinook ( O. tshawytscha) and chum ( O. nerka), which are known to rely on shallow, productive nearshore habitats for foraging and refuge from predators during their outmigration from natal streams to the sea. We developed snorkel methods to quantify feeding rates, movement rates, and path complexity of juvenile salmon along armored and unarmored shorelines in Puget Sound, WA, USA. We found that juvenile salmon had relatively high feeding rates along all shoreline types, but that path straightness and movement rates showed some variation between armored and unarmored sites. Feeding fish swam in more complex paths and were observed in larger schools than non-feeding fish, and path straightness and movement rate were negatively correlated with proportion of time feeding. Feeding behavior, school size, and movement rates also showed variation by species. Shoreline type (armored or unarmored) influenced juvenile salmon distribution, and unarmored shorelines appear to accommodate a greater diversity of movement patterns than armored shorelines. Our results show that juvenile salmon feed at high rates along armored and unarmored estuarine shorelines, thus decreased prey availability or altered prey resources are likely the most detrimental foraging effects of armoring in estuarine nearshore ecosystems. [ABSTRACT FROM AUTHOR]