2024

Jump to: 2023, 2022

13 pages, 2291 KiB

Open AccessArticle

The Influence of Shelter Type and Coverage on Crayfish (Procambarus clarkii) Predation by Catfish (Silurus asotus): A Controlled Environment Study

by Mingguang Zhao, Guangpeng Feng, Haihua Wang, Chenchen Shen, Yilong Fu, Yanping Zhang, Haixin Zhang, Yuan Yao, Jianhua Chen and Weikang Xu

Animals 2024, 14(8), 1147; https://doi.org/10.3390/ani14081147 - 10 Apr 2024

Viewed by 306

Abstract

Procambarus clarkii is adept at using natural shelters and caves to evade attacks from predators. However, the concealment abilities and mechanisms of P. clarkii for different types of shelters under predation pressure have not yet been reported. In this study, laboratory experiments were [...] Read more.

Procambarus clarkii is adept at using natural shelters and caves to evade attacks from predators. However, the concealment abilities and mechanisms of P. clarkii for different types of shelters under predation pressure have not yet been reported. In this study, laboratory experiments were carried out to determine the effects of different coverages (25%, 50%, and 75%) and different combinations (I–VII) of three types of shelters (PVC pipes, water grass, and stone) on the predation rhythm, behavior, and abilities of Silurus asotus on P. clarkii. The results indicated that the predation of S. asotus on P. clarkii exhibited significant rhythmicity under shelter conditions, excluding PVC pipes, 75% stone, and combination VI. Among the three types of shelters, PVC pipes provided the strongest concealment, followed by stone and water grass. With the increase in shelter coverage, the anti-predation ability of P. clarkii continued to increase, and the optimal shade rate for water grass was 50%. In the different shelter combinations, the environmental complexity had little effect on the predation activity of S. asotus on P. clarkii. These findings demonstrated that the type and abundance of shelters in the wild environment can affect the predation rhythm and activities of S. asotus on P. clarkii. Full article

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2023

Jump to: 2024, 2022

14 pages, 1377 KiB

Open AccessArticle

Feeding Behavior Responses of the Small Copepod, Paracalanus parvus, to Toxic Algae at Different Concentrations

by Zixuan Ding, Xiaohong Sun, Yiming Qiao, Ying Liu and Jihua Liu

Animals 2023, 13(19), 3116; https://doi.org/10.3390/ani13193116 - 06 Oct 2023

Viewed by 882

Abstract

The feeding relationship between copepods and phytoplankton has immense ecological significance. This study investigated the feeding behavior of copepods by studying the feeding selectivity of Paracalanus parvus, a key small copepod species, using a high-speed camera. The feeding behavior of P. parvus [...] Read more.

The feeding relationship between copepods and phytoplankton has immense ecological significance. This study investigated the feeding behavior of copepods by studying the feeding selectivity of Paracalanus parvus, a key small copepod species, using a high-speed camera. The feeding behavior of P. parvus separately fed on three algae, Prorocentrum minimum, Alexandrium minutum, and Thalassiosira weissflogii, was studied at five different concentrations. The factors characterizing feeding behavior, including the beating frequency (BF), beating time (BT), and rejection behavior, were analyzed. The average BT and BF of P. parvus fed on toxic algae were significantly lower than those of copepods fed on nontoxic algae, indicating that the toxic algae negatively affected their feeding behavior. There were no significant differences in feed rejection among the three algae during the short period of experimentation, indicating that the rejection behavior was insignificant in the early period (within 20 min) of feeding on toxic algae. The feeding behavior was inhibited when the concentration reached 250 cells/mL. The BT was initially affected at increasing concentrations followed by the BF, and P. minimum and A. minutum reduced the BF at concentrations of 250 and 1000 cells/mL, respectively. Analysis of the average BFs revealed that P. parvus was more significantly affected by P. minimum containing diarrheal shellfish poison than by A. minutum containing paralytic shellfish poison. The BF of copepods fed on P. minimum was significantly lower than that of copepods fed on A. minutum at 250–500 cells/mL but was not significantly different from that at 1000 cells/mL. This indicated that the inhibitory effect of P. minimum on the feeding behavior was more significant at concentrations observed at the onset of red tide blooms (0.25–0.5 × 10² cells/mL), but insignificant at concentrations reaching those in advanced red tides (>10³ cells/mL). This study demonstrates that toxic dinoflagellates alter the feeding behavior of copepods and describes the variations in their feeding response to different algal species and concentrations. The findings provide crucial insights for further studies on the feeding relationship between copepods and phytoplankton and on functional assessment of plankton ecosystems. Full article

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14 pages, 4069 KiB

Open AccessArticle

Top-Down Effect of Arthropod Predator Chinese Mitten Crab on Freshwater Nutrient Cycling

by Lin Wang, Hongjun Liu, Francisco Carvalho, Yunru Chen, Linshiyu Lai, Jiachun Ge, Xingjun Tian and Yunchao Luo

Animals 2023, 13(14), 2342; https://doi.org/10.3390/ani13142342 - 18 Jul 2023

Viewed by 919

Abstract

Aquatic litter decomposition is highly dependent on contributions and interactions at different trophic levels. The invasion of alien aquatic organisms like the channeled apple snail (Pomacea canaliculata) might lead to changes in the decomposition process through new species interactions in the [...] Read more.

Aquatic litter decomposition is highly dependent on contributions and interactions at different trophic levels. The invasion of alien aquatic organisms like the channeled apple snail (Pomacea canaliculata) might lead to changes in the decomposition process through new species interactions in the invaded wetland. However, it is not clear how aquatic macroinvertebrate predators like the Chinese mitten crab (Eriocheir sinensis) will affect the nutrient cycle in freshwater ecosystems in the face of new benthic invasion. We used the litter bag method to explore the top-down effect of crabs on the freshwater nutrient cycle with the help of soil zymography (a technology previously used in terrestrial ecosystems). The results showed significant feeding effects of crabs and snails on lotus leaf litter and cotton strips. Crabs significantly inhibited the intake of lotus litter and cotton strips and the ability to transform the environment of snails by predation. Crabs promoted the decomposition of various litter substrates by affecting the microbial community structure in the sediment. These results suggest that arthropod predators increase the complexity of detrital food webs through direct and indirect interactions, and consequently have an important impact on the material cycle and stability of freshwater ecosystems. This top-down effect makes macrobenthos play a key role in the biological control and engineering construction of freshwater ecosystems. Full article

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11 pages, 908 KiB

Open AccessArticle

Risk Predictability in Early Life Shapes Personality of Mosquitofish in Adulthood

by Mengdi Si, Wenwen Zhang, Chunlin Li, Li Su and Xinyu Zhang

Animals 2023, 13(7), 1214; https://doi.org/10.3390/ani13071214 - 30 Mar 2023

Viewed by 1209

Abstract

Animal personality is of great ecological and evolutionary significance and has been documented in many animal taxa. Despite genetic background, personality might be prominently shaped by external environments, and it is significant to explore the environmental factors that influence the ontogeny of animal [...] Read more.

Animal personality is of great ecological and evolutionary significance and has been documented in many animal taxa. Despite genetic background, personality might be prominently shaped by external environments, and it is significant to explore the environmental factors that influence the ontogeny of animal personality in early life. Here, we reared newborn mosquitofish Gambusia affinis under different treatments of risk predictability (i.e., no risks, unpredictable risks, risks at 5 min after feeding and risks at 2 h after feeding) and measured their two personality traits at sexual maturity. We measured the behavioral repeatability, correlation between behavioral characteristics, and the impact of risk predictability. We found that the fish showed repeatability in exploration in all risk treatments, as well as repeatability in shyness under predictable risks. When growing up in risk treatments, no matter predictable or unpredictable, shyness and exploration showed a negative correlation, suggesting a behavioral syndrome between the two behavioral traits. The fish reared under predictable risks were less explorative than those under unpredictable risks, while there were no differences in shyness among treatments. Besides, smaller fish were bolder and more explorative than larger ones. Our findings imply that risk predictability in early life may play an important role in shaping animal personality and modifying the average behavioral levels. Full article

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16 pages, 3885 KiB

Open AccessArticle

Effect of Kisspeptin-Type Neuropeptide on Locomotor Behavior and Muscle Physiology in the Sea Cucumber Apostichopus japonicus

by Xueying Guo, Libin Zhang and Kang Xiao

Animals 2023, 13(4), 705; https://doi.org/10.3390/ani13040705 - 17 Feb 2023

Cited by 2 | Viewed by 1537

Abstract

Kisspeptins are neuropeptides encoded by the kiss1 gene, and little is known about them outside the vertebrate lineage. Two kisspeptin-type neuropeptides (KPs) have been discovered in Apostichopus japonicus (AjK1 and AjK2), an edible sea cucumber, and have been linked to reproductive and metabolic [...] Read more.

Kisspeptins are neuropeptides encoded by the kiss1 gene, and little is known about them outside the vertebrate lineage. Two kisspeptin-type neuropeptides (KPs) have been discovered in Apostichopus japonicus (AjK1 and AjK2), an edible sea cucumber, and have been linked to reproductive and metabolic regulation. In this study, we evaluated how KPs affected locomotor behavior in one control group and two treatment groups (AjK1 and AjK2). We discovered that AjK1 had a significant dose effect, primarily by shortening the stride length and duration of movement to reduce the sea cucumber movement distance, whereas AjK2 had little inhibitory effect at the same dose. The levels of phosphatidylethanolamine (PE), phosphatidylcholine (PC), uridine, glycine, and L-serine in the longitudinal muscle of A. japonicus treated with AjK1 differed significantly from those of the control, which may explain the observed changes in locomotor behavior. Treatment with AjK2 induced changes in aspartate levels. Our results imply that AjK1 is more likely than AjK2 to have a role in the regulation of A. japonicus locomotion. Full article

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15 pages, 1230 KiB

Open AccessArticle

Two Are Better Than One: Integrating Spatial Geometry with a Conspicuous Landmark in Zebrafish Reorientation Behavior

by Greta Baratti and Valeria Anna Sovrano

Animals 2023, 13(3), 537; https://doi.org/10.3390/ani13030537 - 03 Feb 2023

Cited by 1 | Viewed by 1578

Abstract

Within bounded environments of a distinctive shape, zebrafish locate two geometrically equivalent corner positions, based on surface metrics and left-right directions. For instance, the corners with a short surface right/long surface left cannot be distinguished as unique spatial locations unless other cues break [...] Read more.

Within bounded environments of a distinctive shape, zebrafish locate two geometrically equivalent corner positions, based on surface metrics and left-right directions. For instance, the corners with a short surface right/long surface left cannot be distinguished as unique spatial locations unless other cues break the symmetry. By conjoining geometry with a conspicuous landmark, such as a different-color surface, one of the two geometric twins will have a short different-colored surface right, becoming identifiable. Zebrafish spontaneously combine a rectangular white arena’s shape with a blue wall landmark, but only when this landmark is near the target corner; when far, that cue triggers a steady attractiveness bias. In this study, we trained zebrafish to use a blue wall landmark in conjunction with a rectangular-shaped arena, providing them rewards over time. We found that trained zebrafish learned to locate the target corner, regardless of the landmark’s length and distance, overcoming the attractiveness bias. Zebrafish preferred geometry after removing the landmark (geometric test), but not if put into conflict geometry and landmark (affine transformation). Analysis on movement patterns revealed wall-following exploration as a consistent strategy for approaching the target corner, with individual left-right direction. The capacity of zebrafish to handle different sources of information may be grounds for investigating how environmental changes affect fish spatial behavior in threatened ecosystems. Full article

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2022

Jump to: 2024, 2023

13 pages, 1925 KiB

Open AccessArticle

The Multiple Influences of Natural Farming Environment on the Cultured Population Behavior of Kuruma Prawn, Penaeus japonicus

by Wenzhi Cheng, Heqian Zhang, Panpan Wang, Yiming Wei, Chuanxi Chen, Yiling Hou, Xiaojie Deng, Siqi Li, Shengyao Sun, Qisi Cai, Yong Mao and Xiangrong Liu

Animals 2022, 12(23), 3383; https://doi.org/10.3390/ani12233383 - 01 Dec 2022

Cited by 1 | Viewed by 1351

Abstract

Recent years have witnessed a tremendous development in shrimp farming around the world, which, however, has raised a variety of issues, possibly due to a lack of knowledge of shrimp behavior in farms. This study focused on the relationship between shrimp behavior and [...] Read more.

Recent years have witnessed a tremendous development in shrimp farming around the world, which, however, has raised a variety of issues, possibly due to a lack of knowledge of shrimp behavior in farms. This study focused on the relationship between shrimp behavior and the various factors of natural farming environment through situ surveys, as distinguished from the majority of laboratory studies on shrimp behavior. In the survey, the behaviors of kuruma prawn (Penaeus japonicus) were investigated in the groups of swimming in the water, crawling on the sand, resting on the sand, and hiding in the sand, followed by the quantification of the sex ratio, water quality, density, and light intensity. The results showed the average proportions of resting, hiding, crawling, and swimming activities of 69.87%, 20.85%, 8.24%, and 1.04%, respectively, of P. japonicus. The behavior of hiding, resting, and crawling is significantly affected by the sex ratio of the shrimp (p < 0.05). The proportions of hiding behavior exhibited a negative connection with density and a positive connection with light intensity, while the proportions of resting behavior showed the opposite according to both Pearson correlation analysis and multiple linear regression analysis. The light intensity was the only factor that significantly influenced the swimming behavior, in which the probability of the swimming behavior was reduced from 48% to 5% when light intensity varied from 0 to 10 lx, as determined by the generalized linear model. It could be speculated that P. japonicus prefers a tranquil environment. Female shrimp might exhibit less aggression and more adventure compared to male shrimp. The findings suggested light intensity, followed by density, as the most crucial element influencing the behavior of P. japonicus in the culture environment. These findings will contribute to the comprehension of the behavior of P. japonicus and provide a novel perspective for the formulation of its culture management strategy. Full article

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12 pages, 2376 KiB

Open AccessArticle

The Relationship between Burrow Opening Dimensions and Biomass of Intertidal Macroinvertebrates by Feeding Mode (Surface Deposit Feeders vs. Suspension Feeders)

by Bon Joo Koo, Jaehwan Seo and Min Seong Jang

Animals 2022, 12(20), 2878; https://doi.org/10.3390/ani12202878 - 21 Oct 2022

Viewed by 1360

Abstract

Biomass and abundance are fundamental parameters in ecology, conservation biology, and environmental impact assessment. Distinguishing features, such as burrow openings and feeding pellets, made by different intertidal macroinvertebrate species on the surface are used as proxies to establish the abundance of intertidal macroinvertebrates. [...] Read more.

Biomass and abundance are fundamental parameters in ecology, conservation biology, and environmental impact assessment. Distinguishing features, such as burrow openings and feeding pellets, made by different intertidal macroinvertebrate species on the surface are used as proxies to establish the abundance of intertidal macroinvertebrates. This study investigated the feasibility of estimating biomass from the burrow opening dimensions as a proxy. We analyzed the relationship between the burrow opening dimensions and body weights of intertidal macroinvertebrates and compared surface deposit feeders with suspension feeders. Regression analysis evaluated the relationship between burrow opening diameter, body size, and biomass. The diameters of surface deposit feeder burrow openings were significantly related to biomass, but this was not the case for suspension feeders. Our results indicate that burrow opening dimensions can be used as a proxy to estimate the biomass of surface deposit feeders. However, additional studies are needed to clarify further the relationship between the burrow opening diameter and biomass of the suspension feeders. This is a preliminary study to spatially quantify the biomass of intertidal macroinvertebrates by extracting the dimension of burrow openings from drone images through object detection tools. Full article

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13 pages, 2349 KiB

Open AccessArticle

Differences in Agonistic Behavior and Energy Metabolism between Male and Female Swimming Crab Portunus trituberculatus Based on the Analysis of Boldness

by Xianpeng Su, Boshan Zhu, Ziwen Ren and Fang Wang

Animals 2022, 12(18), 2363; https://doi.org/10.3390/ani12182363 - 10 Sep 2022

Cited by 1 | Viewed by 1568

Abstract

Individual differences in metabolism and agonistic behavior have been a key research area in evolution and ecology recently. In this study, we investigated the boldness of swimming crabs Portunus trituberculatus and explored the agonistic behavior between female and male crabs, specifically examining competitions [...] Read more.

Individual differences in metabolism and agonistic behavior have been a key research area in evolution and ecology recently. In this study, we investigated the boldness of swimming crabs Portunus trituberculatus and explored the agonistic behavior between female and male crabs, specifically examining competitions between bold females vs. bold males (BF–BM), bold females vs. shy males (BF–SM), shy females vs. shy males (SF–SM), and shy females vs. bold males (SF_BM) and its relationship with energy metabolism. The main results revealed the following: There was no significant difference in boldness between females and males, while there were more bold individuals than shy in both females and males. Bold individuals initiated significantly more fights than shy individuals, and male initiators won significantly more fights than female initiators. The duration and intensity of fight between bold individuals was significantly higher than fights between shy individuals. For males, the concentration of glucose in the hemolymph was significantly higher in shy crabs than bold crabs, while there was no significant difference between shy and bold individuals in females. After fighting, the concentration of glycogen in claws was lower than that before fighting, and the concentrations of glucose and lactate in hemolymph were significantly higher after fighting than before. We found that the fighting willingness and ability were higher in male crabs than females and higher in bold crabs than shy. Fighting ability varied between sexes and was influenced by boldness and energy state. Full article

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11 pages, 1782 KiB

Open AccessArticle

Salinity-Driven Changes in Behavioral Responses of Catadromous Eriocher sinensis

by Chenchen Shen, Ruifang Wang, Guangpeng Feng, Feng Zhao, Tao Zhang and Xiaorong Huang

Animals 2022, 12(17), 2244; https://doi.org/10.3390/ani12172244 - 30 Aug 2022

Cited by 2 | Viewed by 1472

Abstract

The effects of salinity on behavior are far-reaching, and Eriocheir sinensis showed disparate behaviors under different salinity conditions. Female crabs were more active in saline water, especially low salinity stress, which is beneficial for female crabs to escape from the low-salinity environment quickly. [...] Read more.

The effects of salinity on behavior are far-reaching, and Eriocheir sinensis showed disparate behaviors under different salinity conditions. Female crabs were more active in saline water, especially low salinity stress, which is beneficial for female crabs to escape from the low-salinity environment quickly. Then, antennal movement indicated that antennae might be the main osmoreceptors in E. sinensis, and 65 min might be a good starting time for salinity stress to analyze osmoregulation in crabs. Interestingly, E. sinensis had obvious behavioral differences in the high and low salinity stress, and behaviors were more intense in a salinity dip from salinity 18 to salinity 0. This study analyzed the osmoregulatory process of catadromous E. sinensis in different salinity from the point of osmoregulatory organ and behavioral response. These results will provide a scientific basis for the osmoregulatory mechanism of E. sinensis, which are conducive to evaluating and analyzing the impact of saltwater intrusion in the Yangtze River estuary on resource fluctuation. Full article

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16 pages, 3817 KiB

Open AccessArticle

Influences of Substrate Grain Size on the Burrowing Behavior of Juvenile Meretrix meretrix

by Changsheng Zhang, Suyan Xue, Jiaqi Li, Jinghui Fang, Lulei Liu, Zhanfei Ma, Wenhan Yu, Haonan Zhuang and Yuze Mao

Animals 2022, 12(16), 2094; https://doi.org/10.3390/ani12162094 - 16 Aug 2022

Cited by 6 | Viewed by 1568

Abstract

The substrate is the key environmental factor that affects the growth, survival, population and distribution of dwelling mollusks in mudflat settings. To clarify the effect of the substrate grain size on soft substrate preference, burrowing ability and behavior during the selection process of [...] Read more.

The substrate is the key environmental factor that affects the growth, survival, population and distribution of dwelling mollusks in mudflat settings. To clarify the effect of the substrate grain size on soft substrate preference, burrowing ability and behavior during the selection process of juvenile Meretrix meretrix, four different grain size substrates (coarse sand, medium sand, fine sand, and natural substrate) were set up for comparison. The results indicated that: (1) the burrowing ability of juvenile specimens in fine sand was the strongest; (2) the degree (from high to low) of the juvenile’s preference for the four substrates was in the order of fine sand > natural substrate > medium sand > coarse sand; and (3) the selection process of the substrate by the juveniles could be divided into four stages: preparation, selection, burrowing and end stages. These stages showed the behavioral characteristics of a longer selection time and higher percentage of movement in coarse sand. Therefore, our results demonstrated that sea areas or ponds with fine sand as the main component are more suitable for stock enhancement with M. meretrix. These results provide basic data for habitat selection and suitability evaluations for the aquaculture of M. meretrix. Full article

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11 pages, 2105 KiB

Open AccessArticle

Transcriptomic and Behavioral Studies of Small Yellow Croaker (Larimichthys polyactis) in Response to Noise Exposure

by Xuguang Zhang, Jun Zhou, Wengang Xu, Wei Zhan, Huafeng Zou and Jun Lin

Animals 2022, 12(16), 2061; https://doi.org/10.3390/ani12162061 - 13 Aug 2022

Cited by 4 | Viewed by 1962

Abstract

Noise has the potential to induce physiological stress in marine fishes, which may lead to all sorts of ecological consequences. In the current study, we used the RNA-sequencing (RNA-seq) method to sequence the whole transcriptome of the brain in small yellow croaker ( [...] Read more.

Noise has the potential to induce physiological stress in marine fishes, which may lead to all sorts of ecological consequences. In the current study, we used the RNA-sequencing (RNA-seq) method to sequence the whole transcriptome of the brain in small yellow croaker (Larimichthys polyactis). The animals were exposed to a mix of noises produced by different types of boat played back in a tank, then the brain tissues were collected after the fish had been exposed to a 120 dB noise for 0.5 h. In total, 762 differently expressed genes (DEGs) between the two groups were identified, including 157 up regulated and 605 down regulated genes in the noise exposure group compared with the control group. Gene ontology (GO) enrichment analysis indicated that the most up regulated gene categories included synaptic membranes, receptor-mediated endocytosis and the neurotransmitter secretion process. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways found that endocytosis, cell adhesion molecules and the extracellular matrix (ECM) receptor interaction pathway were over-represented. Specifically, ECM-related genes, including lamin2, lamin3, lamin4, coll1a2, coll5a1 and col4a5 were down regulated in the noise exposure group, implying the impaired composition of the ECM. In addition, the behavioral experiment revealed that L. polyactis exhibited avoidance behaviors to run away from the noise source at the beginning of the noise exposure period. At the end of the noise exposure period, L. polyactis kept motionless on the surface of the water and lost the ability to keep their balance. Taken together, our results indicate that exposure to noise stress contributes to neurological dysfunction in the brain and impaired locomotor ability in L. polyactis. Full article

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13 pages, 3597 KiB

Open AccessArticle

Analysis of Movements and Behavior of Bighead Carps (Hypophthalmichthys nobilis) Considering Fish Passage Energetics in an Experimental Vertical Slot Fishway

by Junjun Tan, Zhenbiao Liu, Yu Wang, Yuanyang Wang, Senfan Ke and Xiaotao Shi

Animals 2022, 12(13), 1725; https://doi.org/10.3390/ani12131725 - 04 Jul 2022

Cited by 3 | Viewed by 1712

Abstract

An understanding of fish movement behavior in response to flow field variables is important for exploring the hydrodynamic strategies of fish in fish passages. In this paper, bighead carps were taken as an example. The fish movement behavior response to water flow field [...] Read more.

An understanding of fish movement behavior in response to flow field variables is important for exploring the hydrodynamic strategies of fish in fish passages. In this paper, bighead carps were taken as an example. The fish movement behavior response to water flow field information by means of estimating the energetic expenditure using an IBM approach in an experimental fishway was investigated. Fish swimming velocity, drag force, and energy expenditure were analyzed in varied flow conditions related to hydraulic variables, including velocity (V), turbulent kinetic energy (TKE), and strain rate (SR). The result indicated that the fish will require more energy in high TKE zones. This study provides a reference for optimizing the design of fish passages and fisheries management. This method can be applied to assess the efficiency of fish bypass structures and conduct fish survival studies. Full article

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13 pages, 1708 KiB

Open AccessArticle

What Forms, Maintains, and Changes the Boldness of Swimming Crabs (Portunus trituberculatus)?

by Boshan Zhu, Xianpeng Su, Weiping Yu and Fang Wang

Animals 2022, 12(13), 1618; https://doi.org/10.3390/ani12131618 - 23 Jun 2022

Cited by 3 | Viewed by 1702

Abstract

Boldness of personality is an important theme in animal behavior and has significant ecological and evolutionary consequences. Studies on boldness in crustaceans typically focus on their behavior, while relatively few studies have focused on the formation and maintenance of and change in boldness, [...] Read more.

Boldness of personality is an important theme in animal behavior and has significant ecological and evolutionary consequences. Studies on boldness in crustaceans typically focus on their behavior, while relatively few studies have focused on the formation and maintenance of and change in boldness, such as energy metabolism and neurotransmission. In this study, we measured the boldness of swimming crabs (Portunus trituberculatus) and analyzed the relationship between boldness and oxygen consumption rate, energy concentration, and the relative expression of energy-metabolism-related and 5-HT genes in mRNA. The results showed that boldness remained stable across repeated tests but changed under dangerous conditions. Swimming crabs could be divided into bold and shy individuals. Bold individuals consumed oxygen at a significantly higher rate than shy individuals. Lactate and glucose concentrations in hemolymph were significantly lower in bold individuals than in shy individuals, and mRNA relative expression of Na⁺/K⁺-ATPase and 5-HT genes was significantly higher in bold than in shy individuals. Preliminary results indicate that energy metabolism and neurotransmitters may underlie the formation and maintenance of personality characteristics of swimming crabs. Swimming crabs also exhibit behavioral flexibility in order to cope with risks. This may be an adaptation to their complex environments. Full article

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10 pages, 929 KiB

Open AccessArticle

Spatial Learning of Individual Cichlid Fish and Its Effect on Group Decision Making

by Jiaxing Long and Shijian Fu

Animals 2022, 12(10), 1318; https://doi.org/10.3390/ani12101318 - 21 May 2022

Cited by 3 | Viewed by 2069

Abstract

Learning and memory abilities and their roles in group decision-making have important ecological relevance in routine activities such as foraging and anti-predator behaviors in fish species. The aims of the present study were to explore individual spatial learning abilities of juvenile cichlids ( [...] Read more.

Learning and memory abilities and their roles in group decision-making have important ecological relevance in routine activities such as foraging and anti-predator behaviors in fish species. The aims of the present study were to explore individual spatial learning abilities of juvenile cichlids (Chindongo demasoni) in a foraging context, and to explore the influence of heterogeneity of memory information among group members on group performance in a six-arm radiation maze. In the context of an association between landmarks and food, learning ability was evaluated by the speed and accuracy of reaching the arm with food during seven days of reinforcement, and memory retention was tested at intervals of 2, 5, 8 and 11 days of detraining. Then, the speed and accuracy of an eight-member group with different proportions of memory-trained fish were measured. Both speed and accuracy of individual fish improved significantly and linearly in the first five days of training and leveled off between five and seven days, with values 60% shorter (in speed) and 50% higher (in accuracy) compared to those of the first day. Neither speed nor accuracy showed any decrease after 11 days of detraining, suggesting memory retention of the spatial task. When measured in a group, the speed and accuracy of the majority of the group (more than half) in reaching the arm with food changed linearly with an increasing ratio of trained members. This shows that cichlids can acquire associative learning information through a training process, and group behavior of cichlids seems not likely be determined by a minority of group members under a foraging context. Full article

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18 pages, 482 KiB

Open AccessArticle

Sex Differences in Mate Choice Preference Characteristics of Aequidens rivulatus

by Haixia Li, Jie Wang, Xu Zhang, Yu Hu, Qinglin Cai, Ying Liu and Zhen Ma

Animals 2022, 12(9), 1205; https://doi.org/10.3390/ani12091205 - 07 May 2022

Cited by 1 | Viewed by 16405

Abstract

The mating roles of males and females, to a certain extent, are dynamic and variable. Several factors influence the mate choice process. Nonetheless, the main preference features have not yet been fully understood in Aequidens rivulatus. In this study, because of its [...] Read more.

The mating roles of males and females, to a certain extent, are dynamic and variable. Several factors influence the mate choice process. Nonetheless, the main preference features have not yet been fully understood in Aequidens rivulatus. In this study, because of its natural pairing characteristics, A. rivulatus was selected to explore the mate choice preferences of different sexes. Specifically, male and female behavioral performances were described and quantified through a “no-choice paradigm” during mate choice. A total of 12 behavioral performances were defined in male mate choice (experiment 1), whereas 14 behavioral performances were defined in female mate choice (experiment 2). According to the obtained results, unselected females did not display any proactive behaviors in experiment 1, whereas unselected males exhibited proactive behaviors in experiment 2, including quivering, nipping, tail beating, swimming up and down, and aggression. It was also found that both male and female individuals tend to express dislike rather than like. Those behaviors with higher frequencies (e.g., quivering) often mean less energy expenditure, thus easier repeatability. Moreover, principal component analysis (PCA) was employed to extract and identify mate choice preference features. Preliminary results indicated that male preferences for a mate were mainly associated with body size, behavioral intention, and appearance, whereas the intensity of female preferences was in the order of body size, appearance, and behavioral intention. In addition, sex hormone levels were associated with mate choices. Full article

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11 pages, 1304 KiB

Open AccessArticle

Preference for Shelters at Different Developmental Stages of Chinese Mitten Crab (Eriocheir sinensis)

by Chunbo Li, Chenchen Shen, Guangpeng Feng, Xiaorong Huang and Xincang Li

Animals 2022, 12(7), 918; https://doi.org/10.3390/ani12070918 - 03 Apr 2022

Cited by 7 | Viewed by 2222

Abstract

A shelter is a good habitat for aquatic organisms, which could aid in avoiding cannibalism and facilitate predation. Chinese Mitten Crab (Eriocheir sinensis) is an important aquaculture species with troglodytism and nocturnal habit. To clarify the preference for shelters at different [...] Read more.

A shelter is a good habitat for aquatic organisms, which could aid in avoiding cannibalism and facilitate predation. Chinese Mitten Crab (Eriocheir sinensis) is an important aquaculture species with troglodytism and nocturnal habit. To clarify the preference for shelters at different developmental stages of E. sinensis, different shelters (mud, sand, grass and rocks) were selected for comparison. These results indicated that juvenile crabs had a significant preference for grass; button-sized crabs preferred to hide in mud; and the favorite shelters for parent crabs were rocks, followed by mud. E. sinensis in three stages all showed concealing behavior. The concealing behavior of juvenile crabs was the most significant, followed by button-sized and parent crabs. Additionally, E. sinensis held a low hiding rate at night but a high hiding rate during the daytime due to nocturnal habits. These findings will help to better understand the habits of E. sinensis and provide a reference for resource restoration, habitat construction and the restoration of E. sinensis. Full article

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18 pages, 8815 KiB

Open AccessArticle

Evaluation of Volitional Swimming Behavior of Schizothorax prenanti Using an Open-Channel Flume with Spatially Heterogeneous Turbulent Flow

by Minne Li, Ruidong An, Min Chen and Jia Li

Animals 2022, 12(6), 752; https://doi.org/10.3390/ani12060752 - 17 Mar 2022

Cited by 2 | Viewed by 2062

Abstract

Effective fishway design requires knowledge of fish swimming behavior in streams and channels. Appropriate tests with near-natural flow conditions are required to assess the interaction between fish behavior and turbulent flows. In this study, the volitional swimming behavior of S. prenanti was tested [...] Read more.

Effective fishway design requires knowledge of fish swimming behavior in streams and channels. Appropriate tests with near-natural flow conditions are required to assess the interaction between fish behavior and turbulent flows. In this study, the volitional swimming behavior of S. prenanti was tested and quantified in an open-channel flume with three (low, moderate, and high) flow regimes. The results showed that, when confronted with alternative flow regimes, S. prenanti preferred to select regions with low flow velocities (0.25–0.50 m/s) and turbulent kinetic energy (<0.05 m²/s²) for swimming, while avoiding high-turbulence areas. Moreover, S. prenanti primarily employed steady swimming behavior to search for flow velocities lower than the average current to conserve energy in low- and moderate-flow regimes. It is hypothesized that in regions with higher flow velocities, fish may change their swimming strategy from energy conservation to time conservation. Additionally, the average and maximum burst speeds of S. prenanti were 2.63 ± 0.37 and 3.49 m/s, respectively, which were 2.21- and 2.28-fold higher than the average (1.19 m/s) and maximum (1.53 m/s) burst speeds estimated from the enclosed swim chamber for fish of similar length. This study contributes a novel research approach that provides more reliable information about fish volitional swimming behavior in natural habitats, as well as recommendations for hydraulic criteria for fishways and the identification of barriers to fish migrations. Full article

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13 pages, 1868 KiB

Open AccessArticle

The Effect of Intruder Density on Territoriality and Dominance in Male Swimming Crab (Portunus trituberculatus)

by Boshan Zhu, Hanzun Zhang, Yunliang Lu, Fang Wang and Dapeng Liu

Animals 2022, 12(3), 314; https://doi.org/10.3390/ani12030314 - 27 Jan 2022

Cited by 2 | Viewed by 2399

Abstract

Territorial behavior of animals is affected by numerous factors, one being the number of intruders. The swimming crab (Portunus trituberculatus), an important commercial and ecological species on the continental shelf of Asia, usually needs to defend its territory from intrusion by [...] Read more.

Territorial behavior of animals is affected by numerous factors, one being the number of intruders. The swimming crab (Portunus trituberculatus), an important commercial and ecological species on the continental shelf of Asia, usually needs to defend its territory from intrusion by other crabs, especially in habitats with high densities of conspecifics. To clarify the underlying patterns of how P. trituberculatus protects its territory, we assessed the territorial behavior of occupant crabs (territory holders) when presented with different numbers of intruders using an indoor observation system. We calculated the territory size of the occupants and quantified their behavioral responses to intruders. With an increased number of intruders, the territory size the occupants owned significantly decreased, and their behavior adjusted accordingly. Besides, the territorial behavior score, reflecting the territoriality of crab, decreased significantly. Furthermore, in a high density group that had seven intruders, the occupants showed a higher dominance hierarchy than the intruders, indicating the ascendancy of occupants in territorial competition with intruders. These results revealed that as the number of intruders increased, the territory size of P. trituberculatus shrunk because the fight for territory became more intense. Full article

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18 pages, 14188 KiB

Open AccessArticle

A Detailed Analysis of the Effect of Different Environmental Factors on Fish Phototactic Behavior: Directional Fish Guiding and Expelling Technique

by Jiawei Xu, Wenlu Sang, Huichao Dai, Chenyu Lin, Senfan Ke, Jingqiao Mao, Gang Wang and Xiaotao Shi

Animals 2022, 12(3), 240; https://doi.org/10.3390/ani12030240 - 19 Jan 2022

Cited by 5 | Viewed by 2527

Abstract

Optimization of light-based fish passage facilities has attracted extensive attention, but studies under the influence of various environmental factors are scarce. We established a novel experimental method to measure the phototactic behavior of Schizothorax waltoni. The results showed that S. waltoni preferred [...] Read more.

Optimization of light-based fish passage facilities has attracted extensive attention, but studies under the influence of various environmental factors are scarce. We established a novel experimental method to measure the phototactic behavior of Schizothorax waltoni. The results showed that S. waltoni preferred the four light colors in the order green, blue, red, and yellow. The increased flow velocity intensified the positive and negative phototaxis of fish under different light environments, while an increase in the water temperature aroused the escape behavior. The escape behavior of fish in red and yellow light and the phototaxis behavior in green and blue light intensified as the light intensity exceeded the phototaxis threshold and continued to increase. Thus, red or yellow light greater than the phototaxis threshold can be used to move fish away from high-turbulent flows or polluted waters, while green or blue light can be used to guide them to fish passage entrance or ideal habitats. This study provides scientific evidence and application value for restoring fish habitats, fish passages, and fisheries. Full article

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