scholarly journals The Expression of agrp1, A Hypothalamic Appetite-Stimulating Neuropeptide, Reveals Hydrodynamic-Induced Starvation in a Larval Fish

2018 ◽  
Vol 1 (1) ◽  
Author(s):  
L Koch ◽  
I Shainer ◽  
T Gurevich ◽  
R Holzman
Keyword(s):  
Sparus Aurata ◽  
Larval Fish ◽  
Mechanistic Explanation ◽  
Early Ontogeny ◽  
Larval Feeding ◽  
Feeding Rates ◽  
Fluid Forces ◽  
Water Viscosity ◽  
Hydrodynamic Environment

Abstract Larval fish suffer dramatic mortality in the days following transition to autonomous feeding, with over 90% of larvae being eliminated within a period of few weeks. Recent work has shown that the hydrodynamic environment experienced by recently-hatched larvae impedes their feeding rates even under high prey densities. Here, we quantified starvation through early ontogeny in Sparus aurata larvae (8–18 days post-hatching; DPH) and tested whether the emerging ontogenetic pattern is consistent with that expected one based on the hydrodynamic environment that these larvae experience. We screened three candidate genes agrp1, npy, and hsp70, whose expression was previously shown to respond to starvation in fish. Of the three genes, agrp1 was identified as a suitable indicator for starvation. Localization of agrp1 mRNA by whole-mount in-situ hybridization confirmed that, in S. aurata larvae, agrp1 is expressed only in the hypothalamus. Quantification of agrp1 mRNA using real-time PCR revealed that the expression of this gene is elevated in starved compared to fed larvae, and in younger (8 DPH) compared to older larvae (18 DPH). Manipulating the water viscosity to simulate the hydrodynamic conditions during the onset of the critical period led to increased agrp1 expression. These findings suggest that the hydrodynamic constraints on larval feeding lead to the starvation of small larvae. Further, they provide a mechanistic explanation for the “safe harbor” hypothesis, which postulates that larvae should allocate resources toward rapid linear growth to escape detrimental effects of dwelling in an environment where viscous fluid forces dominate.

scholarly journals Hydrodynamic regime determines the feeding success of larval fish through the modulation of strike kinematics

2017 ◽  
Vol 284 (1853) ◽  
pp. 20170235 ◽  
Author(s):  
Victor China ◽  
Liraz Levy ◽  
Alex Liberzon ◽  
Tal Elmaliach ◽  
Roi Holzman
Keyword(s):  
High Speed ◽  
Sparus Aurata ◽  
Larval Fish ◽  
Reynolds Numbers ◽  
Early Ontogeny ◽  
Hydrodynamic Regime ◽  
Physical Growth ◽  
Larval Feeding ◽  
Feeding Success ◽  
Order Of Magnitude

Larval fishes experience extreme mortality rates, with 99% of a cohort perishing within days after starting to actively feed. While recent evidence suggests that hydrodynamic factors contribute to constraining larval feeding during early ontogeny, feeding is a complex process that involves numerous interacting behavioural and biomechanical components. How these components change throughout ontogeny and how they contribute to feeding remain unclear. Using 339 observations of larval feeding attempts, we quantified the effects of morphological and behavioural traits on feeding success of Sparus aurata larvae during early ontogeny. Feeding success was determined using high-speed videography, under both natural and increased water viscosity treatments. Successful strikes were characterized by Reynolds numbers that were an order of magnitude higher than those of failed strikes. The pattern of increasing strike success with increasing age was driven by the ontogeny of traits that facilitate the transition to higher Reynolds numbers. Hence, the physical growth of a larva plays an important role in its transition to a hydrodynamic regime of higher Reynolds numbers, in which suction feeding is more effective.

scholarly journals Suction feeding performance and prey escape response interact to determine feeding success in larval fish

2019 ◽  
Author(s):  
Noam Sommerfeld ◽  
Roi Holzman
Keyword(s):  
Early Development ◽  
Escape Response ◽  
High Speed ◽  
Sparus Aurata ◽  
Larval Fish ◽  
Reynolds Numbers ◽  
Larval Performance ◽  
Larval Feeding ◽  
Large Prey ◽  
Feeding Success

AbstractThe survival of larval marine fishes during early development is strongly dependent on their ability to capture prey. Most larval fish capture prey by expanding their mouth cavity, generating a “suction flow” that draws the prey into their mouth. Larval fish dwell in a hydrodynamic regime of low Reynolds numbers, which has been shown to impede their ability to capture non-evasive prey. However, the marine environment is characterized by an abundance of evasive prey such as Copepods. These organisms can sense the hydrodynamic disturbance created by approaching predators and perform high-acceleration escape maneuvers. Using a 3D high-speed video system, we characterized the interaction between 8-33 day post hatchingSparus auratalarvae and prey from a natural zooplankton assemblage that contained evasive prey, and assessed the factors that determine the outcome of these interactions. Larvae showed strong selectivity for large prey that was moving prior to the initialization of the strike. As previously shown in studies with non-evasive prey, larval feeding success increased with increasing Reynolds numbers. However, larval feeding success was also strongly dependent on the prey’s escape response. Feeding success was lower for larger, more evasive prey, indicating that larvae might be challenged in capturing their preferred prey. The kinematics of successful strikes resulted in shorter response time but higher hydrodynamic signature available for the prey. Thus, despite being “noisier”, successful strikes on evasive prey depended on preceding the prey’s escape response. Our results show that larval performance, rather than larval preferences, determines their diet during early development.

scholarly journals Black Soldier Fly Larval Valorization Benefitting from Ex-Situ Fungal Fermentation in Reducing Coconut Endosperm Waste

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 275
Author(s):  
Chung Yiin Wong ◽  
Kunlanan Kiatkittipong ◽  
Worapon Kiatkittipong ◽  
Seteno K. O. Ntwampe ◽  
Man Kee Lam ◽  
...  
Keyword(s):  
Principal Component ◽  
Correlation Study ◽  
Statistical Correlation ◽  
Waste Reduction ◽  
Ex Situ ◽  
Larval Feeding ◽  
Rhizopus Oligosporus ◽  
Black Soldier Fly ◽  
The Cost

Oftentimes, the employment of entomoremediation to reduce organic wastes encounters ubiquitous shortcomings, i.e., ineffectiveness to valorize recalcitrant organics in wastes. Considering the cost-favorability, a fermentation process can be employed to facilitate the degradation of biopolymers into smaller organics, easing the subsequent entomoremediation process. However, the efficacy of in situ fermentation was found impeded by the black soldier fly larvae (BSFL) in the current study to reduce coconut endosperm waste (CEW). Indeed, by changing into ex situ fermentation, in which the fungal Rhizopus oligosporus was permitted to execute fermentation on CEW prior to the larval feeding, the reduction of CEW was significantly enhanced. In this regard, the waste reduction index of CEW by BSFL was almost doubled as opposed to in situ fermentation, even with the inoculation of merely 0.5 wt % of Rhizopus oligosporus. Moreover, with only 0.02 wt % of fungal inoculation size to execute the ex situ fermentation on CEW, it could spur BSFL growth by about 50%. Finally, from the statistical correlation study using principal component analysis, the presence of Rhizopus oligosporus in a range of 0.5–1.0 wt % was regarded as optimum to ferment CEW via ex situ mode, prior to the valorization by BSFL in reducing the CEW.

scholarly journals Are Microplastics Impairing Marine Fish Larviculture?—Preliminary Results with Argyrosomus regius

Water ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 104
Author(s):  
Diana Campos ◽  
Andreia C. M. Rodrigues ◽  
Rui J. M. Rocha ◽  
Roberto Martins ◽  
Ana Candeias-Mendes ◽  
...  
Keyword(s):  
Oxidative Damage ◽  
Fish Larvae ◽  
Feeding Activity ◽  
Early Ontogeny ◽  
Antioxidant Defenses ◽  
Nutritional Requirements ◽  
Larval Feeding ◽  
Argyrosomus Regius ◽  
And Performance ◽  
Aquaculture Facilities

The presence of small-sized (<300 µm) microplastics (MPs) in aquaculture facilities may threaten finfish hatchery, as their (in)voluntary ingestion by fish larvae may compromise nutritional requirements during early ontogeny, and consequently larval health and performance. Thus, we addressed the short-term effects (7 h) of polyethylene microplastics (0.1, 1.0, 10 mg/L, PE-MPs) in meagre larvae Argyrosomus regius (15 dph) in the presence/absence of food. Larval feeding behavior, oxidative stress status, neurotoxicity, and metabolic requirements were evaluated. Results showed that meagre larvae ingested PE-MPs regardless of their concentration, decreasing in the presence of food (Artemia metanauplii). The presence of PE-MPs compromised larval feeding activity at the highest concentration. Under starvation, exposed larvae activated the antioxidant defenses by increasing the total glutathione levels and inhibiting catalase activity, which seemed efficient to prevent oxidative damage. Such larvae also presented increased energy consumption potentially related to oxidative damage prevention and decreased neurotransmission. Biochemical responses of fed larvae showed a similar trend, except for LPO, which remained unaffected, except at 0.1 mg/PE-MPs/L. Our results suggest that small-sized MPs in finfish hatcheries may compromise larvae nutritional requirements, but at considerably higher levels than those reported in marine environments. Nevertheless, cumulative adverse effects due to lower MPs concentrations may occur.

Feeding rates of gilthead seabream (Sparus aurata), larvae on microcapsules

Aquaculture ◽  
1995 ◽  
Vol 134 (3-4) ◽  
pp. 257-268 ◽  
Author(s):  
M. Yúfera ◽  
C. Fernández-Díaz ◽  
E. Pascual
Keyword(s):  
Sparus Aurata ◽  
Gilthead Seabream ◽  
Feeding Rates

A Conceptual Model for the Estimation of the Sensitivity of Black Fly Larvae to Bacillus thuringiensis var. israelensis

1989 ◽  
Vol 46 (10) ◽  
pp. 1785-1792 ◽  
Author(s):  
Antoine Morin ◽  
Christian Back ◽  
Jacques Boisvert ◽  
Robert H. Peters
Keyword(s):  
Bacillus Thuringiensis ◽  
Feeding Rate ◽  
Standard Procedure ◽  
Dry Mass ◽  
Published Data ◽  
Contact Period ◽  
Larval Feeding ◽  
Feeding Rates ◽  
Black Fly ◽  
Proposed Model

Results from bioassays of a commercial formulation of Bacillus thuringiensis var. israelensis (Teknar HP-D) are combined with an empirical model of the feeding rate of larvae of a target species of black fly (Simulium venustum/verecundum) to develop a model relating the mortality of larvae to the amount of formulation ingested per unit mass of larvae (specific ingested dose). LD50 of Teknar HP-D was about 1 μg wet mass of Teknar per milligram dry mass of larvae, and independent of size of the larvae and seston concentration. Compared with standard assay analysis relating the mortality to the dose (milligrams per litre times seconds), the proposed model allowed more precise and replicable estimation of the effective dose. Reanalysis of published data on the potency of another Bti formulation (Teknar WDC), confirmed the superiority of the proposed model over the standard procedure. Susceptibility of larvae to particulate larvicides is mainly a function of the larval feeding rate. In addition to size of the larvae, temperature, and seston concentration, analysis of the model reveals that the length of the contact period and the variability of feeding rates among individual larvae are important factors determining the mortality rate following treatments.

scholarly journals Once upon a larva: revisiting the relationship between feeding success and growth in fish larvae

2014 ◽  
Vol 72 (2) ◽  
pp. 359-373 ◽  
Author(s):  
Pierre Pepin ◽  
Dominique Robert ◽  
Caroline Bouchard ◽  
John F. Dower ◽  
Marianne Falardeau ◽  
...  
Keyword(s):  
Growth Rates ◽  
Larval Fish ◽  
Fish Larvae ◽  
Fish Growth ◽  
Individual Growth ◽  
Growth Time ◽  
Feeding Rates ◽  
Average Growth ◽  
Fast Growing ◽  
Feeding Success

Abstract Variations in larval fish growth rates are largely the result of variability in biotic and abiotic characteristics of the feeding environment experienced by each individual. An assessment of an individual's overall feeding success (i.e. accumulation of utilizable organic matter) can best be achieved at the time of capture when the relationships among environment, short-term feeding success as defined by gut content and long-term feeding success as defined by accumulated growth can be contrasted. Here, we investigated the relationships between average growth, feeding success, and variability in individual growth and feeding rates across a range of taxa based on a synthesis of studies in which stomach content and otolith growth were measured in the same individuals. Instantaneous measures of feeding success were highly variable and demonstrated a positive yet somewhat limited association with growth rates across all taxa. The strength of the feeding-growth relationships among taxa, and cohorts within taxa, was reflected in the autocorrelation of individual growth rates, suggesting that stable growth was achieved through consistent feeding success. However, when viewed at the individual level, faster growth was achieved in individuals with more variable growth rates, and by inference more variable past feeding success. The dichotomy in these underlying relationships may point to the importance of stochastic events in the development of exceptional individuals in a population, and may be linked to how surplus energy is allocated to individual growth rates. The positive correlation found between feeding success and growth in all taxa is consistent with the growth-survival paradigm for the larval stage of fish. However, both the correlation between feeding success and growth and the serial correlation of growth time-series was greatest in fast-growing species, suggesting that the potential for an early “critical period” regulating survival varies among species, reaching a maximum in fast-growing fish.

scholarly journals The influence of sponge-dwelling gobies (Elacatinus horsti) on the feeding efficiency of their Caribbean tube sponge ( Aplysina sp.) hosts

2021 ◽  
Author(s):  
Megan J Siemann ◽  
Aldo Turco ◽  
Shannon D Brown ◽  
Rita BJ Peachey
Keyword(s):  
Food Availability ◽  
Marine Invertebrates ◽  
Sponge Species ◽  
Feeding Rates ◽  
Feeding Efficiency ◽  
In Situ Methods ◽  
Fluorescein Dye ◽  
Measure Estimate

Mutualistic associations between benthic marine invertebrates and reef taxa are common. Sponge-dwelling gobies benefit from protection within sponge tubes and greater food availability. Sponge-dwelling gobies are hypothesized to increase sponge pump rates by consuming polychaete parasites, but such increases have not yet been demonstrated. We investigated the association between sponge-dwelling gobies (Elacatinus horsti) and two species of tube sponge (Aplysina lacunosa and Aplysina archeri) in Bonaire, Caribbean Netherlands. We visually assessed goby presence in sponges and used in situ methods with fluorescein dye to measure estimate feeding rates via pump rates. Aplysina archeri were more likely to host a goby than A. lacunosa. For both sponge species, pump rates of tubes with gobies were higher on average than those of tubes without gobies. Our observations, therefore, suggest that E. horsti associations with Aplysina are likely mutualistic relationships in which sponges benefit from higher feeding rates when gobies are present.

scholarly journals Effects of Microplastics on the Feeding Rates of Larvae of a Coastal Fish: Direct Consumption, Trophic Transfer, and Effects on Growth and Survival

2021 ◽  
Author(s):  
Christine Uy ◽  
Darren Johnson
Keyword(s):  
Larval Fish ◽  
Trophic Transfer ◽  
Control Group ◽  
Feeding Rates ◽  
Lower Growth ◽  
Larval Phase ◽  
Coastal Fish ◽  
Growth And Survival ◽  
Low Concentrations ◽  
High Concentrations

Abstract Microplastics are now found throughout the world’s oceans, and although many organisms ingest microplastics, less is known about how plastics in seawater may affect key processes such as feeding rate, growth, and survival. We used a series of laboratory experiments to test whether microplastics in seawater affected the feeding rates of larvae of the California Grunion, Leuresthes tenuis. In addition, we tested whether trophic transfer of microplastics from zooplankton to larval fish can occur and affect growth and survival of fish. We measured feeding rates of grunion larvae at various concentrations of 75–90 µm and 125–250 µm polyethylene microplastics and under both still water and turbulent conditions. In these experiments, exposure to microplastics had modest effects on feeding rates, though responses may be somewhat complex. Low concentrations of microplastics increased feeding rates compared to the control, but at higher concentrations, feeding rates were indistinguishable from those in the control group though effects were small compared to natural variation in feeding rates among individual fish. Experiments to test for trophic transfer of microplastics revealed that grunion larvae that were fed brine shrimp exposed to high concentrations of microplastics had lower growth rates and elevated mortality rates. Overall, our results suggest that the direct effects of microplastics on feeding rates of California Grunion during the early larval phase are minor, while the trophic transfer of microplastics from zooplankton to larval fish may have significant effects on their growth and survival.

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