scholarly journals Importance of prey size on investigating prey availability of larval fishes

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0251344
Author(s):  
Yu-Hsuan Huang ◽  
Hsiao-Hang Tao ◽  
Gwo-Ching Gong ◽  
Chih-hao Hsieh

Prey availability plays an important role in determining larval fish survival. Numerous studies have found close relationships between the density of mesozooplankton and larval fishes; however, emerging studies suggest that small-size zooplankton are more important prey for some larval fish species. One arising question is whether the size of zooplankton determines the relationship between zooplankton and larval fish community in natural environments. To address this question, we collected small-size (50–200 μm) zooplankton, mesozooplankton (> 330 μm), and larval fish using three different mesh-size (50, 330, 1000 μm, respectively) nets in the East China Sea, and examined their relationships in density. Both meso- and small-size zooplankton densities showed positive relationships with larval fish density, while the relationship is much stronger for the small-size zooplankton. Specifically, the smallest size classes (50–75 and 75–100 μm) of small-size zooplankton showed the highest positive relationships with larval fish density. Temperature, salinity, and chlorophyll-a concentration did not significantly explain larval fish density. Based on these findings, we demonstrate the importance of considering prey size when investigating prey availability for larval fishes.

Author(s):  
Diana Medina Contreras ◽  
Jaime Cantera ◽  
Eugenia Escarria ◽  
Luz M Mejía Ladino

The density, taxonomic composition, and spatial and temporal distribution of the estuarine ichthyoplankton of Bahía Málaga (Pacific coast of Colombia) are described, as well as the relationship between biological parameters and some physicochemical variables. Samples were collected at 12 stations along the principal navigation canal; these samples were taken in four areas following the design of Barletta-Bergan. Surface sweeps were carried out with a conical-cylindrical net (mesh size 500 µm, mouth diameter 0.6 m, length 3.5 m). Salinity and temperature were measured before each sweep. A total of 69019 larvae/1000 m³, representing 23 families, 36 genera and 40 species were collected during monthly sampling from September, 2009 to February, 2010. Carangidae (39.0%) was the most abundant family, followed by Sciaenidae (27.1%) and Engraulidae (20.1%). The most frequent families were Sciaenidae (26.6%), followed by Carangidae (22.8%) and Engraulidae (14.7%) which are important families in larval fish assemblages in tropical estuaries. Eighty percent of total density was provided by six species, of which Seriola morphotype 1 (Carangidae) and Cetengraulis mysticetus (Engraulidae) were the most abundant and dominant. No correlation was found between density and salinity (Spearman, R = 0.23) or temperature (Spearman, R = 0.51). Analysis of spatial and temporal variations of larval density shows significant differences among the months sampled (Anova, p = 0.0029; p < 0.05), but not among areas (Anova, p = 0.078), suggesting that Bahía Málaga offers adequate conditions for the presence of fish larvae.


1997 ◽  
Vol 54 (7) ◽  
pp. 1504-1512 ◽  
Author(s):  
C M Mayer ◽  
D H Wahl

We examined prey preference, growth, and survival of small larval (8-10 mm total length (TL)), large larval (11-17 mm TL), and early juvenile (>18 mm TL) walleye (Stizostedion vitreum) in laboratory aquaria and field mesocosms using multiple prey assemblages that included cladoceran, copepod, and rotifer prey of varied sizes. Both prey taxa and size affected prey preference during the larval period. All sizes of walleye avoided rotifer and nauplii prey. Small and large larvae selected for intermediate-sized (0.4-0.9 mm) cladoceran prey and selected against large prey (>0.9 mm) of both taxa. Although neither capture efficiency nor handling time differed between prey taxa, larvae oriented more frequently towards cladoceran prey suggesting that they were more visible than copepods to these small fish. Larval walleye that were fed exclusively cladoceran prey survived better than fish that were fed other prey. Early juveniles selected primarily on the basis of prey size, choosing large copepods and cladocerans. Prey taxa did not affect early juvenile growth or survival. Prey taxa and prey size interacted with predator size to influence selectivity and its effect on growth and survival. Consequently, these factors must be considered in combination when examining the importance of foraging decisions in young fish.


1993 ◽  
Vol 50 (3) ◽  
pp. 465-471 ◽  
Author(s):  
Wim Hoogenboezem ◽  
Eddy H. R. R. Lammens ◽  
Peter J. MacGillavry ◽  
Ferdinand A. Sibbing

The hypothesis that the variability in prey-size selection of filter-feeding bream (Abramis brama) is related to sieve adjustment was tested by feeding bream of approximately 20 and 30 cm standard length with daphnids. The size-selective feeding observed in experiments was compared with predicted selectivity curves derived from the channel width of branchial sieves, total filtered volume, and the retention probability of prey in the reduced or unreduced channels. The relationship between mesh size and retention probability of Daphnia of known length was determined empirically in sieving experiments using commercial sieves. The results with 20-cm fish demonstrated that the variability in prey selection of bream can be explained by the adjustment of its filter in two distinct mesh sizes. The relationship between filter adjustment and zooplankton availability was not always clear. The retention ability of large bream (>30 cm) was in close accordance with the model prediction for filter-feeding with reduced channels.


1980 ◽  
Vol 58 (11) ◽  
pp. 2065-2070 ◽  
Author(s):  
R. J. Lamb ◽  
S. M. Smith

Certain life-history characteristics of Toxorhynchites brevipalpis and Tx. rutilus septentrionalis were compared in the laboratory with the aim of accounting for a more than twofold difference in the weight of their eggs. First- and second-instar larvae of Tx. rutilus were longer and third-instar larvae shorter than corresponding stages of Tx. brevipalpis. The sizes of the two species did not differ appreciably in the later stages. Toxorhynchites rutilus first-instar larvae consumed more prey but total prey consumption was much greater for Tx. brevipalpis due to differences in consumption during the fourth instar. Developmental times from egg to adult did not differ at 25 °C. Toxorhynchites brevipalpis produced twice as many eggs per day during the first 14 days of oviposition but, due to size differences, the weight of the eggs produced per day was equal for the two species. Female Tx. brevipalpis laid an average of 5.9 eggs per oviposition flight. A corresponding value for Tx. rutilus was not determined. Newly hatched Tx. brevipalpis larvae withstood starvation for a longer period of time than Tx. rutilus larvae. Larval Tx. rutilus captured and consumed larger prey.It is hypothesized that egg size and fecundity are adapted to prey size and heterogeneity in prey availability in the natural environments of the two species.


Author(s):  
Gary Totten

This chapter discusses how consumer culture affects the depiction and meaning of the natural world in the work of American realist writers. These writers illuminate the relationship between natural environments and the social expectations of consumer culture and reveal how such expectations transform natural space into what Henri Lefebvre terms “social space” implicated in the processes and power dynamics of production and consumption. The representation of nature as social space in realist works demonstrates the range of consequences such space holds for characters. Such space can both empower and oppress individuals, and rejecting or embracing it can deepen moral resolve, prompt a crisis of self, or result in one’s death. Characters’ attempts to escape social space and consumer culture also provide readers with new strategies for coping with their effects.


Quaternary ◽  
2021 ◽  
Vol 4 (1) ◽  
pp. 7
Author(s):  
Miki Ben-Dor ◽  
Ran Barkai

We hypothesize that megafauna extinctions throughout the Pleistocene, that led to a progressive decline in large prey availability, were a primary selecting agent in key evolutionary and cultural changes in human prehistory. The Pleistocene human past is characterized by a series of transformations that include the evolution of new physiological traits and the adoption, assimilation, and replacement of cultural and behavioral patterns. Some changes, such as brain expansion, use of fire, developments in stone-tool technologies, or the scale of resource intensification, were uncharacteristically progressive. We previously hypothesized that humans specialized in acquiring large prey because of their higher foraging efficiency, high biomass density, higher fat content, and the use of less complex tools for their acquisition. Here, we argue that the need to mitigate the additional energetic cost of acquiring progressively smaller prey may have been an ecological selecting agent in fundamental adaptive modes demonstrated in the Paleolithic archaeological record. We describe several potential associations between prey size decline and specific evolutionary and cultural changes that might have been driven by the need to adapt to increased energetic demands while hunting and processing smaller and smaller game.


2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 397-398
Author(s):  
Xiaoxia Dai ◽  
Kenneth Kalscheur ◽  
Pekka Huhtanen ◽  
Antonio Faciola

Abstract The effects of ruminal protozoa (RP) concentration on methane emissions from ruminants were evaluated in a meta-analysis using 67 publications reporting data from 85 in vivo experiments. Experiments included in the database reported methane emissions (g/kg DMI) and RP (log10 cells/mL) from the same group of animals. Quantitative data including diet chemical composition, ruminal fermentation, total tract digestibility, and milk production; and qualitative information including methane mitigation strategies, animal type, and methane measurement methods were also collected. The studies were conducted in dairy cows (51%), beef steers (32%) and small ruminants (32%). 70% of the studies reported a reduction in methane emissions. Supplemental lipids reduced methane emissions 95% of the time. The relationship between methane emissions and RP concentration was evaluated as a random coefficient model with the experiment as a random effect and weighted by the inverse pooled SEM squared, including the possibility of covariance between the slope and the intercept. A quadratic effect of RP concentration on methane emissions was detected: CH4= -28.8 + 12.2 × RP-0.64 × RP2. To detect potential interfering factors in the relationship, the influence of several qualitative and quantitative factors were separately tested. Acetate, butyrate, and isobutyrate molar proportions had positive relationships with methane emissions and influenced the relationship between RP concentration and methane emissions, where the presence of ruminal fermentation variables reduced the effects of RP concentration in methane emissions. Total tract digestibility of DM, OM, and CP had negative relationships while NDF digestibility had a positive relationship with methane emissions; however, they only changed the magnitude of intercept and slope of RP and RP2 for the relationship. For dairy cows, milk fat and protein concentrations had positive relationships and milk yield had a negative relationship with methane emissions and changed the magnitude of intercept and slope of RP and RP2 for the relationship.


The Condor ◽  
2021 ◽  
Vol 123 (1) ◽  
Author(s):  
Tasso C Cocoves ◽  
Mark I Cook ◽  
Jeffrey L Kline ◽  
Lori Oberhofer ◽  
Nathan J Dorn

Abstract As avian reproductive success is generally prey limited, identifying important prey types or sizes and understanding mechanisms governing prey availability are important objectives for avian conservation ecology. Irruptive White Ibis (Eudocimus albus) nesting at coastal colonies in the southern Everglades numbered over 100,000 nests in the 1930s. A century of drainage and altered hydrologic patterns reduced aquatic prey availability and eliminated large nesting events; nesting activity in recent decades has been typically less than 5% of historical peaks. Hydrologic restoration is expected to increase ibis nesting activity, but which prey types will support high nesting effort is less clear. In 2017 and 2018, we collected food boluses from White Ibis chicks at coastal colonies in Everglades National Park. We also monitored regional nesting activity from 1999 to 2018. In 2017, the region had 1,075 nests, typical of the past several decades; but in 2018, there were 30,420 nests, representing the highest recorded nesting activity in 87 yr. Prey composition varied between years; estuarine crabs dominated nestling boluses in 2017, while crayfish and fish were dominant prey in 2018. Crayfish, especially Procambarus alleni, were heavily exploited by ibis early in the 2018 breeding season, while fish were used more at the end. Crayfish abundances in wetlands near the colonies were higher prior to 2018, and more crayfish-producing short-hydroperiod wetlands remained available for ibis foraging in 2018. Our results support previous studies indicating that crayfish are important prey for breeding ibises and suggest that unprecedented, extensive flooding of seasonal wetlands promoted crayfish production and initiated the irruptive breeding in 2018. Our observations indicate that rehydration of the southern Everglades could restore ibis nesting activity at coastal colonies, but further investigations of hydrologic variation, crayfish production, and ibis foraging and nesting activity will be helpful to understand these dynamics and the importance of short-hydroperiod wetlands.


2016 ◽  
Vol 14 (3) ◽  
Author(s):  
Santiago A. Barbini ◽  
Luis O. Lucifora

ABSTRACT The eyespot skate, Atlantoraja cyclophora, is an endemic species from the southwestern Atlantic, occurring from Rio de Janeiro, Brazil, to northern Patagonia, Argentina. The feeding habits of this species, from off Uruguay and north Argentina, were evaluated using a multiple hypothesis modelling approach. In general, the diet was composed mainly of decapod crustaceans, followed by teleost fishes. Molluscs, mysidaceans, amphipods, isopods, lancelets and elasmobranchs were consumed in lower proportion. The consumption of shrimps drecreased with increasing body size of A. cyclophora. On the other hand, the consumption of teleosts increased with body size. Mature individuals preyed more heavily on crabs than immature individuals. Teleosts were consumed more in the south region (34º - 38ºS) and crabs in the north region (38º - 41ºS). Shrimps were eaten more in the warm season than in the cold season. Prey size increased with increasing body size of A. cyclophora , but large individuals also consumed small teleosts and crabs. Atlantoraja cyclophora has demersal-benthic feeding habits, shifts its diet with increasing body size and in response to seasonal and regional changes in prey availability and distribution.


2002 ◽  
Vol 32 (3) ◽  
pp. 499-499 ◽  
Author(s):  
Rosseval Galdino LEITE ◽  
Carlos A.R.M. ARAUJO-LIMA

Information on larval fish feeding is essential for understanding their trophic relations, including the management in conditions totally or partially controlled by humans. An experiment was designed to evaluate the larval diets of three commercially important species. Four varzea-lakes and the adjacent river were sampled with bongo and hand nets from January 1993 to November 1995. Larval diets were evaluated by length-classes and capture sites, and were tested by two factor ANOVA. The larvae were feeding in all habitats, except in the flooded forests. The three species had different diets, which varied with their length and lake. The rotifers were the main initial food item of the three species, replaced by fish larvae in Brycon cephalus, cladocerans in Triportheus elongatus and detritus in Semaprochilodus insignis. The increase of the ingestion limit, as the larvae grew, was higher than the increase in the consumed prey size for the three species.


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