An external tag for fish: tagging effects in different fish size classes and its influence on growth performance and hematology of Lophiosilurus alexandri (Siluriformes: Pseudopimelodidae)

Analysis of stomach contents for Dasyatis chrysonota revealed that diet varied with size and habitat. The diet of all size classes in the surf zone was comprised primarily of Callianassa spp., Donax spp. and unidentified polychaete species. The medium and large size classes fed primarily on Donax spp., whereas the very large size class fed mainly on Callianassa spp. Polychaetes were of secondary importance as prey for the medium size class. The diet of D. chrysonota in the nearshore zone consisted mainly of Balanoglossus capensis and Callianassa spp. Balanoglossus capensis decreased from an index of relative importance (IRI) of 75.3% for the medium size class to 59.9% for the very large size class, whereas Callianassa spp. increased from 22.8% to 39.4% between the medium and the very large size classes. The offshore zone was the only area in which small size class D. chrysonota were caught. The diet of these small D. chrysonota was primarily polychaetes and amphipods. Polychaetes increased in importance in the medium size class, but declined in each successively larger size class. Conversely, Pterygosquilla armata capensis became the single most important prey item for the very large size class, comprising an IRI of 50.9%. The behaviour pattern used by D. chrysonota to locate and extract prey is described.

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The Effect of the Decorator Crab Notomithrax Minor on Cultivated Greenshell Mussel Spat (Perna Canaliculus) Survival, Growth, and Byssal Characteristics

10.26686/wgtn.16992331 ◽

2021 ◽

Author(s):

◽

Irene Van de Ven

Keyword(s):

Retention Rate ◽

Experimental Testing ◽

Preliminary Evidence ◽

Size Classes ◽

Perna Canaliculus ◽

Large Size ◽

Field Investigations ◽

Attachment Strength ◽

Decorator Crab ◽

Financial Losses

<p>The decorator crab Notomithrax minor is common on Greenshell mussel (Perna canaliculus) farms in the Marlborough Sounds, New Zealand. Individuals in the Greenshell mussel industry have suggested that the presence of N. minor, found on mussel lines, is related to substantial losses of Greenshell mussel spat. Laboratory and field investigations were used to assess the effect of N. minor presence on the retention and productivity of Greenshell musselTM spat. Specific consideration was given to predation pressure and induced anti-predator defenses, both of which can cause financial losses to mussel farmers. High (12 crabs/cage-1) and low (3 crabs/cage-1) densities of large (males: >20mm, females: >15mm TCW) and medium (males: 15-20mm, females: 10-15mm TCW) decorator crabs were placed in cages on commercial Greenshell mussel farm droppers at two sites in the Pelorus Sound. The byssal characteristics, spat retention rate and spat shell length were assessed at 8 and 11 weeks after trial initiation. Greenshell mussel density on the experimental droppers decreased significantly when medium and high densities of the decorator crabs (N. minor) were introduced. N. minor presence induced the remaining Greenshell mussel spat to produce more and thicker byssus threads which consequently lead to increased mussel attachment. The decrease in retention rate and the increase in mussel attachment strength were more pronounced in small recently seeded spat. Laboratory experiments to assess the consumption rate of small (≤5mm) Greenshell mussel spat by decorator crabs showed that mussel consumption by N. minor peaked at 56.43 (± 13.02 (95% C.I.)) crab-1 hr-1, however the rate of consumption decreased significantly over the duration of the three day trial. N. minor prey size preference was also assessed using Laboratory trials; crabs were offered 4 size classes of mussels (small (<5 mm), small-medium (5-10 mm), medium-large (10-15 mm), large (>15 mm) simultaneously. Female crabs consumed more mussels in the <5 mm and 5-10 mm size classes than in the two larger mussel size classes (10-15 mm and >15 mm), whereas the male crabs showed a numerical preference for mussel spat in the small-medium and medium-large size classes. This study provides preliminary evidence that the decorator crab N. minor is a previously overlooked and under-estimated threat to the Greenshell Mussel industry in the Marlborough Sounds that deserves closer scrutiny and experimental testing.</p>

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Size dominance regulates tree spacing more than competition within height classes in tropical Cameroon

Journal of Tropical Ecology ◽

10.1017/s0266467410000453 ◽

2010 ◽

Vol 27 (1) ◽

pp. 93-102 ◽

Cited By ~ 19

Author(s):

Stephan Getzin ◽

Martin Worbes ◽

Thorsten Wiegand ◽

Kerstin Wiegand

Keyword(s):

Plant Growth ◽

Secondary Forest ◽

Random Pattern ◽

Minor Importance ◽

Competitive Effects ◽

Size Classes ◽

Large Size ◽

Weak Evidence ◽

Large Size Class ◽

And Performance

Abstract:Does competition prevail in large size classes of trees in tropical forests? This question is fundamental to our understanding of the demography and dynamics occurring in rain forests. We investigated this question based on an undisturbed late-secondary forest on a 1-ha plot in central Cameroon. Trees were stem-mapped and classified into three size classes: understorey, midstorey and overstorey. The diameter at breast height and yearly biomass increment were determined as measures of plant growth and performance. Spatial statistics such as pair- and mark-correlation functions were used to detect scale-dependent patterns that could be caused by competition within and between the three size classes. The results revealed a random pattern and spatially uncorrelated measures of plant growth of overstorey trees. This suggests that competitive effects are of minor importance in the large size class of overstorey trees. Likewise, only weak evidence for competition between trees was found within the two lower size classes. However, negative distance correlations were found between the different size classes. We suggest that competition within height classes was relatively low due to the diversity of species with their variable niche differentiations and phenotypic plasticity that may compensate for competitive effects.

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Effect of Dietary Protein Levels on Growth Performance, Hematological Parameters and Digestive Enzymes in Juveniles of Brycon amazonicus (Spix & Agassiz, 1829)

10.20944/preprints202112.0131.v1 ◽

2021 ◽

Author(s):

Anny Cristina V. Leite ◽

Jackson Pantoja-Lima ◽

Renan R. Paulino ◽

Márcia Regina Fragoso M. Bussons ◽

Rodrigo Y. Gimbo ◽

...

Keyword(s):

Growth Performance ◽

Digestive Enzymes ◽

Crude Protein ◽

Retention Rate ◽

Hematological Parameters ◽

Matter Content ◽

Whole Body ◽

Dry Matter Content ◽

Feed Conversion ◽

Protein Levels

A 52-day experiment was conducted to determine the crude protein (CP) requirements of juvenile matrinxã Brycon amazonicus, and to evaluate their resulting growth performance, hematological parameters and enzymatic activities. Sixty fish (29.03g ± 1.16g) were distributed in 12 tanks (310 L) with a completely randomized design, and maintained at four dietary crude protein levels (270, 320, 350, 390 g.kg-1) for 52 days. The results revealed that the fish fed diet 390 g.kg-1 CP had the best final weight, weight gain, feed conversion ratio, specific growth rate, protein efficiency ratio and lipid retention rate. The same could be stated for hematocrit, number of circulating erythrocytes, triglycerides and total proteins of the hematological profile (p&lt;0.05). In the whole body composition, dry matter content was lower in the fish fed 390 g.kg-1 CP, while lipid content was higher in the fish fed 350-390 g.kg-1 CP (p&lt;0.05). No differences were observed in CP and ash (p&gt;0.05), or in the activities of digestive enzymes (p&gt;0.05). In short, our findings suggest benefits of the 390 g.kg-1 CP feed for being the most adequate for this species’ juvenile stage.

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The Effect of the Decorator Crab Notomithrax Minor on Cultivated Greenshell Mussel Spat (Perna Canaliculus) Survival, Growth, and Byssal Characteristics

10.26686/wgtn.16992331.v1 ◽

2021 ◽

Author(s):

◽

Irene Van de Ven

Keyword(s):

Retention Rate ◽

Experimental Testing ◽

Preliminary Evidence ◽

Size Classes ◽

Perna Canaliculus ◽

Large Size ◽

Field Investigations ◽

Attachment Strength ◽

Decorator Crab ◽

Financial Losses

<p>The decorator crab Notomithrax minor is common on Greenshell mussel (Perna canaliculus) farms in the Marlborough Sounds, New Zealand. Individuals in the Greenshell mussel industry have suggested that the presence of N. minor, found on mussel lines, is related to substantial losses of Greenshell mussel spat. Laboratory and field investigations were used to assess the effect of N. minor presence on the retention and productivity of Greenshell musselTM spat. Specific consideration was given to predation pressure and induced anti-predator defenses, both of which can cause financial losses to mussel farmers. High (12 crabs/cage-1) and low (3 crabs/cage-1) densities of large (males: >20mm, females: >15mm TCW) and medium (males: 15-20mm, females: 10-15mm TCW) decorator crabs were placed in cages on commercial Greenshell mussel farm droppers at two sites in the Pelorus Sound. The byssal characteristics, spat retention rate and spat shell length were assessed at 8 and 11 weeks after trial initiation. Greenshell mussel density on the experimental droppers decreased significantly when medium and high densities of the decorator crabs (N. minor) were introduced. N. minor presence induced the remaining Greenshell mussel spat to produce more and thicker byssus threads which consequently lead to increased mussel attachment. The decrease in retention rate and the increase in mussel attachment strength were more pronounced in small recently seeded spat. Laboratory experiments to assess the consumption rate of small (≤5mm) Greenshell mussel spat by decorator crabs showed that mussel consumption by N. minor peaked at 56.43 (± 13.02 (95% C.I.)) crab-1 hr-1, however the rate of consumption decreased significantly over the duration of the three day trial. N. minor prey size preference was also assessed using Laboratory trials; crabs were offered 4 size classes of mussels (small (<5 mm), small-medium (5-10 mm), medium-large (10-15 mm), large (>15 mm) simultaneously. Female crabs consumed more mussels in the <5 mm and 5-10 mm size classes than in the two larger mussel size classes (10-15 mm and >15 mm), whereas the male crabs showed a numerical preference for mussel spat in the small-medium and medium-large size classes. This study provides preliminary evidence that the decorator crab N. minor is a previously overlooked and under-estimated threat to the Greenshell Mussel industry in the Marlborough Sounds that deserves closer scrutiny and experimental testing.</p>

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Triploidy induction in tambaqui (Colossoma macropomum) using thermal shock: fertilization, survival and growth performance from early larval to the juvenile stage

Journal of Applied Aquaculture ◽

10.1080/10454438.2021.1914800 ◽

2021 ◽

pp. 1-16

Author(s):

Gabriela Silva Júnior ◽

Carlos E. Copatti ◽

Lucas Costa ◽

Gustavo Souza ◽

Hugo C. Bonfá ◽

...

Keyword(s):

Growth Performance ◽

Thermal Shock ◽

Juvenile Stage ◽

Colossoma Macropomum ◽

Triploidy Induction ◽

Survival And Growth

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Effect of Acetic Acid and Sodium Bicarbonate Supplemented to Drinking Water on Water Quality, Growth Performance, Organ Weights, Cecal Traits and Hematological Parameters of Young Broilers

Animals ◽

10.3390/ani11071865 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1865

Author(s):

Yordan Martínez ◽

Cristopher Isaac Almendares ◽

Cristhian José Hernández ◽

Mavir Carolina Avellaneda ◽

Ana Melissa Urquía ◽

...

Keyword(s):

Water Quality ◽

Drinking Water ◽

Acetic Acid ◽

Sodium Bicarbonate ◽

Growth Performance ◽

Hematological Parameters ◽

Relative Weight ◽

Biological Response ◽

Blood Parameters ◽

Organ Weights

To evaluate the effect of acetic acid and sodium bicarbonate supplemented to drinking water on water quality, growth performance, relative organ weights, cecal traits and hematological parameters of broilers, a total of 456 one-day-old Cobb MV × Cobb 500 FF mixed broilers were randomly placed in three experimental treatments, with four replicates per treatment and 38 birds per replicate, for 10 days. The treatments consisted of the use of acetic acid (0.4%; T1) as acidifier, an apparently neutral pH (T2) and sodium bicarbonate (1%; T3) as alkalizer of the drinking water. T3 showed the highest values (p < 0.05) for total dissolved solids, electrical conductivity, salinity and pH. T1 and T2 showed the same productive response (p > 0.05); however, T3 decreased (p < 0.05) body weight, feed intake and the relative weight of the pancreas and immune organs and increased (p < 0.05) water intake, mortality and relative weight of the heart and liver. Likewise, T3 increased (p < 0.05) the cecal pH, although without changes for the cecal lactic cecal bacteria count and blood parameters (p > 0.05). The acid pH of the drinking water had no effect on the biological response of broilers compared to T2; however, the T3 provoked high mortality, ascites, low productivity and abnormal growth of some organs.

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