Stomach contents of immature lobsters (Homarus americanus) from Placentia Bay, Newfoundland

1982 ◽  
Vol 60 (3) ◽  
pp. 337-347 ◽  
Author(s):  
J. A. Carter ◽  
D. H. Steele
Keyword(s):  
Sea Urchins ◽  
Stomach Contents ◽  
Late Summer ◽  
Homarus Americanus ◽  
Stomach Fullness ◽  
Natural Diet ◽  
Selection Indices ◽  
Selection For ◽  
Placentia Bay ◽  
High Selection

Stomachs of immature lobsters (Homarus americanus) from Placentia Bay, Newfoundland, were examined to determine natural diet. The most frequently occurring prey were sea urchins, mussels, rock crabs, polynoid and nereid polychaetes, and brittlestars. There was high incidence of lobster exuviae during the moulting period in late summer. Rock crabs, brittlestars, and mussels were dominant (in terms of relative volumes of hard parts in each stomach) more often than other food items. Sea urchins, periwinkles, chitons, rock crabs, and polynoids were consumed more frequently in late summer compared with other seasons. Stomach contents constituted approximately 1% of the wet weight of individual lobsters. There were no significant seasonal differences in stomach fullness during the period June to November.The residencies of natural prey hard parts in immature lobster stomachs were estimated. Some items remained in stomachs for up to 180 days. Measures of stomach fullness of lobsters 3 days after ad libitum feeding on rock crabs, mussels, and sea urchins were similar. Linear selection indices indicated relatively high selection by immature lobsters for hard parts of rock crabs and mussels and positive selection for nereids, polynoids, and brittlestars. Immature lobsters showed negative selection for hard parts of sea urchins, starfish, and periwinkles.

Seaweeds, Sea Urchins, and Lobsters: A Reappraisal

1985 ◽  
Vol 42 (12) ◽  
pp. 2061-2072 ◽  
Author(s):  
Robert J. Miller
Keyword(s):  
Sea Urchin ◽  
Sea Urchins ◽  
Stomach Contents ◽  
Homarus Americanus ◽  
Strongylocentrotus Droebachiensis ◽  
Sea Otter ◽  
Feeding Rates ◽  
Growth And Survival ◽  
Definition Of ◽  
Urchin Grazing

A popular hypothesis, that on the south coast of Nova Scotia the green sea urchin (Strongylocentrotus droebachiensis) has been released from control by predators, is critically reviewed. Predator control is given the functional definition of limiting sea urchin grazing sufficient to permit abundant growth of seaweed. Of the predators identified, the American lobster (Homarus americanus) is the least likely to have been important in sea urchin control in recent decades. Feeding rates, stomach contents, and field biomass are available for this species. A smaller amount of data available for the rock crab (Cancer irroratus) and benthic feeding fish points to the conclusion that they likewise cannot control urchin populations. Among other temperate sea urchin species the case is strongest for sea otter control of Strongylocentrotus sp. in some areas of the west coast of North America. The formation of sea urchin grazing fronts, a usual step in the destruction of seaweed beds, has been explained as a behavioral response to predators. This may in fact be merely a response to the location of food. Evidence for suspected enhancement of lobster production by seaweeds is equivocal, and comparative field data collected in and out of seaweed beds (e.g. lobster abundance, food, growth, and survival) have not been published.

Feeding by Hatchery-Reared and Wild Atlantic Salmon (Salmo salar) Parr in Streams

1979 ◽  
Vol 36 (11) ◽  
pp. 1408-1412 ◽  
Author(s):  
A. J. Sosiak ◽  
R. G. Randall ◽  
J. A. McKenzie
Keyword(s):  
Atlantic Salmon ◽  
Key Words ◽  
Salmo Salar ◽  
Food Selection ◽  
Stomach Contents ◽  
Stomach Fullness ◽  
Size Dependent ◽  
Atlantic Salmon Salmo Salar ◽  
Feeding Experience ◽  
Salmon Parr

Hatchery-reared Atlantic salmon (Salmo salar) parr were captured 1–3 mo after release in streams, along with wild parr from the same streams. Identification of their stomach contents showed total number of organisms and number of taxa per stomach were greater and there was a higher index of stomach fullness in wild than in hatchery parr resident ≤ 2 mo in a stream. Wild parr consumed more Brachycentridae, Hydroptilidae, Diptera, and Plecoptera than did hatchery parr, but sometimes less Odontoceridae and Heptageniidae. These differences may have arisen from size-dependent food selection, the effects of feeding experience, or possible microhabitat differences between wild and hatchery parr. Key words: salmon parr, hatchery-reared, wild, feeding

scholarly journals Contrasting recruitment seasonality of sea urchin species in Gran Canaria, Canary Islands (eastern Atlantic)

2014 ◽  
Vol 15 (3) ◽  
pp. 475 ◽  
Author(s):  
S. GARCIA-SANZ ◽  
P. G. NAVARRO ◽  
F. TUYA
Keyword(s):  
Community Structure ◽  
Seasonal Variation ◽  
Sea Urchin ◽  
Sea Urchins ◽  
Late Summer ◽  
Paracentrotus Lividus ◽  
Abundant Species ◽  
Late Winter ◽  
Gran Canaria ◽  
Arbacia Lixula

Despite sea-urchins can play an important role affecting the community structure of subtidal bottoms, factors controlling the dynamics of sea-urchin populations are still poorly understood. We assessed the seasonal variation in recruitment of three sea-urchin species (Diadema africanum, Paracentrotus lividus and Arbacia lixula) at Gran Canaria Island (eastern Atlantic) via monthly deployment of artificial collectors throughout an entire annual cycle on each of four adjacent habitat patches (seagrasses, sandy patches, ‘urchin-grazed’ barrens and macroalgal-dominated beds) within a shallow coastal landscape. Paracentrotus lividus and A. lixula had exclusively one main recruitment peak in late winter-spring. Diadema africanum recruitment was also seasonal, but recruits appeared in late summer-autumn, particularly on ‘urchin-grazed’ barrens with large abundances of adult conspecifics. In conclusion, this study has demonstrated non-overlapping seasonal recruitment patterns of the less abundant species (P. lividus and A. lixula) with the most conspicuous species (D. africanum) in the study area.

Ontogenetic shifts in natural diet, chelae, and mandible of an omnivorous freshwater crab (Aegla uruguayana): linking morphology and function

2021 ◽  
Author(s):  
Maria Florencia Viozzi ◽  
Juan Manuel Cabrera ◽  
Federico Giri ◽  
Debora de Azevedo Carvalho ◽  
Verónica Williner
Keyword(s):  
Morphological Changes ◽  
Feeding Strategy ◽  
Stomach Contents ◽  
Trophic Niche ◽  
Composition Analysis ◽  
Diet Change ◽  
Geometric Morphometric ◽  
Natural Diet ◽  
Plant Remains ◽  
And Function

We analyze whether ontogenetic diet change in Aegla uruguayana (Schmitt, 1942) is related to the morphological changes in chelae and mandibles. We use a combination of scanning electron microscope observation (SEM), dietary composition analysis (stomach observation, trophic niche amplitude, trophic overlap, and feeding strategy), and geometric morphometric tools (discriminant analysis and two-block partial least squares analysis). The two structures analyzed by SEM show differences between juvenile and adult specimens, both in their cuticle and morphology specializations. In juveniles, the absence of the lobular tooth is the notable feature. However, in adult sizes it is marked development. Both groups have simple setae with infracuticular articulation and denticles with different arrangements between groups. In the incisive mandible process, the teeth and spines present sharper points in juveniles and considerable wear in adults. Aegla uruguayana presented two trophic strategies: a profile of more predatory traits when younger and mostly detritivorous when adults. The analysis of geometric morphometry substantiates the patterns observed in SEM and stomach contents analysis. The morphology of smaller specimens is associated with the consumption of animal items (ephemeropterans larvae and cladocerans), while in those of larger sizes; it is related to the consumption of plant remains.

Selection for improved carcass composition in Suffolk Sheep : Interim Results

1990 ◽  
Vol 1990 ◽  
pp. 9-9
Author(s):  
G Simm ◽  
W S Dingwall ◽  
S V Murphy ◽  
J FitzSimons ◽  
W R Brown
Keyword(s):  
Cost Effective ◽  
Carcass Composition ◽  
Short Term ◽  
Genetic Potential ◽  
Selection Indices ◽  
Selection For ◽  
Breed Selection ◽  
Terminal Sire ◽  
Suffolk Sheep

It is likely that returns from lamb production in future will depend, much more than at present, on producing leaner carcasses. There are several short-term changes in management which could produce leaner carcasses. However, In the longer term genetic Improvement, particularly by within-breed selection In terminal sire breeds, is likely to provide permanent, cumulative and cost-effective benefits In carcass composition. In the early 1980s a research project was started at the Edinburgh School of Agriculture, using Suffolk sheep, to examine the genetic potential for Improving carcass composition In terminal sires. The work commenced with an evaluation of techniques for in vivo measurement of carcass composition (Simm, 1987) and derivation of selection indices to incorporate In vivo measurements (Simm and Dingwall, 1989). Since 1985 In vivo measurement and Index selection have been practised In the experimental flock, which now numbers about 220 ewes. This paper reports the interim results of selection.

Heritability of frost tolerance in white clover (Trifolium repens)

1990 ◽  
Vol 114 (2) ◽  
pp. 151-155 ◽  
Author(s):  
J. R. Caradus ◽  
A. C. Mackay ◽  
J. Van Den Bosch ◽  
S. Wewala ◽  
D. H. Greer
Keyword(s):  
White Clover ◽  
Trifolium Repens ◽  
Size Effects ◽  
Leaf Size ◽  
Frost Damage ◽  
Frost Tolerance ◽  
Method Of Calculation ◽  
Selection For ◽  
Heritability Estimates ◽  
High Selection

SUMMARYWhite clover genotypes selected for frost tolerance and susceptibility were pair-crossed in various combinations with unselected genotypes of Grasslands Huia. Progeny lines and parent genotypes were artificially frosted at −8°C and scored for percentage of leaves damaged. Progeny from crosses between frost-tolerant genotypes were less damaged by frost than progeny from crosses involving either susceptible genotypes or unselected Grasslands Huia genotypes. Heritability estimates for frost tolerance or susceptibility were high, ranging from 0·75 to 0·93, depending on method of calculation. Removal of leaf-size effects from scores of frost damage reduced heritability estimates to 0·54–0·73. It was concluded that, because heritability for frost tolerance was high, selection for this character and incorporation of frost tolerance into agronomically suitable but frost-sensitive cultivars by breeding would be successful.

scholarly journals Characteristics of survivors: growth and nutritional condition of early stages of the hake species Merluccius paradoxus and M. capensis in the southern Benguela ecosystem

2012 ◽  
Vol 69 (4) ◽  
pp. 553-562 ◽  
Author(s):  
Britta Grote ◽  
Werner Ekau ◽  
Erling K. Stenevik ◽  
Catriona Clemmesen ◽  
Hans M. Verheye ◽  
...  
Keyword(s):  
Selection Pressure ◽  
Larval Mortality ◽  
Larval Growth ◽  
Threshold Level ◽  
Nutritional Condition ◽  
Complex Relationship ◽  
Early Stages ◽  
Benguela Upwelling ◽  
Selection For ◽  
High Selection

Abstract Grote, B., Ekau, W., Stenevik, E. K., Clemmesen, C., Verheye, H. M., Lipinski, M. R., and Hagen, W. 2012. Characteristics of survivors: growth and nutritional condition of early stages of the hake species Merluccius paradoxus and M. capensis in the southern Benguela ecosystem. – ICES Journal of Marine Science, 69: 553–562. Larval mortality in marine fish is strongly linked to characteristic traits such as growth and condition, but the variability in these traits is poorly understood. We tried to identify the variability in growth in relation to conditions leading to greater survival chances for early stages of Cape hake, Merluccius paradoxus and M. capensis, in the Benguela upwelling ecosystem. During two cruises in 2007 and one cruise in 2008, hake larvae and juveniles were caught. Otolith microstructures revealed a larval age ranging from 2 to 29 days post-hatching (dph), whereas juvenile age was 67–152 dph. RNA:DNA ratios, used to evaluate nutritional condition, were above the relevant threshold level for growth. No strong coupling between growth and condition was detected, indicating a complex relationship between these factors in the southern Benguela ecosystem. Merluccius paradoxus juveniles caught in 2007 (the surviving larvae of 2006) had significantly higher larval growth rates than larvae hatched in 2007 and 2008, possibly indicating selection for fast growth in 2006. High selection pressure on growth could be linked to predation avoidance, including cannibalism.

Dietary Intake and Nutritional Characteristics in Wild American Lobsters (Homarus americanus)

1979 ◽  
Vol 36 (8) ◽  
pp. 965-969 ◽  
Author(s):  
D. F. Leavitt ◽  
R. C. Bayer ◽  
M. L. Gallagher ◽  
J. H. Rittenburg
Keyword(s):  
Amino Acid ◽  
Essential Amino Acid ◽  
Crude Protein ◽  
Stomach Contents ◽  
Homarus Americanus ◽  
Molt Cycle ◽  
Nutritional Characteristics ◽  
Gross Energy ◽  
Mineral Constituent ◽  
The Relationship

Nutrient and essential amino acid analyses of the stomach contents of wild adult American lobsters (Homarus americanus) collected from offshore and inshore populations indicated lobsters consumed varying nutrient levels according to their stage of molt. For example, soft-shell lobsters ate a higher level of mineral constituent. The location of the animal had no effect on the level of nutrient intake. The essential amino acid composition of the protein in the stomach remained the same throughout the molt cycle, but indicated a change in protein source with the location of the animal. The relationship between crude protein and gross energy was constant suggesting its importance in the nutrition of the lobster. Based on this study, we recommend a basal level of nutrient constituents for ration formulation. Key words: American lobster, natural intake, dietary formulation

Preparation and Characterization of Molecular Imprinted Polymers of Tetracycline Antibiotics by Mixed-Templates

2011 ◽  
Vol 128-129 ◽  
pp. 407-410
Author(s):  
Guo Li Gong ◽  
Lin Jia ◽  
Hui Li ◽  
Xiang Jun Qi
Keyword(s):  
Functional Monomer ◽  
Molecular Imprinted Polymers ◽  
Tetracycline Antibiotics ◽  
Imprinted Polymers ◽  
Extraction And Purification ◽  
Bonding Property ◽  
Cross Linker ◽  
Selection For ◽  
High Selection

Molecular imprinted polymers (MIPs) were synthesized in certain conditions in the experiment when tetracycline antibiotics (TCs), including Oxytetracycline, Chlortetracycline and Tetracycline were used as templates, methacrylic acid as functional monomer, and ethylene glycol dimethacrylate as cross-linker. Oxytetracycline and Chlortetracycline (1:1) were chosen as mixed-templates when the bonding property of the polymer was studied. The results showed that the mixed-templates MIPs had high selection for tetracycline, and were expected to be used as separation materials for the extraction and purification of TCs in animal food.

Variability in the Diet of Ringed Seals, Phoca hispida, in Alaska

1980 ◽  
Vol 37 (12) ◽  
pp. 2254-2261 ◽  
Author(s):  
Lloyd F. Lowry ◽  
Kathryn J. Frost ◽  
John J. Burns
Keyword(s):  
Stomach Contents ◽  
Late Summer ◽  
Beaufort Sea ◽  
Boundary Region ◽  
Early Summer ◽  
Phoca Hispida ◽  
Arctic Cod ◽  
Ringed Seals ◽  
Saffron Cod ◽  
Crangon Septemspinosa

Analysis of stomach contents of ringed seals (Phoca hispida) collected at eight locations along the Alaskan coast showed significant seasonal and regional differences in diet. During the spring–summer period saffron cod (Eleginus gracilis) was the most important food item in the nearshore zone of the northeastern Bering and southeastern Chukchi Seas. In that period shrimps (Pandalus spp., Eualus spp., Lebbeus polaris, and Crangon septemspinosa) were the major food in the northcentral Bering Sea, hyperiid amphipods (Parathemisto libellula) in the central Beaufort Sea and euphausiids (Thysanoessa spp.) in the boundary region (Barrow area) between the Chukchi and Beaufort seas. During late summer–early autumn hyperiid amphipods were important foods in the central Beaufort and the southeastern Chukchi. The autumn diet of seals in Norton Sound included mainly saffron cod During winter–early spring Arctic cod (Boreogadus saida) predominated the diet at all localities. During spring and early summer in the northeastern Bering and southeastern Chukchi seas the amount of saffron cod consumed was directly correlated with age. In the Beaufort Sea during autumn and winter Arctic cod were eaten in similar amounts by all age-classes. An analysis of the energy value and quantities of prey consumed indicates that prey species that occur in concentrations (Arctic and saffron cods, hyperiid amphipods, euphausiids and some shrimps) are of particular importance in the annual nutrition of ringed seals. These seals may be food limited in areas and during times when these kinds of prey are not available.Key words: food habits, Phoca hispida, ringed seals, Arctic cod, saffron cod, crustaceans, Alaska

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