scholarly journals FEEDING AND REPRODUCTIVE ACTIVITY OF THE COPEPODS Drepanopus forcipatus AND Calanus australis DURING LATE SUMMER ON THE SOUTHERN PATAGONIAN SHELF (ARGENTINA, 47°-55°S)

2014 ◽  
Vol 62 (4) ◽  
pp. 295-314 ◽  
Author(s):  
Julieta Carolina Antacli ◽  
Marina E. Sabatini ◽  
Ricardo I. Silva ◽  
Daniel R. Hernández ◽  
Andrés J. Jaureguizar ◽  
...  
Keyword(s):  
Diet Composition ◽  
Feeding Activity ◽  
Food Pellet ◽  
Late Summer ◽  
Reproductive Activity ◽  
Seasonal Temperature ◽  
Patagonian Shelf ◽  
Adult Females ◽  
Female Reproductive Status ◽  
Potential Food

Drepanopus forcipatus and Calanus australis are key planktonic copepods on the southern Patagonian shelf. Their feeding and reproductive patterns and population status were investigated during late summer, when environmental conditions may be critical. The presence of food in the gut and food-pellet length were recorded in adult females and the most abundant copepodite stages. Diet composition was also studied in adult females. Female reproductive status was evaluated by gonad staging. Despite generally low feeding conditions and decreasing seasonal temperature, both copepods fed to some degree. The most numerous copepodites and adult females of both species showed similarly low feeding activity. About half of the adult females of the two species and C5s of C. australis contained food in their guts, but the proportion of fed C4-females of D. forcipatus was much lower. All copepods were generally feeding at low or intermediate levels. Gonad stage distribution and population structure showed low but still ongoing reproduction in both species. Gut content findings suggest a preference for smaller nanoplanktonic particles, especially dinoflagellates by D. forcipatus, and for autotrophic prey, particularly large diatoms by C. australis. The feeding and reproduction patterns of the two copepods were likely influenced by the distributions of potential food resources and temperature.

scholarly journals Actividad reproductiva y dieta de Hemidactylus frenatus (Sauria: Gekkonidae) en el norte de Colombia

2017 ◽  
Vol 57 (36) ◽  
pp. 459
Author(s):  
Jorge A. Díaz-Pérez ◽  
Alcides C. Sampedro-Marín ◽  
Martha P. Ramírez-Pinilla
Keyword(s):  
Diet Composition ◽  
Sampling Period ◽  
Reproductive Activity ◽  
Climatic Conditions ◽  
Relative Importance ◽  
Adult Males ◽  
Adult Females ◽  
Ecological Aspects ◽  
Environmental Availability ◽  
Hemidactylus Frenatus

Despite its success as an invasive species, little is known about the ecological aspects of the gekkonid lizard Hemidactylus frenatus in Colombia. In the present study the size at maturity, sexual dimorphism, reproductive activity, and diet composition of a population of this species in an urban locality of Northern Colombia were determined. We conducted eleven samplings from September 2011 to August 2012 in buildings of the municipality of Sincelejo. A total of 264 specimens H. frenatus were captured, 112 were adult females, 133 adult males and 19 juveniles. Males reach sexual maturity at a smaller size (snout-vent length) than females (males: 35.7 mm; females: 42.7 mm), also they are larger and have proportionally larger heads and mouths than females. Males were reproductive throughout the year; although testicular volume varied significantly between samples, this variation was not associated with body size and precipitation in the study area. Reproductive adult females were found during all the sampling period. Females have an invariable clutch size of two eggs and we found no differences in the diameter and weight of eggs in each oviduct. The diet of H. frenatus is varied, with Diptera, Hemiptera and Formicidae being the prey types with the greatest relative importance values. Individuals of both sexes consume a similar volume and number of prey. Thus, the studied population of H. frenatus has continuous reproductive activity and a generalist-opportunistic feeding behavior. The climatic conditions of the study area, environmental availability of prey and intrinsic features of this species appear to be responsible for their abundance and colonizing success in this and other localities.

Variations in courtship activity among male blue grouse: do some males breed more than others?

1993 ◽  
Vol 71 (6) ◽  
pp. 1079-1083
Author(s):  
David P. Hervieux ◽  
Fred C. Zwickel ◽  
Richard A. Lewis
Keyword(s):  
Late Summer ◽  
Reproductive Activity ◽  
Adult Males ◽  
Primary Feather ◽  
Adult Females ◽  
Dendragapus Obscurus ◽  
Courtship Activity ◽  
Wear Index

We developed a primary feather wear index (WI) for blue grouse (Dendragapus obscurus) to examine variations in courtship activity among males. Three percent of 276 yearling males, and less than 1% of 144 yearling and adult females examined throughout spring and summer showed evidence of such wear. Among 630 adult males, 48% exhibited "courtship wear." Mean courtship wear among males 2 years old and older increased steadily throughout the spring and summer, generally paralleling what would be predicted from cumulative reproductive activity. However, there was much variation among males, ranging from no wear to heavy wear, even by late summer. These data are consistent with earlier suggestions that breeding may be skewed among male blue grouse, as in lek-breeding tetraonines. Limited samples indicate that primary feather wear was not related to the age of males (more than 1 year old) or their occupancy of persistent or transient territorial sites.

scholarly journals Feeding activity and diet composition of round goby (Neogobius melanostomus, Pallas 1814) in the coastal waters of SE Baltic Sea

2015 ◽  
Vol 44 (4) ◽  
Author(s):  
Artūras Skabeikis ◽  
Jūratė Lesutienė
Keyword(s):  
Baltic Sea ◽  
Coastal Waters ◽  
Diet Composition ◽  
Feeding Activity ◽  
Macoma Balthica ◽  
Round Goby ◽  
Benthic Fauna ◽  
Neogobius Melanostomus ◽  
The Body ◽  
Gut Contents

AbstractFeeding activity and diet composition of round goby were investigated in the south-eastern Baltic Sea, the Lithuanian coastal waters during May-October 2012 in order to determine main feeding objects and seasonal periods when native fauna could be most affected by predation of this highly invasive species. In total, prey represented by 18 taxa was found in the gut contents of dissected fish. Feeding activity of round goby varied depending on the body size, sex and stage of the reproduction period. The gut contents of < 50 mm specimens were dominated by zooplanktonic and meiobenthic organisms, whereas larger individuals (50–99 mm) shifted to amphipods and mollusks. Individuals of the intermediate 100-200 mm length had a variable diet, changing depending on the season; in spring they mostly preyed on Macoma balthica, in summer − on polychaetes, while in autumn the contribution of Mytilus trossulus and fish considerably increased in their diet. Diet composition of individuals ≥ 200 mm was relatively constant in the course of the study with substantial preference to M. balthica. These findings imply that benthic fauna, particularly a newly settled generation of epibenthic mollusks in autumn is under strong predatory pressure of the round goby.

scholarly journals Diet Composition and Seasonal Fluctuations in the Feeding Habit of Snow Barbel (Schizothorax plagiostomus) in River Indus, Pakistan

2018 ◽  
Vol 46 (1) ◽  
pp. 8
Author(s):  
Muhammad Qayash Khan ◽  
Muhammad Zubair Anjum ◽  
Shamim Akhter ◽  
Irfan Khattak ◽  
Abid Ali
Keyword(s):  
Diet Composition ◽  
Feeding Activity ◽  
Fish Fauna ◽  
Feeding Habit ◽  
Gut Contents ◽  
Catch Per Unit Effort ◽  
Food Items ◽  
Unit Effort ◽  
Significant Difference ◽  
River Indus

Background:Schizothorax plagiostomus is widely distributed in river Indus and is most important food fish in Pakistan. The feeding habit of fish is directly related to the size of fish, its metabolic rate and environmental temperature. The accurate description of fish diet and feeding habit is a very important aspect in fisheries management for the purpose of species conservation, breeding and culture. The present work was aimed to investigate the specie abundance, the diet composition and seasonal variations in the feeding habit of Snow barbell Schizothorax plagiostomus.Materials, Methods & Results: A total of 1799 fish specimens were caught at the confluence of six tributaries along river Indus at Indus Kohistan, northeastern Pakistan. The fish were collected by 5-panels of gill net during first week of each month. The site specific Catch Per Unit Effort (CPUE) and season specific CPUE of fish fauna were assessed. For the gut content analysis 240 samples (99 male and 141 females) of S. plagiostomus were selected on monthly basis. Frequency of occurrence method and volumetric method were applied to record the different food items in the gut of S. plagiostomus. The physico-chemical parameters, NO3 concentration and dissolved Co2 of water from different localities of river Indus were recorded month wise by Hach sensION 156 meter, Horiba LAQUA Nitrate Meter and EA80 meter respectively. Significant difference was observed in water temperature during the four seasons. Except alkalinity no other water parameter showed significant variation across different localities. The results showed that highest Mean CPUE was observed for Darel Stream (0.55) and lowest for Jalkot stream (0.26). Peak abundance of fish was recorded in the month of November with a mean catch of 44.50, mean CPUE of 0.74 and mean Kruskal-Wallis rank value of 63.25. Spirogyra and Ulothrix occurred as maximum food items in the gut of S. plagiostomus during summer while their minimum amount occurred during autumn. According to the ranking index spirogyra and ulothrix ranked higher with significant difference in comparison to other food items. The results showed that S. plagiostomus is phytophagous in its feeding habit, which consumed mainly algae attached to stones and pebbles during the whole year. However, the presence of some secondary items such as animal matter, detritus, sand and mud might be due to the distinct availabilities of food along the seasons. The highest feeding activity of S. plagiostomus was recorded during summer while the lowest one occurred during autumn, spring and winter. Discussion: Catch per unit effort (CPUE) is an indirect measure of the abundance of a target species. It is used as an index of stock abundance in fisheries and conservation biology. During the study low fish fauna was found in River Indus as reported previously. Majority of the fish occurred in snow fed river tributaries in the study area as these tributaries are comparatively less turbulent. Previous studies have also recorded that Schizothoracine generally prefer clean waters. The present findings of gut contents analysis showed clearly that S. plagiostomus is a phytophagous fish which scrap and consumed spirogyra and ulothrix attached to stones and pebbles. Earlier it was reported that mouth of S. plagiostomusis is inferior, wide, with deep lower jaw having keratinized cutting edge and the lower lip is folded and expanded with numerous papillae making it best suited for scrapping algae attached to stones and pebbles. The highest feeding activity was observed during warmer months as compared to cold months. S. plagiostomus spawn twice in a year in autumn and in spring. The highest feeding activity of S. plagiostomus seems to be link with a reflex of recovery strategy due to physiological process of gonadal development.

Seasonal Changes in the Germination Responses of Buried Witchgrass (Panicum capillare) Seeds

Weed Science ◽  
1986 ◽  
Vol 34 (1) ◽  
pp. 22-24 ◽  
Author(s):  
Jerry M. Baskin ◽  
Carol C. Baskin
Keyword(s):  
Seasonal Changes ◽  
Late Summer ◽  
Late Spring ◽  
Seasonal Temperature ◽  
Temperature Changes ◽  
Late Autumn ◽  
Buried Seeds ◽  
Autumn And Winter

Buried seeds of witchgrass (Panicum capillare L., # PANCA) exposed to natural seasonal temperature changes in Lexington, KY, for 0 to 35 months exhibited annual dormancy/nondormancy cycles. Seeds were dormant at maturity in early October. During burial in late autumn and winter, fresh seeds and those that had been buried for 1 and 2 years became nondormant. Nondormant seeds germinated from 76 to 100% in light at daily thermoperiods of 15/6, 20/10, 25/15, 30/15, and 35/20 C, while in darkness they germinated from 1 to 24%. In late spring, seeds lost the ability to germinate in darkness, and by late summer 63 to 100% of them had lost the ability to germinate in light. As seeds became nondormant, they germinated (in light) at high (35/20, 30/15 C) and then at lower (25/15, 20/10, and 15/6 C) temperatures. As seeds reentered dormancy, they lost the ability to germinate (in light) at 15/6 C and at higher thermoperiods 2 to 3 months later.

Observations on the Luminescence of the Larval Glowworm, Lampyris noctiluca L. (Col. Lampyridae)

1974 ◽  
Vol 5 (2) ◽  
pp. 103-109 ◽  
Author(s):  
Hans Dreisig
Keyword(s):  
Adult Female ◽  
Full Moon ◽  
Late Summer ◽  
Active Period ◽  
Ambient Illumination ◽  
Experimental Conditions ◽  
Adult Females ◽  
The Difference

AbstractThe larval luminescence in L. noctiluca consists in a glow lasting for several seconds (average 7.3 sec.) emitted at irregular intervals while the animal is crawling about during the active period at night. In the adult female the glow is continuous often for several hours. Also some larvae in the last instar were able to glow continuously for hours. Onset of activity in the larvae occurred at a lower critical ambient illumination (6.85 log lux +10) than in adult females (10.10 log lux+10). The dispersion of onsets was greater in larvae than in females. The duration of luminescent activity in the field was ca. 5 hours and at experimental conditions ca. 8 hours. In thc field larvae were mostly seen during late summer, probably because of the low critical illumination, which was also the reason why activity was suspended on moonlit nights. The intensity of moonlight around full moon was ca. 8.00—9.00 log lux+10. In the discussion the following subjects are treated: The function of larval luminescence; the reaction of larvae to ambient illumination; and the difference between glowing and flashing.

scholarly journals Composition of late summer diet by semi-domesticated reindeer in different grazing conditions in northernmost Finland

Rangifer ◽  
2015 ◽  
Vol 35 (1) ◽  
pp. 39-52 ◽  
Author(s):  
Pauline Bezard ◽  
Sophie Brilland ◽  
Jouko Kumpula
Keyword(s):  
Diet Composition ◽  
Rangifer Tarandus ◽  
Coniferous Forest ◽  
Late Summer ◽  
Early Spring ◽  
Food Plants ◽  
Sample Site ◽  
Rotation System ◽  
Plant Groups ◽  
Microhistological Analysis

 This study aims to investigate the diet composition of semi-domesticated reindeer (Rangifer tarandus tarandus) in late summer in different kinds of grazing conditions in northernmost Finland. The composition of diet by reindeer was determined on the grounds of microhistological analysis of feces samples collected in early August in different seasonal grazing areas (winter or summer/year-round grazing areas) in three reindeer management districts. Although the proportion of different plant groups varied between the studied districts, the quantified group of ground lichens (which also contained small amounts of mushrooms) was the most abundant, varying from 33.0 to 46.4% in the analyzed samples. In general, there were significant differences in the proportions of lichen between districts, but not between grazing areas. The proportion of lichen in samples increased significantly when the amount of lichen pasture around a sample site increased. The proportion of dwarf shrubs and leaves in samples varied from 24.9 to 37.9% and differed significantly between districts, but not between grazing areas. In the same way, the proportion of graminoids varied between 20.9 and 36.2% and differed significantly between districts and also between grazing areas. Higher amounts of graminoids in feces were observed in summer/year-round grazing areas than in winter grazing areas. Finally, the proportion of bryophytes varied between 2.9 and 6.5% and was significantly different between districts, but not between grazing areas. An increase in old and mature coniferous forest around a sample site significantly increased the amounts of bryophytes in samples. The results indicate that reindeer adapt their summer diet composition according to the availability of food plants. The results also show that when reindeer are allowed to select their summer ranges freely, reindeer tend to use lichen pastures intensively also during summer, which causes a considerable reduction in lichens due to grazing and trampling. Therefore, a proper seasonal pasture rotation system to protect lichen pastures from grazing and trampling, from early spring to late autumn, is an essential part of sustainable pasture use in reindeer herding.

scholarly journals Winter Carnivory and Diapause Counteract the Reliance on Ice Algae by Barents Sea Zooplankton

2021 ◽  
Vol 8 ◽  
Author(s):  
Doreen Kohlbach ◽  
Katrin Schmidt ◽  
Haakon Hop ◽  
Anette Wold ◽  
Amalia Keck Al-Habahbeh ◽  
...  
Keyword(s):  
Sea Ice ◽  
Barents Sea ◽  
Feeding Activity ◽  
Carbon Sources ◽  
Late Summer ◽  
Rapid Decline ◽  
Amphipod Species ◽  
Ice Algae ◽  
Sea Ice Extent ◽  
Sea Ice Algae

The Barents Sea is a hotspot for environmental change due to its rapid warming, and information on dietary preferences of zooplankton is crucial to better understand the impacts of these changes on food-web dynamics. We combined lipid-based trophic marker approaches, namely analysis of fatty acids (FAs), highly branched isoprenoids (HBIs) and sterols, to compare late summer (August) and early winter (November/December) feeding of key Barents Sea zooplankters; the copepods Calanus glacialis, C. hyperboreus and C. finmarchicus and the amphipods Themisto libellula and T. abyssorum. Based on FAs, copepods showed a stronger reliance on a diatom-based diet. Phytosterols, produced mainly by diatoms, declined from summer to winter in C. glacialis and C. hyperboreus, indicating the strong direct linkage of their feeding to primary production. By contrast, C. finmarchicus showed evidence of year-round feeding, indicated by the higher winter carnivory FA ratios of 18:1(n-9)/18:1(n-7) than its larger congeners. This, plus differences in seasonal lipid dynamics, suggests varied overwintering strategies among the copepods; namely diapause in C. glacialis and C. hyperboreus and continued feeding activity in C. finmarchicus. Based on the absence of sea ice algae-associated HBIs (IP25 and IPSO25) in the three copepod species during both seasons, their carbon sources were likely primarily of pelagic origin. In both amphipods, increased FA carnivory ratios during winter indicated that they relied strongly on heterotrophic prey during the polar night. Both amphipod species contained sea ice algae-derived HBIs, present in broadly similar concentrations between species and seasons. Our results indicate that sea ice-derived carbon forms a supplementary food rather than a crucial dietary component for these two amphipod species in summer and winter, with carnivory potentially providing them with a degree of resilience to the rapid decline in Barents Sea (winter) sea-ice extent and thickness. The weak trophic link of both zooplankton taxa to sea ice-derived carbon in our study likely reflects the low abundance and quality of ice-associated carbon during late summer and the inaccessibility of algae trapped inside the ice during winter.

Feeding of tub gurnard Chelidonichthys lucerna (Scorpaeniformes: Triglidae) in the north-east Mediterranean

2011 ◽  
Vol 92 (3) ◽  
pp. 605-612 ◽  
Author(s):  
Marco Stagioni ◽  
Stefano Montanini ◽  
Maria Vallisneri
Keyword(s):  
Diet Composition ◽  
Foraging Behaviour ◽  
Adriatic Sea ◽  
Feeding Habits ◽  
Feeding Activity ◽  
Stomach Contents ◽  
East Mediterranean ◽  
North East ◽  
The North ◽  
Important Prey

The stomach contents of 1096 specimens of Chelidonichthys lucerna were examined in order to analyse their diet composition according to fish size, sex, depth and season. Sampling was carried out from May 2005 to March 2007 during several bottom trawl surveys in the Adriatic Sea (north-east Mediterranean). Feeding activity was more intense in juveniles than in adults. The most important prey was Crustacea (mainly Decapoda: Brachyura, such as Goneplax rhomboides, Liocarcinus spp., Philocheras spp.) and Teleostei (mainly European anchovy Engraulis encrasicolus and black goby Gobius niger). There was no difference between male and female diet. Feeding habits varied with size, with fish dominating the stomach contents of larger specimens. Finally, fish increased in winter and crustaceans in summer. Chelidonichthys lucerna shows a generalist and opportunistic foraging behaviour, preying mainly epibenthic and nectobenthic organisms.

Feeding of the spider crab Maja squinado in rocky subtidal areas of the Ría de Arousa (north-west Spain)

2000 ◽  
Vol 80 (1) ◽  
pp. 95-102 ◽  
Author(s):  
C. Bernárdez ◽  
J. Freire ◽  
E. González-Gurriarán
Keyword(s):  
Diet Composition ◽  
Feeding Activity ◽  
Paracentrotus Lividus ◽  
Dry Weight ◽  
Seasonal Abundance ◽  
Gut Contents ◽  
Moult Cycle ◽  
Spider Crab ◽  
North West ◽  
Rocky Subtidal

The diet of the spider crab, Maja squinado, was studied in the rocky subtidal areas of the Ría de Arousa (Galicia, north-west Spain), by analysing the gut contents of crabs caught in the summer and winter of 1992. The highly diverse diet was made up primarily of macroalgae and benthic invertebrates that were either sessile or had little mobility. The most important prey were the seaweeds Laminariaceae (43% of the frequency of occurrence and 15% of the food dry weight), Corallina spp. (38% and 3%), molluscs [the chiton Acanthochitona crinitus (15% and 1%), the gastropods Bittium sp. (30% and 2%), Trochiidae and others and the bivalve Mytilus sp. (32% and 12%)], echinoderms [the holothurian Aslia lefevrei (32% and 18%) and the echinoid Paracentrotus lividus (16% and 7%)] and solitary ascidians (18% and 6%). The variability in diet composition was determined by the season (Laminariaceae, Corallina spp., P. lividus, Mytilus sp., gastropods and chitons appeared in greater frequency in winter, while the solitary ascidians and A. lefevrei were consumed to a greater extent in summer) in addition to sexual maturity (prey such as Bittium sp. or Trochiidae were more common in juveniles). Moreover, the changes in the food consumption rate were linked primarily to the moult stage. Feeding activity plummeted during the phases immediately preceding and following ecdysis (stages D0–D3–4 and A), and the diet was less diverse during these phases. No feeding differences were found that could be linked to sex. The composition of the diet of Maja squinado appears to be determined by the seasonal abundance of the different prey in subtidal rocky areas and by their availability (depending on their behavioural and anatomical characteristics, mainly mobility and the presence of hard external structures). Moreover, life history factors have little importance in the variability of the diet composition and only the moult cycle has a considerable effect on feeding rate.

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