Impact of Harvesting on Irish Moss (Chondrus crispus Stackhouse) Frond Size-Class Structure

1988 ◽  
Vol 45 (5) ◽  
pp. 767-773 ◽  
Author(s):  
J. D. Pringle ◽  
R. E. Semple
Keyword(s):  
Dry Weight ◽  
Size Class ◽  
Class Structure ◽  
Chondrus Crispus ◽  
Branch Number ◽  
Frequency Distributions ◽  
Class Frequency ◽  
Irish Moss ◽  
The Mean ◽  
Frond Length

Irish moss (Chondrus crispus Stackhouse) is cropped annually by dragrakes in certain southern Gulf of St. Lawrence Marine Plant Harvesting Districts (MPHD). Mean annual yield declined between 1972 and 1979, from peak years 1966–71, through a standing crop decrease. The present study compares frond size-class structure between three dragraked districts (light, moderate, and intense harvesting pressure) and two non-dragraked districts. Fronds, sampled by hand, were classified by pattern of dichotomy (branch) number; both mean frond weight and length were determined for each district. Frond size-class frequency distributions were bimodal from the moderate and intensely dragraked districts. Densities peaked at Classes 0 (no branching) and 5 or 6 (five or six branches), mean frond dry weights ranged from 0.09 g (intensely dragraked) to 0.18 g, mean frond length was between ~7 and ~10 cm, and mean frond dichotomy number was between ~3.6 and ~5.2. Frond size-class frequency distributions were unimodal from the non-dragraked and lightly dragraked districts, peaks were at Classes 6–8, mean frond dry weight per district was 0.40 g, mean frond length was between ~8 and ~12 cm, and mean frond dichotomy number was 7.5–8.2. The hypothesis that frond size-class frequency, mean frond dry weights, and mean frond dichotomy number were similar between intensely dragraked and non-dragraked beds was rejected. It was concluded that annual yield in the former beds would be substantially higher, were the mean frond size-class of the harvest increased by even one dichotomy. Frond length per class was not significantly different between intensely dragraked and non-dragraked beds. However, fronds higher than Class 6 from the former beds were heavier than those from the latter beds. These results are discussed in relation to dragrake selection pressure.

scholarly journals Size-class structure of the forests of Finland during 1921–2013: a recovery from centuries of exploitation, guided by forest policies

2019 ◽  
Vol 139 (2) ◽  
pp. 279-293
Author(s):  
Helena M. Henttonen ◽  
Pekka Nöjd ◽  
Susanne Suvanto ◽  
Juha Heikkinen ◽  
Harri Mäkinen
Keyword(s):  
Land Use ◽  
Geographical Area ◽  
Species Group ◽  
Size Class ◽  
Class Structure ◽  
Initial State ◽  
Frequency Distributions ◽  
Size Classes ◽  
Growing Stock ◽  
Large Trees

AbstractFrequency distributions of tree diameters are a powerful tool for analyzing changes of tree populations in large areas. We analyzed the densities and mean volume estimates of trees in different size classes for the Finnish forests over the time-span of the National Forest Inventories (1921–2013). The results display a general increase in trees in all size classes, species group and geographical area, mainly after the 1970s. The densities of medium- and large-sized conifers showed large increases in the southern boreal subzone, spruces even more than pines. Small- to medium-sized pines have increased in the middle and northern boreal subzones. The shifts in growing stock are related to changing land use, resulting from the development of the society. The low quantities of both growing stock and large trees during the 1920s reflect a poor initial state of forests. Several land use forms of the former agriculture-based society were detrimental to forests, including slash and burn agriculture, cattle grazing and tar production. The pressure from alternative land use forms was stronger in southern Finland, where the population density (people per km2) is much higher. Between 1971 and 2013, the changes in size-class structure can be attributed mainly to intensified silviculture boosted by actions of the Finnish governments, including both legislation and financial support for management activities. Not only the development of growing stock has exceeded expectations, but the increase has also concentrated in the economically valuable trees in the large size classes.

EFFECTS OF CHONDRUS CRISPUS ON FERTILITY, PREGNANCY, AND POST-NATAL WELFARE OF SHROPSHIRE EWES

1974 ◽  
Vol 54 (1) ◽  
pp. 41-45
Author(s):  
D. BREWER ◽  
J. McLACHLAN ◽  
A. C. NEISH ◽  
P. F. SHACKLOCK ◽  
A. TAYLOR ◽  
...  
Keyword(s):  
Weight Gain ◽  
Dose Level ◽  
Daily Weight Gain ◽  
Chondrus Crispus ◽  
Control Groups ◽  
Irish Moss ◽  
The Mean ◽  
Fleece Weight

Shropshire ewes, aged 4 to 9 years, were dosed once weekly with Chondrus crispus (Irish moss) grown in large tanks in a greenhouse. The seaweed was fed at two levels (250 and 500 g wet wt/wk) by an oesophageal tube within 4 h of harvest from the tanks. Four to 8 wk after dosing commenced the ewes were tupped, and the dosing continued until 1 wk before parturition. Few differences were noticed in the two dosed groups. Nineteen lambs were obtained from 12 dosed ewes and 15 lambs from 12 controls. The mean loss in weight of the dosed ewes in the 4 wk following parturition was 0.50 kg/day and the corresponding loss by the controls was 0.45 kg/day. In the same period the mean daily weight gain of the lamb was 0.25 kg for the singles from both groups, 0.18 kg for the twins from the dosed sheep, and 0.21 kg for the twins from the controls. At shearing the dosed ewes gave a mean fleece weight of 3.09 kg, whereas the control groups had an average fleece weight of 3.57 kg. It is concluded that at the dose level used C. crispus was not acutely toxic.

scholarly journals Growth and population biology of the sand-bubbler crab Scopimera crabricauda Alcock 1900 (Brachyura: Dotillidae) from the Persian Gulf, Iran

2021 ◽  
Vol 82 (1) ◽  
Author(s):  
Sana Sharifian ◽  
Vahid Malekzadeh ◽  
Ehsan Kamrani ◽  
Mohsen Safaie
Keyword(s):  
Persian Gulf ◽  
Population Biology ◽  
Slow Growth ◽  
Carapace Width ◽  
Population Data ◽  
Natural Mortality ◽  
Frequency Distributions ◽  
Iranian Coast ◽  
The Mean ◽  
The Persian Gulf

Abstract Background Dotillid crabs are introduced as one common dwellers of sandy shores. We studied the ecology and growth of the sand bubbler crab Scopimera crabricauda Alcock, 1900, in the Persian Gulf, Iran. Crabs were sampled monthly by excavating nine quadrats at three intertidal levels during spring low tides from January 2016 to January 2017. Results Population data show unimodal size-frequency distributions in both sexes. The Von Bertalanffy function was calculated at CWt = 8.76 [1 − exp (− 0.56 (t + 0.39))], CWt = 7.90 [1 − exp (− 0.59 (t + 0.40))] and CWt = 9.35 [1 − exp (− 0.57 (t + 0.41))] for males, females, and both sexes, respectively. The life span appeared to be 5.35, 5.07, and 5.26 years for males, females, and both sexes, respectively. The cohorts were identified as two age continuous groups, with the mean model carapace width 5.39 and 7.11 mm for both sexes. The natural mortality (M) coefficients stood at 1.72 for males, 1.83 for females, and 1.76 years−1 for both sexes, respectively. The overall sex ratio (1:0.4) was significantly different from the expected 1:1 proportion with male-biased. Recruitment occurred with the highest number of annual pulse once a year during the summer. Conclusions The results, which show slow growth, emphasize the necessity of proper management for the survival of the stock of S. crabricauda on the Iranian coast of the Persian Gulf.

scholarly journals Admixing Chaff with Straw Increased the Residues Collected without Compromising Machinery Efficiencies

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1766 ◽  
Author(s):  
Alessandro Suardi ◽  
Sergio Saia ◽  
Walter Stefanoni ◽  
Carina Gunnarsson ◽  
Martin Sundberg ◽  
...  
Keyword(s):  
Energy Production ◽  
Dry Weight ◽  
Global Scale ◽  
Unit Weight ◽  
Residual Biomass ◽  
Energy Needs ◽  
The Mean ◽  
Field Efficiency ◽  
The One ◽  
Staple Crop

The collection of residues from staple crop may contribute to meet EU regulations in renewable energy production without harming soil quality. At a global scale, chaff may have great potential to be used as a bioenergy source. However, chaff is not usually collected, and its loss can consist of up to one-fifth of the residual biomass harvestable. In the present work, a spreader able to manage the chaff (either spreading [SPR] on the soil aside to the straw swath or admixed [ADM] with the straw) at varying threshing conditions (with either 1 or 2 threshing rotors [1R and 2R, respectively] in the combine, which affects the mean length of the straw pieces). The fractions of the biomass available in field (grain, chaff, straw, and stubble) were measured, along with the performances of both grain harvesting and baling operations. Admixing chaff allowed for a slightly higher amount of straw fresh weight baled compared to SPR (+336 kg straw ha−1), but such result was not evident on a dry weight basis. At the one time, admixing chaff reduced the material capacity of the combine by 12.9%. Using 2R compared to 1R strongly reduced the length of the straw pieces, and increased the bale unit weight; however, it reduced the field efficiency of the grain harvesting operations by 11.9%. On average, the straw loss did not vary by the treatments applied and was 44% of the total residues available (computed excluding the stubble). In conclusion, admixing of chaff with straw is an option to increase the residues collected without compromising grain harvesting and straw baling efficiencies; in addition, it can reduce the energy needs for the bale logistics. According to the present data, improving the chaff collection can allow halving the loss of residues. However, further studies are needed to optimise both the chaff and the straw recoveries.

Reference points for the length-based indicator Lmax5% for use in the assessment of data-limited stocks

2019 ◽  
Vol 76 (7) ◽  
pp. 2125-2139 ◽  
Author(s):  
Tanja Miethe ◽  
Yves Reecht ◽  
Helen Dobby
Keyword(s):  
Life Histories ◽  
Stock Assessment ◽  
Reference Points ◽  
Length Frequency ◽  
Frequency Distributions ◽  
Simulation Tools ◽  
Spawning Potential Ratio ◽  
The Mean ◽  
Commercial Sources ◽  
Length Frequency Data

Abstract In the absence of abundance indices from scientific surveys or commercial sources, reliable length frequency data from sampled commercial catches can be used to provide an indirect assessment of fishing mortality. Length-based indicators are simple metrics which describe length frequency distributions. The length-based indicator Lmax5%, the mean length of the largest 5% of individuals in the catch, combined with appropriately selected reference points, can be used to evaluate the presence of very large individuals in the catch and hence determine exploitation level. Using analytical per-recruit models, we derive reference points consistent with a spawning potential ratio of 40%. The reference points depend on the life history parameters for natural mortality, maturity, and growth (M, Lmat, L∞, k, CVL∞). Using available simulation tools, we investigate the sensitivity of the reference points to errors in these parameters and explore the usefulness of particular reference points for management purposes for stocks with different life histories. The proposed reference points are robust to uncertainty in length at first capture, Lc, and take into account the maturation schedule of a species. For those stocks with high M/k ratios (>1), Lmax5%, combined with the appropriate reference point, can be used to provide a data-limited stock assessment.

scholarly journals Evaluating the Sensitivity and Efficacy of Fungicides with Different Modes of Action Against Botryosphaeria dothidea

Plant Disease ◽  
2018 ◽  
Vol 102 (9) ◽  
pp. 1785-1793 ◽  
Author(s):  
Yingying Song ◽  
Lili Li ◽  
Chao Li ◽  
Zengbin Lu ◽  
Xingyuan Men ◽  
...  
Keyword(s):  
Field Trials ◽  
Apple Fruit ◽  
Effective Concentration ◽  
Botryosphaeria Dothidea ◽  
Control Efficacy ◽  
Frequency Distributions ◽  
Considerable Potential ◽  
Ring Rot ◽  
Fungal Plant Pathogen ◽  
The Mean

Botryosphaeria dothidea, the causal agent of apple ring rot, is an important fungal plant pathogen that can cause serious reductions in crop yield, and fungicides still play a crucial role in management. In the present study, the sensitivity of B. dothidea to fludioxonil, fluazinam, and pyrisoxazole was assessed in 162 isolates. Moreover, the protective and curative activity of the three fungicides on detached apple fruit as well as the control efficacy in the field were determined. The results showed that the mean 50% effective concentration (EC50) values (± standard deviation) were 0.01 ± 0.008, 0.04 ± 0.03, and 0.02 ± 0.01 μg ml−1, with individual EC50 values of 0.002 to 0.05, 0.003 to 0.19, and 0.005 to 0.26 μg ml−1 for fludioxonil, fluazinam, and pyrisoxazole, respectively. In addition, the frequency distributions of EC50 values were both unimodal curves. However, significant correlations (P < 0.05) were found between fludioxonil and iprodione, between fluazinam and iprodione, as well as between pyrisoxazole and difenoconazole. In field trials conducted during 2016 and 2017, the control efficacy ranged from 75.91 to 87.41% when fludioxonil was applied at 100 to 150 mg active ingredient (a.i.) kg−1, 81.90 to 85.13% when fluazinam was applied at 400 mg a.i. kg−1, and 77.43 to 80.97% when pyrisoxazole was applied at 400 mg a.i. kg−1. The control efficacy of the fungicides in storage was higher than 60%, with the exception of fluazinam. These results demonstrated that fludioxonil, fluazinam, and pyrisoxazole have considerable potential to control apple ring rot.

THE EFFECT OF INGESTED CHLORTETRACYCLINE ON SOME HYDROLASES AND ORGANS ASSOCIATED WITH THE DIGESTIVE PROCESS IN GROWING PIGS: II. PROTEASE, AMYLASE, AND GELLULASE ACTIVITY OF THE CONTENTS OF THE SMALL INTESTINE AND OF THE CECUM; WEIGHTS OF SMALL INTESTINE AND MUCOSA

1957 ◽  
Vol 35 (3) ◽  
pp. 195-202 ◽  
Author(s):  
M. A. A. Vonk ◽  
L. W. McElroy ◽  
R. T. Berg
Keyword(s):  
Small Intestine ◽  
Dry Matter ◽  
Cellulase Activity ◽  
Dry Weight ◽  
Growing Pigs ◽  
Weanling Pigs ◽  
Intestinal Contents ◽  
Wet Weight ◽  
The Mean ◽  
Ad Libitum

Four treatments, involving differences in method of feeding and interval between last feed and slaughter, were employed in a study of the effect of dietary chlortetracycline on protease, amylase, and cellulase activity in the intestinal and cecal contents of 16 pairs of weanling pigs. Most consistent results were obtained with six pairs which were limited pair-fed except for the final feeding during which feed was available ad libitum for a 4-hour period ending 18 hours before slaughter. The mean total activities of all three hydrolases in the contents of the small intestines and of the ceca of the antibiotic-fed animals of these six pairs were significantly greater than in those of the control animals. Expressed as activity per gram dry matter of intestinal contents, significantly higher values for protease and amylase, but not for cellulase, were observed in the pigs that had received chlortetracycline. When the combined results obtained from all 16 pairs of the experimental animals were analyzed, the results showed that on a basis of activity per gram dry matter of intestinal contents, ingested chlortetracycline was associated with significant increases in amylase and cellulase but not in protease activity. Protease, amylase, and cellulase activities per gram dry matter of cecal contents were higher for pigs fed the antibiotic than for their controls. The mean wet weight of the empty small intestine and the mean dry weight of the mucosa scraped from the anterior 3-meter section of the small intestine were lower for the chlortetracycline-fed animals, but the differences were not statistically significant.

scholarly journals Use of the copepod Oithona hebes as a bioencapsulator of essential fatty acids

2015 ◽  
Vol 63 (3) ◽  
pp. 331-336 ◽  
Author(s):  
Marcia Vanacor Barroso ◽  
Breno Barroso Boos ◽  
Rosemar Antoniassi ◽  
Luiz Fernando Loureiro Fernandes
Keyword(s):  
Essential Fatty Acids ◽  
Subsurface Layer ◽  
Dry Weight ◽  
Estuarine System ◽  
Chaetoceros Gracilis ◽  
Final Population ◽  
Freeze Dried ◽  
The Mean ◽  
Conical Tanks ◽  
Made In

AbstractThe advantages of using copepods in aquaculture include nutritional superiority, high digestibility and broad spectrum of sizes, with the possibility of bioencapsulation of nutrients, probiotics and medicines. This study aimed to compare the effects of feeding copepods with a microalgae diet and two commercial inert diets on the copepod culture performance and their fatty acid profile. Wild copepods were collected in the estuarine system of Piraquê-açu River, Aracruz, Espírito Santo, Brazil, with a conical net of 60 cm in diameter and 200 μm mesh with a blind cup end, towed through the subsurface layer at a speed of 1 knot for 5 minutes. Once collected, the material was sieved in order to select only Oithona hebes. The experiment was conducted in nine cylindrical-conical tanks with a 60 L capacity, salinity of 25.8 ± 1.3, temperature of 25.5 ± 0.5 ºC and weak aeration, stocked with a density of 1.5 copepod/mL. Treatments were made in triplicate and consisted of: Treatment 1 (Control) fed with microalgae Chaetoceros gracilis and Nannochloropsis oculata (1:1) with 50,000 cells.mL-1each; Treatment 2 with S.Parkle® INVE (1g.million-1); and Treatment 3 with freeze-dried spirulina (1g.million-1). The mean final population was compared by a Tukey test (p < 0.05). Results showed higher population growth for copepods treated with S.parkle, which was the only treatment that presented copepodites. S.parkle was a good source of total lipids (9.54 g.100g-1 dry weight), high availability of DHA, EPA and had a good DHA:EPA:ARA ratio of 12.4:3.4:1.0. Copepods that were fed S.parkle had the highest DHA levels and a DHA:EPA:ARA ratio of 15.4:2.2:1.0. This study showed that S.parkle is a good inert food for rearing the copepod O. hebes, demonstrating the ability of copepods to bioencapsulate nutrients, allowing their transfer in the food chain.

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