Seasonal patterns of growth, alginate content and block structure of the alien invader Sargassum muticum (Fucales, Ochrophyta) from the Atlantic coast of Morocco

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Zahira Belattmania ◽  
Samir El Atouani ◽  
Fouad Bentiss ◽  
Charafeddine Jama ◽  
Annalisa Falace ◽  
...  
Keyword(s):  
Vegetative Growth ◽  
Block Structure ◽  
Atlantic Coast ◽  
Late Summer ◽  
Early Summer ◽  
Sargassum Muticum ◽  
Early Autumn ◽  
Commercial Applications ◽  
Alien Invader ◽  
G Ratio

Abstract In the present study, alginate yield and composition were investigated during the seasonal life cycle of the alien brown alga Sargassum muticum harvested from the Atlantic coast of Morocco. Alginate yield ranged from 11.14% in winter to 25.62% in spring/early summer, coinciding with maximum vegetative growth. Monthly monitoring of the alginate block structure showed that the highest mannuronate (M)/guluronate (G) ratio was recorded during the maximum development of S. muticum, before sexual maturity and during resumption of vegetative growth, giving maximum flexibility to the alga. The unusually high molar monad fractions (FG) and dyad fractions (FGG) of guluronic acid in late summer/early autumn appeared to be related to stiffness of senescent thalli. Rheological characterisation showed that the alginate of S. muticum exhibited pseudoplastic behaviour, with the highest apparent viscosities measured in late summer/early autumn when the G blocks dominated the alginate structure. This study suggests that S. muticum could be exploited as an alginophyte for commercial applications. The best harvest time is May-June, which corresponds to the highest alginate yield, maximum thallus growth, and largely completed sexual reproduction, ensuring sustainable exploitation of the species.

Clivia mirabilis (Amaryllidaceae: Haemantheae) a new species from Northern Cape, South Africa

Bothalia ◽  
2002 ◽  
Vol 32 (1) ◽  
pp. 1-7 ◽  
Author(s):  
J. P. Rourke
Keyword(s):  
South Africa ◽  
New Species ◽  
Vegetative Growth ◽  
Mediterranean Climate ◽  
Nature Reserve ◽  
Late Summer ◽  
Distribution Area ◽  
Early Autumn ◽  
Northern Cape ◽  
A New Species

Clivia mirabilis Rourke is a new pendulous tubular-flowered species from Oorlogskloof Nature Reserve in Northern Cape. Its distribution area is some 800 km outside the previously accepted range of the genus Clivia. This sun-tolerant species is adapted to an arid Mediterranean climate, producing vegetative growth in winter and maturing its seeds rapidly in late summer/early autumn to synchronize with the arrival of winter rains.

scholarly journals Spatiotemporal patterns of phenology of the alien Phaeophyceae Sargassum muticum on the Atlantic coast of Morocco

2021 ◽  
Vol 85 (2) ◽  
pp. 103-111
Author(s):  
Samir El Atouani ◽  
Zahira Belattmania ◽  
Soukaina Kaidi ◽  
Aschwin H. Engelen ◽  
Ester A. Serrão ◽  
...  
Keyword(s):  
Life Cycle ◽  
Atlantic Coast ◽  
Early Summer ◽  
Spatiotemporal Patterns ◽  
Sargassum Muticum ◽  
Growth Phases ◽  
Sandy Bottom ◽  
Body Depth ◽  
Rocky Substratum ◽  
High Elongation

The present study focused on the dynamics of the phenology and life cycle of the Phaeophyceae invader Sargassum muticum at three sites on the Atlantic coast of Morocco over a period of two years (2013 and 2014). The results showed that S. muticum has two distinct growth phases; one with slower growth in winter followed by one with faster growth in spring-early summer, when the species exhibited high elongation and branching activities with thalli length ranging from 1 to more than 5 m depending on the study site. The site S1, with a rocky substratum covered by submerged sands, promotes thalli elongation, with maximum lengths of 643.33 11.10 cm recorded in July. At the rocky sites (S2 and S3), the maximum length of the seaweed depends on the pools’ depth. Although the elongation of thalli is enhanced by the water body depth, the settlements’ density (5-48 ind. m–2) seems to be mainly related to the nature of the substrate. The maturity index progressively increases from spring to early summer, when it reaches the highest values. S. muticum seems to be more abundant and more easily acclimated in shallow rockpools (sufficiently lighted and semi-exposed to wave action at the mid and lower tidal levels) than in protected sandy bottom sites with low hydrodynamic forces.

Airborne observations of surface cloud radiative forcing over different surface types of the Arctic Ocean during late summer/early autumn

2021 ◽  
Author(s):  
Sebastian Becker ◽  
Johannes Stapf ◽  
André Ehrlich ◽  
Michael Schäfer ◽  
Manfred Wendisch
Keyword(s):  
Sea Ice ◽  
Radiative Forcing ◽  
Late Summer ◽  
Early Summer ◽  
Open Ocean ◽  
The Arctic ◽  
Radiative Energy ◽  
Cloud Radiative Forcing ◽  
Early Autumn ◽  
Sky Conditions

<p>Clouds can cause a significant change to the radiative energy budget of the Earth's surface compared to clear-sky conditions, which is referred to as surface cloud radiative forcing (CRF). The CRF in the Arctic strongly depends on the surface properties (absorbing open ocean vs. strongly reflecting sea ice) and is affected by the low or even absent sun and the special thermodynamic conditions. Therefore, in contrast to the mid and low latitudes, in the Arctic, clouds mostly warm the surface on annual average. However, the CRF will change as the sea ice retreats in a warming climate, which might be accelerated due to the enhanced warming of the Arctic, known as Arctic Amplification. Thus, to quantify the contrast of the CRF over sea ice-covered and sea ice-free ocean surfaces, several airborne campaigns have been conducted in the vicinity of Svalbard in the recent years. The measurements of cloud macrophysical and microphysical properties as well as radiative and turbulent fluxes cover different seasons (spring to early autumn).</p><p>Airborne broadband radiation measurements under all-sky conditions were used to calculate the surface CRF during low-level flight sections. In this study, observations from the concurrent campaigns Multidisciplinary drifting Observatory for the Study of Arctic Climate – Airborne observations in the Central Arctic (MOSAiC-ACA) and MOSAiC-Icebird, conducted in August/September 2020, are presented. First results of the CRF over open ocean and the marginal sea ice zone (MIZ) of late summer/early autumn conditions are assessed and compared to the previous airborne spring and early summer campaigns to analyse the seasonal variability of the CRF.</p>

Effects of Dried Distillers’ Grains Cube Supplementation for Steers Grazing Introduced Pastures on Animal Performance and Forage Production

2021 ◽  
Vol 99 (Supplement_2) ◽  
pp. 12-13
Author(s):  
Jordan Adams ◽  
Rodney Farris ◽  
Scott Clawson ◽  
Earl Ward ◽  
Paul Beck
Keyword(s):  
Festuca Arundinacea ◽  
Statistical Power ◽  
Cynodon Dactylon ◽  
Animal Health ◽  
Late Summer ◽  
Early Summer ◽  
Distillers Grains ◽  
Forage Production ◽  
Trenbolone Acetate ◽  
Dried Distillers Grains

Abstract We evaluated the effects of supplementing dried distillers’ grains cubes (DDGS) and re-implantation of steers (n = 149; BW = 238 ± 13.8 kg) grazing tall fescue (Festuca arundinacea)/bermudagrass (Cynodon dactylon) pastures (n = 9 pastures, 7.2 ± 2.90 ha) from 14 April to 17 September 2020 (n = 155 d) in a split-plot design on steer performance and forage production. Main plot supplemental treatments (n = 3 pastures/treatment) included 1) Fertilized Control (FC), no supplementation on fertilized pastures (112 kg N/ha); 2) Fertilized Supplement (FS), supplemental DDGS fed at 2.9 kg 3-d/wk on fertilized pastures; and 3) Supplement (S), supplemented DDGS at 0.75% BW/d on unfertilized pastures prorated for 5-d/wk feeding. Steers were previously implanted during receiving with 40 mg trenbolone acetate and 8 mg estradiol (REV-G; Revalor G, Merck Animal Health). On July 7, steers in each pasture were randomly assigned to one of three re-implant treatments: 1) no re-implant; 2) REV-G; or 3) 200 mg progesterone and 20 mg estradiol (Synovex S, Zoetis Animal Health). Steers in FS and S gained more (P < 0.01) than FC throughout the trial and final BW was greater (P < 0.01) for FS and S compared with FC. Unexpectedly, re-implanting had no effect on ADG (P = 0.57) or BW (P = 0.34), but statistical power may be lacking. Supplemental efficiency was greater in the late summer for FS (P = 0.05) compared to S. Fertilizing pastures in FS and FC did not affect biomass (P = 0.39), however, CP was increased (P = 0.01) and acid and neutral detergent fibers tended to decrease (P = 0.06) relative to S in the early summer (April, May, June, and July), but did not differ in late summer (August and September). Based upon our analysis, DDGS is a suitable supplement and can replace N fertilizer for steers grazing introduced pastures.

scholarly journals 179 Using a 100% Dried Distillers Grains Cube as a Supplement for Steers Grazing Mixed Grass Prairie in Oklahoma

2020 ◽  
Vol 98 (Supplement_2) ◽  
pp. 46-46
Author(s):  
Zane N Grigsby ◽  
Paul A Beck ◽  
Stacey A Gunter
Keyword(s):  
Animal Health ◽  
Late Summer ◽  
Estradiol Benzoate ◽  
Positive Control ◽  
Negative Control ◽  
Early Summer ◽  
Trenbolone Acetate ◽  
Mixed Grass Prairie ◽  
Mixed Grass ◽  
Main Plot

Abstract This research was conducted to determine effects of supplementation and implanting on BW gain by steers grazing mixed grass prairie (n = 12 pastures, 19.9 ± 0.7 ha) in northwest Oklahoma. Three main plot treatments were: 1) Negative Control (NC), no supplementation, 2) Positive Control (PC), supplemented with DDGS cubes, 1.8 kg/steer on alternate days in late summer, 3) High Supplement (HS), 1/3 increase in stocking rate with 0.75% BW supplemental DDGS cubes all season. Steers (n = 125, BW = 223.1 ± 23.2 kg) were stocked at 2.2 ha/steer for PC and NC, 1.3 ha/steer for HS. Grazing was from May 17 – September 27 (132 d). All steers were implanted with 200 mg progesterone and 20 mg estradiol benzoate (SYN, Synonvex S, Zoetis Animal Health) on May 17. On July 18 three reimplant treatments were applied: 1) no reimplant; 2) SYN; or 3) 40 mg trenbolone acetate and 8 mg estradiol (Revalor G, Merck Animal Health). Data were analyzed using the PROC MIXED in SAS as a split-plot experimental design. In early summer HS had 0.26 kg greater (P < 0.01) ADG than NC and PC. Late summer gains of PC were 0.33 kg/d more (P ≤ 0.01) than NC; and HS gained 0.49 and 0.16 kg/day more (P ≤ 0.04) than NC and PC, respectively. Gain per hectare for PC (46 kg/ha) were greater (P < 0.01) than NC (35 kg/ha) and more than doubled (P < 0.01) with HS (89 kg/ha). Reimplanting had no effect on ADG (P ≥ 0.28). Late season supplementation with PC resulted in supplemental efficiency of 2.7 kg supplement/kg added gain compared with NC. Increased stocking rates with season long supplementation in HS resulted in supplemental efficiency of 3.8 kg supplement/kg added gain per hectare. Based on these data, a 100% DDGS cube is an effective supplement option to increase BW gain during the late summer or increase carrying capacity and gain during the summer grazing period in northwestern Oklahoma.

Replacing synthetic N with clovers or alfalfa in bermudagrass pastures. 1. Herbage mass and pasture carrying capacity

2017 ◽  
Vol 57 (3) ◽  
pp. 539 ◽  
Author(s):  
P. Beck ◽  
T. Hess ◽  
D. Hubbell ◽  
M. S. Gadberry ◽  
J. Jennings ◽  
...  
Keyword(s):  
Medicago Sativa ◽  
Trifolium Repens ◽  
Carrying Capacity ◽  
Nutritive Value ◽  
Cynodon Dactylon ◽  
Late Summer ◽  
Early Summer ◽  
Fertilisation Rate ◽  
Medicago Sativa L ◽  
Trifolium Repens L

The objective of this study was to evaluate the effects of including alfalfa (ALF, Medicago sativa L.) or a combination of white (Trifolium repens L.) and red (Trifolium pretense L.) clovers (CLVR) inter-seeded into bermudagrass (Cynodon dactylon L. Pers.) on herbage nutritive value compared with monocultures of bermudagrass fertilised with 0 (0N), 56 (56N), or 112 (112N) kg nitrogen (N)/ha over four grazing seasons. In autumn, at the end of the fourth year and in the spring before the fifth grazing season, alfalfa and clover plants were killed and the carryover N benefit of CLVR or ALF was compared with N fertilisation rates during the fifth year. Across years, N fertilisation rate increased herbage mass and carrying capacity linearly; whereas herbage production from CLVR and ALF swards was equivalent to 56N, were greater than 0N and less than 112N. Herbage mass in CLVR and ALF swards was greater than fertilised bermudagrass swards in the spring and did not differ from fertilised bermudagrass in the early summer. In late summer herbage accumulation of CLVR and ALF swards appeared to decrease, limiting the herbage mass in the legume pastures compared with 56N and 112N. Carrying capacity of CLVR and ALF swards was greater than fertilised bermudagrass in the spring and early summer, but did not differ from fertilised swards in the late summer. The N benefit of including legumes in bermudagrass swards can alleviate the reliance on synthetic N fertilisation with little overall effect on pasture carrying capacity.

scholarly journals Effects of Environmental Temperature onCapnodis tenebrionisAdult Phenology

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Carmelo Peter Bonsignore
Keyword(s):  
Late Summer ◽  
Early Summer ◽  
Adult Density ◽  
Degree Days ◽  
Continuous Increase ◽  
Climate Conditions ◽  
Average Annual Temperature ◽  
Activity Temperature ◽  
The Difference ◽  
New Generation

The phenology ofCapnodis tenebrionisadults was presented with reference to two different climate conditions. In a temperate moderate-warm climate, adult density showed two separate peaks during the year: one in early summer of the overwintering generation and one with beetles emerging in the late summer. In a warmer semiarid climate, the overwintering adults and the new generation overlapped during summer with a continuous increase of adult density. The difference in the average annual temperature between areas during the study period was almost3∘C, and, in the warmer area, the new generation ofC. tenebrionisemerged at least one month earlier. To make a prediction of adult presence, a model utilizing degree-days was developed from data collected over a five-year period. Models obtained from equations (Logistic 4-parameter,y(x)=yo+a/(1+(x/xo)b)) of each year were developed to describe the relationship between degree-day accumulation (with a minimal threshold activity temperature of14.21∘Ccalculated in the laboratory) and the cumulative percentage of adult presence. According to the overall model, the 50% of overwintering beetles occurred at 726 degree-days (Biofix: 1st March) and the emerging beetles occurred at 801 degree-days (Biofix: 1st July). The results show that a change in temperature is an important aspect that highlights the adaptability of this species.

Impact of extrafloral nectar availability and plant genotype on ant (Hymenoptera: Formicidae) visitation to quaking aspen (Salicaceae)

2015 ◽  
Vol 148 (1) ◽  
pp. 36-42 ◽  
Author(s):  
Jonathon R. Newman ◽  
Diane Wagner ◽  
Patricia Doak
Keyword(s):  
Populus Tremuloides ◽  
Late Summer ◽  
Early Summer ◽  
Quaking Aspen ◽  
Plant Genotype ◽  
Free Living ◽  
Natural Induction ◽  
Formica Fusca ◽  
Time Of Year ◽  
Nectar Availability

AbstractFor quaking aspen (Populus tremuloides Michaux; Salicaceae) the rate of extrafloral (EF) sugar secretion is increased by defoliation and decreased by drought. Although wholesale blocking of EF nectar has been shown to reduce ant (Hymenoptera: Formicidae) visitation to aspen, the effect of more subtle and realistic variations in nectar availability on ant recruitment is unknown. Working in Alaskan boreal forest (United States of America), we reduced and supplemented EF nectar availability on potted aspen ramets of three genotypes and surveyed visitation by free-living Formica fusca (Linnaeus) (Hymenoptera: Formicidae). Ants were more responsive to a subtle increase in sugar availability than to a decrease. While nectar reduction had no effect on ant visitation, nectar supplementation increased ant visitation to one aspen genotype by 70% during an early summer trial. Average ant visitation to different aspen genotypes varied during the late summer, indicating that aspen genotype can influence attractiveness to ants. We conclude that natural induction of EF secretion in response to herbivory may benefit aspen through improved ant recruitment, though the response is dependent on aspen genotype and time of year. Differences among aspen genets in attractiveness to ants could influence the relative success of genotypes, especially in settings in which aspen regenerates from seed.

scholarly journals Diatoms as a paleoproductivity proxy in the NW Iberian coastal upwelling system (NE Atlantic)

2017 ◽  
Vol 14 (5) ◽  
pp. 1165-1179 ◽  
Author(s):  
Diana Zúñiga ◽  
Celia Santos ◽  
María Froján ◽  
Emilia Salgueiro ◽  
Marta M. Rufino ◽  
...  
Keyword(s):  
Water Column ◽  
Surface Sediment ◽  
Sediment Trap ◽  
Coastal Upwelling ◽  
Late Summer ◽  
Early Summer ◽  
Marine Diatom ◽  
Photic Zone ◽  
Upwelling System ◽  
Water Column Stratification

Abstract. The objective of the current work is to improve our understanding of how water column diatom's abundance and assemblage composition is seasonally transferred from the photic zone to seafloor sediments. To address this, we used a dataset derived from water column, sediment trap and surface sediment samples recovered in the NW Iberian coastal upwelling system. Diatom fluxes (2.2 (±5.6) 106 valves m−2 d−1) represented the majority of the siliceous microorganisms sinking out from the photic zone during all studied years and showed seasonal variability. Contrasting results between water column and sediment trap diatom abundances were found during downwelling periods, as shown by the unexpectedly high diatom export signals when diatom-derived primary production achieved their minimum levels. They were principally related to surface sediment remobilization and intense Minho and Douro river discharge that constitute an additional source of particulate matter to the inner continental shelf. In fact, contributions of allochthonous particles to the sinking material were confirmed by the significant increase of both benthic and freshwater diatoms in the sediment trap assemblage. In contrast, we found that most of the living diatom species blooming during highly productive upwelling periods were dissolved during sinking, and only those resistant to dissolution and the Chaetoceros and Leptocylindrus spp. resting spores were susceptible to being exported and buried. Furthermore, Chaetoceros spp. dominate during spring–early summer, when persistent northerly winds lead to the upwelling of nutrient-rich waters on the shelf, while Leptocylindrus spp. appear associated with late-summer upwelling relaxation, characterized by water column stratification and nutrient depletion. These findings evidence that the contributions of these diatom genera to the sediment's total marine diatom assemblage should allow for the reconstruction of different past upwelling regimes.

scholarly journals Spatial and temporal distribution of phytoplankton in Lake Skadar

2012 ◽  
Vol 64 (2) ◽  
pp. 585-595 ◽  
Author(s):  
Jelena Rakocevic
Keyword(s):  
Spatial Heterogeneity ◽  
Phytoplankton Community ◽  
General Pattern ◽  
Seasonal Succession ◽  
Temporal Distribution ◽  
Late Summer ◽  
Early Summer ◽  
Quantitative Composition ◽  
Autumn And Winter ◽  
Lake Skadar

Phytoplankton seasonal succession and spatial heterogeneity were studied in Lake Skadar from February to December 2004. A total of 167 taxa from 6 algal divisions were observed, with Bacillariophyta being best represented (52.8%). The general pattern of phytoplankton seasonal succession in Lake Skadar was: Bacillariophyta in the spring, Chlorophyta in early summer, Cyanobacteria and Chlorophyta in late summer and Bacillariophyta and Chlorophyta in autumn and winter. Distinct spatial heterogeneity was observed. The central, open part of the lake (pelagic zone) was characterized by dominant euplanktonic species, mostly diatoms, whereas the western and northwestern parts (more isolated and shallower) had higher abundance of greens and blue-greens and a higher percentage of resuspended benthic-epiphytic forms in the phytoplankton community. Comparison with former phytoplankton data showed distinct differences in terms of the qualitative and quantitative composition of the phytoplankton community of Lake Skadar, which indicates lake deterioration.

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