Effects of simulated green turtle regrazing on seagrass abundance, growth and nutritional status in Moreton Bay, south-east Queensland, Australia

2007 ◽  
Vol 58 (5) ◽  
pp. 492 ◽  
Author(s):  
Marianne Kuiper-Linley ◽  
Craig R. Johnson ◽  
Janet M. Lanyon
Keyword(s):  
Starch Content ◽  
Leaf Size ◽  
Water Soluble ◽  
Leaf Biomass ◽  
Soluble Carbohydrate ◽  
Seagrass Species ◽  
Green Turtles ◽  
Moreton Bay ◽  
Halophila Ovalis ◽  
Seagrass Biomass

In some parts of their range, green turtles maintain grazing plots in seagrass beds by regular regrazing. The effects of simulated repeated grazing on subtropical seagrasses in Moreton Bay, Australia were investigated in a manipulative experiment over summer. Three seagrass species were subjected to two different clipping frequencies (simulating turtle cropping) and compared with unclipped controls over a 3.5-month summer period for the effects on seagrass biomass, leaf size and regrowth rates and water-soluble carbohydrate (WSC) and starch content. The order of the seagrass species’ relative tolerance to simulated grazing was Halophila ovalis > Zostera capricorni > Cymodocea serrulata. Frequent regrazing of the green turtle’s preferred seagrass, H. ovalis, resulted in an increase in leaf regrowth rate so that standing biomass of leaves and total plant material was maintained, suggesting an increase in productivity. Furthermore, whole-plant concentrations of WSC increased significantly in clipped H. ovalis plants relative to unclipped controls. In contrast, leaf biomass of the seagrass species less preferred by turtles, Z. capricorni and C. serrulata, decreased in response to repeated leaf removal relative to controls, despite maintenance of leaf regrowth rates. C. serrulata responded to repeated clipping with a reduction in leaf size and a decrease in rhizome WSC concentration. Z. capricorni also produced fewer and smaller new leaves. The ability of the preferred species, H. ovalis, to increase production of nutrient-rich standing crop in response to regrazing has major implications for green turtles and other seagrass grazers.

Distribution of seagrasses and associated juvenile commercial penaeid prawns in north-eastern Queensland waters

1987 ◽  
Vol 38 (1) ◽  
pp. 103 ◽  
Author(s):  
RG Coles ◽  
WJ Lee Long ◽  
BA Squire ◽  
LC Squire ◽  
JM Bibby
Keyword(s):  
Summer Rainfall ◽  
Dry Weight ◽  
Seagrass Beds ◽  
Seagrass Species ◽  
Thalassia Hemprichii ◽  
Halophila Ovalis ◽  
Penaeid Prawn ◽  
Seagrass Biomass ◽  
Almost All ◽  
The Tropics

Thirteen species of seagrass and six species of juvenile penaeid prawn of commercial importance were found in seagrass beds in waters between Cape York and Cairns. The pioneering seagrass species, Halodule uninemis (Forsk.) Aschers, and Halophila ovalis (R. Br.) Hook. f., were present in almost all coastal areas. Two seagrass species often dominant in the tropics, Enhalus acoroides (L.f.) Royle and Thalassia hemprichii (Ehrenb.) Aschers., were uncommon. This is likely to have resulted from environmental stress during periods of reduced salinity and high turbidity associated with seasonal summer rainfall. Halophila decipiens Ostenfeld was the only species found in depths > 11 m. Three depth-related zones of species are described. With the exception of E. aroroides, most seagrasses were <20 cm in height. Seagrass biomass was greatest in 2-6 m of water. Maximum dry weight of above-ground plant material and maximum leaf area from a square metre of bottom was 99.6 g and 4.5 m2, respectively, at the Flinders Group of islands. The distribution of prawns and seagrasses did not show a trend with latitude. Penaeus esculentus Haswell and Metapenaeus endeavouri (Schmitt), the most numerous penaeid prawn species in commercial trawl catches, were also the most numerous juvenile prawns in seagrass beds. Juvenile P. longistylus Kubo were found for the first time in northern Queensland seagrass beds. Although juveniles of this species appeared to occupy only a narrow habitat range, these habitats were found in coastal bays, in estuaries and on coral-reef platforms where conditions were suitable. Size-class data suggest that reef prawns and coastal prawns are parts of the same population. The timing of the life cycle of the major commercial prawn species differed from that found previously in the Gulf of Carpentaria.

Seagrass characterization on the southern Pacific coast of Costa Rica: history, vegetation, and environment

2020 ◽  
Vol 63 (5) ◽  
pp. 429-438
Author(s):  
Jimena Samper-Villarreal ◽  
Jorge Cortés
Keyword(s):  
Costa Rica ◽  
Pacific Coast ◽  
Management Strategies ◽  
Shoot Density ◽  
Nutrient Concentrations ◽  
Seagrass Habitat ◽  
Spatial And Temporal Variability ◽  
Seagrass Species ◽  
Seagrass Biomass ◽  
Herbarium Collections

AbstractSeagrass conservation and management requires scientific understanding of spatial and temporal variability, information that is currently limited for the Eastern Tropical Pacific (ETP). Here, we analysed seagrass presence based on previous reports, herbarium collections and stakeholder knowledge, combined with field characterization in Golfo Dulce, southern Pacific coast of Costa Rica. Seagrasses were found at multiple locations along a narrow border close to shore and in up to 6 m depth within Golfo Dulce, dating back to 1969. Two seagrass species were found, Halophila baillonii and Halodule beaudettei. Seagrass biomass values for Golfo Dulce (12.0 ± 8.5 g DW m−2) were lower and water nutrient concentrations were higher than previously reported in the gulf. Shoot density (1513 ± 767 shoots m−2) was similar to previous reports. Stable isotope values in seagrass were −11.3 ± 1.0‰ δ13C and 1.2 ± 0.9‰ δ15N; while those in sediments were −26.1 ± 1.3 and 2.5 ± 0.9‰. In Golfo Dulce, isotopic values of both seagrass species do not overlap with other known primary producers. Management strategies should aim to minimize known seagrass stressors, protect potential seagrass habitat, and take into account the dynamic life strategies of the two seagrass species found.

Defoliation frequency and cultivar effects on the storage and utilisation of stolon and root reserves in white clover

2000 ◽  
Vol 51 (8) ◽  
pp. 1039 ◽  
Author(s):  
A. R. Lawson ◽  
K. B. Kelly ◽  
P. W. G. Sale
Keyword(s):  
White Clover ◽  
Plant Size ◽  
Water Soluble ◽  
Cultivar Differences ◽  
Soluble Carbohydrate ◽  
Leaf Production ◽  
Plant Weight ◽  
Stolon Length ◽  
Defoliation Frequency ◽  
Leaf Appearance

The effects of defoliation frequency (2 or 6 defoliations over a 91-day period) on the reserve status and growth rate of 2 white clover cultivars, cvv. Irrigation (medium-leafed) and Haifa (large-leafed), were examined over the final 42 days of the defoliation treatments. The clover plants consisted of single stolons growing in a sand/scoria mix in an unheated glasshouse, and were fertilised weekly with a solution containing essential nutrients excluding nitrogen. More frequent defoliation reduced the leaf appearance rate, stolon elongation rate, and plant size, and increased stolon death, with all of these effects being less pronounced in Irrigation than in Haifa (18% v. 30%, 60% v. 80%, and 23% v 34%, respectively, for leaf appearance rates, stolon elongation rates, and the proportion of stolon length that died). With infrequent defoliation, the combined utilisation of starch and water-soluble carbohydrate (WSC) reserves in the first 14 days after defoliation was equivalent to 15% of the plant weight at defoliation, and to 95% of the new leaf produced during that period. Frequent defoliation reduced the reserve content and remobilisation less in Irrigation than in Haifa, with the combined mass of remobilised starch and WSC over the first 14 days after defoliation being 2.9% and 2.0% of the plant weight at defoliation, and 29% and 19% of leaf production over that period, for Irrigation and Haifa, respectively. The greater reserve mobilisation in Irrigation than in Haifa plants under frequent defoliation probably contributed to their higher growth rates and reduced stolon death. These cultivar differences with frequent defoliation suggest that Irrigation is more suited to frequent defoliation than Haifa.

The assessment of herbage legume varieties. II. In vitro digestibility, water soluble carbohydrate, crude protein and mineral content of primary growth of clover and lucerne

1966 ◽  
Vol 66 (3) ◽  
pp. 351-357 ◽  
Author(s):  
W. Ellis Davies ◽  
G. ap Griffith ◽  
A. Ellington
Keyword(s):  
White Clover ◽  
Crude Protein ◽  
Dry Matter ◽  
Red Clover ◽  
Water Soluble ◽  
Soluble Carbohydrates ◽  
Soluble Carbohydrate ◽  
In Vitro Digestibility ◽  
Primary Growth

The primary growth of eight varieties of three species–white clover (3), red clover (4) and lucerne (1)–was sampled at fortnightly intervals and the percentage dry matter, in vitro digestibility, crude protein, water soluble carbohydrates, P, Ca, K, Na and Mg were determined.Differences between species were nearly always significant and the general order of merit was white clover, red clover and lucerne. The exceptions were for dry-matter percentage where this order was reversed, and red clover had the lowest Na and highest Mg content.

Characterisation of the WSC fraction of six species of temperate pasture grass

2004 ◽  
Vol 32 ◽  
pp. 247-248
Author(s):  
J. C. Ince ◽  
A. C. Longland ◽  
A. J. Cairns ◽  
M. Moore–Colyer
Keyword(s):  
Perennial Ryegrass ◽  
Water Soluble ◽  
Italian Ryegrass ◽  
Soluble Carbohydrate ◽  
Meadow Fescue ◽  
Pasture Grass ◽  
Pasture Grasses ◽  
Optimal Health ◽  
Water Soluble Carbohydrate ◽  
Field Plots

The carbohydrate (CHO) fraction of pasture grasses is a major source of energy for many domestic herbivores. However, the amounts, and types, of the water–soluble carbohydrate (WSC) fraction (i.e. glucose, fructose, sucrose, and polymers of sucrose and fructose, the fructans) present in such grasses, varies with species and environmental conditions. As the WSC constitute a highly digestible, energy yielding fraction of grasses, it is important to be able to measure their levels in a sward so that the diets of pastured animals may be designed to elicit optimal health and productivity. The aim of this study was to characterise the WSC profile of six UK pasture grasses, and to develop a technique for extracting the fructan portion of the WSC.Six species of UK pasture grasses [Cocksfoot (C), Timothy (T), Meadow Fescue (M), Italian Ryegrass (IR), Perennial Ryegrass (PR) and Hybrid Ryegrass (HR)] were grown in experimental field plots at IGER.

scholarly journals The effect of drying and ensiling grass on its digestion in sheep

1971 ◽  
Vol 26 (2) ◽  
pp. 123-134 ◽  
Author(s):  
D. E. Beever ◽  
D. J. Thomson ◽  
E. Pfeffer ◽  
D. G. Armstrong
Keyword(s):  
Small Intestine ◽  
Digestive Tract ◽  
Terminal Ileum ◽  
Water Soluble ◽  
Soluble Carbohydrate ◽  
Proximal Duodenum ◽  
Fresh Frozen ◽  
Gross Energy ◽  
Water Soluble Carbohydrate

1. The effect of drying and ensiling ryegrass on the site of digestion of the energy andcarbohydrate fractions was studied in sheep fitted with rumen cannulas and re-entrant can-nulas in the proximal duodenum and terminal ileum.2. The sheep were given fresh (frozen) grass, dried grass, wilted and unwilted silage pre-pared from herbage harvested from the same sward. The grass diets were offered twice dailyto each animal and paper impregnated with chromium sesquioxide was administered twicedaily into the rumen. Twenty-four hour collections of duodenal and ileal digesta, adjusted togive 100 yo recovery of Cr2O3, were analysed to determine the extent of digestion in the fore-stomachs, the small intestine and the caecum and colon.3. Total digestibility of the gross energy was similar for the fresh grass, dried grass andwilted silage diets (67·4,68·1 and67·5 %)but higher for the unwilted silage (72·0 %, P < 0·01).There was an increased flow of energy into the small intestine when the sheep were given driedgrass and unwilted silage. The proportion of the apparently digested energy lost within thesmall intestine was greater when the dried grass was given (302 yo) than when the fresh grasswas given (23·6 yo).4. Drying or ensiling of wilted material affected digestion neither in the entire alimentarytract nor in the different sections of the tract, of some carbohydrate fractions. About 97 yo ofthe digested water-soluble carbohydrate, over 90 yo of the digested cellulose and over 70 yo ofthe digested hemicellulose were digested before reaching the small intestine. The increasedamount of energy entering the duodenum of the sheep given the dried grass was notaccounted for by changes in the fate of these carbohydrate fractions in the digestive tract. Withunwilted silage, digestibilities of the cellulose and hemicellulose fractions were higher, andlower proportions of the digested carbohydrates were lost before the small intestine.

scholarly journals Morphological and Physiological Responses of Seashore Paspalum and Bermudagrass to Waterlogging Stress

2019 ◽  
Vol 144 (5) ◽  
pp. 305-313
Author(s):  
Bo Xiao ◽  
David Jespersen
Keyword(s):  
Lipid Peroxidation ◽  
Root Respiration ◽  
Morphological Changes ◽  
Physiological Responses ◽  
Specific Root Length ◽  
Water Soluble ◽  
Soluble Carbohydrate ◽  
Seashore Paspalum ◽  
Waterlogging Stress ◽  
Turf Quality

Turfgrasses have varying tolerance to waterlogging conditions. The objective of this study was to identify important root traits and physiological responses to waterlogging stress in seashore paspalum (Paspalum vaginatum) and bermudagrass (Cynodon sp.). After being exposed to waterlogging conditions for 28 days, turf quality, leaf photosynthesis, transpiration rate, stomatal conductance (gS), and root fresh weight were significantly decreased in bermudagrass, and root lipid peroxidation was significantly increased. However, seashore paspalum was found to be more tolerant to waterlogging conditions and changes in turf quality, photosynthesis, or lipid peroxidation were not seen. The waterlogging treatments increased specific root length (SRL), surface area, and volume and decreased root respiration and diameter to a greater extent in seashore paspalum compared with bermudagrass. Under waterlogging conditions, root aerenchyma formation was found in both seashore paspalum and bermudagrass, but to a greater extent in seashore paspalum. Both grasses exhibited significant increases in root water-soluble carbohydrate (WSC) but to a lesser extent in seashore paspalum than in bermudagrass. Shoot WSC remained unchanged in seashore paspalum but was significantly increased in bermudagrass. These results indicate greater root morphological changes such as root volume, SRL, and root porosity, as well as lower root respiration may be important contributors to waterlogging tolerance for seashore paspalum.

Sign in / Sign up

Export Citation Format

Share Document