Humic acids extracted from the sediment of Cochin inshore areas exhibited impairment of mercury toxicity to marine algae maintained in Walne's medium under laboratory conditions. Cultures of marine micro alga /50chrysis galbana contaminated with sublethal concentration of 10 ppb of inorganic mercury and 10 ppm humic acids registered 18%, 21 % and 37% increase in oxygen production for two, four and six hours incubation in light respectively, when compared to the controls. Similarly the daily growth rate of seaweed Ulva lactuca registered 26% increase over the control when the seaweed was maintained in medium containing 30 ppb Hg and 30 ppm humic acids.
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Effect of light intensit}-on the saturated phtosynthcsis was studied in three different species of Graci/aria. Photosynthetic oxygen evolution reached saturation in the range of 15 to 30 ~ Elm1/sec. However, the saturation in G. crassa was observed at low intensity than G. edulis and G. corticota. The photosynthetic activity was found to be maximum in O. corticoiD. I~C02 uptake also showed maximum carbon fixed per unit fresh weight in G corlicala i.e., 21 .3 m mole I g. Fw I h as compared to 18.1 m mole I g. Fw I h in G. edulis and 17.9 m mole I g. Fw I h in G. corlicala.
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Phlorotannins have been reported to have positive effects on pig health, including improved gut health and digestibility. In this study, we investigate the effect of phenolics found in two brown seaweeds, Ascophyllum nodosum and Fucus serratus, on in vitro dry matter digestibility of seaweeds and commercial pig feed. Phlorotannin extracts and whole seaweeds were supplemented into pig feed to test their effect on digestibility. Solid-phase extraction was used to purify the phenolics to phlorotannins. The results showed a slight decrease in the digestibility of pig feed that was found to be significant when phlorotannin extracts were added from either seaweed. However, when whole A. nodosum was added to the pig feed, the effect on digestibility was less pronounced. Specifically, no significant difference in digestibility was observed at inclusion rates up to 5%, and thereafter results varied. A difference in digestibility was also observed in the same species at the same inclusion rate, collected from different seasons. This suggests that other compounds, e.g., polysaccharides, are having an effect on digestibility when whole seaweeds are supplemented to animal feed. This research has also highlighted the need to base supplementation on phenolic concentration as opposed to a standardised percentage inclusion of seaweeds to ensure that digestibility is not adversely affected.
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Seaweeds are the only source for the production of phytochemicals such as agar, carrageenan and alginates which are widely used in many industries mostly as gelling, stabilizing and thickening agents They are also used as human food, animal feed and manure.
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The effect of repeated harvesting on the growth of Gelidiella acerosa was studied for one year from August '87 to July '88 and Gracilaria corticata var. corticata for two years from July '87 to May '89. The growth of these agar yielding seaweeds depended on the harvesting season and the interval between successive harvests. The regrowth of these red algae continues as long as the basal rhizomatous portion is intact with the substratum. Hence harvest should be done by pruning the plants leaving the basal portions instead of plucking the whole plants. The commercial exploitation of G. acerosa should be made only during April to July and G. corticata var. corticata during April to June and September to November giving ample interval for their regrowth to harvestable size.
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Studies were made on thk effect of repeated harvesting on the growth of Sargassam cristaefolium, S. ilicifolium, S. polycystum, S. wightii and Turbinaria conoides occurring at Mandapam coast for a period of 2 years during June 1986 to November 1988. The growth of these algin yielding seaweeds depended on the period of harvesting and interval between one harvest and next. The maximum standing crop with plants of maximum stature was found during the period September to January in these brown algae. An interval of 7 months is required for the regrowth of these plants to harvestable size and the suitable season for commercial exploitation of these algae is September to January.
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The study was carried out in a private nursery in Al-Qasim district located in Babil governorate in the period from 1/9/2018 to 1/9/2019 to study the effect of spraying with marine algae extract (Agazone) and cytokinin spray (CPPU) on the growth of local sour lemon grafted on the origin of Citrus aurantium. The experiment was carried out according to the design of the complete random sectors and three replicates, where the experiment included spraying four concentrations of seaweed extract (Agazone) 0, 3, 6, 9ml /L-1 and four levels of spray regulator growth (CPPU) 0,2,4,8 mg/L-1. The results showed a significant effect in all the studied traits, especially the treatment of spraying with Agazone algae extract at the concentration of 9 mL/-1 and spraying with growth regulator CPPU at the concentration of 8 mg/ L-1 as it achieved a significant increase in seedling height, number of leaves, area of leaves, increase plant stem diameter rate. The stem was 78.75 cm, 83.42 cm, 63.83 leaves. Seedlings-1, 65.33 leaves. Seedlings-1, 1401.25 creamy 2. Seedlings-1, 1633.56 creamy 2. Seedlings-1, 1.65 mm, 1.44 mm as well as leaf content of chlorophyll and nitrogen were 47.89 SPAD, 47.98 SPAD, 2.47%, 2.44% respectively for both study factors.
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Heavy metals and organic pollutants are introduced into the aquatic ecosystems as a result of human activities involving agricultural uses, industrial discharges, domestic effluents and agricultural runoff. These contaminants such as herbicides, pesticides, nitrogen and phosphate fertilizers, heavy metals... etc., have negative impacts on both the stability of the natural aquatic environment (intensification of eutrophication, contamination and disappearance of certain animal and plant species...) and can cause adverse effects on human health. Recently there has been an increasing interest in using seaweeds for water quality assessment and for removal of heavy metals and organic pollutants. In this review, we will discuss the use of macroalgae as bioindicators for monitoring and protecting aquatic environments and different mechanisms used by these seaweeds for metal accumulation and detoxification.
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In this study, a brown macroalgae species, Saccharina latissima, processed to increase its protein concentration, and a red macroalgae species, Porphyra spp., were used to evaluate their in vivo digestibility, rumen fermentation and blood amino acid concentrations. Four castrated rams were used, whose diets were supplemented with a protein-rich fraction of S. latissima, a commercial Porphyra spp. and soybean meal (SBM). Our results show that the protein digestibility of a diet with S. latissima extract was lower (0.55) than those with Porphyra spp. (0.64) and SBM (0.66). In spite of the higher nitrogen (N) intake of diets containing Porphyra spp. and SBM (20.9 and 19.8 g N/day, respectively) than that with S. latissima (18.6 g N/day), the ratio of N excreted in faeces to total N intake was significantly higher in the diet with S. latissima than those with Porphyra spp. and SBM. This reflects that the utilization of protein in S. latissima was impaired, possibly due to reduced microbial activity. The latter statement is corroborated by lower volatile fatty acid composition (25.6, 54.8 and 100 mmol/l for S. latissima, Porphyra spp. and SBM, respectively) and a non-significant tendency for lower ammonia concentration observed in diets with
S. latissima and Porphyra spp. compared to SBM. It is important to note that the S. latissima used in this trial was rinsed during processing to remove salt. This process potentially also removes other water-soluble compounds, such as free amino acids, and may have increased the relative fraction of protein resistant to rumen degradation and intestinal absorption. Furthermore, the phlorotannins present in macroalgae may have formed complexes with protein and fibre, further limiting their degradability in rumen and absorption in small intestines. We recommend that further studies explore the extent to which processing of macroalgae affects its nutritive properties and rumen degradability, in addition to studies to measure the intestinal absorption of these macroalgae species.
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The photosynthetic performance of two species of Meristotheca (Solieriaceae, Rhodophyta), M. coacta and M. papulosa, was investigated under a variety of temperature and light conditions to derive basic information regarding their physiology. A pulse amplitude modulated-chlorophyll fluorometer (Imaging-PAM) was used to generate rapid light curves (RLCs) to provide the relative electron transport rates (rETR) over 21 levels of photosynthetic active radiation (PAR), ranging from 0 to 1,078μmol photons m-2 s-1 at 14 temperatures (i.e., from 8 to 34℃). The initial slope (α), photoinhibition (β) and coefficient (γ) was calculated by fitting the RLCs to a nonlinear model of the form rETR=γ(1-exp(-α･PAR/γ)) (exp(-β･PAR/γ)) using a two-level hierarchical Bayesian model. Both species required temperatures ranging from 18 to 28℃ to maintain optimal photosynthetic activity, as revealed by the estimated model parameters. The optimal PAR (PARopt) increased with increasing temperature. Meristotheca coacta and M. papulosa can be considered well-adapted to the current natural light and temperature conditions of southern Kyushu, Japan. Finding in this study should be useful to the design and manage mariculture programs to conserve the natural resources.
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Marine Agronomy Group, CAFNRM, UH-Hilo
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