Effects of salinity,light intensity and sediment on growth,pigments, agar production and reproduction in Gracilaria tenuistipitata from Songkhla Lagoon in Thailand

The effects of salinity, light intensity and sediment on Gracilaria tenuistipitata C.F. Chang & B.M. Xia on growth, pigments, agar production, and net photosynthesis rate were examined in the laboratory under varying conditions of salinity (0, 25 and 33 psu), light intensity (150, 400, 700 and 1000 µmol photons m^?2 s^?1) and sediment (0, 0.67 and 2.28 mg L^?1). These conditions simulated field conditions, to gain some understanding of the best conditions for cultivation of G. tenuistipitata. The highest growth rate was at 25 psu, 700 µmol photons m^?2 s^?1 with no sediments, that provided a 6.7% increase in weight gain. The highest agar production (24.8 ± 3.0 %DW) was at 25 psu, 150–400 µmol photons m^?2 s^?1 and no sediment. The highest pigment contents were phycoerythrin (0.8 ± 0.5 mg g^?1FW) and phycocyanin (0.34 ± 0.05 mg g^?1 FW) produced in low light conditions, at 150 µmol photons m^?2 s^?1. The highest photosynthesis rate was 161.3 ± 32.7 mg O₂ g^?1 DW h^?1 in 25 psu, 400 µmol photons m^?2 s^?1 without sediment in the short period of cultivation, (3 days) and 60.3 ± 6.7 mg O₂ g^?1 DW h^?1 in 25 psu, 700 µmol photons m^?2 s^?1 without sediment in the long period of cultivation (20 days). The results indicated that salinity was the most crucial factor affecting G. tenuistipitata growth and production. This would help to promote the cultivation of Gracilaria cultivation back into the lagoon using these now determined baseline conditions. Extrapolation of the results from the laboratory study to field conditions indicated that it was possible to obtain two crops of Gracilaria a year in the lagoon, with good yields of agar, from mid‐January to the end of April (dry season), and from mid‐July to the end of September (first rainy season) when provided sediment was restricted.     

Preparation of superior quality products from two Indian agarophytes

The effect of alkali pre-treatments on the properties of agar obtained from Gelidiella acerosa and Gelidium pusillum growing along the West and South coast of India was studied in order to evaluate its potential for industrial use. Agar samples were extracted by hot water extraction and termed native agar, and alkali pre-treatment was carried out with various NaOH concentrations e.g. 4%, 6%, 8%, 10% and 15%, to optimise the alkali concentration for preparation of alkali-treated agar. Gelidiella acerosa and Gelidium pusillum produced superior quality agar polymers having greater gel strengths 2,000 ± 50 and 1,400 ± 50 g cm⁻² and lower sulphate contents ≤0.30% and ≤0.50%, respectively, as opposed the low gel strength and high sulphate content agars reported in the literature. Furthermore, the physicochemical properties of agars were identical with the commercially available agars. The results of this study revealed that Indian agarophytes may be used for production of superior quality agar and agaroses, which may be used for food and biological applications.     

Seasonal agar yield and quality inGelidium canariensis (Grunow) Seoane-Camba (Gelidiales,Rhodophyta) from Gran Canaria,Spain

The seasonal effects on yield and gel properties ofGelidium canariensis agar were investigated at two intertidal populations at the northern coast of Gran Canaria. Physical and rheological properties were measured in 1.5% w/v solutions after treatment with alkali. No significant differences were found on agar characteristics between the two sites studied. The highest yields were obtained during summer with a maximum in June (27.8%) and minimum during late autumn and winter (18–18.6%). Overall quality was highest in winter (November–January), when gel strength peaked above 850 g cm^–2. The results showed an agar of industrial quality.     

Karyology and agar analysis of the agarophyteGelidiella acerosa (Forsskål) Feldmannet Hamel from the Philippines

Microspectrophotometry with the DNA-localizing fluorochrome DAPI demonstrated ploidy level differences in tetrasporophytic and presumptive gametophytic phases ofGelidiella acerosa from the Philippines. Comparison of mean nuclear DNA (I _f ) values to chicken erythrocytes (RBC) resulted in an estimate of 0.32 pg/2 C genome. Karyological studies with aceto-orcein revealed a chromosome complement of six bivalents during diakinesis of tetrasporocytes. The agar yield ranges from 13–24% dry weight, depending on the method of extraction. Agar extraction in 1 N NaOH resulted in an increased gel strength of 189 g cm^–2 at 1.5% concentration. Infrared spectroscopy indicated a relatively high sulfate content in native agar. The low (61 °) melting temperature is indicative of high sulfation and small molecular size.     

Seasonal variation in the physical properties of agar and biomass of Gracilaria sp. (chorda type) from Tosa Bay,southern Japan

Plants of Gracilaria sp.(chorda type), which grow along the coast of Uranouchi Inlet in Tosa Bay, southern Japan, showed the highest biomass in the summer (26 °C to 31 °C) and spring season (15.1 °C to 24.9 °C). Maximum biomass was 6952 g m^–2 in July, but gradually decreased in the autumn (30.5 °C in September to 20 °C in November) and winter (19.5 °C in December to 14.9 °C in February). Variation in yields and gel strength of the agars, were shown to depend on the time in the season. After alkali treatment (5% NaOH, 2 h) at three different temperatures (70, 80, and 90 °C), the agars showed gel strengths essentially that of commercial grade agars, with the best gel obtained at 80 °C. Maximum gel strength (1455 g cm^–2 of 1.5% agar gel) occurred in winter when the biomass and agar yield were low. Minimum gel strength was in spring. Gel strength was inversely correlated with agar yield, but was positively correlated with apparent viscosity. Maximum viscosity was 40 cP. in December. Gelling temperatures, pH of 1.5% agar gel, and moisture content in agars showed little variation.     

Effect of epiphyte infection on physical and chemical properties of carrageenan produced by Kappaphycus alvarezii Doty (Soliericeae,Gigartinales, Rhodophyta)

Epiphytism of filamentous red algae is a serious problem in Kappaphycus farms in the Philippines, Indonesia, Malaysia, and Tanzania. The causative organism of epiphyte outbreak has been identified as Neosiphonia apiculata (Hollenberg) Masuda and Kogame, but its actual effect on carrageenan quality has not yet been established. Therefore, yield and quality of carrageenan from healthy and infected specimens were examined. Infected specimens showed 20.5?±?2.5 % DW lower carrageenan yield compared with the healthy seaweed (65.5?±?4.2 % DW). Infected specimens also had a higher phenolic and fatty acid content, compared with healthy specimens. The carrageenan from the infected seaweed showed 74.5?±?2.8 % lower viscosity, 52.6?±?3.6 % lower gel strength, 22.9?±?1.5 % higher syneresis, and 5 °C higher melting temperature as compared with carrageenan from healthy specimens. FTIR and ¹³C-NMR analysis of carrageenan from infected seaweed did not show any differences in their functionality or carbon atom chemical shift as compared with healthy and standard k-carrageenan. However, size exclusion chromatography showed the infected carrageenan molecular size to be 80 kDa as compared with 800 kDa for the healthy and standard k-carrageenan. These findings prove that infection of Kappaphycus by the filamentous red algae epiphyte, N. apiculata, reduces carrageenan molecular size and affects the physical properties of the carrageenan.     

Evaluation of growth rate and semi‐refined carrageenan properties of tissue‐cultured Kappaphycus alvarezii (Rhodophyta,Gigartinales)

This study aimed to evaluate and compare the quality of κ‐carrageenan obtained from tissue‐cultured and field‐cultured Kappaphycus alvarezii. Carrageenan properties including yield, viscosity, gel strength and sulfate content were studied. After 60 days of cultivation, tissue‐cultured K. alvarezii showed a higher growth rate (6.3 ± 0.01% day^?1) than field‐cultured seedlings (3.4 ± 0.3% day^?1). The obtained carrageenan yield from tissue‐cultured (67.3 ± 16.4%) was higher than field‐cultured K. alvarezii (51.5 ± 21.0%). Gel viscosity of carrageenans from tissue‐cultured K. alvarezii (1280.0 ± 25.0 cP) was found significantly higher than field‐cultured samples (87.8 ± 20.9 cP). The 1.5% gel solution of tissue‐cultured and field‐cultured K. alvarezii exhibited gel strengths of 703.5 ± 14.1 and 288.3 ± 19.3 g cm^?2, respectively. The average sulfate content of carrageenans was found to be significantly different between tissue‐cultured and field‐cultured K. alvarezii with 34.2 ± 10.9 and 7.5 ± 6.7%, respectively. Tissue culture is recommended to produce high quality seedlings by providing optimized culture conditions to the seaweed. This approach can serve as an alternative way to solve the seedling shortage problems currently faced by the seaweed industry.     

Optimization of agar extraction from local seaweed species,Gracilaria salicornia in Tanzania

This study aimed to develop agar extraction protocols for Gracilaria salicornia from Tanzania and investigate its physico‐chemical characteristics. A 3³ factorial experimental design was used in the extraction of agar whereby three independent variables of NaOH concentration (10, 20 and 30% w/v), alkali pre‐treatment duration (0.5, 1 and 2 h) and extraction temperatures (115, 120 and 125°C) were used to determine the optimum conditions for production of high‐quality agar. Agar yield, gel strength, sulfate content, gelling and melting temperatures were evaluated as dependent variables. The optimal condition was observed at 30% NaOH concentration, 2 h alkali pre‐treatment duration and 120°C extraction temperature. The yield, gel strength, sulfate content, gelling and melting temperatures of the agar obtained under these conditions were 26.9 ± 0.7%, 510.3 ± 16.2 g cm^?2, 0.29 ± 0.04%, 39.3°C and 88.4°C, respectively. These properties are very close to that of imported commercial agar. It was concluded that the local agar is capable of replacing imported agar for most general purposes. This offers a new possibility of using quality local agar in place of commercial agar.     

PHOSPHORUS AND NITROGEN NUTRITION IN CHONDRUS CRISPUS (RHODOPHYTA): EFFECTS ON TOTAL PHOSPHORUS AND NITROGEN CONTENT,CARRAGEENAN PRODUCTION,AND PHOTOSYNTHETIC PIGMENTS AND METABOLISM1

The existence of a phenomenon in phosphorus (P) nutrition comparable to the “Neish effect” in nitrogen (N) nutrition (an inverse relation between seawater N enrichment and carrageenan content) was investigated in the temperate red alga Chondrus crispus Stackhouse. Plants were preconditioned for 17 d and then cultured under varying enrichments of P (0, 3, 6, 10, 15 μM P·wk^?1) and a constant N enrichment (53.5 μM N·wk^?1) for 5 wk. Tissue total P, tissue total N, and carrageenan contents were then determined. Identical experiments were performed using C. crispus collected during the fall, winter, spring, and summer seasons. The procedure was repeated using material collected during the following fall season and cultured under constant P (6 μM P·wk^?1) and varying N enrichments (0, 3, 6, 10, 25 μM N·wk^?1). In the fall (P) experiment, carrageenan content was the highest [53.1 ± 0.3% DW (dry weight)], and tissue total P content was the lowest (1.71 ± 0.27 mg P·g DW^?1) in plants that received no P enrichment. Carrageenan content was stable (46.1 ± 1.8% DW) for plants given enrichments of 3 μM P·wk^?1 and greater. Thus, a decrease in carrageenan content, concomitant with an increase in tissue total P content, was observed, but only at tissue total P levels below 2 mg P·g DW^?1. As these levels were always higher than 2 mg P·g DW^?1 in the winter, spring, and summer experiments, carrageenan content remained constant within each season at 46.2 ± 1.3, 43.1 m 0.7, and 44.5 ± 0.6% DW, respectively. Nitrogen enrichment of plants collected in the fall did not affect carrageenan content, which was stable at 49.3 ± 0.9% DW. When these plants were compared with those of the previous fall experiment (6 μM P·wk^?1 and 53.5 μM N·wk^?1), a slight increase in carrageenan content was noted. Thus, at sufficiently high concentration, N also decreased carrageenan content in C. crispus. Phosphorus nutrition had no significant effect on photosynthesis versus irradiance parameters (P_max, α, R_d, I_c, and I_k), the contents of the photosynthetic pigments chlorophyll-a, phycoerythrin (PE), phycocyanin (PC), and allophycocyanin (APC), and the ratios PE:APC and PC:APC. In contrast, N nutrition affected both P_maxand the photosynthetic pigment contents. The data indicate that N limitation reduces the number of phycobilisomes but not their size. The greater reduction in phycobiliprotein than chlorophyll-acontent corroborates the natural bleaching phenomenon regularly observed in C. crispus populations during summer when N levels are generally low in seawater. These results suggest that C. crispus in the temperate waters of the Bay of Fundy may experience N limitation, but P limitation is unlikely.     

Primary production in papyrus (<Emphasis Type="Italic">Cyperus papyrus</Emphasis> L.) of Rubondo Island,Lake Victoria,Tanzania

Above- and below-ground production and morphological characteristics of papyrus wetlands were measured at monthly intervals from July 2005 to June 2006 at Rubondo Island, Lake Victoria, Tanzania. The average value of live culm biomass (5,789 ± 435 g DW m⁻²) was higher than that of umbel biomass (2,902 ± 327 g DW m⁻²) by 50%. Root to rhizome means biomass value ratio was 1:1.8, rhizome biomass (4,144 ± 452 g DW m⁻²) being higher than roots biomass (2,254 ± 314 g DW m⁻²) by 45%. Direct proportion was observed between shoot density and culm–unit (culms and umbels) biomass. The average value of detritus/litter biomass (1,306 ± 315 g DW m⁻²) was less than total aerial biomass by 86%. The values of biomass are average of 12 sampling months from July 2005 to June 2006.     

Phytoremediation of lead by a wild,non-edible Pb accumulator Coronopus didymus (L.) Brassicaceae

Coronopus didymus was examined in terms of its ability to remediate Pb-contaminated soils. Pot experiments were conducted for 4 and 6 weeks to compare the growth, biomass, photosynthetic efficiency, lead (Pb) uptake, and accumulation by C. didymus plants. The plants grew well having no visible toxic symptoms and 100% survivability, exposed to different Pb-spiked soils 100, 350, 1500, and 2500 mg kg^?1, supplied as lead nitrate. After 4 weeks, root and shoot concentrations reached 1652 and 502 mg Pb kg^?1 DW, while after 6 weeks they increased up to 3091 and 527 mg Pb kg^?1 DW, respectively, at highest Pb concentration. As compared to the 4 week experiments, the plant growth and biomass yield were higher after 6 weeks of Pb exposure. However, the chlorophyll content of leaves decreased but only a slight decline in photosynthetic efficiency was observed on exposure to Pb at both 4 and 6 weeks. The Pb accumulation was higher in roots than in the shoots. The bioconcentration factor of Pb was > 1 in all the plant samples, but the translocation factor was < 1. This suggested C. didymus as a good candidate for phytoremediation of Pb-contaminated soils and can be used for future remediation purposes.     

Structure and properties of agar from two unexploited agarophytes from Venezuela

The red seaweeds Gelidiella acerosa and Gracilaria mammillaris growing along the coast of Venezuela were investigated as potential economic sources of agar. Agar extracted from Gracilaria mammillaris accounted for 27% of the algal dry weight but had quite a poor gelling ability because of the presence of alkali-stable sulphate groups on the D-galactose residue. However, the gel strength of its aqueous solutions was considerably enhanced by the addition of potassium, sodium and calcium ions (up to 1N). On the contrary, the galactan from Gelidiella acerosa (yield of about 20% w/w) exhibited quite good properties. In particular, the gel strength was comparable to that of commercial agaroses. Sulphate esters were not detectable by chemical methods and NMR spectroscopy revealed an agarose backbone with a high degree of methylation on both D and L-galactose residues.     

Extraction of rapamycin (sirolimus) from Streptomyces rapamycinicus using ultrasound

The study was designed to investigate the use of ultrasound-assisted extraction (UAE) of rapamycin (sirolimus) from bacterial strain of Streptomyces rapamycinicus NRRL 5491. To achieve the maximum extraction yield, various parameters were optimized which include S. rapamycinicus (10?g) of biomass in toluene (50?mL), temperature (20°C), acoustic intensity (35.67?W/cm²), and duty cycle (40%) for 4?min extraction time with probe tip length of 0.5?cm dipped into extraction solvent from the surface. The maximum extraction yield 60.15?±?0.01?mg/L was attained under the mentioned optimum parameters. The use of ultrasound for the extraction of rapamycin shows about twofold increase in the yield as compared to the conventional solid–liquid extraction (29.7?±?0.2?mg/L). The study provides the effective UAE technique to produce potential value-added products.     

Kinetics of non-photosynthetic callus production from the brown alga Laminaria setchellii (Laminariales)

White, filamentous, callus-like tissue was produced from the temperate marine brown alga Laminaria setchellii Silva under non-photosynthetic conditions. Explant disks from the medullary core of the stipe section were plated on solid medium (1.5 wt% agar in seawater base, pH 8) at 8 ± 2°C in the dark, and the formation of callus-like tissue was followed as a function of time up to 8 weeks. Although 30% of the total explants plated formed filamentous, callus-like growths, only 3 to 6% of the total explants produced relatively large amounts of filamentous and rounded callus-like cells. The fresh weight yield of this callus-like tissue was 3.74 ± 0.93 mg per 10 mm explant disk (0.053 g callus per g explant). Attempts at establishing a growing, cell suspension of the dispersed callus tissue in PES liquid medium at 24 μmol photon m^?2 s^?1 were not successful.     

Production and properties of agar from the invasive marine alga, Gracilaria vermiculophylla (Gracilariales, Rhodophyta)

The utilization potential, in terms of agar production, of the invasive alga, Gracilaria vermiculophylla, collected at Ria de Aveiro, northwestern Portugal was investigated. The agar yield ranged from 15% to 33%, with pre-extraction treatment with alkali generally increasing the yield. The gel quality (gel strength and apparent Young’s modulus) was best (>600 g cm^?2 and >1,000 kPa, respectively) when alkali treatment with 6% NaOH for 3.5 h was performed. At these pretreatment conditions, the effect of extraction time was also investigated and highest yield and best gel quality were obtained with a 2 h extraction time. By employing these extraction conditions, G. vermiculophylla can be a source of industrial food-grade agar. The structure of agar from G. vermiculophylla was determined through chemical techniques and FTIR and NMR spectrometry. It is mainly composed of alternating 3-linked d-galactose and 4-linked 3,6-anhydro-l-galactose, with methyl substitution occurring at 16–19 mol% of C-6 in 3-linked units and 2–3 mol% of C-2 in 4-linked units. A minor sulfation on C-4 of 3-linked units was also detected; while precursor units (6-sulfated 4-linked galactosyl moieties) were found in the native extract.     

Optimization of the yield and quality of agar from Gracilariopsis lemaneiformis (Gracilariales) from the Gulf of California using an alkaline treatment

The effect of several alkali treatments on the yield, gel strength, rheology, and chemical characteristics (quality) of the agar obtained from Gracilariopsis lemaneiformis from the Gulf of California was analyzed using different alkali concentrations, temperatures and treatment times. In the first stage of the experiment, all treatments lasted 60 min and the NaOH concentrations (2.5, 3.0, 4.0, 5.0, 6.0%) and temperature (80, 90, 100°C) varied. At constant time, temperature played the predominant role, promoting an increase in agar gel strength. Based on the best treatment conditions found (4% and 5% NaOH, and 90°C and 100°C temperature), in the second stage different treatment times (15, 30, 60, 90, 120 min) were used. Since agar yields were not significantly different among temperatures and times, the optimal conditions to obtain best quality agar were those providing the highest gel strength. Treatment time played an important role in increasing gel strength. Maximum gel strength (Nikan, 954 g cm⁻²) was obtained with 5% NaOH at 100°C after 90 min of treatment, though these conditions resulted in an agar yield reduction of 25.5% relative to native agar. This treatment proved to efficiently yield G. lemaneiformis agar that will meet the commercial quality requirements regarding gel strength, 3,6 anhydrogalactose and sulfate content, as well as rheology and hysteresis. Enrique Hernández-Garibay holds a CONACyT scholarship.     

Documentation of the presence of Gmelinoides fasciatus (Stebbing, 1899) and the native benthic fauna in the Volga River at Tver (Tver Region,Russia)

In the Volga Basin, the small Baikalian amphipod Gmelinoides fasciatus was introduced in 1965 into the Gorky reservoir in order to enhance fish production; it appeared in 1986 in the Rybinsk reservoir and we recorded it during monitoring activities in 2006 at Tver. In total, at the monitoring site Tver/Migalovo 69 benthic invertebrate taxa were identified. We compared data from three summer seasons. During summer low flow period Gmelinoides fasciatus did not exceed a share of 12.6% considering individual (ind) densities (mean abundance 165 ± 104 ind m^?2) and 14.2% considering biomass (mean biomass 0.39 ± 0.44 g m^?2). Abundances and biomass of G. fasciatus were shown to be stable over three years and no increase was observed. The monthly dataset (March–November 2008) revealed dynamics in relation to the native benthic communities and it was shown that the maximal densities of Gmelinoides did not exceed 587 ind m^–2. Understanding the effects on benthic communities caused by the invasive amphipod Gmelinoides fasciatus is crucial in order to predict further developments in European inland waters and to establish management strategies.     

Latitudinal variations of the yield and quality of agar from <Emphasis Type="Italic">Gelidium robustum</Emphasis> (Gelidiales,Rhodophyta) from the main commercial harvest beds along the western coast of the Baja California Peninsula,Mexico

The yield and quality of agar from Gelidium robustum from the main commercial harvest beds along the western coast of the Baja California Peninsula (Mexico) were evaluated within a latitudinal range of about 800 km (31°47′N to 27°05′N). Samples from six locations, Bahía Todos Santos, El Rosario, Isla de Cedros, Islas San Benito, Punta Eugenia, and Bahía Asunción, were analyzed. Bryozoan, protein, and agar content in the seaweed were estimated. The agar quality was determined by the content of 3,6-anhydrogalactose, sulfate, gel strength, and gelling and melting temperature. All the values of these variables were correlated and then with the satellite-derived data of the sea surface temperature (SST), net primary production (NPP), and photosynthetic active radiation (PAR) measured at each harvest bed during the summer months (June, July, and August) of 2000. In the northern and central region, the agar yield was 35% to 37% (Bahía Todos Santos, El Rosario, Isla de Cedros, and Islas San Benito), whereas lower yields were obtained from the southern beds (Punta Eugenia and Bahía Asunción). In contrast, the agar quality increased from the northern to the southern beds. A lower gel strength was obtained from Bahía Todos Santos and El Rosario (268 ± 16 and 205 ± 5 gcm⁻²) with a higher gel strength obtained from Isla de Cedros, Islas San Benito, and Bahía Asunción (384 to 444 ± 25 gcm⁻²). Yield was not correlated with the bryozoan content but was inversely correlated with the protein content in the seaweed. The sulfate content in the agar was inversely correlated with the gel strength and with the melting temperature. The 3,6-anhydrogalactose content showed slight variations among harvested beds. Analysis of satellite-derived data showed an equatorward increase of the SST, NPP, and PAR. The agar content correlated inversely with the equatorward increase of the NPP, whereas agar quality, i.e., gel strength, correlated positively with the NPP and PAR. No significant effects were observed on the yield and quality of agar with the latitudinal change of the SST.     

Exploitation and mortality rates of European hake (Merluccius merluccius) in the Aegean Sea (Izmir Bay,Turkey)

Experimental trawl surveys in Izmir Bay (Aegean Sea) were taken seasonally between 2007 and 2009. A total of 1353 specimens were sampled ranging from 5.9 cm (1.4 g) to 44.4 cm (670 g). The main size group of Merluccius merluccius was between 14 and 25 cm total length (TL). In total, the mean catch per unit effort (CPUE) for hake by number and weight was 101.4 ± 18.4 ind h^?1 and 10.7 ± 1.5 kg h^?1, respectively. Highest mean CPUE by number and biomass was determined as 257.1 ± 15.1 ind h^?1 and 15.1 ± 4.9 kg h^?1 in summer. Mortality (M, F, Z) ratios of hake were 0.58 year^?1, 1.66 year^?1 and 2.24 year^?1, respectively. Because of the many smaller specimens caught in this study, this seems to indicate that there may be heavy fishing pressures on the hake population; the high exploitation rate (E = 0.74) appears to confirm this conclusion.     

Studies on Gracilaria changii (Gracilariales,Rhodophyta) from Malaysian mangroves

Gracilaria changii, recorded from Malaysia and Thailand, is one of the more abundant agarophytic seaweeds found in Malaysia. A wild population of Gracilaria changii growing in mangroves was monitored for seasonal variation in agar content and gel strength as well as spore production. Agar yield and gel strength ranged from 12 to 25% dry weight and 294 to 563 g cm^–2, respectively, over a 15-month period. Gel strength but not yield was positively correlated with amount of rainfall. Cystocarps were observed throughout the study, but use of sporetraps showed that spore release peaked around July–August and January–February after the two monsoon periods.Mariculture of Gracilaria changii in shallow ponds in the mangroves, in an irrrigation canal and in a shrimp farm pond was conducted. Average growth rate of cuttings tied to monofilament lines was 3.3 ± 1.7% d^–1, 8.4 ± 1.8% d^–1 and 3.6 ± 1.6% d^–1 respectively. Cuttings were lost to siltation, wave action, predation and heavy epiphytisation.These studies show that Gracilaria changii has potential commercial application in the agar industry.