Summary of Biology doctoral thesis: Studies on biodiversity and economic potential of seaweeds in Phu Yen province

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Immediate objective: Identification of the seaweed species composition and its distribution characteristics; evaluation of economic potential seaweed species to establish and manage its exploitation and conservation areas in Phu Yen province.

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Nội dung Text: Summary of Biology doctoral thesis: Studies on biodiversity and economic potential of seaweeds in Phu Yen province

MINISTRY OF EDUCATION VIETNAM ACADEMY OF AND TRAINING SCIENCE AND TECHNOLOGY GRADUATE UNIVERSITY OF SCIENCE AND TECHNOLOGY ……..….***………… NGUYEN THI THU HANG STUDIES ON BIODIVERSITY AND ECONOMIC POTENTIAL OF SEAWEEDS IN PHU YEN PROVINCE Specialty: Ecology Code: 9 42 01 20 SUMMARY OF BIOLOGY DOCTORAL THESIS Ha Noi – 2021
This thesis is completed at: Graduate University of Science and Technology - Vietnam Academy of Science and Technology Supervisors: 1. Nguyen Ngoc Lam, Prof., Ph.D. 2. Nguyen Van Tu, Ph.D Referee 1: …………………………………… Referee 2: …………………………………… Referee 3: …………………………………… This Dissertation will be defended in front of the Dotoral Examination Board of Graduate University of Science and Technology, Vietnam Academy of Science and Technology at …..:…. H, Date ....../....../2021. The dissertation can be accessed from: - The library of Graduate University of Science and Technology - The National Library of Viet Nam
1 INTRODUCTION 1. The necessity of the thesis project Seaweed is a marine resource with very high direct and indirect use values. So most of the countries with the sea are very interested in this resource. In Viet Nam, seaweed farming is one of a new industry (replacing traditional shrimp farming which is in crisis in profit value and pond pollution). Seaweed is a potential object in the construction and socio-economic development, contributing to hunger eradication and poverty reduction for many coastal farming households. In coastal areas and islands of our country, about 800 species of seaweed have been discovered at present. In the coastal areas and islands of our country, about 800 species of seaweed have been discovered, in Phu Yen, there have been some studies on seaweed, in studies officially published for Phu province. Yen has 34 species including 6 species of cyanobacteria (Cyanophytes), 8 species of Chlorophytes, 9 species Phaeophytes and 11 species of Rhodophytes. While neighboring provinces in the Central and South Central regions show, seaweed species diversity is quite high such as Quang Ngai with 190 species, Binh Dinh 78 species, Khanh Hoa 516 species, Ninh Thuan 121 species, Binh Thuan 210. species. Therefore, the question raised in this thesis is how many species of seaweed, distribution characteristics of the species, and reserves of some species of seaweed that are valuable for food, medicine, ... will it be recorded in coastal waters of Phu Yen province? To be able to answer the above question, the thesis topic: "Studies on biodiversity and economic potential of seaweeds in Phu Yen province" is addressed with the following objectives and contents: 2. Objectives of dissertation Long-term objective: - Contribute to the study of the seaweed identification in Viet Nam Immediate objective - Identification of the seaweed species composition and its distribution characteristics - Evaluation of economic potential seaweed species to establish and manage its exploitation and conservation areas in Phu Yen province. 3. The main contents of dissertation To achieve the above objectives, the research contents have been carried out including:  Research on species composition and distribution characteristics of seaweeds.  Identify seaweed species with economic potential and analyze chemical composition of some economic seaweed species.  Mapping of spatial distribution and estimating biomass of some economic seaweed species in Phu Yen province.
2 Chapter 1. AN OVERVIEW 1.1. Studies on biodiversity and economic potential of seaweed in the world Studying the biodiversity of seaweeds as well as other marine plants had been promoted since the systematics of kingdoms was proposed by Carl Linnaeus. Seaweed taxonomy and its classification were complemented and contributed by many scientists during the 17th to 19th centuries. 1.1.1. Systematics Up to now, the world had discovered about 12,000 seaweed species arranged in 4 sections: > 7,000 species for Rhodophytes; > 2,000 species for Ochrophytes; about 1,500 species for Chlorophytes, and about 1,500 species for Cyanophytes (Cyanobacteriophytes). 1.1.2. Seaweed cultivation The main cultured seaweed species belong to about 30 genera Agardhiella, Eucheuma, Gelidium, Gigartina, Gracilaria, Hydropuntia, Hypnea, Kappaphycus, Merwastotheca, Porphyra (red algae - rhodophytes); Saccharina, Laminaria, Undaria, Cladosiphon (brown algae - ochrophytes) and Monostroma, Ulva, Caulerpa (green algae - chlorophyyes). Species of the genera Agardhiella, Gelidium, Gigartina, Porphyra, Saccharina, Laminaria, Undaria, Monostroma, and Ulva were commonly cultivated in temperate waters, while species belonging to the genera Eucheuma, Gracilaria, Hydropuntia, Hypnea, Kappaphycus, Cladosiphon, Caulerpa cultivated in tropical and subtropical regions. 1.1.3. Seaweed uses Seaweed has long been used in many fields: as raw materials for medicine production, extraction of some types of glue (agar, alginate, carrageenan), gas production, fertilizer, environment treatment, make food as a form of green food for people, and used as medicine. 1.2. Biodiversity and economic potential seaweeds in Viet Nam. 1.2.1. Biodiversity of seaweeds In Viet Nam, the studies on seaweeds period before 1954 has completely done by foreigners. After 1954, the studies have been started by Vietnamese scienttists. Some research publications have been published such as Marine Algae from Southern part, Marine Algae from Northernpart, Monographs of Sargassum, Gracilaria on aspect of taxonomy, resources and uses. Presently, 800 species of seaweeds have been registerred from Vietnasmese waters. 1.2.2. Seaweed resources . In the South, before 1975, there was only one project that mentioned seaweed resources, that was the work of Luong Cong Kinh from the Institute of Oceanography. In the North, there were few studies on seaweeds concentrated in culture of Gracilaria in Quang Ninh, Hai Phong waters .
3 1.2.3. Biological active ingredient and chemical composition of seaweeds In seaweed, there were many different bioactive compounds, those were mainly colloids such as agar, carrageenan, alginate, pigments, steroids, proteins, enzymes, lectins, vitamins, growth stimulants and chemical elements. 1.2.4. Using seaweeds Using seaweeds to treat seawater environmental pollution, to absorb excess CO2 contributes to minimize effects of greenhouse and climate change, to produce biofuel, to make food, to use seaweeds as animal feed and fertilizer, medicine, extracting some substances (arachidonic acid, phenolic) used as functional foods. 1.2.5. Cultivation of seaweeds Local people from coastal provinces of central Viet Nam was cultivating some seaweed species such as Kappaphycus alvwerezii; Gracilaria bailiniae and Caulerpa lentillifera. Most of agarophytes in Vietnam were used as green vegetable or extracted agar-agar. Currently, the area of agarophyte farming was about 9,830 ha, accounting for about 50% of the aerea capable of cultivating (18,050 ha). Seaweed ponds in the central provinces was usually 1-2 ha in area, while in the northern and southern provinces were about from 5-25 ha, with a production of 47,700 tons of fresh (appr. 7,000 tons dry), the average yield was about 5 tons of fresh /ha /year. Carageenophytes (Kappaphycus alvwerezii) were originated /imported from the Philippines and were commonly cultured in Viet Nam by the ways: 1) on floating rafts in open sea along the central coast; 2) grown in a shallow lagoon and semi-open bays with sand and mud bottoms; and 3) culture in ponds. Sea Grapes, Caulerpa lentilifera (edible Caulerpa) had been developing in South Central provinces such Khanh Hoa, Ninh Thuan, and Binh Thuan. Sea grapes were well cultured in abandoned ponds of shrimp farms, it can be harvested after 15-20 days. 1.3. Natural conditions in the studied waters 1.3.1. Geographical location Phu Yen province was a coastal province in the South Central Coast, with coordinates from 13⁰34’35 ”to 12⁰49’39” North Latitude and from 109º17’40 ”to 109o23’27” East Longitude. Phu Yen province had a coastline of about 189 km, meandering, with many mountain ranges running close to the sea, forming bays and lagoons. Along the coast, there were estuaries and creeks such as Tan Quy (O Loan lagoon), Da Dien (Da Rang estuary), Da Nong (Ban Thach estuary) and Vung Ro Bay that had advantages in tourism development, water transport, fishing, and aquaculture. Vung Ro and Xuan Dai Bays were wide, deep sheltered waters that prefer for fishery development and aquaculture. 1.3.2. Hydrological conditions Phu Yen was located in a typical monsoon tropical climate. Water temperature tends to change slowly comparing to air temperature. The highest temperature was falling in June (the dry season) and the lowest temperature in December (the rainy season). Water temperature in the rainy season ranges from 23-27.6ºC,
4 average of 25.2ºC and in the dry season ranges from 23.8-31.5ºC, average of 27.8 ºC. Thus, the average temperature difference between the two seasons was about 2.5ºC. Offshore salinity was above 33.6 - 34. In coastal wereas, the salinity ranges from 31 to 32. In the lagoons, although the salinity decreases, it was still quite high, reaching about 20-30. 1.3.3. Driving force Phu Yen was located in the South Central Coast, so the seasonal variations in both wind speed and direction were clearly shown. The existence time of the Northeast monsoon is from October to April of the following year, of which, strong wind is November and December. The prevailing Southwest monsoon is from May to September and the strongest wind period is July and August. The Northeast monsoon period is longer than that of Southwest monsoon. The Northeast monsoon speed is also stable and greater than that of the Southwest monsoon. 1.3.4. Current status of water quality in coastal waters of Phu Yen province The monitoring for water quality was carried out by the Environmental Monitoring Center. There were some parameters exceeding the permwassible limit such as content of TSS, COD, NH+4, Mn. Chapter 2. OBJECTS, MATERALS AND METHODS 2.1. Obsjects, locations and duration of studies Seaweed species in the coastal waters of Phu Yen province were collected according to the Temporary Code of Marine Investigation esteblished by the National Science and Technology Committee (1981), from June 2017 to May 2019 at 19 survey localties in 9 areas in the coastal zone of Phu Yen province are shown in Table 2.1. Table 2.1. Position of survey localities in the coastal waterts of Phu Yen Province. Latitude, Longitude, Code Area Locality N E V1 Cu Mong Laggon Nom Beach 13°56'86.10" 109°29'32.52" Tram Beach 13°55'09.68" 109°27'97.24" Hoa Loi 13°52'57.23" 109°28'27.62" Nan Islet 13°52'20.19" 109°27'21.77" Vinh Hoa 13°52'65.47" 109°29'09.14" V2 O Loan Lagoon O Loan Lagoon 13°16'53.98" 109°17'8.18" V3 Da Dien Estuary Da Dien Estuary 13° 4'57.73" 109°19'59.75" V4 Da Nong Estuary Da Nong Estuary 12°56'52.21" 109°25'37.03" V5 Rang Beach Rang Beach 13°65'32.26" 109°23'12.57" V6 Tu Nham Beach Tu Nham Beach 13°50'68.91" 109°30'01.77" V7 Coast from An North My Quang 13°18'60.70" 109.30'40.16" Ninh Dong to Chua Islet 13°17'37.51" 109°31'03.69" Đà Dien Estuary Dua Islet 13°16'66.14" 109°32'14.34" Yen Islet 13°22'59.42" 109°30'24.42"
5 Latitude, Longitude, Code Area Locality N E Mai Nha Islet 13°28'41.67" 109°32'90.91" V8 Coast od Dong Hoa Nua Islet 12°82'69.51" 109°39'16.88" Commune Dian Cape 12°89'73.99" 109°45'43.20" V9 Xuan Dai Bay Ong Xa Islet, 13°39'50.67" 109°24'15.14" Xuan Phuong 13°44'40.70" 109°28'23.17" Ward In which, the localities of V1, V2, and V9 represent the lagoon ecosystem; the areas V3 and V4 represent estuarine ecosystems; the remaining V5-V8 areas represent the reef ecosystem. Figure 2.1. Map of survey location (O) seaweed in the coastal area of Phu Yen province
6 During the survey in May 2019, biomass of 6 seaweed species were collected, among them, 5 species such as Chaetomorpha aerea, Caulerpa racemosa, Turbinaria ornata, Sargassum mcclurei, Gracilaria salicornia from My Quang area and one species Gracilaria tenuistipitata from O Loan lagoon area were analyzed for its protein, lipid, ash, and amino acid contents. 2.2. Data of remote sensing The interpretation of distribution of seaweed bed in the coastal waters of Phu Yen province, mainly concentrated in the species of Sargassum. Ecologically, Sargassum in Phu Yen well grown in May - June every year, then fades in low water temperature of rainy season, NE monsoon. The selection of the image scenes taken in the middle of June 2018 is sufficiently to represent the distribution of Sargassum in Phu Yen. Application of remote sensing techniques combined with GIS technology in order to evaluate the distribution and biomass of Sagassum in coastal waters of Phu Yen province. To do this, remote sensing images with high resolution, good radiation resolution (such as Sentinel 2 image (10m; 12 bit), PLanetScope (3.5 m; 12 bit) were selected for distributing and estimating biomass and reserves. Spectral bands of MSI - Sentinel-2 images such as B2, B3, B4 and B8 have a resolution of 10m, are the main documents used to interpret coastal habitats. Two scenes of MSI - Sentinel-2 taken on June 2018 are mainly used in interpreting coastal habitats (coral reefs, seagrass and seaweed bed) in the coastal areas of Phu Yen province, specifically: Landscape First image, image MSI - Sentinel-2B bearing number: L1C_T49PCR_A010511_20170627T031358, taken on June 27, 2018, covering the coastal line from Hoai Huong commune, Hoai Nhon district, Binh Dinh province to Xuan Phuong commune, Xuan Dai bay and the second photo, photo MSI - Sentinel-2B bearing number L1C_T49PCQ_A010511_20170627T031358, taken on 27th June 2018 covering the coastal line from Xuan Canh commune (Xuan Dai bay) to Van Khanh commune, Van Ninh district, Khanh Hoa province. PlanetScope image with code 20180628_024114_1004_1B_AnalyticMS was used for this study. This remote sensing image was taken on the same day of seaweed sampling, on the same day with the lowest tide level in the month (June 15, 2018 lunar calendar). 2.3. Study methods of seaweeds 2.3.1. Identifying species composition The survey of the tidal zone is based on the Temporary Integrated Marine Investigation Code (part of seaweed) issued by the State Committee of Science and Technology in 1981 and the "Code of Investigation of Marine Resources and Environment. Surveying the sub-tidal zone with SCUBA diving equipment, the Olympus TG 5 digital underwater camera (Viet Nam). Specimens were analyzed for species composition in the Dept. of Marine Plants, Institute of Oceanography (Vietnam Academy of Science and Technology). The identification is based on the criteria of the thallus morphology and the internal structure under Motic A300 microscope at different objectives (4X, 10X, 40X and 100X).
7 The taxomnomic litteratures such as Pham Hoang Ho (1969), Nguyen Huu Dinh et al, (1993), Taylor (1960), Cribb (1983), Tseng (1983), Yoshida 1998[, Tsutsui et al. 2005, Titlyanov and Titlyanova, 2012, are used for identifying species. Taxonomic information is updated by http://www.algaebase.org. 2.3.2. Dominant species The dominant species and species groups are assessed based on the frequency of occurrence (f) of the species, the dominant, common, rare, and rare seaweed species 2.3.3. Seaweed flora Character of seaweed flora was calculated by Cheney Index,: C= (Species number of red algae + Species number of green algae) /Species number of brown alge. 2.3.4. Distribution of seaweeds The Sorensen Similarity index (S), S = 2C / (A + B) was used to compare the seaweed communities in survey areas. In which, A and B are the number of species at locality A, B respoectively and C is the sharing number of species of A and B localities. Distribution by tidal zone: The study of vertical distribution of seaweed is based on the principle of dividing into the tidal zone in the coastal part including different areas based on tidal level, including high tide, mid tide and low tide. Tidal levels are based on tides at Nha Trang station in June, November 2017, and April June 2018. 2.3.5. Analyzing the nutrient concentration of seaweeds About 2 kg of fresh seaweed are collected and washed with marine water and then with fresh water to remove the salt out. Seaweeds are stored immediatelyin the field at temperature ≤ 4ºC by cold box with dry ice. In the lab, seaweeds were frozen in deep freezer at -20ºC and -47ºC. The specimen was sent to Case - Center for Experimental Analysis Services for analyzing lipid, protein, ash, amino acid content analysis. 2.3.6. Analysis of PCA PCA analysis technique is processed by the tool "PCA add-in" running on Excel software. In this study, PCA analysis indicated that the first two main components (PCA1 and PCA2) will explain the information about concentration variation in amino acid components in seaweed samples. PCA analysis allows grouping of algae samples according to amino acid composition . 2.3.7. Estimating the yield /reserves of seaweeds In the coastal tidal zone, the transect was vertically placed from the high tide to the sub-tidal zone to the still distributed seaweed. The transects are placed parallel to each other, the distance between them depends on the length of the investigation site, the distribution of the algae and the random sites. It was noted that the distance between two sites is not more than 100m.
8 Sampling on vertical transect using a biomass 0.25 m2 quadrat. After sampling, the seaweeds were drained and weighed fresh in the field before bringing them to the laboratory. In the laboratory, samples are washed with fresh water before drying in the oven for 24 hours at the temperature of 60ºC, let cool in a desiccator and weighed. Estimate biomass: use the formula B = (b1 + b2 +… bn) / n; b1, b2, ... bn is the biomass at the first, second,… n. Estimated seaweed reserves are calculated by the formula: W = B x S; in which: B: average biomass, S is the area of distribution of seaweeds. However, because seaweeds in the study area is distributed according to the leopard type, we need to calculate the coverage of seaweed to calculate the reserves more accurately. At that time: Seaweed reserves = quantity x coverage x area of distribution. Coverage calculation: applied coverage method of Saito and Atobe (1970). Use a square quadrat with an area of 0.25 m2. This quadrat is divided into 25 squares of equal areas. Quadrat was placed along the cross-section perpendicular to the shoreline with the starting point of the inner belt of the seaweed carpet and the ending point being the outer belt of the seaweed mat. Score a score in each sub-plot from 1 to 5. (Table 2.4). Coverage is calculated by the following formula: C (%) = ( Qn5 X C5) + ( Qn4 X C4) +( Qn3 X C3) +( Qn2 X C2)+ ( Qn1 X C1), trong đó: - Qnn is the total of number of countable squares in the quadrat, - Cn is coefficients from table 2.4 Bảng 2.4. Categories of percent cover and its coefficient. Categ Coverage / quadrat Coefficient (Cn) ories 5 >1/2 3.0 4 1/4 - 1/2 1.5 3 1/8 - 1/4 0.75 2 1/16 - 1/8 0.375 1
9 applied, using the formula for calculating the reliability of Spearman - Brown: rSB = 2 * rhh / 1 + hh, where: rSB: confidence trusted Spearman- Brown; rhh: parity correlation coefficient; If rSB ≥0.7 is reliable data; If rSB
10 169 seaweed species had been identified belonging to 24 orders, of which the Ceramiales order had the highest number of species with 27 species, accounting for 15.98% of the total species, followed by the Bryopsidales order and the Cladophorales with 22 species, accounting for 13.02%, order Gigartinales (13 species - 7.69%), order Fucales and Nemaliales order (12 species - 7.10%), order Ulvales (10 species - 5.92%), order Dictyotales (9 species -5.33%) the remaining orders had from 1 to 6 species and an average of 2.63 species / set, accounting for 24.85% of the total species. 49 seaweed families had been identified: Rhodomelaceae family had the largest number of species with 13 species, followed by Sargassaceae with 12 species, Ulvaceae with 10 species, Dictyotaceae, Cladophoraceae and Galaxauraceae all had 9 species. The rest had from 1 to 8 species. 3.2.2. Diversity of classification levels The number of seaweed species identified in this study was not high, but they were relatively rich in diversity of classification. Details of the diversity of seaweed classification levels in the coastal waters of Phu Yen province were shown in Table 3.1. - Level of phylum: There was one class only in each phylum - Level of class and family: Rhodophytes with 13 orders (54.17%) and 27 families (55.10%); Chlorophytes with 5 orders (20.83%) and 15 families (30,61%); and Cyanobacteriophytes, and Ocrhophytes with 3 orders for each (12.5%) and 4 families (8.16%) and 3 familes ( 6.12%), repectively. Table 3. 1. Diversity of classification levels. N = Number of taxa. Class Order Family Genus Species Phylum N % N % N % N % N % Cyanobacteri- 1 25 3 12.5 4 8.2 2.4 ophytes 4 4.8 4 Rhodophytes 1 25 13 54.2 27 55.1 48 57.8 83 49.1 Chlorophytes 1 25 5 20.8 15 30.6 23 27.7 59 34.9 Ochrophytes 1 25 3 12.5 3 6.1 8 9.6 23 13.6 Total 4 100 24 100 49 100 83 100 169 100 - Level of species: Rhodophytes with 48 genera and 83 species (49.11% of species total), Chlorophytes with 23 genera and 59 species (34.91 % of species total), Ochrophytes with 8 genera and 23 species ( 13.61 % of species total), and Cyanobacteriophytes with 4 genera and 4 species (2.37 % of species total). 3.2.3. Characteristic of species composition Seaweed species composition was divided into basic groups based on the frequency of their occurrence in the survey area. 20 dominant species, 60 common species and 85 less common species had been identified. Dominant species/species groups The study results showed that dominant species and groups of species were mainly in the genus Sargassum, Turbinaria, Padina, Ulva, Caulerpa, Hypnea pannosa in Hon Nua, Mui Dien, My Quang, Hon Chua, Hon Dua, Hon Yen, Cu Lao Ro Nha, Cu Lao Ong Xa, Tu Nham, Bai Nom, Bai Tram, Hoa Loi, Hon
11 Nam, Bai Chaetomorpha aerea is the dominant species in the area of My Quang, Hon Yen (or Mui Yen - Tuy An district) while Gracilaria tenuistipitata is the dominant species in O Loan lagoon, Cu Mong lagoon. . Applying Cheney ratio ratio between total species of red seaweeds and green seaweeds divided by the number of species of brown seaweed is (83 + 59) / 23 = 6.17. Thus, the algal flora of Phu Yen is tropical. 3.3. Distribution characteristics of seaweed 3.3.1. Distribution of seaweed among study area The distribution and number of seaweed species among the study areas were not uniform (Figure 3.3). The similarity coefficients of species in the survey areas were about 0.04 (between V3 and V4 and V6) to 0.82 (between the V3 region and V4) and the average was 0.25. The similarity coefficient between the region V3 and V4 vs. V6 reaches the smallest value (0.04). The average value of the similarity coefficient of seaweed in the whole Phu Yen province was not large (0.25) due to the inconsistent sea floor of 3 ecological types including estuaries, lagoons and coral reefs. Species number 140 130 120 100 80 56 60 47 43 38 37 40 15 10 12 20 0 V1 V2 V3 V4 V5 V6 V7 V8 V9 Study area Hình 3.3. Distribution of species number among study areas. 3.3.2. Vertical distribution of seaweeds 80 species were distributed in the tidal zone, 130 species were distributed in the sub-tidal zone and 40 species were found in both tidal and subtidal areas. Table 3.3. Vertical distribution of seaweeds in tidal zone Seaweed distribution Supralittoral From very few (Pyropia spp.) to no seaweeds (Supratidal zone) Mean spring tidal level up to 3.3 m Littoral High tidal Ulva spp., Gelidiella acerosa, Symploca hynoides (Intertidal zone) zone Mean spring tidal level at the equator 1.6 m.
12 Ulva spp., Gelidiella acerosa, Boodlea coacta, B. Middle tidal composita and many species zone Mean neap tidal level at the equator 0.6 m. Caulerpa spp., Halimeda spp., Sargassum spp., Low tidal Padina spp., and many species zone Mean neap tidal level at the 0 m chart. Subtidal zone Halimeda spp., Sargassum spp., Padina spp, Amphiroa (Sublittoral) From 0 to -10 m The majority of seaweed species here were mainly distributed from mid tidal zone to a depth of 4 m compared with 0 m of the chart, often flooded, protected by waves outside by the coral belt. On each layer of depth, there were a number of specific genera and species at each tidal zone (Table 3.3). 3.3.3. Seaweed distribution in different substratum In the Phu Yen coastal water, there are two substrate types related to seaweed distribution . They are hard bottoms (corals, rocks, gravels) and soft bottomsd (sandy mud, fine sand mixed with fragments of mollusks and small gravels). 3.4. Resources 3.4.1. The economic species /species groups of sdeaweeds 64 species of economic seaweed are recordfed, they are 19 Rhodophyte, 22 Ochrophytes, and 23 chlorophytes. Among them, genera such as Sargassum, Gracilaria, Porphyra have large yield and high value for local economic development. 3.4.2. N utrient composition of some economic potential seaweeds in Phu Yen Protein content: In the 6 species studied, the protein content of seaweed varied between phyla and species (Table 3.4). Gracilaria tenuistipitata has the highest protein content (17.2% Dry Weight (DW)), followed by 2 species of Brown seaweed Sargassum mcclurei (6.8% DW), Turbinaria ornata (4.23% DW). The protein content was low in three species of Caulerpa racemosa (2.5% DW Gracilaria salicornia (1.07% TLK), and the lowest was Chaetomorpha aerea (0.84% DW). The protein content has a large variation in the Red seaweed industry (1.07 - 17.2%). Lipid content: Lipid content assessment showed that there were differences between species (table 3.4). The highest lipid content belonged to Turbinaria ornata (0.666% DW), followed by Chaetomorpha aerea (0.244% DW), Caulerpa racemosa (0.178% DW), Gracilaria salicornia (0.135% DW), Sargassum mcclurei (0.13% DW). and finally, Gracilaria tenuistipitata (0.12% of total yield). Ash content: The ash content in the seaweed analyzed was highest in the brown seaweeds, in the red seaweeds and the lowest in the green seaweeds (table 3.4). The highest ash content was from Sargassum mcclurei (33.2% DW), to Gracilaria tenuistipitata (17.4% DW), Turbinaria ornata (16.7% DW), Caulerpa racemosa (4.1% DW), Gracilaria salicornia (4% DW) and lowest is Chaetomorpha aerea (3.22% DW). Amino acid content: 16 types of amino acids are found in the 6 above seaweed species.
13 Table 3.4. Concentrations of lipid, protid, and ash of 6 species of seaweeds from Phu Yen, May 2019 Ca =Chaetomorpha aerea, Cr =Caulerpa racemosa, To = Turbinaria ornata, Sm = Sargassum mcclurei, Gt = Gracilaria tenuistipitata,Gs = Gracilaria salicornia) Green algae Brown algae Red algae Chỉ tiêu Unit Ca Cr To Sm Gt Gs Lipid % 0.24 0.18 0.67 0.10 0.10 0.14 Protein % 0.84 2.50 4.23 6.80 17.20 1.10 Ash % 3.22 4.10 16.70 33.20 17.40 4.00 PCA analysis (Figure 3.4) from 6 seaweed samples collected in Phu Yen can be divided 3 groups: Group 1 includes MK1, MK2 and MK3, group 2 contains MK4 and MK6, and group 3 contains MK5. ((MK1 = Chaetomorpha aerea, MK2 = Caulerpa racemosa, MK3 = Turbinaria ornata, MK4 = Sargassum mcclurei, MK5 = Gracilaria tenuistipitata, MK6 = Gracilaria). Figure 3.4 shows the content of arginine, aspatic acid and glutamic acid representing the differences between groups of seaweeds. The average content of arginine in seaweed of groups 1, 2, 3 are 0.127 g, 0.255 g and 1.23 g, respectively. The average content of glutamic acid in seaweed of groups 1, 2, 3 are 0.97 g, 0.543 ga and 1.35 g, respectively. The average content of aspatic acid in seaweed of groups 1, 2, 3 are 0.44 g, 0.62 g and 1.17 g, respectively (Figure 3.5) Figure 3.4. Principal Component Analysis of Figure 3.5. Concentration of glutamic acid, 6 species of seaweeds from Phu Yen. arginine, and aspartic of 6 species of seaweed from Phu Yen, 05/2019.
14 3.4.3. Estimating the biomass of economic seaweed groups The highest yield belongs to Sargassum spp. (934 ± 227 g /m2), following Turbinaria (158 ± 93 grams /m2) and there was a huge difference with red algae as well as green algae, especially the lowest was Halymenia dilatata. (5 ± 2 g / m2) and the genus Codium (7 ± 3 g / m2). 3.4.4. Estimating the production and economic algal group Estimate the production of brown algae Brown seaweeds with the largest natural production of of all seaweed phylum, in which the Sargassum has the highest yield with 1380.22 tons /year), Turbinaria with 12.6 tons /year, and Chnoospora implexa with 3.3 tons / year, while other groups of seaweed have negligible natural reserves. Resuls of GIS, remote sensing and field surveying methods for seaweed mapping and biomass estimating of Sargassum meadows in Phu Yen coastal waters are introduced in figures 3.6 a -3.6i and figures (3.7a - 3.7i). Classification results of Sargassum canopies and other substrates from satellite image base on enhanced BRI techniques, using GIS to estimate the size of the distribution areas in the coastal waters of Phu Yen were reported (Table 3.6). Table 3.6. Total production (tons), covered area (hectares ), average biomass (g /m2) of Sargassum in coastal waters of Phu Yen province, Vietnam from PS images, Sentinel images and field surveys. Total Area Average Biomass Order Areas Length (Meters) Production (Hectares) (Gram / m3) (Tons) 1 Rang Beach 5.96 17,660 654±202 (n=15) 31.18 2 Nom Beach to Tram Beach 13.52 43,200 957±60 (n=15) 103.47 3 Vinh Hoa, Nan Islet, Hoa 23.98 60,160 1,078±122 (n=15) 181.02 Loi, Tu Nham 4 Xuan Dai Bay 40.30 100,700 567±51 (n=15) 205.56 5 Mai Nha Islet 42.64 55,460 1,042±104 (n=15) 355.39 6 Yen Islet 1.39 4,560 748±108 (n=15) 5.20 7 An Chan 50.32 993±196 (n=15) 449.5 8 Dien Cape 3.36 11,700 1,130±160 (n=15) 34.17 9 Nua Islet 1.49 4,760 1,236±121 (n=15) 14.73 Total amount 182.96 1380.22 Sargassum resources is widely scattered distributed on rocks or dead corals in almost of the study localities with the area up to 182.96 hectares. Sarrgassum is strongest development in Chua Islet (An Chan), Mai Nha Islet, Rang Beach.
15 Figure 3.6a-e. Sargassum distribution maps in the areas: - a. An Chan commune, - b. Yen Islet, - c. Mai Nha Islet, - d. from Nom Beach to Tram Beach , - e. Hoa Loi, Nan Islet, Vinh Hoa (Cu Mong lagoon). In the An Chan, this resource is found with area about 50.32 hectares (Figure 3.6a), 1.39 hectares in Yen Islet (Figure 3.6b), 42.64 hectares in Mai Nha Islet (Figure 3.6c), 13.52 hectares in Nom Beachto Tram Beach (Figure 3.6d), 23.98 hectares in Hoa Loi, Nam Islet, Bay Hoa, Tu Nham (Figure 3.6e), 5.96 hectares in Bai Rang (Figure 3.6f), 40.3 hectares in Ong Xa Islet, communes Xuan Phuong, Hon Yen, Bai Om, Vung Quan, Da Dia Reef (Figure 3.6g), 3.36 hectares in Dien Cape (Figure 3.6h), 1.49 hectares in Nua Islet (Figure 3.6i). Estimating predictive biomass using the multivariate linear regression function and to increase the accuracy of the predictive function, we compute more multivariate regression by quadratic polynomial. Performance of each regression model (regression Univariate linearity, multivariate linear regression and quadratic polynomial regression are presented in (Appendix 3) Sargassum biomass map results are generated
16 from biomass prediction models using regression algorithms regression of quadratic polynomial (Figure 3.7a - 3.7i). Figure 3.6f-i. Sargassum distribution maps in the areas (cont.):- f. Rang Beach, - g. Xuan Dai Bay, - h. Dien Cap, - i. Nua Islet.
17 Figure 3.7a-e. Sargassum biomass maps in the areas: - a. An Chan commune, - b. Yen Islet, - c. Mai Nha Islet, - d. from Nom Beach to Tram Beach , - e. Hoa Loi, Nan Islet, Vinh Hoa (Cu Mong lagoon). The Sargassum yield obtained from the biomass map is estimated by using the GIS tool is shown in (table 3.6) with a total yield of 1,380.22 tons in 182.96 ha cover area so the Sargassum biomass is average. of the whole province is 934 ± 227 (gram /m2).
18 Figure 3.7a-e. Sargassum biomass maps in the areas: (cont.):- f. Rang Beach, - g. Xuân Đài Bay, - h. Dien Cape, - i. Nua Islet. Estimate the production of green algae The reserve of green seaweed resources is about 172.02 tons /year, of which, Ulva genus has the highest resource reserve of 110.27 tons /year), especially Ulva lactuca is present in most study areas in the coastal waters of Phu Yen province, but mostly in My Quang, Tu Nham with reserves of natural resources about 110.27 tons /year. Estimate the production of red algae The highest source of Gracilaria 407,932 tons /year following Hypnea genus with 20.5 tons /year and Ceratodictyon spongiosum with 20.2 tons /year. Porphyra vietnamensis with 10.5 tons /year, and calcified algae - Amphiroa fragilissima with 8.3 tons /year. Natural reserves of other seawees are negligible. Comparing with the economic seaweed resources of Ly Son archipelago, as shown in Figure 3.8, the reserves of Hypnea, Gracilaria (excluding Gracilaria tenuistipitata), Sargassum, Chnoospora, Ulva have lower reserves than Ly Son archipelago.