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A survey on the status of seagrass resources was Conducted by inspecting the point where there is a seagrass line to see the area boundaries of each seagrass source type of seagrass and estimate the percentage of area coverage. The operation is divided into two parts:

(1) Survey during low tide record the coordinates along the edge of the area where seagrass cover is set the survey line perpendicular to the coast to the end of at least 3 seagrass lines, place 4 sampling frames (Quadrat) size 50x50 cm, every equal distance, at least 30 survey points along the survey line according to the Line Transect method of UNEP (2004) to record survey point coordinates with the Global Positioning System (GPS) tool and note the variables such as percentage of seagrass cover and open parts or cover of algae the ground looks like sand, gravel, or a type of seagrass that can be seen with the naked eye. Take note of the seagrass species. Collected specimens of unidentified seagrass with the naked eye to classify species in the laboratory record data on sea water quality and other environmental data.

(2) Survey during high tide use the scuba diving method to explore. By specifying survey lines perpendicular to the shoreline to the end of the seagrass line at least 3 lines and place four sampling frames (Quadrat) size 50x50 cm, every equidistant, at least 30 survey points along the survey line. If the survey line cannot be determined Use a spot check dive to cover the entire seagrass area. Record the coordinates of the survey point, and surveyors will take note of the variables, including the percentage of seagrass covered and open parts or cover of algae The ground looks like sand, gravel or a type of seagrass that can be seen with the naked eye. Take note of the seagrass species. Collected specimens of unidentified seagrass with the naked eye to classify species in the laboratory recorded data on seawater quality and other environmental data.

Surveys and monitoring of seagrass status in Thailand by the Department of Marine and Coastal Resources since 2004 to the present found that each year the survey distribution area of each seagrass source moved back and forth as appropriate for the environment of the area at that time, such as the intensity of wind waves seafloor, characteristics, desiccation and seasons, etc. Therefore, the area has been reported to find seagrass. Therefore, it is considered a potential area for seagrass to grow. When the environment is suitable including adding new seagrass areas that have not reported before because seagrass is a flowering plant, it can reproduce sexually this makes it possible to find seagrass growing in areas far from the original seagrass sources, such as Koh Chang, Ranong Province, Ao Kan Kradai, Prachuap Khiri Khan Province, Koh Nu, Songkhla Province.

In addition, the Department of Marine and Coastal Resources Seagrass planting has been carried out to restore seagrass resources according to the Integrated Seagrass Restoration Project from 2018 to 2020, increasing the seagrass area to a total area of 123 rai. some seagrass has permanently lost space from the natural environment has changed. Until it is not suitable for the growth of seagrass, such as sea grass resources in Phetchaburi province and Phatthalung province and from the impact of human activities, The conditions of the area are not suitable for the growth of seagrass, such as the seagrass resources at Sai Kaew Beach, Songkhla province, etc.

These seagrass resource areas were surveyed for their health status, with repeat surveys in the same rotation area over four years (the last survey was in 2018 - 2021) or more frequent in some vulnerable areas or in a crisis that is likely to be affected by human activities by studying the status of seagrass resources to explore the boundaries of each seagrass source types of seagrass and assessed the degree of integrity based on the percentage of seagrass cover classified fertility levels into 4 levels.

Complete means that seagrass cover is more than 75%
Good means that seagrass cover is 51% - 75%
Mediumis means that seagrass cover is 25% – 50%
Slightly means that seagrass cover is less than 25%

Due to various environmental factors such as the severity of wind waves sea floor desiccation and season. It has an important effect on the distribution of seagrass species and quantity in each area. Therefore, during each survey year. It was found that each seagrass source had a change (status) occurring in 3 characteristics are the change in the diffusion boundary (area), the type component and fertility levels (Percentage of seagrass cover), but because seagrass is a flowering plant. It can reproduce both asexually and sexually, making it possible to find seagrass growing in areas far from the original seagrass habitat. Comparison of data to know the trend of change. Only changes in diffusion boundaries are considered. Whether the seagrass area in each area has changed or not. Criteria for change must differ by more than 10% of the reference area, categorized into 4 cases: “more complete, stable, decreasing seasonally and deteriorating” by comparing changes with seagrass area data with existing seagrass areas. last year's survey To know the changes that may affect the ecosystem or cause changes in the ecosystem.

Assessment of changes in the seagrass area by comparing the current year's seagrass area with the previous year. The trend is defined into 4 types as follows :

1) More complete means the area increases more than 10%.

2) Stable means the area increases or decreases less than or equal to 10%.

3) Decreases seasonally means the area decreases. more than 10% from natural changes but not caused by human activities.

4) Deteriorated means the area has decreased by more than 10% caused by human activities.

Information: Marine Resources Research and Development Institute Coastal and Mangrove Forest
Date : 22 April 2022

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