Diversity and Carbon Sequestration of Seaweed in the Ma’an Archipelago, China

Abstract

Seaweed communities perform a variety of ecological services, including primary productivity supply, biological habitat construction, water purification, and acting as marine carbon sinks. The abundance of seaweed is the basis for the assessment of ecological services in communities. The Ma’an Archipelago, adjacent to the Yangtze River estuary in China, is an important and typical island group. In this study, the abundance of seaweed in the typical coastal islands of the Ma’an Archipelago, Zhejiang Province, was evaluated by means of sonar detection and scuba diving sampling methods. The organic carbon content of six dominant seaweed species was measured to estimate the carbon sequestration capacity of the dominant species in the Ma’an Archipelago. The results show that 27 species of Rhodophyta, 10 species of Ochrophyta, and two species of Chlorophyta were found in the Ma’an Archipelago. Seaweed was distributed in the coastal areas of the islands, with a distribution width of 2–60 m. Gouqi Island had the longest shoreline, and there, the distribution depth of the seaweed reached 15 m and the area of the seaweed community was the largest. The slope of the rocks in the Sanheng survey area was large and the width of the seaweed community was small. The distribution area of seaweed in the Ma’an Archipelago was 6.51–13.43 km2 and the organic carbon content of the seaweed was 33.16 ± 3.26%. The biomass of Ochrophyta in the Ma’an Archipelago was the largest, followed by Chlorophyta and Rhodophyta. Among the six dominant species, the carbon sequestration of Sargassum thunbergii was the largest, at 277.91–848.74 t per year, and that of Undaria pinnatifida was the smallest. This study provides scientific guidance for the assessment of the primary productivity supply, carbon sink, and conservation capacity of seaweeds in China.

Satellite Imagery-Estimated Intertidal Seaweed Biomass Using UAV as an Intermediary

“…According to the conversion ratio of wet to dry weight, the ratio of dry to wet weight of Sargassum thunbergii is about 0.57 [45], and the ratio of dry to wet weight of Ulva pertusa is about 0.19 [46]. Based on this, it can be concluded that the dry weight of Gouqi Island intertidal Sargassum thunbergii is about 8.0 × 10 8 g, and the dry weight of Ulva pertusa is about 6.6 × 10 7 g. The carbon sequestration of Sargassum thunbergii accounts for approximately 0.30 of the dry weight, while Ulva pertusa accounts for approximately 0.29 of the dry weight [47]. Therefore, the carbon sequestration capacity of Gouqi Island intertidal Sargassum thunbergii is 2.4 × 10 8 g, and the carbon sequestration capacity of Ulva pertusa is 1.9 × 10 7 g. The satellite imaging time is in summer, during the maturation and decline period of the intertidal seaweed on Gouqi Island.…”