Abstract:
Southern coastal zone acts as a highly productive ecosystem with rich macroalgae
diversity. However, limited scientific studies have been conducted on macroalgae
diversity in the southern coastal belt of Sri Lanka. The current study is focused on the
assessment of the intertidal, macroalgae diversity along this coastal belt. This study was
conducted using systematic sampling technique along the intertidal zone at 12 selected
regional coasts (Hambantota, Godawaya, Rekawa, Tangalle, Dickwella, Polhena, Mirissa,
Weligama, Unawatuna, Galle Fort, Dodanduwa and Hikkaduwa) representing three
districts (Hambantota, Matara, Galle) of the southern province during NE monsoon period
(December 2019 to February 2020). NE monsoon period was selected to minimize the
climatic effects during sampling in different seasons. Macroalgae species were
taxonomically identified using the recommended pictorial guides and literature records.
Oneway Analysis of Variance (ANOVA) was employed to identify the variations of
macroalgae diversity with sampling location (p<0.05). According to the results, a total of
26 macroalgae species (10 belong to Chlorophyta: >38% richness, 10 in Rhodophyta:
>38% richness, and 6 from Phaeophyta: >23 % richness) were identified in this coastal
belt. Ecologically dominant species belong to division Chlorophyta out of all the
sampling sites. Shannon-Wiener biodiversity index (H') of the macroalgae in respective
ecosystems significantly changed with sampling locations (p<0.05). The spatial variation
pattern of biodiversity is correlated with unsustainable anthropogenic activities and
natural factors. Shannon-Wiener biodiversity index (H') ranged at 0.67-2.59 in the study
sites. The highest composition of macroalgal species (20) was recorded from the
Godawaya site due to the minimum anthropogenic effect. Mirissa (02) and Dodanduwa
(01) regions had the lowest macroalgae species richness and commercial activities were
relatively higher along these coastal zones compared to all other sites. Accordingly,
macroalgae act as the biological indicators reflecting the health status of respective
ecosystems. So, the findings of this study would be important to identify the quality of the
coastal zones and apply appropriate coastal conservation and management measures in
the future. Also, the commonly recorded macroalgae species which belong to Chlorophyta
and Rhodophyta can be sustainably utilized in processing value-added foods and other
products. In conclusion, this study reveals the current status of macroalgae diversity on
the southern coast during the NE monsoon period and detailed investigation of species
composition is strongly recommended throughout the year.
Keywords: Biodiversity assessment, North east monsoon, Macroalgae, Intertidal zone,
Coastal ecosystems
