Biodiversity, Density, Distribution Patterns and Cell Structure of Algae in Manado Bay

The results of study on the diversity of algae species at five stations in Manado Bay showed that the number of algae reached 4254 individuals per research station. The average density was 284 ind/m2. There are 23 species of macroalgae found in Manado Bay, namely Chlorophyta (10 species), Rhodophyta (7 species) and Phaeophyta (6 species). The species are Padina pavonica, P. australis, Turbinaria ornate, T. decurrens, Sargassum polycystum, Dictyota dichotoma, Gracilaria Salicornia, G edulis, Eucheuma denticulatum, Amphiroa fragilissima, Acetabularia dentata, Bornetella oligospora, Ulvase, C. lactuta, U. intestinalis, Actinotrichia fragilia and Chaetomorpha crassa.

The diversity of algae species (H') in Manado Bay is 2.41. This indicates that the diversity of algae species in Manado Bay is moderate and the condition of the community is moderate, which is no overall extreme ecological pressure in the waters. Waters condition  is stable with an evenness index value (E) of 0.77. No species dominates the waters, although Acetabulria dentata has the highest number of individuals reaching 1148 individuals at station 1, but the moderate dominance index with a value of C = 0.557 is still in the medium category value range (C = 0.50- 0.75). The results of overall dominance index of Manado bay waters are low (C = 0.270), which means that no algae species dominate in Manado Bay. The distribution pattern of algae species in Manado Bay is random and clustered. The clumping pattern is one of the algae's strategies to avoid predators, an effort to maintain the existence of their species in nature so that they continue to exist in nature. Water conditions, especially water quality, such as pH, salinity and water temperature are still in the range suitable for algae growth. Algal cell structure is eukaryotic.