Effect of Growth of Filamentous Algae on the Thallus Surface of Kappaphycus alvarezii (Doty) L.M.Liao (Rhodophyta)

Filamentous algae usually form dense or sparse masses that float freely or attach to other plants, rocks, or other hard substrates. Many filamentous algae attach to Kappaphycus alvarezii which is cultivated by farmers in the tropics. This study explained the effect of filamentous algae attachment on the morphology and growth of K. alvarezii. This research was conducted in one of the cultivation locations on the coast of Tanjung Tiram, southeast Sulawesi Province, Indonesia. This study used a vertical net to cultivate K. alvarezii thallus samples. Vertical nets are used to protect K. alvarezii from fish pests and attached algae. We analyze the attachment rate of filamentous algae about the morphology and growth of K. alvarezii thallus within 40 days. The results showed two dominant filamentous algae species, Elachista flaccida and Chaetomorpha crassa. The density of E. flaccida occurred on day 10, with a density level reaching 12 individuals/m2 and increasing on day 20 to 45 individuals/m2. Chaetomorpha crassa species also appeared at 2.24 g/m2 on day 20, decreased to 0.63 g/m2 on day 30, and disappeared on day 40. The torn surface thallus was seen to occur on day 2.324 mm2 on day ten and decreased by 104 mm2 on day 20. Attachment of filamentous algae slightly impacted the growth of K. alvarezii thallus, although the correlation analysis did not show a significant effect. Another correlation analysis explained no significant correlation between multiple attachments of filamentous algae and torn surface thallus of K. alvarezii.