J Appl Phycol (2009) 21:265–272 DOI 10.1007/s10811-008-9360-2 Seasonal changes in growth rate, carrageenan yield and lectin content in the red alga Kappaphycus alvarezii cultivated in Camranh Bay, Vietnam Le Dinh Hung & Kanji Hori & Huynh Quang Nang & Tran Kha & Le Thi Hoa Received: 14 April 2008 / Revised and accepted: 26 May 2008 / Published online: August 2008 # Springer Science + Business Media B.V 2008 Abstract The three color morphotypes of the red alga Kappaphycus alvarezii (brown, red and green) were cultured in Camranh Bay, Vietnam, using the fixed offbottom monoline culture method to evaluate the growth rate, carrageenan yield, 3,6-anhydrogalactose, gel strength and lectin content The brown morphotype was cultivated over a 12-month period; the red and green morphotypes were over a 6-month period At the 60-day culture timepoint, the brown morphotype showed a higher growth rate (3.5–4.6% day−1) from September to February, and lower growth rate (1.6–2.8% day−1) from March to August Significant (P