IV LATIN AMERICAN CONGRESS OF ALGAE BIOTECHNOLOGY (CLABA) AND IV REDEALGAS WORKSHOP Temperature and salinity responses of drifting specimens of Kappaphycus alvarezii (Gigartinales, Rhodophyta) farmed on the Brazilian tropical coast Patrícia G. Araújo & Ana Lívia N. L. Ribeiro & Nair S. Yokoya & Mutue T. Fujii Received: 22 December 2013 /Revised and accepted: 21 March 2014 # Springer Science+Business Media Dordrecht 2014 Abstract Bioinvasion events causing serious environmental damage have been a concern with the mariculture of Kappaphycus alvarezii (Doty) Doty ex P.C. Silva, suggesting the importance of studying the biological aspects of drifting specimens of K. alvarezii for monitoring programs. The pres- ent study aims to evaluate the tolerance and growth of drifting color variants of K. alvarezii under different temperatures and salinities to determine their physiological capacity for grow- ing outside cultivation rafts. Drifting color variants were col- lected in Paraíba State, Brazil, in November 2011(dry month) and August 2012 (rainy month), and cultivated in the labora- tory under different temperatures (20, 24, 28, and 32 °C) and salinities (15, 25, 35, 45, and 55 psu). Growth rates as well as pigment and protein contents were determined. Results showed that drifting specimens collected in the dry month showed higher tolerance to variation in tem- perature (20 to 28 °C) and salinity (25 to 35 psu) than drifting specimens collected in the rainy month. Higher growth rates occurred in samples cultured at 20 and 24 °C (2.8–3 % day -1 ) and 25 to 35 psu (3.4–3.5 % day -1 ), suggest- ing temperature and salinity optima. Higher phycobiliprotein levels were observed in the red and brown variants under hypersaline conditions (45 and 55 psu). Higher chlorophyll a contents were associated with samples cultivated at 20– 24 °C and 24–35 psu. Based on the results of the present study, drifting specimens collected in dry month are more tolerant to temperature and salinity variations, suggesting that the drifting K. alvarezii should be monitored especially during this period to prevent its establishment outside the cultivation rafts and dispersion along the northeastern coast of Brazil. Keywords Kappaphycus alvarezii . Drifting color variants . Growth . Salinity . Temperature . Tolerance . Tropical waters Introduction Kappaphycus alvarezii (Doty) Doty ex P. Silva is an econom- ically important species and represents the main source of kappa carrageenan, a phycocolloid used in the food, pharma- ceutical, agricultural, and cosmetic industries. It is also a raw material for bioethanol production (Hurtado et al. 2013). Currently, K. alvarezii is a key species in aquaculture by its high biomass production, and because of this, it has been introduced in several tropical and subtropical countries for mariculture purposes (Hayashi et al. 2010). In Brazil, K. alvarezii was initially introduced in 1995, in São Paulo State, in the southeastern Brazilian coast, to evalu- ate its potential for commercial cultivation and its environ- mental impact (Paula et al. 1999). Afterwards, it was intro- duced in Santa Catarina, which is located on the southern coast of Brazil (Hayashi et al. 2011a ). Since 1998, K. alvarezii has been cultivated commercially in southeastern Rio de Janeiro State (Castelar et al. 2009). However, several studies have reported the potential for commer- cial cultivation, but also the possibility of remote inva- sion in the subtropical coastal waters of southeastern and southern Brazil (Paula et al. 1999, 2001, 2002; Bulboa and Paula 2005; Hayashi et al. 2011a; Bulboa et al. 2008; Castelar et al. 2009; Góes and Reis 2012). In the 2000s, K. alvarezii was introduced in the northeast- ern Brazil for mariculture purposes, and it has been farmed on a small scale by local fishermen in a region characterized by tropical waters. However, the potential risk of invasion of this exotic species continues to be a concern by the lack of bio- logical information about the introduction of K. alvarezii in P. G. Araújo : A. L. N. L. Ribeiro : N. S. Yokoya (*) : M. T. Fujii Instituto de Botânica, Secretaria do Meio Ambiente do Estado de São Paulo, Av. Miguel Estéfano, 3687, 04301-012 São Paulo, SP, Brazil e-mail: nyokoya@hotmail.com J Appl Phycol DOI 10.1007/s10811-014-0303-9