Environmental limits of low salinity to Gracilaria gracilis development. Where do we draw the line?
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1
Instituto Politécnico de Leiria, MARE – Marine and Environmental Sciences Centre, Portugal
Macroalgae aquaculture correspond to 24% of the total produced species. Most reared species (93%) belong to the genus Porphyra (Nori), Gracilaria, Laminaria and Undaria, corresponding. Red macroalgae (Gracilariales, Rhodophyta) are important for industrial and biotechnological uses having a considerable economic importance. They are the main source of agar, the most valuable phycocolloid, worldwide. These compounds have a wide use in food medicine, cosmetics and food preparation such as in ice creams, jellies and soups. Also in recent years, the application of different algae species in aquaculture has become a research focus. It has been demonstrated that there are several beneficial effects of both micro and macroalgae as a dietary protein source of several fish species.
In this study, macroalgae were collected at Braço da Barosa (Óbidos Lagoon, center of the western coast of Portugal), transported to the laboratory, washed with water at the same conditions as the sampling place (20 psu) and maintained in water until the beginning of trials. Two experiments were conducted in order to evaluate the effects of salinity on Gracilaria gracilis growth. Both trials, were performed using Provasoli´s enriched solution (PES), photoperiod 12:12 and temperature was maintained at 20 ⁰C. Trial one, performed on Petri dishes, salinity values used were 0, 5, 10, 20 and 35 psu. Six plates per salinity were tested. Weekly growth was evaluate by measuring length during 44 days. Second experiment was performed on 4 trays. One as control and the other three as replicate. Twenty grams of G. gracilis were weighted and put in each tray. At the beginning salinity was 20 psu, and each week occurred a decrease, to 15, then to 10 and at the last week to 5 psu. This trial was performed during 21 days, and growth was evaluate by measuring the final weight (Wf). Results showed that G. gracilis had better growth rates on lower salinities, demonstrating that these are euryhaline marine organisms, with osmoregulation mechanisms.
Acknowledgements
This study had the support of Fundação para a Ciência e Tecnologia (FCT), through the strategic project UID/MAR/04292/2013 granted to MARE.
This project is being financed by Herdade dos Portos de Avis, Mora.
Keywords:
Gracilaria growth,
macroalgae rearing,
Red seaweeds,
salinity.,
Osmoregulation mechanisms
Conference:
IMMR | International Meeting on Marine Research 2016, Peniche, Portugal, 14 Jul - 15 Jul, 2016.
Presentation Type:
Poster presentation
Topic:
Aquaculture
Citation:
França
M,
Afonso
CN,
Baptista
TM,
Pombo
A and
Mouga
TM
(2016). Environmental limits of low salinity to Gracilaria gracilis development. Where do we draw the line?.
Front. Mar. Sci.
Conference Abstract:
IMMR | International Meeting on Marine Research 2016.
doi: 10.3389/conf.FMARS.2016.04.00029
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Received:
19 May 2016;
Published Online:
13 Jul 2016.
*
Correspondence:
Prof. Teresa M Mouga, Instituto Politécnico de Leiria, MARE – Marine and Environmental Sciences Centre, Peniche, 2520-641, Portugal, mougat@ipleiria.pt