Biobanking of local seaweed species to support conservation and commercial aquaculture: Saccharina latissima at its southern distribution limit.
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1
Interdisciplinary Center for Marine and Environmental Research, Abel Salazar Institute of Biomedical Sciences, University of Porto, Portugal
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2
Faculty of Sciences, University of Porto, Portugal
Interest in seaweed has been rising due to the multiple high value applications of their biomass. They are considered a healthy food, due to a balanced nutritional composition, and a valuable source of bioactive compounds for the food, feed, cosmetic and pharmaceutical industries. Additionally, seaweed is used for nutrient bioremediation and is also considered a good candidate for biofuels production.
Since at present seaweed production in Europe is originated mainly from harvest, an increased demand may cause the overexploitation of natural populations that are already under stress by global climate change and anthropogenic pressures. In order to fulfil this increasing biomass demand, sustainable seaweed aquaculture methods are needed to avoid the risk of overexploitation of wild stocks. These methods include the implementation of breeding strategies based on strain selection and improvement for cultivation.
Natural populations are a repository of genetic diversity which plays a fundamental role in their adaptation to changing environmental conditions. This genetic diversity may also be an important source of genetic material for the selection of strains that present interesting traits for commercial or conservation aquaculture. Traits useful for commercial aquaculture include high growth rates, resistance to herbivory and adaptation to the environmental variability of the cultivation site, whereas traits such as reproductive output are important for conservation aquaculture. Natural populations at the rear edges - the low-latitude limit of species ranges - are recognized as particularly vulnerable areas of diversification and endemism. They often have unique genetic diversity which may hold valuable genetic traits important for conservation and sustainable seaweed aquaculture development.
In the framework of the GENIALG project, strains of Saccharina latissima, a kelp with high commercial potential, were collected from populations of northern Portugal and Galicia (northern Spain) for the establishment of a local biobank. Biometric data corresponding to each strain were also collected. These populations are at the southern distribution limit of the species in the western Atlantic coast. The site in Portugal is Amorosa (41.641867°N; -8.823398°W), the southernmost site where S. latissima can be found attached to pebbles that appear in the intertidal. This population is very dispersed and dynamic, since all the individuals found are attached to pebbles that are mobile with the currents and wave action. In Galicia, the site is located in the Ría de Muros y Noya, near Esteiros (42.786667N; -8.966111W), characterised by more sheltered conditions, compared to the Amorosa shore which is a very exposed area.
Strains were collected at Amorosa in several sampling periods (between March 2017 and March 2018), whereas the population in Galicia was sampled in February 2019. For each individual, the biometric data collected were: total length, stipe length, blade and stipe width, meristem and blade thickness, blade area and sori area. For the fertile ones, samples from the reproductive tissue were collected for spore release, which were placed in Petri dishes at 15 ºC under red light to avoid fertility. Tissue samples were also collected for genotyping. Presently, the biobank includes 44 strains of the Amorosa population and 25 of the Esteiros population.
Considering the Amorosa population, fertile individuals were found from November to March, the typical reproductive season of cold water kelp species. The largest individuals, reaching 133 cm, were found in September, decreasing in the following sampling dates. These data, although limited, indicate that spores are released during the winter, growth occurs during the spring and summer, and in autumn size decreases due to blade erosion when they become reproductive. In March some mature individuals presented a constriction separating the old from a new blade, indicating that the growing season starts in early spring. Considering the reproductive effort, measured by the percent sori to blade area and number of spores per cm2, no obvious trend was observed although the highest values were found in February. Comparing the Esteiros population biometric data with data from the Amorosa population of the same period, it is apparent that sporophytes from the Galician population are larger, with longer and wider blades. This may be related to adaptation to environmental conditions, especially hydrodynamics, since the Galician site presents more sheltered conditions than the Portuguese site, influencing blade morphology.
The on-going genotyping of the strains included in this biobank will allow assessment of the genetic diversity in these range-edge populations. Future work will include the study of the influence of environmental conditions on phenotypic traits and their relationship with genotypes. The establishment and development of this local biobank for S. latissima will be useful for development of sustainable aquaculture methods with improved strains, better adapted to local conditions and also for supporting conservation actions in local kelp beds.
Acknowledgements
This work was funded by the project Genialg - GENetic diversity exploitation for Innovative macro-ALGal biorefinery, EC Grant agreement no: 727892, supported by the European Union Horizon 2020 Framework Programme for Research and Innovation (2014-2020)
Keywords:
Saccharina latissima,
biobanking,
Distribution limits,
Aquaculture,
kelp forests
Conference:
XX Iberian Symposium on Marine Biology Studies (SIEBM XX) , Braga, Portugal, 9 Sep - 12 Sep, 2019.
Presentation Type:
Poster Presentation
Topic:
Fisheries, Aquaculture and Biotechnology
Citation:
Azevedo
IC,
Melo
R and
Pinto
IS
(2019). Biobanking of local seaweed species to support conservation and commercial aquaculture: Saccharina latissima at its southern distribution limit..
Front. Mar. Sci.
Conference Abstract:
XX Iberian Symposium on Marine Biology Studies (SIEBM XX) .
doi: 10.3389/conf.fmars.2019.08.00176
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Received:
14 May 2019;
Published Online:
27 Sep 2019.
*
Correspondence:
Dr. Isabel C Azevedo, Interdisciplinary Center for Marine and Environmental Research, Abel Salazar Institute of Biomedical Sciences, University of Porto, Matosinhos, Portugal, isabel.costa.azevedo@gmail.com
Mx. Rosa Melo, Interdisciplinary Center for Marine and Environmental Research, Abel Salazar Institute of Biomedical Sciences, University of Porto, Matosinhos, Portugal, rmelo@ciimar.up.pt