Limited evolutionary responses to harvesting regime in the intensive production of algae
- 234 Downloads
Plastic changes in the growth and productivity of algae in response to environment and stocking density are well established. In contrast, the capacity for such changes to persist once environmental differences cease, potentially signalling an evolutionary response, have rarely been tested for algae in intensive production systems. We tested whether continuous differences in harvesting regime (a high stocking density/low-yield regime versus low stocking density/high-yield regime) generated changes in biomass productivity and other growth metrics within several strains of the clonal macroalga Oedogonium (Chlorophyta, Oedogoniales) and whether such changes persisted once differential harvesting yields ceased. We found considerable plasticity in growth rate and biomass productivity over a 12-week period of active selection (i.e. repeated high-yield and low-yield harvesting of clonal lineages within strains) and that strains responded differently to this selection pressure over time. While small, but significant, differences in growth rates of clonal lineages exposed to high-yield vs low-yield harvesting regimes were maintained after prolonged culture under a common selection regime (i.e. medium-yield harvesting), differences in biomass productivity were not. There was no evidence for positive or negative effects of maintaining multiple strains in polyculture on growth and biomass productivity. Overall, we detected limited potential for evolutionary responses to harvesting regime in the main commercial trait of interest—biomass productivity. This outcome is important for commercial cultivation in intensive production systems, since it identifies a low risk that harvesting practices will impact negatively on biomass productivity in the longer term.
KeywordsAquaculture Oedogonium Chlorophyceae Growth Selection Polyculture Monoculture
We thank M. Martinez, T. Mannering, N. Neveux and T. Carl for assistance with experiments. We thank S. Skinner for the morphological identification of O. intermedium and R. de Nys and two anonymous reviewers for providing comments on the manuscript. This project was supported by MBD Energy Ltd. The sponsors had no involvement in study design; in the collection, analysis and interpretation of data; in the writing of the report and in the decision to submit the article for publication.
- Borowitzka LJ, Borowitzka MA (1990) Commercial production of β-carotene by Dunaliella salina in open ponds. Bull Mar Sci 47:244–252Google Scholar
- de Castro AS, Garcia VMT (2005) Growth and biochemical composition of the diatom Chaetoceros cf. wighamii brightwell under different temperature, salinity and carbon dioxide levels. I. Protein, carbohydrates and lipids. Aquaculture 246:405–412Google Scholar
- Edeline E, Carlson SM, Stige LC, Winfield IJ, Fletcher JM, James JB, Haugen TO, Vøllestad LA, Stenseth NC (2007) Trait changes in a harvested population are driven by a dynamic tug-of-war between natural and harvest selection. Proc Nat Acad Sci 104:15799–15804CrossRefPubMedPubMedCentralGoogle Scholar
- Entwisle TJ, Skinner S, Lewis SH, Foard HJ (2007) Algae of Australia: Batrachospermales, Thoreales, Oedogoniales and Zygnemaceae. CSIRO Publishing/Australian Biological Resources Study Collingwood, AustraliaGoogle Scholar
- Garland T Jr, Rose MR (2009) Experimental evolution: concepts, methods and applications of selection experiments. University of California PressGoogle Scholar
- Guillemin M-L, Faugeron S, Destombe C, Viard F, Correa JA, Valero M (2008) Genetic variation in wild and cultivated populations of the haploid–diploid red alga Gracilaria chilensis: how farming practices favor asexual reproduction and heterozygosity. Evolution 62:1500–1519CrossRefPubMedGoogle Scholar
- Hendry AP, Kinnison MT, Heino M, Day T, Smith TB, Fitt G, Bergstrom CT, Oakeshott J, Jørgensen PS, Zalucki MP, Gilchrist G, Southerton S, Sih A, Strauss S, Denison RF, Carroll SP (2011) Evolutionary principles and their practical application. Evol Appl 4:159–183CrossRefPubMedPubMedCentralGoogle Scholar
- Littell RC, Milliken GA, Stroup WW, Wolfinger RD, Schabenberger O (2006) SAS for mixed models. SAS Institute Inc., Cary, U.S.A.Google Scholar
- Poore AGB, Fagerström T (2000) Intraclonal variation in macroalgae: causes and evolutionary consequences. Selection 1:123–134Google Scholar