Local adaptation to ocean warming and acidification in giant kelp (Macrocystis pyrifera) reproduction
Jordan A. Hollarsmith[1,2]*, Alejandro Buschmann[3], Carolina Camus Torres[3], and Edwin D. Grosholz[1,2]
1 – Bodega Marine Laboratory, University of California, Davis
2 – University of California, Davis.
3 – Instituto Marino, Universidad de Los Lagos, Chile
Understanding how climate change may influence ecosystems depends substantially on its effects on foundation species. The giant kelp (Macrocystis pyrifera), is an iconic and widespread marine foundation species that provides critical food and habitat for ecologically and economically important nearshore communities. The potential for local adaptation in this species is poorly understood despite its broad distribution along strong pH and temperature gradients and strong barriers to dispersal. To test this possibility, we exposed giant kelp early life stages sourced from genetically disparate populations – three in California and four in Chile – to two temperatures and pH levels representing the range of in situ conditions experienced in each hemisphere in fully factorial common garden experiments. We observed high resistance at the haploid life stage across treatments and populations with developmental bottlenecks appearing at the egg production and sporophyte production stages. Populations from strong upwelling zones produced more eggs per female in low-pH conditions which could increase fertilization success. Only populations from southern and central California reached the diploid life stage under high-temperature conditions suggesting a greater vulnerability to climate- or ENSO-driven warming events among Southern Hemisphere and high-latitude Northern Hemisphere populations. This is the first study to explicitly test for population-level differences in giant kelp reproductive response to environmental change and the only to test such a wide latitudinal gradient. Results have important implications for understanding and modeling the future range shifts of this important foundation species under a changing climate with projected declines in ocean pH and increases in ocean temperature.
This work was made possible by generous grants from the National Science Foundation Graduate Research Opportunities Worldwide fellowship, the Explorer’s Club Fund for Exploration, the Point Reyes National Marine Sanctuary Neubacher Fund, the University of California-Davis Henry A. Jastro Research Fellowship, and the Comisión Nacional de Investigación Científica y Tecnológica (Chile).
It also was made possible by Kristen Elsmore, Katie Dubois, and Mike Doane for their assistance with field collections in California; Robinson Altamirano and José Luis Kappes for their field assistance in Chile; Chad Martin, Mariah Dorado, Aanisah Martin, Priya Shukla, Tallulah Winquist, and Haley Stott for their laboratory assistance in BML; and Karina Villegas and Cristian Vera for their laboratory assistance in I-Mar.
Jordan A. Hollarsmith[1,2]*, Alejandro Buschmann[3], Carolina Camus Torres[3], and Edwin D. Grosholz[1,2]
1 – Bodega Marine Laboratory, University of California, Davis
2 – University of California, Davis.
3 – Instituto Marino, Universidad de Los Lagos, Chile
Understanding how climate change may influence ecosystems depends substantially on its effects on foundation species. The giant kelp (Macrocystis pyrifera), is an iconic and widespread marine foundation species that provides critical food and habitat for ecologically and economically important nearshore communities. The potential for local adaptation in this species is poorly understood despite its broad distribution along strong pH and temperature gradients and strong barriers to dispersal. To test this possibility, we exposed giant kelp early life stages sourced from genetically disparate populations – three in California and four in Chile – to two temperatures and pH levels representing the range of in situ conditions experienced in each hemisphere in fully factorial common garden experiments. We observed high resistance at the haploid life stage across treatments and populations with developmental bottlenecks appearing at the egg production and sporophyte production stages. Populations from strong upwelling zones produced more eggs per female in low-pH conditions which could increase fertilization success. Only populations from southern and central California reached the diploid life stage under high-temperature conditions suggesting a greater vulnerability to climate- or ENSO-driven warming events among Southern Hemisphere and high-latitude Northern Hemisphere populations. This is the first study to explicitly test for population-level differences in giant kelp reproductive response to environmental change and the only to test such a wide latitudinal gradient. Results have important implications for understanding and modeling the future range shifts of this important foundation species under a changing climate with projected declines in ocean pH and increases in ocean temperature.
This work was made possible by generous grants from the National Science Foundation Graduate Research Opportunities Worldwide fellowship, the Explorer’s Club Fund for Exploration, the Point Reyes National Marine Sanctuary Neubacher Fund, the University of California-Davis Henry A. Jastro Research Fellowship, and the Comisión Nacional de Investigación Científica y Tecnológica (Chile).
It also was made possible by Kristen Elsmore, Katie Dubois, and Mike Doane for their assistance with field collections in California; Robinson Altamirano and José Luis Kappes for their field assistance in Chile; Chad Martin, Mariah Dorado, Aanisah Martin, Priya Shukla, Tallulah Winquist, and Haley Stott for their laboratory assistance in BML; and Karina Villegas and Cristian Vera for their laboratory assistance in I-Mar.
