Forests of the giant kelp Macrocystis pyrifera found on coastal rocky reefs lack the large reservoirs for nutrient storage found in many terrestrial environments. Supporting their high year-round growth rates requires a continuous supply of nitrogen. Complementary timing of nutrient supply associated with the physical processes that deliver nitrate to reefs largely achieves this goal, but modeling studies indicate that the magnitude of nitrate delivery is inadequate to support the measured nitrogen demand of kelp forests during summer. Ammonium, from sediment efflux and excretion by reef consumers, likely fills the deficit. Together, the varied sources of inorganic nitrogen supplied to kelp forests support their high growth rates throughout the year. Kelp compensates for diminished nitrogen supply during summer by decreasing tissue nitrogen content, resulting in a doubling of kelp C:N ratios.
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Brzezinski, M.A., D.C. Reed, S. Harrer, A. Rassweiler, J.M. Melack, B.M. Goodridge, and J.E. Dugan. 2013. Multiple sources and forms of nitrogen sustain year-round kelp growth on the inner continental shelf of the Santa Barbara Channel. Oceanography 26(3):114–123, https://doi.org/10.5670/oceanog.2013.53.
Allgeier, J.E., L.A. Yeager, and C.A. Layman. 2013. Consumers regulate nutrient limitation regimes and primary production in seagrass ecosystems. Ecology 94:521–529, https://doi.org/10.1890/12-1122.1.
Bray, R.N., A.C. Miller, S. Johnson, P.R. Krause, L. Robertson, and A.M. Westcott. 1988. Ammonium excretion by invertebrates and fishes on a subtidal rocky reef in southern California. Marine Biology 100:21–30, https://doi.org/10.1007/BF00392951.
Brown, M.T., M.A. Nyman, J.A. Keogh, and N.K.M. Chin. 1997. Seasonal growth of the giant kelp Macrocystis pyrifera in New Zealand. Marine Biology 127:417–424, https://doi.org/10.1007/s002270050182.
Brzezinski, M.A., and L. Washburn. 2011. Phytoplankton primary productivity in the Santa Barbara Channel: Effects of wind-driven upwelling and mesoscale eddies. Journal of Geophysical Research 116, C12013, https://doi.org/10.1029/2011JC007397.
Burkepile, D.E., J.E. Allgeier, A.A. Shantz, C.E. Pritchard, N.P. Lemoine, L.H. Bhatti, and C.A. Layman. 2013. Nutrient supply from fishes facilitates macroalgae and suppresses corals in a Caribbean coral reef ecosystem. Scientific Reports 3:1,493, https://doi.org/10.1038/srep01493.
Clendenning, K.A. 1971. Photosynthesis and general development. Pages 169–190 in The Biology of Giant Kelp Beds (Macrocystis) in California. W.J. North, ed., Beihefte Zur Nova Hedwigia, Verlag Von J. Cramer, Lehre, Germany.
Dugan, J.E., D.M. Hubbard, M. McCrary, and M. Pierson. 2003. The response of macrofauna communities and shorebirds to macrophyte wrack subsidies on exposed sandy beaches of southern California. Estuarine Coastal and Shelf Science 58S:133–148, https://doi.org/10.1016/S0272-7714(03)00045-3.
Dugan, J.E., D.M. Hubbard, H.M. Page, and J. Schimel. 2011. Marine macrophyte wrack inputs and dissolved nutrients in beach sands. Estuaries and Coasts 34(4):839–850, https://doi.org/10.1007/s12237-011-9375-9.
Eppley, R.W., and B.J. Peterson. 1979. Particulate organic matter flux and planktonic new production in the deep ocean. Nature 282:677–680, https://doi.org/10.1038/282677a0.
Fram, J.P., H.L. Stewart, M.A. Brzezinski, B. Gaylord, D.C. Reed, S.L. Williams, and S. MacIntyre. 2008. Physical pathways and utilization of nitrate supply to the giant kelp, Macrocystis pyrifera. Limnology and Oceanography 53:1,589–1,603, https://doi.org/10.4319/lo.2008.53.4.1589.
Gaylord, B., J.H. Rosman, D.C. Reed, J.R. Koeseff, J. Fram, S. MacIntyre, K. Arkema, C. McDonald, M.A. Brzezinski, J.L. Largier, and others. 2007. Spatial patterns of flow and their modification within and around a giant kelp forest. Limnology and Oceanography 52:1,838–1,852, https://doi.org/10.4319/lo.2007.52.5.1838.
Gerard, V.A. 1976. Some aspects of material dynamics and energy flow in a kelp forest in Monterey Bay, California. PhD Dissertation, University of California, Santa Cruz, CA.
Gerard, V.A. 1982a. Growth and utilization of internal nitrogen reserves by the giant kelp Macrocystis pyrifera in a low-nitrogen environment. Marine Biology 66:27–35, https://doi.org/10.1007/BF00397251.
Gerard, V.A. 1982b. In situ rates of nitrate uptake by giant kelp, Macrocystis pyrifera (L.) C. Agardh: Tissue differences, environmental effects, and predictions of nitrogen-limited growth. Journal of Experimental Marine Biology and Ecology 62(3):21l–224, https://doi.org/10.1016/0022-0981(82)90202-7.
Goodman, J., M.A. Brzezinski, E.R. Halewood, and C.A. Carlson. 2012. Sources of phytoplankton to the inner continental shelf in the Santa Barbara Channel inferred from cross-shelf gradients in biological, physical and chemical parameters. Continental Shelf Research 48(1):27–39, https://doi.org/10.1016/j.csr.2012.08.011.
Goodridge, B.M., and J.M. Melack. 2012. Land use control of stream nitrate concentrations in mountainous coastal California watersheds. Journal of Geophysical Research 117, G02005, https://doi.org/10.1029/2011JG001833.
Graham, M.H., J.A. Vasquez, and A.H. Buschmann.
2007. Global ecology of the giant kelp Macrocystis: From ecotypes to ecosystems. Pp. 39–88 in Oceanography and Marine Biology: An Annual Review, vol 45. R.N. Gibson, R.J.A. Atkinson, and J.D.M. Gordon, eds, CRC Press.
Griffiths, C.L., and J. Stenton-Dozey. 1981. The fauna and rate of degradation of stranded kelp. Estuarine, Coastal and Shelf Science 12:645–653, https://doi.org/10.1016/S0302-3524(81)80062-X.
Haines, K.C., and P.A. Wheeler. 1978. Ammonium and nitrate uptake by the marine macrophytes Hypnea musciformis (Rhodophyta) and Macrocystis pyrifera (Phaeophyta). Journal of Phycology 14:319–324.
Hayes, W.B. 1974. Sand-beach energetics: Importance of the isopod Tylos punctatus. Ecology 55(4):838–847, https://doi.org/10.2307/1934419.
Holbrook, S.J., A.J. Brooks, R.J. Schmitt, and H.L. Stewart. 2008. Effects of sheltering fish on growth of their host corals. Marine Biology 155:521–530, https://doi.org/10.1007/s00227-008-1051-7.
Koop, K., R.C. Newell, and M.I. Lucas. 1982. Microbial regeneration of nutrients from the decomposition of macrophyte debris on the shore. Marine Ecology Progress Series 9:91–96.
Lastra, M., H.M. Page, J.E. Dugan, D.M. Hubbard, and I.F. Rodil. 2008. Processing of allochthonous macrophyte subsidies by sandy beach consumers: Estimates of feeding rates and impacts on food resources. Marine Biology 154:163–174, https://doi.org/10.1007/s00227-008-0913-3.
Mann, K.H. 2000. Ecology of Coastal Waters: With Implications for Management, 2nd ed. Wiley-Blackwell, 406 pp.
McPhee-Shaw, E., D.A. Siegel, L. Washburn, M.A. Brzezinski, J.L. Jones, A. Leydecker, and J. Melack. 2007. Mechanisms for nutrient delivery to the inner shelf: Observations from the Santa Barbara Channel. Limnology and Oceanography 52:1,748–1,766, https://doi.org/10.4319/lo.2007.52.5.1748.
Page, H.M., D.C. Reed, M.A. Brzezinski, J. Melack, and J.E. Dugan. 2008. Assessing the importance of land and marine sources of organic matter to kelp forest food webs. Marine Ecology Progress Series 360:47–62, https://doi.org/10.3354/meps07382.
Rassweiler, A., K.K. Arkema, D.C. Reed, M.A. Brzezinski, and R.C. Zimmerman. 2008. Net primary production, growth and standing crop of Macrocystis pyrifera in southern California. Ecology 89:2,068, https://doi.org/10.1890/07-1109.1.
Reed, D.C., and M.A. Brzezinski. 2009. Kelp forests. Pp. 30–37 in The Management of Natural Coastal Carbon Sinks. D.d’A. Laffoley and G. Grimsditch, eds, IUCN, Gland, Switzerland.
Reed, D.C., A. Rassweiler, and K.K. Arkema. 2008. Biomass rather than growth rate determines variation in net primary production by giant kelp. Ecology 89:2,493–2,505.
Rysgaard, S., P.B. Christensen, and L.P. Nielsen. 1995. Seasonal variation in nitrification and denitrification in estuarine sediment colonized by benthic mircroalgae and bioturbating infauna. Marine Ecology Progress Series 126:111–112, https://doi.org/10.3354/meps126111.
Stewart, H.L., J.P. Fram, D.C. Reed, S.L. Williams, M.A. Brzezinski, S. MacIntyre, and B. Gaylord. 2009. Differences in growth, morphology and tissue carbon and nitrogen of Macrocystis pyrifera within and at the outer edge of a giant kelp forest in California, USA. Marine Ecology Progress Series 375:101–112, https://doi.org/10.3354/meps07752.
Swarzenski, P.W., and J.A. Izbicki. 2009. Coastal groundwater dynamics off Santa Barbara, California: Combining geochemical tracers, electromagnetic seepmeters, and electrical resistivity. Estuarine, Coastal and Shelf Science 83:77–89, https://doi.org/10.1016/j.ecss.2009.03.027.
Thornton, D.C.O., G.J.C. Underwood, and D.B. Nedwell. 1999. Effect of illumination and emersion period on the exchange of ammonium across the estuarine sediment-water interface. Marine Ecology Progress Series 184:21–29, https://doi.org/10.3354/meps184011.
van Tüssenbroek, B.I. 1993. Plant and frond dynamics of the giant kelp, Macrocystis pyrifera, forming a fringing zone in the Falkland Islands. European Journal of Phycology 28:161–165, https://doi.org/10.1080/09670269300650251.
Washburn, L., and E. McPhee-Shaw. 2013. Coastal transport processes affecting inner-shelf ecosystems in the California Current System. Oceanography 26(3):34–43, https://doi.org/10.5670/oceanog.2013.43.
Wheeler, P.A., and W.J. North. 1981. Nitrogen supply, tissue composition, and frond growth rates for Macrocystis pyrifera off the coast of southern California. Marine Biology 64:59–69, https://doi.org/10.1007/BF00394081.
Zimmerman, R.C., and J.N. Kremer. 1984. Episodic nutrient supply to a kelp forest ecosystem in Southern California. Journal of Marine Research 42:605–632, https://doi.org/10.1357/002224084788506031.
Zimmerman, R.C., and J.N. Kremer. 1986. In situ growth and chemical composition of the giant kelp, Macrocystis pyrifera: Response to temporal changes in ambient nutrient availability. Marine Ecology Progress Series 27:277–285.
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