Marine isoscapes

Isotopic maps, or isoscapes, are used to describe the spatial patterns in the stable isotope values of organisms, usually those at the base of the food webs such as phytoplankton and zooplankton, hereafter called baseline organisms. Isoscapes are useful to study the trophic and spatial ecology of high trophic-level animals, such as sharks, marine turtles, seabirds, whales and dolphins. The isotopic values of baseline organisms are affected by the oceanographic conditions in that ecosystem, such as temperature, nutrient concentration and productivity levels. Since different marine ecosystems are subject to different oceanographic conditions, the isotopic values of baseline organisms are expected to vary through space and time. Consequently, if we want to apply the stable isotope methodology to assess a predators' feeding habit and foraging area, it is essential that we develop isotopic maps that describe how the isotopic values of baseline organisms vary through space.

related research

oceanic waters of the south atlantic

In this work, I analysed carbon and nitrogen stable isotopes in zooplankton to describe the patterns in isotopic variability at the base of the food webs along the oceanic waters of the western South Atlantic. The paper related to this work is published in the journal Deep Sea Research Part I, and can be accessed here.

key references

Graham, B.S., Koch, P.L., Newsome, S.D., McMahon, K.W., Aurioles, D., 2010. Using Isoscapes to Trace the Movements and Foraging Behavior of Top Predators in Oceanic Ecosystems. In: West, J.B., Bowen, G.J., Dawson, T.E., Tu, P.K. (Eds.), Isoscapes: Understanding Movement, Pattern, and Process on Earth through Isotope Mapping, pp. 299–318.

Magozzi, S., Yool, A., Vander Zanden, H.B., Wunder, M.B., Trueman, C.N., 2017. Using ocean models to predict spatial and temporal variation in marine carbon isotopes. Ecosphere. 8(5), e01763.

McMahon, K.W., Hamady, L.L., Thorrold, S.R., 2013. A review of ecogeochemistry approaches to estimating movements of marine animals. Limnol. Oceanogr. 58, 697–714. doi: 10.4319/lo.2013.58.2.0697.

Newsome, S.D., Clementz, M.T., Koch, P.L., 2010. Using stable isotope biochemistry to study marine mammal ecology. Mar. Mamm. Sci. 26, 509-572.

Post, D.M., 2002. Using stable isotopes to estimate trophic position: Models, methods and assumptions. Ecology 83(3), 703-718.

Trueman, C.N., Glew, K.S.J., 2019. Isotopic tracking of marine animal movement. In: Hobson, K.A., Wassenaar, L.I. (Eds.), Tracking animal migration with stable isotopes, pp. 137-172.