Research themes: Spatial ecology

Seagrass meadows, kelp forests, and oyster reefs form the foundation of many marine and estuarine ecosystems worldwide by creating habitat for numerous valuable species of fish and shellfish, forming an important food source for resident and migratory animals, and changing the physical and chemical conditions of the coastal ocean. Ecological theory predicts that spatial structure of these habitats—such as their size, shape, arrangement, and isolation—influences population, community, and ecosystem processes. Much of our work focuses on resolving the causes and consequences of these spatial dynamics across scales in space and time.

Key findings

Connectivity is key for local and regional metapopulation dynamics

  • Theory predicts that dispersal and connectivity among spatially structured populations can strongly influence the dynamics of both local populations and the overall population network, or metapopulation.

  • In metapopulations of giant kelp, increasing connectivity diminishes the risk of local extinction, enhances stability, and improves the likelihood of subsequent colonization, and patch area mediates this effect (Castorani et al. 2015, Iwaniec et al. 2021). 

  • Ignoring fluctuations in population fecundity can lead to overestimation of connectivity and persistence because fluctuations in fecundity, rather than dispersal, are the dominant driver of demographic connectivity and a key determinant of local extinctions and colonizations of giant kelp (Castorani et al. 2017). 

Resistance and resilience to marine heatwaves is geographically variable

  • Ocean heatwaves are increasing in frequency and duration in response to global climate trends.
  • The loss and subsequent recovery of giant kelp populations under extreme ocean warming varies strongly across space (Cavanaugh et al. 2019). Regions experiencing longer, hotter heatwaves are more susceptible to catastrophic declines, but recovery not related to temperature.

Disturbance maintains spatial coexistence through a competition-colonization trade-off

  • Theory predicts that disturbance can facilitate coexistence between species competing for limited resources.

  • In field surveys and experiments, disturbance to competitively-dominant, short-dispersing seagrass enhances spatial coexistence with competitively-inferior, broad-dispersing burrowing shrimp (Castorani et al. 2014).
  • In population models, disturbance size and frequency interact to structure coexistence through the spatial storage effect (Castorani & Baskett 2020). Supporting theory, intermediate disturbance enhances biodiversity.
  •  Hence, disturbance size, frequency, and their interaction can mediate landscape-scale biodiversity by altering the duration of time over which inferior competitors can escape competitive exclusion.

Related publications:

  • Cheng, S.L., M.R. Cornish, S. Hardison, R.S. Smith, K.N. Tedford, and M.C.N. Castorani. 2022. Coastal vegetation and bathymetry influence blue crab abundance across spatial scales. Estuaries and Coasts 45:1701–1715. [PDF]

  • Castorani, M.C.N., T.W. Bell, J.A. Walter, D.C. Reuman, K.C. Cavanaugh, and L.W. Sheppard. 2022. Disturbance and nutrients synchronise kelp forests across scales through interacting Moran effects. Ecology Letters 25(8):1854–1868. [PDF]
  • Walter, J.A., M.C.N. Castorani, T.W. Bell, L.W. Sheppard, K.C. Cavanaugh, and D.C. Reuman. 2022. Tail-dependent spatial synchrony arises from nonlinear driver-response relationships. Ecology Letters 25(5):1189–1201. [PDF]

  • Shoemaker, L.G., L.M. Hallett, L. Zhao, D.C. Reuman, S. Wang, K.L. Cottingham, R.J. Hobbs, M.C.N. Castorani, A.L. Downing, J.C. Dudney, S.B. Fey, L.A. Gherardi, N.K. Lany, C. Portales-Reyes, A.L. Rypel, L.W. Sheppard, J.A. Walter, and K.N. Suding. 2022. The long and the short of it: mechanisms of synchronous and compensatory dynamics across temporal scales. Ecology 103(4):e3650[PDF]
  • Hogan, S., E.A.K. Murphy, M.P. Volaric, M.C.N. Castorani, P. Berg, and M.A. Reidenbach. 2022. Influence of oyster reefs on infauna and sediment spatial distributions within intertidal mudflats. Marine Ecology Progress Series 686:91–106.

  • Smith, R.S., S. HoganK.N. Tedford, B. Lusk, M.A. Reidenbach, and M.C.N. Castorani. 2022. Long-term data reveals greater intertidal oyster biomass in predicted suitable habitat. Marine Ecology Progress Series 683:221–226. [PDF]

  • Lamy, T., N.I. Wisnoski, R. Andrade, M.C.N. Castorani, A. Compagnoni, N. Lany, L. Marazzi, S. Record, C.M. Swan, J.D. Tonkin, N.M. Voelker, S. Wang, P.L. Zarnetske, and E.R. Sokol. 2021. The dual nature of metacommunity variability. Oikos 130(12):2078–2092[PDF]

  • Walter, J.A., L.G. Shoemaker, N.K. Lany, M.C.N. Castorani, S.B. Fey, J.C. Dudney, L.A. Gherardi, C. Portales-Reyes, A.L. Rypel, K.L. Cottingham, K.N. Suding, D.C. Reuman, and L.M. Hallett. 2021. The spatial synchrony of species richness and its implications for ecosystem stability. Ecology 102(11):e03486[PDF]
  • Luo, M., D.C. Reuman, L.M. Hallett, L.G. Shoemaker, L. Zhao, M.C.N. Castorani, J.C. Dudney, L.A. Gherardi, A.L. Rypel, L.W. Sheppard, J.A. Walter, and S. Wang. 2021. The effects of dispersal on spatial synchrony in metapopulations differ by timescale. Oikos 130(10):1762–1772. [PDF]
  • Iwaniec, D.M., M. Gooseff, K.N. Suding, D.S. Johnson, D.C. Reed, D.P.C. Peters, B. Adams, J.E. Barrett, B.T. Bestelmeyer, M.C.N. Castorani, E.M. Cook, M.J. Davidson, P.M. Groffman, N.P. Hanan, L.F. Huenneke, P.T.J. Johnson, D.M. McKnight, R.J. Miller, G.S. Okin, D.L. Preston, A. Rassweiler, C. Ray, O.E. Sala, R.L. Schooley, T. Seastedt, M.J. Spasojevic, and E.R. Vivoni. 2021. Connectivity: insights from the U.S. Long Term Ecological Research Network. Ecosphere 12(5):e03432. [PDF]
  • Record, S., N.M. Voelker, P.L. Zarnetske, N.I. Wisnoski, J.D. Tonkin, C. Swan, L. Marazzi, N. Lany, T. Lamy, A. Compagnoni, M.C.N. Castorani, R. Andrade, and E.R. Sokol. 2021. Novel insights to be gained from applying metacommunity theory to long-term, spatially replicated biodiversity data. Frontiers in Ecology and Evolution 8:612794[PDF]
  • Castorani, M.C.N. and M.L. Baskett. 2020. Disturbance size and frequency mediate the coexistence of benthic spatial competitors. Ecology 101(1):e02904[PDF]
  • Cavanaugh, K.C., D.C. Reed, T.W. Bell, M.C.N. Castorani, and R. Beas-Luna. 2019. Spatial variability in the resistance and resilience of giant kelp in southern and Baja California to a multiyear heatwave. Frontiers in Marine Science 6:413. [PDF]
  • Castorani, M.C.N., D.C. Reed, P.T. Raimondi, F. Alberto, T.W. Bell, K.C. Cavanaugh, D.A. Siegel, and R.D. Simons. 2017. Fluctuations in population fecundity drive variation in demographic connectivity and metapopulation dynamics. Proceedings of the Royal Society B: Biological Sciences 284(1847):20162086. [PDF]
  • CastoraniM.C.N., D.C. Reed, F. Alberto, T.W. Bell, R.D. Simons, K.C. Cavanaugh, D.A. Siegel, and P.T. Raimondi. 2015. Connectivity structures local populations dynamics: a long-term empirical test in a large metapopulation system. Ecology 96(12):3141–3152. [PDF]
  • Castorani, M.C.N., K.A. Hovel, S.L. Williams, and M.L. Baskett. 2014. Disturbance facilitates the coexistence of antagonistic ecosystem engineers in California estuariesEcology 95(8):2277–2288. [PDF]