Author Archives: elhazen

Using individual based models to understand blue whale migration – published today from Steph Dodson!

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A GRIP fellow from our group, Dr. Steph Dodson has published her work with us in Ecological modeling today, titled “Disentangling the biotic and abiotic drivers of emergent migratory behavior using individual-based models.” Using published info on blue whale movement and fine scale models of krill distribution, Steph was able to test whether an IBM could recreate observed movement timing and extent. Interested in more, please read below!

Figure 2Fig. 2. (a) Model algorithm in pictorial form. The acronym ARS stands for area restricted search. (b) Behavioral states for each model. Arrows indicate possible transitions. (c) Step length and turning angle distributions for all transiting and foraging states. These distributions have been scaled from Bailey et al. (2009) to account for the 6 h time step used in the IBM. A turning angle of 0∘ corresponds to straight in all behavioral states except of the north-south model, where instead 0∘ is due south.

Dodson, B. Abrahms, S.J. Bograd, J. Fiechter, and E.L. Hazen. 2020. Disentangling the biotic and abiotic drivers of emergent migratory behavior using individual-based models. Ecological Modeling. DOI: 10.1016/j.ecolmodel.2020.109225.

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New paper by Megan Cimino modeling two krill species in the California Current.

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Megan’s recent paper uses NOAA’s RREAS cruise data to look at combined krill biomass from net-tows and differences in habitat use between T. Spinifera and E. Pacifica in the California Current. The paper highlights the issues that arise when modeling a species complex rather than individual species habitat preferences. Getting species identification will help partition net tow data in addition to fisheries acoustic measurements of krill biomass moving forward. Krill also had broad scale response to oceanic warming from El Niño events Also not surprising, predictions of high krill biomass corresponded with top predator sightings as well.

Fig. 4: Climatology (temporal mean) of predicted ln(CPUE + 1) for krill from the Full model along the central California coast (top panel) and along the U.S. West Coast (bottom panel) from 2002 to 2018 for (a, d) TSPIN, (b, e) EPAC, and (c, f) total krill. Points in (a–c) are mean observations from the mid‐water trawl sampling stations. Bathymetry line contours (contour interval of 500 m) are shown in black. The red box in (d–f) represents the region shown in (a–c).
M.A. Cimino, J.A. Santora, I. Schroeder, W. Sydeman, M.G. Jacox, E.L. Hazen, S.J. Bograd. 2020. Essential krill species habitat resolved by seasonal upwelling and ocean circulation models within the large marine ecosystem of the California Current System. Ecography. DOI: 10.1111/ecog.05204. PDF

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New paper by Mike Jacox leading the MAPP team on the importance and skill of ecosystem forecasts

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Forecasting aids in the management of marine resources and communities. New paper led by Mike Jacox reviews forecasting methods, mechanisms of predictability, and priority developments for coastal marine ecosystems.M.G. Jacox, M. Alexander, D. Barrie, S.J. Bograd, S. Brodie, A. Capotondi, K. Chen, W. Cheng, E. Di Lorenzo, C. Edwards, J. Fiechter, P. Fratantoni, R. Griffis, E.L. Hazen, A. Hermann, H. Kim, A. Kumar, Y. Kwon, M. Merrifield, A. Miller, I. Ortiz, D. Pirhalla, M. Pozo Buil, S. Ray, S. Sheridan, S. Siedlecki, A. Subramanian, P. Thompson, L. Thorne, D. Tommasi, M. Widlansky, 2020. Seasonal-to-interannual prediction of U.S. coastal marine ecosystems: Forecast methods, mechanisms of predictability, and priority developments. Progress in Oceanography. DOI: 10.1016/j.pocean.2020.102307.

Marine Top Predators as Climate and Ecosystem Sentinels published in Frontiers in Ecology and the Environment

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A recent review from our group at ERD highlights the ability for highly mobile predators to serve a role as ecosystem sentinels, by integrating the ocean processes around them, and telling us something we would not otherwise know about the oceanic ecosystems. In an ideal world, we’d have fine scale measurements of the ecosystem components and thresholds that result in change, but top predators respond in multiple scales, from changes in breeding success, movement patterns, to diet analyses we can understand more about ocean ecosystems and when changes are likely to occur. We hope this manuscript will both further the discussion of the roles of top predators in the global ocean observing system, but also as sentinels for rapid response, when ecosystem changes are likely to occur, and when adaptive management will be most needed.

E.L. Hazen, B. Abrahms, S. Brodie, G. Carroll, M. Jacox, M.S. Savoca, K.L. Scales, W.J. Sydeman, and S.J. Bograd, 2019. Marine Top Predators as Climate and Ecosystem Sentinels. Frontiers in Ecology and the Environment. DOI: 10.1002/fee.2125 PDF

Climate variability and change can result in ecosystem response via trophic pathways. Trophic linkages (gray and colored arrows) are represented in a generic pelagic food web. Solid colored lines represent a direct relationship between a sentinel via the metric measured and an ecosystem component; dashed colored lines represent the capacity of an organism to function as a leading sentinel, which can be used to predict a future ecosystem response; and dotted colored arrows represent the ecosystem link that is heralded by a leading sentinel.

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New publication in Conservation Biology by Heather Welch on validating decision support tools

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A new paper by Heather Welch titled “Decision support tools for dynamic management” in Conservation Biology highlights the role of decision support tools when integrating multiple species distribution models into a management tool. For example, the question being asked is critically important in the tool design. The algebraic formulation for EcoCast, is highly relative and scales geometrically while Marxan can have exponential relationships because of the algorithm used to ensure a certain percentage of habitat is ultimately protected. It is another good example of where there is no one size fits all approach towards tool building for multiple management goals.

Figure 3. Effect of changing management priorities for leatherback turtles and swordfish on EcoCast (top row) and Marxan (bottom row) tool outputs relative to species habitat suitability. Curves show generalized additive models fit to each weighting run.

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New publication from Dr. Steph Brodie on “Trade-offs in covariate selection for species distribution models: a methodological comparison” in Ecography

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Dr. Brodie’s new paper reveals trade-offs in species distribution modeling between accurately estimating species abundance, spatial patterns, and underlying species~environment relationships. The short answer, is there is no one best tool and choosing the right tool depends on your modeling goals. I still refer frequently to Elith et al. 2006 as a good lesson on which models are best reproducing spatial patterning, but Steph’s paper highlights that pattern is only part of the process, particularly when modeling for fisheries management.

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New publication in Global Ecology and Biogeography by Dr. Gemma Carroll titled “A review of methods for quantifying spatial predator–prey overlap”

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Papers often use the metrics most familiar to the authors without a systematic assessment of which may be the best for the given purpose. A more holistic assessment of how metrics may assess abundance, range overlap, or even temporal components of how this may change are presented by Gemma using both a case study from Alaska and simulated data. Hopefully this manuscript can serve as a guide for researchers to decide which metric may be best for their purpose when testing predator-prey overlap and how it may change over time.

G. Carroll, K.K. Holsman, S. Brodie, J.T. Thorson, E.L. Hazen, S.J. Bograd, M.A. Haltuch, S. Kotwicki, J. Samhouri, P. Spencer, E. Willis-Norton, and R.L. Selden, 2019. A review of methods for quantifying spatial predator-prey overlap. Global Ecology and Biogeography, DOI: 10.1111/geb.12984 PDF

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New publication on “Dynamic ensemble models to predict distributions and anthropogenic risk exposure for highly mobile species” by Dr. Briana Abrahms in Diversity and Distributions

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With the advent of WhaleWatch, we knew that monthly predictions and 0.25° were too coarse to inform fine scale management decisions yet that was the best we could do with the environmental data we had available. In two short years, we have now updated the model to an ensemble of multiple modeling approaches, and moved from predictions using satellite data to higher resolution ocean model output (daily and 0.10 °). Briana also used a thorough dataset of independent data to check the model’s accuracy and found very good performance, particularly during the peak of whale migration. Improving and assessing the accuracy of operational tools is a necessity, but one that we would not have been able to accomplish without support from the Benioff Ocean Initiative.

B. Abrahms, H. Welch, S. Brodie, M.G. Jacox, E.A. Becker, S.J. Bograd, L.M. Irvine, D.M. Palacios, B.R. Mate, and E.L. Hazen, 2019. Dynamic ensemble models to predict distributions and anthropogenic risk exposure for highly mobile species. Diversity and Distributions. doi.org/10.1111/ddi.12940 PDF

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New publication by Dr. Sara Maxwell on “Seasonal spatial segregation in blue sharks (Prionace glauca) by sex and size class in the Northeast Pacific Ocean”

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The question of habitat use varies significantly when separating individuals based on sex and size. Blue sharks use significantly different habitat, particularly in the fall based on their sex and size highlighting the importance of considering multiple life history stages, or at least the most vulnerable, in management.

S.M. Maxwell, K.L. Scales, S.J. Bograd, D.K. Briscoe, H. Dewar, E.L. Hazen, R.L. Lewison, H. Welch, and L.B. Crowder, 2019. Oceanographic drivers of spatial segregation in blue sharks by sex and size class. Diversity and Distributions. doi.org/10.1111/ddi.12941. PDF

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