Marine Ecology Projects

(a) = active project; (c) = completed project

PF equation

Development Movement Models and Analysis of Marine Animal Tracking Data.

1) Particle filters and smoothers for animal tracking data.(a) Collaborators: Joanna Mills-Flemming, Mike Dowd, Chris Field, Ian Jonsen and others.

Because many methods of fitting mechanistic CRW models to animal movement data are difficult and/or limiting (eg. WinBUGS or Kalman Filtering), we have developed flexible particle filter/smoother approaches for fitting these models with time-varying movement parameters. We can now implement these models to fit regular locations to irregular data and have found a particle smoother to work best. These approaches exquisitely sensitive to subtle changes in an animal's movement; changes usually missed by discrete state-switching models. The first paper from this work was published in Ecological Modelling in 2012 and demonstrated the model's ability using data collected from California sea lions.

Part smoother results


Above: Time-varying parameter and location estimates fit using a particle smoother to a California sea lion tracked in 2007 by GPS. Intensity of color indicates the movement parameter estimate at that time-step, with brighter colors nearer 1 and darker colors near 0. Note that the parameter estimates suggest a bi-phasic movement behavior for most of the track, but such biphasic movement need not be hard-coded a priori into movement models as in hidden Markov state-switching models.

ringed seals2) Modelling Southern Sea Otter movement.(a) Collaborators: Emily Golson, Tim Tinker, Jim Harvey

We've developed and implemented a new Orenstein-Uhlenbeck switching home-range model to understand how sea otters use space, how weather and dependent pups effect movement, and to assess their vulnerability to oil spills.  Our next step will be to understand the relationship between movement and space use and the well documented diet and niche specializations of individual sea otters.

tuna photo

3) Modeling Movement of Sea Lions in the Channel Islands with Tides, Currents, and Waves.(a) Collaborators: Dan Costa, Patrick Robinson, Joanna Mills-Flemming

Animals are motivated to move based on external and internal conditions, but may limit expensive movements such as migrations to periods when they are energetically least costly. We're looking at how carefully sea lions time travel between foraging areas and rookeries to ocean and tidal current patterns. These currents can enhance habitat for prey species but can also increase or decrease metabolic costs of travel depending upon time and location.

Ecology & Behaviour of Marine Mammals.

grey seal

1) Grey Seal Ecology & Behaviour.(a) Collaborators: Don Bowen, Mike Hammill, Sara Iverson, Nell den Heyer, Damian Lidgard, et al.

Work on this project began during my Ph. D. and I've continued working at Sable Island more or less continuously.   We have, and continue to collect, an exceptional long-term dataset that includes the individual life histories of hundreds of seals and have also collected hundreds of satellite telemetry tracks.  An old but extensive description of the work may be found here.  A copy of my Ph.D. thesis is available on the publications page. In the fall of 2015 a new graduate student (Janelle Badger) will begin a master's project on grey seal demography.

2) Assessing the effects of seal foraging on ground fish populations in the Gulf of Saint Lawrence and Scotian Shelf.(c) Collaborators: Valerie Harvey, Hugues Benoit, Mike Hammill, Doug Swain.

Using a variety of analytical methods, I've been involved in a variety of projects assessing the habitat use and behaviour of grey seals in areas where aggregations of demersal fishes form. This is particularly relevant given the possible interaction between commercially important fisheries and grey seals.

tuna photo

3) Ecology of ice seals.(a) Collaborators: Kathy Frost, Steve Ferguson, Sebastian Luque.

We have two projects on ice seals underway. The first is to understand the ecology of ringed seals in Hudson Bay. The second is work just getting underway on bearded seals in the Chukchi Sea. Both projects use telemetry technologies to understand movement behaviour and associations with sea ice and oceanographic features.

historic ecosystem

Marine Ecosystem Dynamics

1) Historical Ecosystem Structure of the Northwest Atlantic.(a) Collaborators: Francesco Ferretti, Loren McClenachan, Fio Micheli, Giulio De Leo, Justin Yeakel.

We're developing a project to reconstruct the ecosystem structure and dynamics of the Northwest Atlantic from 1700 to today. The approach involves the use of museum specimens and isotope analysis to estimate trophic levels and connections and reconstruct population dynamics from historical data. With this information and some newly developed and powerful modelling approaches, we can reconstruct the ecosystem dynamics and how it has changed over the pass 300 years. The goal is to reconstruct not only only the populations of major marine predators, fish populations and how their populations and ecological relationships changed as human exploitation accelerated after European settlement, but also to understand how the structure of the ecosystem destabilized, reorganized, and evolved through time. The current ecosystem is almost certainly missing major marine predators such as killer whales and walrus. However, these species were lost long ago and they have been missing from the ecosystem so long that societies living along the cost have collectively forgotten they were once key members of the Northwest Atlantic ecosystems.

This project is ambitious and complex. We expect it to take 5 to 10 years to complete, but the results will have major impacts on fisheries and conservation policies in the Northwest Atlantic.

                  Fur Seal2). Impacts of Mississippi River Nutrients on the Northern Gulf of Mexico Ocean Ecosystem. (c) Collaborators: George Jackson, Mike Dagg, Tammi Richardson

For my Master's at Texas A&M the year afterword as a research associate at the Louisiana Universities Marine Consortium, and several years afterword publishing papers, I analyzed and modelled plankton ecology and ecosystem structure in the Northern Gulf of Mexico, particularly the regions impacted by the Mississippi River effluent. This work involved a number of modelling and oceanographic surveys of the lower Mississippi River and northern Gulf of Mexico. Some time was also spent modelling the North Pacific in the Gulf of Alaska as part of GLOBEC. Much of this work is published and reprints may be found on the publications page.

historic ecosystem

3) Marine ecosystem changes in an increasingly ice-free Hudson Bay and Canadian Arctic Archipelago.(a) Collaborators: Steve Ferguson, Marianne Marcoux, Cory Matthews, Sebastian Luque, and others.

Hudson Bay and other areas of Arctic Canada are experiencing major warming and loss of sea ice. Among other effects, this change is decreasing polar bear habitat and also allowing killer whales to enter Hudson Bay. It is also changing the way seals use habitat and altering fish populations and migrations. These are profound changes across a huge Arctic ecosystem, and we're partnering with Department of Fisheries and Oceans in Canada to understand how climate change is effecting individual species as well as the whole ecosystem.

Currently we're analyzing the interactions between narwhal and killer whales. Killer whales were historically blocked from entering Hudson Bay by sea ice, but now migrate into the Bay every summer to hunt the large populations of narwhal, bowhead whales, and seals living in the shallow Arctic sea.

Conservation of Marine Predators

tuna photo

1) FMAP - TOPP Data Synthesis Project.(c) Collaborators: Barb Block, Dan Costa, Ian Jonsen, Arliss Winship, Sal Jorgensen, Elliot Hazen and others

The Tagging of Pacific Pelagics (TOPP) program of the Census of Marine Life produced an enormous amount of tracking data collected from over 30 species in the Pacific ocean. A broad synthesis of these data to highlight major patterns and important areas of the Pacific Ocean ("Hot Spots") from tracking data was a major goal. This first paper from this work was published in Nature in 2011.

historic ecosystem

2) Quantitative Movement Analysis of TOPP Bird and Mammal Dataset. (a) Collaborators: Dan Costa, Barb Block, Sara Maxwell, Scott Shaffer, Melinda Conners, et al.

The TOPP synthesis project is broad in scope, but many nested and more species specific questions remain to be investigated, many of which I began working on during my postdoc at UC Santa Cruz. While I was there I assessed methods for handling Argos error and investigated the roll of data quality on the ability to detect relevant behavioural signals and used state-space methods to relate elephant seal movement to oceanography and diving behaviour, among other projects. I continue to collaborate with students in the Costa lab group and other affiliates of the TOPP program analyzing tracking data from a variety of marine animals. A few of these students, particularly Sara Maxwell, now at Old Dominion University, are long-term collaborators.


3) Assessment of Olive Ridley Sea Turtle Habitat Use for Marine Protected Area Planning in West Africa.(c) Collaborators: Sara Maxwell (lead), Dan Costa

Sara is working to assess habitat usage of olive ridley sea turtles in order to provide advice for the construction of marine protected areas off Gabon. This includes the expansion of a current MPA and the development of a politically challenging international MPA in Western Africa. A paper on this work was published in PloS one in 2011, and based on our results the proposed international MPA is being implemented in West Africa.

Last update June 2015