The Catholic University of America

PROJECT OVERVIEW

Our goals.  Cetacean (whales, dolphins and porpoises) mass strandings are a longstanding mystery in the field of marine biology and continue to be recorded in coastal environments around the world. It is unclear whether these events are generally increasing in number or whether the increase is due to increased observer and research efforts, or both. In cetacean mass strandings anywhere from a few to several hundred otherwise healthy animals strand in onshore environments, often for no apparent reason.

In some instances, cetacean mass strandings have been attributed to impacts caused by naval sonar and, recently, a post-event analysis has implicated the use of multi-beam echosounders. However, these anthropogenic influences still do not explain the vast majority of cetacean mass strandings. Theories as to the cause of these cetacean mass strandings include magnetic anomalies and meteorological events (i.e. extreme tides during a new moon and coastal storms), which are thought to disorientate the cetaceans.

It has been speculated that due to the possible magnetic field sensing utilized by cetaceans, magnetic anomalies, of internal and/or external origin, could be at least partially responsible for the strandings. Internal magnetic anomalies are caused by localized structures primarily in the Earth’s crust and the external, sometimes largeamplitude, magnetic anomalies are caused by geomagnetic storms. Geomagnetic storms having widely varying spatiotemporal signatures are caused by active solar and space weather phenomena.

While the possible link between cetacean mass strandings and magnetic anomalies has been speculated previously, no definitive work exists for quantifying this idea. Our cross-disciplinary NASA-BOEM-IFAW team composed of space weather experts, marine mammal biologists and marine mammal stranding response experts has carried out the first detailed quantification of the possible link between space weather, spatiotemporal signatures of geomagnetic storms and cetacean mass strandings. Our group’s primary deliverable is the first detailed statistical analysis (published in a peer-review journal) of association between cetacean mass strandings and space weather-driven geomagnetic storms. While statistical association does not imply causative connection, the lack of association would be a clear indicator for the lack of physical connection between cetacean mass strandings and space weather.

Project team.  Our cross-disciplinary team includes leading experts on marine biology, space weather, and advanced statistical analysis techniques.

Methods. The data used in the project include: multi-agency and non-governmental organization cetacean stranding databases, geomagnetic field recordings from a global network of geophysical observatories and any other relevant space weather data such as Lagrange-1 solar wind plasma observations. While space weather and geomagnetic data sets are readily available, our work is based on a compilation of multiple cetacean mass stranding records into a single database.

We have carried out correlation analyses of the data sets by means of a case-by-case event analysis and advanced statistical analyses using techniques such as Pearson’s chisquare test to study the link between the cetacean mass stranding and space weather. The statistical analyses have taken into account both the temporal and spatial dimensions in our data sets.

Scientific impact
. The cause(s) of cetacean mass strandings is one of the key open questions in marine biology. Our work is aimed to eliminate or illuminate space weather and geomagnetic storms as possible causes of cetacean mass strandings. The conducted research directly address NASAs objective to “understand the Sun and its interactions with Earth and the solar system, including space weather.” It provides new understanding on how the near-space environment and solar activity may influence the behavior of mass stranding cetacean species. In addition, potential associations could provide the ability to predict mass stranding events and allow for effective responder preparedness.