[MARMAM] New publication on crabeater seal habitat use in the Weddell Sea

Mia Wege mia.wege at gmail.com
Thu Aug 13 02:03:56 PDT 2020

 Dear MARMAMMers,

My colleagues and I are pleased to announce our latest publication in
Diversity and Distributions:

Wege, M., Salas, L., LaRue, M. (2020) Citizen science and habitat modelling
facilitates conservation planning for crabeater seals in the Weddell Sea.
Diversity and Distributions. https://doi.org/10.1111/ddi.13120

Creating a network of marine protected areas in the Southern Ocean requires
extensive knowledge on species’ abundances, distributions and population
trends especially in the Weddell Sea where year‐round pack ice makes most
of the Weddell Sea inaccessible. We combine satellite images and citizen
science to model habitat suitability for crabeater seals (*Lobodon
carcinophaga *) throughout the Weddell Sea.

Weddell Sea, Antarctica.

High‐resolution satellite images covering 18,219 km2 of the Weddell Sea
during crabeater seal breeding season (October—November) were hosted on the
crowd‐sourcing platform Tomnod (DigitalGlobe). Citizen scientists marked
“maps” where seals were present/absent and these votes were compared with
the votes of an experienced observer. Correction factors were used to
correct votes to either a continuous probability of seal presence, or a
binary seal presence/absence value. We modelled probability of seal
presence using ensemble models of Random Forests (RF), Boosted Regression
Trees (BRT) and Support Vector Machines (SVM), and used fitted Maxent
models to model seal presence/absence data.

Model predictive power was low (RF: *R *2 = 0.076 ± 0.002: BRT: *R *2
= 0.086 ± 0.0008;
SVM: *R *2 = 0.082 ± 0.003) to average (Maxent: AUC = 0.71 ± 0.004).
Distance to the ice edge and bathymetry were the most important variables
that influenced crabeater seal distribution.
Main conclusions

Crabeater seals were more likely to be present over abyssal water, which
coincides with typical adult Antarctic krill habitat — crabeater seal
preferred prey. Where ice concentrations were more variable, that is more
accessible, crabeater seals were also more likely to occur. Results agreed
with the known ecology of crabeaters seals and the abundance, distribution
and ecology of Antarctic krill. We were able to survey the largest area
ever surveyed in the Weddell Sea and provide a model to assist furthering
policy around the proposed protected area.

All the best,
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