Mignucci-Giannoni, A.A.

The red lionfish (Pterois volitans) is an invasive predatory marine fish that has rapidly expanded its pres- ence in the Western Hemisphere. We collected 214 invasive red lionfish samples from nine countries and territories, including seven unpublished locations. To more compre- hensively evaluate connectivity, we compiled our d-loop sequence data with 846 published sequences, resulting in 1,060 samples from 14 locations. We found low nucleo- tide diversity (π = 0.003) and moderate haplotype diversity (h = 0.59). Using haplotype population pairwise ΦST tests, we analyzed possible phylogeographic breaks that were pre- viously proposed based on other reef organisms. We found support for the Bahamas/Turks/Caicos versus Caribbean break (ΦST = 0.12) but not for the Northwestern Carib- bean, Eastern Caribbean, or US East Coast versus Bahamas breaks. The Northern Region had higher variation and more haplotypes, supporting introductions of at least five haplo- types to the region. Our wide-ranging samples showed that a lower-frequency haplotype in the Northern Region domi- nated the Southern Region and suggested multiple introduc- tions, possibly to the south. We tested multiple scenarios of phylogeographic structure with analyses of molecular vari- ance and found support for a Northern and Southern Region split at the Bahamas/Turks/Caicos versus Caribbean break (percentage of variation among regions = 8.49 %). We found that Puerto Rico clustered with the Southern Region more strongly than with the Northern Region, as opposed to previous reports. We also found the rare haplotype H03 for the first time in the southern Caribbean (Panama), indicat- ing that either secondary releases occurred or that the low- frequency haplotypes have had time to disperse to extreme southern Caribbean locations. 

Abstract:

1. Killer whales Orcinus orca are found in all oceans of the world, but most of our knowledge on the species comes from studies conducted at higher latitudes. Studies on killer whales in the Caribbean have been scarce.

2. We compiled 176 records of killer whales from the Caribbean, including 95 previously unreported records and 81 records recovered from the literature, consisting of 27 capture or kill records, 4 stranding records and 145 sighting records.

3. Our results indicate that killer whales are widespread in the Caribbean Sea and can be found year-round in the region. Mean group size was 3.7 animals. A diversity of prey items was recorded, including sea turtles and marine mammals and possibly fish. We cannot exclude ecotype or morphotype-specific dietary specialization in the Caribbean population. A preliminary morphological analysis of 10 characters in 52 individuals from 21 different groups suggests that Caribbean killer whales do not represent any of the four Antarctic and subantarctic types, type 1 from the northwest Atlantic, or ‘resident’ and ‘transient’ killer whales from the northwest Pacific. Some Caribbean killer whales share a combination of characters typical of type 2 in the North Atlantic, whereas others share those typical of ‘offshore’ killer whales in the northwest Pacific. The significance of this is unclear. Comparison of Caribbean killer whales to previously described morphotypes and ecotypes is hampered by the lack of detailed, quantitative data on variation within other types, as well as by the lack of comparisons of genetic diversity.

4. Our study adds to the growing knowledge of the diversity of killer whales worldwide but underscores that additional research is warranted in the tropics.