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Endoparasitic insights of free-living fin (Balaenoptera physalus), humpback (Megaptera novaeangliae) and North Atlantic right whales (Eubalaena glacialis) from Eastern Canadian waters

100%

Kleinertz S. , Silva L. M. R. , Kopper S. , Hermosilla C. , Ramp C.

2021

tom 66

nr 2

Africanacetus from the sub-Antarctic region: The southernmost record of fossil beaked whales

80%

Gol'din P. E. , Vishnyakova K. A.

nr 3

We report two partial skulls of fossil beaked whales (Odontoceti, Ziphiidae) of uncertain age trawled from the sea floor of the sub−Antarctic Indian Ocean (58 to 60S), representing the southernmost record of the family. The skulls possess diag− nostic features of the genus Africanacetus, several specimens of which have been recovered from the sea floor off South Africa, but differ from the type and only known species Africanacetus ceratopsis in their larger size. This difference may either reflect intraspecific variation or indicate the existence of a hitherto unrecognised species. The two specimens are characterised by unusually developed mesorostral ossifications, combined with maxillary crests occurring in the facial re− gion. Both of the latter are found in a range of extant and extinct ziphiids, and known to be sexually dimorphic in extant beaked whales. These structures may be the result of hypermorphosis driven by sexual selection, and could be involved in male−specific behaviour.

Greenland whales and walruses in the Svalbard food web before and after exploitation

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Weslawski J. M. , Hacquebord L. , Stempniewicz L. , Malinga M.

nr 1

Between 1600 and 1900 two numerous and ecologically important large marine mammals were extirpated in the Svalbard archipelago. These were the pelagic-feeding Greenland whale (Balaena mysticetus) and the benthic-feeding walrus (Odobaenus rosmarus rosmarus), the initial stocks of which prior to exploitation are estimated to have numbered approximately 46 000 and 25 000 animals respectively. Their annual food consumption at that time is estimated to have been some 4 million tons of plankton and 0.4 million tons of benthic organisms. Assuming that the primary and secondary production of the shelf/coastal ecosystem in the 16th century (before the peak of the Little Ice Age) was similar to that of the present day, the authors have concluded that a major shift in the food web must have occurred after the Greenland whales and walruses were eliminated. Planktonivorous seabirds and polar cod (Boreogadus saida) very probably took advantage of the extirpation of the Greenland whales, while eiders (Somateria mollissima) and bearded seals (Erignathus barbatus) benefited from the walrus's extinction. In turn, the increased amount of pelagic fish provided food for piscivorous alcids and gulls, and may have given rise to the huge present-day seabird colonies on Svalbard.

Dolphin-Inspired Target Detection for Sonar and Radar

50%

Leighton T. , White P.

nr 3