Oceanography

By uncovering pieces to the puzzle of the mysterious mass death of 337 whales in 2015, Expedition HF27 will be conducting CTD cast transects throughout Golfo de Penas, coupled with nutrient and gas measurements, bringing some of the first data on the oceanographic conditions of Golfo de Penas to the world.

Fjords come in a wide variety of forms, but are usually long, thin bodies of water.  They often have deep, glacially-scoured basins with one or more narrow or shallow constrictions.  Surface water is relatively fresh, from inflowing rivers, and tends to flow seaward, flushing out any floating objects.  Heavier sea water flows in at depth beneath this surface layer. This means that the nature of the water within a fjord is highly dependent on the amount of river water that enters it and the ability of water to pass the constrictions.   To understand better these aspects we will be measuring water properties on transects along these fjords and into coastal waters.

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Map of oceanographic stations. We will conduct 3 transects in Estero Slight, Seno Newman and Seno Escondido. These transect regions are linked by stations in the center of Golfo de Penas and Golfo Tres Montes, creating a gradient between Fjord and Oceanic systems. (carta: SHOA Chile)

Perhaps the most perplexing aspect of the Sei whale mass mortality event is that many of the stranded whales were found in fjords and inlets, often at their very heads, furthest from the sea.  Not only do these sites not fit with the known habitats of these oceanic species, but it seems highly unlikely that they could have drifted there from more open waters.    Conducting oceanographic surveys will help us answer questions about the fate of nutrients, whether these fjords could support algal blooms, and whether the whales entered them in pursuit of food, or were likely feeding in nearby coastal waters.