We are excited to have returned safely from a very successful expedition to Golfo de Penas. The final count is in, and Expedition HF27 has reeled in a grand total of 1,051 samples!
After arriving to Puerto Montt, we presented all samples to Chilean authorities for inventory and revision, and now we are able to distribute samples to their respective specialists and laboratories for analysis. We are very excited to see results from analyses for stable isotopes, trace elements, Paralytic Shellfish Poisoning (PSP), phytoplankton abundance and species richness, virology, oceanographic nutrients and gasses, and DNA. The resulting information will not only provide insights into the mass mortality event of the Sei whales, but also their general life histories and, most importantly, the marine and terrestrial environment of Golfo de Penas overall.
Here is the breakdown of sample totals:
- Nutrients: 182
- Gasses 370
- Plankton 90
CTD CASTS 45
- Munida packets: 3
- Mussels packets:5
- Stable Isotopes (plants, earth): 137
- PSP tests: 25
- Necropsy: 138
- DNA : 35
- Baleen: 21
GRAND TOTAL: 1051
While still keeping in mind the unclear seasonality, residence time and patchiness of Harmful Algae Bloom (marea roja) events in Golfo de Penas, it must be noted that we received 19 negative results of Paralytic Shellfish Poisoning (PSP) tests from all around the entire Golfo. 11 of these negative results come from Phytoplankton samples, 6 come from mussels and 2 come from Munida samples. One of these negative resulting Munida samples came from the duodenum (an organ just below the stomach along the digestive tract) of a necropsied whale.
We did receive some ambiguously positive results from our field PSP tests. These three samples come from Phytoplankton near the head of Seno Newman, where the water was a bright iodine-like color, and plankton tows brought up a large quantity of filamentous green algae and thousands of very small amphipod and shrimp-like creatures (sizes where <5mm). However, repeat sampling three days later resulted in a negative test. Laboratory qualitative, quantitative and chemical analysis will provide more detailed insights in the future. For more information, please check back for a more detailed report under Project, Phytoplankton on this blog.
These initial findings, combined with observations of at least 2 large pods of orcas attacking Sei whales (see Keri’s post and Greg’s post), and the appearance of many newly dead Sei whales along beaches in areas where orcas are present and PSP is not, leads us to begin to shift our research focus as we look towards our return to these sites in May. Some immediate questions that arise are (1) Could it be that orcas are responsible for all, or the majority, of the 337 whales’ deaths reported from last year ?(2) How many new whales will we find in May ? (3) What is the scope of the orca-baleen whale interaction in Golfo de Penas and Chilean Patagonia? (4) Is there connectivity between other regions? (5) Did red tide really play a role in this event? How much?
These are just a few questions that we are doing our best to prepare for over the next two months. And in the meantime, we will be working on compiling our findings from this expedition, especially the observed orca and Sei whale behavior, into a succinct report to be widely communicated.