SEA Currents: Robert C. Seamans
June 18, 2016
End of Cruise Sentiments
21° 12’ N by 157° 15’ W
Partly cloudy skies, winds BF 5 from the NE, but we are secure at anchor in lee of the Molokai Island.
We have accomplished something special here at sea onboard this ship the Robert C. Seamans. A group of strangers that worked together as a team to observe, document, and finally to understand the effects of the strongest El Niño on record on central Pacific reefs.
So what have we learned?
- Good news, the El Niño is coming to an abrupt close!
- Thankfully trade winds have returned and we had some glorious days of sailing and showing off our shellback skills in sustained Beaufort Force 6 sea conditions for the last four days. The waves and sea spray covering the deck have made us truly salty sailors as we reached to Hawaii.
- Corresponding with the winds, upwelling around the equator was noticeable in the biomass of our net tows.
- That being said, we still had the highest average sea surface temperatures on record for an SEA voyage along this cruise track during this time of year.
- The persistent warming sea conditions of this year’s El Niño have left a mark upon the reefs we visited.
- Every reef we visited showed signs of coral bleaching, but to varying degrees.
- Rangiroa, French Polynesia, our first survey, was geographically the most removed from the effects of the El Niño, and the bleaching there had only recently occurred, but signs of human disturbance were evident. But fish and invertebrate diversity were high and if temperatures moderate soon there is a good chance this beautiful reef will recover fully.
- Karoraina, Kiribati, our next survey, is only a few degrees south of the equator and has experienced the full force of this El Niño event. However, as a protected area with no human inhabitants and additional stresses on the coral reefs, we hoped for the best. The extent of bleaching was staggering. In the shallows it was clear that the bleaching was months old and short, red turf algae had already grown over the coral. But a vast majority of the reef is on a steep slope and had only recently bleached and thus will hopefully rebound quickly. Another good sign is that fish diversity, abundance, and size was even greater than Rangiroa, though invertebrate numbers were low suggesting local food web interactions were complicating the story. Being in the heart of the El Niño heat the reefs at Karoraina demonstrated the tremendous resilience reef ecosystems can have if free of other stresses.
- Kiritimati, Kiribati was another story entirely. Here, extensive human stresses of fishing and excess nutrient loads weakened the reefs and evidence of an older bleaching event was clear as a dense cover of algae had overgrown the long dead coral.
- To summarize, the students have greatly contributed to our understanding of the central Pacific Ocean, the present state of the weakening El Niño and its lingering effects upon coral reefs. Truly a set of accomplishments to which they should be proud. I thank the students and crew, one and all, that made this possible.
Though it is easy for me to focus on the scientific mission of our voyage there is much more to the story of this voyage across an ocean. Together we have sailed more than 2680 nautical miles as of writing this entry. We have created memories that will last a lifetime, and forged a community built on common purpose and shared struggle against the sea, the elements, and our own self-doubts. We have toiled together to achieve great things. This group of strangers has become shipmates and dare I say it, a family; flawed, awkward, and unique as with any family, but also full of support, encouragement and inspiration. I will miss you all.