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Mission Blog: October 20, 2009
Benthic Habitats

By Rodney Withall, Scientist, Coral Surveys

Launching small boat.

Arriving at Midway Atoll. (Photo: NOAA)

Today marked our much anticipated arrival at Midway Atoll. For some aboard there was great excitement to set foot on land and escape the rocking seas; others were excited by the opportunity to exercise without running on the spot. A staff member of the US Fish and Wildlife service greeted us upon arrival and explained to everyone the historical and ecological importance of Midway atoll. Aside from its historical importance in World War II, Midway atoll is designated a National Wildlife Refuge and its 2.4 mi2 of land and massive surrounding lagoon are home to numerous green sea turtles, Hawaiian monks seals, and millions of seabirds.

Launching small boat.

Benthic habitat at Midway Atoll. (Photo: NOAA)

Our dive operations were slightly delayed due to docking procedures, however, we still had a full day of ecological assessments planned. While pulling into Midway, we could tell the water looked much clearer than we had previously seen on this cruise, especially having just spent 6-days diving the murky water of Maro Reef and Lisianki. Only when we launched the boats and started transiting to our first site did we realize that we could see through the water to the bottom almost 100ft below.

Launching small boat.

Stomach contents of a dead seabird. (Photo: NOAA)

With such clear water, we immediately started to notice that benthic habitats around Midway are unlike what we've seen on this cruise thus far. The Benthic team tasked with characterizing these habitats consists of Elizabeth Keenan who collects algae and coral species abundance data and Jason Helyer and I who assess coral species identity, quantity, and size class. As we rolled in to conduct our surveys throughout the day at deep and moderate sites, it immediately became apparent that sites around Midway were quite depopulate of coral compared to the diversity and abundance we just measured and counted at previous stops on this cruise. However, we did see a great abundance of coralline algae and it's likely that coralline red algae are playing a very crucial role in calcium carbonate deposition (building the reef) in the forereefs around Midway. We do expect to find greater coral cover in the backreef habitat at Midway, however, we'll have to wait until tomorrow and less swell before we can survey these shallow waters.

Launching small boat.

Divers surfacing after a deep dive at Midway. (Photo: NOAA)

The uncharacteristic warm weather we've had for the last couple days has been ideal for exploring the island. Many took advantage of the bikes made available to us on the ship to explore the island. Around every turn we're constantly reminded of how our activities can be harmful to the nesting grounds of various seabirds, but so are obvious signs of how human actions can be far reaching and impact seabird populations. To my surprise the island is littered with dead seabird carcasses, many of them albatross, and hidden inside them is indisputable evidence of how human activity negatively affects their health and life expectancy. A closer look indicates that many of these bird skeletons are filled with small fragments of plastic, plastic bottle caps, and even small bits of PVC pipe. Mistaking these small plastic fragments as potential food, seabirds will carry these forever as stomach contents until they accumulate and ultimately cause death. This image makes the message vividly clear. We, as a global population, must absolutely me mindful of how we discharge all our waste, particularly long-lived materials such as plastic that we know have detrimental effects on all marine life, including the seabirds in far remote locations like Midway Atoll.

The sun has set on another day and the ships band plays for everyone on the pier as scientists and ship's crew come together and let off a bit of steam.

 

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