Saipan lagoon flora: seagrass and macroalgae

(This article is the sixth of a seven week-series of articles that highlight the activities of the Coral Reef Initiative summer interns stationed at CRMO and DEQ. This week, DEQ Biology summer intern, Francisco Villagomez describes his project and work experience thus far.)

The Saipan lagoon has an abundance of organisms and all of these living things have an important ecological role. The organism called seagrass can be found all over Saipan’s lagoons: Sugar Dock, Pau Pau Beach, Kilili Beach, Dai Ichi, etc.

According to Marine Biologists Peter Houk and John Starmer, there are three kinds of seagrass that can be found in Saipan’s lagoons: Halodule uninervis which is almost comparable to the common backyard grass; Enhalus acoroides, which can grow up to 2 meters high and 2 centimeters wide; and Halophila minor, which grows in sparse leafy patches and reaches a height of 3 centimeters high. Seagrass in Saipan’s lagoon can grow in vast beds or small patches. The seagrass grows in the sandy bottom of the lagoon and takes up nutrients found in the sand. They provide food and shelter for fish and invertebrates that live in the lagoon.

Also existing in Saipan’s lagoons is macroalgae, which is often found washed up onto shore. Macroalgae that lies onshore can produce a repulsive aroma, which can often be smelled around Beach Road. Macroalgae grows in various shapes and sizes, but it should not be mistaken for seagrass. Although macroalgae can grow at a speedy rate, it does not survive as long as seagrass.

During the several past weeks as an intern at the Department of Environmental Quality, I have been taking photographs of seagrass and macroalgae located at Pau Pau Beach, Dai Ichi, and Kilili Beach. At the three sites, DEQ’s Peter Houk and I set a permanent 10 meter mark (transect, or measured line), and set down a 2 ft2 quadrat, or square, on the 1,3,5,7, and 9 meter marks, then photographed and documented the quadrat. Every week I took photos at the same sites to monitor seagrass and macroalgae. I found that on July 20, 2005, there was a sudden increase of macroalgae. The bloom of macroalgae is caused by runoff and nutrients flowing into the lagoon after a storm or heavy rain, according to Peter. Because of the heavy rainfall in the past week, there should be a greater increase of macroalgae when I return to these sites. I will continue this process until the end of my internship in August. If possible, I will be assisting Peter with analyzing the seagrass and macroalgae trends while I attend college in California.

When I was not taking photos of seagrass and macroalgae, I assisted Peter with current and habitat surveys out in the lagoon. We set current drones in the water, and followed them in a small boat. The drones drift with the current and have a flag on them so that we can follow where they go. Using GPS (Global Positioning System) we recorded their location and time to detect the direction and speed of the current. We also recorded the lagoon’s habitats, and noted whether the habitat was dominated by seagrass, live coral, or sand. These habitat surveys are conducted to map Saipan’s entire lagoon.
Working at DEQ has been a very exciting and educational experience. The Coastal Reef Initiative Summer Internship has indeed increased my interest in Marine Biology. After college, I hope to return to the CNMI as a marine biologist. (Francisco Villagomez)

Francisco Villagomez is a DEQ Biology summer intern.