Distribution

Remotely Operated Vehicle Reef Surveys

Today the AARR team set out to conduct the first reef surveys using ROVs on Aitutaki. The beginning of the day started out a little rough with one of the ROVs flooding which forced the team to return to base to grab the back up unit. Once back underway, a total of five surveys were successfully completed, four of which were within the lagoon and one outside along the edge. Average transect length was 35 m with the duration of the surveys lasting approximately 2 minutes. Depth, water temperature, and heading of transects were recorded with an onboard inertial measurement unit (IMU). Average depth of the surveys was 3.64 m, average temperature was 23.9 Celsius, and average heading was to the North (with the current). Surveys were conducted on all sides of the island (north, south, east, and west) to determine if there is a difference in fish abundance and species richness.

 

A preliminary analysis of the videos showed the reef area outside of the lagoon had the highest fish abundance and potentially the highest species richness. Also, the surveys on the east side of the island appeared to have the lowest abundance and richness overall. However, a more thorough examination of the videos followed by a statistical analysis is required to confirm these assertions.

 

The unit that flooded was flushed with freshwater to remove salt from the electronics and dried the rest of the day. This evening we put it back together to see if it would turn on, which luckily it did! The unit was outfitted with the bio-fluorescent sensory package once again will be launched to look for fluorescing coral later tonight.East side Lagoon Forward

Clam Hatchery 

A couple days ago we visited the Marine Research Center and looked at the clam hatchery. Charlie Waters, a specialist regarding clams, gave us a thorough explanation about the reasons for low spawning success and the purpose of his research. Charlie explained that low reproduction was due to the distance between individuals. Each species of clam are too far away from each other to spawn, those species include; genera tridacnidae maxima, tridacnidae gigas, tridacnidae derasa and the genera hippopus.  

In the 20th century, many areas in the Cook Islands relied on clams as a food source, and therefore many clams were removed from the population overtime causing a decrease in the abundance of clams. Clams are significant to the reefs as they are coral reef filter feeders and food for the octopus as well as other marine life. When they are spread to thin, the cannot reproduce. This could easily offset the balance of marine environments.

With the current ciguatera research in place my assumption is that with the lack of clams, increase in tourism, the previous banana exportation, and chemical runoff the reefs and lagoons are less viable to fighting off the neurotoxin. It may also be that the potentially ciguatoxic coral is spread when large storms come through, causing unsettled ocean water and debris.

Sea Level Rise

With global warming on the rise, small island nations are already noticing the negative effects. The Cook Islands are said to be the subject of drastic sea level rise within the next 25-40 years. With that, the residents of these islands must face the harsh consequences that affect the things they are most reliable on: marine resources, agriculture, water resources, and even the stability of a home. Coral reefs, which hold many economic and cultural values, begin to fail with ocean levels rising. In addition, salt intrusion starts to diminish the productiveness of their crops and abundance of freshwater on the islands. Also, the rising sea levels (along with the severity and increased occurrence of storms due to global warming) take a toll on the homes of residents. Each of these features is a key part to the survival of the people on the Cook Islands. If sea levels rise to a point where these islands become inhabitable, then their traditions, culture, and possibly language become in jeopardy of becoming nonexistent. We need to put more effort into figuring out a way to combat these challenges that sea level rise bring before we begin to lose the rich culture of the people who resides on these islands.

Sources:

http://www.pacificclimatechange.net/index.php/country-profiles/cook-islands

http://coralreefsystems.org/sites/coralreefsystems.org/files/u8/jar_reef5_smith_450.jpg