Biodiversity

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

Rarotonga Snorkeling

One thing I wish I got the chance to do more of was snorkeling while we were in Rarotonga.  The lagoon tour that we did was really quite amazing.  The water was light blue and unbelievably clear; it is the kind of water I never thought I would see in person let alone snorkel in.  The creatures in the water were another amazing site to see. I feel like I saw more fish during this snorkeling session than I have in my whole twenty-three years leading up to this trip.  In addition, I saw a small eel that traveled from one rock to another, as well as Roger (a giant moray eel).  I could not believe how huge Roger looked when a crew member from the lagoon tour pulled the eel out and up from his hiding spot in the rocks!  Another thing I recall seeing was the coral garden in the lagoon.  This is where a metal grate/structure is placed on the sea floor and pieces of coral are attached to the top and grow with less space restrictions than on the coral reef itself.  It was really cool to be able to see a protective environmental measure that I have learned about in school while I was out in the lagoon; I was glad to see that the locals put forth those efforts and were educating other people and tourists about what they are doing to enhance their coral reefs.

Motu, Bommie, Patch Reef & Sandy Beach Surveys


On Thursday we left with the sun starting to peak across the water to do a full day of surveying in the lagoon surrounding the main part of Aitutaki.  We left the dock and zipped across the clear turquoise water to see the amazing coral reefs in the lagoon.  As the boat stopped we were greeted by a giant trivially (Caranx ignobilis) and crystal visibility.

We found flame tail snappers (Lutjanus fulvus), honeycomb groupers (Epinephelus merra) and Vanessa spotted a scribbled pipefish (Corythoichthys intestinalis)!   With the help of the awesome Dr.Steele we were actually able to learn what all these pretty reef fish were as scientists instead of a typical tourist simply glimpsing them on a short snorkel.

As we ventured along the white sandy-bottomed lagoon, large piles of corals called bommie’s, would appear like mountains under the sea.  Villages of fish and coral species were mystical to see.

We stopped on Barefoot island, a bit of a tourist spot to get our passports stamped as a special Cook Islands treat!

Once we were on the far motu, a small island on the outer edge, Dr. Anderson helped us identify awesome invertebrates and some cool worms we haven’t even identified yet!
This day was magical.  We learned so much and are so greatful for this amazing opportunity!

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.

Sunset wrasse 

Ciguatera has been an emerging problem within the last four or five years on Rarotonga and a few other nearby islands, such as Aitutaki. Although many people rely on reef fish populations as a food source, the sunset wrasse is untouched as it is not a public interest.  

These fish feed mainly on small invertebrates. Small snails and brittle stars are their favorite prey. Sunset wrasse are characterized as having a pink-striped head with green bands and a blue and green forebody. Their pharyngeal jaw allows them to extend their mouth widely and grind up their dinner, which sometimes could be up to half their size. They usually are present in small groups near seaward reefs and coral patches. They can be seen down to 30 meters. Incredible in many ways and my favorite fish so far!

An Intro to Cooks Natural History

Today we were fortunate to be able to hang out with the great Gerald McCormick.  Our group was too big to fit into his office, so we set-up shop on the patio of Trader Jacks.  Gerald ran through his history with the Cooks, discussed black rat (Rattus rattus) and Mynah Bird eradication projects, the downsides of balloon vine and trail-creating survey methods, deep sea mining impacts to the benthos, and the perils of a career dedicated to honest to goodness natural history and a life devoted to pure discovery and exploration of our natural world.

For anyone interested in the organisms of the Cook Islands and the places where they can be found, the best starting point is the Cook Islands Natural Diversity Database.

(We have slow upload speed so photos are hard to post here.)

  
 

    
 

    
   

The Coconut Crab

The coconut crab (Birgus latro) is the largest terrestrial arthropod and is in the same family as the terrestrial hermit crab. They live near the ocean but prefer dense forest cover. These crabs have adapted to breathing on land with their unique organ called branchiostegal lung. This lung has tissue that is similar to tissues found in gills but absorbs air instead of water.  They are omniverous and feed on fallen fruit and coconut palms. Coconut crabs have a keen sense of smell and use it to hunt food. They flick their antennae to locate smells of rotting fruit or carcasses. Coconut crabs have no known predators besides other coconut crabs and people. These crabs are hunted for their meat. In 1981, the coconut crabs was listed as a Vulnerable Species on the IUCN Redlist, but has since been listed as data deficient.

Birgus_latro

This picture was taken from Wikipedia.

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

Looking Forward

When I first found out I was selected for this trip I immediately started looking up the Cook Islands’ biodiversity.  I found bird checklists and I found that my favorite species of crab, the fiddler crab, could be found in the Cooks.  I also found that two species of albatross frequent the islands.  I cannot wait to find bird and invertebrate species I have never seen before on those islands.  I am looking forward to running CI’s sandy beach protocol on the beaches of Aitutaki and finding what kind of diversity lies on the coast. I look forward to learning about the country’s agricultural methods and land management, especially in relation to the conservation and maintenance of the islands’ ecological health.
I am also fond of experiencing new cultures and I love listening to world music when performed by natives of that culture.  I am therefore eager to experience the celebrations of the Cook Islands’ independence.

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