A Study of the Invertebrates in the Algae of the Ala Wai Estuary
By: Team Snow Panther (Tom Hartwell, Kelli Torigoe, and Erin Nakatsuka)
January 14, 2011
In this investigation of the invertebrates in the algae of the Ala Wai, we intended to retrieve algae from different zones of the estuary and identify and count the organisms present. We harvested the algae using long rakes and then rinsed through it using strainers to capture all the creatures. Then using microscopes and cameras, we identified, photographed, and counted them. We were only able to browse through the algae on three separate occasions, but we were still able to find amphipods and isopods in abundance. Other organisms we found include flatworms, ophiocomas, annelids, and ostracods. The lack of algae could have been caused by the heavy rains that occurred before our laboratory days.

I. Introduction and Research
The Ala Wai Canal was built in the 1920’s to help drain the swampy areas now known as Waikiki. The
Manoa, Palolo, and Makiki streams all meet in the estuary and mix with the salt waters of the Pacific Ocean. This smaller body of water responds to the slightest environmental changes which allows for extensive experimentations and examination (Glenn and McMurty, 1995). Each section of the canal varies in many factors like salinity, chemical content, and amount of oxygen. These factors create different environments and habitats for the plants, animals, bacteria, and elements present within the estuary.
In our study of the Ala Wai Estuary, we identified and counted the invertebrates inhabiting the algae in the depths of the Ala Wai. From previous research by our fellow classmates, we were given an idea of what kind of organisms we should be able to find and where they would be found. Some of those organisms include amphipods, copepods, and isopods.
Amphipods are a part of the crustacea order, but they don’t have a carapace, a hard covering over their body, like most crustaceans (Fasulo, 2009). Their bodies are either long and skinny or short and compact (Museum
Victoria, 2000). They can be identified by their seven pairs of legs and two antennae. Also amphipods are usually green, brown, or black and often turn red when they are dead. There are over 90 species that live in both fresh and salt water environments. Most amphipods live on the beach under rocks or plants. Adult amphipods range from 5 to
20 mm (Fasulo, 2009). Depending on the environment of the amphipods, they feed on seaweed, bacteria, or dead animals and plants (Museum Victoria, 2000). Once a female amphipod’s eggs are fertilized by a male amphipod, the eggs are placed in a pouch on the underside of her body where it develops for one to three weeks. Most amphipods look like smaller adult versions when they are released from the pouch (Fasulo, 2009). Alga provides a perfect environment for the amphipods because they must be in a moist area at all times.
Isopods are the most diverse in form and are inhabitants of almost all environments. The Isopoda include approximately 10,000 different species, in the described suborders (Brusca, 1997). They range from 0.5 to 500 mm, and fossil research suggests that they have been present for at least 300 million years (Brusca, 1997). All marine shorelines in the world are inhabited by the three common species, Idoteidae (Valvifera), Sphaeromatidae
(Flabellifera), and Cirolanidae (Flabellifera), and in soft-bottom offshore environments, species of the suborders
Asellota, Anthuridea, and Gnathiidea are very common (Brusca, 1997). Along with their diversity in habitats, isopods, have many different eating habits, too. Some are herbivores while others are parasites, and even carnivores.

The herbivores can influence the surrounding vegetation by helping to spread the roots that they consume (Brusca,
1997). Similar to amphipods, isopods carry their eggs in a pouch until their offspring are ready to hatch.
We also found Ophiocoma echinata which is usually found in coral reefs or under rocks in the ocean
(Degnan, 2003). Since Ophiocoma echinata is considered to be a brittle star, they have a unique ability to regenerate lost arms. Another interesting invertebrate we came across was flatworms. Flatworms can be found in various bodies of water and can range from 10-40 mm (Canterbury, 2010). Flatworms consume smaller animals and can reproduce asexually and sexually because they have both male and female parts. In addition to the flatworms, we found similar worms called annelids. Annelids that are most well known are earthworms, but there are also many species that live in water (Ramel, 2010). Differently from flatworms, they are long and skinny instead of flat.
II. Materials and Method
1.
Gather algae in buckets using long rakes in all zones of the estuary. a.
We were limited to gathering in zone 5 because there was no alga in the other zones.
2.
Rinse through the alga and tear it into smaller pieces, making sure to collect all the water used to rinse the alga.
3.
Remove as much algae from the buckets as possible.
4.
Dump the excess water into another bucket and collect the organisms using a strainer.
5.
Identify and count the organisms with the help of a microscope. Be sure to record the approximate size, take pictures, and note specific characteristics.
6.
Record all findings; note the environmental factors of the date and time of collection, and what area the alga is from.
Date
Site Organism
Sampling
Method
Magnif ication
Average
Size
(mm)
Quantity Color Other Image

10/02/20
10 10:00
5
Pachygraps us fakaravensi s
Algae
Collecetion n/a 4.23 (cm) 4
Brow n
3 males,
1 female
10/02/20
10 10:00
5 Ophiocoma
Algae
Collection n/a 1.3 2 black
10/02/20
10 10:00
5 Amphipod
Algae
Collection n/a 1.20 104 black
10/30/20
10 11:36
Site 5 Amphipod other 10 x 4 1.20 3 black
Found in algae
10/30/20
10 11:30
Site 5 Isopod other 10 x 4 1.00 74 brow n
Found in algae
10/30/20
10 11:30
Site 5 Ophiocoma other n/a 1.00 2
10/30/20
10 11:30
Site 5 Flatworm other n/a 1.2mm 1 black
Found in algae clear
Found in algae

11/27/2
010
10:57
Site
5
Annelids algae collection
10 x 4 6
Found in algae
11/27/2
010
10:56
Site
5
Isopods algae collection
10 x 4 1.00 5 brow n
Found in algae
11/27/2
010
10:55
Site
5
Amphipods algae collection
10 x 4 1.00 13 black
Found in algae
11/27/2
010
11:02
Site
5
Ostracod algae collection
10 x 4 1.00 1
Found in algae
IV. Discussion
For our experiment, we needed to gather algae to determine the organisms that inhabit it. We either used algae gathered by other groups or raked the bottom of the Ala Wai Estuary to gather it ourselves. Once the algae was harvested we strained it using various devices to separate the organisms from the algae. When separated, it was fairly easy to identify the various organisms. We used data previously collected to identify the different organisms.
When there was an organism that was unknown, it was simply looked up online or in one of the many books available.
All of the algae were located in Zone 5. After the first algae collection, there were heavy rains. From that point on, it was difficult to locate any algae whatsoever. On occasion, small samples were pulled from Zone 5. It is likely that the rains washed all the algae downstream and most of it was washed out towards the ocean. Because of

the short time span between rainfalls the algae did not have significant time to reestablish itself in the area. The few pieces that were found, were probably caught on a branch or rock while being swept downstream.
The majority of organisms found in the algae were smaller creatures around 1 mm in size. Of these the majority were amphipods and isopods. However, while many of the amphipods were found alive, only one or two of the hundred or so isopods were alive. It also appeared as if they had been dead for some time. It is possible that while amphipods make the algae their home throughout the life cycle, the isopods only live their when they are near death. Either that or there was something that killed most of the isopods but did not affect the other organisms.
These small organisms live in the algae probably for protection from predators. Some may also use the algae as a food source. Without actually observing the algae-organism relationship in the wild, it is difficult to determine if it is a parasitic or symbiotic relationship. It is safe to say that the organisms did not just happen to be in the algae when we gathered it because no matter the amount of algae collected or what day, these organisms were always present.
It is also possible that other larger organisms live in the algae. When the first algae was gathered, four large crabs ranging from 2.7-5.2 cm were found. Some young shrimp were also found as well as crabs around 5 mm.
These creatures probably used the algae for protection from predators and food also. However, because only one algae sample was collected with the said organisms, it is impossible to know if that was the only case in which these creatures lived in the algae. If more samples were discovered that had these organisms, a conclusion would be easier to reach.
There were some possible errors that could have possible led to incomplete data. Because the water is unsafe to dive in, it was impossible for us to actually dive into the Ala Wai to collect algae. This would also have been difficult because of the low visibility within the water. Using the rakes only allowed us to cover a small area on the estuary floor. Because we could not see what the rakes were gathering, we were unable to tell if we had algae on the rake so deciding when to pull it up was a guessing game. It is likely that algae fell off the rake when it was being pulled up. Also, there were either very little algae in the Ala Wai Estuary to begin with or the rains washed all of it out to sea. Data collected over the summer, suggest that there was an abundance of algae so it is likely the fault of the rain. If we had better collection methods, and better luck, we would have been able to collect a more complete set of data and reach stronger conclusions.

V. Conclusion

This lab could be extended by observing the algae in zones 1 to 4 of the Ala Wai in closer depth. Although the original objective was to collect the different algae in all sections of the Ala Wai and compare the data, algae was only obtainable in zone 5. The study can be broadened by examining the different sections of the
Ala Wai and its environment to determine which algae survive where, and why, to a more specific extent.
It can also be extended by researching if weather was the sole reason why algae were found in only zone 5.

The Ala Wai is a prime example of an estuary that contains many different environments within its partly enclosed body of water. The Ala Wai is a habitat to many different species, and the algae and other organisms that are found in this little world are vital to life’s variation. Exploring the algae will enrich knowledge and familiarity with diverse species, and whether they are parasitic and harmful, contribute to vegetation, or are vital to the existence of human beings. Exploring the algae will broaden our familiarity with these species in determining how they affect life and their surrounding environments.

All of the algae were located in Zone 5. Small organisms live in the algae probably for protection from predators. Some may also use the algae as a food source. Without observing the algae-organism relationship in the wild, it is difficult to determine if it is a parasitic or symbiotic relationship. The majority of organisms found in the algae were smaller creatures around 1 mm in size. The majority found were amphipods and isopods. However, while many of the amphipods were found alive, most of the isopods were found dead. It is possible that while amphipods make the algae their home throughout their life cycle, the isopods only live there when they are near death, or that there was something that killed most of the isopods but did not affect the other organisms. Another conclusion could be that the algae in zone 5 was not the isopod’s natural habitat and they were forced to migrate because of the rains.

It is also possible that other larger organisms live in the algae too. Four large crabs ranging from 2.7-5.2 cm were found. Some young shrimp and crabs around 5 mm were found as well. These creatures probably used the algae for protection from predators and food. However, because only one algae sample was collected with these organisms, it is impossible to determine if that was merely a coincidence or a specific circumstance. If more samples were discovered that had these organisms, a conclusion would be easier to reach.

VI. Works Cited
Brusca, Richard. (1997). Isopoda , Retrieved Nov. 23, 2010, from The Tree of Life Web Project
Web Site: http://tolweb.org/tree?group=Isopoda
Canterbury Environmental Education Centre. (2010). Flatworms , Retrieved Nov. 23, 2010, from
Nature Grid Web Site: http://www.naturegrid.org.uk/biodiversity/invert/ flatworm.html#top
Degnan, Katherine. (2003). Blunt-Spined Brittle Star Opiocoma echinata , Retrieved Nov. 23,
2010, from Marine Invertebrates of Bermuda Web Site: http://www.thecephalopodpage.org/MarineInvertebrateZoology/Ophiocomaechi ata.html
Glenn, Craig and Gary McMurty. (1995). Scientific Studies and History of the Ala Wai Canal, an
Artificial Tropical Estuary in Honolulu , Retrieved Nov. 23, 2010, from ScholarSpace at
University of Hawaii Web site: http://scholarspace.manoa.hawaii.edu/handle/10125/2327
Fasulo, Thomas R. (2009). Terrestrial Amphipods or "Lawn Shrimp," (Crustacea: Amphipoda:
Talitridae , Retrieved Nov. 23, 2010, from University of Florida IFAS Extension Web site: http://edis.ifas.ufl.edu/in377
Museum Victoria. (2000). The Biology of Amphipods , Retrieved Nov. 23, 2010, from Museum
Victoria Web site: http://museumvictoria.com.au/crust/amphbiol.html
Ramel, Gordon. (2010). The Phylum Annelida , Retrieved Nov. 23, 2010, from Earth Life Web
Site: http://www.earthlife.net/inverts/annelida.html