National Park Service Pacific Island Network Featured Critical Issue Resource U.S. Department of the Interior Clear, Cool Streams in American Samoa Native Tuna in the Streams ?

Sampling stream fauna is an birds, and people. During Tuna (in Samoan), is also known Reproduction: Tuna spend amount of oxygen in the water, exciting part of Inventory & surveys, are caught as the giant mottled , or the their adult lives in freshwater or which makes it more difficult for Monitoring (I&M) Program with nets. Species such as marbled eel (Anguilla marmorata). estuaries, but migrate to the ocean to tuna to breathe. work in the National Park of Atyoida pilipes, Caridina reproduce. Their leaf-shaped larvae American Samoa (NPSA). The weberi, Macrobrachium Additionally, pollution such as Description: This freshwater drift into the ocean and hide among soothing sound of clear, cool lar, and Macrobrachium sewage or agricultural runoff from eel has the widest distribution plankton for about 4 months before water and the welcomed shade latimanus are found during surrounding development further of the anguillid . It can be returning to streams. Young migrate of overhanging trees makes stream surveys. depletes oxygen levels in the water. found in the tropical Indo-Pacific upstream feeding and growing for a walk in or along a stream, a Since these need to access region from East to French 8-20 years before returning to the stress reducing experience. Fishes, or i’a vai , are the ocean as part of their life cycle, Polynesia as well as rivers in Japan sea to reproduce. But a more compelling reason important food for large they may need to travel through and Mozambique. Adults are long for studying these animals is that The field crew works together to birds. People catch them for food more open areas as part of their and slender and have brown to they are important to the riparian catch stream shrimp. and sport as well. Fish are not journey to or from the ocean. If the black marbling on their backs (stream) ecosystem. collected during surveys but they are amount of dissolved oxygen in the over a greyish yellow base, and a identified and recorded when seen. water is low due to lack of shade white belly. They can reach lengths Snails, or sisi vai, keep algae growth or elevated pollution, the animals' of 2 meters weighing a robust 20 under control. They feed by scraping Stream animals are important progress may be deterred. kilograms, though they typically the algal film from rocks and other indicators of the quality of the water. measure around 80 cm in American surfaces using a ribbon of teeth. Healthy streams naturally have a The Inventory & Monitoring Samoa streams. This species is The size, shape, texture, and color of balanced mix of native animals. Program monitors extremely long-lived with age their shells are important features for During stream animal surveys, the populations annually, and water estimates up to 40 years. identification. Snail eggs are attached water quality itself is also analyzed quality parameters quarterly. to submerged rocks or other hard to ensure that streams remain The field crew carefully removes an eel Monitoring includes vital surfaces in streams, or even attached healthy. Habitat and Diet: Don't be from a shrimp net during a survey. measurements such as temperature to the shells of other snails. Although Shrimp are counted, identified, alarmed if you see an eel slithering and dissolved oxygen. and released back to the stream. only a millimeter or two in size, the The I&M Program currently your way. Tuna are capable of Threats: Eels, like all freshwater eggs are easily seen as clusters of monitors three streams on Tutuila limited overland travel, especially fish, are cold-blooded and breathe Giant Mottled Eels in Island. Monitoring Fagatuitui during rainy periods which keep white ovals or sesame-seed shapes using gills. Since they cannot PACN National Parks: against the dark rocks. Species such Stream requires a long hike which their skin moist out of water. regulate body temperature, their The giant mottled eel is common in as Clithon corona, Septaria suffreni, is twice as hard on the way back. In They can be found in all areas of bodies are the same temperature streams on Tutuila and Ta‘u Islands Septaria sanguisuga, Neritina canalis, contrast, Leafu and Amalau Streams the stream from the mouth to the as the water. Temperature affects in the National Park of American and Melaniodes tuberculata are only require a simple stroll from headwaters. They are primarily the eels' metabolism and the Samoa.This species is also found found throughout Samoan streams. nearby villages. In the past, the nocturnal and eat a wide range of amount of oxygen in the stream. In in Asan Stream on the island of Snails are hand collected and I&M Program also sampled Laufuti prey including , fish, and . undeveloped areas with abundant Guam in War in the Pacific National released during the annual surveys. stream on Ta‘u Island, which is less tree cover, the water temperature Historical Park. influenced by humans than the remains relatively constant;

Shrimp, ula vai, filter organic debris The field crew meticulously Tutuila Island streams. therefore, the animal’s metabolism —A. Farahi, NPS from flowing water and hunt insect identifies a shrimp. and amount of oxygen in the water Biological Technician larvae hiding among small stones. NPSA’s freshwater animals are will also be relatively constant. They are the most abundant mid- fascinating to study. Sharing this However, in more developed areas sized animals in Samoan streams. experience with others makes it where land has been cleared for Most are only a few centimeters even more enjoyable. housing or agriculture, the water Caught on Video: We long and are well camouflaged. is more exposed to the sun and captured this tuna on video last Others, belonging to the genus temperature fluctuations during the time the stream crew was working Macrobrachium, or "large arm”, are —V. Vaivai, NPS day. The warmer water increases in American Samoa. www.youtube. easier to spot because of their larger Biological Technician the eels' metabolism making them com/watch?v=znXY0WEvvu0 Occasionally, a giant mottled eel will size and bold behavior. Shrimp are A hermit decides to take hungrier. The relative warmth move about on land for a short time in an important food source for fishes, some notes of its own. simultaneously decreases the search of food.

January 2013 Pacific Island Network