american samoa - University of Hawaii at Manoa Botany Department

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dominated by willow primrose along with patches of beach hibiscus, mile-a-minute vine, andJob’s tears.Swamp ForestA swamp forest was located along edges of the standing water and marshes, e.g., around themarsh south and west of Olomoana School. Swamp forest also extended inland to near thebase of upland slopes on the south side of the Aoa wetland.Most of the swamp forest was characterized by beach hibiscus without the presence of littoralspecies such as mangrove or Pacific rosewood. Smaller banana plantations and housesreplaced the fresh-water swamp along its inland margins.Vegetation TrendsDecline of Former Mangrove ForestSignificant changes have occurred in the vegetation of the Aoa wetland since 1976. Some fouracres of mangrove were observed in 1976. In 1991, Biosystems Analysis, Inc. observed orientalmangrove, red mangrove, and beach hibiscus in the fresh-water swamp. During the November1999 survey, the remnants of the former mangrove forest represented only scattered mangrovetrees along the margins of the fresh-water swamp. Consequently, mangrove trees may benaturally dying and/or some residents may be harvesting mangrove trees for firewood or otherpurposes. In either case, domination of the fresh-water swamp by beach hibiscus and Tahitianchestnut can be expected to continue in areas that are not changed by landfills for residentialdevelopment and agricultural plantations.Changing Characteristics of the Fresh-Water MarshThe fresh-water marsh south of Olomoana School exhibited all the appearances of having beena former taro patch since it was dominated by commelina in November 1999. Following theabandonment of a taro plantation, the domination by commelina usually follows. However,this area did not appear to be a habitat where taro is typically grown, e.g., close to the ocean.Former surveys by both Whistler in 1976 and Biosystems Analysis, Inc. in 1991 did notidentify the presence of taro in this location.It is anticipated that patches of water chestnut will eventually spread over the entiredownstream area if it can out compete the typically weedy commelina. Such a trend willrequire the lack of disturbance, e.g., cultivation of taro, in the fresh-water marsh. It is unusualthat California grass, which dominated this area in 1991, was not present in November 1999. Iftrue, the California grass was replaced by commelina, due possibly to some change in habitatfactors.The disturbed marsh on the southeast side of the Aoa wetland was also quite different than thatpreviously described by Biosystems Analysis, Inc. in 1992. Biosystems Analysis, Inc. noted“.....scattered patches of beach hibiscus with an herbaceous layer of grasses”. As stated earlier,PPC observed that the marsh was dominated by willow primrose along with patches of beachhibiscus, mile-a-minute vine, and Job’s tears in November 1999. One or more of these speciesmay dominate for a long time. However, native plants such as water chestnut may invade andAmerican Samoa Wetland/Stream Restoration and Enhancement PlanFebruary 2001, Aoa Wetland, Page 4-7
ecome dominant if there is a nearby seed source since this plant is presently absent from themarsh.AQUATIC FISH AND INVERTEBRATESGeneralOn November 3, 1999, Charles Chong of the PPCfield survey team made observations of aquatic fishand invertebrates along portions of Tapua Stream andits upland tributary, Lepa Stream. His observationsare summarized in the following paragraphs.Aoa wetland contained a small estuary just upstreamof the Tapua Stream mouth. The estuary was fed bysurface runoff from Tapua Stream and Lepa Stream.Puna Stream was completely dry during theNovember 3 survey; no flows were observed at itsconfluence with Tapua Stream.Lepa StreamTapua Stream was also dry for a short distancebetween Aoa wetland the base of upland slopes onthe south side of the wetland. The stream flowthrough one set of culverts just upstream of the TapuaStream mouth was less than 0.5 cfs during the survey.FishSmall estuary upstream of Tapua Stream mouthThe estuary inside Aoa wetland and inland portion of Tapua Stream contained nearly all of thefresh-water fishes known to American Samoa. Within the estuary, Mugil and Kuhlia spp. wereabundant as were other euryhaline fishes such as Periopthalmus.The amphidromous gobioids, Stenogobius genivittatus and Eleotris spp., as well as fresh-waterspecies Poecilia reticulata and P. mexicana, were common in the estuary. Other gobies,however, were not seen anywhere in the wetland. Lower stream flow and intermittent streamflow conditions may have prevented the presence of other gobies.A few residents informed Charles Chong of the PPC survey team that anguillids were presentin the upper reaches of Tapua Stream. Captive specimens, obtained by local residents,evidenced their presence in the stream. However, Chong observed no anguillids during thefield survey.InvertebratesThe invertebrates observed in Tapua Stream and Lepa Stream included the completecompliment of fresh-water molluscs, but only a portion of the crustaceans known to AmericanSamoa. Immediately inland of the estuary, for example, two unidentified species of neritidsnails were abundant in Tapua Stream. Sisiwai and two other species were common. Alongupland Lepa Stream, only the larger smooth species of neritid snails was found.American Samoa Wetland/Stream Restoration and Enhancement PlanFebruary 2001, Aoa Wetland, Page 4-8
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Asili StreamAMERICAN SAMOAWETLAND/S
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American SamoaWetland/Stream Restor
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American Samoa Wetland/Stream Resto
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American Samoa Wetland/Stream Resto
Page 9 and 10: American Samoa Wetland/Stream Resto
Page 11 and 12: Figure 1-1Location of Potential Wet
Page 13 and 14: Onsite InvestigationsNovember 1999G
Page 15 and 16: Where appropriate, stream cross sec
Page 17 and 18: Chapter TwoTULA WETLANDLOCATIONTula
Page 19 and 20: Figure 2-2Tula WetlandExisting Cond
Page 21 and 22: Improved channelization of stormwat
Page 23 and 24: LAND USES IN THE VICINITY OF TULA W
Page 25 and 26: Figure 2-3Option 2: Detention of St
Page 27 and 28: Figure 2-4Option 3: Expansion of Ta
Page 29 and 30: Comparative Benefits and ImpactsPPC
Page 31 and 32: TABLE 2-4PRELIMINARY COST ESTIMATEP
Page 33 and 34: TABLE 2-5LONG-TERM RESOURCE MONITOR
Page 35 and 36: TABLE 2-6 (CONTINUED)FIELD MONITORI
Page 37 and 38: Chapter ThreeALAO WETLANDLOCATIONAl
Page 39 and 40: Figure 3-2Taufusi MarchExisting Con
Page 41 and 42: Figure 3-3FEMA 100-Year Flood Plain
Page 43 and 44: East Portion of the MarshThe impact
Page 45 and 46: WETLAND RESTORATION AND ENHANCEMENT
Page 47 and 48: The availability of new, blight-res
Page 49 and 50: Long-Term Monitoring and Site Maint
Page 51 and 52: TABLE 3-7FIELD MONITORING WORKSHEET
Page 53 and 54: Recommended monitoring stations or
Page 55 and 56: Figure 4-1Location MapAoa Village W
Page 57 and 58: No stream flow estimates are availa
Page 59: Fresh-Water SwampThe fresh-water sw
Page 63 and 64: Relative Abundance and Diversity of
Page 65 and 66: Option 4: Restore Mangrove Forest U
Page 67 and 68: TABLE 4-5COMPARATIVE EVALUATIONWETL
Page 69 and 70: Long-term resource management activ
Page 73 and 74: • begin at the Tapua Stream mouth
Page 75 and 76: Figure 5-1Location MapSoutheast Wet
Page 77 and 78: Tufu Stream and two stream branches
Page 79 and 80: Mr. Whistler was part of a three-pe
Page 81 and 82: InvertebratesCrustacean densities w
Page 83 and 84: FIGURE 5-3OPTION 1: RESTORE RIPARIA
Page 85 and 86: TABLE 5-4COMPARATIVE EVALUATIONWETL
Page 87 and 88: Long term monitoring of the Vatia w
Page 91 and 92: More specific monitoring of stream
Page 93 and 94: Figure 6-1Location MapVaipito Strea
Page 95 and 96: Stream FlowsHistorical Stream Flows
Page 97 and 98: California grass (Brachiaria mutica
Page 99 and 100: FIGURE 6-3FISH AND INVERTEBRATE SUR
Page 101 and 102: Most of lower Vaipito Stream segmen
Page 103 and 104: Red mangrove should be planted with
Page 105 and 106: TABLE 6-7PRELIMINARY COST ESTIMATEC
Page 107 and 108: TABLE 6-9LONG-TERM RESOURCE MONITOR
Page 109 and 110: TABLE 6-10 (Continued)FIELD MONITOR
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Vehicular and pedestrian access to
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Figure 7-1Location MapLeele-Papa-Ta
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Stream flow, in some cases, is cons
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Stormwater Discharges and Related F
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AQUATIC FISH AND INVERTEBRATESGener
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Opportunities and StrategiesOption
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Figure 7-3Option 2: Reduction of Er
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TABLE 7-8PRELIMINARY COST ESTIMATEP
Page 127 and 128:
TABLE 7-9LONG-TERM RESOURCE MONITOR
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TABLE 7-10 (Continued)FIELD MONITOR
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More specific monitoring of stream
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Figure 8-1Location MapSauino Stream
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Stream FlowsHistorical Stream Flows
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AQUATIC FISH AND INVERTEBRATESGener
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Figure 8-3Option 1: Construction of
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FIGURE 8-5OPTION 2: PLANT NATIVE RI
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Long-Term Monitoring and Site Maint
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TABLE 8-8FIELD MONITORING WORKSHEET
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TABLE 8-8 (Continued)FIELD MONITORI
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LOCATIONChapter NineLEAFU STREAMLea
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Figure 9-2Leone Pala and 300-Foot L
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However, during and following heavi
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Vegetation TrendsThe lower Leafu St
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LAND USES ADJACENT TOLOWER LEAFU ST
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Option 2: Construct Basaltic Wall,
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Figure 9-5:Stabilize East Stream Ba
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TABLE 9-7PRELIMINARY COST ESTIMATEP
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TABLE 9-8LONG-TERM RESOURCE MONITOR
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TABLE 9-9 (Continued)FIELD MONITORI
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Chapter TenASILI STREAMLOCATIONAsil
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Figure 10-2Asili Stream SegmentExis
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Stormwater Discharges and Related F
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Further downstream, the stream chan
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TABLE 10-4SUMMARY OF MACROFAUNAL OR
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American Samoa Wetlands/Streams Res
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CLEAN-UP OF LOWER ASILI STREAMLABOR
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TABLE 10-9LONG-TERM RESOURCE MONITO
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TABLE 10-10 (Continued)FIELD MONITO
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Vehicular and pedestrian access to
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Figure 11-1Location MapFusi Wetland
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WETLAND VEGETATIONNovember 1999 Sur
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The lack of stream flow entering th
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Figure 11-3Option 1: Remove Solid W
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Recommended Option and Estimated Pr
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TABLE 11-6FIELD MONITORING WORKSHEE
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Any future monitoring stations or s
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Project ManagerRepresentatives of a
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REFERENCESBiosystems Analysis, Inc.
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APPENDIX ASUMMARY OFPLANTSOBSERVED
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Species Family EnglishNameSamoanNam
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APPENDIX CSUMMARY OFAQUATIC MACROFA
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