american samoa - University of Hawaii at Manoa Botany Department

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InvertebratesIn terms of crustaceans, Macrobrachium lar and Paleomon spp. were abundant at both theupstream and downstream sites. Ptychognathus was also common at the upstream site whileMacrobrachium australe was common downstream.Two neritid snails were common upstream, but not recorded at the downstream survey site.Greater silt and sediment at the downstream site may be the reason neritid snails were notobserved downstream.Relative Abundance and Diversity of Fish and InvertebratesA site specific summary of macrofaunal organisms observed during the survey are summarizedin Table 9-4. Genera are listed in order of descending abundance within their taxonomic group.TABLE 9-4SUMMARY OF MACROFAUNAL ORGANISMSOBSERVED ALONG LEAFU STREAMStream Location Fishes Crustaceans MolluscsLowland approximately400-500 upstream of LeafuStream mouthKuhliaPoecilia (2 spp.)AnguillaEleotrisMacrobrachium(2 spp.)PaleomonNoneStation L2Source: Chong, 2000AwaousKuhliaSicyopterus (2 spp.)Stiphodon (2 spp.)Poecilia (2 spp.)AnguillaMacrobrachiumPaleomonUnidentified GraspidcrabNeritina(2 spp.)The relative abundance and diversity of fish and invertebrates along the lower and upper LeafuStream segments are summarized in Table 9-5. The characterization of relative abundance anddiversity reflects a general comparison of the abundance and diversity of fish and invertebratesobserved along lower and upper Leafu Stream segments with all 10 sites evaluated for theWetland/Stream Restoration and Enhancement Plan.Leafu Stream contained the greater bio-diversity of any of the streams surveyed for the overallstudy. The abundance and diversity of fish and crustaceans were higher compared to the other10 sites investigated for the study. The abundance of molluscs was moderate, but theirdiversity was higher.TABLE 9-5RELATIVE ABUNDANCE AND DIVERSITY OF FISH AND INVERTEBRATESLOWER LEAFU STREAMFishes Crustaceans MolluscsAbundance High High ModerateDiversity High High HighSource: Pedersen Planning Consultants, 2000American Samoa Wetlands/Streams Restoration and Enhancement PlanFebruary 2001, Leafu Stream, Page 9-8
LAND USES ADJACENT TOLOWER LEAFU STREAMThe lower Leafu Stream segment is situated withina low-density residential area of Leone Village.Within the inhabited village area, approximately 30single family homes are constructed immediatelyadjacent to the east and west banks of the stream.Although most homes are set back 100-200 feetback from the stream channel. Portions of thestream bank also used for a few, smaller bananaplantations and some decorative landscaping.The paving of the vehicular trail immediately east of Leafu Stream in 1999 may generate somebank erosion along selected stream bank reaches. During construction of the roadimprovements, no drainage inlets were installed to direct road drainage into the stream.Consequently, road drainage following normal stormwater events has begun to form naturalflow paths to Leafu Stream along the road right-of-way and some stream banks along the eastbank of the stream.RIPARIAN RESTORATION AND ENHANCEMENT OPPORTUNITIESGeneralThree opportunities were identified for the restoration and enhancement of lower Leafu Stream.One option is located upstream in the vicinity of L2 segment. The other two options representriparian enhancement project within the 300-foot stream segment immediately upstream ofLeone Pala. The scope of these restoration and enhancement opportunities, and relatedimplementation strategies, are presented in the following paragraphs. The potential benefitsand impacts derived from the implementation of the recommended strategies are subsequentlyevaluated and compared in the following paragraphs.Preliminary cost estimates are presented for the implementation of the recommended strategy.Long-term monitoring and site maintenance requirements associated with the recommendedstrategy are also identified.Opportunities and StrategiesOption 1: Restore Stream Bank in Vicinity of L2Option 1 would construct rock-filled gabions along an eroded stream bank in the vicinity ofstation L2 (Figure 9-3). The intended objective of the proposed construction would be tostabilize failing or potentially erosive stream bank areas in order to reduce downstreamsedimentation.In the vicinity of L2, gabions would be installed along selected reaches of the east and westsides of the stream. A total of approximately 100-feet of gabions would be constructed at onemore sites in the immediate vicinity of L1. In 1999, PPC estimated that such improvementswould cost approximately $20,700.American Samoa Wetlands/Streams Restoration and Enhancement PlanFebruary 2001, Leafu Stream, Page 9-9
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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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Figure 1-1Location of Potential Wet
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Onsite InvestigationsNovember 1999G
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Where appropriate, stream cross sec
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Chapter TwoTULA WETLANDLOCATIONTula
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Figure 2-2Tula WetlandExisting Cond
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Improved channelization of stormwat
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LAND USES IN THE VICINITY OF TULA W
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Figure 2-3Option 2: Detention of St
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Figure 2-4Option 3: Expansion of Ta
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Comparative Benefits and ImpactsPPC
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TABLE 2-4PRELIMINARY COST ESTIMATEP
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TABLE 2-5LONG-TERM RESOURCE MONITOR
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TABLE 2-6 (CONTINUED)FIELD MONITORI
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Chapter ThreeALAO WETLANDLOCATIONAl
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Figure 3-2Taufusi MarchExisting Con
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Figure 3-3FEMA 100-Year Flood Plain
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East Portion of the MarshThe impact
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WETLAND RESTORATION AND ENHANCEMENT
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The availability of new, blight-res
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Long-Term Monitoring and Site Maint
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TABLE 3-7FIELD MONITORING WORKSHEET
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Recommended monitoring stations or
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Figure 4-1Location MapAoa Village W
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No stream flow estimates are availa
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Fresh-Water SwampThe fresh-water sw
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ecome dominant if there is a nearby
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Relative Abundance and Diversity of
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Option 4: Restore Mangrove Forest U
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TABLE 4-5COMPARATIVE EVALUATIONWETL
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Long-term resource management activ
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• begin at the Tapua Stream mouth
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Figure 5-1Location MapSoutheast Wet
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Tufu Stream and two stream branches
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Mr. Whistler was part of a three-pe
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InvertebratesCrustacean densities w
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FIGURE 5-3OPTION 1: RESTORE RIPARIA
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TABLE 5-4COMPARATIVE EVALUATIONWETL
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Long term monitoring of the Vatia w
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More specific monitoring of stream
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Figure 6-1Location MapVaipito Strea
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Stream FlowsHistorical Stream Flows
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California grass (Brachiaria mutica
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FIGURE 6-3FISH AND INVERTEBRATE SUR
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Most of lower Vaipito Stream segmen
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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
Page 111 and 112: Vehicular and pedestrian access to
Page 113 and 114: Figure 7-1Location MapLeele-Papa-Ta
Page 115 and 116: Stream flow, in some cases, is cons
Page 117 and 118: Stormwater Discharges and Related F
Page 119 and 120: AQUATIC FISH AND INVERTEBRATESGener
Page 121 and 122: Opportunities and StrategiesOption
Page 123 and 124: Figure 7-3Option 2: Reduction of Er
Page 125 and 126: TABLE 7-8PRELIMINARY COST ESTIMATEP
Page 129 and 130: TABLE 7-10 (Continued)FIELD MONITOR
Page 131 and 132: More specific monitoring of stream
Page 133 and 134: Figure 8-1Location MapSauino Stream
Page 135 and 136: Stream FlowsHistorical Stream Flows
Page 137 and 138: AQUATIC FISH AND INVERTEBRATESGener
Page 139 and 140: Figure 8-3Option 1: Construction of
Page 141 and 142: FIGURE 8-5OPTION 2: PLANT NATIVE RI
Page 143 and 144: Long-Term Monitoring and Site Maint
Page 145 and 146: TABLE 8-8FIELD MONITORING WORKSHEET
Page 147 and 148: TABLE 8-8 (Continued)FIELD MONITORI
Page 149 and 150: LOCATIONChapter NineLEAFU STREAMLea
Page 151 and 152: Figure 9-2Leone Pala and 300-Foot L
Page 153 and 154: However, during and following heavi
Page 155: Vegetation TrendsThe lower Leafu St
Page 159 and 160: Option 2: Construct Basaltic Wall,
Page 161 and 162: Figure 9-5:Stabilize East Stream Ba
Page 163 and 164: TABLE 9-7PRELIMINARY COST ESTIMATEP
Page 167 and 168: TABLE 9-9 (Continued)FIELD MONITORI
Page 169 and 170: Chapter TenASILI STREAMLOCATIONAsil
Page 171 and 172: Figure 10-2Asili Stream SegmentExis
Page 173 and 174: Stormwater Discharges and Related F
Page 175 and 176: Further downstream, the stream chan
Page 177 and 178: TABLE 10-4SUMMARY OF MACROFAUNAL OR
Page 179 and 180: American Samoa Wetlands/Streams Res
Page 181 and 182: CLEAN-UP OF LOWER ASILI STREAMLABOR
Page 183 and 184: TABLE 10-9LONG-TERM RESOURCE MONITO
Page 185 and 186: TABLE 10-10 (Continued)FIELD MONITO
Page 187 and 188: Vehicular and pedestrian access to
Page 189 and 190: Figure 11-1Location MapFusi Wetland
Page 191 and 192: WETLAND VEGETATIONNovember 1999 Sur
Page 193 and 194: The lack of stream flow entering th
Page 195 and 196: Figure 11-3Option 1: Remove Solid W
Page 197 and 198: Recommended Option and Estimated Pr
Page 199 and 200: TABLE 11-6FIELD MONITORING WORKSHEE
Page 201 and 202: Any future monitoring stations or s
Page 203 and 204: Project ManagerRepresentatives of a
Page 205 and 206: 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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