The Ecology of Tidal Freshwater Marshes of the - USGS National ...

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eaches of coastal rivers such as theNetlse and Pam1 ico. As a result, almostall North Carolina coastal river systemshave sections which are both tidal andfreshwater. However, the tidal range isslight; and tides are irregular, andgreatly affected by the wind. Therefore,in North Carolina the types of plant communities typical of most east coast tidalfreshwater sites (see Chapter 2) arerestricted in size and are replaced bytidal swamps. The one major exception inNorth Carol ina is the Cape Fear River system.It empties directly into the AtlanticOcean, has a one-meter tide, and hasextensive areas of typical tidal freshwatermarshes.South Carol ina and Georgia containnunierous and often extensive tidal freshwatermarshes. Many of these marshes andassociated swamps were diked, impounded,and converted to ricefields during thelath and first half of the 19th centuries.Sorne of these impoundments remain virtuallyintact. However, in others the dikeshave broken and the impoundments havereverted to tidal marsh. A difficultinanagement decision needs to be made as towhether the i ntdct impoundments should bernanaged for ~aterfowl or should be allowedto revert to tidal marsh (discussed inChapter 9).The mos t southern major river sys temon the coast, the St. Johns River inFlorida, has tidal influence for over 160kilometers (99 mi) inland (L. Gerry, Jacksonville Water Control District, Pal atka,Florida; pers. comm.). Due to its unusualmorphology (narrow mouth, broad upperreaches), the tidal amp1 i tude in the tidalfreshwater stretch is ninor, and typicalplant communities are absent or restrictedto small areas.Tidal freshwater envi ronments (includingsome mangrove areas) exist insouth Florida. However, they are generallytoo restricted in size or too seasonalin occurrence (e.g., the Evergladesestuary) to be included in this report.Similar types of tidal freshwatermarshes occur on other coasts of theUnited States. For example, Louisiana hasextensi ve stretches of tidal, freshwaterwetlands. However, these wetlands have atide that is irregular, of low amp7 i tude,and wind driven. This makes both the community structure and ecosystem processesappear to be somewhat different (Chabreck1972; Hopkinson et al. 1978). Tidalfreshwater marshes are relatively rare onthe Pacific coast. They do occur extensively,however, in Alaska (McRoy andGoering 1974), in California in associationwith several large river systemsincluding the Sacramento (Kelley 1966),and between Washington and Oregon in associationwith the Columbia River.(Clairain et al. 1978).1.3 VISUAL APPEARANCETidal freshwater marshes look stri k-ingly different from either salt marshesor nontidal freshwater marshes. Plantdiversity is much higher than that foundin higher salinity estuarine marshes. Theresult is a highly heterogeneous plantassembl age (Figure 3) quite different inappearance from the almost monospecif icSpartina marshes found nearer the mouth ofthe estuary. Zonation is oresent (discussedin Chapter 2) but is not assharply defined as in salt marshes. Theso-called low marsh is dominated by a fewbroad-leaved, fleshy plants such as spatterdock(Nuphar luteum) and pickerelweedand by wild ricemania aquatica) andgiant cutgrass (Zizaniopsis mil iaceae).The higher sections of the tidal freshwatermarsh contain aore species than thelow marsh and may be dominated by a varietyof plants including cattail (Typhaspp. ), smartweeds (Pol onums spp.) , rosemallow(Hibiscus moscheutos -7 , sweet flaq(Acorus calamus), and burrnarigold (Bidens . x Certain species such as arrow-arumare found throughout the marsh.The tidal freshwater marsh has plantsin flower through much of the spring andsummer. In the spring wild iris (Irisspp.) blooms in the high marsh. In earlysummer, pickerelweed sends up a spike ofpurple flowers. Rose-ma1 low, jewel weed(Impatiens capens is), and the spectacularyellow flowers of burmarigold bloom laterin the summer.One of the most striking features ofthe tidal freshwater marsh is the pronouncedseasonal sequence of vegetation
Figure 3,Tidal freshwater marsh on the Chickahominy River, Virginia, during midsummer.(discussed at length in Chapter 2). The1 ow marsh undergoes particularly extremechanges. There is a period of virtuallybare mud in late winter and early spring.Then there is a period of domination bybroad-leaved plants (e.g.,arrow-arum) inthe late spring, and finally in late summerthere is a period dominated by grassesand herbaceous pl ants ( Figures 4a ,b) .Conspicuous organisms in the tidalfreshwater marsh include freshwater snakesand turtles, adult and larval insects,ducks and geese, and muskrats. A casualexamination of the fauna of the tidalfreshwater marsh reveals few bivalves,crustaceans, or polychaetes, organi smswhich dominate the higher salinity marshesin the lower estuary.In summary. the tidal freshwatermarsh appears superficially different fromthe nearby salt marshes. In Chapter 10 wediscuss whether these apparent differencesactually exi'st and whether they includeaspects of communi ty structure and ecosystanprocesses.1.4 HORIZONTAL , TEMPORAL, AN0 REGIONALVARIATIONSTidal freshwater ecosyste~?~ form acomplex gradient with freshwater on oneside and 01 igohal ine and higher salinityesturine conditions on the other side.Concentrations of dissolved oxygen, particulateand dissol ved carbon, dissolvedheavy metals, nitrite, nitrate, ammonia,and other chemical and physical water andsediment parameters change dramatically assalinities increase from 0.1 to 1.0 ppt(Morris et al. 1978). Fish, plant, andinvertebrate communities change si gnif i -cantly as the salinity rises above 1 p ~t.Rarely are conditions homogeneous over avery great distance. For this reason,general statements about ti dal freshwatermarshes and associated bodies of watermust always be made with gradient conditionsin mind.Tidal freshwater wet1 ands vary temporally as well as spatially. Daily, seasonal,and long-term changes may occur ata given site in response to tidal or windinfluences and as a result of annual or
Page 2 and 3: LibraryNational Wetlands Restarch C
Page 4 and 5: PREFACEThis report is part of a ser
Page 6 and 7: Page.......6.1 Species Composition
Page 8: TABLESNumber12345678910111213141516
Page 13 and 14: (DURINGLowFLOWCONMTIONS)Figure 1. T
Page 15: MERRIMACK RlVERNORTH RlVERCONNECTIC
Page 19 and 20: In general the river systems of the
Page 21 and 22: and Powers (1978) measured the cati
Page 24 and 25: CHAPTER 2, COMMUNITY COMPONENTS: PL
Page 26 and 27: Table 4.Common species of vascular
Page 28 and 29: Nyssa sylvanticaN~s;;~;;uaticaMediu
Page 30 and 31: progresses, some pl ants wi 11 be o
Page 32 and 33: many of the tidal freshwater marshe
Page 34 and 35: Rose-Mallow \i':JewelweedFigure 10.
Page 36 and 37: able physiognonies in this species
Page 38 and 39: 2.4 FACTORS CONT3OLLIVG PLANT DEMOG
Page 40 and 41: Table 5. Species composition of fiv
Page 42 and 43: of sorne form (e.g . , major commun
Page 44 and 45: naiads, wild celery, and dwarf arro
Page 46 and 47: govern the seasonal blooms and succ
Page 48 and 49: CHAPTER 3. ECOSYSTEM PROCESSES3.1 P
Page 50 and 51: Table 7. Continued.Peak standing cr
Page 52 and 53: ing the sampling effort to just one
Page 54 and 55: and completely decompose in 4 to 5
Page 56 and 57: SOURCES(LARGELY INORGANIC, OXIDIZED
Page 58 and 59: is an approximate 100% turnover of
Page 60 and 61: solved carbon as particulate carbon
Page 62 and 63: polychaete, Scolecol epides viridus
Page 64 and 65: 4.3 MARSH PLANT INSECT COMMUVITYPub
Page 66 and 67:
minnows occupy midwater and benthic
Page 68 and 69:
Tab1 e 11.Characteristics of anadro
Page 70 and 71:
Figure 24. Striped bass, the most i
Page 72 and 73:
Table 13.Numerically dominant fishe
Page 74 and 75:
- Table 15. Fishes using tidal fres
Page 76 and 77:
to the ocean. The freshwater reside
Page 78 and 79:
Lizards and 1 izard-1 ike reptiles
Page 80:
Tab1 e 17. Efficiency of secondary
Page 83 and 84:
The birds of tidal freshwater wetla
Page 85 and 86:
Table 18. Distribution of waterfowl
Page 87 and 88:
Table 29. Breadth of diet of select
Page 89 and 90:
other rails) gather to feed on the
Page 91 and 92:
the effects of seabirds on nutrient
Page 93 and 94:
the various soecies of mammals in t
Page 95 and 96:
h?ve not been directly studied. Stu
Page 97 and 98:
CHAPTER 9- VALUES, ALTERATIONS, AND
Page 99 and 100:
estuary to the rlext dependinq upon
Page 101 and 102:
Section 3.3). Simpson et al. (1981)
Page 103 and 104:
Tab1 e 24. Hypothetical comparisons
Page 105 and 106:
Table 24.Concluded.Characteristics
Page 107 and 108:
REFERENCESAdams, D.A. 1963. Factors
Page 109 and 110:
J.E. Clark eds. Wetland functions a
Page 111 and 112:
Sci. Rep. 40.4. Nat. Resour. Inst.U
Page 113 and 114:
University Press, Ithaca, N.Y.345 p
Page 115 and 116:
fish fauna of Tivoli Bays. Bard Col
Page 117 and 118:
Patrick, eds. Two studies of Tinicu
Page 119 and 120:
Sci . 16:77-78.Penney, J.T. 1950, D
Page 121 and 122:
Smith, B.A. 1971. The fishes of fou
Page 123 and 124:
R.L. Simpson, eds. Freshwater wet1
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APPENDIX APlants of the Tidal Fresh
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PontederiaceaePontederia cordataZos
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Ona graceaeJossiaeare~en~LudwuriaDa
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APPENDIX BFISH OF TIDAL FRESHWATERS
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Amiidae -bowfins&Labrvf inElopidae
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Geographic Salinity Relativerange r
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NameCatostomidae -suckersGeographic
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Name GeographicrangeSalinityrangeRe
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NameGeographicrangeSalinity Relativ
Page 144:
Centrarchidae -sunfishesName Geogra
Page 147 and 148:
Percidae -perchesEtheostomafusiform
Page 149 and 150:
Name Geographic Salinity Relativera
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Reference Numbers Key1. Adams 19702
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l m L o .Arl- >4J 3o m uc, mEU mmm
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Family / SpeciesRegionStatusFood ha
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- fIn-f W--7.40 -> 0171- Lw m mUtu
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APPENDIX D:Avifauna of tidal freshw
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Hooded merganser(LoDbodvtes-)Common
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FamilySpeciThreskiornithidae - ibis
Page 167 and 168:
Family / SpeciesRegionSeasonStatusH
Page 169 and 170:
Cathartidae - vulturesRegionDIURNAL
Page 171 and 172:
CULLS, TERNS, KINGFISHERS, AND CROW
Page 173 and 174:
ARBOREAL BIRDSFamily / Species Regi
Page 175 and 176:
Family / Species Region Season Stat
Page 177 and 178:
Family / Species Region Season Stat
Page 179 and 180:
Family / Species Region Seasonnorth
Page 181 and 182:
Family / SpeciesMarsh wren(Long-bil
Page 183 and 184:
drQFamily / SpeciesFringilidae - fi
Page 185 and 186:
APPENDIX E:Mammals of tidal freshwa
Page 187 and 188:
Family / SpeciesRegionStatusFood ha
Page 189:
50272 -to1 1REPORT DOCUMENTATION2.3
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