Hydrokcol. Appl. (1991) 1, pp. 111 - 124

Petit-saut hydroelectric scheme : vegetal associations of stagnant waters in French

(1) Laboratoire d'Hydrobiologie, Universit4 de Provence, Centre St Charles, Place V. Hugo, F- 13331 MARSEILLE Cedex 3. (2) Laboratoire d'Hydrobiologie Marine et Continentale, Universite de Montpellier II, Case 093, Place E. Bataillon, F-34095 MONTPELLIER Cedex 5. (3) E.D.F., Direction Equipement, Service I.D.E., 22-30 Avenue de Wagram. F-75382 PARIS Cedex 08.

Surnrnary. - Hydroelectric of Petit Saut is under construction on the river Sin- namary in French Guyana. The future reservoir will flood a 300 km area of virgin forest. Under tropical climate as in Brazil or Surinam, the reservoirs are often overgrown with macrophyte vegetation during several years from the start of flooding operations. In order to assess the risks of vegetal proliferations in the future reservoir of Petit Saut, rnacrophyte lists have been made out with special attention to some prolific species ( crassipes, Salvinia auriculata, Pistia stratiotes, Oxycariurn cubense, etc.) in al1 types of aquatic environments (marshes, ditches, canals, ricefields, etc) by using phytosociological method (abundanceldorninance indice). A correspondence analysis of data have perrnitted to show the relationships between specific vegetal communities and typical water environments. The spatial distribution of the macrophyte communities in these various environments according to their limno- logical features constitute a starting point for devising the mean to limit their proliferations.

Key Words : man-made lake; macrophytes; equatorial region; French Guyana; man- agement; restoration.

RésumB. - Le barrage hydroélectrique de Petit-Saut est en construction sur la rivière Sinnamary en Guyane française. La future retenue inondera une surface de 300 km de forêt vierge. En région tropicale comme au Brésil ou au Surinam, les réservoirs sont souvent envahis par une végétation macrophytique pendant plusieurs années sui- vant la mise en eau. Afin d'évaluer les risques de prolifération des végétaux dans la future retenue de Pe- tit-Saut, un inventaire des macrophytes a été dressé en portant une attention particulière aux quelques espèces (Eichhornia crassipes, Salvinia auriculata, Pistia stratiotes, Oxy- cariurn cubense, etc.) qui prolifèrent dans tous les types de milieux aquatiques (marais, fossés, canaux, rizières, etc.). La méthode phytosociologique basée sur la prise en compte de l'indice d'abondance/dorninance a été utilisée. Une analyse des correspondances a permis de montrer la relations entre les commu- nautés d'espèces végétales et les milieux aquatiques types. La connaissance de la distribution spatiale des communautés macrophytiques expliquée par les conditions de milieu constitue un point de départ à la recherche des moyens de lutte contre leur prolifération. 112 A. Champeau, A. Vaquer et A. Gregoire

1. - INTRODUCTION the top will be leveled at 15 m below the top of the main . The hydroelectric power station of In cornparison with flumerous tropi- petit Saut is under constmdion on the cal resewoirs, the renewal time of the river Sinnamary in French Guyana. water will be relathrely short (mû ne site of the future resewoir is months) and therefore favourable to covered by the permanent amazonian Wuatic life. primary forest. 'The vegetal which will be floodd is assessd at For mn~m"reasons, the flooded about 12 millions tons carbon equiv- area will not be deforested. Con- alent. sequently, a proliferation of aquatic macrophytes is foreseeable during the Although the water intake will be first years as it is frequently observed situated close to the bottom of the in these latitudes. It follows at once lake, it will drain off water from epil- impacts of physico-chemical and bio- imnion because of a 'predam' whose logical nature. Petit-saut hydroelectric scheme 113

Table 1. - Physical and chemical characteristics of the River Sinnamary in French Guyana.

The airn of this study is to evaluate water brown-yellow. The slight quan- the importance of the risks resulting tities of nutrients are typical of from the growth of these rnacrophytes oligotrophic aquatic environments in French Guyana, in order to plan as (Table 1). soon as possible the rnost suitable means of weeds control. MATERIAL AND METHODS

THE RIVER SINNAMARY The study was carried out in 1987. A total of 294 sites examined are dis- The reservoir of Petit-Saut will flood tributed among nine geographical re- a 300 km2 area and will extend over gions (Fig. 2A) and according to six 80 km of the course of the river Sin- types of environment (Fig. 2B). These narnaty (Figure 1). regions are localized in al1 the coastal plain of French Guyana because The river Sinnamary rnay be aquatic environrnents are lacking in grouped together with the clear water the area of the future reservoir and rivers according to the current classi- its drainage basin except creeks and fication of the Amazonian rivers (Sioli, sorne borrow pits and ditches which 1975; Paiva, 1977). The water is are colonized by a very specific strongly acid and very weakly rniner- vegetation under the forest cover. pH alized. The rnost suspended particles (pHmeter), conductivity (conductime- consist of very small vegetal frag- ter), color (platina- APHA ments. colorirnetric rnethod), turbidity The hurnic acids decrease the (nephelornetric rnethod), Fe (phenan- water transparency and colour the throline colorirnetric rnethod), Ca A. Champeau, A. Vaquer et A. Gregoire

Nb. stations 80

70

60

50

40

30

20

10

0 Regina Kaw Cayenne Tonate Kourou Sinnamary Mana Iracoubo St Laurent

Nb. stations

Flooded Crecks Marshes Canals Borrow pits Ditchcs savannahs

Fig. 2. - Frequencies of dations according to geographicai area (A) and the different aquatic environments (B). Petit-saut hydroelectric çcherne 115

(EDTA complexometry method), and 75-100 % of the vegetated area) as sum of am- and a sociability index (1-6) indicating monium-N (Nessler method), nitrate- the distribution pattern of in the N (naphthtylamine colorimetric site (1-isolated individuals to 6-totally method) and nitrite-N (diazotation clustered) were associated to each and naphthtylamine colorimetric observed species. method) were measured as much as possible. The original phytosociological data set (294 observations x 104 species) The vegetation was studied ac- was reduced to 275 observations x cording to classical phytosociological 76 species by removing species ob- methods. In each site, a floristic list served in less than 1 O/O of the sites was drawn up. Plants were identified and sites under forest and analyzed according to Lemee (1952-1 956), using Correspondence Analysis. Cook (1974), Fournet (1978), Gopal Cornputations were performed using (1987). An abundance index (1-6) ex- BIOMECO Program (v.2.0, 1987, pressed as cover abundance (< 1 %; Groupe BIOMETRIE du CEPE-CNRS; 1-1O %; 10-25 %; 25-50 %; 50-75 % F-Montpellier).

Table 2. - Physical and chemical characteristics of waters in the different aquatic en- vironments in the littoral area of French Guyana. (N = number of measures; S.d. = Standard Deviation). 116 A. Champeau, A. Vaquer et A. Gregoire

RESULTS are hydrophytes (typical aquatic plants, free-floating, rooted, entirely

submersed). 59 Oh of the species The main physico-chemical features have been observed at the most in of water sites surnmarized in Table 2 10 stations. Seven plant species indicate that borrow pits and flooded were present in over 40 stations and savannahs are in general very soft three grew in a station out of 3 environments. In contrast canals and (Fig. 3). The specific richness is ditches are much more rnineralized. very variable between stations, from The slight values correspond to sorne 1 to 21 species by station. The two ditches of the interior. Marshes and thirds of the prospected aquatic en- creeks are characterized by large vironrnents were colonized by 2 to ranges of variation of the measured 8 macrophytes (Fig. 4). The analy- parameters. Sorne sites are in- sis of data being collected in al1 sites fluenced by saline coastal waters. indicate 30 to 40 plant species rela- The floristic list is cornposed of tively abundant. All the macrophytes 104 taxonomic units (Annex l), being considered as nuisance have belonging to 36 farnilies and 61 been observed, but their distribution genera. The farnilies Cyperaceae and are very inequal. For exarnple, Gramineae group respectively 24 % Echinochloa, Oxycarium and and 20 O/O of the species. 65 % of the Salvinia are present uniformly in al1 species are helophytes (with erner- the littoral area. The distribution of gent andlor stems) and 24 % these species results from their

Nb. species

0/10 10120 2(~/3(J 30140 40/51i 50160 h0170 70180 XODO g(Jl1MJ 100/1 10

Fig. 3. - Frequenaes of the plant species according to the number of their observations. Petit-saut hydroelectric scheme 117 ! Nb. Stations 80

70

60

50

40

30

20

10 Nb. species

0 I i 012 2/4 416 618 8/10 10112 12/14 14/16 16/18 18/20 20122

Fig. 4. - Frequencies of the observation stations according to the number of plant species.

tolerance as regards to main en- All these species are present in the vironmentalparameters.Thedevelop- regions bordering French Guyana. ment of Salvinia should be The distribution of Eichhornia in the contained by low conductivity levels regions of Kaw and Mana corres- (< 60 yS cm-1; Junk, 1982). In con- ponds to relatively high abondances trast, Pistia and Eichhornia are pre- in the bordering regions of Brazil and sent in limited areas. Data about Surinam (Gopal, 1987). Oxycarium, sites being colonized by Pistia are abundant in Brazil and frequent in too scarce and do not permit to dis- French Guyana, is more scarce in cuss its distribution. In the other Surinam (Jonker Verhoef, 1968). hand, several factors can explain the development of Eichhornia in a The results from the corres- few stations. This develo~ment pondence analysis of data clearly in- COU^^ be controled by ~OWvalues of dicate the discrimination between PH (< 5; Berg, 1961), low COt-~en- types of aquatic environments and trations of nitrogen (Chadwick & their floristic communities. The posi- Obeid7 1966) and above al1 by 100 tioning of the sites and the species low concentrations of calcium (Oki on the first ordination diagram et al., 1978; Desougi, 1984) as (axis 1*2) indicating an important being measured in nurnerous sites, Guttman effect, the axis 3 bas been particularly in borrow pits, flooded examinated. The positioning of the savannahs and creeks. sites on the ordination diagram A. Champeau, A. Vaquer et A. Gregoire

lxx. Freshwater marshes l O X . Savannahs ex rix lx. r x x xm XX X X ; . ox,~.-i-O. O .P.. ~.-xX-rx~Xx -" O O x. @rx.* X'x x 0 , X OX' o. FI l @O< X X- . xX .O + x Ilitches and canals -. 0 O . .O . O O O . 00. O Creeks . - O

Fig. 5. - Correspondence analysis. Positioning of the different aquatic environments in ordination diagram, axis 1'3.

F3 1 Cyperus ariiculalur Ludwigia leplocarpa II Fuirenu umbellara Blechnum srrrululum 19 Rhynchospora hr)loschuenoi&s 97 Rhynchospora coryrnboso

I ~yphun~usiifo~ia Elecichuris Eleuchuris Acrostichwn uurrum parpuiwn so~olii Polygonum Panicum virgalum 97 1 Lerr.iia W~lfiella AZO//U purviflorum C. huspun .T&r~u Pislia lr(~liol~,T 1'9 Eleochuris Limnobiurn sroluniferum Lindernia II inlersiincm Eichhurnia Cru.isipes Rhynchospora Nympheu rudg-

Fig. 6. - Correspondence analysis. Positioning of the çpecies in ordination diagram, axis 1'3. Petit-saut hydroelectric scheme 119

(axis 1*3; Fig. 5) indicates a gradient cies were never obsewed as co-dom- on the axis 1 from flooded savannahs inant in this study. to ditches and canals. This gradient Marshes (facies 2) being caracter- could represent the evolution from ized by Eleocharis interstincta and temporary, natural and soft, aquatic Rhynchospora corymbosa are very environments to permanent, often ar- frequent in French Guyana. They tificial and more mineralized, aquatic were also observed by Lindeman in environments. Freshwater marshes Surinam and Guyana. In strongly min- are in intermediate position. The axis eralized marshes deep water zones 3 could discriminate permanent and are colonized by Nymphea ampla, temporary stagnant waters in opposi- Azolla and Lemna minor as it was ob- tion of slowly running waters (creeks). served by de Granville (1976). Creeks and borrow pits under for- est cover are not considered in this analysis. ~heyform a particular group Weed control of sites, with poor lists of macrophytes dominated by Thurnia. The discri- Owing to the distribution of the mination of these different aquatic aquatic macrophytes in French Guy- environments corresponds with dis- ana and their preferences for the main tinguishing groupments of plants limnological features, Oxycarium, (ordination diagram, Fig. 6). The Echinochloa, Salvinia and Eichhornia axis 1 separates the helophytes in in a lesser extent seem to be the main negative position from hydrophytes probable proliferating macrophytes in which form floating mats (Leersia, the future man-made lake. Because Oxycarium, Echinochloa, Polygonum, of the risks of invasion of the future etc.) in marshes and artificial environ- lake by weeds and their economical ments and from floating hydrophytes and ecological implications, it is very (Wolfiella, Azolla, Pistia, Eichhornia, important to think about the means to etc.), often in environments under control their development. human influence. Chemical control have been at- The examination of floristic lists in tempted particularly against water hy- the different types of environment and acinth. 2,4-D was the most used the ordination of the sites and species herbicide, but showed important side allow to distinguish different communi- effects because of its brutal and rapid ties being caracterized by dominant action (Leidermann & Figueiredo, species and associated plants 1967; Philipp et al., 1983). Some (Table 3). more progressive herbicides as gly- Marshes (facies 1) caracterized by phonate are less detrimental for en- Typha angustifolia and Cyperus artic- vironment (Pieterse & Rijn, 1974). ulatus are quite similar to marshes Nevertheless herbicide mixtures are being described in Surinam by Lin- in general better than a product alone deman (1953), although these spe- because of their large sphere of ac- Table 3. - Dominant species and associated plants observed in the different water environments of the littoral area of French Guyana. . - Environments Dominant species Associated species Associated species

Scirpus maritimus - Eleocharis mutata Acrostichum aureum ToruRum fera Brackish marshes - ~~~h~~r~~~a Paspalum vaginatum - Sporobolus virginicus Ludwigia leptocarpa - Typha angustifolia Lemna Fuirena umbellata - Cyperus haspan Nymphes Freshwater marshes Typha angustifolia - Eleocharis sagotii Cyperus polystachios - Leersia hexandra Utricularia sp. (Facies 1) Cyperus articulatus Paspalum virgatum - Panicum parviflorum Rhynchospora corymbosa Salvinia auriCulata l Fuirena umbellata - Cyperus haspan Freshwater marshes 1 Eleocharis interstincta Rhynchospora wrymbosa - Leersia hexandra Mayaca longipes (Facies 2) ! Rhynchospora corymbosa Scleria microcarpa - Rh. holoschoenoides Myriophyllum spicatum Montrichardia arborescens - Lindernia Panicum mertensii Cyperus giganteus Freshwater marshes Montrichardia arborescens - Utriculana sp - Wohîella sp Polygonum acuminatum (Facies 3) Blechnum serrulatum Salvinia auriculata - Limnobium stoloniferum Pistia stratiotes Paspalum virgatum - Panicum parviflorum Heliconia psitfacorum - Fiooded savannahs Rhynchospora cyperoides - Lindernia Eleocharis interstincta Mayaca - Myrophyllum - Cyperus haspan - Rh. holoschoenoides Fuirena umbellata - Nymphoides indica Utricularia Cabomba aquatica - Montrichardia arborescens Creeks Pistia stratiotes Limnobium stoloniferum Salvinia auriculata - Wolfiella - Utricularia Water environment in forest (in general ThUrnia Tonina fluviatilis creeks or borrow pits, Eichhornia crassipes - Eichhornia azurea Canais (artificialwater Polygonum acuminatum Salvinia auriculata - environments, as EchinOchloa polystachia - Oxycarium Wolfiella bense Leersia hexandre - Polygonum acuminatum ricefields...) Limnobium stoloniferum Pistia stratiotes - Azolla Nymphea rudgeana Utricularia Rhynchospora cyperoides Fuirena umbellata Borrow pits - Salvinia - Tonina - Eleocharis interstincta - Nymphea Cabomba - Wolfiella ~electricscheme 121 tivity. They could allow to dirninish the those of the reservoir of Tucurui on quantities of each herbicide (Widy- the river Tocantins in Brazil (M.F. de anto et al., 1979). Oliverra Filho, Centro de Protecao Varied rnethods of biological con- Arnbiential, U.H.E. Tucurui, oral trol have also been atternpted essen- cornrn.) where only about 10 % of the tially against water hyacinth (Bennett, surface is covered by floating mats, 1984; Wright & Center, 1984). Her- this rnethod could be preferred owing bivorous fishes (Lasher, 1967, Sutton, to the best environrnental conserva- 1977), turtles (Carr, 1952; Tonopi & tion. Varghese, 1983), insects Coleoptera and Orthoptera (Bennett & Zwolfer, 1968; Forna & Bourne, 1984) and CONCLUSION lamantins (Anonyme, 1983) have been introduced in diverse environ- rnents. But the results were lirnited The study of the aquatic vegetation because of the difficulties of individual in 294 sites including al1 the types of adaptation of the animal species. environrnents relatively close to the Sorne fungus as , Uredo, future reservoir indicates the high etc. have shown interesting rnorpho- probability of its colonization by logical and physiological effects on several macrophytes. The corres- hyacinth growth (Addor, 1977; Con- pondence analysis of floristic data way et al., 1979; Theriot, 1981). shows the associations of species Therefore these effects are not strong being accepted as weeds essentially enough owing to the growth capacity in permanent artificial aquatic environ- of the weeds. ments. Oxycarium and Echinochloa Mechanical digger, cutting are also seern to constitute the higher risks be- used, notably in guyanese icefields. cause of their capability to form float- But the use of these rnechanical ing mats and their distribution in al1 rnethods is unrealistic in reservoirs the guyanese aquatic environments, because of the very large extent of particularly in artificial environments. weed mats. In contrast floating mats Their development could be favoured being more often anchored on the by the very jagged shoreline allowing branches of submersed trees could their accumulation and by anchoring be destructed by controled fluctua- on the branches of summerged trees. tions of water levels: This method The growth of Salvinia which should seems to be an efficient rnean of form a floating 'pre-mat' could further weed control (Junk, 1982). the installation of this rnacrophytes. Considering the rnorphometric and In contrast, the risk of proliferation hydraulic characteristics of the future of Eichhornia crassipes seems less reservoir, i.e. strongly jagged shore- important owing to its absence in the line, relatively short renewall tirne and river Sinnamary and to its limited lo- submersed f~rrest, quite sirnilar to calization in the regions of Mana and 122 A. Champeau, A. Vaquer et A. Gregoire

Kaw. But their spread is possible in (Ed), Proc. /nt Conf. Water Hyacinth, the lake zone and their development UNEP, Nairobi, 14-40. could be favoured by mineral ele- Bennett F.D., Zwolfer H., 1968. Explora- ments and nutrients being released in tion for natural enemies of water hya- cinth in northern S. America and hypolirnnion frorn soi1 and organic Trinidad. Hyacinth Control J., 7, 44-52. matter decornposition. However the Berg A., 1961. Tôle écologique des eaux expected short renewal tirne is a de la cuvette congolaise sur la crois- favourable characteristic of the sance de la jacinthe d'eau (Eichhornia functioning of the reservoir which crassipes (Mart.) Solrns). A.R.S. O.M. could reduce the concentrations of Mémoires, Brussel, 12, 3, 1-120. these chernical parameters by leach- Carr A.F., 1952. Handbook of turtles. Comstock Publ. Assoc., Ithaca, N.Y. ing. Chadwick M.J., Obeid M., 1966. A cornpa- In expectation of the invasion by rative study of the growth of Eichhornia weeds, it is necessary to prepare the crassipes Solrns and Pistia stratiotes L. means of their control. It is known in water culture. J. Ecol., 54, 563-575. from experience that combined treat- Conway K.E., Cullen R.E., Freernan T.E., ments (chernical and biological) have Cornell J.A., 1979. Field evaluation of Cercospora rodmanii as a biological the best results. Nevertheless, the control of water hyacinth. Misc. Paper controled fluctuations of the water A-79-6. U.S. Army Engrs Waterways level allow to destruct the mats of Expt. Sta., Vicksburg, 46 p. floating plants, if the management of Cook C.D.K., 1974. Water plants of the the power plant production perrnits. In world. Dr. W. Junk (Publ.), The Hague, the assurnption of a rnoderate inva- 561 p. sion of the lake, this rnethod presents Desougi L.A., 1984. Mineral nutrient de- rnands of the water hyacinth (Eichhor- the least side effects on the environ- nia crassipes (Mart.) Solms) in the ment. In any case, it is also known White Nile. Hydrobiologia, 11 0, 99-108. frorn experience that earliness and Forna I.W., Bourne A.S., 1984. Studies in quickness of intervention always re- South Arnerica of arthropods on the duce the risks of weed proliferation. Salvinia auriculata cornplex of floating ferns and their effects on S. molesta. Bull. Entomol. Res., 75, 609-621. Fournet J., 1978. Flore illustrée des pha- nérogarnrnes de Guadeloupe et de REFERENCES Martinique. I.N.R.A., Paris, 1654 p. Gopal B., 1987. Water hyacinth. Studies 1. Elsevier Sc;. (Publ.), Addor E.E., 1977. Experirnents on bio- 471 p. control of water hyacinth with multiple Granville J.J. de, 1976. Un transect à tra- agents. Bot. Soc. Am. Publ., Misc. Ser., vers la savane Sarcelle (Mana, Guyane 154, 24. Française). Cah. O.R.S. TO.M., Ser. Anonyme, 1983. Dam the Arnazon full Biol., II, 1, 3-21. strearn ahead. Natural history, July Jonker Verhoef, A.M.E., 1968. - 1983, 60-67. ceae. In : Pulle A.A. & Lanjouw J. Bennett F.D., 1984. Biological control of (Eds), Flora of Surinam, Vol. 1 (Pt. 2), aquatic weeds. In : G. Thyagarajan E. Y: Brill (Publ.), Leiden, 81 -90. Petit-saut hydroelectric scheme 123

Junk W.J., 1982. Zur Entwicklung aqua- man Agency for Technical Cooperation, tischer Macrophyten in Curua-Una, eschborn, 224 p. dem Ersten Stausee in ZentraIamazo- Pieterse A.H., Van Rijn P.J., 1974. A pre- nien. Arch. Hydrobiol., 95, 169-180. liminary study on the response of Ei- Lasher C. W., 1977. Tilapia mossambica chhornia crassipes, Salvinia auriculata as a fish for aquatic weed control. Pro- and Pistia stratiotes to glyphonate. Me- 1 gressive Fish Culturist, 29, 48-50. ded. Fakulteit Landbouwetenschappen Lecoute P., 1947. Arrores e plantas uteis. Rijkçuniv. Gent (Belgium), 39, 423-427. Amazonia Brasileira 3. Brasiliana, Sao Sioli H., 1975. Tropical rivers as expres- Paulo, ser. 5, 251, 506 p. sions of their terrestrial environments. Leidermann L., Figueiredo P., 1967. Ex- In : Tropical ecological systems. Trends terminacao do c

ANNEXE 1.

List of the macrophytes observed in the aquatic environments of French Guyan Biological No Taxonornic units Farnily tY Pe 1 Cyperus articulatus Cyperaceae he 2 Cyperus giganteus Cyperaceae he 3 Cyperus haspan Cyperaceae he 4 Eleocharis flaccida Cyperaceae he 5 Eleocharis interstincta Cyperaceae he 6 Eleocharis mutata Cyperaceae he 7 Eleocharis sagotii Cyperaceae he 8 Eleocharis retoflexa Cyperaceae he 9 Eleocharis geniculata Cyperaceae he 10 Fimbristylis sp Cyperaceae he 11 Fuirena umbellata Cyperaceae he 12 Oxycarium cubense Cyperaceae he 13 Cyperus polystachios Cyperaceae he 14 Rhynchospora amazonica Cyperaceae he 15 Rhynchospora corymbosa Cyperaceae he 16 Rhynchospora cyperoides Cyperaceae he 17 Rhynchospora gigantea Cyperaceae he 18 Rhynchospora graminea Cyperaceae he 19 Rhynchospora holoshoenoides Cyperaceae he 20 Scirpus maritimus Cyperaceae he 21 Scirpus sp. Cyperaceae he 22 Scleria microcarpa Cyperaceae he 23 Torulinum ferax Cyperaceae he 24 Rhynchospora sp. Cyperaceae he 25 Typha angustifolia Typhaceae he 26 Andropogon sp. Poaceae 27 Bracharia sp. Poaceae he 28 Bracharia purpurescens Poaceae he 29 Echinochloa polystachia Poaceae he 30 Echinochloa sp. Poaceae he 31 Hymenachneamplexicaulis Poaceae he 32 Leersia hexandra Poaceae he 33 Oryza sp. Poaceae he 34 Panicum cyanescens Poaceae he 35 Panicum maximum Poaceae he 36 Panicum mertensii Poaceae he 37 Panicum spl Poaceae he 38 Panicum sp2 Poaceae he 39 Panicum parviflorum Poaceae he 40 Paspalum vaginatum Poaceae he 41 Paspalum virgatum Poaceae he 42 Paspalum sp. Poaceae he 43 Sporobolus virginicus Poaceae he Biological No Taxonornic units Farnily tYPe 46 Acnida sp. Arnaranthaceae - 47 Aeschynomene sensitiva Papilionaceae 49 Caperonia sp. Euphorbiaceae he 50 Crinum erubescens Amaryllidaceae He 51 Desmodium barbatum Papilionaceae 53 Heliconia psittacorum Strelitziaceae 54 Hibiscus sp. Malvaceae he 55 Hydrocotyle umbellata Apiaceae He 56 Hydrolea spinosa Hydrophyllaceae he 57 lpomea aquatica Convolvulaceae he 58 Ludwigia nervosa Onagraceae he 59 Ludwigialeptocarpa Onagraceae he 60 Ludwigia rigida Onagraceae he 61 Ludwigia sp. Onagraceae he 62 Lindernia sp. Scrophulariaceae he 63 Mimosa sp. Mirnosaceae 64 Montrichardia arborescens Araceae He 65 Neptunia sp. Mimosaceae 66 Polygonum acuminatum Polygonaceae he 67 Rhyncanthera grandiflora Melastomaceae 68 Sagittaria lanciflora Alismataceae hy 69 Sesbania exasperata Papilionaceae 70 Thalia geniculata Marantaceae he 71 Thurnia sp. Thurniaceae he 72 Vallisneria sp. Hydrocharitaceae hy 73 Xyris jupicai Xyridaceae he 74 Xyris sp. Xyridaceae he 76 Azolla sp. Azollaceae hy 77 Acrostichum aureum Adiantaceae he 78 Blechnum serrulatum Blechnaceae he 79 Ceraptoteris sp. Parkeriaceae he 80 Salvinia auriculata Salviniaceae hY 81 Thelypteris sp. Parkeriaceae he 84 Nitellopsis sp. Characeae hy 87 Cabomba aquatica Cabombaceae hy 88 Eichhornia diversifolia hy 89 Eichhornia azurea Pontederiaceae hY 90 Eichhornia crassipes Pontederiaceae hy 91 Eriocaulon sp. Eriocaulaceae hy 92 Limnobium stoloniferum Hydrocharitaceae hy 93 Mayaca longipes Mayacaceae -hy 94 Mayaca fluviatilis Mayacaceae hy 95 Myriophyllum spicatum Haloragaceae hy 96 Nymphea ampla Nympheaceae hy 97 Nymphea amazonum Nympheaceae hy 98 Nymphea rudgeana Nyrnpheaceae hY 99 Nymphoides indica Menyanthaceae he 100 Pistia stratiotes Araceae hy 1O1 Tonina fluviatilis Eriocaulaceae hy 102 Utricularia spi Lentibulariaceae hy 103 Utricularia sp2 Lentibulariaceae hy 104 Utricularia sp3 Lentibulariaceae hY 105 Utricularia sp4 Lentibulariaceae hy 106 Wolffiella sp. Lentibulariaceae hY