Amazonian Mangrove Dynamics During the Last Millennium: the Relative Sea-Level and the Little Ice Age* 2 1 1 2 2 Federal University of Pará, Brazil Cohen, M

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Amazonian mangrove dynamics during the last millennium: The relative sea-level and the Little Ice Age* 2 1 1 2 2 Federal University of Pará, Brazil Cohen, M. C. L. , Behling, H. , Lara, R.J. Center for Tropical Geology Department Marine Ecology 1 Laboratory of Coastal Dynamics, Federal University of Pará, Belém, Brazil 2 Center for Tropical Marine Ecology (ZMT), Bremen, Germany

Introduction Results There is evidence that the sea-level has increased since the end of the Little Ice Age (Figure 1; Based on the pollen analyses of the nine sediment cores (Figure 2) a pollen profile was Ekman, 1999). The resulting global mean sea-level rise of about 18 cm during the last century composed, which shows the zones of different paleo-vegetation types (Figure 4). The (Gornitz, 1995) has produced displacements of coastal ecosystems (IPCC, 1996; Crooks and Turner, combination of stratigraphic sequences and pollen records obtained from mangrove 1999). In Brazil, tidal records obtained over the last 50 years show a general rise in relative sea-leve deposits provides some insight into the interaction between climate and inundation regime (Pirazolli, 1986; Silva, 1992; Aubrey et al., 1988). . changes. While changes in the sediment grain-size probably imply an adjustment in the The effects of this sea-level on the Brazilian coastline seem to be reflected particularly by sediment transport energy in mangroves, the pollen assemblage may indicate changes in shore erosion (Muehe and Neves, 1995). Southeast of the Amazon River mouth, a significant part of rainfall rates and/or inundation frequency changes in mangroves. elevation related CS to mean sea-level Palaeo-environmental units the Pará State coastline (Figure 2) has undergone a net loss of mangrove coverage area during the S 250 mangrove P1 hypersaline tidal flat P2 N cm P2 last 25 years. On the other hand, mangroves have invaded herbaceous flats at higher elevations 42420 cal BP M9 M5 P2 herbaceous plain C1 sand flat 180 cal BP during same period (Figure 3; Cohen and Lara, 2003). . P2 M6 M7 P2 P2 M8 200 M1 510 cal BP 200 >1950 AD P1 Increasing greenhouse gas concentrations are thought to be the dominant forcing factor of M2 440 cal BP cm M4 P1 M3 P1 950 cal BP P1 climate change over the last decades (IPCC, 1996), driving temperatures to unprecedented levels 420 cal BP 800 cal BP 150 390 cal BP 150 (Bradley, 2000), and resulting in varying predictions of rising sea-level rates of +15 cm by the year P1 820 cal BP C1 2050 and of +35 cm by 2100 (Titus and Narayanan, 1995). More recent predictions indicate a sea- ? W P1 C1 C1 m 4 k 4 100 k 100 level rise between 60 and 100 cm by the end of this century (Douglas et al., 2000). P1 m C1

Also pre-industrial surface temperatures mangrove herbaceous plain herbaceous plain mangrove ) º C

varied significantly, probably provoked by ( 1500 1250 1000 500 1000 1250 1500 1750 m 0 m e

g Figure 4- Composition of pollen profile from study site (Cohen et al. 2005). fluctuations of solar activity levels, which n Little Ice Age a h

C Conclusions produced relatively cold periods during the e r u Little Ice Age (LIA) (Lean and Rind, 1999). t This study suggests two periods of low tidal inundation frequency (P1 and P2), which a

r Medieval e The conventional view of the climate p Warm Period probably occurred between 1130 and 1510 AD; and 1560 AD and the end of the 19th m e

history of this period has been traditionally T century, respectively (Figure 5). Likely, this alternation of dry and wet sediment based on European weather records, 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 conditions is coupled with relative sea-level changes. The pollen records also indicate that Calendar Years (A.D.) delineating two distinct time periods, the mangroves on the Bragança Peninsula have migrated to higher elevated zones during the Figure 1 - Qualitative view of global temperature LIA and the preceding Medieval Warm variations during the last thousand years. last decades, as also revealed by the time series analysis of satellite images (Figure 3), Period (Figure 1). suggesting a relative sea-level rise. . It is not clear whether the conception of the “Little Ice Age” derived from the Northern The P1 and P2 events appear to be temporally correlated with an erosional period in the Hemisphere is applicable to the Southern (Grove, 2001). In northern Brazil, the LIA effects might Amazon shelf, the dry climate in South America and the LIA period represented by be recorded on the coastal zones, since over 80% of sediments of the Amazon River discharge is glacier advances in Europe, North America and Andes. The present mangrove migration derived from the Andes (Gibbs, 1977), and the sediment transport of the Amazon River has can be associated with the global tendency of an eustatic sea-level rise, due to the produced the longest mud coastline in the world (Kjerve and Lacerda, 1993). This coastline is increase in temperature and glaciers melting around the world during the last 150 years. colonized by mangroves, which are considered highly susceptible to sea-level fluctuations and depositional conditions depositional erosional phase (Sommerfield et al., 1995) climatic changes (Gornitz, 1991). . for the Amazon shelf phase 46º39’W Amazon River

1. 70 The purpose of this paper cold and dry (Arg.) cold and dry (Arg.) (Cioccale, 1999) 1. 7 BRAGANÇA 0

is to study the environmental 0

Brazil 4 8 cold and dry (Venez.) (Iriondo, 1999) 1 . ’ 7 S history of the Bragança 0 BELÉM Peninsula during the last 1000 sea level (m) dry (Colombian Andes) dry (Col. Andes) (Eisma et al., 1991)

years, focusing in the vegetation 2 3 dry period, P1 (Bragança) dry period, P2 (Bragança) 0 development in the central M9 2 3 0 0.5 part of the peninsula, where 0

0 0

boundaries of mangrove and 0

. . .3 . .30 2 1000 2 2 1100 1200 1300 1400 1500 1600 1700 1800 1900 M8 M7 2.60 - salt marshes occur, and M6 0.5 M5 Calendar Years (AD) sensitive vegetation changes CS ----*------*------related to relative sea-level M1 0 ** 7 . M2 1 ------M3 -1 .5 ** changes can be expected. Thus, M4 ---***------1. 70 Caeté Bay * * * * 2 km 70 0 1. 2.00 3 -----glaciers advance propose the LIA-effects in 2 worldwide location of the sediment core - *Alaska (Calkin et al., 2001), Southern Hemisphere on the 2.5 glacier Vegetation and landscape units **Canadian Rockies (Luckman, 2000) , 3 km paleo sea-level basis of changing mangrove Herbaceous mangrove retreat plain Bragança ***Andes (Iriondo and Kröhling, 1995), coastal distribution. The approach used restinga Amazon degraded sandy plains, ****Switzerland (Röthlisberger et al, 1980) plateau coastal dunes and beaches Marajo Island (Behling et al., 2004) stratigraphy, polle analysis coastal forest mangrove Figure 5- Comparative diagram between some LIA records, and the hydrologic and paleovegetation and radiocarbon dating. Figure 2- Topographic map from Bragança Peninsula with the sediment core position and vegetation units (Cohen et al. 2005). characteristics from Bragança Peninsula over the last 1000 years BP (Cohen et al. 2005). !References !Aubrey, D.G., Emery, K.O., Uchupi, E., 1988. Changing coastal levels of South America and the Caribbean region from tide-gauge records. Tectonophysics 154, 269-284. !Behling, H., Cohen, M.C.L., Lara, R.J., 2001. Studies on Holocene mangrove ecosystem dynamics of the Bragança Peninsula in north-eastern

DEGRADED MANGROVE ! ROAD Pará, Brazil. Palaeogeography, Palaeoclimatology, Palaeoecology 167, 225-242. !Behling, H., Cohen, M.C.L., Lara, R.J., 2004. Late Holocene mangrove dynamics of the Marajó Island in northern Brazil. Veg. Hist. And Archaeobotany 13, 73-80. MANGROVE !Bradley, R.S., 2000. Past global changes and their significance for the future. Quaternary Science Reviews 19, 391-402. Fig. 3a !Calkin, P.E., Wiles, G.C., Barclay, D.J., 2001. Holocene coastal glaciation of Alaska. Quaternary Science Reviews 20, 449-461. !Cioccale, M.A., 1999. Climatic fluctuations in the Central Region of Argentina in the last 1000 years. Quaternary International 62, 35-47. !Cohen, M.C.L., Lara, R.J., 2003. Temporal changes of mangrove vegetation boundaries in Amazônia: application of GIS and remote sensing

HERBACEOUS FLAT techniques. Wetlands Ecology and Management, 11: 223-231. !*Cohen, M.C.L., Behling, H., Lara, R.J. 2005. Amazonian mangrove dynamics during the last millennium: The relative sea-level and the Little Ice Age. Review of Palaeobotany and Palynolog, 136: 97-112. !Crooks, S., Turner, R.K., 1999. Integrated coastal management: sustaining estuarine natural resources. Ecology Research 29, 241-289. MANGROVE !Douglas, B.C., Kearney, M.S., Leatherman, S.P., 2000. Sea Level Rise, History and Consequences. Academic Press. Vol. 75, pp. 416. !Eisma, D., Augustinus, P.G.E.F., Alexander, C.R., 1991. Recent and subrecent changes in the dispersal of Amazon mud. J. Sea Res. 28, 181-192 Fig. 3d !Ekman, M., 1999. Climate changes detected through the world's longest sea level series. Global and Planetary Change 21, 215-224. Fig. 3b Fig. 3c !Gibbs, R.J., 1977. Clay mineral segregation in the marine environment. Journal of Sedimentary Petrology 47, 237-243. !Gornitz, V., 1991. Global coastal hazards from future sea level rise. Palaeogeography, Palaeoclimatology, Palaeoecology 89, 379-398. 00º 40’ S MAIAÚ ! ISLAND BOIUÇUCANGA Gornitz, V., 1995. Sea-level RSC: a review of recent past and near future trends. Earth Surface Processes and Landforms 20, 7-20. ISLAND !Grove, J..M., 2001. The initiation of the “Little Ice Age” in regions round the North Atlantic. Climatic Change 48, 53-82 MANGROVE MAIAÚ ROAD !IPCC, 1996. Second Assessment Report: Climate change: The Science of Climate Change. Cambridge Uni. Press, Cambridge, UK. BAY !Iriondo, M., Kröhling, D., 1995. El Sistema Eólico Pampeano. Com. Museo Prov. Ciencias Naturales 5, 1-80. DEGRADED MANGROVE !Kjerfve, B., L. D. Lacerda., 1993. Mangroves of Brazil. pp. 245-272. In: Conservation and Sustainable Utilization of mangrove Forests in

MANGROVE Latin America and Africa Regions. L. D. Lacerda (ed.). ITTO/International Society for Mangrove Ecosystems. Okinawa, Japan. 272 pp. Fig. 3e !Lean, J., Rind, D., 1999. Evaluating sun-climate relationships since the Little Ice Age. J. of Amosp. and Solar-Terrestrial Physics 61, 25-36. !Luckman, B.H., 2000. The Little Ice Age in the Canadian Rockies. Geomorphology 32, 357-384. Mangrove !Muehe, D., Neves, C.F., 1995. The implications of Sea-level Rise on the Brazilian Coast: A Preliminary Assessment. J. C. R. 14, 54-78 Mangrove area gains !Pirazolli, P.A., 1986. Secular trends of relative sea levels (RSL) changes indicated by tide-gauge records. J. C. R., Special Issue 1, 1-26. Mangrove area losses !Röthlisberger, F., Hass, P., Holzhauser, H., Keller, W., Bircher, W., Renner, F., 1980. “Holocene climatic fluctuations radiocarbon dating of “Terra firme” vegetation fossil soils (fAh) and woods from moraines and glaciers in the Alps”, in Geography in Switzerland, Geographica Helvetica 35, 21-52.

’ ! W

5 Silva, G.N., 1992. Variação do Nível Médio do Mar: Causas, Consequências e Metodologia de Análise. M.Sc. Thesis. Programa de

’ Herbaceous flat

º 0

6 º Degraded mangrove Engenharia Oceânica, COOPE. Universidade Federal do Rio de Janeiro. 93 pp.

7 4 0 km 5 km !Sommerfield, K.C., Nittrouer, C.A., Figueiredo., 1995. Stratigraphic evidence of changes in Amazon shelf sedimentation during the late Figure 3: Evolution of coastal vegetation according to the analysis of RADAR and satellite images ! Holocene. Marine Geology, 125: 351-371. covering an 25-year period (1972-1997). Figures 3a, 3b, 3c, 3d and 3e: aerial photographs of the !Titus, J.G., Narayanan, V.K., 1995. The probability of sea level rise. United States Environmental Protection Agency, Office of Policy, ! Planning, and Evaluation (2122), EPA 230-R-95-008, Washington, DC, 186 pp. inner and outer mangrove (Cohen and Lara 2003).