FRESHWATER MARSHES GEOGRAPHICAL DISTRIBUTION Diverse group - all freshwater herbaceous non-peat wetlands (usually dominated by graminoids) In Cowardin's classification: palustrine, lacustrine, riverine, persistent or non-persistent, usually emergent Lakes Floodplains Other Lake district, New Caledonia “Man-made” lake, The Netherlands Marsh in Belize Lake Atitlan, Guatemala 1 Nymphaea dominated marsh Vernal pool, Jepson prairie in Central Chile HYDROLOGY STRESS & DISTURBANCES – relatively stable along the lake coasts - anoxic conditions depends on P to ET ratio - large water level fluctuations (seasonal or longer- floodplains - size of watershed term) human impact increased sediments and nutrient load - changes in hydrology CHEMISTRY - cold temperatures nutrient input often associated with rainfall (no tides!) - human impact available N and P low during the growing season, higher in winter time Marsh cyclic development VEGETATION STRUCTURE common species: mostly emergent macrophytes but all other groups often present gradient of water depth seasonal x long-term dynamics (prairie potholes; tropical floodplains; European fishponds) zonation floating islands – flotants introduced/invasive species 2 Dry marsh Carex bohemica Lake marsh Scirpus sp. Centrifugal organization Wisheu & Keddy, 1992, J. Veg. Sci 3: 147 Biomass and species richness (Grime 1979; Keddy 1990) SPECIES RICHNESS SPECIES BIOMASS STRESS Yellow billed stork, Mycteria ibis Invasive species Red lechwe, Kobus leche FAUNA Invertebrates: molluscs, crustacean, insects Fish, birds, mammals Purple loosestrife Lythrum salicaria 3 FUNCTIONS FLOODPLAINS Primary production - Floodplains of large rivers are among the most productive ecosystems - depends on temperature, soil and water fertility, degree of flooding - among the first to be altered by economic development and human population growth (direct change – agriculture, settlement x - high NPP correlated with high leaf area index changes in river hydrology (dams) - % of belowground increases with latitude - early all of the major floodplain rivers in the Northern Hemisphere - biomass vs. species diversity (and many in the Southern) have beenleveed or impounded for navigation, power generation or flood control - only large rivers of the far north and some tropical rivers offer a Decomposition view of large floodplains as they existed before human intervention - neglected by both limnologists and terrestrial ecologist (If studied Herbivory (birds, muskrats, nutrias, capybaras) then in isolation; floodplain lakes as isolated lakes, terrestrial parts as savannas or forests) SPACIO-TEMPORAL HETEROGENEITY that is CENTRAL to floodplain functioning was not considered -- important for management, protection, restoration Definition: (Junk) “Areas that are periodically inundated by the lateral overflow of rivers or lakes and/or by direct precipitation or groundwater; the resulting physico-chemical environment causes the biota to respond by morphological, anatomical, physiological, phenological and/or ethological adaptations and produces characteristic community structures” PANTANAL - 66,100 square miles (171,100 square kilometers) -- Flood pulse – powerful dynamics distinguishes floodplains Hydrology – amplitude, frequency, predictability and source of from other wetlands flooding (10-15 m) Flood pulse concept – considers river, itscatchment area hydroperiod: large rivers’ floodplains : unimodal flood pulse and the floodplain and large amplitude (they all are connected by exchange of water, sediment, small creeks and rivers: unpredictable polymodal flood pulse organisms, biomass and energy) Sediment input– floodplains can be characterized by the Aquatic/Terrestrial/Transition Zone (ATTZ) amounts of dissolved and suspended substances introduced by floods (white x black waters) 4 Flooding - oxygen depletion Story from Pantanal: Paraguay river 6 weeks anoxic; fish kills; Spectrum of biota - from completely aquatic to completely often following extra dry season terrestrial (adaptations!!!) High DOC, CO2, low O2; Permanent water channels and/or lakes serve as important refuges (upland for terrestrial) oxygen depletion by microbial oxidation of CH4 (needs 8 moles of O2 for 5 moles of CH4) Internal nutrient and energy cycle - the exchange of nutrients and energy is the main reason for high productivity Species diversity - ~ 400 herbaceous species (both terrestrial and aquatic); trees; large fish diversity (the Amazon floodplain) Current status of Pantanal FISH MIGRATIONS cattle ranching is not too intense, but causes some degree of habitat modification. As the waters recede at the end of the dry season, many fish the majority of the Pantanal is in close to species migrate hundreds of pristine condition with most of its biota still kilometers upstream, and then extant reproduce during the early wet only two dirt roads cross the area season. less than 3 % of the Pantanal is currently Adult and young fishes enter included in protected area, the remainder of the flooded areas during the wet the land is privately owned BUT !!! season before returning to permanent rivers as the waters pesticide runoff from agricultural lands within recede. Migration upstream is the 500,000 km2 watershed of the Rio Paraguay (DDT, Parathion, Agent Orange) called piracema, migration back is called lufada. gold mining (over 700 gold-mining dredges operating along the Cuiabá River alone) the mercury used to separate out gold is now found at high levels in many fish populations Papyrus “swamps” (Cyperus papyrus) East, Central and South Africa Cyperus papyrus; C4 5 Sudd - ecosystem of southern Sudan on the banks of the Nile River - 150,000 sq. km - Jonglei canal (to bypass the Sudd) – impact on climate - habitat loss- Nile lechwe (good swimmers and waders) Okavango delta – inland delta Heterogeneity in flodplain vegetation determined by variations in soil chemistry and topography – mound building termites Island formation Diversity of fauna 6 Saddle-billed stork Dry season OKAVANGO – status West Siberia - extensive floodplains that we know close - Botswana, Angola & Namibia to nothing about !! partnership (OKACOM) -plans for the pipeline to Namibia - water diversion would threaten people living on the fringes of the floodplain - the world’s largest Ramsar site MESOPOTAMIAN WETLANDS 1970’s 2000 7 Loyality to the Leader Canal Main Outfall Drain (MOD) Glory River Euphrates floodplain Remaining wetlands 8 Remaining wetlands Drained areas Hamar - Newly flooded area RECENTLY FLOODED AREAS 1. Dam openings by local people 2. Damage of dams during military actions 3. Dam openings to slow down movement of British troops 4. Intentional flooding through the program of wetland restoration 5. Restored water flow from Iran 9 2003 Construct an environmental, social and economic baseline of the remaining and former marshlands Assist the marsh dwellers, who require economic opportunities and viable social institutions Improve the management of existing and newly reflooded marshlands and explore options to expand the restoration activities through pilot project interventions Develop and reach a broad internal and international consensus on a long-term comprehensive restoration strategy U.S. Agency for International Development (US AID) Development Altentatives, Inc. Problems with restoration: Lack of water High salinity Change of agricultural practives Settlement of drained areas 10 MARSH ARABS, MARSH DWELLERS Evidence of this isolated society appears on 5,000 year old Sumerian clay tablets For much of the historical period, the marshes themselves were long-established areas of refuge for rebels to the prevailing government, as well as by people living on small islands or in the settlements on the periphery. As recently as the 1970s, there was a limited government presence in the marshlands. The Iran-Iraq War of the 1980s brought the Saddam Hussein regime in full military strength, and the displacement of tribes closest to the border began. The marsh dwellers were said to have strongly supported the Iraq government during the war. 11 12 13 14.