하구및 연안생태Coastal management 2015 년 가을학기

Generalized Estuary; top view River, barrier island Environmental factor change; depth, physical energy level, water clarity, salinity, biota chemical concentration, oxidizing reducing conditions in sediments Sandy beach; little (visible) life; Wave; provides oxygen and food, remove wastes Oxidized Tidal pass; reduced currents, reducing condition Worm flat, mollusc beds; intertidal, subtidal with currents; filter feeders

Generalized Estuary; top view Submerged marine meadows, seagrass; light available. Fine sediments, trap sediments; reduced sediments Thalassia testudinum Zostera Marina Polyhaline: 30-35 ppt Mesohaline: 15 ppt Oligohaline: 0-5 ppt

Generalized Estuary; top view Intertidal wetlands Salt marshes: 온대 Mangrove swamps: 열대 Turbid waters Highly reducing Very fine sediments High growth rates Deposit feeders

Generalized Estuary; cross section view Vertical attributes: intertidal zone Flooded and exposed Salt marsh, mangrove wetlands, algal beds, sand or mud flat, reef or mud flat Light gradient Euphotic zone; photosyntheis Aphotic zone Oxidizing condition Aerobic or oxic Anaerobic or anoix ; reduced Coarse sediments; high energy, oxidized Fine sediments; calm water, reduced Influenced by biota; burrow, rooted plants

Generalized Estuary; longitudinal sections Fresh and sea water mixing Gradual increase of salinity Salinity increase with depth Net outflow to the sea at the surface Net inflow of salt water on the bottom. Euphotic zone depth decrease toward fresh water Most turbid water 1~5 ppt.; turbidity maximum phytoplankton, zooplankton, fishes Benthic animals; infauna, meiofauna Diversity of benthic animal changes along the logitudinal transects

Typical Estuarine food web Food chain, food web; E.P. Odum(1971) Trophic dynamics of estuary; complex Different primary producers; salt marsh plants, mangroves, submerged sea grasses, benthic algae Not a “grazing food web”(consumed alive); detritus food web Importance of bottom Plants grow on the bottom Flow of food and inorganic nutrients between water and bottom Filter feeders and deposit feeders Fish and birds ; bottom feeders Variety of PP, grazing+detritus, bottom, complex, many generalist top feeders  

Estuarine Energy flow Important processes go on which are not visible !!! If we want to know how estuaries work! Sunlight interact with N during photosynthesis P flowing out of sediment and being moved to surface Organic detritus flowing out of a marsh Energy flow diagram Detrital grazing food web Tidal currents; transporting detritus, moving phytoplankton to benthic animals Input of nutrients and organic matter; river and recycling Sunlight and inorganic nutrients;  

Estuarine habitat type High diversity of habitat type High diversity of physical habitats Beaches, passes, intertidal, shallow subtidal Deeper areas, deltas Biota has fully exploited these different areas Salt marsh, tide pool, algal flats, oyster Also creates diverse habitat

Ecological characterization and classification Physical environments Degree of protection from oceanic forces Freshwater input; dissolved + suspended materials Water circulation patterns; river + tidal currents + geomorphology ; tide is most important Depth; strong coupling between bottom and water column in shallow depth Salinity gradient; sharpness and pattern Rate of geomorphological changes Degree of change rather than the absolute level is more important !! Microclimates Water movements Chemical cycling Physical structure

Functional classification of estuarine ecosystems Odum and Copeland (1972); functional system based on an energetic analysis. Status of ecosystem is a balance between “ordering energy” and “stresses” Energy source Mechanical energy of moving water; food, recycling. Saves energy for organisms Sunlight; photosynthesis, thermal gradients Organic and inorganic fuel Stress energies; disordering energy Energy diverted from system; dam-reduce the material inputs Microscale random disordering; 2nd law of thermodynamics; problem for all living creature; high is estuary due to environmental variability Forced losses within system; potential energy is lost before it is used; tide, fishing by human, wetland distruction.

Functional classification of estuarine ecosystems Energy and adaptation in different ecosystems Estuarine ecosystem: Moderate stress energy and similar among different system So, changing temperature and sun light regime with lattitude is important Tropic : highest solar energy, thermal disordering to overcome Artic: prominent seasonal change, seasonal programing When stress energies become large, adaptation is similar (위도에 상관없이) : sedimimentary deltas, hypersaline lagoons, beaches

estuarine ecosystem in geological context 10,000~15,000 yr old.; since LGM Cease to exist in the near geological future!! Will fill up Sea level change; number decrease when sea level is low Species and types of biological communities are old. They will move back and forth

High productivity ; classical view 하구 생산성이 높다는 의미는? 2가지 의미 하구에 서식하는 생물의 생산성이 높음 자체 생산하는 유기물이 소비량보다 크다  고차 소비자 (예를 들면 어류) 에게 전달될 잉여 유기물이 있다. Three types of PP ; diverse OM source; organic debris Tidal movement Abundant nutrient supply; in situ or from river Rapid regeneration and conservation of nutrients Benthic regeneration + shallow well mixed water column Georgia estuaries: among the most productive natural ecosystem; Schelske and Odum (1962)

High productivity ; classical view; is it true? Georgia : salt marsh grass, phytoplankton, benthic algae Other estuaries : submerged seagrass magrove swamps, macroalgae Organic matter input from river. Year round production (?); only in low latitude. The role of detritus : chapter 7 Tidal action: most important Tidal action +other physical energy(wind, wave, riverine current) Produce very complex water movement Supply of nutrient : within the system or from the river? Rapid regeneration + conservation of nutrients; high coupling between water column and bottom.

Other hypotheses about estuary Intertidal wetland; produce OM for estuary Nursery for the estuarine species Many important reaction takes places; regulates estuarien chemistry Organic detritus is exported from wetlands and serves a food for estuarine consumers Supports rich fisheries; relationships between wetland and fisheries “ estuary-fish coupling”