Estuaries, Sediments and Dredging Professor Mike Elliott Mike.Elliott@hull.ac.uk Institute of Estuarine & Coastal Studies, University of Hull http://www.hull.ac.uk/iecs
Antony et al., 2009, Ecol. & Society
Regions of an estuary (e.g. Forth Estuary, Scotland) Tidal limit Tidal Freshwater Area (TFA) Head of Estuary Freshwater Seawater Interface (FSI) Middle Estuary Firth of Upper estuary Estuary Mouth Forth Lower Turbidity Estuary Estuary Maximum Zone limit
The upper estuarine areas – TFA, FSI and TMZ
global position tectonics Coriolis climate physiography underlying tidal regime geology temperature geomorphology regime wind regime gas, hydro- mineral wave regime thermal seeps inputs water run-off pH, salinity regime hydrological regime water current chemosynthesis strength water mixing water input sediment supply density regime salinity regime erosion-deposition depth substratum cycles regime stratification residence time exposure turbidity regime regime pH regime O 2 regime light regime nutrient regime Substratum colour regime fundamental Water-column photic zone niche fundamental niche
Hydroclimagraphs - for the Upper Forth Estuary
Sedimentary inter- relationships (from Elliott et al 1998 (UK Marine SAC Project on www.englishnature.gov.uk) e.g. fine cohesive and poorly- sorted sediments in low energy areas, small average particle size, created under low flow conditions, giving high amounts of silt & clay and organic matter (and often contaminants), poor oxygen and so anoxic conditions.
Sedimentary inter- relationships Between current speed, particle size, erosion, transport and deposition. (Stowe, 1996)
Healthy estuarine mud – main message ‘ look after the hydrography and the sediments, then the invertebrates and their predators will then be OK’
Marine/Estuarine Community – Forcing Variables Fundamental niche Physico- chemical attributes env.-biol. links biol.-env. links Community functional attributes Community biol.-biol. links structural attributes
(From Reise (1991) in Elliott & Ducrotoy (1991)) Benthos 3-D structure and functional groupings
Bird and fish food!
‘Normal’ seabed organisms - many species, all sizes Polluted seabed community - few species, small organisms
Seabed community types and species richness along estuary-marine continuum (Elliott & Kingston 1987)
Organisms modifying sediments
Estuaries as a major overwinter feeding areas for wading birds and feeding and refuge areas for fishes
Erosion-Deposition Cycles in Estuaries • 6-hourly – stronger currents on ebb and flood tide leading to erosion, weaker currents at high and low slack water leading to deposition • Daily – diurnal tides (2 tidal cycles per day but not equal strength) • Fortnightly – spring tide one week (stronger tides, more water and greater currents, hence more erosion); neap tide other week (weaker tide, lower currents, more deposition • Lunar – 2 spring and 2 neap but not equal strength • Euinoctial – 6 monthly intervals, different tidal regime, hence different strength • Winter high flows down estuary pushing sediments seawards and then tidal-dominated in low river conditions, allowing sediment pulsing back up the estuary • Random events – storm surges, spates, pluvial and fluvial flooding
Spatial and temporal changes to sediments (Elliott et al . 1998; 2001) Spatial extent of intertidal Small Large Low bioturbation foraging / micro disturbance by wader foot prints and beak activity Intensity of disturbance on intertidal flats bait digging - manual continuous wave and shore processes beach nourishment - trickle charging bait digging - mechanical beach nourishment - dumping methods and mechanical placement pipeline construction extreme wave and tidal events High
(a) Natural and (b) anthropogenic accreting (depositing) areas (a)Natural bay (Inverkeithing Bay, Forth) (b)Burntisland Docks, Firth of Forth
Immingham (plus Hull, Goole, Grimsby) – Largest Ports Complex in UK
Dredging and dredged-material disposal
Humber Estuary - major trading route & ports (need dredging)
Trailing suction hopper dredger
Port bell-mouth dredging and disposal
Unhealthy systems? Medical ( ) – Environmental – *1 • Diagnosis • Assessment (*2) • Prognosis • Prediction • Treatment • Remediation/Creation/ Restoration • Recovery • Prevention Prevention (*1 Steevens et al 2001 - Human Ecol. Risk Ass.) (* 2 using extension of symptoms for the diagnosis of ecosystem pathology) Comparison of the health of medical and environmental systems (modified from Elliott & Cutts 2004; see Tett et al., MEPS 2013)
Challenges for science & management: There is only one big idea in estuarine and marine management: how to maintain and protect ecological structure and functioning while at the same time allowing the system to produce ecosystem services from which we derive societal benefits. • Recovery/coping with historical legacy • Endangered coastal and marine ecosystem functions • Legal & adminstrative framework • Economic prosperity and delivery of societal benefits • Coping with climate change & moving baselines
The Health & Integrity of the estuary: Environmental Quality Objectives 1. The protection of all of the existing defined uses of the estuary system; 2. The ability to support on the mud bottom the biota necessary for sustaining sea fisheries; 3. The ability to allow the passage of migratory fish at all stages of the tide. (Based on those proposed by Royal Commission on Environmental Pollution, 3 rd report 1972) (Define EQO, derive EQS, set consent conditions and discharge limits bearing in mind EU Directives, PARCOM, the 'precautionary principle and the Red list')
KEY Management of fisheries International International Inshore fisheries from 6nm to 200nm for Law / Bodies & management 0-6nm sustainable fisheries Commitments Conventions Safe consumption of shellfish and fish Integrated pollution control Marine environmental protection Flood and coastal erosion protection Control of waste ICES LONDON Transitional and coastal waters CONVENTION OSPAR, status Nitrates & & PROTOCOL HELCOM, fertiliser control UNEP-MAP, Coastal and marine waters status BUCHAREST U.N. FRAMEWORK (Regional Seas Treatment of urban CONVENTION ON CLIMATE Conventions) waste water CHANGE (UNFCCC) Environmental liability to prevent and remedy environmental damage UNCLOS U.N. Quality of bathing KYOTO CONVENTION on waters Integrated maritime policy PROTOCOL BIOLOGICAL IMO DIVERSITY Renewable energy BALLAST targets Marine spatial planning (MSP) & BERN BONN MARPOL WATER coastal zone management (CZM) CONVENTION CONVENTION CONVENTION Regulations to control shipping & pollution CITES RAMSAR from ships to give safer shipping, Biodiversity strategy CONVENTION navigation and pollution control and ESPOO operation CONVENTION UNESCO Protection of wild birds in transitional, coastal PROTECTION OF and marine waters UNDERWATER INTERNATIONAL Strategy and regulations on CULTURAL CONVENTION ON invasive alien species control Protection of habitats & species in transitional, HERITAGE SALVAGE coastal and marine waters Strategic assessment of public plans or CITES fauna & flora for projects in a transboundary effect (Boyes & endangered species protection Elliott MPB Impact assessment of a Protection of marine plan or project archaeology 2014)
Slufter/Papasbiek System for Contaminated Dredgings
Professor Mike Elliott, Institute of Estuarine & Coastal Studies, University of Hull Mike.Elliott@hull.ac.uk, http://www.hull.ac.uk/iecs
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