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Matthew Service

Matthew Service. Anthropogenic Pressures. Principal Pressures. Physical disturbance from direct impacts and resulting from morphological changes Contaminants; Heavy metals and Organic Nutrients. 1. Introduction. Residual near surface circulation. Potential energy anomaly (J m 3 )

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Matthew Service

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  1. Matthew Service • Anthropogenic Pressures

  2. Principal Pressures • Physical disturbance from direct impacts and resulting from morphological changes • Contaminants; Heavy metals and Organic • Nutrients

  3. 1. Introduction Residual near surface circulation Potential energy anomaly (J m3) and drifter tracks

  4. Time line • 1857 Dickie reports presence of M modiolus in Lough: • oysters in “central area” • cf 1900 Oyster fishery declines: • cf 1930 Spartina introduced; • Boyd (1969) describes plankton and water quality; • Jenkinson(1974) Describes hydrodynamics • 1970 first reports of Queen Scallop trawling: • Erwin 1977 Describes S Lough Benthos

  5. Roberts 1975 Describes M modiolus/Chlamys varia community; • 1978 Spartina spraying started; • 1979 Parker report on shellfish contaminants forerunner of Musselwatch study; • 1984 Investigation in double shelling and links with TBT; • 1984 Spartina spraying implicated as cause of sediment release; • Late 1980’s Queen Scallop trawling expands;

  6. 1985 Ardmillan Bay designated under EC Shellfish Waters Directive; • 1989 Brown publishes report claiming trawling is destroying M modiolus communities; • 1990 DOE(NI) Commission Mathematical Model • 1990 ISD report confirms trawling having impact; • 1993 DANI(DARD) introduces fishing restrictions; • 1993 DARD report on sediment metals • 1995 Possible introduction of Sargassum • 1996 Magorrian Thesis on Effects of commercial trawling (DARD studentship);

  7. 1997 Spartina spraying resumed; • 1997 DARD project on Recovery of benthic communities project initiated • DARD/EHS report on Trophic Status of Lough • 1998-2000 Further DARD Report on Sediment Contaminants • 1999 Sea defence reconstruction begun at Newtownards; • 2001 Release of sediment from Killyleagh foreshore;

  8. Eutrophication • Trace Contaminants (Heavy metals and organics) in sediments; • Shellfish contaminants; • Physical disturbance; • Algal toxins:

  9. Routine Monitoring • EC Shellfish Waters Directive • EC Shellfish Hygiene Directive • National Marine Monitoring Plan (OSPAR JAMP) • EHS Estuarine Classification

  10. Water Quality: • DARD/QUB AESD conducted a spatial and temporal survey of nutrient loading to the lough and nutrients, phytoplankton and chlorophyll in the lough over the period 1993-1996. • EHS estuarine class programme collects limited low frequency nutrient and plankton data.EHS also monitor heavy metals in water as part of the EC Shellfish Waters monitoring . • DARD- AESD analyse samples from active shellfish sites for presence of toxic algae fortnightly. This is reported annually. • EHS-EP report input data from Ballyrickard STW, Killyleagh STW and Downpatrick STW.- the Quoile.

  11. OSPARCOM Loading Data Loads(KG) 2500 2000 1500 Loads(KG) 1000 500 0 PCB 28 PCB 118 PCB 153 GAMMA- CADMIUM MERCURY ZINC TOTAL

  12. Nutrient Drivers: • EC UWWT Directive • EC Nitrates Directive

  13. Eutrophication is defined by the EC (in the Urban Waste Water Treatment Directive) as: • the enrichment of waters by nutrients, especially compounds of nitrogen and/orphosphorus, causing an accelerated growth of algae and higher forms of plant life to produce an undesirable disturbance to the balance of organisms present in the water and to the quality of the water concerned

  14. Taylor and Service (1998)concluded • Irish Sea is the largest source of nitrogen, phosphate and silicate loading to Strangford Lough • The total annual anthropogenic load of DIN and SRP (excluding the Irish Sea and airborne deposition) to the Lough are 1 201 and 116 tonnes, respectively;

  15. Eutrophication is defined by the EC (in the Urban Waste Water Treatment Directive) as: • the enrichment of waters by nutrients, especially compounds of nitrogen and/orphosphorus, causing an accelerated growth of algae and higher forms of plant life to produce an undesirable disturbance to the balance of organisms present in the water and to the quality of the water concerned

  16. Heavy Metals • Killyleagh outfall generated more than 10 tonnes of chromium per annum, although during the early 1990s, declined to nearer 1 tonne per annum; • The high mercury concentration in mussels from Whiterock were similar to those found in mussels from the Inner Forth estuary in Scotland (Davies and Pirie 1980 in Gault et al. 1983) ; • TBT Implicated in double shelling in oysters;

  17. TBT • Routine monitoring for Imposex and Intersex in Dogwhelks and Winkles by EHS has shown little sign on effect; • Edwards (2002) Suggested that Imposex records in Whelks show a reduction in TBT levels.

  18. Sediment Quality • In 1990 approximately 30 samples were analysed at the <63um particle size level using an aqua regia digest • In 1996 a smaller numbers of stations were sampled and analysed for heavy metals at the <2mm particle size level using an HF digest for geochemical normalisation. • Hydrocarbons (PAH’s) a spatial survey was carried out in 2000 at again about 12 sites. • DARD have one NMMP sediment station in the Lough that is sampled for heavy metals, pesticides, PAH’s. • EHS –EP have sediment sampling sites(4?) in the lough as part of their Estuarine Classification Monitoring

  19. Service (1993) concluded that with the exception of chromium and mercury, all other metals show strong co-correlation and are therefore from a common, geochemical weathering source. By contrast, chromium and mercury are most likely to originate from the point source outfall at Killyleagh.

  20. 2. Trace metal contamination

  21. Sediment Metals 2000 180 Irish Sea Sites 160 AL 140 Cu 120 PB 100 NI 80 B Zn 60 AS 40 CR 20 0 NMP4 nmp5 38a NMp3 s lough

  22. Heavy Metals in Modiolus modiolus 35.00 30.00 *10 25.00 20.00 Donaghadee *10 S Lough 15.00 10.00 5.00 0.00 Ag Cd Cr Cu Fe Hg Ni Pb Zn As

  23. Physical disturbance due to: • Trawling or dredging; • Sediment relocation: • Release of sediment or changes in coastal cell • change in prevailing wind

  24. Otter Boards or trawls hold the net open and may impact the sea bed Tickler chains banned in Strangford Lough Sediment plumes may help “herd” fish

  25. The worst damage caused by otter boards • The area between scars showed no textural differences • area effects has a characteristic texture

  26. Side-scan sonar survey area

  27. Strangford is subject to variety of pressures • arising both from the catchment and directly • there is no evidence that the Lough is eutrophic or heavily contaminated • trawling can impact seabed communities

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