3.3.1 Potential impacts during construction
3.3.1.1 Physical disturbance 23.
There is potential for direct physical disturbance of the sea bed during construction from the installation of cables foundations (through placement of jack up barge legs, spud cans and anchors/chains) and sea bed preparation (dredging). These construction phase activities have the potential to impact fish and shellfish species including species for which spawning or nursery grounds have been defined as well as those with designated conservation status. Disturbance at any particular time during the construction period will be of limited extent and duration.
3.3.1.1.1 Proposed method for assessment
The area of impact from physical disturbance and proportion of the population affected will be assessed using a worst case scenario for the construction activities identified.
Sensitivities will be informed by available literature including the assessments available on MarLIN. Assessments of sensitive species and species with conservation status are guided by review of available literature including Strategic Environmental Assessments (SEAs) (including Rogers and Stocks, 2001).
Assessments to spawning and nursery grounds are guided by the known spawning and nursery habitats mapped by Coull et al, (1998) and updated by Ellis et al, (2012).
Magnitude will be assessed based on the information presented in Chapter 7 Marine Geology, Oceanography and Physical Processes, Chapter 8 Marine Water and Sediment Quality and Chapter 10 Benthic Ecology. The level of impact will be quantified by calculating the maximum area of disturbance as a percentage of the total available habitat, spawning or nursery area within East Anglia THREE and EAST Anglia FOUR according to the worst case scenario.
3.3.1.2 Increased suspended sediments and sediment redeposition 24.
Construction activities have the potential to cause mobilisation of sediments in the water column and an increase in suspended sediment concentrations (SSC). Sensitive species may react to this through physical or reproductive decline or it may impact upon migration or spawning behaviour.
3.3.1.2.1 Proposed method for assessment
The magnitude of the potential impact will be based upon the outcomes of Chapter 7 Marine Geology, Oceanography and Physical Processes and Chapter 8 Marine Water and Sediment Quality. The magnitude of the effect of sediment smothering on fish and shellfish receptors will be considered in terms
Evidence plan Fish and Shellfish Method Statement
East Anglia THREE and East Anglia FOUR Offshore Windfarms
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