randomly selected sites used. As shown in Section 4.3.2, a further 36 benthic stations will be required in the unsurveyed areas to ensure a consistent survey effort of 0.13 stations per km2. It should be noted however, that by surveying only these outstanding 36 stations, temporal inconsistencies could affect the cable corridor assessment and it would be prudent to discuss this temporal issue and the need for future surveys with the regulator.
5.3 Epibenthic Surveys
As found for the benthic surveys, the epibenthic characterisation effort for East Anglia THREE and FOUR is sufficient to assess any impacts to the epibenthic ecology of that area. It should be noted that this analysis is in relation to benthic invertebrate taxa only and does not include fish species, for which there was dedicated survey effort.
Similarly, as discussed in Section 5.2, assuming that the homogeneity recorded within the surveyed sites also applies in the unsurveyed areas, the epibenthic cable corridor community surveys should demonstrate similar high Power/low EDPC levels. As shown in Section 4.4.2 a further 3 benthic stations will be required in the unsurveyed areas to ensure a consistent survey effort of 0.01 stations per km2. Due to the small number of sample stations that are required throughout the cable corridor as a whole however, (6 stations are required to achieve statistical Power and maintain consistency with the previously sampling density), APEM recommended surveying 6 stations throughout the entire cable corridor which will result in all epibenthic samples from the cable corridor being gathered within the same sample season.
5.4 Spatial v Temporal variation.
This report is tailored towards a short term, pre- and post-construction study to assess potential effects of development using analyses which compare the (pre- and post- impact) mean and variation of assemblage diversity metrics for each of the relevant areas. Nonetheless, the extremely high Power suggests that the survey effort will be suitable for a longer term monitoring program.
It is important to note however, that short term changes in climactic or physical oceanic conditions may provoke a change in ecology which could falsely be attributed to development (for example, following a severe storm event). APEM recommends therefore that consideration is given to the development of longer term monitoring, and if this is not possible due to cost or other considerations, monitoring of local marine conditions is undertaken to exclude the potential effect of other causal factors in the event of major change being discovered.
