The launching of craft from formal/constructed access points is likely to have minimal impact on marine features except where it involves trampling and scouring of the feature.

The launching of craft from informal non-constructed access points may result in compaction and erosion of features both on the land and in the intertidal area.

Swing moorings have minimal impact on marine features, except where anchors drag and disturb sediment and benthic communities, or where craft maintenance takes place on water or on mud/sand flats at low tide. These effects can be amplified in those few areas which experience a large increase in swing mooring provision.

Existing marina berthing has no impact on marine features, although new infrastructure development and maintenance activities do have an impact, particularly where it involves land claim and significant dredging (see chapter 5).

There is little evidence to suggest that marine engine emissions have a significant impact on marine features.

Noise disturbance is largely an amenity issue, although it may impact upon seals and dolphins. However, identification of the cause of disturbance is difficult as it can be caused by a number of contributory factors. These include the noise of the craft and its occupants, the proximity to the seals, the visual effect of the activity and the availability of a good means of escape.

Antifouling paint may be a significant localised source of heavy metal in the marine sediment, but its effects have not been quantified, particularly in the context of other sources of heavy metals such as industry, commercial shipping and agriculture.

Impacts from antifouling paints may be observable where present in high concentrations, particularly in low flushing estuaries and inlets and bays. Such concentrations are most likely to result from maintenance activities in marinas and boatyards or owner-maintenance activities on mud banks and sand flats.

Sewage discharge from craft can have localised impact on marine features, particularly in low flushing estuaries and inlets and bays, where it may contribute to reduced oxygen availability. However, its impact in fast flushing areas is negligible.

Although most litter in the marine environment is from sources other than water-based recreation, irresponsible behaviour from some boat users may contribute to the problem.

Disturbance to wildlife caused by motorboats will vary depending upon the type of activity, the time it takes place and the vulnerability of the wildlife.

Disturbance is observable at feeding, mating and roosting times but is extremely difficult to quantify and should be examined on a case by case basis. Vulnerable periods for some wildlife coincides with the low season for boating.

Boat wash may cause localised erosion of marine features but its impact is generally minimal in the context of natural effects.

Turbidity caused by boat movement is only observable in shallow, low flushing marine areas. It may have some localised impact on marine features, but many of these areas are avoided by motor boat users because of propeller fouling.

Blank Square- not applicable

m - minimal

w - observable, likely to be location specific

w * - observable at certain times, minimal at other times

l - appreciable

• physical impact on feature

• anchor drag and maintenance activities carried out at low tide

• this refers specifically to the impact of maintenance activities, such as hull scraping on mud banks at low tide

• impact of craft berthed at existing marinas, but not including new developments which are dealt with below

• only used on larger craft

• toilets only fitted on larger craft

• presence of craft in proximity to wildlife

• dependent on depth of water and speed of craft

• ingestion of heavy metals

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