CHAPTER 6 . Coastal Environmental Management in Southeast Australia: The Roles of Ecology 109
capricorni were measured in those estuaries in which they were found. Assemblages
were examined in a number of estuaries around Sydney, although all assemblages were
not examined in each estuary because of their patchy distributions.
The experimental design was to compare replicate sites in each of a number of marinas, areas with mooring-buoys and control locations (similar habitats without permanent mooring facilities) in different estuaries, although the precise detail of the design
differed for the different assemblages according to the precise hypotheses being tested.
There were no widespread and general effects of either marinas or other boat moorings on the faunal assemblages or seagrasses, although effects could be identified for
some assemblages in some places. For example, the animals in the sediments in one
marina in Pittwater (one local estuary) were consistently different from those in the
relevant boat-mooring sites and control sites. The sediment itself was much finer near
this m~rina and sediment-size is known to be a strong determinant of the infaunal
assemblage (Gray 1974). Whether the previous construction or the running of the marina themselves influenced the sediment -size is not known and was outside the scope
of the study. This difference was, however, specific to this marina and not found near
other marinas. It cannot therefore be identified as an effect of marinas in general.
Similarly, there were significant differences in the infauna between marinas, boatmooring areas and their control locations at some times of sampling, but not at others
because of variable temporal changes in the fauna. Managerial decisions based on single samples in time, no matter how well replicated in space, are likely to be faulty because they do not take into account natural temporal change.
In other examples, marinas did appear to have had persistent localized effects on
the fauna, although different species responded to marinas in different ways. For example, in Pittwater, paraonid polychaetes and Anthurids in sediments were consistently
negatively affected by marinas, maldanid polychaetes were positively affected by marinas and none was affected by other boat-mooring facilities. In Port Jackson, abundances of cirratulid polychaetes and general diversity were negatively affected by marinas. Therefore, effects of marinas on the same faunal assemblage varied from marina to marina and from estuary to estuary.
It was quite clear that once a marina or boat-mooring area was established, the areal
extent of surrounding sel).grasses and the encrusting animals and plants on the blades of
seagrasses were not affected by the continued operation of marinas or boat-mooring
areas. This contrasts with suggestions from other studies that seagrasses will be adversely affected by runoff containing metals in urban environments (Ward 1989). Similarly, the animals associated with the leafy portion (the blades) of the kelp Ecklonia
radiata did not show any strong or consistent impact around boat mooring areas or
marinas, again contrasting with studies elsewhere (Jones 1973). In contrast, in Port
Jackson, the animals living in the holdfasts of the kelp showed consistent and significant impacts of marinas and boat-mooring areas, with fewer Nematodes, Tanaids,
Ostracods, Isopods and Gammarideans than in control locations. These comparisons may,
however, be confounded by the locations of the marinas, boat-mooring areas and control
locations in Port Jackson. The control locations were necessarily closer to the open ocean
because of the difficulty of finding locations without mooring facilities near the marinas.
This study convincingly demonstrated that any effects of marinas or other boatmooring facilities on the associated invertebrate assemblages were varied in space and
time, making any environmental assessment baseq on single times of sampling diffi-
capricorni were measured in those estuaries in which they were found. Assemblages
were examined in a number of estuaries around Sydney, although all assemblages were
not examined in each estuary because of their patchy distributions.
The experimental design was to compare replicate sites in each of a number of marinas, areas with mooring-buoys and control locations (similar habitats without permanent mooring facilities) in different estuaries, although the precise detail of the design
differed for the different assemblages according to the precise hypotheses being tested.
There were no widespread and general effects of either marinas or other boat moorings on the faunal assemblages or seagrasses, although effects could be identified for
some assemblages in some places. For example, the animals in the sediments in one
marina in Pittwater (one local estuary) were consistently different from those in the
relevant boat-mooring sites and control sites. The sediment itself was much finer near
this m~rina and sediment-size is known to be a strong determinant of the infaunal
assemblage (Gray 1974). Whether the previous construction or the running of the marina themselves influenced the sediment -size is not known and was outside the scope
of the study. This difference was, however, specific to this marina and not found near
other marinas. It cannot therefore be identified as an effect of marinas in general.
Similarly, there were significant differences in the infauna between marinas, boatmooring areas and their control locations at some times of sampling, but not at others
because of variable temporal changes in the fauna. Managerial decisions based on single samples in time, no matter how well replicated in space, are likely to be faulty because they do not take into account natural temporal change.
In other examples, marinas did appear to have had persistent localized effects on
the fauna, although different species responded to marinas in different ways. For example, in Pittwater, paraonid polychaetes and Anthurids in sediments were consistently
negatively affected by marinas, maldanid polychaetes were positively affected by marinas and none was affected by other boat-mooring facilities. In Port Jackson, abundances of cirratulid polychaetes and general diversity were negatively affected by marinas. Therefore, effects of marinas on the same faunal assemblage varied from marina to marina and from estuary to estuary.
It was quite clear that once a marina or boat-mooring area was established, the areal
extent of surrounding sel).grasses and the encrusting animals and plants on the blades of
seagrasses were not affected by the continued operation of marinas or boat-mooring
areas. This contrasts with suggestions from other studies that seagrasses will be adversely affected by runoff containing metals in urban environments (Ward 1989). Similarly, the animals associated with the leafy portion (the blades) of the kelp Ecklonia
radiata did not show any strong or consistent impact around boat mooring areas or
marinas, again contrasting with studies elsewhere (Jones 1973). In contrast, in Port
Jackson, the animals living in the holdfasts of the kelp showed consistent and significant impacts of marinas and boat-mooring areas, with fewer Nematodes, Tanaids,
Ostracods, Isopods and Gammarideans than in control locations. These comparisons may,
however, be confounded by the locations of the marinas, boat-mooring areas and control
locations in Port Jackson. The control locations were necessarily closer to the open ocean
because of the difficulty of finding locations without mooring facilities near the marinas.
This study convincingly demonstrated that any effects of marinas or other boatmooring facilities on the associated invertebrate assemblages were varied in space and
time, making any environmental assessment baseq on single times of sampling diffi-