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Seagrasses
continued
and production directly linked to the important
roles they play in coastal and estuarine
ecosystems. Recent studies have established
the importance of New Zealand estuarine
seagrass habitat to benthic macrofauna
communities (e.g. Turner et al. 1999, van
Houte-Howes et al., under review) as well
as recreationally and commercially important
fish species (e.g. Morrison and Francis
2001).
Criteria applied:
Species diversity; species richness; dependency
for other species; trophic/functional
diversity; conservation status/threat classification
both nationally and globally; cultural
values; degree of disturbance; special conditions
and specialised organisms; habitat complexity/diversity.
Status and management:
Seagrasses are vulnerable to human impacts
such as changes in sedimentation, coastal
modification, increased nutrients, and
direct physical disturbance. The 1994 New
Zealand Coastal Policy Statement identifies
the protection of areas of significant
indigenous vegetation as a national priority
for the preservation of natural character of
the coastal environment. Limited areas of
seagrass currently receive some level of
protection (e.g. Whanganui (Westhaven)
Inlet and Te Angiangi marine reserves
include areas of seagrass).
State of information:
Information on seagrass in New Zealand is
relatively limited – in particular for permanently
submerged beds. There is some information
on the physiology and ecology of
seagrass and some information on associated
biological communities.
References and further reading:
Grace and Grace (1976), Inglis (2003), Les
et al. (2002), Morrison and Francis (2001),
Ramage and Schiel (1998, 1999), Turner
et al. (1999), Turner and Schwarz (under
review), van Houte-Howes (under review),
Woods and Schiel (1997).
Photic zone rock wall
suspension feeding
assemblages
Not mapped during
the workshop
Location: Rock wall
assemblages are widespread
in northeast New Zealand,
offshore islands, and Fiordland.
Other examples along the rest
of New Zealand’s coastline
include rock stacks, pinnacles,
and similar formations.
Approximate area: Not
recorded during the workshop
Description of habitat type:
The photic zone, or the depth to which light
penetrates, is up to 200m. Rock walls have a
vertical relief or a very high gradient. They
are typified by strong to moderate currents.
Biological attributes:
Rock walls are home to many iconic taxa
including black corals, red coral, and
brachiopods. They have a high biomass
and surface cover of benthic species and a
high biomass of planktivorous fishes. Such
biomass is sustained by energy transfer
from the surrounding ocean ecosystem.
The habitat is characterised by very high
feeding upon pelagic energy sources – by
benthic/demersal species such as sponges,
tunicates and/or bryozoans, brachiopods,
hydroids, soft and hard corals, and a variety
of planktivorous fishes. The environment
is also a carbonate sediment “factory” for
surrounding soft bottoms (Nelson et al.
1988).
Non-geniculate coralline algae are
particularly important as they cover very
large areas of rock walls and are implicated
in invertebrate settlement and recruitment.
Criteria applied:
Species diversity; species richness; endemism;
dependency for other species; trophic/
functional diversity; representation (i.e.
across physical types)
Status and management:
Most species are not exploited or directly
threatened. Rock walls have high human
appeal (e.g. for scuba divers). Populations
are protected in New Zealand’s marine
reserves.
State of information:
Some rock wall sites are very well known,
especially in northeast New Zealand and
Fiordland. Other sites are only locally
known. They are best known within SCUBA
range, but other deeper rock walls are known
to occur.
References and further reading:
Battershill and Stocker (1993), Grange
(1986).
Black Coral
BIODIVERSITY – NEW ZEALAND’S MARINE ECOREGION ■ 67
©2004 DOC, Te Papa Atawhai