A guide to the deep-water sponges of - NMFS Scientific Publications ...

compounds have been isolated from sessile marine
invertebrates, algae, and microorganisms worldwide
(Faulkner, 2002). Many of the compounds are currently
in early clinical or late preclinical development for use
as treatments for cancer, tuberculosis, HIV, asthma, and
many other diseases and ailments (Newman and Cragg,
2004). Deep-water sponges show particular promise in
this emerging research area, and several species collected
from the Aleutian Islands as part of a pilot program
in 2004 exhibited near 100% inhibition during primary
screening for M. tuberculosis (Hamann 3 ). Only a handful
of sponge species from the Aleutian Islands have been
examined for the presence of secondary metabolites
(e.g., Na et al., 2010), but so far “hit rates” for biomedically
active compounds are on the order of 10%, rather
than 1% which is typical for samples collected elsewhere
(Hamann 3 ).
Ecology of sponges
Importance as fish habitat
Deep-water sponges provide important habitat to many
species of fish and invertebrates, mostly as a source of
refuge from predation and adverse conditions (e.g.,
strong currents) and as focal sites for foraging on prey
species that aggregate in sponge habitat. Some fish
use sponges (e.g., Aphrocallistes vastus and Acanthascus
dawsoni dawsoni) as spawning substrate (Busby 4 ) and
others likely use sponge habitat as breeding sites. In
Alaska, many commercial and non-commercial fisheries
species are associated with deep-water sponges. Most
associations are believed to be facultative rather than
obligatory. Sponges provide important refuge habitat
for juvenile rockfish (Sebastes spp.) in the Gulf of Alaska
(Freese and Wing, 2003) and juvenile golden king crabs
(Lithodes aequispina) in the central Aleutian Islands
(Stone, 2006). Sponges also contribute to the biodiversity
of deep-water habitats by providing spawning substrate
for many species that are important trophic links
to larger consumers (Fiore and Jutte, 2010).
Deep-water sponges are really no different than
deep-water corals in the degree to which they provide
structure; it depends on their maximum size, growth
form, abundance, intraspecific fine-scale distribution
(i.e., patch size and density), and interaction with
other structure-forming invertebrates. In general,
large arborescent species (e.g., Axinella blanca) and
3 Hamann, M. 2009. Personal commun. Unpubl. data. University
of Mississippi, P.O. Box 1848, University, MS 38677.
4 Busby, M. 2010. Personal commun. Alaska Fisheries Science
Center, NOAA, NMFS, 7600 Sand Point Way N.E., Seattle, WA
98115.
those with vase-like or barrel-like morphologies (e.g.,
Acanthascus dawsoni dawsoni and Mycale loveni) provide
much surface area and consequently refuge space.
Large sponges such as Mycale loveni have high value as
fish habitat due to their size (up to 1 m high and wide)
and abundance (up to 11 sponges per m 2 in the eastern
Gulf of Alaska). Adult sharpchin rockfish (Sebastes
zacentrus) and juvenile Sebastes spp. frequently use the
cone-shaped sponges as perches in the eastern Gulf
of Alaska. Smaller sponges at high densities may also
provide important habitat. For example, finger sponges
(Axinella rugosa) are small (maximum dimensions only
2 cm wide by 17 cm high), but are used as perches
by juvenile rockfish (Sebastes spp.) when present at
high densities (up to 63 individuals per m 2 ) in steep
bedrock habitats (Stone, unpubl. data, 2005). Species
such as Artemisina stipitata have several attributes that
make them important as fish habitat, including large
size, tendency to occur in dense patches (contagious
distribution), and interaction with other emergent
epifuana. Encrusting species such as Plakina tanaga,
P. atka, and Bubaris vermiculata have little value as fish
habitat. The degree to which sponges provide fish
habitat also depends greatly on their depth distribution
relative to that of shelter-seeking fishes. In the Aleutian
Islands, for example, sponges found at depths greater
than about 1200 m are less important as refuge habitat
because most of the fish species at those depths appear
to be less structure-oriented.
In general, calcareous sponges are not of sufficient
size or adequately abundant to provide important fish
habitat. Leucandra tuba may be important for juvenile
fish that use the easily accessible cavernous interior of
this species to escape from larger predators. In contrast,
demosponges are often quite large and form dense
“gardens” in some areas of the Aleutian Islands (Fig. 1).
Hexactinellid sponges are extremely important as fish
habitat. Their skeletons are persistent after death and
consequently provide the framework for the building
of reefs or bioherms. Intact skeletons, and to some degree
detached and fragmented skeletons, also provide
attachment substrate for other sedentary structureproviding
fauna, including hydrocorals, octocorals, and
demosponges (Stone, unpubl. data, 2004).
Vulnerability to disturbance
Bycatch observations in the Aleutian Islands and other
regions of Alaska clearly support our submersible observations,
indicating that sponges are far more abundant
than corals in deep-water habitats. Sponges, particularly
demosponges, appear to be the most abundant emergent
epifauna in the Aleutian Islands. Approximately
352 metric tons (t) of sponges are removed from the seafloor
by commercial fishing in the Aleutian Islands and
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