al., 2011). Bathymetric barriers to dispersal are also apparent in the phylogenetic
community structure of deep-water octocoral assemblages in the Gulf of Mexico
(Quattrini et al., 2014).
Finally, the distribution of genetic polymorphism among populations of octocorallians
and antipatharians across seamounts of the Pacific spanning 1700 km also showed no
evidence for strong endemism, supporting the ability for large scale dispersal of the
species studied (Thoma et al., 2009). It is only recently that the embryonic and larval
biology of Lophelia pertusa has been described (Brooke and Järnegren, 2013). The
settlement and benthic juvenile stages have not been observed. Knowledge on the
possible effects of ocean acidification on coral reproduction so far comes from tropical
corals but it is reasonable to believe that there are many similarities (Albright, 2011).
Altogether, the present state of knowledge of genetic connectivity of deep-water corals
suggests that the potential exists for some species to disperse and colonize across large
distances in response to major environmental changes, and some species have a more
limited dispersal capacity. However, more studies need to be conducted at a finer
spatial scale using specific genetic markers (e.g. Dahl et al., 2012) to improve the
understanding of the impact of environmental changes on connectivity and persistence
at the local scale. These different degrees of differentiation among and within ocean
basins indicate the need for regional-scale conservation strategies.
4.
Implications for Services to Ecosystems and Humanity
Impacts on cold-water corals and the structures they form would have significant
implications for the functioning of the surrounding deep sea and wider oceanic
ecosystems. The linkages from shallow to deep water, and back again, implicate cold-
water corals as key components of the broader oceanic ecosystem. The physical
structures created by cold-water corals support fisheries through the direct provision of
habitat, refuge, or nursery grounds, which is likely to lead to increases in commercially
significant fish populations. These effects are most pronounced where cold-water corals
are known to be highly abundant, such as on the North Atlantic, North Pacific, and
Australian and New Zealand seamounts.
The ecosystem services provided go beyond the direct provision of substrate and shelter
(see review by Foley et al., 2010). The complex habitat formed by cold-water corals
increases the heterogeneity of the continental margin, promoting higher diversity
(Cordes et al., 2010). As in other ecosystems (e.g. Tilman et al., 1997), increased
diversity mostly promotes higher levels of ecosystem function, including carbon cycling.
This specific ecosystem service may be important in relatively oligotrophic regions such
as the Gulf of Mexico and the Mediterranean where cold-water corals-enhanced
nutrient cycling and remineralization would generate nutrients that may be transported
back to the surface. Recent findings from reefs off Norway demonstrated their
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significant role in carbon cycling, raising additional concerns as to the impact of their
disappearance on global biochemical cycles (White et al., 2012b).
Cold-water corals also hold genetic resources that may provide services to humanity,
either directly or through their function as biodiversity hotspots in the deep sea (Arrieta
et al., 2010). Taxa such as cnidarians, sponges, and molluscs have been shown to
harbour the highest abundance of natural marine products of interest for biotechnology
development (Molinski et al., 2009; Rocha et al., 2011). As an example, the anti-AIDS
drug AZT was developed from an extract of a sponge from a shallow Caribbean reef (de
la Calle, 2009). At least half, and likely far more, of the diversity of corals and sponges
lies in deep, cold waters (Cairns, 2007; Hogg et al., 2010), and therefore, these
understudied and often unknown species have the highest potential for new
discoveries. With this potential comes a management concern, especially as some of the
potential genetic resources (see also chapter 29) harboured within the genomes of cold-
water corals and sponges lie in areas beyond national jurisdiction (Bruckner, 2002; de la
Calle, 2009).
5.
Conservation Responses
Raised awareness of the susceptibility of cold-water coral communities to impacts of
human activities in recent decades has resulted in national
and international actions to
protect cold-water corals and facilitate recovery of coral areas adversely affected in the
past. In some areas where significant damage was documented, e.g. along the
continental shelf off Norway (Fossa et al., 2002) and on seamounts in Australia and New
Zealand (Koslow et al., 2001), national legislation was introduced and specific
management measures were implemented. A growing number of protected areas and
fisheries closures in areas within national jurisdiction in the Atlantic and North Pacific
have followed, and in some countries, e.g. Norway, it is illegal to deliberately fish in
coral areas even if the area is not formally closed as a protected area.
Since the mid-2000s a series of United Nations General Assembly (UNGA) resolutions
(e.g. 61/105, 64/72, 66/68) on sustainable fisheries have called for a number of
measures, including the implementation of the International Guidelines for the
Management of Deep-Sea Fisheries in the High Seas (FAO, 2009), and action to avoid
significant adverse impacts of fisheries on vulnerable marine ecosystems,
1
including e.g.
cold water corals.
2
These resolutions focus in particular on areas beyond national
1
The International Guidelines for the Management of Deep-Sea Fisheries in the High Seas describe
vulnerable marine ecosystems and list characteristics to be used as criteria in the identification of such
ecosystems.
2
The Annex to the Guidelines refers to “certain coldwater corals” as part of examples of species groups,
communities and habitat forming species that are documented or considered
sensitive and potentially
vulnerable to deep-sea fisheries in the high seas, and which may contribute to forming vulnerable marine
ecosystems.
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