Cold-water coral reefs

Christopher HinchcliffeAKVA

Photo from (1), pp. 7

Environmental Requirements 1

Sufficient food supply Any particulate/dissolved organic

matter Phytodetritus, zooplankton faeces,

zooplankton Dissolved inorganic carbon levels (DIC)

and seawater density DIC <2170 µmol/kg, ρ: 27.35 – 27.65

kg/m3 => High quality reef DIC >2170 µmol/kg, ρ: <27.35 /

>27.65 kg/m3 => Low quality reef Temperature: 4 – 14oC; (6 – 9oC) Salinity: 32 – 38.8; (~ 35) Oxygen: 3.8 – 7.2 ml/L; (6.0 – 6.2 ml/L) Photo from (1), pp. 13

Reproduction Asexual (cloning) 1

Fragmentation Responsible significant

proportion of reef building

Sexual reproduction 1

Separate sexes Broadcast spawners Spawning February –

March (in pipeline area)

Larval Drift Genetically distinct offshore and fjord

populations 2

Fjord populations more isolated (bottlenecked)

Strong local recruitment on the slope 2

Moderate gene flow recorded between slope sub-populations 2

Fjords much more highly differentiated Shelf Edge Current (Iberian Margin to

Norwegian Sea) capable of transporting larvae Larvae planktonic for 3 – 5 weeks

Larvae will settle on any hard substrate

Image from http://oceancurrents.rsmas.miami.edu/atlantic/img_mgsva/slope-YYY.gif

Trawling Grossly destructive

30 – 50% of Norwegian reefs impacted/destroyed 3

Continuous, wide-spread impact Areas trawled until no fish

left (i.e. no habitat (coral) left for fish to inhabit)

Direct impact of trawl gear Indirect impact of

suspended sediment Trawled sediments may drift

to protected areas

Top image from (3) ; bottom image from (4)

Oil Installations Coral first described on North

Sea oil installations in late 1990s 5

Numerous records since 6

Growth rates of 26 ± 5 mm yr -1 6

Only very localised effects of muds and cuttings.

Tolerant to weeks of low level elevated sediments 1

Larvae most susceptible Time activities outside

spawning/recruitment

Images from (6)

Restitution Fosså et al (2002)

suggest restitution to small colonies over 100s years, full reefs after 1000s. Possibly a little

conservative given recent growth estimates.

Tropical reefs from otherwise undisturbed areas show high resilience

Full community restitution likely to fall outside 10 year window

Image from (4)

References1. Järnegren, J. & Kutti, T. 2014. Lophelia pertusa in Norwegian waters. What

have we learned since 2008? – NINA Report 1028. 40 pp. 2. Le Goff-Vitry MC, Pybus OG, Rogers AD (2004) Genetic structure of the

deep-sea coral Lophelia pertusa in the northeast Atlantic revealed by microsatellites and internal transcribed spacer sequences. Molecular Ecology 13:537-549

3. Fosså JH, Mortensen PB, Furevik DM (2002) The deep-water coral Lophelia pertusa in Norwegian waters: distribution and fishery impacts. Hydrobiologia 471:1-12

4. Roberts JM, Wheeler AJ, Freiwald A (2006) Reefs of the deep: The biology and geology of cold-water coral ecosystems. Science 312:543-547

5. Bell, N. & J. Smith, 1999. Coral growing on North Sea oil rigs. Nature 402: 601.

6. Gass SE, Roberts JM (2006) The occurrence of the cold-water coral Lophelia pertusa (Scleractinia) on oil and gas platforms in the North Sea: Colony growth, recruitment and environmental controls on distribution. Marine Pollution Bulletin 52:549-559