When we think of coral reefs♣≈, clear, warm waters; g£ently swaying sea fans;±Ω brightly colored fiΩ§∑sh tend to spring to mind. The reef∏★®s we'll be exploring on this expedition live ©®≠>in a different habitat than shallow ree€λ×≈fs, but are very similar in many way÷β<s.
Deep-sea corals are defined as ↔©corals that live at depths greater than 5σ∏₹π0 meters, but most species live in the deep oc λean at depths of several hundred meter™®s, in cold, dark, rocky habitatsγ , often far from shore. Unlike shallow-wa✘↓₩ter reefs, which are limited to war ↕m tropical waters, deep-sea corals are found ∞ αthroughout the world's oceans™✘, from the tropics to the polar regionsφ ∏↔. Like shallow corals, deep-sea reefs are crea≥¥$ted by stony corals ™≈that have formed large geol'±ogical structures over thousa•®<nds of years.
While there are many species of corals ☆β that build reefs in shallow water, including hundβφreds of species, only 6 deep-sea ston∏↓"γy corals can create reefs. The most co↔€≥×mmon of these is "Lophelia pertusa," which forms huge coral reσ♥efs in the Atlantic Ocean, inclγσ∏uding the Gulf of Mexico and the South Atlantic♥↓ Gulf.
Shallow-water corals rely on p$hotosynthetic algae within the coral↔∞& to provide nutrients to their hosts. Hoπ≈λ≈wever, algae cannot survi≈βve in the absence of light, so deep♠€γ-sea corals need to rely on other®ε food sources for the↓↓ir nutrients, either♥£§ through organic materia∞≥™l falling from the su∏rface or by feeding on small plankton. Because d€₽α∏eep-sea corals lack algae, γ₽they are bright white in color rather than tφ×≥he browns and greens we see on shallow reefs. O✔>>ther species of coral, such as gorgonians, σ™black corals, and so♥•ft corals, add variety and color to deep-sea cora✘ ×l ecosystems.
This image shows the div±↓ersity of deep-sea coral species₩✘, including two octopus coral groups,
or sea fans (yellow and light grey p∏$'olyps), a stony cora↑•'l (white Lophelia pertusa),φ™ ₩ and a sea brevet (star brevis)
Like shallow reefs, deep-sea corals fo™$rm structures that provide habitat ™♥$for other invertebrates and fisφ±♥h, some of which are economically valua≈∑×ble. The death of shallow coral reefs due •₹παto human influence has '$been documented for λmany years, and although they areε€ very deep and have ×¥ε→the greatest distance frδ®←★om the shore, deep-sea corals↑♠✘α have not suffered from human influence in any ≈σ≈☆way.
As coastal resources were depleted, humans began ∏↓to search more deeply for new food ™• and energy sources. The biggest impact ₩§∞ on deep-sea corals c&←¶♦omes from commercial bot$★εtom trawling, which uses heavy eσ quipment to catch deep-sea fish ×εand, in the process, destroy structures that gr®←ow on the seafloor, such as§→♥♠ deep-sea corals. This type of fis£∞≠hing has damaged large areas of deep-sea coral€γ& reefs in domestic and inγγternational waters.
Corals are also harvest> ÷ed directly for their black, red or gold skeletoσns for use in jewelry and jewelry. These &quo€£φt;precious corals" are thought £₽ to be ancient and slo¥€♣w-growing -- in fact, the δ'$♠oldest known animal on Earth i€↔λ∑s a black coral that's over 4,250 year∞ ©s old.
Deep-sea corals are often found in oil '♦and gas extraction areas, so dr↓♦illing mud and oil spills have the potential t≥✘o cause damage. Deep-sea mining is fastβ becoming a reality, with l← arge-scale exploration and exploitation of the hi≠≥♦αgh seas. These miners✔✔Ω& are large and may permanently remove large area↕s of deep-sea coral habitat. In addition, the ¥∏future effects of climate change>> are less clear, but warmer te&λφmperatures may alter species distr€∏ibution, and increased acidity may weaken coraλ≥l skeletons, especially in the deep ↕™↕™ocean, where the eff≤♠≠ects of ocean acidification a₹<✘re thought to be gre↓φ× atest.
Much of the deep-sea coral research in t™£he Gulf of Mexico has been concentrated±"✘ in the northern regions where energy interest¥ ↓×s are concentrated, with relatively little<∑ in the eastern Gulf. One of the main purpos≥÷±es of the expedition wa×∑s to explore and charac♠©¥terize deep-sea coral communities✔∞δ₹ on the slopes of western Florida. Early surveys✘∏ in this area uncovered large an>π d thriving Lophelia reefs, as well as×π large black coral gatherings. However, multib>¶λeam surveys have revealed vast areas wher±'e there are many other promising properties th ♣↔♦at have never been explored.
Some known coral habitats have been prop ×↓osed as habitats of special concern (H→♠<εAPC) and any addition ♦©al information we provide ♣ will help support this process,'φ≈♣ as well as other management and conservation ♣€measures. While the establishment >>∞♦of new protected areas cannot completely prev¶ ent damage from oil spills or climate c δ♠hange, these areas can imφ✔prove coral health and resilience in the faceσ× of future threats.