Artifact #2

Brian Santoleri

4/29/2012

Ecological Principles

Part III – Energy Flow

Hydrothermal Vent Ecosystems of the Mid-Atlantic Ridge

Deep-sea hydrothermal vents form as a result of volcanic activity on the ocean floor. The area of diverging tectonic plates at the Mid-Atlantic ridge, make its active sea floor a hot spot for ecosystems surrounding hydrothermal vents. Because sunlight does not reach the depths between 1500-2500 feet in the Atlantic Ocean, these ecosystems rely on hot, nutrient and mineral rich water, spewed for the vents, as its main energy source. By the process of chemosynthesis, bacteria can cultivate this energy source and colonize areas along vent networks.  Until discovered some 30+ years ago, life at these depths was not known or even believed to have occurred. With advances in remote operated marine technology, we now have recorded video and a variety of sediment, organism, water and other samples of a once unknown ecosystem, which thrives in places no man has the ability to venture to.

Some of the largest and longest-lived hydrothermal vents have been discovered the slow-spreading Mid-Atlantic Ridge. In 1992, during the US mission FAZAR, a new site was discovered at 37°18′N, 1700 m deep later named Lucky Strike. A preliminary study of the communities’ composition at this site was done during six dives of the US deep research submersible ALVIN1 and suggested the existence of two distinct biogeographical provinces on the Mid-Atlantic Ridge (Van Dover, 2000). Also, recently in August of 2011, an Irish led group of marine biologists discovered a field of hydrothermal vents along the Mid-Atlantic Ridge using a remotely-piloted sub called the Holland I. “The field's tallest chimney stands more than 32 feet tall in an area just north of the Azores islands at an latitude of 37°50’N.” National Geographic, 2011) Dr. Bramley Murton of the National Oceanography Centre in the UK, who first saw clues for possible vents on an expedition aboard the UK research vessel RRS James Cook in 2008 and who led the mineralisation study on the expedition, said, "Our discovery is the first deep-sea vent field known on the Mid-Atlantic Ridge north of the Azores.” (National Geographic, 2011) The figure below shows the areas where hydrothermal vents have been discovered on a global scale. The yellow dots are areas on the Mid Atlantic Ridge where vent zones have been found and are sites where these vents are active today.

Table. 1 Hydrothermal Vent Food Web

Hydrothermal vents offer a mine of energy, in the form of fluids coursing through the vents, which carry compounds rich in electrons and metals. These columns of water, which rise from seafloor hydrothermal vents, consists mostly of “sea water drawn into the hydrothermal system close to the volcanic networks through faults and porous sediments or volcanic strata, plus some magmatic water released by the upwelling magma”(Fisher, 2003). This so called “vent fluid” is geothermally heated close to the magma chamber that feeds the ridge, reaching temperatures that can exceed 400°C until mixed in with colder water. “The fluid is also chemically modified, losing all dissolved oxygen and accumulating high concentrations of dissolved reduced gases such as methane and hydrogen sulfide”( Ramirez-Llodra, 2007), making it strongly acidic with a pH of 2–3.  “Samples have shown that vent fluids are rich in numerous metals—dominantly iron, manganese, copper, and zinc, but also precious metals such as silver, gold, and platinum, as well as highly toxic ones like cadmium, mercury, arsenic and lead.”(Desbruyeres, 2000) It is these vent fluids that provide the necessary energy, in the form of reduced chemicals, for the development of the rare faunal communities found at vents.

Hydrothermal circulation occurs at mid-ocean ridges when dense, cold seawater seeps downward through fractured oceanic crust near the ridge crest. As you can see in the diagram below, there are areas other than the main “black smoker” vent where the vent fluids and steam from the volcanic activity arise from areas surrounding the main vent. This process is called difuse venting.  “In terrestrial hydrothermal systems, the majority of water circulated within the fumarole and geyser systems is meteoric water plus ground water and also commonly contains some portion of metamorphic water, magmatic water, and sedimentary formational brine that is released by the magma.”(Tsurumi, 2003) The proportion of each body of hydrothermal water varies from location to location and has a direct effect on the overall ecosystems present in that area.

Image 1: Formation of Hydrothermal Vent via Discharge Reaction

Wildlife on the ocean floor use the energy from the water to build an ecosystem in this seemingly unlivable environment. Despite their unusual nature, ecosystems based on chemosynthesis are tied together by food webs similar to those of better-known communities. The hydrothermal vent food web below has four layers: Primary Producers, Primary Consumers, 1^st order carnivores, and top order carnivores. As seen in table 1, the simple chemicals produced from the vents, like carbon dioxide, oxygen, hydrogen sulfide, and methane, are ingested by symbiotic and vent bacteria. In order for a hydrothermal vent to be colonized and support life, these kinds of chemotrophic bacteria must perform the process of oxidizing expelled chemicals to produce energy, known as chemosynthesis.  “Because most fauna on the ocean floor lack oral cavities or the internal metabolic means to utilize the energy flow”(Nambiar, 2001), symbiotic microbes have a crucial role in supporting life. The microbes are found free-living as well as in highly successful symbiosis with many of the macroinvertebrates inhabiting the vent habitat.

Primary consumers in this ecosystem, such as vent clams, mussels, shrimp, zooplankton, ext., get their energy directly from the primary producers by eating or living symbiotically with them. The Vent Mussel, Bathymodiolus childressi converts the methane from bacteria inside them into food. Another primary consumer, the Pompeii Worm (figure 3), Alvinella pompejana, is the “most heat tolerant animal on earth, able to withstand living in water as hot as 176^oF” (Tunnicliffe, 1991). Bacteria grow in strands on the back of this organism, which are then fed on by the worm.

First order carnivores prey on the primary consumers and in turn are eaten by other animals. Zoarcid fish, Pachycara gymninium, are two-foot long, white fish, which are considered the top predators of tube worms, shrimp, mussels, and other organisms in the vent ecosystem. Another interesting species, whom are closely related to the Portuguese Man-O-War, is the Dandelion Siphonophores (see figure 4). This species use its whisker-like tentacles to anchor to rocks and sting its prey, mostly shrimp, and also are well known scavengers.

Image 2: Geographic locations of known hydrothermal vents

Top order carnivores eat other consumers and carnivores but are rarely hunted by other creatures. Because they are separated from the primary food production by several layers, top order carnivores have the smallest biomass in the food web. Among this order of carnivores is the Dumbo Octopus (see figure 5), Grimpoteuthis, which hovers above the sea floor, searching for polychaetes, copepods, isopods, amphipods, and other crustaceans for food. “The Dumbo octopus is strange in the way it consumes food in that it swallows its prey whole, which differs from any other kind of octopus.”(Wikipedia, 2012) Also, the Vent Ratfish, Hydrolagus affinis, is considered a top order carnivore, preying on smaller animals like crabs, mussels, and smaller fish.

According to Cindy Lee Van Dover, a Professor of Biological Oceanography at Duke University Marine Laboratory, the number of explored deep-water vent sites on the Mid-Atlantic Ridge has doubled every year since 1995. “The fauna of Atlantic vents consists for the most part of a subgroup of invertebrate types found elsewhere in chemosynthetic ecosystems, with taxonomic differentiation usually at the species or genus level.”(Van Dover, 1997) If you have noticed on table 2, most organisms that have been identified have not been given a species or scientific name at this time. These ecosystems need to be found and studied carefully not only for the areas of ecology and biology, but the possibility life on other planets and also evidence of potential cures in the medical world. If these highly metallic and gaseous vent fluids can support a marine ecosystem, completely hidden from solar energy, there is the possibility of life on any planet with water. 

Figure 3 Dandelion siphonophores 

      Figure 4 Alvinella pompejana    

Resources Cited

Bermudez, Cheri. "The Biology of Hydrothermal Vent Ecosystems." Cheri Bermudez on HubPages. N.p., n.d. Web. 22 Apr. 2012. <http://cheribermudez.hubpages.com/hub/The-Biology-of-Hydrothermal-Vent-Ecosystems>.

Desbruyeres, D. , A. Almeida, and M. Biscoito. "A review of the distribution of hydrothermal vent communities along the." Hydrobiologia 440.1-3 (2000): 201-216. Springer Link. Web. 20 Apr. 2012.

Fisher, Robert L., Edward D. Goldberg, and Charles S. Cox. "20." Coming of age: Scripps Institution of Oceanography : a centennial volume, 1903-2003. San Diego: Scripps Institution of Oceanography, University of California, 2003. 1-14. Print.

Gonzalez-Rey, M., A. Serafim, R. Company, T. Gomes and M. Bebianno. “Detoxification Mechanisms in Shrimp: Comparative Approach Between Hydrothermal Vent Fields and Estuarine Environments.” Marine Environmental Research. 66 (2008): 35-37.

Hydrothermal vent - Wikipedia, the free encyclopedia." Wikipedia, the free encyclopedia. N.p., n.d. Web. 12 Apr. 2012. <http://en.wikipedia.org/wiki/Hydrothermal_vent>.

LANGMUIR, C., S. HUMPHRIS, and D. FORNARI. Hydrothermal vents near a mantle hot spot: the Lucky Strike vent field at 37oN on the Mid-Atlantic Ridge. Palisades, NY: Elsevier, 1997. Print.

Nambiar, A.R.. "Hydrothermal Vent Ecosystem." ENVIS Centre on Marine and Marine Offshore Ecosystem-Department of Geology,University of Kerala. N.p., 14 Dec. 2001. Web. 22 Apr. 2012. <http://dgukenvis.nic.in/artmar1.htm>.

National Geographic. "National Geographic Society Press Room: Press Release Detail." Major Scientific Discovery on the Mid-Atlantic Ridge . N.p., 13 Aug. 2011. Web. 30 Apr. 2012. <http://press.nationalgeographic.com/pressroom/index.jsp?pageID=pressReleases_detail&siteID=

Ramirez-Llodra, Eva, Timothy Shank, and Christopher German. "Biodiversity and Biogeography of Hydrothermal Vent Species." Oceanography 20.1 (2007): 30-42. WHOAS. Web. 13 Apr. 2012.

Tunnicliffe, V. “The biology of hydrothermal vents: ecology and evolution.” Oceanography And Marine Biology An Annual Review 29.0 (1991) : 319-407.

Tsurumi, Maia. “Diversity at hydrothermal vents.” Global Ecology and Biogeography 12.3 (2003) : 181-190.

Van Dover, C L. The Ecology of Deep-Sea Hydrothermal Vents. Princeton University Press, 2000.

"WWF - Deep sea ecology: hydrothermal vents and cold seeps." WWF - WWF. N.p., n.d. Web. 16 Apr. 2012. <http://wwf.panda.org/about_our_earth

Phylum	Subphylum	Genus	Species
Porifera	Hexactinellidae	Asbestopluma	pennatula
Table 2. Faunal composition of the vent communities recorded in the regions of the Mid-Atlantic Ridge.		Asbestopluma	infundibulum
		Cladorhiza	aff. grimaldi
		Euchelipluma	pristina
Cnidaria	Anthozoa	Stegolaria	geniculata
	Hydrozoa	Candelabrum	phrygium
		Eudendrium	sp.
		Eudendrium	rameum
		Cladocarpus	formosus
Annelida	Polychaeta	Amathys	lutzi
		Archinome	sp.
		Branchipolynoe	aff. seepensis
		Capitella	sp.
		Eunice	norvegica
		Cf. Hesiolyra	sp.
		Levensteiniella	n. sp.
		Lugia	sp.
		Opisthotrochopodus	n. sp.
		Spiochaetopterus	sp.
		Prionospio (Minuspio)	n. sp.1
		Prionospio (Minuspio)	sp.2
		Prionospio	sp.3
Mollusca	Monoplacophora	Rokopella	n. sp.
	Gastropoda	Alvania	n. sp.
		Amphissa	acuticostata
		Calliostoma	obesula
		Dendronotus	comteti
		Emarginula	sp.
		Laeviphitus	n. sp.
		Lepetodrilus	n. sp.
		Lirapex	n. sp.
		Mitrella	nitidunila
		Neusas	marshalli
		Orbitestella	n. sp.
		Orbitestellidae n. gn.	n. sp.
		Paraletopsis	n. sp.
		Peltospira	n. sp.
		Phymorhynchus	n. sp.
		Protolira	valvatoides
		Protolira	thorvalldssoni
		Pseudorimula	midatlantica
		Pseudosetia	azorica
		Shinkailepas	n. sp.
		Strobiligera	brychia
		Xylodiscula	n. sp.
	Bivalvia	Bathymodiolus	azoricus
Arthropoda	Pycnogonida	Sericosura	heteroscela
	Halacarida	Halacarellus	alvinus
		Copidognathus	alvinus
	Cirripeda	Altiverruca	longicarinata
		Poecilasma	aurantia
		Poecilasma	crassa
		Verum	n. sp.
	Copepoda	Aphotopontius	atlanteus
		Aphotopontius	temperatus
		Stygiopontius	rimivagus
	Ostracoda	Bathyconchoecia	pauluda
		Bairdia	sp.
		Bythocypris	sp.
		Krithe	sp.
		? Pontocypris	sp.
	Amphipoda	Luckia	striki
		Bouvierella	curtimana
		Gitanopsis	alvina
	Decapoda	Acanthephyra	eximia
		Acanthephyra	purpurea
		Kemphyra	sp.
		Nematocarcinus	exilis
		Chaceon	affinis
		Paromola	cuvieri
		Segonzacia	mesatlantica
		Alvinocaris	aff. markensis
		Mirocaris	fortunata
		Chorocaris	chacei
		Rimicaris	exoculata
Echinodermata	Echinida	Echinus	alexandri
	Ophiurida	Ophioctenella	acies
Chordata	Chondrichthyes	Apristurus	maderensis
		Etmopterus	princeps
		Centroscymnus	coelolepis
		Deania	profundorum
		Hydrolagus	affinis
		Hydrolagus	pallidus
	Osteichthyes	Cataetyx	laticeps
		Chaunax	sp.
		Chiasmodon	niger
		Coelorhynchus	labiatus
		Epigonus	telescopus
		Gaidropsarus	n. sp.
		Halosaurus	johnsonianus ?
		Guttigadus	latifrons ?
		Lepidion	schmidti
		Lycenchelys	n. sp.
		Mora	moro
		Nezumia	sclerorhynchus
		Polyacanthonotus	rissoanus
		Simenchelys	parasitica
		Synaphobranchus	kaupi
		Trachyscorpia	cristulata echinata