Arthropoda Selecta 11 (2): 117134 © ARTHROPODA SELECTA, 2002 Copepoda (Crustacea) of hydrothermal ecosystems of theWorld Ocean Âåñëîíîãèå ðàêîîáðàçíûå (Crustacea: Copepoda) ãèäðîòåðìàëüíûõ ýêîñèñòåì Ìèðîâîãî Îêåàíà M.V. Heptner1, V.N. Ivanenko2 Ì.Â. Ãåïòíåð1, Â.Í. Èâàíåíêî2 1 () Zoological Museum, Moscow State University, Bolshaya Nikitskaya Str. 6, Moscow 125009 Russia. 1 () Çîîëîãè÷åñêèé ìóçåé ÌÃÓ, óë. Áîëüøàÿ Íèêèòñêàÿ 6, Ìîñêâà 125009 Ðîññèÿ. 2 Department of Invertebrate Zoology, Biology Faculty, Moscow State University, Moscow 119899 Russia; e-mail: [email protected] 2 Êàôåäðà çîîëîãèè áåñïîçâîíî÷íûõ, Áèîëîãè÷åñêèé ôàêóëüòåò ÌÃÓ, Ìîñêâà 119899 Ðîññèÿ. KEY WORDS: deep-sea hydrothermal vents and seeps, copepods, taxonomy, biology, functional morphology, distribution. ÊËÞ×ÅÂÛÅ ÑËÎÂÀ: ãëóáîêîâîäíûå ãèäðîòåðìû, õîëîäíûå âûñà÷èâàíèÿ, êîïåïîäû, òàêñîíîìèÿ, áèîëîãèÿ, ôóíêöèîíàëüíàÿ ìîðôîëîãèÿ, ðàñïðîñòðàíåíèå. ABSTRACT: Deep-sea hydrothermal ecosystems coida (8, 10, 11), Calanoida (2, 2, 2), Cyclopoida (1, 1, contain obligate taxa as well as species of oceanic 1) è Misophrioida (1, 1, 1). Îáëèãàòíî ãèäðîòåðìàëü- ecosystem. Thus ecological attribution of any species íûìè ÿâëÿþòñÿ ñåìåéñòâà Dirivultidae è Ecbathyrio- discovered in a hydrothermal biotope is a key task of ntidae (Siphonostomatoida) è íåêîòîðûå âèäû Poecilo- hydrothermal ecosystems investigation. 80 valid spe- stomatoida. Ôóíêöèîíàëüíî-ìîðôîëîãè÷åñêèé àíà- cies of 20 families from 6 orders of the 10 that form the ëèç ëîêîìîòîðíûõ è ðîòîâûõ êîíå÷íîñòåé ïîçâîëèë subclass Copepoda are discovered in deep-sea hydro- ñôîðìóëèðîâàòü ìîðôîëîãè÷åñêèå êðèòåðèè äëÿ thermal and seeping ecosystems. The most diverse order ïîíèìàíèÿ ñïåöèàëèçàöèè ãèäðîòåðìàëüíûõ êîïå- is Siphonostomatoida (4 families, 17 genera, 56 spe- ïîä. Dirivultidae íàèáîëåå ðàçíîîáðàçíû è ìíîãî÷èñ- cies), then Poecilostomatoida (4, 5, 9, respectively), ëåííû, ñïîñîáíû êàê ïëàâàòü, òàê è ïîëçàòü ïî ñóá- Harpacticoida (8, 10, 11), Calanoida (2, 2, 2), Cyclopoi- ñòðàòó, ïîãëîùàÿ áàêòåðèàëüíîå îáðàñòàíèå. ×àñòü da (1, 1, 1), and Misophrioida (1, 1, 1). Only Dirivultidae âèäîâ ñèìáèîíòû ãèäðîòåðìàëüíûõ áåñïîçâîíî÷- and Ecbathyriontidae (Siphonostomatoida) and some íûõ. Èõ áèîìàññà ïðåâîñõîäèò 2,85,8 ã/ì2 ïðè ÷èñ- species of Poecilostomatoida are interpreted as obligate ëåííîñòè áîëåå 64 000 ýêç/ì2.  öåëîì ôàóíà ãèäðî- for the deep-sea hydrothermal ecosystems. Functional òåðìàëüíûõ êîïåïîä èçó÷åíà íåäîñòàòî÷íî. analysis of locomotory and mouth limb morphology allows us to formulate morphological criteria for under- Introduction standing the specializations of hydrothermal copepods. Dirivultidae, the most abundant of these, are able to This paper is an improved English version of Copep- swim and crawl over the substrate, grazing on bacterial oda, a chapter of the monograph Biology of Hydro- films and mats. Some species are symbionts of hydro- thermal Systems edited by A. Gebruk [2002]. thermal invertebrates. Their biomass exceeds 2.85.8 g/ Copepods (subclass Copepoda Milne-Edwards, m2 with quantities of more than 64,000 ind/m2. As a 1840) are the most abundant animals living in diverse whole, the fauna of hydrothermal copepods is studied aquatic habitats, playing a significant role in marine life. insufficiently. In this paper we discuss the copepods of deep-sea hydrothermal fields and seeps, their taxonomic compo- ÐÅÇÞÌÅ: Ãëóáîêîâîäíûå ãèäðîòåðìàëüíûå ýêî- sition, distribution, morphological and biological traits, ñèñòåìû ñîäåðæàò êàê îáëèãàòíûå òàêñîíû, òàê è and the habitat specificity of obligate copepods [Hept- âèäû îêåàíè÷åñêîé ýêîñèñòåìû. Ò.î. äèàãíîñòèêà ner, Ivanenko, 2002]. ýêîëîãè÷åñêîé ïðèíàäëåæíîñòè ëþáûõ âèäîâ, îá- We believe that deep-sea hydrothermal ecosystems íàðóæåííûõ â ãèäðîòåðìàõ, ÿâëÿåòñÿ ïåðâîî÷åðåä- and deep-sea cold seeps related to them are immersed íîé çàäà÷åé ïðè èõ èññëåäîâàíèè.  ãëóáîêîâîäíûõ means in the ocean ecosystem and are ecosystems of ãèäðîòåðìàëüíûõ ýêîñèñòåìàõ îáíàðóæåíî 80 âè- the enclave type. Two biological consequences follow äîâ 20 ñåìåéñòâ 6 îòðÿäîâ èç 10, ñîñòàâëÿþùèõ from this: the influence of the hydrothermal systems on ïîäêëàññ Ñopepoda. Íàèáîëåå ðàçíîîáðàçíû Siphono- the oceanic ecosystem and vice versa. These influences stomatoida (4 ñåìåéñòâà, 17 ðîäîâ, 56 âèäîâ), çàòåì are important generally and for estimation of the role of Poecilostomatoida (ñîîòâåòñòâåííî 4, 5, 9), Harpacti- animals such as copepods that are not symbiotrophic, 118 M.V. Heptner, V.N. Ivanenko but consumers of the first order in hydrothermal eco- of ecological affiliation of the material collected from systems. hydrothermal biotopes. The first consequence is that some inhabitants of the hydrothermal zone and their developmental stages are Characteristics of the material and collec- carried away by currents. Vinogradov and Vinogradov [1998, 2002a,b] attempt to estimate the potential impact tion methods of the hydrothermal vent plume on the plankton above the Mid-Atlantic Ridge. They believe that the impact of At present, copepod species considered endemic to the hydrothermal plume on productivity of the ambient hydrothermal ecosystems are known from 20 areas in the oceanic water is negligible. However, planktonic hydro- Pacific and Atlantic oceans (Tables 1, 2). Hydrothermal thermal animals are distributed by the plume and are vents were discovered in over 40 localities and their recorded at a distance of up to 50100 km from a vent. number is still growing [Moskalev, 2002]. The source of Dispersal distances of vent fauna may be much greater the material is collections by expeditions of various than Vinogradov and Vinogradov [1968; 2002a,b] sug- countries. Most collections are from the Pacific Ocean, gest, as representatives of the obligate hydrothermal where initial investigations of the hydrothermal zone fauna are found in ephemeral habitats such as whale began. remains. At present, few such species are known, but their Interpretation of the available materials of copepods number is expected to increase [Tunnicliffe et al., 1998]. should include consideration of the fact that hydrother- There is a probability that a species described from mal ecosystems in the Pacific Ocean are entirely benthic non-vent habitat may eventually be recognized as an ones. The Atlantic hydrothermal zone is generally the obligate hydrothermal species. Until clear morphologi- same, but some bresiliid shrimps, principal components cal or other criteria are available, its ecological affilia- of ecosystems of the Mid-Atlantic Ridge, can be de- tion would remain questionable. Some indications of scribed as nektobenthic organisms. These shrimp may possible reproductive and physiological criteria may be be permanently in open water around a vent and/or at found in recent works [Vereshchaka et. al.,1998; Hour- some distance from it, and can withstand current drift up dez et al., 2000; Sell, 2000; Tsurumi et al., submitted]. to a rate of 17 cm/sec [Vinogradov, Vinogradov, 1998]. On the other hand, some widely distributed oceanic Among pelagic and benthic copepods, nektobenthic species may find favorable or more favorable conditions forms are unknown and unlikely, due to their small size in a hydrothermal ecosystem than in their original envi- (commonly 0.63.5 mm). Therefore, the whole list of ronment, and attain maximum abundance in the hydro- species known from hydrothermal vents is represented thermal zone. Such a phenomenon is described for some by either benthic or near-bottom forms, or by symbiotic oceanic species in the zone of an underwater mud species including parasites. volcano, Hokon Mosby, in the Norwegian Sea [Vino- We assume that all species of hydrothermal copep- gradov, Vinogradov, 1998]. If an undescribed animal is ods must be attached in some way to a substratum found with such a distribution, the problems are similar (either living or non-living); otherwise they would be as in the case of hydrothermal organisms found beyond swept away from their habitat. This general ecological the hydrothermal zone. For example, the family Erebon- requirement permits evaluation of available specimens asteridae (Copepoda: Poecilostomatoida) was discov- for their suitability to such a habitat and, in addition, of ered by Humes [1987] in mantle cavity of a protobranch the occurrence of appropriate substrata for coloniza- bivalve and termed endemic to the hydrothermal zone. tion by specialized hydrothermal copepods. Therefore, Subsequently, new species and genera of this family if new species that are typical planktonic forms are were found in other deep-sea biotopes [Huys, Boxshall, found in hydrothermal vents they can be inferred to 1990; Huys, 1991]. have drifted into the hydrothermal zone from an adja- One reason for both problems is paradoxical: the cent ecosystem. recently discovered hydrothermal zone has been more The vent copepod materials we consider here are thoroughly investigated than the adjacent non-vent oce- collected by three main methods. Copepods living in the anic benthic zone, although the non-vent benthic zone ground or on its surface are collected by a box corer. has been investigated for many decades. Moreover, the Species living among benthic animals are collected by a fauna of hydrothermal vents may be considered the best special sucking device a slurp gun. Commensal known of all deep-sea ecosystems; further exploration is species are washed off such principal substratum-form- constrained by insufficient knowledge of the adjacent ing species of the hydrothermal community as vestimen- benthic