COBISS: 1.01 Patterns and Processes OF Groundwater Invasion BY Copepods in the Interior Low Plateaus OF the United States Vzorci in procesi naseljevanja ceponožcev V podzemeljske vode na planoti Interior Low Plateaus V Združenih državah Julian J. LEWIS1 & Janet W. REID2 Abstract UDC 574.9:595.34 (7) Izvleček UDK 574.9:595.34 (7) Julian J. Lewis & Janet W. Reid: Patterns and Processes of Julian J. Lewis & Janet W. Reid: Vzorci in procesi naseljevanja Groundwater Invasion by Copepods in the Interior Low Pla- ceponožcev v podzemeljske vode na planoti Interior Low Pla- teaus of the United States teaus v Združenih državah The copepod crustacean fauna collected from subterranean Med ceponožnimi raki, vzorčevanimi v podzemeljskih habi- habitats, including caves, wells, and the hyporheos of streams tatih, v jamah, vrtinah in rečnem hiporejiku blizu ter na sami in and near the Interior Low Plateaus of the United States is planoti Interior Low Plateaus (ZDA), prevladujejo ciklopoidi dominated by Cyclopoida, with 39 species, followed by Harpac- z 39 vrstami, sledijo jim harpaktikoidi z devetimi vrstami in ticoida with 9, and Calanoida with 2. Nearly all of the harpac- kalanoidi z dvema vrstama. Skoraj vse identificirane harpakti- ticoid and calanoid species are widespread, primarily surface- koidne in kalanoidne vrste so splošno razširjene, površinski dwelling generalists. Fourteen of the cyclopoids, members of generalisti. Štirinajst ciklopoidnih vrst, predstavnikov rodov the genera Diacyclops, Itocyclops, Megacyclops, and Rheocyclops, Diacyclops, Itocyclops, Megacyclops in Rheocyclops, je stigobion- are apparently obligate stygobionts or hyporheic. Several of the tov ali prebivalcev hiporejika. Vrste, ki imajo močneje izražene species that are more strongly modified for subterranean exis- prilagoditve na podzemeljsko življenje, najdemo v južnih pre- tence occur only in the more southern, unglaciated areas. Our delih, ki v času ledenih dob niso bili pokriti z ledenim pok- sampling data support the hypothesis that the more specialized, rovom. Rezultati vzorčenja podpirajo hipotezo, da tiste vrste, groundwater-interstitial species have been unable to disperse ki so bolj specializirane na podzemeljske-intersticialne pogoje into previously glaciated regions; whereas some, less-special- niso bile sposobne razširjenja v predhodno poledenele predele; ized species may have invaded groundwaters from surface habi- medtem ko so nekatere, manj specializirane vrste ob umikanju tats as the glaciers receded. ledenikov uspele prodreti iz površinskih v podzemeljske vode. Key words: Copepoda, Crustacea, biogeography, glaciation, Ključne besede: Copepoda, Crustacea, biogeografija, polede- North America. nitev, Severna Amerika. Introduction We review published information and present new geo- relative lowlands between the Appalachians to the east graphical records for the copepod crustaceans collected and the Ozark Plateaus to the west. The ILP stretches from subterranean habitats in and near the Interior Low from northern Alabama, northward through Tennessee Plateaus (ILP) physiographic province of the United and Kentucky into southern Indiana and Illinois. Much States. Fenneman (1938) described the ILP as an area of of this area is karst topography and contains thousands 1 Lewis & Associates LLC, Cave, Karst & Groundwater Biological Consulting, 17903 State Road 60, Borden, IN 47106-8608, U.S.A.; e-mail [email protected] 2 JWR Associates, 1100 Cherokee Court, Martinsville, VA 24112-5318, and Research Associate, Virginia Museum of Natural History, U.S.A.; e-mail: [email protected] Received/Prejeto: 07.02.2007 ACTA CARSOLOGICA 36/2, 279-289, POSTOJNA 2007 Julian J. LEWIS & Janet W. REID of known caves. The northern boundary of the ILP is the by Yeatman (1964). Barr (1967) summarized collections terminus of the Illinoian glaciation. Herein we trace the of 17 taxa reported from Mammoth Cave and other caves present-day distribution of the copepod species in this in the central Kentucky karst by his own field work, as region, and attempt to infer the historical patterns and well as that of Kofoid (1899) and Chappuis (1931). routes of their re-entry into previously glaciated areas. Lewis began sampling cave faunas in the eastern The Interior Low Plateau region has been the focus United States in the 1970s, but only started focusing at- of many earlier studies relating to the fauna of caves and tention on the micro-crustacean fauna in the 1990s (Lew- karst, because of the notoriety of some local sites, espe- is, and Lewis et al. 1998-2006). The initial impetus for cially in the central Kentucky karst, including what is these collections was the desire to rediscover Diacyclops now Mammoth Cave National Park. In 1928, C. Bolívar jeanneli in Marengo Cave and the surrounding area dur- and René Jeannel made collections of copepods from ing a survey conducted for The Nature Conservancy in numerous caves in the eastern United States, resulting in Indiana. The results from this sampling made it clear that the first descriptions (Chappuis 1929, 1931) of subterra- a significant assemblage of subterranean microcrusta- nean copepod taxa from this country: Megacyclops don- ceans was present in the groundwaters of the midwestern naldsoni (Donnaldson Cave, Lawrence County, Indiana), United States. Presented herein are the results of Lewis’ Diacyclops jeanneli (Marengo Cave, Crawford County, approximately 15 years of sampling. Newly described Indiana), and Bryocamptus morrisoni (Horse Cave, Hart copepod taxa resulting from these collections are Rheo- County, Kentucky; and Donnaldson Cave). Cyclops clan- cyclops indiana (Reid et al. 1999), Diacyclops salisae, D. destinus (renamed Diacyclops yeatmani by Reid, 1988) lewisi, D. indianensis and D. conversus (Reid 2004), and a was described from Big Mouth Cave, Grundy County, new species of Itocyclops (Reid in review). Tennessee and a drain tile in Vermilion County, Illinois Sampling methods A variety of means were used to collect copepods from were left overnight and then retrieved. Longer trapping different windows into the groundwater. Plankton drift intervals appeared to result in fouling of the water and samples were collected by hanging a plankton net over decrease in the fauna that was captured. Finally, a Bou- the orifice of a spring, in a flowing cave stream, or at the Rouch pumpwell was used to sample hyporheic inter- mouth of a drain tile. In deeper streams, rimstone pools, stices of the Blue River in southern Indiana. or drip pools in caves, the net was drawn through the All samples were transported alive to the laboratory water. In shallow drip pools, fed by the epikarst, water for visual inspection. The copepods and other fauna were was dipped with a cup and strained through the plank- much easier to detect alive than preserved. The animals ton net. In cave streams with sufficiently deep gravel, the were removed from the sample with an eye dropper, and Karaman-Chappuis technique was used to gather fauna then preserved in 70% ethanol. Voucher specimens were living in the interstices. In wells, copepods and other deposited in the collections of the National Museum of fauna came readily to jars equipped with perforated lids Natural History (Smithsonian Institution), or the Vir- and baited with a single, uncooked dead shrimp; these ginia Museum of Natural History. Patterns OF distribution and habitat Like any other puzzle, a modicum of the pieces have to One of the ecological fortes of cyclopoid copepods be gathered and arranged before even a hint of the overall of the genus Diacyclops is their use of groundwater habi- picture begins to emerge. Enough sampling from caves tats, and it appears that some species are indeed stygobi- and other windows into groundwater in the Interior Low onts. The best-known of these in the United States isDia - Plateaus of the east-central United States has now been cyclops jeanneli. For many decades after its discovery in conducted to permit a few observations about the pat- 1928, this species remained obscure, with even its micro- terns of distribution, as well as to infer the processes by habitat in Marengo Cave uncertain. Using shrimp-baited which copepods have invaded this realm. jar traps, Lewis (1996) found D. jeanneli in a well, not 280 ACTA CARSOLOGICA 36/2 – 2007 Patterns and Processes OF Groundwater Invasion BY Copepods in the Interior Low Plateaus ... associated with caves or karst, on the edge of the Knob- Diacyclops yeatmani has now been recorded from stone Escarpment, in Floyd County, Indiana. This well the hyporheos of the Blue River in southern Indiana, a had been hand-dug many decades earlier, penetrating al- drain tile in glaciated Illinois, and three caves in Tennes- luvium and then the top of the New Albany Shale to a to- see. This is remarkable because the species is distributed tal depth of 21 feet (6.4 m) below the surface. Also found both south of the Illinoian glacial maximum, and a sig- in the well was the phreatobitic isopod Caecidotea tere- nificant distance north of it, in the till plains of Illinois. sae, previously known from a series of drain tiles across A somewhat similar distribution pattern is known for D. the street on the Indiana University Southeast campus in indianensis, which is recorded from the type-locality in New Albany, associated with an undescribed groundwa- a cave in glaciated southeastern Indiana, and from seven ter amphipod Stygobromus sp. (Lewis 1982). caves in Tennessee. In Indiana D. indianensis occurs in a At the time that D. jeanneli was first collected from cave about 20 km outside the Illinoian glacial boundary Marengo Cave, a relatively small amount of passage had region, whereas D. yeatmani occurs perhaps 80-100 km been explored, and none of the known passages con- inside this boundary. tained a significant stream. Since that time, not only one, Several other species of Diacyclops are presently but two, cave “rivers” have been connected by explorers known from one or two sites in southern Indiana: D. to the historic section of Marengo Cave. Lewis (1998) lewisi, D. salisae, D. conversus.