Marine Flora and Fauna of the Northeastern 

 United States. Scleractinia 



STEPHEN D. CAIRNS' 



ABSTRACT 



This manual discussi-s Ihc 14 species <it silcrucliniuii corals known IVom (he nortlu-aslcrn I niied Males coasi 

 from \ ir^inia (o No\a SeoCia. tollowin^ a hrJet inlroduelion to (he ceiUTal l>inlot;> and ni<irphnlo};;> nt 

 Scleraclinia. an illiislraled dicholomons ke> and (ho (ahnlar ke>s are t£i%en t<»r ihese species. An annota(ed 

 s\s(ema(ic lfs( includes complete i:eot>raphic and hath>me(rie ranges, relerences lo pi>rlinen( lileralurc, and. fur 

 some species, ecological and (avonomic nt»les. /oo^eo^raphic urfinilies nl' the I'auna are brielU discussed. A 

 selec(ed hihlio|^rapli> is provided. 



INTRODUCTION 



Fourteen species of stony corals (order Scleractinia) are 

 known from off the northeastern coast from Chesapeake Bay to 

 southern Nova Scotia of which only one, Astrangia 

 astreiformis, occurs at depths shallow enough to be collected 

 routinely by snorkeling or scuba diving. The remaining species 

 are usually collected by benthic trawls or dredges and occur as 

 deep as 3,200 m off the northeast coast. Much research has been 

 done on the easily accessible A . asireiformis, but little more than 

 physical descriptions and distributions are known for the deeper 

 water species. All 14 species are included in this report. 



Of these 14 species, 13 are ahermatypic; i.e., they do not 

 possess symbiotic zooxanthellae (a unicellular dinoflagellate) in 

 their endodermal tissue. Individual colonies of A. asireiformis 

 may or may not have zooxanthellae, depending perhaps on 

 water temperature or light intensity; more frequently this species 

 lacks the symbionts. The term ahermatypic is thus a 

 physiological condition determined by ecological factors and 

 therefore is not a character of great value in classification. 



Ahermatypic corals have been equated with deepwater corals, 

 solitary corals, or nonreef building corals. This is an 

 oversimplification; in fact, many species occur in shallow water, 

 and some large, colonial deepwater (500-800 m) ahermatypes 

 (e.g., Lophelia prolifera, Enallopsammia profunda) form the 

 framework for reeflike structures. It is true, however, that all 

 deepwater corals are ahermatypic because below the euphotic 

 zone the zooxanthellae, being plants, cannot photosynthesize. 

 Not restricted by the generally higher (often tropical) 

 temperature and light requirements that zooxanthellae impose 

 on hermatypic corals, the ahermatypes inhabit a more extensive 

 geographic range. They are found in all oceans from the 

 Norwegian Sea (lat.70°30 'N) to the Ross Sea, Antarctica 

 (lat.78°29 S). from 0-6,328 m depth (Keller 1976), and in 

 temperatures of - l.rc to over 29°C. 



Scleractinia are monoecious or dioecious; in either case their 

 motile larva] form is a planula capable of remaining planktonic 

 for weeks. In addition to sexual reproduction, some species 

 propagate by asexual budding and others have remarkable 

 powers of regeneration. For instance, the corallum of 

 Dasmosmilia lymam usually splits longitudinally into several 



Ucpanmcni of Invcnibraii; Zoolog>, National Museum ol Naiutal Hisui 

 Sniiihsoniaii Imiilulion. \Vashiiii;ioii. D.C. 20560. 



fragments, each wedge-shaped piece subsequently producing 

 1-30 small buds growing directly from the mesenterial tissue. It 

 is rare to find a specimen of D. lymani that grew directly from a 

 planula, i.e., not attached to an inside fragment of a parent 

 specimen. 



All planulae need a hard substrate on which to settle. 

 Following settlement and subsequent growth, corals may either 

 remain attached to the substrate or become free, lying 

 unattached on the substrate. The attached corallum usually 

 reinforces its base of attachment by various means, whereas the 

 subsequently unattached corallum becomes free by lacking 

 reinforcement of an originally weak attachment or by 

 completely overgrowing the substrate, as in the case of a sand 

 particle. Some unattached species (e.g., Caryophyllia ambrosia) 

 become top-heavy, fall to one side, but subsequently reorient 

 their calices toward an upright position, producing a horn- 

 shaped corallum. 



The scleractinian fauna of the northeastern coast of the 

 United Stales is relatively low in diversity when compared to 

 other areas in the western Atlantic, even when the reef corals 

 (hermatypes) are excluded from consideration. For example, 

 there are approximately 160 species of Scleractinia in the 

 Caribbean: 76 deepwater (over 200 m) ahermatypes (Cairns 

 1979), about 30 exclusively shallow-water ahermatypes, and 

 about 54 hermatypic species. In the region between north 

 Florida and Cape Hatteras there are about 40 species known: 28 

 deepwater ahermatypes (Cairns 1979), about 8-10 exclusively 

 shallow-water ahermatypes, and several hardy hermatypic 

 species, i.e., Solenoasirea, Siderastrea, Oculina. In the western 

 Atlantic north of the North Carolina-Virginia border there are 

 17 species known, 16 deepwater ahermatypes and one 

 exclusively shallow-water species, A. asireiformis. Fourteen of 

 these 17 species are treated in this work, the other three: 

 Vaughanella margariiaia (Jourdan, 1895); Fungiacyathus durus 

 Keller, 1976; and F. marenzelleri (Vaughan, 1906) are known 

 from localities north of Maine. Other species occurring south of 

 the area of consideration for this manual that may subsequently 

 be found there include: Dendrophyllia gadilana (Duncan, 1873); 

 Pourialosmilia conferla Cairns, 1978; Concentrolheca 

 laevigala (Pourtales, 1871); and Polymyces fragilis (Pourtales, 

 1868). 



The 14 species of Scleractinia known from off the 

 northeastern coast of the United States are, in general, widely 

 distributed species. Six are cosmopolitan and seven are amphi- 



