Assessment of Reef Fishes at Sombrero Key, Florida T. E

ASSESSMENT OF REEF FISHES AT SOMBRERO KEY, FLORIDA

T.E. Thompson D. G. Lindqtast L E. Ckrvijo S. K. Bolden S. W. Burk N. C. Drayton Departmentof Biological Sciencesand Center for Marine Science Research Universityof North Carolina Wilniington,NORTH CAROLINA 28403-3297U.S.A.

Wequantitatively assessed the reeffish assemblageat SombreroKey, a bankreef off' the middle Florida Keys,during May 8-11,1988 using the stationarysurvey method. Wedivided the reef fish assemblageintothree depth zones < 3m,3'-6 m, and 6-10m!. Thesezones approrimated, respectively, the Millepora ridge zone 1!, the Acropora palmataarea zone2!, and the reeffront basewhich was characterizedby moresand and /esscoral cover zone3!. Eighty-eightspecies in 27 families, representedmainly by pomacentrids,labrids, and haemuiM were observedin all zones.The largest number of individualsand thehighest Shannon speciesdiversity occurred in zone1, however,species richness was higher in zones 2 and 3.

INTRODUCTION

Coral reef fish assemblagesare complexand there existsa lack of quantitativedata concerningabundance and distribution patterns of fishspecies, particularly for Caribbeanand Florida reefs Alevizon et al. 1985,Bohnsack et al. 1985!. This has resulted in a lack of understandingof the factorswhich govern the structureof coral reef fish asseinblages.Most studieshave dealt with smallpatch reefs, artificial reefs,or discreetportions of a largerreef systein Ogden 1982!. Only a fewstudies have dealt with reef fish abundanceand distribution by depth. Tilmant 984! surveyedthe literatureconcerning Florida coral reefsand found a characteristicspecies composition associated with differentreef typesand depthzones within a particularreef. Alevizon et al. 985! foundfish speciescomposition and abundanceto vary significantlywith depth at Deep Water Cay locatedof'f Grand BahamaIsland. However, variationin fish communitystructure was influenced by coral zonation rather thandepth itself. Bohnsacket al. 985! found that fish speciesoccurrence and abundancevaried with habitat associatedwith different depthzones on Looe Key Reef.

375 Divingfor Science-.19Ã

Coralreef nshery resources of Floridaand the Caribbean are facing increasing utilization andadverse environmental pressure by man. Usesinclude commerciai fishing, recrea- tional fishing,spearfishing, and collecting. Although someof Florida's coral reefs havebeen designatedas sanctuaries,all are facedwith an increasein diving and boatingactivities. 7i aditionallyviewed as nonconsiipptiv, diving activities may now be a significantdisturbance in someareas. In addition, Florida's coral reefs appear to be suffering from poor water quality associatedwith increased development of the Florida Keys and south Florida, in general Whrd 1990!.Proper manageinent of coralreef fisheriesrequires quantitative information concern- ingfish abundance, distribution, and structure of thefish assemblages.

Theobjective of thispaper is to providequantitative data regarding reef fish abundance anddistribution by depth zones within the Sombrero Key reef. Thisreef is currentlynot protectedunder any sanctuary designation and has received increased disturbance byway of divingand spearfishingactivities. Our null hypothesisis that there is no differencein Gsh speciesdiversity, incan fish species richness, and fish species abundance in three vertical depth zoneson the coral reef defined as < 3 m, 3-6 m, and 6-10 m.

METHODS

StadyArea

All visualsampling was conducted at SombreroKey located within the FloridaReef Tractapproximately 8 km south of Boot Key and 35 km northeast of LooeKey National Marine Sanctuary.Sombrero Key has well defined spur and groove forinations on the seawardside downto about 92 m. The tops of some spurs may be awash atlow tide. The shoreward edge of thereef is surrounded bysand interspersed withseagrass beds ?%dahlia testudiruurr!. Below10 m thespur and groove forinations give way to a combinationofsand mixed with low profilelimestone covered with octocorals andsponges. Wedivided the reef into three depth zones.Zone 1 beganatthe top of the reef and ended at a depthof 3 m.Zone 2 rangedfrom 3 mto 6 m.Zone 3 startedat6 mand ended at the bases of thespur formations in 10 m of water.

SamplingTechniiine Samplingwas conducted between 0900 and 1530 hours on May 8th through the 11th, 1988with the exception ofMay 9th when sea conditions precluded safe diving. Six SCUBA divers,working inpairs, used the stationary visual survey methods ofBohnsack and Bannerot 986!.Each pair of divers began a sample ina zonebyseparating from one another a distance ator just beyond the limit of visibility. In some cases, the pair were not able to see one another suchas when sainpling opposite sides of a spur.However, efforts were made to stay within easyswimming distance forsafety considerations. Eachdiver began by facing seaward and

376 Thompsonet aL ReefFishes at SombreroKey, Flonda listing all speciesseen within an imaginarycylinder stretching from the bottom to the surface. A radiusof 7.5 m was usedsince Bohnsack and Bannerot 9&6! determinedthat this radius maxinnzedthe number of speciesand individuals that a divercould observe including cryptic andshy species. The diverrotated clockwise and listed species for 5 minutes.This usually requiredseveral rotations. Except for speciesnot likely to remainin thearea such as carangids, individualsof a specieswere not countedduring the first 5 minutes.

Abbreviatedscientific names using the first threeletters of thegenus and first four of the speciesaided in efficientcoding of dataonto water proof datasheets. At the endof 5 minutes,numbers of eachspecies within the samplingarea were counted beginning at the bottomof thelist andworking up. Afterall specieshad been counted, the percentage of sand, limestone,gorgonia, and hard coral was estimated for eachsample. Each sample required 15-2Gminutes. The pair of diversthen swamto a differentsample site. The numberof swim kicksrequired to swimto thenew site was obtained from a randomnumbers table printed on waterproof paper. A completedescription and analysis of the samplingtechnique can be foundin Bohnsackand Bannerot986!.

Data Analysis

Data were analyzedusing Statistical Analysis Systems, Inc. software and the UNCW VAXcoinputer. Total number and mean number were calculated for eachfish species by zone. Additionalcomparisons by zoneincluded species richness mean number of species!and speciesdiversity. The Shannon-Weiner diversity index as presented in Smith974! wasused to calculatespecies diversity.

RESULTS AND DISCUSSION

Threedays of samplingresulted in a totalof 47samples with 14,18, and 15 being taken in zones1,?and 3, respectively.The averagedepth sampled in eachzone was 2.7 tn in zone 1, 5.1 m iri zone?and 7.2 m in zone 3.

Habitat Description

Zone 1 wasdominated by hardcoral, followed by limestone, gorgonia, and sand. Coral found in this zone was primarily fire coral, MNeporacomp/anna. Limestoneand sand dominatedzone 2 followedby hardcoral and gorgonia. Elkhorn coral, Acmpora pzLmata, dominatedthe hard coralsin zone2 althoughsoine smaller heads of brain coral,Monazrtrea annularis,were present. Zone 3 wasdominated by sandfollowed by hard coral,limestone, andgorgonia. Both brain and elkhorn coral were present, however, brain coral donunated by formingmassive heads at thebases of thespurs. As depthincreased the relative percentages

377 Divingfor Science..J9N

ofgorgonia decreased andthat of sand increased consistently. Theincrease insand with depth wasa resultof thepresence of the wider sand grooves between the spur formations.

FishAssemblage Eighty-eightspecies representing 27families were observed during the study period ghble1!. Fainiliescontaining themost species were the Pornacentridae, Labridae, and Haemulidaefollowed by the Scaridae and Serranidae. Forty-one species 6.6%! were observedinall three zones. Five species .7%! were observed onlyin zone 1, 10 1.3%! wereobserved only in zone 2 andeight species 9.1%! were observed only in zone 3 Table2!. Theoccurrence ofa species inoiily one zone may be attributed tothe habitat present insome cases.For example, the large percentage of sand found in zone 3 mayhave resulted in the presenceofsuch species asthe yellow stingray and bridled gaby. The short study period may alsohave resulted inthe observation ofa speciesinonly one zone. A totalof 11,996individuals were observed during the study period Table 1!. The greatestnumber of species were observed in zones 2 and3. Meanspecies richness was also highestinzones 2 and 3 withvalues of19.9 and 19.2 respectively. Mean species richness for zone1 was16.5. Species diversity forzones 1,2, and 3 was4.5, 4.3, and 4.2 respectively. This indicatesthat although more species were present in zones 2 and3, thedistribution of individualsamong species was tnore even in zone1. Tenspecies comprised 78.1% of thetotal number observed for allthree reef zones Thble3!. These species included 3 labrids, 3 pomacentrids, 2 haeinulids, 1 carangid, and1 lutjanid.Bluehead wrasse,, sergeant major, smallmouth grunt, and the bicolor damsel numeri- callydominated theSombrero Keyfish assemblage. Although their relative ranking changed, theywere thefour most abundant fishspecies throughout allthree depth zones. The feeding requirementsofthree ofthese species xnaybe less restrictive than other similar species. This mayhave resulted intheir numerical domination ofthe reef fish community. Thebluehead wrassereadily takes plankton inthe water coluimL Other labrids consume macroinvertebrates associatedwiththe substratum. Thesergeant inajor isa rnidwaterfeeding planktivore. The bicolordamsel feeds on plankton asweil as algae. Barjackwas among the ten most dominant species in all three zones. Likewise, yellowtailsnapper andbluestriped gruntwere among theten most numerous species inall threezones. The striped grunt was included inthe top ten species inzone 1 aswas the French gruntin zone 3. Thegrunts are macroinvertebrate bottomfeeders and feed off the reef at nightusing the reef for shelter during the day. Theonly other poinacentrid fishamong theten most dominant wasthe dusky damsel inzone 1.One mullid «nd 2 labridsinzone 2 and2 labrids inzone 3 roundedoutthe ten most dominantspecies in each zone. Unlike the haemulids, thespecies from these last three familiesaredependent onthe reef for food aswell as shelter andbecause ofthis a pattern seemsapparent. A herbivorous bottom feeder, the dusky damsel, inzone 1 appearstobe

378 'Aompsoner aL ReefFishes at SombreroKey, Rorida

replacedby the macroinvertebratefeeders in zones2 and3. Thealgal food source required by the duskydamsel might not be asabundant in zones2 and3.

Family Accounts

Holoeen friday

Therelative abundance of all threespecies of squirrelfish was greatest in zone3 Pebble 1!. Nocturnallyactive, these fish hover in or closeto crevices during the day fresher 1984!. Thenumerous crevices and ledges at the base of eachlimestone spur provide optimum daytime habitatfor thesespecies. Bohnsack et al.985! reportedthe holocentrids onLocc Key Reef tobe most abundant in theforereef and buttress zones. Both zones overlap in termsof depth andhabitat composition with the zone3 of this study.

Serranidae

The graysbyand harlequinbass were more abundantin zone2 liable1!. Bohnsacket al. 985! found thesespecies to be relativelyabundant in the forereefand buttresszones althoughthe highest abundance was recorded over deep live bottomhabitat.

Pomacentridae

The three most numerousdamselfishes were the sergeantmajor, bicolor damselfish, anddusky damselfish Table I!. Sergeantmajorswere most abundant in zones2and3. Bicolor damselfishwere most abundant in zones1 and3 whiledusky damselfish were most abundant in zone 1. The two chromisspecies were most abundant in zone3. YeHowtaildamse16sh were mostabundant in zones1 and2 whereasbeaugregory were moreabundant in zone2. Threespotdamselfish were about equally distributed throughout aU zones. Generally, the planktivores were more abundant in zones 2 and 3 while the strict herbivores were more abundantin zones1 and2. Theconsistent distribution of thethreespot damsel throughout all zonesmay have been a resultof itsrelatively more aggressive behavior. Bohnsack et aL 985! reportedsimilar distributions for the planktivorous species at LooeKey Reef.

Labridae

Blueheadwrasse were most abundantin zone1 Table1!. The clownand rainbow wrassewere also most abundant in zone 1. YeHowheadwrasse were most abundant in zone 2 andpuddingwife were slightly more abundant in zones2 and3. Bohnsacket aL985! reported that most of the labrids they observedwere more abundantin the lagoon rubble habitat. Althoughwe did not samplethis habitat,three species were most abundant in zone1 suggesting a preferencefor the shallowerhabitats similar to the lagoonrubble sampled by Bohnsacket al. 985!. The preferenceof the shallowerhabitat may result in a reductionin predation pressureon thesespecies.

379 Divingfor Science...1990

Scaridae Stripedparrotfish were slightly more abundant inzones 1 and2 TableI!. Therainbow andprincess pan otfishes were relatively more abundant inzone 2 TableI!. Theredtail and stoplightparrotfishes were slightly more abundant inzone 1. Redband and redfin parrotfishes weremost abundant in zones2 and3 respectively.

Haemalidae Smallmouthandbluestriped grunt were dominant inall zones Pable I!. Stripedgrunt wererelatively abundant inzone I but were notably absent inzones 2 and3. Frenchgrunt, torntate,and Spanish grunt more abundant inzone 3. Whitegrunt and caesar grunt were tnost abundantin zone2. Themost notable similarity between these results and those of Bohnsack etal. 985!is the relatively high abundance oftomtate they reported in thebuttress zone which is habitat most like our zone3.

Chaetodoatidaeand Pomacanthidae Thebutterflyfishes andangelfishes weremost abundant inzones 2 or3 TableI!. The completeabsence of thesetwo families from zone I mayhave been due to a lackof suitable forage.The butterflyfishes consume coral polyps and the angelfishes depend upon sponges. Bothfood items may have been more abundant inzones 2 and 3. Bohnsacketal. 985! reportedthese families tobe more abundant inthe buttress zone or deeper limestone habitat whichwas dominated by sponges and octocorals.

Gobiidae Theneon goby was most abundant inzone 3 TableI!. This was probably due to the largenumber ofbrain coral heads present inthat zone since this goby was observed onlyon thisspecies of coralat Sombrero Key.

Acanthuridae Doctorfishandblue tang were most abundant inzone 1 whileocean surgeon were most abundantinzone 3 Table1!.The greater abundances of2 species inzone 1 suggestsome sjtnjlaritywith those of Bohnsacket al. 985! since they found acanthurids to be more abundantinthe lagoon rubble and forereef habitats atLooe Key Reef, both relatively shallow habitats.Tilmant 984! also reported surgeon 6shes tobe numerous within the top zone of patch reefs.

380 Thompsonet aL.Reef Fishes at SombreroKey, Florida

ACKNOWLEDGEMENTS Thispaper is contribution No. 024, Center for Marine Science Research, University of North Carolinaat Wilmington.

LITERATURE CITED

Alevizon,W., R. Richardson,P. Pitts, and G. Serviss.1985. Coral zonation and patterns of community structure m Bahamianreef fishes. Bull. Mar. Sci. 36: 304-318.

Bohnsack,J. A., D. E. Harper,D. B. McClellan,D. L Sutherland,and M. W White. 1985.A resourcesurvey of fisheswithinthe Looe Key National Marine Sanctuary. NOAATech, Rep.OCRM SPDU.S. Dept. Cornrner.,NOAA,Office of Oceanand Coastal Resource Management.108 pp. Bohnsack,J. A., and S. P. Bannerot. 1986. A stationaryvisual census technique for quantita- tivelyassessing community structure of coralreef fishes. NOAA Tech. Rept. NMFS 41: 1-15.

Ogden,J. C. 1982. Fisheriesmanagement and the structureof coralreef fish communities. Pages147-159 Ig.. G.R. Huntsman,W.R. Nicholson and W.W. Fox,Jr. eds!,The BiologicalBasis for ReefFishery Management. NOAA TechnicalMemorandum NMFS-SEFC-80.

Smith,R. L 1974. Ecologyand Field Biology.Harper and Row,Pub. New York, N.Y. Thresher,R. E. 1984.Reproduction in Reef Fishes. TFH Publications, Inc. Ltd. Neptune City, NJ.

Tilmant,J. T. 1984.Reef fish. Pages 52-63. Ig. WC. Jaap ed.!,The Ecologyof the South FloridaCoral Reefs: a CommunityProfile. Fish and WildMe Service, U.S. Dept. of the Interior, Washington,D.C. FWS/OBS-82-08,MMS 84-0038. Ward,F. 1990.Florida's coral reefs are imperiled. Nat. Geogr. 178!: 114-132.

381 Divingfor Science...I990

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382 Thompsonet al: ReefFishes at SombreroKey, Rorida

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Deborah 1 fVeber LivingSeas Pavilion, EPCOT Center P.O.Box 10,000 LakeBuena Vista, FLDRIDA 32830 U.S.A.

Theswtrnmtnghabits of threespecies of carclurnbnidsharks, a tiger Galeocerdo cuvier!,a bull Carcharhinusleucas! and four brownsharks ~charhinus plumbeus!,held at TheLiving Seas Pavilion, were observed over a two yearpenod 988and1989!. All of thesharks are females with the exception of the bullshark. Alterationsin swimminghabits relative to frequently visited areas and depthsof the tank werenoted throughout a varietyof environmentalcPuutges. Changes includedthe intmhcction and removal of sharks,and the placement of a divider whichdecreased available space. Daily environmental stimuli consistedof diver anddolphin confrontation and artijicial feedingoperations. Vunughout thestudy, sharksshowed an avoidanceof the areasnear the dolphin. All the sharksswam next to the outer wail of the aquarium D&nlylit, open areas near the sharks' feedingstationwere frequented. Divers seemed to haveQtle effec on sharkhabits exceptingthe bull shark. Theintroduction of thedivider producecE no observable changesin the sharks'habits.

INTRODUCTION

Sharkslive in a veryconcealing environment and often have wide ranginghabits McKibbenand Nelson, 1986! and any study of theirbehavior is «iif6cult andpotentially expensive.It is often impossibleto determinethe stimuli that sharks encounter and hence their reactions to them. Weihs,et aL,981! statedthat captive carcharhinid sharks in a largesimulated reef area,swam in establishedpatterns. This observation was verified by ~ow andHewitt 988! whodescribed selected swim patterns of sixcaptive shark species. The largeaquarium at The LivingSeas Pavilion places few restrictionson shark movementsand allows room for artificialreef structures and a variety ~f otherma .ne]j fe Thestudy of carcharhinids inthis extremely large controlled enviro~+nt maygeld a better understandingofspatial requirements ofsharks. 'His siinulatedenviron entenabled us to Divingfor Science...1990 documentthe sharks'swimming habits in responseto additionsand subtractionsof other carcharhinids.It was also possible to document the sharks' swimming habits in responseto dailystimuli such as diver and dolphin presence, a condition which may exist in theirnatural environment,buthas never been adequately observed. Myrberg and Gruber 974! reported aggressivebehaviors tooccur between resident bonnetheads anddiver-observers. According toThompson andSpringer 961! observations havebeen made of wild dolphins driving sharks awayfrom their young. However, dolphins and sharks may feed together without apparent conflict.Gilbert, et al., 972! observedthat "swimming habits of brownsharks were not significantlyaltered by the presence of porpoises".

MATERIALS AND METHODS Thetracking of swimnung patterns spanned January 1988 through November 1989 and consistedof 492ten-minute observations 82 hourstotal!. The establishedcarcharhinid populationsince 19&6 consisted ofone female tiger shark, Gakocerdo cuvier, .4 m totallength TL!and 214 kg!, one male bull shark, Carcharhinus kucas, .4 m TLand 158 kg!, and one femalesandbar shark, Carchanbinus phcmbeas, .0 m TLand 57 kg!. Over a periodoftwo years,changes within the shark population occurred. A secondfemale sandbar shark, Brown 2,.0 mTL and 58 kg! was added in May1988. The tiger and Brown 2 wereremoved in Januaryof1989. Two fernale sandbar sharks, Browns 3 and 4 eachat2.2 m and44kg! were addedin February1989.

Thestudy was conducted inThe Living Seas Pavilion which contains 21.5 million liters ofartificial saltwater, andis cylindrical inshape: 60m indiameter and8.2 m deep see Figure 1!.Three submerged guestviewing areas are the Inner Tank Module ITM!, Tunnel 1,and Tunnel2.Although these structures could be possible barriers, the sharks had been observed crossingover them. Man-made, fiberglass coralheads, ranging in height between 0.5 tn and 7.9m, are randomly dispersed throughout theaquarium. Allthe water parameters remained constantthroughout theduration ofthe study. Temperature andsalinity varied between 24.1 ~ 0.2C and31.0~ 1 ppt,respectively. Theyear round light:dark ratio is 17:7. Forobservations, theaquarium wasdivided into eight pie shaped sections numbered 1-8in Figure 2!. Eachsection was further divided into four areas lettered A-D!, to denote increasingdistance from the ITM. It shouldbe noted that although these sections varied in size,they were based onnatural divisions inthe aquarium, andwere the most accurate wayto pinpointthe sharks' positions. Observations weretaken between thehours of 0700and 2300 frominside the ITM or in the water using scuba gear. During each observation, a single shark wasobserved forten minutes. The subject's position was plotted at 15second intervals on handheld maps. The depth ofthe subject ateach point was noted ashigh, medium, orlow, correspondingto2.7 m increments.Thepaths between each point were plotted todenote the shark'sexact swim path. Environmental stimuhsuch asdivers, feeding, etc., were recorded to categorize observations.

386 Weber: Carclmrhinid Sharks at FPCOT Center

Observationswere taken randomly,and coveredall the different conditionswhich existedin the aquarium,on a dailybasis. These conditions are the presence and absence of diversor dolphins,arid the occurrence of fish or shark feedings. The fish are hand fed a variety of seafood,from within the water. Divers perform these feedings twice a day,inorning aiid night.In additionto thesefeedings, the divers are present in theaquarium approxitnately 10 to 14hours a dayfor maintenanceand show purposes. The sharks are fed whole and cut fish, everyother day from the surface of theaquarium see shaded area of Figure1!. ThreeAtlantic Bottlenoseddolphins Tursiops truncatus! were present in theaquarium up untilFebruary 1989.Their holding pools extend off section4D asseen in Figure2. Thedolphins' play progressedto thepoint where it wasnecessary to separate thein physically froin therest of the animalsby theinstallation of a divider Figure 2! madeof PVCpipe and rope which allows smallerfish to swimthrough.

Eighty-twohours of data were collected from January 1988 through November of 1989, whichwere spread over seven different time periods Cumulative 1 Cum1!: January 1988- May1988. 1 hourscollected on three sharks!, Transition I: May 1988. Brown 2 added. hourscollected on four sharks!, Cumulative 2 Cum2!: June1988-October 1988. 8 hours collectedonfour sharks!, January 1989: First three weeks inJanuary 1989. Removal ofTiger andBrown 2. hourscollected on two sharks!, Transitiori II: January1989-February 1989. Browns3 8r.4 wereadded. hourscollected on foursharks!,' '[Before %hll, March 1989-May1989! After Wall May 1989-Noveinber1989!. Dividing wall installedbetween sections4 and5 see Figure2!. 5 hourscollected on four sharks!.After one month adjustmentperiod. 9 hourscollected on four sharks!j. Chi-square tests were performed to determinerandomness of svtimming.

RESULTS Thesharks' swimming habits were not random throughout the duration of the study x = 7.13-152.2df= 3P >0.001!. Table 1 showseach shark's preferred sections throughout theseven time periods. A preferredsection isone in wbich the subject spent greater than 10% of itstime. Random swinMiiag patterns would be reflected in 3%time spent in eachsection. Theaverage amount of timespent in eachnon-preferred section was 1.6% ~ 0.5%

387 Dnkg for Science...le%

F ~ ~ or gag}yski~ QvcFtbc cMIFsc ortlpo ~. rtlhcil @+~ t t ~ Clm I ~ ~ Wall! to represcateutque eavlreamcolal coa@tt

DEPIHS: Depthdata were analyzed usingthe three depth divisions ofHIGH, MEDIUM, tuel H!W,corresponding to2.7 m depthincrements. Comparative relative depth proflles are showninFigures 3-5.Percent timespent atdepth isgraphed asa functionofdepth foreach subjectthroughout theseven timeperiods. Theaverage amount oftime expected tobespent atone particular depth division would be 33%. Chi square tests were performed totest randomnessineach sharks depth distribution . Results arepresented inFigures 44.

DISCUSSION InCum 1,it is believed thatBrown 1 was ableto occupy section SCdue to her size wassmaller andmore rnaneuverab]e whichwould enable herto easily pass through thela'Ã coralheadoccupyingthat section. Thismaneuverability isalso reflected inher preference for MEDIUMe OJMdepth!. depthdivision during thistime as the opening inthe coralhead isat « DuringTransition I,both thetiger andthe bull changed swimming habitsslightly > ~ moretimewas spent inthe HIGH depth divisioiL Brown 1'shabits immediately changd duringTransition I,whea both preferred tanltsections anddepth levelchanged tocorresp withthe preferences ofthe nay added ~nsp~dfi~ Br~2. This immediate ch~eg ' g ' 'J~.eflect anitlterspecific relationshipof schooling, whichwould supp" thefindings ' gsof Gilbert ' aI967!eg aI andCastro 983! orit cou!d beattributed todo Gilbertet al 967! statedat th individualsofthe same sizehave been known tosc"~ Weber:C roc/garhinidSheets gr Epcor Center

in nature.~ II Castro 983! statedthat sarrdbar sshark ar "t ten d tot segregateby sex...oftenforming scnools . nngWm 4 thetiger still did not reflect any changes inswimming habits but maintaineda preference forthe HIGH depth division. This small change inhabits could have beendue to lack of space atLOW depth division. Ingeneral thetiger displayed theleast amountof changein swimming habits. Also during Curn 2, the bull shark was observed to changehispreferred sections byavoiding theone that all the other sharks occupied. A possibleexplanation could be due to the lack of space. Throughout Cum 2, Brown 1 maintaineda preference forsections anddepth divisions withor near Brown 2,again possibly due to either schoolingor dominance. In January1989, the bull did not migrate back into sectiori 8D, but remained in the sametwo sections and displayed nodepth preference. Brown 1 stillretained a preferred sectionnear ones previously occupied byBrown 2 mostofthe time, however, shedid migrate overto 7D which was occupied bythe bull. Similar tothe bull, Brown 1 alsodisplayed nodepth preference. DuringTransition II,the bull migrated back into 8D, possibly tohave more space since noother sharks occupied it. He alsopreferred the same sections as in Curn1. Thebull also developeda depthpreference for the LOWsection which was the sameas all the othersharks. Brown1 changedhabits irrunediately and preferred sections and depth divisions which were near,or occupiedby, both the newsandbars and the bull. Again it is believedthat this could be attributed to the schoolingtendency of browns,or to establishdominance. Both of the new brownstended to prefer sectionswhich were near Brown 1 andthe bulL Thosesections were alsoclear of anylarge coralheads. They also both preferred the LOW depth division.

During both time framesBefore Wall and After Wall, the bull maintainedthe same three sectionsnear the backwall, andcontinued to preferthe LOW depthdivision. Brown 1 alteredher preferredsections during Before Wall, by occupying two preferredsections which were along the outer wall. One of the preferred sectionswas occupied by the bull and the other was occupiedby the newbrown. However,through both time framesBefore Wall and After Wall, Brown 1 maintainedthe preferreddepth LOW. The newbrowns both decreased the numbersof sectionsthey preferred from four to three.It is possiblethat during Transition II, they were more spreadout in order to testdifferent areas, then afterone monththey each settledinto fewer preferredsections.

After the installation of the wall, the bull still occupied the samethree sectionsmost of thetime, as weII as the samedepth preference for LOW.Brown 1 alsopreferred the same three sectionsas the bull, andshe also maintained a preferencefor LOW. Brown3 preferred onlytwo sections, both near the outer wall and with the bull and Brown 1. Shealso maintained theLOW preference. Brown 4 preferredallthree of thesections preferred by the others and shealso preferred one additional section near the others but unoccupied bythem. This could Po»bly be attributedto lackof space.And again she also preferred LOW.

389 Diving for Science...1990

Thefindings of this studysupport those of Crow andHewitt 988! in that tiger sharks were found to prefer the upper one-thirdof the water column. Crow and Hewitt also found thatbull sharksoccupied the upper one-third of thewater column. The first year of thisstudy confirmedthose findings, however, upon the reinovalof the tiger shark,the bull preferredthe lower one-third of the water column. Crow and Hewitt also found that sandbar sharks occupiedthe lower two-thirds of thewater column. Again, those findings are confirmed by thisstudy, although more specifically, the sandbarswere observed to prefer the lower one-third of the water colunm.

Changesin swinuninghabits due to thestimuli of divers,dolphins and feedings, were recorded,however, statistical analyses have not been performed. The following are notations on the effects of those stimuli.

Whendivers non-feeding divers on conventional open-circuit SCUBA! were present in theenvironment, the tiger and the brown were generally unaffected. They seeined unaware of thedivers and it wasnot uncommon to bumpinto the sharksif the diverwas not looking. Thebull shark,however, would veer off suddenlywhen confronted by a diverin hispath.

The dolphinsin the aquariumwere extremely playful andwould vocalizeat the sharks and"shadow" them followalong beside, behind or on top!. This occurredrarely with the tigerand the bull. During these few instances the shark would react by increasing it's swimming speed.Most of tbetime the dolphins chose the sandbars for theobject of their'play'. They wouldnip at the shark'sdorsal or caudalfins. Theywould poke the sharksin the sidesand front of headwith their rostrum.Often times this would increase to the point whentbe dolphinswould end up in pinningthe shark to thebottom so that it wasmotionless. Whenever possiblethe sandbars would react by increasing their swimnung speed. The findings from this studydo not coincide with observations byThompson 961! of dolphins driving sharks away fromtheir young. In thissituation, the dolphins had no young to protectand therefore it is believedthat the dolphinswere simply 'playing'. Due to the fact that the sandbarsharks did changetheir swimming habits in thepresence of dolphins, the findings of Gilbert,Irvine and Martini972! in whichsandbar sharks were not affected by dolphins, are not supported. Thefish feedings in theaquarium seemed to haveno effect on thetiger or thebull. Thebrowns however, were attracted to theareas of fish feeding with varying intensity. Often, they seemedattracted to diverswith herring. On someoccasions the sharkswould retrieve anyherring that other animals dropped. It waspossible for thedivers to wardoff the sharks but the effectswere not longlasting. Thesharks' swimmiiig habits seemed tobe unaffected bythe installation ofthe dividing wall. Althoughthe dolphins could still see the sharks and vocalize at theinfrom the other side of thedivider, this did not seem to have an effect on the sharks swiinming habits ie. they continuedto swim nearthe divider!. Thisstudy confirmed thatcaptive sharks generally move indefinite patterns and occupy specificzones Weihs et al, 1981; Crow and Hewitt, 1988!. All ofthe sharks seemed toprefer

390 Weber: Carcharhinid Sharks at SCOT Center

sectionswhich were away from the dolphin holding areas, near the shark feeding station, and closeto theouter wall. Thesesections also tended to bemore dimly lit andclear of coralheads compared to other sections. Documentationofhow various stimuli affect sharks' swimming habits in captivity, may yieldan insightof spaceutilization of captivesharks under a varietyof conditions.With additionalstudies, a betterunderstanding of the behavior of captivesharks may be attained.

ACKNOWLEDGEMENTS I wouldlike to thankSherri Seligson forher contributions tothe first year of the study. I wouldalso like to thankA. Wangof theUniversity of CentralFlorida, M. Carroll,staff and managementof The Living Seas Pavilion for theirsupport, as well asM. Xitco andJ. Crow for their comments and criticisms.

LITERATURE CITED Castro,J. I. 1983.The sharks of NorthAmerican Waters. Texas AkM UniversityPress, CollegeStation, Texas. Crow,G. L, andJ. D. Hewitt.1988. Longevity records for tiger sharks Gakocerdo cuvier! with noteson behaviourand management.Int. Z00.Yb. 27: 237-240. Gilbert,P. W.,et al.,eds. 1967. Sharks, skates, and rays. Johns Hopkins Press, Baltimore, Maryland. Gilbert,P. W., B. Irvine,and F. H. Martini.1972. Shark porpoise behavioral interactions. MoteMarine Laboratory, 9501 Blind Pass Rd. Sarasota, Florida. 33581. 3 pp. McKibben,J.N., and D. R. Nelson. 1986. Patterns ofmovement and grouping ofgray reef sharks,Carcharhinas amblyrhynchos, at Enewetak,Marshall Islands. Bull. Mar. Sci. 38!: 89-110. MyrberqA. A.,Jr., and S. H. Gruber.1974. The behavior of thebonnethead shark, Sphyrna ttbum. Copeia. 1974:358-374. Thompson,J.R., and S. Springer. 1961. Sharks, skates, rays, and chimaeras. Publ. Dept., U.S. Fish.Wildl. Serv., Washington, D.C. circular 119, 19 pp. Weihs,D., R. S. Keyes, and D. M. Stalls. 1981. Voluntary swimming speeds oftwo species of largecarcharhinid sharks. Copeia, 1981!: 219-222.

391 Diving for Science...1990

ah~ rl reading tet.ion

ooealae 'l.i ~ his'h dolph heidi pool~ StIIII ooeala> ~. 4a hleph sharkfaediaq station

Figurel. Overheadview of 'fbe Uvtng Seas Pavilion. Shaded coruls represent those whichextend into the 'highs depth division seemain text!. Diameter= 60 m.

Figure2. Overbeadview of thcaquarium depicting labelled sections used for observations, Walls' ~ betweea sections 4 aud 5 aud aLsobetween sections 2 and 3 above 1hnnel 2! werc iustalkd May L989. Radius A-D! = 21.0 ~43 m.

392 Weber: Carcharhinid Sluvks at SCOT Center

IDD

II I m I I1oI I DD IG fhEu ~ 2 'II 1 I CD E h E

h DEI'TH DETTII

~hhhh2

DD TI h CD CD E

Il DEDTh Figurc3. Comparative relative depth profiles foethc tiger, bull, Browa t, aud Brown 2 during Cum1, %mssition I, ond Cum 2. PercenttiTnc is graphedssa functionofdepth.

DD DD ED T I 1I h DD CQ

2D D E h h h DDTTh DEFT!I Figuvc4.ComparITtfvc relativedepthprofiles forthc bai ond Broun >IdmTh2g Joannes'f pep. Percenttime is graphed asa faadionofdepth

393 Divingfor Science...1999

T00t DIIOvrlI i LDDv

l0 I 1 I I 00 0 00 L L ZD

0 0 DEPTH DEPTH

08 00 T I T I 00 0 K E ZD

0 L

FigureS. Comparativerebtiwe depth pro6les for thebalt, Brown1, Brown3, aud Brown4, during the time periodsof fiansltiou II, BeforeWail anElAtter Wall.

394 BUBBLE MODEL IMPLICATIONS FOR MULTI-DIVING

B. R. Wienke Applied Theoretical PhysicsDivisions Los Alamos National Laboratory LosAlarnos, NEW MEXICO 87545 U.S.A.

jvfulti-diving multi-level,repetitive, mLdti-day, deeper spike!, using present models, witnessesa greatershare of problemsthan both bounce and saturation diving. Part of the troublearises from incompatibletreatment of bubblesand gas nuclei Within bubblemode&, ilh areredressed through:

I! reducedno-stop time limits,based on varying-permeabilitybubble skins; ! safetystops or shallowswimming ascents! in the 10-20ft zone; ! ascentrates not exceeding60 ftlmin; ! restrictedrepetitive exposures particularly beyond 100 ft, basedon reductionin pernu'ssiblebubble excesses; ! restrictedspike shallow-to-deep!exposures based on excitation of additional micro nuclei; ! restrictedmulti-day activity based on regeneration ofgas nuclei; ! smoothcoalescence of bounce and saturation limit points, consistent with bubble experiments; 8! consistenttreatment of altitudediving; Discussionofthese pointsis the focus, with implications fordiving practice. A bnef descriptionof the reduced gradient bubble model RGBM! is given.

INTRODUCTION Validationiscentral to diving, and much testing of non-stop and saturation schedules BoycottetaL, 1908; Buhlmann, 1984;Workman, 1965;Spencer, 1976;Weathersby, 1984; YountetaL, 1976; Kunkle etal., 1983; Thalmann, 1984;Thalmann, 1986;Farm etal., 1986; Langetal., 1989; Lang etaL, 1990; Vann etal., 1989; Walder, 1968; Pilrnanis, 1976;Hills, 1977; «mplemann,1957!has transpired. Inbetween, repetitive, multi-level, deeper-spike, and multi-daydiving cannot claim the same benefits, though some programs Thalmann, 1984; Thalmann,1986!are breaking newground. Application ofthe Haldane algorithm inthe latter caseshaswitnessed higherbends statistics thanin the former one, asreported byVann VarUi «al,1989! inDAN newsletters, anddiscussed atworkshops Latigand Hamilton, 1989;Lang »dEgstrom, 1990!and technical forums. Reasons canbeconjectured, someofwhich directly impactdecompression algorithms.

395 Lh'vingfor Science...19%

TheHaldane approach Boycott etaL, 1908! isbased on a dissolvedgasmodel, and h f l th b 1kof tissue gas Ee~ inthe di~lved state, the more corre~md thereforeusefulwillso prove long such ast ean approach. u o issuButas increasing proportions offree phases Yount et~ 1976-Hennessy andHemplem~ 1977 Wie~e. 1989' Yount and Hoffm~ 1986; Yount, 1982;Yount, 1979; Yount etaL, 1979; Wienke, 1990! grow, by direct excitation ofcritical micronucleiorgradual bubble coalescing transitions, theclassical algorithm loses predictive basis.Such conditions might attend diving activity extrapolated outside model and test range~ maybeasa surprise.Thefact that some! divers push Haldane meter algorithms toiijn,t, beyondtested Haldane tables Farm etal., 1986; Lang er aL, 1989; Lang et al., 1990; Vann er aL,1989! underscores theneed for more globally applicable schemes, possibly with greater focuson free phase buildup. In lockstep, procedures such as shorter no-stop time tuni Spencer,1976! safety stops, Lang etaL, 1990; Pilmanis, 1976! and slow ascent rates Lang et al.,1989! are consistent with bubble dynamics. Though not proven, these conservative protocolshopefully lower bends incidence statistics. The problems associated with multi divingmight also be addressed through reduced repetitive gradients or equivalently,tissue tensions.While reduced gradients are very diKcult to codifyin tableframeworks, they are relativelysimple to implementin digitalmeters.

BUBBLK DYNAMICS

Bubbles,which are unstable,might grow from stable,micron size, gas nuclei which resistcollapse due to elasticskins of surface-activatedmolecules surfactants!, or possibly reductionin surfacetension at tissueinterfaces. If familiesof thesernicronuclei persist, they vary in sizeand surfactantcontent. Large pressures somewhere near 10 atm! are necessary to crushthem. Micronuclei are small enough to passthrough the pulmonaryBters, yet dense enoughnot to float to the surfacesof their environments,with which they are in both hydrostatic pressure! and diffusion gas flow! equilibrium.Compression-decompressiort is thoughtto excitethem into growth.Ordinarily, bubble skinsare permeableto gas,but can becomeirnperrneable when subjected to heftycompressions again 10 atm!, outsidenominal activity.Such a modelof skinbehavior, called the varying-permeability model VPM!,was proposedby Yount979! andStrauss, Yount et al., 1976!and extendedby Kunkleand Beckman983! andother co-workers Yount er al., 1986;Yount, 1982;Yount 1979;Yount @ al., 1979!.Rudiments of nucleationmodels can be tracedto early observationsof Waider 968!. By trackingchanges in nuclearradius that arecaused by increasingor decreasing pressure,the VpM hascorrelated quantitative descriptions of bubble-countingexperun carriedout in supersaturatedgel Yount,1982; Yount er aL, 1979!.The modelhas also been usedto tracelevels of incidenceof DCSin animalspecies such as shrimp, salmon rats ~ humans.Microscopic evidence has also been obtained which indicates the spherical gas nuc " thosepersistent microbubbles, actually do exist and possess physical properties consistent ~+ earlierassignments. For example, nuclear radii are on theorder of 1micron or less,and th + numberdensity in bio-mediadecreases exponentially withincreasing radius, characteristi« a systemVPM nuclei in equilibrium with their surroundings atthe same temperature.

396 +enke:Bubb& Model Implications for Multi-Diving

A VPMcritica} radius, rp, at fixedpressure, Pp, represents a cutoff for growth upon decompressionto lesser pressure. Nuclei larger than rp will all grow upon decompression. Additionally, following initial compression,hP =P Pp,a smal}erc}ass of micronucleiof criticalradius, r, canbe excitedinto growthwith decompression. Pib}e 1 listscritical radii, r, excitedby sealevel compressions Pp -33fsw!,assuming rp=.8 microns.Deeper decornpres- sionsexcite smaller, more stable, nuclei. Apparent}y the bodyis able to supporta certain numberof safe micronuclei,and a certainexcess for varying periods of time,decreasing with cuinulativeexposure time. Short deep dives excite inany small nuclei, while longer shallow divesexcite fewer larger nuclei. Since tissue deformation and impairment of circulationshould dependupon both the sizeand numberof bubbles,it seemsplausible that the total volume, V,nt, of evolvedgas would serveas an effective criteria in anymodel. For shorterdecompres- sion times, bubble nuclei havelittle tiine to inflate.The permissiblecritical radiusis then sma}}er,and the allowedsupersaturation larger, resulting in manysmall bubbles. Conversely, during long decompressions,bubbles may grow very large, so that only a feware permitted.

'Ihbk l. Kxdtatlou Radii

CRITICAL GRADIENTS AND NUCLEI Anyset of non-stoptime linuts can be plugged into model equations, andmaximum tensionsacross allcompartments anddepths assigned asthe M-values. Corresponding critical supersaturationgradients, 6, are obtained bysubtracting offainbient pressures, P.Using a set ofreduced time limits, listed in Table 2,we can construct a conservative setof gradients for purposesofillustration anddiscussion. Thebounce gradient, G,is computed foreach compartment,r, across the tissue spectrum, lsr~720 minutes. Non-stop exposures, with surfaceascent, thus al}ows Gpfor that compartment. BothGp and dG are tabulated inTable 3,with hG taken from Buhlrnann 984! and representing thechange incritical gradient with depth,d. Because thetime limits are conservative, thesupersaturation gradientsare a}so coriservative.Maxitnum tensions occur at threshold depths, did, for no-stop limits, ted. Whatisreflected here isthe body's ability tosupport increased degrees ofsupersatura- tioriwith increased pressure. Bubbleand micronuclei tendtoboth shrink andstabilize under pressure,permitting increased levelsof supersaturation becauseofgreater surface tension pressure.Under decompression smallerbubbles andnuclei also grow more slowly forthe

397 Divingfor Science...1990 samereason. Surface tension pressures, varying inversely asthe spherical rad;us h l l ' thepocket bysqueezing andbuilding up a diffusiongradrent across Q boundary.expe gasin Unless e pocnuclei are stabilized sothat the net surface tension iszero gl n l; eventuallycollapse upon themselves because ofthis squeeze. When nucle; ~e + increasingpressure, experiments established thatthey stabilize atnew smalle growingback to earlier size unless pressure isreduced.

I%hie2. Bounce%me Limits.

depth time limit depth . 'time limit d ifsw ! I t~ mtnutc s ! d fsw! l~ ttullQh'S!

10 1 tt40. 130 10 4tLA. 140 30 230. 1.50 7. 40 10tt. 160 50 65. 170 5.5 60 40. Ett0 5. 70 30. 190 4.5 tt0 >j 200 90 1 tt. 210 3,5 100 15. 220 3. 13. 230 2.6 L": 11. 240 ZD

Ihbte 3. Bounce Gradients.

ld depth surface gf adient gradient change tft >

192.4 819 150.0 $19 35 '93,9 $19 5

Althoughh thetheactual size distribution ofgas nuclei in humans isunknown, experiments Yount, er aL 1979! ! in vvivum suggest thata decayingexponential isreasonable. Undersuch circumstances,a largernumber ofsmaller nuclei areexcited intogrowth bydeepe«ecornp sions,and a smallernumber umberoflarger nuclei excited byshallower decomp«ssio~-

398 %ienke:Bubble Model Implications for Multi-Diving

SEPARATEDPHASE HYPOTHESIS AND MULTI-DIVING FRACTIONS Therate at which gas inflates in tissuedepends upon both permissible bubble number, ~, andsupersaturation gradient, G. Thephase volume hypothesis requires that the sum of theproduct of the twoover time must always remain less than some limit point,a Vent,with a a proportionalityconstant and V

Extending Wienke, 1990!the phasehypothesis to multi-diving,it wasshown that any conservative!set of bouncegradients, G, suchas Table 3, canbe employedfor repetitive diving, provided they are reducedat successiveexposures. Denoting the reducedset, G, we take,

G=gG, with 4 aset of multi-divingfractions bounded in relativeterms, that is,

0 sf<1. ! As repetitivetime intervals decrease, appropriate 4 should get smaller and staging approachsaturation linuts. As repetitive time intervals increase,4should getlarger, and staging approachbounce limits. In between, total elapsed time, total surface interval, tissue compartment,and profile determine g.Considering interpolating behavior, a checklist ofproperties of 4, correlatingwith divingpractice, is desirable: ! 4 equalsone for a bouncedive, but remains less than one for repetitive dives within some characteristic interval; ! 0 decreasernonotonically with increasing exposure time; ! b irlcreasemonotonically with increasing surface interval time; ! 4 scalefaster tissue compartments the most; ! 4 decreasewith depthof dive segment; ! k scaledeeper-than-previous dives the most; ! 4change withevery dive segment, butonly within anydive segment whena greater depth 8!isthe reached;time mmt t controllingg isrelated tothe regeneration timeto mcronuclei, ir,an the permissiblebubble excess, M. Consistentwith the above set, a multi-divingfraction can be constructed fromthe inverseof nuclei regeneration times,4, theexcitation raradii, ii, r, anand the e characteristiccara time constantfor permissible bubbleool excess intissues issue, M. These f are written in simplest form,

399 Divingfor Science...1990

[1-exp ~ r~r! j exp Am imp!, ! withtgggr interval surfaCe!time, t~p tOtal elapsed!repetitive time and tpmln the SmalleSt ratiO of permissiblebubble excesses on consecutivedives nevergreater than one!. Permissible excessesdepend oa 1 -r/rg3, with r givenin Table1 forvarious pressures. Every factor in Eq. ! isbounded lFzero and one. Corresponding timescales inthe exponentials arenear a minutes!and 2 r a days!.In repetitiveapplication, these 4 possesssome general properties, consistent with the above checklist:

! reducepermissible repetitive gradients; ! approachone assurface intervals grow large; ! reducemultiply permissiblegradients; ! penalizedeeper-than-previous dives; ! affectall tissuecompartments.

Both4 and ~ control repetitive diving, more particularly, the permissiblecritical teasioas,M, or critical gradients,G, and G =M-P, for P the absolutepressure, with 4 mostly affectingmulti-day and ~ mostly affectingrepetitive activities.

Thesesix parameters,g, aadEq. ! form the basisof the reducedgradient bubble model RGBM!, Wienke,1990!, presently in developmentstages in a digitalmeter. Reduced aon-stoplimits, limited repetitivegradients, safety stops, and deeper-than-previousdive scaliagare part of the algorithm.

ACKNOWLEDGEMENTS

Wethank colleagues aad friends for their help andadvice in this analysis.IadividuaIs includeTom Kunkle LANL!, David Youat University of Hawaii!, CharlesLehner and Kd Lmphier Universityof Wisconsin!,Ed Thalrnann and Jim Chimiak NEDU!, andespecially the LosAlamos National Laboratory LANL! for personalsupport.

Boycott,A. E.,Damant, G. C. C.,and Haldane, J. S. 1908. ThePrevention Of Compressed- Air Illness",J. Hyg. 8: 342M3. Buhlmana,A. A. 1984."Decompression/Decompression Sickness", Berlia, Springer-Verlag. Farm,F. P., Hayashi, E. M., andBeckmaa, E. L 1986."Diving And Decompression Sickness TreatmentPractices Among Hawaii'sDiving Fisherman". Universityof Hawaii Sea GrantReport UNIHI-SEAGRPK'-TP-86-01, Honolulu. Wienke: BubbleModel I nplicationsfor Multi-Diving

Hemplernan,H. V. 1957."Further Basic Facts On Decompression Sickness", Investigation Into The DecompressionTables. Medical Research Council Report, UPS 168, London. Hennessy,T. R., andHempleman, H. V. 1977."An ExaminationOf The CriticalReleased GasConcept In DecompressionSickness". Proc. Roy. Soc. London B, 197:299-313. Hills, B. A. 1977."Decompression Sickness". New York, John Wiley And Sonslnc. Kunkle,T. D., andBeckrnan, E. L 1983. "BubbleDissolution Physics And The Treatment Of DecompressionSickness". Med. Phys. 10: 184-190. Lang,M. A., and Egstrom, G. H. 1990."Proceedings OfThe American Academy OfUnder- water SciencesBiornechanics Of SafeAsceirts Workshop". Diving SafetyPublication AAUSDSP-BSA-01-90,Costa Mesa. Lang,M. A., and Hamilton, R.W. 1989."Proceedings OfThe American Academy Of UnderwaterSciences Dive Computer Workshop". University Of SouthernCalifornia SeaGrant Publication, USCSG-TR-01-89, Los Angeles. Pilrnanis,A.A. 1976. "Intravenous GasEmboli In Man After Compressed AirOcean Diving". OfficeOf NavalResearch Contract Report, N00014-67-A-0269-0026, Washington, D.C. Spencer,M.P. 1976. "Decompression LimitsFor Compressed AirDetermined ByUltrasoni- callyDetected Blood Bubbles". J.Appl. Physiol. 40: 229-235. Thalmann,E.D. 1984."Phase II Testing OfDecompression Algorithms ForUse In The US NavyUnderwater Decompression Computer". USNExperimental DivingUnit Report,NEDU 1-84, Panama City. Thalmann,E.D. 1986."Air-¹02 Decompression Computer Development". USNavy ExperimentalDiving Unit Report, NEDU 8-85, Panama City, Vann,R.D., Dovenbarger, J.,Wachholz, C.,and Bennett, P.B.1989. "Decompression Sickness InDive Computer And Table Use", DAN Newsletter, 3-6. Walder,D,N. 1968. "Adaptation ToDecompression SicknessInCaisson Work". Biometeor. 11: 350-359. Weathersby,P.K., Horner, L D.,and Flynn, E.T. 1984. "OnThe Likelihood OfDecompres- sionSickness. J.Appl. Physiol. 57: 815-825. Wienie,B.R, 1989. 'Tissue GasExchange ModelsAnd Decompression Computations:A Review".Undersea Biomed. Res. 16: 53-89. Wienke,8.R. 1990. "Reduced GradientBubble Model". Int.J.Bio-Med. Comp. in press!.

401 Divingfor Science...I 9W

Workman, R, D. 1965. "Calculation of DecompressionSchedules For Nitrogen-Oxygen and Helium-OxygenDives", USN ExperimentalDiving Unit ResearchReport, NEDU 6-65,Washington, D.C.

Yount,D. E. 1979. "SkinsOf VaryingPermeability: A Stabilization MechanismFor Gas Cavitation Nuclei". J. Acoust. Soc. Am. 65: 1431-1439.

Yount,D. E. 1982."On The Evolution,Generation, And RegenerationOf Gas Cavitation Nuclei", J. Acoust. Soc. Am. 71: 1473-1481.

Yount, D. E., and Hoffrnan, D. C. 1986. "On The Use Of A Bubble Formation Model To Calculate Diving Ptbles". Aviat. SpaceEnviron. Med. 57: 149-156.

Yount, D. E., and Strauss,R. H. 1976. "Bubble Formation In Gelatin: A Model For DecompressionSickness". J. Appl. Phys. 47: 5081-5089.

Yount, D. E., Yeung, C. M., and Ingle, F. W. 1979. "Determination Of The Radii Of Gas Cavitation Nuclei By Filtering Gelatin". J. Acoust. Soc. Am. 65: 1440-1450. AN OVERVIEW OF TECHNOLOGICAL APPROACHES TO DEEP WATER RESEARCH AT WARM MINERAL SPRINGS 85019!

Lewis M Wood WarmMineral Springs Archaeological Research Project Departmentof Anthropology Florida StateUniversity 121-35 Dorado Drive WarmMineral Springs, FLQRIDA 34287U. S.A.

Research,under the directt'on ofWilburn A. CockreN,atthe Warm Mineral Spri ngs site 8Sol9! over the last two decades has expanded thefrontier of underwater archaeologyinto depths considered to be well within extreme exposure limits. Krcavationofdeposits locatedin a cone of debris atthe bottom ofthe Springs has requiredworking dives to depths ofthirty-eight tofi fty-five meters 24-l80 FSW! withexcursions down to seventymeters 30 FSW!. Currentresearch derrutruIs have prompted the adoption of more technologically advanceddiving equipment, training, and on-sitefacilities. 7herecent addition of a fifty-fourinch,double lock recompression chamber staffed byafidl-time operator andthe use of alternate breathing gases for working dives and decompression has provento beinvaluable byincreasing bottom times and decreasing in-water decompressiontimes, while maintaining a high standard ofparticipant safety. Furthermore,the recompressionchamber offers the alternativeof surface decompression.Likewise, other curreru diving technology being used in lhecom- mercialdiving industry, including the use of remotely operated vehicles ROV's!, wasexami ned with an eye toward choosing those technologicalinnovations which hadthe greatest potential for successfid utilization in the deeply submerged anaerobicenvironmeru' of Warm Mineral Springs

INTRODUCTION Duringthe last decade, thefocus ofunderwater archaeology beganto shift towards the examinationofdeeply submerged cultural resources onthe Outer Continental Shelf as well asin lakes, springs, and sinkholes. This changing focus has made it essential thatdiving scientistsrecognize theneed for the adoption ofmore advanced diving technology toinsure notonly the success ofthe proposed work, but the safety ofthe diving scientist himself. Sincethe earliest stages ofresearch atWarm Mineral Springs in 1972, its principal investigator,Wilburn A.Cockrell, recognized theneed for reliance onmore advanced teck-

4G3 Divingfor Science...1990

nologyto satisfythe ever increasingdemands of his researchdesign. The environmentally harshwaters of WarmMineral Springsbecame the testingground for the developmentof new technologyand the adaptationof techniquesand equipmentavailable froin other areasof the divingcommunity.

Beginningin 1972,Cockrell, assisted at first by his colleagueLarry Murphy and later by the author,instituted a multi-disciplinaryeffort that hasgained world-wide recognition as havingremained at the forefrontof innovationand adaptation in the fieldsof archaeologyand applieddiving technology.Underway for nearlynineteen years now, the researchhas been conductedin two distinctphases. Likewise, any overview of the technologyutilized shouldbe viewedin the sameway.

Researchefforts during Phase I 972-1983!were conducted under the auspicesof the Florida Departmentof State'sDivision of Archives,History, and Records Management. During sixconsecutive field seasons,Cockrell inobilized large crews and launchedsuccessful, large-scalearchaeological field projects. Theseinitial efforts resultedin the explorationand mappingof the upper, shallowportion of the Springsand the excavationof an intentional 10,300yearold NativeAmerican burial on the thirteenineter ledge,as well asthe articulated remainsof extinct Pleistocenemegafauna Cockrell and Murphy 1978!. Although some exploratorydives were made to depthsof up to seventymeters, the principal researchfocus remainedthe upper nineteenmeters of the Springs.

In 1978,the activeportion of the researchwas phased out due to funding cuts and a lack of supportfrom the Florida Departmentof State,which beganto shift its efforts away from prehistoricsites and towardthe preservationof historic structures.A subsequent elimination of the Underwater Research Section of the Division of Archives forced Cockrell to seekalternate funding sources. Phase II beganin March,1983, and continues to dateunder the auspicesof the WarmMineral Springs Archaeological Research Project and is funded through the Florida State University Departmentof Anthropology by the Florida State Legislature.

PhaseII is currently the only full-time underwaterarchaeological research project in theworld and has seen the extension of workareas in theSprings into depthsbetween thirty-six andfifty-five meters.Work in this areahas only begun to revealthe mysteriesof thepast which lie entoinbedin the coinpactedsediments of a coneof debristhirty-four meters high at the bottomof the Springs.

The techniquesand proceduresapplied during these two phasesrepresent vastly differentapproaches and must be consideredin termsof the researchgoals they attemptedto satisfy,as weil as the innovations in the fieldof underwaterarchaeology they represented. Wood:Approaches to Deep Water Research at %MS

PhaseI 972-1983! PhaseI sawthe introductionof the first underwaterarchaeological field school. Conductedunder the direction of CockreH, this field school taught students from the Depart- mentof Anthropologyat Florida State University the principles of doing archaeological excavationsunderwater with thesame controls recognized as standards by terrestrialar- chaeologists.A strict, well documented divingprogram resulted ina successfulprogram which hadno incidence of decoinpression sickness or related hyperbaric trauma. The key to this successwas a setof day-to-day diving procedures outlined by Murphy 978!. Initialefforts in PhaseI werecarried out utilizing what was then considered to be "state-of-the-art"sportdiving equipment. It soon became apparent that this equipnient had tobe reevaluated andadapted tomake it inore effective inthe environment inwhich it was beingused. Of immediate concern wasthe fact that much ofthe Springs represented a partial overheaddiving environment. Thisfact, coupled with the realization thatthe fragile sediinents foundin WarmMineral Springs required special buoyancy control by divers, revealed a need toinvestigate alternate diving technology thatcould be more field proficient and more site specificallyadaptable. LarryMurphy, then functioning asProject Dive Officer, was an early proponent of techniquesdeveloped through theefforts ofthe membership ofthe National Association For CaveDiving NACD!. He recognized thevalue of their specialized diving equipment interms ofthe safety and control it affordedthe working diver. Beginning with buoyancy coinpensator modificationsto facilitate more precise buoyancy control and extending into the use of redundantlife-support equipment toincrease overall diver safety inoverhead diving environ- inents,Murphy incorporated these innovative techniques intothe day-to-day diving procedures.The close of activityin 1983saw the application ofother equipment and technology attributableto theNACD and the cave diving community, including dual high pressure orifice tankvalves and the use of redundantSCUBA regulators and arti6cial light sources Exley, 1981! WarmMineral Springs was also the site of the first use of underwater video to document excavationprocedures and to mapsignificant archaeo!oy'cal features. Beyond documenta- tion,the utilization of video,coupied with hardline voice communication to the surface, allowedparticipation inactual excavations bynon-diving scientists who, otherwise, would have beeneliminated from participating inthe research effort due to health reasons orlack of diving credentials. Whilethe focus of PhaseI continuedto bethe shallow ledges of WarmMineral Springs, decompressionprocedures became crucial aslong periods oftime began tobe spent working theseareas. To facilitate faster and inore complete scrubbing of excessnitrogen from the tissuesofdecompressing divers,medical oxygen was breathed atthe twenty foot and ten foot stops,marking a sharp departure from diver training available atthe time, which disdained the in-wateruse of oxygen. The adoption ofthis one innovative technique paid off in terms of the Divingfor Science...1090

nuinberof safedives made by staff divers without the incidence ofdecompression sickness or relatedhyperbaric maladies. The net result of an increased number of safe working dives is theincreased amount of datarecovered due to thelarge nuinber of in-waterbours accumulated andthe lack of anyhours of worktime lost due to injury. Researchended in 1977,but Cockrell continued tovisit Warm Mineral Springs on his owntime to insurethat the site was still protectedagainst looting and preserved in its undisturbedstate for futureassessment and study. During these short duration visits to the site,Cockrell continued to use the diving technology developed during Phase I Cockrell, personalconununication, 1984!. Through 1983 and 1984, Cockrell worked, sometimes using thelast of his personal funds, to get the work at Warm Mineral Springs back on track. In 1984, hesucceeded ingetting the Florida State Legislature tofund Phase II with the help of state SenatorBob Johnson and Barbara O'Horo Benton, the current Project Manager ofthe Warm MineralSprings Archaeological Research Project.

PhaseII 984 to thepresent!

Initialefforts during Phase II weredirected toward cleaning accuinulated sand from thethirteen meter ledge and reestablishing mapping points. Divingoperations were hamperedbylimited funding, a small over-worked diving staff, and "hand-me-down" diving equipment.Nevertheless, theprojected goals for the 1984-1985 fiscalyear were accomplished andstaff members were able to begin the tedious task of working toward more ainbitious goals forforthcoming field seasons, namely the coring and establishment ofdeep excavation units in thedebris cone at the bottom of theSprings Cockrell, 1986!. PhaseII saw the aforementioned extension ofwork areas into depths between thirty-six andfifty ineters. With diver safety inmind, the same technology utilized so successfully during PhaseI was applied again, only this time the principle of redundancy wascarried still further toinclude redundant buoyancy control devices, redundant primary light sources, and alternate airsupplies. Working at depth,well beyond the reach of ambient light from the surface and oftenwith limited visibility due to suspended particulates inthe water, the added safety factor affordedbythese redundancies couldnot be underestimated. Shortof a primaryairsupply failure,each diver was capable ofself-rescue andthe handling ofmost immediate equipment relatedeinergencies independently Exley 1981!. Duringthe early efforts to establish an excavation uiiit ata depthof forty-six meters orithe slope of the debris cone at the bottom of the Springs, it became apparent that staff divers werepushing open-circuit SCUBA to its maximum potential. Bottom times were limited by theamount ofair a divercould carry on his back for use during the dive, as well as during the lengthyperiods of decompression which resulted from working at depth. Therefore, research intoincreasingly more technologically advanced diving techniques began. Ofcourse,, among the first questions asked were the all important ones. How do we shopfor newtechnology? What criteria must be met to makeresponsible choices? Ar- Wood:Approaches to Deeptearer Research at WMS chaeologistsare notoriousfor their attractionfor new toys andother gadgets,but four strict basic considerations were considered.

First to be consideredwas the questionof whether the technologybeing considered wasgoing to requirethe participation of moreindividuals than were available for itssuccessful utilization. With a perpetuallylimited staff,the technologychosen would haveto requireonly a few handsto operate.

Secondly,there were the everpresent financial woes to consider. Wouldthe costof utilizing specific advancedtechnology exceed budget limitations and would the increased safetyand datajustify the cost?

Thirdly, the trainingaspect was considered. Could the Projectbear the lost downtime and expenseto train personnelto an acceptablelevel of proficiency?

Fourth, was the physiologicaland liability question. Would the intendeduse of the proposedtechnology reduce the amountof time diving personnelwould be exposedto the hyperbaricenvironment? If not, did it contributepositively to safetyor lend itself towardtask overloading,creating a riskbenefit concern?

Needlessto say,there was a vastarray of technologicallyadvanced and innovative equipmentavailable. Following a literaturesearch by the staff,numerous inquiries were sent out to a widespectrum of divingexperts and consultants,seeking baseline data on what kind of equipmentwas available and who wasavailable to providethe necessarytraining in its use. Whereonce the staff hadborrowed heavily from the cavediving conununity, they now found that the mostproductive area in whichto look for newtechniques and technologywas in the oil fieldsof the Gulf of Mexicoand the North Sea.It wasa logicalsolution to beginseeking our answersamongst the time-testedequipment of the commercialdiving industry.

Our first stepinto the future of scientificdiving wasa verybasic one. Basedupon researchperformed by the Project Manager,Barbara O'Horo Benton, and the author, a cominitinentwas made to purchasesurface-air-supplied diving equipment. A compact,diving controlconsole inanufactured by DivingSystems International and designated the DCS I, was purchasedfollowing in-water testingand evaluationby staff members. This equipinent, coupled with three-hundred foot uinbilicals and two different configurationsof diver headgear,allowed divers to havean unlimited air supplyand instantcontact with the surface by meansof hardlineradio communications or line-puIIsignals Larn andWhistler 1984!. The equipmentchosen represents the standardof the cotnmercialdiving industry and hasproven to be both durableand highly reliable. Trainingin its usewas provided by outsideconsultants who cameon-site and provided both classroom and in-water sessions. Although the useof this equipmentrequired some additional personnel to handleline tendingand consoleoperation, it provedto be field proficient andproject specifically adaptable. These advantages far out- weighedthe useof closed-circuitrebreathers or other more exoticequipment alternatives. Divingfor Seance...1996

Oneoverriding factor in choosing technology todo underwater research ata sitelike WarmMineral Springs isits depth and the concurrent problems associated withworking at depth.Asdiving scientists, wehave long been aware ofthe dangers inherent indeep diving, namelytheincreased possibility ofdecompression sickness DCS!, the debilitating effects of nitrogennarcosis, andthe increased timeit takesfor a divertoreach the surface inthe event ofa life-supportfailure.The purchase ofsurface-air-supplied divingequipment wasa stepin theright direction, but it did not addressthese concerns. Throughoutthehistory ofthe Warm Mineral Springs research,a heavyemphasis has beenplaced upon diver safety andaccident prevention. Furthermore, closeattention waspaid toemergency evacuation procedures fortreatment of hyperbaric incidents requiring recornpression.Beginning with the 1985-1986 fiscal year, monies were allocated for the purchaseofan on-site, fifty-four inch, double lock recornpression chamberand a lowpressure compressortosupport it. Thepurchase ofthese vital pieces of equipmentwasdelayed approximatelytwenty-six months, byquestions ofliability, waivers, insurance coverage, and thepotential forlitigation should anymisuse ofthe chamber result inthe compounding ofa hyperbaricinjury.These questions wereeffectively resolved bychanging theadministrating institutionunderwhose auspices theProject operated, froma localconununity college tothe DepartmentofAnthropology atFlorida State University. September 1987saw the arrival of theaforementioned chamberon site. Unfortunately, complications withfunding severely restrictedProject spending during the remainder ofthe 1987-1988 fiscalyear and no funds wereavailable toget the chamber plumbed, staffed, and operational. Duringthis time period, diving operations were also stalled due to the time it tookto integratefullyinto the Academic Diving Program atFlorida State University. Placement into tbeAcadenuc Diving Program required that all Project dives be performed under their administrativecontroland had toadhere tothe policies andprocedures administered bytheir AmericanAcademy of Underwater Sciences-sanctioned DiveControl Board, The result of havingtointegrate intoa newsystem, including testing and training, wasa fivemonth loss of in-watertime. Furthermore, theAcademic Diving Program imposed a series ofdepth cer- tificationlimitations upondiving operations whichcurtailed alldeep diving operations and completelychanged the course of thenext two years' research. Deepdiving operations began toget back on track in March, 1989, when staff members attendeda workshop sponsored jointlyby FSU and the Warm Mineral Springs Archaeological ResearchProject dealing withthe theory and hardware ofusing mixed-gas divingtechniques inscientific diving operations. Ithad long been proposed thatthe only way tocontinu.e deep excavationsatthe Springs was to incorporate alternate breathing gases into our system Benton,1988!. The five day workshop atthe FSU Marine Lab near Tallahassee, FI, introducedstat members tomixed-gas theory inthe classroom andoffered each class member theopportunity toactually mixtwo different diving gases andtest them innearby ViMrulla Springs 8%a24!. Following tbecompletion ofthis workshop, Cockrell andBenton began to workclosely with Dr. Bill Hamilton ofHamilton Research, Ltd.to develop a nuxed-gas programspecifica0y forthe Warm Mineral Springs site. This collaboration resulted ina series oftables which rely upon the use of a threepart gas mixture, referred toas trimix, which uses Wood: Approachesto Deep WaterResearch at WMS

21% oxygen,40% helium,and the balancenitrogen. An oxygenenriched air mixture, nitrox, 50% oxygenand 50% nitrogen,was suggestedfor use during the intermediateportion of decompression,followed by the useof pure oxygenduring the last two decompressionstops at twentyand ten feet Hainilton, 1989;Hanulton, Cockrell, and Stanton,1990!

Hamiltonwas quick to point out that the conceptof utilizing mixed-gaseswas not a new one. Researchinto the useof helium-oxygennuxtures for divingbegan in 1919with the work of Elihu Thomson and the United States Bureau of Mines and has becoine a standard for both military andcivilian divingoperations. Today, research continiies to be donethroughout the world regarding the use of other alternate breathinggases including a hydrogen-oxygen mixture,hydrox Chandler,1987!. Continuedresearch into theseexotic gas mixtures should providea frameworkof accumulateddata upon which a trainingprogram could be developed to providefuture archaeologistsand other divingscientists with the necessaryskills to function safelyat depth on or beyondthe limits of the ContinentalShelf and in remote recessesof karstic caves,sinkholes, and ~~

Oncea breathingmixture was chosen, tbe naturalprogression was to begingathering the necessarystaff andsupplies to beginbuilding a life-supportsystem ia whichto usethe gas. The first steptaken was to find a ProjectDiving Officerwho possessedthe skillsto build such a systemand a seriesof consultantswho could providethe staffwith addedexpertise and the training necessaryto bring staff meinbersup to anacceptable level of performancein the use of the hardware.In addition,two technicians,one full-time andone part-time, were added to the staff.

The first task undertakenwas the plumbingof the recompressionchamber and the compressor.Due to site constraiiitsand concernsover the noiseresulting from chainber operation,the compressorbad to be locatedin a spotremote Born the chamber.Problems with distanceand line losswere calculated and appropriatehose and fittings were purchased. Since the compressorneeded to be marmedduring all chamberruns, and the distance prohibited direct cominunicationsbetween the chamber operator and the compressor operator, Motorola FM hand-heldradios were purchased. As the systemwas built and problems or questions arose,viable solutions were achievedor the whole systemwas reevaluatedand an entirelydifferent tack wastaken to movearound problem areas. In this way,project-specific adaptations were made

Sixteenhigh pressurecompressed air cylinderswere addedand manifoldedtogether into two separateeight tank banksto provide a sufficientquantity of air to ru.nthe chamber through two separateTable 6A treatinent runs in caseof a power failure or low pressure coinpressormalfunction U.S.Navy,1989!. Oxygenis providedto the decoinpressingdiver througha ScottBIB systeminside the chamber.These facilitate decompression using oxygen, without the dangerof oxygenbuildup in the chamberatmosphere. Exhaled oxygen and other respiratorywaste products are removedfrom the chamberthrough an overboarddump controlled by a Tescornregulator. Me level of oxygenin the ambient atmospherein the chainberis monitored coxistantlyby an oxygenanalyzer mounted outside the chamberand plumbedto a through-hullfitting. Gasis diffusedthroughout the chamberthrough handmade Divingfor Science...1990

copperdiffuser tubes mounted oninlet fittings inboth the inner and outer locks. Supply tothe chambercanbe controlled frointhe inside toprovide additional safety for divers being compressed. Oncethe chamber wascompleted, workwas begun onthe actual mixed-gas system. Theheart ofthe system remained theDCS I console purchased in1986 for surface-air-supplied diving,butwith basic modifications topermit the manifolding oftriinix, nitrox, oxygen, and coinpressedairthrough itsreducing valve and into the umbilicals leading tothe divers. 'Ihe manifoldinginquestion was fabricated andremains anadd-on which coimects twoon-line cylindersoftrimix, two standby cylinders oftrimix, two cylinders ofnitrox, two cylinders of oxygen,andtwo cylinders ofcompressed airto the DCS I. The manifold provides forisolation ofindividual cylinders. Soinemodifications weremade tothe DCS I to facilitate aneinergency compressedairbypass ofthe main reducer valve and the entire system hasbeen cleaned for oxygenservice. Initialdives were made utilizing two types ofheadgear. Cockrell tried the commercial divingindustry's standard, theSuper-Lite 17,manufactured byDiving Systems InternationaL Althougha high quality piece ofequipment, theSuper-Lite 17'ssize and weight didnot lend themselvestothe bent over, head down posture required during archaeological excavation. Additionalproduct research revealed theavailability ofthe AGA MkII diving mask, manufac- turedby Interspiro, which featured a positive pressure seal and excellent conununications capabilities.'Nesefeatures, coupled withits light weight andeasy breathing quality, made it anobvious choice foruse by Cockrell. Other staff divers found the Heliox-18A bandmask by DivingSystems International theirheadgear ofchoice forboth working andstandby tasks. Incuinbentinthe use ofany breathing nuxwhich utilizes helium isthe problem ofbody heatloss through respiration. Tocombat thisproblem, Cockrell wassupplied witha high qualitymembrane diysuit and insulating coveralls inadeof Thinsulate manufactured byDUI UnlimitedInternational, Ltd..This suit provides adequate insulation toprevent hypotherinia. Beforeanyactual diving operations wereundertaken, extensive training programs were conductedon-site. The Project Diving Officer scheduled andcarried out numerous unmanned trainingdives inthe chamber. Staff members were taught how to conduct actual treatments basedupon U.S. Navy Recornpression Treatment Tables U.S. Navy 1989!. While these scheduledrunswere being carried out,review classes oninixed-gas theoryand diving physiol- ogywere presented on-site by Dr. Dudley Crosson of Delta P. Alongwith these classes in theorycame two pool sessions which stressed theuse of the Super-Lite 17helmet and the new DUIdrysuit. Emergency procedures werecovered extensively andbailing outof the headgear intoregular SCUBA waspracticed untilall staff divers feltcomfortable withthe techniques. Practiceinthe controlled environment ofthe pool allowed these critical techniques tobe practicedincomfort andrelative safety toinsure that if anemergency should occur, thediver wouldbe able to take the necessary action instinctively andwithout hesitation. Oncethe systein construction, testing, and training was completed, it was time to make thefirst working dive. On February 21,1990, Wilburn Cockrell donned hisAGA MKI mask

410 Wood:Approaches to DeepWater Research at WMS and madethe world's first scientificdive to do archaeologicalresearch on trimix. The divewas to a maximumof 17.98meters or 159FSW for twenty-nineminutes. The divewas performed without incident and inarked the beginningof a newtechnological era for underwaterarchaeology.

At thetime of thiswriting, theHamilton Tables have proven to behighly reliable. There has been no incidenceof hyperbaricproblems. Daily testingof the diver for intravascular bubblesutilizing a Doppler UltrasonicMonitor hasbeen performed. In this test, a highly sensitivetransducer is utilized to monitor three sitesfor bubble sounds,namely the precordium and each of the subclavianveins. A pre-dive test is done to obtain a referencereading. Followingthe dive, a postdive checkis madeat twentyininutes after surfacing and then again at a one hour interval. Three parameters are used to describe these intravascular bubbles, including frequency,duration, and percentage.These three parametersare combinedto determinea finalamplitude and then a finalbubble grade which is compared against a standard developedby the Defenseand Civil Instituteof EnvironmentalMedicine in Canada Eatock andNishi 1986!.

Doppler testingand the gradingof intravascularbubbles has traditionally been used to evaluateexperimental decompression profiles. At ~ Mineral Springs,divers are using provisionalHamilton tablesthat are calculatedspecifically for that diving environmentand their usethere representsa testingphase for thosespecific tables. The Dopplertests provide Hamilton with sufficient data for evaluation of his calculations and an opportunity to head off anythreat of DCSby recognizingthe threat through an inordinate amourit ofbubbles following workingdives.

A cooperativeeffort betweenHamilton, Benton,the ProjectDiving Of6cer,and Dr. William Kepper of the AcademicDiving Program'sDive Control Board,produced a cotn- prehensiveprotocol to dealwith the possibilityof routine decompressionsickness. This plan includesactual treatment protocol aswell asa calllist for medicaland physiologicalconsult- ation and proceduresfor dealingwith administrativematters. Staffmembers are equipped with telephonepagers to assurenotification and recallof all staKmembers in the event of a hyperbaricincident.

With an eye toward easingthe existingadministrative, logistical, and physiological concernswith making repeated dives to perform researchtasks, efforts into acquiring a remotely operatedvehicle ROV! werebegun iti 1988. In recentyears, the oil industryhas begunto seethe value of utilizing machinesto do inspectiontasks which do not require a diver's direct participation. In fact, industrysources indicate that the demandfor ROV's is currently exceedingthe rate of their production Busby,1988!. The acceptanceof their use hasbecome so widespread that NOAA hasbegun a seriesof feasibilitystudies to determine whetherROV's can be usedto performobstructioii detection and classification when evaluat- ing safepassages and the maximumsafe depths of channels Ryther, Harris, and Fish, 1990!. As of this writing, atteinpts are underway to use a tethered remotely operated vehicle to investigatethe remainsof what is believedto be a seventeenth-centurytreasure galleon in

411 Lbvingfor Science...1990

four-hundredandfifty-seven meters ofsea water some seventy-five milessouthwest ofthe FloridaKeys LeMoyne,1990!. Althoughseveral different ROV's were considered foruse at Warm Mineral Springs, thePhantom 300,inanufactured byDeep Ocean Engineering, waschosen following on-sile trainingand testing. It demonstrated remarkable maneuverability andhandling charac- teristics,aswell as high quality optics and videographic capabilities. Although itspurchase pricerepresents a high initial investment offunds, this ROV represents a cost effective alternativetothe use ofstaff divers forcertain diver tasks since ROV's arenot subject tothe physiologicallimitationsof human divers. Bottom timeis limited only by the availability ofa powersource and a trainedoperator. An ROV requires nogas supply and reduces on-site timesince thevehicle requires nolengthy periods ofdecompression. Furthermore, initial testingofthe Phantom 300atWarm Mineral Springs indicates thatits operation requires only a minimalstaffcommitment anda shortterm training period for personnel. Somecritics inthe oil industry argue that divers aresuperior toROV's for tasks which requirecomplete visualinformation tofacilitate thecompletion ofcomplex tasks Chandler, 1988!.Theexcavation ofdelicate prehistoric siteswould certainly fallinto this category since excavationtnustconstantly undergo reevaluation asactual excavation continues. The shortcomingofthe ROV may beits built-in tunnel vision and its inability totransmit observer generatedcues Allgood, 1988!. This would certainly affect the aforementioned evaluation processandaffect the archaeologist/ROV operator'sability to"read" the situation andmake corrections,resulting inlost or unrecoverable data.Nevertheless, thevalue ofROV's cannot beunderestimated. Weanticipate that the ROV canbe utilized fornumerous tasks,including thedeployment oftelevision camerasfor the inspection ofdeep excavation unitsbynon-diving contributingscientistsand the deployment ofremote sensing devices designed todo mapping andmeasure watertemperature, pH,conductivity, anda host ofother research parameters. Inan attempt tomaintain a progressive divertraining policy for staff divers, the 1989-1990fiscalyear saw the participation ofstaff divers ina trainingprogram conducted by ParkerTurner ofthe National Association forCave Diving and FSU's Academic Diving Program.Aimedat fulfilling theimmediate concernof the American Academy ofUnderwater Sciences AAUS! that research scientists working inan overhead environment shouldbe certifiedtodo so, WMSARP divers pursued their cave diving certification. Theclass also introducedthedivers tonew techniques whichare standards inthe current cavediving communityandsharpened their overall diving skills.

SUMMARY Thereappears tobe no limit to the technology beingdeveloped toaccomplish under- watertasks safely and e8iciently. Thesuccess andsafety ofthe research effort at Warm Mineral Springshasdemonstrated theneed for the underwater archaeologist tostay abreast afthe developmentsandto recognize thatthis technology canbe adapted andutilized todo

412 Wood:Approaches toDeep W'ater Research at MfS site-specificarchaeological tasksthat insure the maximization ofdata recovery while minimiz- ingthe riskto divingpersonnel. Thefuture success of theWarm Mineral Springs Archaeological Research Project and researchatother similar deeply submerged archaeological sites will depend entirely upon our willingnesstobe innovative andto embrace, nay,demand more complex, applicable technol- ogyto meet the demands ofthis increasingly demanding fieldof scientific investigation.

LITERATURE CITED Allgood,R. L 1988."Underwater Viewing Systems-Why AreWe Never Satisfied?". Under- waterTechnology: Journal for the Society for Underwater Technalogy. Vol.14, No.l.

Benton,B. O'H. 1988.Personal communication, January. Busby,F. 1988."Looking For The 'Silver Linings' In UnderseaVehicle Markets." Sea Technology.Vol.29, No.l. Chandler,K.E. 1987."Diving Deeper On Hydrogen". SeaTechnology. Vol.28, No.9. 1988."Competiiig With ROV's-Win Some, Lose Some". Sea Technology. Vol.29, No.12. Cockrell,W. A. 1984.Personal Cominunication, December. 1986.The Warm Mineral Springs Archaeological Research Project: Current Researchand Technological Applications. Diving ForScience...'86. Proceedings ofthe AmericanAcademy of UnderwaterScieiices. AAUS, Costa Mesa. Cockrell,W. A. andL Murphy.1978. Pleistocene Man in Florida. Archaeology ofEastern WorthAmerica No.6 Summer! Eatock,B. C. and R. Y. Nishi. 1986. Procedures ForDoppler Ultrasonic Monitoring OfDivers For Intravasctdar Bubbles.DCEIM No.86-C-25. Exley,S. 1981.Basic Cave Diving A BluepnntForSurvival. National Speleological Society, CaveDiving Section. Hamilton,R. W. 1989.Decompression Tables For $Varrn Mineral Springs Archaeological ResearchProject. Hamilton Research Ltd., Tarrytown, N.Y.. Hamilton,R. W.,W. A. Cockrell,and G. Stanton.1990. Using7he UHMS Validation workshopGuide&es ToSet Up A TiirnixDiving Program For Archaeological Research. Abstractin press.1990 Joint Meeting on Diving and Hyperbaric Medicine, Amster- dam.

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Wrn,R. and R. Whistler. 1984. Commercial Diving Manual. David and Charles, London- LeMoyne,J. 1990."ingot Shows Wreck May Be Galleon Filled With Gold". 5~a Herald-Tribune,June 17. Murphy,L 1978. Specialized Methodological, Technological, andPhysiological Approaches ToDeep Water Excavations OfA Prehistoric SiteAt Warm Mineral Spriap, Florida.Pmceedingsof theNinth Conference OnUnderwater Archaeology TexasAattq- uitiesCommission Publication, No. 6. Ryther,J.H., D. B. Harris, and J. P. Fish. 1990. "Putting ROV's ToWork Investigating Shipwrecks".Sea Technology. Vol. 31, No. 5. U.S.Navy. 1989. U.S. Navy AirDecompression TableHandbook andRecompression Chaeaber OjperatorsHandbook. BestPublishing Company, California.

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