MICHU-U-75-001 C3

in Marine Biologj

RESEARCH NEWSDIVISION OF RESEARCH DEVELOPMENT AND ADMINISTRATION UNIVERSITY OF MICHIGAN

FEBRUARY 1975 VOL. XV NO. 8

Cover: A walk under the sea, as illustrated in an 1874 American edition ofJules Verne's 20,000 Leagues under theSea.

fere is a path on the sea's azure floor,"keel has ever plowed that path before.

B. Shelley, "Epipsychidion"

WriterNi Blanchard Hiatt

DesignerSally Marty-Everhardus

Printed byUniversity of MichiganPrinting Services

4/RESEARCH NEWS

It has become a commonplace thatscience knows as much about the sur

face of the moon as it knows aboutwhat lies under the surface of the sea

or deep lakes. The exploration of bothouter space and "water space" requires complex life-support mechanisms and entails risk to those who

venture there. It is no surprise thatinvestigators are successfully approachingboth of these environmentsin capsules, which enclose a humanhabitat within inhuman surroundings. From such capsules persons inspecial garb—space suits or scubagear—can directly contact and

-manipulate the environment thatthey are studying.

Though underwater environmentsare much nearer to us than, those inspace, and though; they are mucheasierto explore than the moon, theyhave only in recent decades' received ,serious research attention. Onereason for learning about the seasis the fact that they harbor enormous reserves of resources, whichwill be available to humankind onlyafter extensive basic research.Another reason, of long-range importance, for studying the seas is ourawareness that the waters encloseecosystemsof vital importance to thewelfare and life-sustaining capacityof the biosphere. It may prove an jirrevocable disaster! to overestimate .the ocean's ability to sustain environmental degradation. The only way...to avert such a mistake is,to learnhow the marine ecosystem works and Xhow to avoid burdening it to the-point where it will no longer con-':tribute to a healthy biosphere. If -the oceans "die," that is, becomeradically altered in their biologicaland physical systems, the effects onhumans and on much earthly lifeare likely to be direct and severe.Now that we appreciate how important the oceans are to life as awhole—and know, too, how fragilesome ecosystems can be—we are preparing to protect our planetaryexistence by going to sea and takingits measure by direct contact.

Extensive research diving is relatively new to the University of Mich-

Sea Brant Depositee

Working on the coral reef.

igan, whose research program hasnever centered on marine studiesto the extent possible at univers-ties and institutions that are locatedon the ocean. When the MichiganSea Grant Program (Research Neus,March, 1970) made possible in thelate sixties the appointment of LeeH. Somers, who is now AssociateResearch Oceanographer in the Department of Atmospheric andOceanic Science and Assistant Professor of Physical Education, marineresearch received an important boost.:

-The campus now has facilities fortraining divers, including a hyperbaric chamber that simulates deep-water pressures, and a coreofnaturalscientists who- make use of theiropportunity to pursue research pro-

. grams that entail diving. These include the four investigators on theHydro-Lab saturation dive.

The University of Michigan is nowperhaps the leader among mid-western universities in the breadthand excellence of its marine researchactivities. Not only have 700 divasbeen trained over the last five yearsin the use of scuba and in surface-

supplied diving, but many of themhave also had a practical initiationinto the rigors of research divingthrough diving expeditions to theCaribbean. A course called\^Carib-

- bean Marine Environments" enablesstudents to practice what they have

; learned as they pursue individual research projectsat a site in the Carib-bean Sea. The course has been offeredin the winter semesters, and the trips

rtojthe. Caribbean have taken placeduring the spring breaks. In 1975

.' the^cpurse will be held at the Dis-covery Bay Marine Laboratory in Jamaica.. Students propose original research projects and qualify for thecourse by undergoing a conditioning program in the weeks prior tothe trip. All, of course, are certifieddivers.

The U-M programs in marinebiology and underwater technologyare providing excellent training fordivers, for whom there is now a goodjob market. At the same time the

' faculty members who guide these students are making progress in marineresearch. This Research News isdevoted to their work.

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Hydro-Lab LifeLiving conditions inside under

water research habitats have not yetapproached the level of comfortenvisioned by Jules Verne in hisdescription of Captain Nemo'sNautilus. A pipe organ has so farseemed superfluous, at least duringbrief stays under water, and thelibrary of seven thousand volumes,while it might not be useless to researchers during dives ofseveral days'duration, is a dispensible luxury.Yet Nemo would no doubt have approved of the safety and functionality,—if not the spaciousness ofHydro-Lab, an underwater researchhabitat in use off Grand BahamaIsland in the Caribbean Sea; Hemight even have'admired some of thetricks of modern technology'":that;.make undersea living more practical'than it was in his own day; "Andsurely, fascinated like his creator;;with the unknown, Nemo would have:-

-marveled at the findings of modern'investigators who, because.they canelive and work for extended perioo^in underwater habitats, are rapidly^remains for an extended period urider;:

;-cthe; elevated pressure of.deep-wateaf*;-^: submersion, makes it. possible forjft^vHr searefiejB Vto ronductj mvestigationa.;^|; t^ti;>wpuld; be impractical or^uiife:\ rwssible'from .a shore- or ship-ljased:i5,station:^Because it. takes hoursjto

^decompress a diver's)body afte£J$v•*^period, of dee'pwater work, it 'is!im|\c

fpossiblei?to find adequate timeT-foirany 'kinds of studies; unless one"

RESEARCH NEWS/3

acquiring a new understanding of therealms under the sea. What was fan

tasy one hundred years ago is todaya reality; what was once an adventurebuilt around a lust for vengeancethat drove a madman 20,000 leaguesis now a concert of purposeful investigation aimed at defining theecosystems of the seas and lakes andat making them useful for humangoals.

University of Michigan investigators are among those who studyunderwater environments. In earlySeptember, 1974, four U-M facultymembers spent a week inside anunderwater chamber, Hydro-Lab,never surfacing, and conducteddozens of scuba-assisted forays into the marine environment of the

.Bahama Islands. The four were,botanist .Gordon McBride, geological,,oceanographer Lee H.;.Somers, pale-":

•ontologist D. B. Macurda, and biPvlogical oceanographer;James Porter."This group had done; the sameJwbyears before and hopes to conduct

. Further saturation dives in the future..' -

laterally Jives- undej- the water^and^thereby avoids the frequent,. timer;consuming readjustment of pressure:that' human physiology requires;

HLiving under water is.accomplishedby a submerged chamber designedfor the purpose. Such a chamber isa home base to which divers canreturn at will, doff their gear, eat,and sleep, and from which they canswim away at whatever intervals arerequired to gather data, to makeobservations, or to perform experiments in a research project. Onlyonce at the end of days under waterdo they have to undergo decompression to prepare for return to sea-level pressures.

rsv:

6/RESEARCH NEWS

n/,0

the Coral Reef• Everyone knows'coral as the stone in .their variety of species than arethat.is laid^downjby coral animals. the: seas of middle and high lat-

''$j$£jffi"§fa plankton (both plant•s coral'polyps^arid'the biological com^. and'/animal types),. echinodenns,

;munitytof which;ihey are a part are; molluscs; and crustaceans all live in

;^,'.rhibit^ieir^ delicateiggreffiiye^nt^^^,.__. .__.^__ . _ ,. — ^ rr

i^'i^mou^ in Zoological equili^h^,.-like^th^liyfish;and^the^ bnmg&Within ^heir" .borders, reefr^^gu<»#?»V^^^^ip^sMmegwiy pi^uctivebiologtcally, con-!

'"art>i£Q°&ra^ degree of$m.$i<x>*d^^'^^Sfc^vpabl^lignt into^plaht and; later,

#^.:the^animal8*deposit a^^^^'t;aiu^^tissue. Reef^ecosystems dis->f calaum carbbnate on the su^w^vplay/j|'|dgh level of interdependence

£b^eath themselves. Acc^^ adVconditions and the kind of coral|^: vantagequs association. Perhaps most

BciSi^e^coral stones^^w^u^m^Bsti^of alLrreefe are also therii^pwyps Multiply from tiny, fle^gj'ddes^iving communities on earth,^^gre^^pebble^mto a.varie^bM^hawB^existed since1 the Paleozoic

^wnwlated^ surfaces!; and mtricat^^Era|^iver a half billion years. Be-Cllpfev:-¥J"W^: ' t 5;^fe«^W; -aU -these"characteristic8,'

-i x corapfieefs merit study. How havetheySurvived so well and so long?Whatvjinique adaptibility has keptthem .viable over eons of geologicalchange?!These are some of the largequestions that have interested U-Minvestigators in marine biology. Research expeditions, both.with andwithout Hydro-Lab, have helped inanswering specific ancillary questionsabout the history and the biologyofcoral reefs—questions that must beanswered if we are to understandthe longevity and' stability of theseunusual communities.

'A:- *-/ **reefs^ cover,- about one

i^^cen|fof'the oceans and .thrive'"'where;::;depths; are less than one-;

H: hundred meters and temperatures are•.-.-higher^than twenty degrees centi-.S grade.'Reefs provide the habitat for

a major part of the diverse marinelife of tropical seas. Whereas warm-water seas do not support as muchbiological activity as do cold andtemperate seas, the reefs are richer

vr. conunuous sneei upi livingJ^ahd^^^e^^^ajpparent kind of^iife^oniila", reek A%;night they es|-.

forms and^lheVithat surround>;

Coral polyps at night with tentacles extended in search of food.

desertr

Coral reefs have^unique biologicalsignificance. As biological commun-ities'.Xreefs are relatively small and

iut': they support

.00

Sea Weeds and Sea VegetablesThough we appreciate the bio

logical importance ofalgae, we understand the biology of algae far lesswell than we do that of land plants.On-site observation and monitoring ofliving algal communities presents difficult technical problems. Cultures ofmany microalgae can be maintained

"in research laboratories but manylarge marine forms cannot be studiedin such a manner. Facilities like un

derwater habitats and scuba are necessary before careful, long-term studies can be carried out. -c

RESEARCH NEWS/7

photosynthetic rate of three speciesof marine algae using recently developed oxygen electrode techniques.McBride's study aimed at learningwhether these species of marinealgae, which grow in depths offifty to one hundred feet, are totallyautotrophic or whether they are partially heterotrophic. Autotrophicalgae produce all of their necessaryfood by the photosynthetic processes,while heterotrophic algae derive partof their food from dissolved organicmaterial in the water around them.

The word alga is derived from aGreek term meaning "cold" and hascome to be the term for a verydiverse group of plants that evolvedin water environments. Some algae,like kelp, are large plants and mayeven grow in huge [undersea forests.Most are microscopic. Algae are biochemically a much more varied groupof organisms than land plants. Theycomprise ten divisions or, as we usedto say, phyla, one of which, the greenalgae, invaded the terrestrial environment and became the progenitor ofall the major divisions of land plants.(Some of these-land'plants like eelgrassand .turtle grass have reinvadedthe- lakes and oceans, but these arenot aigaet)^!; \"±.,^f̂ '^#£

The importance^ algae to life onearth can hardly be overstated. Algaecarry, on an estimated fifty percentof all the photosynthesis on earth.Hence they are the primary producersof a huge part of all the organicmaterial^ that constitutes the lowestrung onthefood chain. AlgaevirtuaUy/all of the animal life x>f

.The^seaTbiooms/and the oozy woods.which wear^Thejsaipless foliage of the ocean..... . ci~l-

^::.-^f^%,.^s- -. . ,.:•'• "••••"P. B. Shelley,'^'Ode to the West Wind" ;

oceans.^tlieyarefishes'that-are an imi

jnsiblefor^;source <

.'*;>".#&?:.3& •;

The study of marine algae is lessadvanced than some sciences. Muchof the research .in. ^narine.^botany

.m<^?'iast;decad^Bas,£eenMevofed.ttotdetermnin^ Mtes^of grqwih^pri-

humanfpo^ancC'tojjh£behefitofailjf^myaribus:communities. Algologjsts^;^ivvi^:.wh^the/on land or m^iarlwater,.they produce.

• Algae'carry ontheir photp^ynthesis^in an environment that rapidly filters7but thie| light ^that] photosynthesis'dependsiipon. To compensate'for thesometimes meager available'light;some groups of algae have pigmentsthat absorb wavelengths that are notabsorbed by chlorophyll. This lightenergy they then transmit to chlorophyll to increase photosynthetic efficiency. These pigments mask thegreen colorof chlorophyll and provideidentifying characters for some majordivisions, - such as the red algaeand the brown algae. Some algaehave the capacity to absorb chemicalenergy sources by which they supplement the food production of photosynthesis. A»few algae have lost theirphotosynthetic capacities altogetherand simply absorb food from theirsurroundings like fungi.

_.. or;in|£^raamounts bfsfelearningto^distmguislr'the!life stages

\ot algaLspecies: lt^is common to read{in^thle;^ientificjpterat^^botanist's.< discovayxtMt5species x|is really a stage ^m'.the ltfe/history'of speciesy.:NotIchowingsuch factsmakesit difficult^' comprehend the

".biological^, communities; vof"^whicfr ;. algae are a basic part. >J.tlis11ike' studying caterpillars without knowing that"they become butterflies ormoths. Yet one obviously cannotstudy a marine habitat with the sameease with which he can watch theprogress of a cabbage worm. .

The 1974 Hydro-Lab saturationdive helped obviate some of thedifficulties of marine botany by permitting Gordon McBride,-AssistantProfessor of Botany, to remain present for an entire week at the site

of a living biological community' under the sea. The week-long divegave opportunity to measure the

t%*r •>'--• m:

if. .'.:-[.;

The matter of^heterotrophy-^ndautotrophy in marine; environmentsis enriched by some interesting complexities. The marine algae that are-.found? in- some .areas,;:such as-thevery deep. •?>tropical ^•Waters.'. andunder the polar ice packs/may have :avi capacity not only$&lvphotosyn-thesize- but also to'derive some oftheir nutrition heterotrophically^Itisotherwise' difficult^to^explain their.presence"-in regions-where availablelight is so low. The saturation divein September 1974-has proved theapplicability: of in- situustudies i^of

;. photosynthetic and respiration rates•'• in intermediate . depths. WThe next

step will be to carry this sort ofresearch to deep water or .under theArctic ice, where McBride hypothesizes that heterotrophy in algaewould be most evident.

From Hydro-Lab McBride studiedthree genera of algae, called Penecil-lus, Halimeda, and Riphocephalus.These three types of algae areespecially important because, inaddition to their role as primaryproducers in the food chain, they.create the carbonate sand that formsmuch of the substrate in shallow

tropical waters. By a process, not wellunderstood these algae are able to pre-

8 / RESEARCH NEWS

cipitate on their surface the calciumand magnesium carbonate from surrounding sea water. As the plants dieand the organic matter disappears,the carbonates are left behind as sand,which accumulates in huge quantitiesover a period of time and eventuallysifts into the depths. Eons later suchlayers of carbonate may reappear onland as strata of limestone.

In the study, several plants wereenclosed in clear plastic chambersthat had a volume of about oneliter. Here it was possible to isolatethem from their community andmeasure their photosynthesis and respiration. The chambers are eachadapted so that McBride could insertinto them an oxygen electrode probeconnected to a device that measuresaccurately how much oxygen is present in the water in the chamber. Bymeasuringthe change in oxygen concentration over a twenty-four-hourperiod, McBride was able to determineif the algae were ableto produceenough food (namely, sugar, production of which is proportional to production of the oxygen byproduct) toaccount for the amount of food (sugar)which -. is respired during, the sameperiod of time. A net accumulation ofoxygen oyer-twehty-four hours wouldindicate that the photosynthesis-respiration, or P/R, ratio was one orgreater than one, andthat thesealgaewereLautotrophic. • Some containerswithout algae were left as a control;they would detect any change in oxygen concentration related to microorganisms in the sea water.•McBride.took1 oxygen readings at

two-hour intervals, at the same timegauging available light on a lightmeter. After each alga had yieldedits metabolic .information in itsnatural habitat, McBride harvestedit and saved it for later chemicalanalysis in Ann Arbor. Although theanalysis phase of the project has notyet been completed, the indicationsare that at forty-five feet of depthplants have a P/R ratio higher thanone. Hence, heterotrophy does notseem necessary to account for thepresence of algae at this depth.

McBride plans to continue thesestudies both in the intermediate

Halimeda tuna, an alga thatprecipitates carbonate from the seawater. Deposited on the alga's sur

Penecillus dumetosus, form expansa, anew species that Gordon McBride isclassifying in the botanical literature;

depths and in deep waters, but atpresent no underwater habitats areavailable that .would facilitate research at 100- to 200-foot depths orunder the Arctic ice pack wheresomeof the most interesting questionsabout algal energy budgets could beanswered.

McBride is also continuously involved in observing the species ofalgae in marine locations and analyzing their distribution. During the

face, the .carbonate becomes sand whenthe alga dies. >i .

it was formerly thought to be the sameas another species.

1972 Hydro-Lab saturation dive hesurveyed the algal populations in theinfra-littoral region, the sea bottomat depths below the lowest tidesdown to about ninety feet. Duringthis study he collected numerousPenecillus specimens ofanapparently new species that is generally restricted to deepwater environments.This material is beingcompared withthe only other similar specimenswhich were collected during a dredg-

1

Plexiglas containers that isolate algaeor coral polyps from some aspects of.their habitat. The investigator is electronically gauging the amount of ox

Penecillus capitqtus being photographed by a research diver.

ygen dissolved in the water in thechamber to learn about the metabolism of the creature within.

RESEARCH NEWS / 9

ing operation prior to 1913 and areon loan from an herbarium in Denmark.

Another continuing research effortis the gathering of life-historydetails about marine algae. Just asone cannot understand an oak treewithout observing in turn its buds,leaves, flowers, acorns, and dormancy, so marine botanists remainrelatively uncertain about algae untilthey have seen them in all seasons.One of McBride's students, Steven D.Bach, is currently diving off theFlorida coast, conducting long-termresearch on the life span, growth rate,and productivity of Halimeda,Penecillus, Udotea, and Riphoceph-alus. Bach's study has now beenunder way for over a year, and he hastagged and continuously observedover 800 individual marine plants ofthe four genera named. He hasrecorded their life histories: how longeach one lived, how fast it reachedmaturity, the conditions that fosteredits growth, and the predators thatinhibited its growth: In principle, this

^ research isnodifferent from studying1Jl&the plants in one's backyard garden-flf(Will my broccoli reach reproductive4£'-maturity sooner ifT plant^it«in dayitfj-here or 'In. gravel over.-there?); but££the" practical difficulties' are"much^greater. Bach must put on'scubafiland diveevery few daysto keeptrack^•'of changes. His- results have yielded>J£ a number' of; interesting new facts,; and he has shown that the generally~V held notion about the generation time

.fe-of these algae is incorrect. PenecUIusjv--.plants, for:example, live less. than

"*\ three months, before they decay andv^yield up their nutrients to the ecosys-tl': tern; while'Ha/imeda plants last six

months or longer:• The results of Bach's dissertation

will provide important informationfor agencies, concerned with pollutionproblems and management of subtropical shallow marine waters, whichare important breeding grounds formany commercially valuable fish andwildlife.

10/RESEARCH NEWS

o° i

Zooplankton of the Coral Reef

The next rung above phytoplank-ton on the coral reef food chain iszooplankton. the subject of investigation of Karen G. Porter, AssistantProfessor of Zoology. Zooplankton,which are the small animals (upto three millimeters) that live anddrift in the water, include a largevariety of species of crustaceans,annelids, polychetes, and larvalforms of various creatures. Porter's research has taken her to theCaribbean Sea and to the Great Barrier Reef of Australia. At coral reefsand atolls she has studied zooplankton using some of the same techniques that freshwater, biologists(limnologists) employ to analyzefreshwater zooplankton.,, ,v:£-:^

In fact, Porter herself is primarilya student of freshwater zooplankton,but she devotes about one-fourth ofher research effort.to marine plankton. She. makes an important contribution^ to the study, of -marineplankton^because ofJier>famiharitywith research techniques.that.havebeen devised to .study plankton inlakes and'streams.^Biological.ocean-ographerav-also study, marine ..zoo-planktqn,:but to a great extent theirstudies^are hmited- to. the -plankton thatthey have netted from boatson the open sea. Such studies are notwithout.value,but it is also possible

'to use the precise techniques thathave beendeveloped in the relativelytame freshwater milieu to;study theplankton of certain marine, environ- :ments, particularly the coral reef andits lagoon andbackwaters. As it happens, many freshwater and marinespecies of zooplankton are not strikinglydifferent in their behavior, andthe study of either group complements the study of the other.

Porter is also intrigued, with theconcept of lakes as "wet islands." Shehas carried this concept of islandbiogeography to fresh waters on theWindward and Leeward Islands,which lie in a chain between Floridaand Venezuela. Such islands oftenhave pools or small lakes, especiallyif they have a mountain high enough

to create a perpetual rain cloud thatkeeps pools filled. One might supposethat such pools would be filled withplankton that, through isolation, haddiverged from the mainland types.But Porter has found that this is notso. Lying under major bird flyways,island pools harbor many of thespecies that can be carried there frommainland waters on birds' feet andfeathers. Some day Porter hopes tostudy the zooplankton of pools andlakesofthe Galapagos Islands, which,as Darwin first noted, are a living-laboratory for the study of evolution.Theseislands are not onany flyway bywhich birds couldbe constantly reintroducing mainland species of plankton.' Thus evolutionary divergence.may' have taken place among zooplankton there as it has among thebirds, tortoises, and lizards that Darwin studied. In what wayswould theirisolated environment- have causedsuch divergence to go? The kinds ofdifferences that Galapagos planktonmight exhibit could shed light onecorlogical i-relationships • in;, vmainland

f-'.V^?^'

smaller than most zooplankton. Tofind and count such plankton theydonned scuba and swam over a prescribed course dragging a six-footfine-meshed net to capture a sampleof plankton. By swimming a certaincourse .at several depths and at two-hour intervals, the Porters were ableto gauge the whereabouts of planktonat particular times of day and night.Information was gathered duringhorizontal "pushes" at various constant depths on courses along theshoulder of a reef,, as.illustrated inthe accompanying photograph.At thesame time vertical V'hauls" weretaken, drawing in all the planktonin a^cplumn of water from a depthof thirteen-meters upVto the surface.

The results of these data-gatheringswims are summarized in the graphon page 12. The quantity of planktondetected by pushes orhauls wasquitelow during the day.'Atnight it"isquite a different story, for, then theplankton come out of hiding in the

.»4jpck crt^ces at theireef surface and.to,; ^ate^^B^gce. Atdawn

rrof movement

Full'many a gem of purest ray serene,The.dark unfathom'd eaves'ofoc^ b^Thomas'Gray, ;'-V'"''v'%£?;£*"Elegyin a Country Churchyard" -v. '?,*;&?^i!i'-''jf

-:-w

; While she was in tropical waters,Karen /Porter' and her husbandJames,'who is an assistant professorof biological"oceanography in theSchool of Natural Resources- (seebelow), devoted most of their timeto the plankton of coral reefs.Here the goal was to sample andassess the density of demersal plankton, animals that live by day in rockycrevices and by night migrate sur-faceward to reproduce and feed, oftenon tiny algae, or phytoplankton,one-celled plants that are even

-"-• , .- " V

before they resettle to the reef surface. .When the plankton move atdawn and dusk, they render themselves available as food, especiallyfor the coral polyps.. In this waythey play their role in the food chainand energybudgetofthe coral reef,aswill be discussed in the next sectionon energy-flow in the reef. This studyis the first to providequantitative andaccurate information about many ofthe species of reef zooplankton andtheir habits.

In future work on the Great Barrier

Reef, at atolls such as that surrounding One-Tree Island (pictured; it hasone tree on it), Porter hopes to useother freshwater techniques andmodels to help her learn more detailsabout the life habits and ecologicalroles of plankton.- An atoll is not unlike a lake, according to Porter, insofar as during low tide it is a shallow,calm, saltwater pool separated fromthe surrounding water. Hence, like alake, an atoll has a flushing rate,which is the period of time it takesfor its water to be completelychanged. And it possesses its ownrelatively isolated and internally adjusted biological community. Manyunanswered questions about suchatolls can be approached with thesame freshwater techniques that havealready - served in >the - study ofplankton of the open reef. Withinthe atoll as^a whole are micro-atolls, often as small as backyardswimming pools, each ofwhich can betreated as a laboratory and manipulated to reveal the characteristics of

various biological parameters.The flushing rates of micro-atolls

can be determined by placing achemical' "dye," in the.water duringlow tide,;then-checking the next dayand,the next to see how much ofthechemical remains behind, not washedaway. by:^mtervenihg. tides. Theflushing rate determines how fastanimal wastes are eliminated fromthe pool and how much open waterplajikton .is: mtroduced. Density of

- plankton can be measured convenient-'ly and related to the mass of bottom(coral) tissue in a given,micro-atoll to .shed light on.its role in the biologicalproductivity, of the atoll..- J

It is also possible to learn about thekinds of planktonic algae that bearthe brunt of grazing by zooplankton.By dropping a fine net over the bottom of a -small lagoon, the algaein the water column can be separatedfrom their zooplanktonic predators,which are too large to rise through themesh. By comparing the numbers ofalgae in micro-atolls free of predationwith those in normal micro-atolls, onecan infer what species are the onesmost grazed upon. Such a separationof algae and zooplankton would also,

By pushing a net along a prescribed underwater course at intervals during theday and night an investigator can cap

One-Tree Island, the dark spot at theupper right, within the atoll that surrounds it. Such atolls are excellent sitesfor performing a variety of studies of

RESEARCH NEWS/11

ture and measure the quantity of plankton at a given depth.

life on the coral reef. This atoll is partof the Great Barrier Reef off northeastern Australia.

12/RESEARCH NEWS

by preventing the demersal zooplankton from rising to the surface,indicate whether feeding or reproduction are the main activities for whichthe zooplankton rise nocturnally.

Details of the sort that Porter hassought and plans to continue seekingare important if biological systems—ecosystems—are to be understood.The section below shows how information oii plankton can relate to thereef community as a whole:

10• Vertical Haul

O Push at Om

A Push at 13m

Moon Set

This chart records'where plankton wasfound at different, times of day. Because they hide at the reef surface during the .day, methods of detection dis-

W&^-Flow in the Tropical Reef'-No onehas yet gathered enough in-

formation^about life on coral reefs toundOTtand fully how they survive. Infa(^3gust^ lt.Was once shown thatthetbumbiebeVcannot fly, the coralreefJaas.appeared to some notto have,sufficien^jesources for its own suste-.nah&ft.Yetfree'fsthrive, and they havedone so-;for-ah>astonishingly .long'tune.^T6|^^erstarid their longevityand"appareni^stabili^ means firsttt^rsj|^|(Sg^hby^^divene:organismstoft the coral'reef acquireandj.exchange^energy inva harmon-:iouasyste^TW, in general, is theresearch -aim ."of James W. Porter,husband of Karen Porter,whosework .was;described above, -y'"".-''- .'.

The research entails first-hand observation of and experimental manipulation of community relationshipsamong reef plants and animals—thestudy of who eats whom. Reefs haveseemed an enigma formany years because they survive in nutrient-poorwaters and because they werethought to harbor little plant life,whichwouldproduce food and energyand form tho basis of a food chain.Porter's recent work in the Carib-

bean, aboard Hydro^Lab tends toshow;that there is a.good deal moreprimaryvproduction by plante thanhas been recognized.^These plantshaveubeen missed because they areone-ceiled algae that-live inside the

, bodies jpf coral polypV. These algae, ip>.concert* with the tight, recycling Ipf

biological, materials that occurs dnreefs,make possible the sustenance ofa biological community that appearsto have only an inadequate input ofenergy.and food resources. • •>;,i§. Working fronT Hydro-Lab, Porter.used"techniques similar to those'-bfMcBride to study caloric requirements ;of coral animals and thesources of food that meet those requirements. He got a measure of thecalorie .needs of one coral species,Montostrea cavernosa, the star coral,by sealing a number of those individuals inside separate plexiglaschambers. Porter took oxygenmeasurements in the chambers everytwo hours to determine how much oxygen each coral had consumed; aftereach reading he flushed the chambers with oxygenated sea water tokeep the coral healthy. By gauging

-rr~

l\

Mozn Rise

cover few plankton. At night theymigrate, making themselves availableas food to coral priyps andas data to investigators.

.v-'-

oxygen consumption and, if any, oxygen production over; a1 twenty-four-hour period for each individual;' hewas able to cakulate the calories thateach animal consnmeA,^'^ ;^r-\-''

But knowing the'caloric•'requirement of an individual of a given sizeis only half the problem. How arethese calories supplied? Porter investigated; this"by extracting at intervals the contents'ofthe gut fromindividuals ofthe same species livingon the reef. He studied the ingestedmaterial';under a microscope to 'seewhat kinds ofplankton it consisted ofand measured its caloric value. Theguts were fullest of plankton in themorning and in die evening. Further,virtually all the plankton ingested bythe coral animate were species thatlived on the reef; notably those demersal plankton that migrated atdawn and dusk, rather than speciesthat happened to drift in from thesurrounding sea water. This indicated how complete is the recycling ofmaterials that takes place in the reefecosystem.

He learned something else as well,that only twenty to thirty percent of

Sz>_i

o>

iu

U<u.

IT

The larger the diameter—and- hencemouth size—of a coral polyp (right sideof chart),; the better it can make use of

• plankton as a food source. Polyps thatare small (left side) can make less useof such, food sources, because their

>' ',•'••"<"•'-,'-%.'.'*•• - ' •r-'. "-'

-.. -M> >*:^$'-:'i"'• ••"•'-•• -=--'-•' -'"•*•'•-.* —V '-."'.:' V*-y-'.'• '•> .: ' '".'•' . •"

- . . -:' ; -- t - .•, - -*-*., . .... <• --\:-. r./ . V.v - - '—r-i-'-: '" ' v

the caloric-requirements of .an indirvidual M cauernosa polyp is met bythe zooplankton it ingests.1-All therest,; >palgae^aimye: s;theanun'S^pf^"

algae the:remain> auve;<

d what milk'cbo

slaughtered|beef?reef^^^^4^^^*& i*""'&growing:algaej depend on smallf

Thtestudy^whic[hconcentrates on*; plankton to make-up only;"a few cal-one speciesJokcoral,rleao^to ab^ ories that they cannot get from their;question whichjPorteris'also tryingtoiv internal algae.: The' accompanying

not digested but-' ,'V'y^>''-.-':. * -'

answer. Whatfare the food aridenergy-budgets ofcoral species otherthan M.cavernosa - (there are sixty on anygiven Caribbean reef) and of the reefas a whole? To answer this he has surveyed the, relative distribution of different types of coral animals andcategorized them. The sixty types fallalong a continuum from those withsmall mouths and high surface-to-volume ratios to those with largemouths and small surface-to-volume

ratios. The species with large mouths

mouths are too small, but theirrelatively large surface areas admitplenty of light into their bodies, wherecertain algae can live and produce byproducts that nourish a coral polypfrom within. - «>,_:,....; •J-;~lv.

(up to 61 mm across) can take considerable advantage of the foodenergy available from the full range of

come^from -the ,;, plankton h^nginthe reefs Their rela-.bi6ticaij£|rai^^^dyjshowsthatl^v light^absbrb'ing

^cuauv. meagerdtyfacTcord witri-

the, diminished dependence on syrip;*•-. •;.- *^-Diotic•%jj&&*l£0^-yfife$9'r

alsb^cubobj^ the algae forjtheif calorie!and ;metebai^ needs,\then they^would ha^tohave,;

.f

r asdo tiie smaU-mouthed'^fals, largeirter'8 .*simile^theii\ surface-to-voium^areto'thecor^ «-^^L«"^*£-&«2i%^

dat&ton?«re"the!ttle of the Wai:

:among' the dgae^witbin.:Tiie.8mall-icorals.^with*their,mow

chart depicts--the continuum between these two extreme modes of

coral nourishment. Such a con

tinuum demonstrates how species ofcorals, like many animals, partitionthe available resources and mini

mize direct competition for individual "commodities," whether these besunlight or plankton protein. Furtherunderstanding of the partitioning ofresources leads to a complete analysisof . energy-flow and communityequilibrium.

RESEARCH NEWS/13

Space is another valuable commodity to corals. All animals requirea certain amount of space to live in,and they must generally compete forit as they do for their food. Porter hashad a chance to study coral communities that contrast in their stylesofspace partitioning. At some sites oneither side of the Isthmus of Panama, corals live densely packed. Onthe Caribbean side, this density entails a large number of species; on thePacific side, high density is associated with the presence of relativelyfew species. At such sites in thePacific one coral is dominant in most

competitive interactions and thus,the denser the coral growth, the morethe. growth is likely to consist of thisone species. On the Caribbean side,however, competitive exclusion byone species does not occur:

It happens that the dominantPacific coral is not able to wipe out allother corals even though it has a competitive edge. This raises impracticalsidelight on Porter's work. A type ofstarfish eats the dominant coralspecies and is thus itself. abundantwhere, the coral is abundant;. Somehave worried that "this predator, theCrown of Thorns starfish,. &-a threat

' to coral reefs in'the Pacific because it'' appears so voracious and abundant atsome, sites. Porter believes that..thestarfish can actually" control'theotherwise dominant coral in a self-

. regulating predator-prey ''relation.^ship that has some of its"origins in acertain style of space „partitioningamong corals,' - '.'" ' - •

'Further studies of coral may takePorter back to Australia to One-Tree

Island and the surrounding atoll andreef-in the Great Barrier Reef. Here

he wants to use the micro-atolls as

individual cells in which to manipulate and measure the variables thataffect coral life. For example, hemight alter the energy-flow of onemicro-atoll community by removingits Crown of Thorns starfish. One-Tree Atoll is near the world's only underwater park, established by theAustralian government, which has inthe past supported some of Porter'sresearch.

14/RESEARCH NEWS

rP c*

A New Science: Paleoecology

Many forms of undersea life are exotic and rarely come to the attentionof most of us. If the layman knowsanything at all about crinoids, for example, he is more likely to rememberthem in a geological context—as fossils—rather than as creatures still ek

ing out an existence in the depths ofthe ocean. Yet crinoids are still with

us after 500 million years of persistent and successful evolution.

Crinoids are echinoderms, relatives ofthe starfishes. Like starfishes theyoften have long arms (usually morethan five) that curl gracefully in thegentle currents where they live. Littleis. known about-them because theirhabitats are remote' and their uses toman negligible. Yet-they are peculiarly significant in their evolutionary tenacity. Understanding thehabits and habitats of modern crinoids can lead to inferences'about thebiological communities and environments associated with, ancient crinoids. Their study can-thus help uspiece together systematic informa-

„tion about conditions of. the' Paleozoic Era'thatmay be otherwise !un-possible to reconstruct.* / .' '4?.' D. B, Macurda, Jr„ Associate Pro-

: fessor ofGeology and Mineralogy andAssociate Curator of Invertebrates atthe. Museum of Paleontology,•/ 'hasmade use.of submersible vessels andunderwater habitats, like Hydro-Labto acquaint himself directly withliving crinoids. Such studies have enabled Macurda to go.beypndthe laboratory studies of crinoids that formthe basis ofmuch that is known aboutthe creatures. Such studies, in whichcrinoids are observed in aquaria, haveled to certain misconceptions aboutcrinoid habits and have taught littleabout their long past or their presentdistribution. The 1974 Hydro-Labsaturation dive is the most recent ofMacurda's several data-gathering efforts, and he found it immenselyhelpful. From Hydro-Lab at forty-five feet he was able to dive twiceeach day into the 130-150 foot range.Four such deep dives of forty-five

minutes, which took two days to accomplish from Hydro-Lab, wouldhave required most of a week hadMacurda started out each day fromthe surface. His relative freedom of

movement enabled Macurda to spotcrinoids and commensal shrimp thathad not been thought to live in watersas far north as the Hydro-Lab site inthe Bahamas.

To date Macurda has surveyedcrinoids throughout the CaribbeanSea by dives from the Hydro-Lab,the submersible Nekton Gamma(pictured), the research vesselColumbus-Iselin, owned by the University ofMiami, and small boats. Onthese trips he has taken over 200 rollsof color film. Photography is an especially important tool to undersea research, useful not only for showingothers what one saw but also for pro-

A submersible vessel used in underwater research, the Nekton Gamma is

viding details that cannot bepondered or even noticed during thehurried forays that diving timetablespermit.

When Macurda dives he takes with

him a unique tool. In addition tocamera, hammer, specimen box, andplastic slate for note-taking, hecarries a magnifying glass of specialdesign. Ordinary magnifying glasses,designed to refract light that is passing through air or empty space, do notwork in water, which has its own refractive characteristics. Macurdaread about a design for a workableunderwater magnifier- and had onecreated. Made ofbrass, it looks like alarge and heavy gavel. It uses threelenses with spaces between the lensesthat are filled with water, whichenters through small holes in thebrass frame that holds the lenses.

based at the Discovery Bay MarineLaboratory in Jamaica.

This graceful creature is a stalkedcrin-aid, Cenocrinus asterius, living atalmost

A close-ap of the arm of a non-stalkedcrinoid, Nemaster discoidea.

1,000 feet of depth. It was photographed from the Nekton Gamma!?. '.~

RESEARCH NEWS /15

This combination overcomes the

limits of other underwater opticalmethods and permits magnificationof four times.

One of Macurda's discoveries pertains to the method of feeding thatdeepwater stemmed crinoids use. Experience with crinoids in the laboratory indicated that they hold theirarms and pinnules ("little feathers"in Latin) upward like a broken umbrella and feed passively by awaitingthe fall of tiny organic particles fromthe water above them. But there is akey difference between an aquariumand the natural habitat of most crin

oids, which Macurda has learned areadapted' to living in moderate currents. Thus, as the graceful crinoid inthe accompanying picture indicates,the arms of most species of stemmedcrinoids are oriented by the current,which brings food particles from theside rather than from directly above.Many direct observations by Macurda and by his colleague David Meyer

, of the Smithsonian Tropical Research Institute bear out, this dis-

• covery.• Such information about the life

' habits of crinoids becomes especially•' interesting when viewed injthe .con-• text,: of the microstructures - of the'creatures' skeletons. Macurda is currently spending an afternoon each

•week with the scanning: electron; microscope, to make pictures of the. details of the^structure of crinoid

A'animals.' He correlates their micro-.; structure with what he knows about.:;their, habits and environments^ An-' unknown.;'>or . unstudied^'deepwater

crinoid can now, through its' micro-structure, be compared to known

'• crinoids and made to yield .clues: about its life history and the condi

tions in which it lived—including currents, water temperature, and foodsources.

But even more important, thedetails about. modern crinoids canshed light on ancient fossilized crinoids, whose microstructures are preserved in stone. The differences andsimilarities between crinoids of 275million years ago and those of todaycan help to point out the kinds of environments that prevailed in the

16/RESEARCH NEWS

Paleozoic Era. The study of ancientenvironments is called paleoecologyor paleobiology, and it is a researchfield that is coming into prominencethrough the development of methodslike Macurda's. By visiting fossil sitesrich in crinoids, two of which, forexample, are in New Mexico andMissouri, Macurda plans to gatherdetails that he can correlate with hisknowledge of modern crinoids. Thetwo aforementioned sites are of different ages, and the nature of differences between crinoids at thosesites will indicate the direction ofevolution and the progress of environmental changes. Solid data oncrinoid life histories and rnicrostruc-ture now makes such research possible.

Another problem that Macurdaplans to takeiip is a theoretical study

involving a majorecological assumption, namely that no two species in agiven environment use exactly thesame set of that environment'sresources. The conventional wisdomholds, in other words, that every environmental nichecanbeoccupied byonly one species. He has a researchgrant that will enable him next yearto travel to Indonesia, where eighty toninety types of crinoids live. (TheCaribbean, like the North Atlanticgenerally, is relatively species-poor inmany groups, owing probably to therelativelyrecentchilling effectsof theIce Age and the environmental disruptions it caused.) Macurda believes,he may find among those many,crinoid species some pairs that usetheirenvironments in identical ways.They willthus eat"the same food, enjoy the same currents and tempera

Reef, Worms: Seen But Not Touched61o

• The 'dramatically colored monarchbutterfly^does; not, in evolutionaryterms, look pretty merely to beautifynature: Itei> vivid*color draws attention and ensures that any creatureseeingthe butterfly recognizes it for amonarch. The -monarch butterfly'smain defense against predation is itsbad. taste, which is known to predators; By. being easily identified, themonarch' can avoid being attacked.The coral reefis fullof many colorfuland' eye-catching, creatures ?thatalmost seem to be competing witheach other for visual attention. Thebeauties of the reef may.not all owetheirexistence to predator-prey relationships as does the beauty of themonarch butterfly, but in"at least onecase such relationships could be theexplanation.

A serpulid worm of the coral reef,Spirobranchus giganteus, was foundby Lee H. Somers to be apparentlydefenseless against predation by reefanimals but never to suffer attacksunder natural circumstances. Thoughnot a biologist, Somers took advantage of his time as diving officer

aboard Hydro-tab in 1974 id observethe serpulid worm in its native habi-:tat. Little is'knownabout the worm's'life on the reef and its relations withpotential predators.'

Serpulid worms are a family that:belongs to the phylum Annelida,which includes the familiar earthworm. The species. under' studymeasures two to three inches long.Serpulids are classed as tubiculousworms; they live in tubes formed frommucous secretions and sand or otheravailable materials. Most of a ser-pulid's body remains sheltered insideits tube, and only its feeding partswaft freely in the tropical waters. Thebodymaynever come outof the tube,andthe tentacles, asobserved duringtins project, are almost as seldom retracted into the tube. The feedingparts of the creatures,, which areshown in the accompanying photograph, are graceful tentacles thatpick up tiny organisms from thewater and transfer them to the innermouth parts. These filamentous ten- *tacles have caused the creatures to bedubbed "feather-duster worms."

tures, grow in the same sort of location and substrate, and so on. In theCaribbean Macurda has foundspecies that come close to perfectoverlap in their use of the environment, and he believes that among thelarge number of South Pacific specieshe may find some instances of complete overlap. Many modern ecolo-gists are interested in the possibilityof complete overlap. If it occurs, itmay mean that the better competitorof two overlapping species need notalways cause the extinction ofthe lessable competitor. In any case, Macurda may be able to demonstrate in theSouth Pacific that crinoids may overlap in their, use of environmentalresources and hence, by inference,that the same may have been'true oflarge numbers of Paleozoic crinoids.

,-. v •-,.•;?. •-ft '••vTvjf.'-"

-.•*.%•,• *»

.-8

• - "#-"S^- •-••"' •-• •''• •'-•'•*••'*£Av-y- ••{•Ji-j*-.t . >..- • ,-"•-•- •:>.*«

•'•" '•?•-•••'' .x;'"-M---^'-> ••'• •>•-•••''' -'^.^t--• •<.^:-^*x^*:-{>* ••£*•>. >•.....;.-;•

Somers: observed selectedspecifmens' of S. giganieus forta^total oftwenty-five hbursj^uring'theaaJtura?

;' tioh <live. He'fiowredin theiwater^atsufficient distano^firom the worms toavoid disrupting-jtheir habitat.' Dur^ing the periods of observation)Somers saw no fish, crab, or otherpredator atteck-ythe" tentacles. Nopredator displayedi much interest'ofany sort. The worms themselves; remained -obliviousi jiof/anyicompany-Even .when a crab or fish touched; aworm; the worm, did not retract itstentacles. ' •" "T^Vr-- .:,i • ' '•; ;jj.

Then Somers ^experimented bypullingsomeof the;worms out of theirtubes. Stripped of. their cover, theworms elicited quite a different reaction from the disinterest hitherto exhibited by predators. Fishes, particularly, wrasse and damselfish, immediately ate them up. But they didnot eat the tentacles, eschewing themfor the body parts that are not customarily exposed. The lovelyplumage continued to repulse predators.

Why this is so Somers does not yet

-•V ;^ftv

%mm

•-•• .-;-•.-.•. :i'.>-':i----'-,t'-.v. ^- 'know, but a likely explanation is thatthe serpulidtentacles,.which must re-i.mamtpassively^exposed^to predatorsifthelserfutfd ^evolved;^l)i^d^sting chemical.^Aridpredaforef|l^ye*inj turn--evolyeSlto.iavoid this bad taste. The dramatic

appearance of the! tentacles ^furtherserves to ensure that the worm is not

mistaken for;'another creature .thatpredators^ find tasty. During ^thespring.of 1975 in; Jamaica Somersplaju.'Ho'yiriyestigate;'the•repellentnaturejofthV^ntacles:'';' '-'•••'•• .

Thus the feather-fduster worm survives and adds its beauty to the coralreef. Not all of the reefs beauty ofcourse is likely to have ah explanation like that suggested here. Indeed,the reef as a whole may be, tohumans, a matter of beauty in the eyeofthe beholder. Underwater life is exotic-and, its forms can be verydifferent from those of land creatures, which must be sturdy and upright against gravity. No doubt thebeauty of the reef is, to some, amplereason for studying it, but the scientific revelations that reefs may yieldare an even better reason.

Lovelier than the earthworm to whichit is related, the Spirobranchus giganteusprojects its tentacles while it hides itsbody within a tube in the coral head.

RESEARCH NEWS /17

The exposed feeding parts are apparently tistasteffol to predators, whichrefuse to mack or eat them.

IS/ RESEARCH N^YS

Sport^Dwing^afety*?•?.

'J.. The publfcoftenthinWroastakenly •that scuba'.diving is a dangerous ac-'tivity. Persons who hold their breathwhile they watch James Bond swimunderwater.in the movies are quite,likely to exaggerate the. hazards'ofdiving. In fact, scuba diving seems tobe no more dangerous than a numberof other sports,"like swimming, skiing, mountain climbing, and boating.It may even be true of scuba diving,as it is of'deer hunting, that one'schances of having an automobile accident en route are greater than one'schances of having an accident in theactivity itself. Diving need not be unsafe at all. In the experience of Lee H.Somers and the diving program at the

jU^vereity.ofMichigan, 3,000 person-hours ofdiving over a five-year periodhave passed without incident. Among

.the 700 divers trained during that-period, Somers has heard of no sub

sequent accidents..' ' Yet sometimes divers die, and accidents are always a possibility.There have been about 125 reportedscuba deaths in this country each-year since 1970. This does not meanthat the sport is not growing safer, forin the same period the number ofscuba divers has trebled. In Somers'view virtually all scuba deaths can beavoided if individual divers follow the

safety guidelines they are taught.Fostering diving safety is a major

sWew:-!'--;--^.;

•^•im-yy

concern and activity of Somers. Having -succeeded in. establishing 'aresearch diving program at the University of Michigan and at sitesaround the Great Lakes, the'SeaGrant Program and. Somers . haveturned some of their attention to theneeds and problems of recreationaldivers, whose numbers are increasingrapidly. Shipwrecked vessels, manyof which are accessible within the130-foot depth limit to which mostsport divers are limited, give theGreat Lakes considerable appeal toscuba enthusiasts.

Somers' goal is to learn the humancauses of diving accidents. Becausehe has never heard of a scuba death

The Deep DivingSyndrome

In ahai ' t to meetsome of

:,-^',a.'i,*.^}'

:- a^-'-.-i .,';': ' f---- '•'*»<?*• -:>i*;J:attributable to.the failure of properly,maintained, equipment, he -is con-'cemed primarily about the judgmentof individual divers, their physicalconditioning, their understanding ofthe physiology of diving, their abilityto use and maintain their equipment, and their knowledge of and respect for the underwater environment. These matters are best approached, in Somers' view," throughdiver education. Diving programsaim at instilling in divers correct attitudes about their activity and a sense

of caution appropriate to the potential dangers.

What are some of the errors thatdivers can make, and what are theconsequences of diving accidents? Itis relatively easy in the excitement ofa dive to transgress the safety limitsand to find oneself faced with a disabling injury or even death. Thesummer of 1974 saw several diverdeaths in Michigan, and Somers estimates that there may be in the statea dozen minor and untreated cases ofthe bends each summer weekend.Even a mild case of the bends can, ifnot treated properly, result in a longdelayed arthritis-like condition or,

- still worse, the death of bone tissue.Divers can get into trouble owing to

; poor judgment and to lack of respect.'; for the underwater̂ environment and-. its elevated pressures! Divers who are;• lax about their safety guidelines can

be said only to have been "lucky sofar.'' By lending to their sport ah inappropriate, air of bravado, suchdiverstcan have a• bad.influence on'

.others:,Diver8:mu8t never forget the% limits of:their ,qwn physical fitness,

••>. endurance, aindy skills.. Exhaustion:h may:.creep up on,'aAdiver and cause••*•_him.to.ma^^jfaulty decisions in.an

•s&:;?&^Wi^ diver •of the sport diving public. tkeU-MSea •* j^-^jI.; i. "i/< ^. >•• , . •GrantP^ghin^publish^ 8urface. H»<pamphlets, aimed »t?th* Mndo «f n»ff.;} :. hkely to get.the bends and perhapstakes that-sport divers niay make. This'' even; an air embolism in his,-bloodpamphletVcounterlUthe...dangerous;^ stream. ^^^''0mysUque. associatedJwith" deep dives ^ ™ i, • ; .vVri'v.that' can induce divers to 'take 'risks,'.'overextend their skills, and take their'bodies toMhe limits'pof -physiological,capacity., -:. ^;gyxo5- *tgg}^i£jgf'

The bends.are^a' consequence ofrapid decompression-in which nitrb-

>gen gas,- normally- present in the,^5'- •^bloodstream and present at elevated^'^'^Xlevels when-the;body is under.pres-

vVsure, forms bubbles in the blood just... as soda pop forms gas bubbles when a;' bottle is opened. A serious case of•'_ bends can cause death within fifteen

minutes, and-even a minor case canbe agonizing. Rapid ascent to the surface may also result in the formationof an air embolus in the bloodstream. The lungs, which are filledwith air at deep-water pressures, mayexpand greatly as external pressuredrops during the ascent to the surface. Lung tissues may rupture aslung volume expands, and an air bubble may enter the blood. The bubble

RESEARCH NEWS /1?

may travel to the brain and get stuck*there, blocking circulation and causing symptoms like those of a stroke.Sometimes the effects of an air embolus are transitory, like somestrokes, but other times the effectmay be death, particularly if thediver loses consciousness before surfacing.

One of Sea Grant's roles is toprovide information about divingsafety and diving techniques. ThusSomers has put out a number ofpublications: the Diving SafetyBulletin, the Research Diver'sManual, The Complete Guide toCave Diving published by theNational Association of UnderwaterInstructors, and Cold Weather andUnder Ice Scuba Diving. To complement, these publications, Somers actively, promotes safety amongrecreationalidivers by traveling aboutthe state and meeting frequently withsport divers: While reminding diversofthe potential dangers they face, healso learns': from them-'about" newcommon problems and changing attitudes. •..,w". . .>Inone region of the country legisla

tion has recently been proposed .thatWQuld-closelyregulate cthe ^activitieso£ sportdivers.,The matter.has arous-ed'intense interest in the diving community/-The legislation rvis controversial (nsofar as it aims:primarily atprotecting the diver jfrom himself.Somers feels.-that education andtraining, ;not laws, wiUNbesthelp thediver,protect himself. Few"aspects ofdiving, .he. believes, lend themselvestoulegal regulation.rHe. hopes thatlegislation can be avoided at least until, it can be shown that divers are

jeopardizing some legitimate publicinterest. In the meantime, the improving safety record of diverssuggests that the self-regulating practice of the diving community is adequate to the needs both of divers andthe public. As a member of the boardof directors of the National Association of Underwater Instructors.Somers is in a good position to influence educational programs andpolicies that will help enhance thesport diver's safety without crampinghis pleasure in the sport.

20/ RESEARCH NEWS

Underwater Medicine10*

When humans venture into anunaccustomed realm, they often takephysicians along with them. Ships'surgeons are an old tradition. Flightmedicine was an innovation ofthe Second World War. Today, just as thespace program depends upon medicalspecialists to predict, monitor, andovercome the physical changes andproblems that are met in a new environment, so too does the U-Mmarine biology group, have twophysicians who accompany them andwho are involved.with the medicalaspects of a high pressure environment. Martin J. Nemiroff, M.D.,Assistant Professor of InternalMedicine and staff member of thePulmonary Division of the Departmentof Internal MeSicine, and JohnW. Dircks, M.D., Fellow in InternalMedicine, have made house calls atthe Hydro-Lab and are doing medical studies based on their'experiencewith-the human body'at elevatedpressures. .-":'{• ' -;;;-•:--

The basis of Nemiroffs and Dircks'involvement with the Hydro-Labresearch team is simply the requirement trmtajphysiciari beon calluiuV;^ing§peri&s&p& compression fand-deoompression.i'Nemiroff in 1973andDircks in 1974 both stood by at theHydro-Lab shore station to provideadvice, to serve in^mergencies/andto perform'check-ups• on the divers.Both'are accredited divers who, allduringthe two saturation dives;stoodready to dive within one minute ofanemergency call or else to transport adiver who had suddenly surfaced to aland-based hyperbaric chamber inwhich he could be repressurized. Anemergency that might have forcedone of the divers to flee for the surface would have given rise to explosive decompression sickness andcreated a ,fifteen-minute life-and-death crisis'. In the eight minutesavailable before the diver's bloodbegan to fill with bubbles like shakensoda pop he would have to be movedto the hyperbaric chamber. Not to re-pressurize the diver within fifteenminutes would mean his death.

The physicians are also interestedin other medical aspects of diving.Mindful of the long-term bonemaladies that some divers have suffered, Nemiroff and Dircks ordered x-rays of the divers' longbones in orderto get base-line information on bonecondition before they dove. The bonenecrosis (tissue death) that hasafflicted some divers is poorlyunderstood and requires basic research; itmay be causedor influenced by rapidcompression of the body or by inadequate decompression.

gradually released from the chamberwhile the patient is treated, if necessary, with oxygen or medications andbrought back to normal. A physiciancan work inside the chamber to carefor a patient and can move in and outthrough the air lock, which permitsconstant pressure to be maintained inthe inner lock.

The hyperbaric chamber was initiated by Somers, who purchased itthrough the Sea Grant Program. It isavailable for special medical treatments as well as for recompressing

,\.;You.never enjoy the world aright, till the seaitself floweth in your veins. Z:-w.-'.I.. *::vi.•'•£

Thomas Traherne, Cextnries of Meditation %K

^During a dive, researchers may,though only rarely, need medical

:attention for animal stings or shark orbarracuda bites. ^The warm humidconditions inside Hydro-Lab can alsocreate a fungus growthon the skin, a

-'kindtof wildly-spreading .athlete's;tfootkSuch a'condition requires rthe•"' careful applicatibnjpfpowerful fungi

cides and may force a diver to' interrupt his saturation dive for surfacetreatment. Nemiroff also emphasizesthe importance of someone's keepinga detached eye on the psychologicalcondition of divers, who are coopedup--in an unusual and physicallystressful environment for severaldays, yet who are more thanusuallydependent on alert faculties andrational thinking.

Dircks and Nemiroff share responsibility with Lee H. Somers for thetreatment of diving emergencies in aspecial Ann Arbor facility, a hyperbaric chamber in the UnderwaterTechnology Laboratory. The hyperbaric chamber is a large tank inwhich pressure can be raised to a level(equivalent to 292 feet of oceandepth) that will restore toequilibrium an explosively decompressed or endangered diver. Over aperiod of hours the pressure can be

divingaccident victims! Police agencies and; physicians throughout thestate .know aboutthe -chamber andcartjquickly arrange to, have diverstransported -toi ^Ann^ Arbor :byhehobpter. for emergency'treatmentThej'̂ wth^of'sport-.'diving.JiasfostCTBttlbet^n^eMiy1972'and late1974^^^b^^requiring 224hoursofhyperbaric therapy.

High air pressure and high oxygenpressure that the hyperbaric chamber provides are useful to non-diversas well asi divers. Patients with gangrenous"infections can. benefit because the high pressure oxygen makesan abundance of oxygen available toaffected'tissues: oxygen diffusesrapidly and deeply into tissues, turning'living flesh pink and revivifyingit. Dead tissue remains discoloredand is easily distinguished from theliving. Surgeons can see quickly howmuch tissue must be amputated andhow much can be saved. They neednot cut away any tissue whose condition under normal atmosphericpressure might appear ambiguous.

The chamber also helped save thelife of a victim of carbon monoxidepoisioning. The victim, comatose andvomiting when discovered, mighthave choked to death or died from the

Lee H. Somers at the controls of thehyperbaric chamber in the Underwater Technology Laboratory. He cancommunicate with a diver undergoing

recompression treatment or with aphysician, here Dr. Howard Nemiroff,who may also be inside attending to apatient.

RESEARCH NEWS/21

gas. Under high pressure andbreathing pure oxygen the victim regained consciousness immediatelyand made a full recovery. In such acase the high-pressure oxygen diffused through the lungs and dissolved directly in the blood plasma. Itskirted the hemoglobin molecules,which were already chemicallyclogged with carbon monoxide, andmoved directly in solution to supplythe brain with the vital element. After one hour in the chamber, the carbon monoxide gradually diffused outof the victim's red cells through thelungs, allowing a return to normal gasexchange.

The hyperbaric facilities also include two-chambers that are not usedfor medical treatments. One, whichcan achieve pressures up to theequivalent of 800 feet of sea water,was recently brought to campus fromthe former Willow Run Laboratoriesand will soon be used forsome physiological and engineering studies. Theother, acquired from the U-M Medical Center, is small and useful forstudies not involving human subjects.

Somers uses the hyperbaric chambers for technological andv physiological studies. In the small chamberhe tests and evaluates the researchdiving equipment that he and otherU-M researchers use. The chambersare also used by students who gettraining in their operation. Suchtraining is becoming increasingly useful as industrial diving, often in pursuit of mineral resources, grows in importance. Diving safety requires thata surface recompression facility beavailable wherever persons are atwork under water. Somers andNemiroff have written a hyperbaricchamber attendant's handbook,which covers both the technicalaspects of chamber maintenance andoperation and the medical procedures for which the chamber isused.

Somers also plans to use the largenon-medical chamber to test humanperformance under the pressures thatare experienced by the sport diver.Much is known, particularly throughthe research of the United States

22 / RESEARCH NEWS

Navy, about the physiological experience of the fit and trained diver,but less is known about what happens to the body of the relatively unconditioned amateur diver—young,old, male, or female—who spends histime mainly in shallow dives. Suchdivers may soon number as many astwo million Americans, according toSomers, and they will all need soundadvice about what to expect and howto treattheirbodies before andduringa dive. In the.chamber Somers will beable to pressurize human subjectsand perform such tests as measurements of respiration, ventilation, andcardiovascular fitness. An example ofthe immediate utility of such studiesmight be an analysis of therespiratory fatigue associated withtightly fitting wet suits, which maycompound the difficulties of breathing under high pressures.

Nemiroffand Dircks use the hyperbaric chambers in a variety of research efforts. One of these aims atperfecting the diving tables that nowtell divers how much time they mustspend decompressing, and at whatdepth, after they havespent time under water. Small bubbles may formharmlessly in the blood during decompression, but they should beavoided if possible. Recentexperiencehas shown that suchbubbles mayoccur later in decompression than hadbeen thought. In order to arrive at"bubble-free"diving tables, Nemiroffand Dircks plan to use a sonar devicethat can measure, from outside thebody, the size of bubbles movingthrough the blood vessels and to testfor bubbles in a variety of decompression regimes. •

A project that the hyperbaricteamis still developing makes, use of thechamber and other facilities that areunique to the University of Michigan.They plan to study red bloodcellchanges under conditions of hyperbaric oxygen. The physicians are interested in elucidating the enzymes ofenergy production. By observinghowthese enzymes become altered underhigh pressure, they may find evidencepointing to the way in whichthey useenergy-rich molecules to perform lifefunctions.

Sometimes underwater investigatorsmay use surface-supplied diving gearrather than scuba. Air is pumped to thediver through the hose shown coiled on

Dircks, Nemiroff, and others arealso collaborating on a study of themetabolism of cancer cells, whichmultiply exceedingly fast underhyperbaric conditions: They willgrowcultures of cancerous tissues andtreat them with certain chemothera-peutic agents, which have theirgreatest effect against cancer cellsthat are reproducing. They hope tolearn whether the chemicals will attack cancer cells more vigorouslythan usual when the tissue cultures

the deck here. The Underwater ^Technology Laboratory is oftm used to -~test such gear before U-M invcstigaton'>use it under water.

have abundant oxygen to grow in.These -projects are all, in a sense,

spin-offs of the research program inmarine biology and the unierwaterprograms. Even without this research, the hyperbaric chamberwould still be saving live? and ensuringthe welfare of Michigandivers.Continued medical experience withhyperbaric conditions may in turnlead to the enhanced safety and productivity of the research diving activities.

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UR1, JNARRAGAHSEFT BAY C^FUSMARRAGANSETT* M 0288J

RESEARCH NEWS/23

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I seem to have been only a boy playing on thesea-shore, diverting myself in now and thenfinding a smoother pebble or a prettier shellthan ordinary, whilst the great ocean of truthlay all undiscovered before me.

Isaac Newton

RESEARCH-NEWS———Division of Research Development

and AdministrationThe University of MichiganAnn Arbor, Michigan 48104

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The Research News, in describing a different area ofscholarly activity each month, reflects the diversity ofcurrent research at The University of Michigan. The articlesare designed to be interesting and understandable to thenonspecialist. Current issues of the Research News, including multiple copies for educational purposes, areavailable at no charge. Back issues dating from 1952 canbe purchased from University Microfilms, 300 N. ZeebRoad, Ann Arbor, Michigan 48103. Correspondence concerning the Research Nev/s should be addressed to theEditorial Office, Division of Research Development and Administration, The University of Michigan, Ann Arbor,Michigan 48104.

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