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SCIENCEStrand.processes that shape the earth.processes of life.how living things interact with theirenvironment.the nature of science

Standards.understands the need for protection of thenatural systems on Earth.describes patterns of structure and functionin living things.understands the competitive, interdependent,cyclic nature of living things in the environment.understands that science, technology, andsociety are interwoven and interdependent

SOCIAL STUDIESStrand.people, places, and environments (Geography)

Standards.understands the world in spatial terms.understands the interactions of people andthe physical environment

IANGUAGE ARTSStrand.writing.listening, viewing, and speaking.language

Standards.writes to communicate ideas and informationeffectively.uses listening strategies effectively.uses speaking strategies effectively.understands the power of language

Aquacul1:ore can be defined as theraising of a(luatic organisms undercontrolled or semi-controlledconditions. It is similar to farming, onlyunderwater!

AmericaILs spend billions of dollarsimporting marine foods from around theworld. We inlported 80 million pounds ofBay Scallops from China last year. Thesescallops were started from 26 bayscallops ori~inally taken from the UIlitedStates and r,used using our aquaculturetechniques! .rust over thirty years ago wecould go rig]u out to Tampa Bay andcollect them ourselves. Now we pay toimport them from China! How did thishappen?

Scallops are catastrophic spawners,that is, wherl one scallop spawns they allfollow and you have one massivespawning. T1is occurs becausefertilization occurs in the water column,In order for eggs and sperm to meetthey have to be present at the sametime. Howev ~r, if conditions are notideal when ttle first scallop spawns andtriggers spa,vning in the rest of thepopulation, 1:he results may bedisastrous.

The majc,r factor determining theoccurrence (If the spawning eventseems to be a change in temperature.Unfortunately, even though thetemperature may be correct, somethingelse may be wrong. For instance, thetide may be going out, not in. The entirespawn from that population may be lost.However, th«~re are usually other

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D RO JECT

~ceano gr ap hy

700 eggs/cJn3. A mjxture of antibioticsmay then b,~ added. However, this bringswith it the ]Jroblem of tissue residues,toxic effect:) on the larvae and possiblybacterial re sistance. Other avenues ofpathogen a'10idance such as watertreatment and probiotics are beingstudied at lJSF. The water is replacedevery two days. When the larvae reachthe veliger stage they are sievedthrough a 150 micron screen andretained on a 20 micron screen. Theweakest swjmmers are usually discardedand the relI.ainder is kept in a tank wherethey are fed with phytoplankton. Thephytoplank10n are also raised at theaquaculture facility. They also must betreated witt. antibiotics so as not tointroduce a pathogen into the scallopculture. Currently, the hatchery at USF isusing two s;>ecies of phytoplankton,which the sc:ientists grow until thecultures reach the correct densityhopefully at the same time the scallopsare at the OJrrect life stage. They are fedtwice a day. The optimal way to feed thelarval scallops would be to feed them amjxed culture of phytoplanktoncontinuousl'v. The mjxed culture ensuresthey are get ting all of the nutrients thatthey require. A continuous feeding isbetter becalLse that is how a scallopfeeds, contiJlUously. It is a filter feederand it constantly filters the water for itsfood. The sc:ientists at the University ofSouth Florid a and Florida DEP arecurrently w(lrking on the development ofa cost efficient method for a continuous

populations around to reseed the lostpopulation, and all is not lost.Unfortunately, if the area is over-fishedor there is a high mortality due topollution there may not be sufficientstock to jump-start the population. Thenatural year to year fluctuation in larvalsurvival carries with it a greater cost inFlorida than it does in some of thecolder climes because the life span ofthe bay scallop in Florida is only aboutone year. If the spawn is lost, thepopulation is lost. These factors alongwith a possible loss of habitat mayhave brought about the demise of thebay scallop in Tampa Bay.

This brings us to 1998 on Floridawest coast. For example, Tampa Bayand other areas now have adequatewater quality. The bay scallop wouldstand a good chance of surviving herenow. However, there are no populationsnearby to spawn and reseed the area.We now have the power, usingaquaculture, to restore the bay scallopin Tampa Bay and in other areas alongthe Florida west coast.

We start the restoration process bycollecting scallops from wildpopulations. Spawning is induced bybringing about the correct temperature

.change (Fournier and Marsot, 1985). Thefertilized eggs are then placed in a100-1 Nalgene container at a density of

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the water co]umn. Care must be taken indeciding wh(~re to place the cagesbecause suit,ible food organisms mustbe present aJld the current regime mustbe correct. There must be adequateprotection from storms, and of coursethe salinity, 1 emperature and waterdepth must ctlso be just right! Frequentcleaning of both the nylon mesh bagsand the cage) is important. If barnacles,oysters and ,ilgae foul these devicesheavy mortality may occur. This isprobably because the scallops need aconstant flo~r of water from which tofilter their food.

feeding with a mixed phytoplanktonculture.

-;'~::'~T""-';"':-":"_'.""cc;'.:-""'-"":--"::'",;--,::,::::: :;.~~ SPORT ATION;; OF JUVENILES ,;;:

When the scallops reach thepediveliger stage after about 8 days,which is indicated by the presence of afoot and a bottom seeking behavior,the diet is reduced and the speciesmixture is changed. The scientists thenutilize either astro-turf or strips ofblack plastic (to mimic sea grasses) forthe larvae to settle upon. The settledspat are kept like this for about onemonth. They are now visible to thenaked eye and can be gently brushedoff of their plastic seagrass home intovery fine mesh nylon bags. Each ofthese mesh bags hold about 25 to 50thousand spat! The mesh bags can nowbe transferred to various nursery sites.There, they can be hung over seawallsor off docks. The scallops grow foranother 2 months to a size of about6-8 mm shell height.

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.: c::::.:: :.:c: .:::: ':C:'C::: .:c: ::c::: :::

At this time they can move into theirscallop condos! These condos areactually specially designed cages forthe scallops to live in. They can be hungfrom a raft (hanging culture) or they cansit on the sea floor, (bottom culture).The cages prevent predators frommunching on the scallops, yet they allowthe scallops to filter their food from

If money JS to be spent annually onthe restoraticill of the bay scallop then ithas to be prclven that in fact therestoration efforts are effective.Therefore a tlaseline population countmust first be made before any areas arerestocked. Tl:.e best way in which tocarry this Ou1: is by choosing sites thatwill be restoc ked and making initialscallop counts in this area and latercomparing this with counts made afterthe restocking has occurred. Transects(rope lines) are deployed and scubadivers swim illong the transects andcount the nwnber of scallops that theysee. They usually count 20 differenttransects at (~ach sites. The data shouldthen be anal} zed using appropriatestatistical m~ thods.

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The proportion of enhancedversus wild stock may also beassessed using genetic means. Theinitial population can be measuredgenetically. The scientists then isolate,find a unique genetic tag in thehatchery scallops. This genetic tagmay be later surveyed for usingnon-invasive techniques so as not todeplete the restocked population.

The bay s ::allop only lives aboutone year, the:~efore it has a shortproduction c~Tcle. Also, once it is in thenursery and J~ow-out stages, food issupplied by t:le natural phytoplanktonpopulation. 1herefore, most of thecost is incurr ~d by spawning,incubation, larval rearing andharvesting th ~ adductor muscle. Themeat yields f:~om cultured scallops areusually 1 0-15 ~ higher than those ofcomparably sized, wild scallops. Thereis already a nlarket for the bayscallop, the success of the Chinesebay scallop producers can attest tothat. Howeve]', the cost of labor ismuch lower ill China than it is in theUnited States The question is can thecosts of raisulg them locally offset theprice of shiPI'ing them into U.S.?

The intent of the restoration.project is to utilize .sto~k

enhancement to assIst illre-establishment of the wild scalloppopulation. In contrast the intent ofan industrial aquaculture project is toraise scallops strictly for commercialpurposes. That is, to keep themcaptive until they reach their maximumsize 60- 70m and then harvest themfor human consumption. Therestoration project will also bringmoney to the Florida west coast.Tourists used to flock to known bayscallop harvesting areas providingrevenue for area hotels, dive shops,fishing guides and restaurants. Theindustrial aquaculture projects willalso have an economic impactprovide jobs/steady income for theunemployed Florida fisherman on thewest coast.

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BRO]ECT~eano graphy

Discussion Questions Activities

1. Name two ways in which ascallop Inoves? (larve Inove ~thwater currents and ad~ts have jetprop~sion by rapidly opening andclosing its valves)

1. Label thE parts of a scallop. (seeteacher/stud~nt worksheet inset)

2. Scallop (:ook Off- each studentshould look for different scalloprecipes that they find in variouscook books or on the internet.Compare dif ferent uses for scallops.

2. How can you determine the topside of a scallop? ( Note growth ofalgae and fouling organisims on topside)

3. Have ~e students do a researchproject on ~ :caIlops. Some ideas are:3. What part of a scallop do

Americans eat? (Only muscle,Europeans eat whole animal) -the effects of pollution on the

scallop popLllation4. What does a scallop eat?(plankton) -the effect~ t of phytoplankton

blooms on 1 he scallop population5. What eats a scallop? (Starfish,carnivorous snails, stingrays andsome fish)

aquacultw ~e

life cycle6. How can you tell a male from afemale? (they are both male andfemale)

7. What Phylum is a scallop in?(Mollusca)

8. How long does a Bay Scalloplive? (two years)

9. Where does a scallop live?( seagrass beds)

10. Do scallops have a future inFlorida? (discuss habitat anddevelopment)

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