energy analysys and the coupling of man and estuaries

7/27/2019 Energy Analysys and the Coupling of Man and Estuaries

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Ene rgy Ana lysis and the Co upl ingof Man and Estuar iesHoward T . Odum, W . . Kemp, Maur ice Se l l,Walter Boynton* and M. Lehm anD e p a r t m e n t o f E n v i ro n m e n t a l E n g i n e e r i n g S c i e n c e sU n i v e r s i t y o f F l o r i d aG a i n e sv i l l e , F L . 3 2 6 1 1* H a l l o w i n g P o i n t F ie l d S t a ti o nC e n t e r f o r E n v i r o n m e n t a l a n d E s t u a r i n e S t u d i e sU n i v e r s i t y o f M a r y l a n dP r i n c e F r e d e r i c k , M D 2 0 6 7 8

A B S T R A C T / N e w c o n c e p t s a n d i n s i g ht s c o n c e r n i n g h u m a na n d n a t u r a l s y s t e m s i n t h e c o a s t a l z o n e a r e e m e r g i n g f r o mr e c e n t e n e r g y a n a l y s i s a n d s y n t h e s i s s t u d i e s . B y u s i n g n e wc o n c e p t s f o r m e a s u r i n g t h e q u a l it y o f e n e r g y , o n e c a n e x p r e s st h e w o r k o f e c o s y s t e m s a n d h u m a n e c o n o m i e s i n e q u i v a l e n t

t e rm s . F r o m e n e r g y m o d e l s a n d n e w e n e r g y q u a l it y e v a lu a -t io n s , o n e c a n l e a r n w h a t k i n d s o f c o a s t a l s y s t e m s m a x i m i z ep o w e r , a r e c o m p e t i t iv e , e c o n o m i c a l l y v it al, a n d l ik e l y t o h a v e as u r v iv a l a d v a n t a g e .E n e r g y a n a l y s i s a n d s y n t h e s i s i s a i d e d b y e n e r g y c i r c u itd i a g r a m s . M o d e l s o f t h e c o a s t a l z o n e t h a t e m p h a s i z e t h ec h a n g e i n e x t e r n a l d r i v i n g f u n c t i o n s r e l a t e d t o w o r l d e n e r g ys o u r c e s p r o v i d e i n s i g h t s a n d s o m e p r e d i c t i v e a b i l i t i e s t h a t a r en o t f o u n d in e c o n o m i c s t u d ie s , s i n c e m o n e y f lo w s a l o n e d o n o te v a l u a t e e x t e rn a l d r iv i n g e n e r g i e s , T h i s p a p e r s u g g e s t s f o u rp r o c e d u r e s f o r c o a s t a l p l a n n i n g : 1 ) c a l c u l a t i o n o f in v e s t m e n tr a t io in u n i t s o f e q u a l q u a l i t y to d e t e r m i n e w h i c h p r o j e c t s a r ee c o n o m i c i n a b r o a d s e n s e , 2 ) d e v e l o p m e n t o f e n e r g ys i g n a t u r e s f o r c o a s t a l e c o s y s t e m s , 3 ) d e t e r m i n a ti o n o f w h i c hi n te r f a c e e c o s y s t e m s d e v e l o p t h e b e s t e n e r g y f l ow s , a n d 4 )d e v e l o p m e n t o f r e g io n a l m o d e l s t h a t in c l u d e t h e m a i n f e a tu r e so f h u m a n a n d n a t u ra l e c o s y s t e m s .

E n e r g y Q u a l i t y E v a l u a t i o n s a n d t h eI n v e s t m e n t R a t io

I n t h i s s e ct i o n , w e d i s cu s s t h e t h e o r e t i c a l c o n c e p t s o fe n e r g y q u a l i ty a n d t h e i n v e s t m e n t ra t i o a n d g i v e e x a m -p l e s a n d c a s e s tu d i e s o f e n e r g y q u a l i ty c a l c u la t io n s .E n e r g y q u a l i ty t h e o r y p r o v i d e s a u s e f u l e m p i r i c a l w a y

o f t r a ck i n g h i d d e n e n e r g y c o n t r i b u t io n s in c o m p l e xw e b s . I t i s t h e p r i n c i p l e t h a t a l lo w s t h e f l o w o f e n e r g y t ob e u s e d t o e s t i m a t e a b i l it y t o d o w o r k . P h y s ic s c o u r s e sa r e o f t e n s t a r t e d w i t h th e s t a t e m e n t t h a t e n e r g y m e a -s u r e s t h e a b i li ty t o d o w o r k . I f o n e c o m p a r e s e n e r g i e s o ft h e s a m e t y p e , t h i s i s t r u e ; b u t i f o n e c o m p a r e s e n e r g i e so f d i f f e r e n t t y p e s , C a l o r i e s o f h e a t e q u i v a l e n t s d o n o tm e a s u r e a b i li t y t o d o w o r k . C a l o r i e s o f d i s p e r s e d , d e -g r a d e d h e a t c a n n o t d o a n y w o r k . C o n f u s i o n o v e r t h e re l -a t i v e a b i li t ie s o f s u n l i g h t , c o a l, w i n d , w a t e r , a n d o t h e re n e r g y s o u r c e s t o d o w o r k i s c l a r i f i e d b y e x p r e s s i n gt h e m a l l i n e q u i v a l e n t s o f t h e s a m e q u a l it y , s u c h a s c o a lequiva len t s (Kca lcE) or fos s i l fue l equiva len t s (Kca l~rE) ,w h i c h a r e u s e d in t h is p a p e r ( O d u m a n d O d u m , 1 9 76 ).

T h e f l o w o f e n e r g y i n c h a i n s o f i n c r e a s i n g q u a l i t y i s

KEY WORDS: Energy analysis, Estuar ies, Coastal ecosystems, Energyqual i ty evaluat ion, F lor ida regional studies, Ene rgy mod-els, Cou pl ing, Envi ronm ental impact an alysis

Env i ronmenta l Managem ent , Vo l. 1 No. 4 , pp . 2 97-3 159 Springer-Verlag, New York Inc. (1977)

s h o w n i n F i g u r e 1 . L o w q u a l i t y e n e r g y i n t h e f o r m o fs u n l ig h t , s h o w n o n t h'e le f t, i s t r a n s f o r m e d a n d c o n c e n -t r a t e d t h r o u g h s u c c e s s i v e s t a g e s t o h i g h q u a l i t y e n e r g yo n t h e r i g h t . I n t h is p r o c es s o f u p g r a d i n g ( w h e r e e n e r g yf lo w s a r e f r o m o n l y o n e k i n d o f lo w q u a l i ty s o u r c e ) s o m ee n e r g y i s d e g r a d e d a n d d i s p e r s e d i n u n u s a b l e f o r m .T h e e n e r g y s o d i s p e r s e d m e a s u r e s t h e w o r k o f u p g r a d -i n g i f t h e s y st em h a s b e e n u n d e r c o m p e t i t i o n a n d s el ec -t i o n f o r e f f e c t iv e c o n v e r s i o n a n d e l i m i n a t i o n o f w a st e . I tt a k e s m a n y C a l o r ie s o f d i l u t e e n e r g y t o f o r m o n e C a l o r i eo f c o n c e n t r a t e d e n e r g y , s u c h a s f o s si l f u e l o r e l e ct r ic i ty ,w h i c h is r e q u i r e d f o r c o m p l e x w o r k . I f c o m p e t i t i o n h a sp r o d u c e d t h e m o s t e f fe c t iv e c o n v e r s i o n p o s s ib l e, t h ew o r k o f u p g r a d i n g m e a s u r e s t h e i n c r e a s e d c o st o f s u c hc o n v e r s i o n . A n e x a m p l e i s t h e c o n v e r s i o n o f c o a l t o e le c -t r ic i ty , d u r i n g w h i c h 3 . 6 C a l o r ie s o f c o a l a r e r e q u i r e d ,d i r e c t l y o r i n d i r e c t l y t h r o u g h g o o d s a n d s e r v i c e s , t og e n e r a t e 1 C a lo r i e o f e l e ct r ic i ty . F o r i t s e n e r g y c o s t t o b ej u s t i f i e d as a c o n t r i b u t i o n t o a s y s te m ' s m a x i m u m p o w e r ,u p g r a d e d e n e r g y m u s t i n t e r a c t w i t h o t h e r p a r t s o f t h ee n e r g y n e t w o r k t o s ti m u l a t e a t l e as t a s m u c h e n e r g y i n -c o m e a s t h e e n e r g y u s e d i n t h e c o n v e r s i o n . H i g h q u a l i t ye n e r g y t h a t d o e s n o t i n t e r a c t t o a m p l i f y l o w q u a l i t ye n e r g y i s w a s t e d .F i g u r e 2 a s h o w s a g e n e r a l i z e d s c h e m e o f i n t e r a c t i o na n d e n e r g y c o n v e r s i o n , w h e r e I , th e f r e e o u t s id e e n e r g yf l o w , i s a m p l i f i e d b y t h e f e e d b a c k l o o p F t o g i v e g r o s so u t p u t P . T h e f i g u r e a l so g iv e s d e f i n i t i o n s o f n e t e n e r g yN a n d o t h e r r a ti o s t h a t c h a r a c te r i z e t h e e n e r g y c o n v e r -s i o n p r o c e s s ( O d u m , 1 9 7 6 ).

2 9 7


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" i n c r e o s i n of i t(o )

h e a t i n g ,w i n d v e g e t a t i o n , h ~c r o p s m i c r o b e s , I c a r n i v o r e s ,o r g o n l c I f o s s i l f u e l : l r n i n [matter I s e n i m e " I ' l ; ~ ; ; ; g i ' Y I - -

QUALITY, CALORIE COST c u l t u r e( b )

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(c)F ig . 1 , C h a r a ct e ri s ti c e n e r g y c h a i n s r e s u l ti n g f r o m m a x i m u mp o w e r w h e r e e n e r g y i s p r i m a r il y f r o m o n e s o u r c e o f l owq u a l it y . (a ) e n e r g y t r a n s f o r m a t i o n s : ( b ) p o w e r s p e c t r u m i n h e a te q u i v a l e n t s ; (c ) a r e a l v ie w o f e n e r g y c h a i n s w h e r e i n c o m i n ge n e r g y i s d i l u t e d i s p e r s e d l o w q u a l i t y s u n l i g h t .

Examples of Energy Qual i ty E v a l u a t i o n sTidal Energy. T o o b s e rv e t h e o r d e r s o f m a g n i t u d e f o r

d i f f e r e n t e n e r g y f lo w s , w e h a v e e s t i m a t e d i n F i g u r e 2 bt h e c o s t s o f c o n v e r s i o n f o r t i d a l e n e r g y a t L a R a n c e ,F r a n c e , w h e r e a 2 0 - f o o t t i d e d r i v e s a n e l e c t ri c p o w e r p l a n t .H e a t e q u i v a l e n t s o f e n e r g y f l o w s a r e c a l c u l a t e d f i rs t , i n -c l u d i n g t h o s e u s e d e l s e w h e re i n t h e e c o n o m y t o g e n e r -a t e p u r c h a s e d g o o d s a n d s e rv i c es . P u r c h a s e d g o o d s a n ds e r v i c e s a r e e x p r e s s e d i n c o a l e q u i v a l e n t C a l o r i e s( K c a l e E ) a n d w e r e e s t i m a t e d b y c o n v e r t i n g t h e i r d o l l a rc o s t s i n t o C a l o r i e s a t a r a t e o f 2 5 , 0 0 0 C a l o r i e s p e r d o l l a r.E l e c t r i c i t y i s c o n v e r t e d t o K c a lc E a t a r a t e o f 3 .6to 1 .

N e t e n e r g y w a s e s t i m a t e d b y s u b t r a c t in g f e e d b a c k o fp u r c h a s e d g o o d s a n d s e rv i ce s f r o m e l e c t ri c al o u t p u tw h e r e b o t h a r e i n c o a l e q u i v a l e n t s , o r f o s si l f u e l e q u i v a -l e n t s (F F E s) . N e t o u t p u t , c o m p a r e d w i t h C a l o r ie s o f t i da le n e r g y i n p u t , e x p r e s s e s t h e e n e r g y c o s t o f c o n v e r t i n g 1

P ; . . . . . ,_ ," _ N _ _ , ,

Energy Qu al i ty Ra t io = -~ in Fossi l Fuel Equivalentsin He at EquivalentsY i e l d R a t i o = F-"

F t in Fossi l FuelIn ves t m en t Rat io = E q u i v a l e n t sN e t E n e rg y N = P - F

Energy C ost o f Transformat ion = CF ig . 2a , E n e r g y d i a g r a m d e f i n i n g e n e r g y q u a l i t y r a t i o ,i n v e s t m e n t r a t io , n e t e n e r g y , a n d y i e ld r at i o .

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1 5 0E n e rg y Q u a l i t y F a c to r = - ~ - = 1 .7 C o l F F E / C a l T id e1 6 2Y ie ld Rat io = ~ = 13 .7

N e t E n er gy = 1 6 2 - 1 1 . 8 = 1 5 0 x l O l O C a l F F 'EF ig . 2b . E n e r g y f lo w s in c o n v e r t i n g t i d a l e n e r g y a t L a R a n c e ,F r a n c e , t o e l e c t ri c p o w e r w i t h c o n v e r s i o n o f e n e r g y f l o w s t of o s s i l f u e l e q u iv a le n t s ( F F E ) f o r c a lc u la t io n o f n e t e n e r g y ,i n v e s t m e n t r a t io , a n d y i e ld r a t io . F F E i s r o u g h l y i n t e r c h a n g e -a b le w i th c o a l e q u iv a le n t ( CE ) .


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C a l o r i e o f t i d a l e n e r g y t o 1 C a l o r i e C E . T h e r a t i o o f 1 .7C a l o r i e s C E g e n e r a t e d f o r e a c h C a l o r i e o f t i d a l e n e r g yg a i n e d i s t h e e n e r g y q u a l i ty f a c t o r . T i d a l e n e r g y o f t h i sh e i g h t i s h i g h e r q u a l i t y t h a n c o a l b u t n o t a s h i g h a s h y -d r o e l e c t r i c p o w e r b a s e d o n a c o n t i n u o u s r i v e r h e a dw h e r e t h e e n e r g y q u a l i t y f a c to r i s 0 .3 .

Marine Food Chains. T h e w e b s a n d f o o d c h a i n s o fe c o sy s te m s a r e e n e r g y c h a i n s a n d m a y b e e v a l u a t e d f o rt h e i r e n e r g y c o n v e r s i o n c o st s a n d e n e r g y q u a l it y . G i v e ni n F i g u r e 3 a r e e s t i m a t e s o f e n e r g y f lo w i n f o o d c h a i n s o ft h e s h a l l o w e s t u a r y a t C r y s t a l R i v e r , F l o r i d a ( K e m p , e ta l. , 1 9 7 5 ). T h e e n e r g y q u a l i ty v a lu e s r e p r e s e n t e d b ye n e r g y f lo w s i n t h e f i g u r e p l a c e a l g a l b i o m a s s w i t h w o o d ,d e t r i t u s a n d h e r b i v o r e s w i t h c o a l , a n d c a r n i v o r e s w i t he l e ct r ic i ty . I n F i g u r e 4 is t h e e n e r g y c h a i n f o r a b l u e - g r e e na l g a l m a t e c o s y s t e m t h a t g e n e r a t e s a n e l e c t r i c a l o u t p u td i r ec t ly ( A r m s t r o n g a n d O d u m , 1 9 63 ). H e r e t h e c o n v e r -s i o n o f s u n l i g h t is s im i l a r t o t h a t c a l c u l a t e d i n T a b l e 1 .

Fig. 3. Energy flows for the estuary at Crystal River, Florida,for es t imat ing the energ y qual ity of s tages in ma rine foo dchains.

Fig. 4. Energy f low and t rans form at ion in b lue -green a lgalmat ecosys tem f rom Arm s t rong and O dum (1963).B l u e G r e e n A l g a l M o t

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T ab le '1 E ne r gy qua l i t y r a t i os used i n t h i s s t udyEn erg y Ty p e Co a l Eq u iv a l en t s* Q u a l i t y * *(Kcal co a l p e r Kca l) Fac to r

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*Fossil fuel mined and stored at place of use**Reciprocalof coal equivalence actorYoung and O dum, 1974

E n e r g y q u a li ty e v a l u a t io n s o f f o o d c h a i n s c a n b e u s e di n j u d g i n g t h e v a l u e o f v a ri o u s o r g a n i s m s t h a t a r e h a r -v e s t e d o r o t h e r w i s e a f f e c t e d . T h e o r e t i c a l l y , o r g a n i s m sw i t h h i g h e r e n e r g y c o s ts ar e s o m e w h e r e p r o v i d i n g t h es y s t e m w i th g r e a t e r e n e r g y s e r v i c e s i n r e t u r n . T a b l e 1g i v e s r e p r e s e n t a t i v e v a l u e s o f e n e r g y e q u i v a l e n t s . I n t h el e f t c o l u m n , v a r i ou s e n e r g y t y p e s a r e e x p r e s s e d a s c o ale q u i v a l e n t s ( C E ); t h a t i s, b y t h e n u m b e r o f C a l o r i e s C Ep e r h e a t C a l or i e. T h e r i g h t - h a n d c o l u m n o f T a b l e 1s h o w s t h e h e a t C a l o ri e s n e e d e d t o m a k e 1 C E C a l o r ie .T h i s m e a s u r e o f e n e r g y r e p l a c e m e n t c o s t is c a l le d t h ee n e r g y q u a l i t y f a c t o r . T h e e n e r g y q u a l i t y f a c t o r s a r e am e a s u r e o f e n e r g y r e p l a c e m e n t c o st a n d a r e p o s t u l a t e dt o b e a m e a s u r e o f a b i li ty to c o n t r i b u t e u s e f u l w o r k t os y s t e m s .P r in c ip le o f H ig h Qu a l i t y - L o w Qu a l i t y In t e r a c t io n

A c c o r d i n g t o t h e p r i n c i p l e o f m a x i m u m p o w e r( O d u m a n d P i n k e r t o n , 1 95 5) , s y s t em s th a t d e v e l o ps t r u c t u r e s t o i n t e r a c t h i g h q u a l i ty e n e r g y w i t h l o w q u a l -

i ty e n e r g y u t il iz e t h e h i g h q u a l i ty t o a m p l i f y t h e l o wq u a l i ty f l o w s s o t h a t m o r e w o r k i s d o n e b y b o t h . T h ep o i n t is m a d e b y s k e t c h e s i n F i g u r e 5 f o r t w o f lo w s .

T h e r e a r e i m p o r t a n t c o r o ll a ri e s o f th is t h e o r y . I fm a x i m u m p o w e r r e q u i r e s h ig h a n d l o w q u a li ty e n e r g yi n t e r a c t i o n , e i t h e r o n e c a n b e l i m i t i n g to t h e o t h e r .W h e n t h e r e i s o n l y lo w q u a l it y e n e r g y i t d e v e l o p s a c h a i no f e n e r g y t r a n s f o r m a t i o n s t h a t g e n e r a t e s s o m e h i g hq u a li ty e n e r g y t h a t c a n f e e d b a c k a s s h o w n i n t h e g e n -e r a l e n e r g y c h a i n o f F i g u r e l a . A l t h o u g h e n e r g y q u a li tyf a c t o r s f o r c l a s se s o f e n e r g y f lo w a r e g i v e n i n T a b l e 1 ,t h e e x a c t v a lu e s m a y v a r y d e p e n d i n g o n t h e c o n c e n t r a -t io n s o f e n e r g y t h a t a r e i n te r a c t in g . T h e m o r e l i m i t in g af lo w , t h e h i g h e r t h e e n e r g y q u a l i ty f a c t o r i t h a s i n a n yp a r t i c u l a r i n t e r a c t io n s u c h a s t h e o n e s h o w n i n F i g u r e 5 .A l l t h e f lo w s h a v e t h e e n e r g y q u a l i t y v a lu e o f t h e c o m -m o n o u t p u t s i n c e e a c h i s e q u a l l y e s se n t i a l.

F ig . 5 . T h e p r o p e r t y o f lo w q u a li ty e n e r g y a t t r a c t i n g h i g hq u a li ty e n e r g y f o r m a x i m u m w o r k o f b o th . ( a) e n e r g yam p l i f i ca t i o n i n a sy s t em wi th o u t m o n ey ; (b ) en e rg y i n v es t -m e n t i n a s y s te m w h e r e m o n e y i s i n vo l v e d w i th t h e h i g h q u a l it ye n e r g y .

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I n v e s t m e n t R a t i oT h e p r i n c i p l e t h a t h i g h q u a l i t y e n e r g y n e e d s l o w

q u a l i t y e n e r g y t o a m p l i fy i t i n o r d e r t o g e n e r a t em a x i m u m w o r k p o t e n t i a l t a k e s a s p e c i a l f o r m i n t h ec o u p l i n g o f m a n ' s e c o n o m i c s y s t e m t o t h e f r e e w o r k o fn a t u r e b a s e d o n d i l u t e s o l a r e n e r g y . I n F i g u r e 5 , h. ig hq u a l i t y e n e r g y F is p u r c h a s e d a t p r i c e P 1, a n d i t i n t e r a c t sw i t h f r e e e n e r g y i n f l o w I . N o t i c e t h a t m o n e y c i r c u l a t e sa s a c o u n t e r c u r r e n t . P u r c h a s e s a n d s al es in v o l v e h u m a n sb u t d o n o t p a y f o r n a t u r a l e x t e r n a l i n p u t s . M o n e y i n -c o m e is o b t a i n e d f r o m t h e o u t p u t s al es o f g o o d s a n d s e r -v i ce s, a n d t h e p r i c e P , h a s t o b e a d j u s t e d s o th a t i n c o m e ,i n t h e l o n g r u n , a t l e a s t , e q u a l s e x p e n d i t u r e s . F o rg r o w t h , i n c o m e n e e d s t o e x c e e d m o n e y c o s ts o f t h ep u r c h a s e d i n f l o w s .

T h e s y s t e m t h a t h a s m o r e f r e e e n e r g y t o m a t c h a n di n t e r a c t w i t h p u r c h a s e d e n e r g y g e n e r a t e s m o r e w o r ka n d c a n s e l l i ts p r o d u c t s a t a l o w e r p r i c e . I n t h e p r i c e e x -p r e s s i o n s h o w n , t h e f lo w s I a n d F s h o u l d b e e x p r e s s e d i nu n i t s o f t h e s a m e e n e r g y q u a l i t y . T h e l a r g e r I i s t h el o w e r t h e p r i c e , P , , a n d t h e m o r e t h e s y s t e m c a p t u r e s t h em a r k e t i n c o m p e t i t i o n w i t h p r o d u c e r s h a v i n g s m a l l e r ,n a t u r a l f r e e f l o w s I . T h e i n v e s t m e n t r a t io is d e f i n e d a sF / I , w h e n b o t h a r e i n t h e s a m e e n e r g y q u a l i t y u n i t s .

I n t h e U n i t e d S t a t e s t h e r a t i o o f h i g h q u a l i t y p u r -c h a s e d e n e r g y t o n a t u r a l e n e r g y i s r o u g h l y 2 . 5 t o 1 ( F /I ) .I n v e s t m e n t s o f p u r c h a s e d e n e r g y a t a h i g h e r r a t io m a yb e e x p e c t e d t o b e le s s c o m p e t i t i v e . T h e r a t i o is c h a n g i n g ,h o w e v e r , a n d s o m e h i g h q u a l it y e n e r g y s y st e m s t h a t a r e

e c o n o m i c t o d a y w i l l b e c o m e l es s s o i n t h e f u t u r e . T h ew o r l d - w i d e a v e r a g e i s o n l y 0 . 3 t o 1 . L o w v a l u e s s u c h a st h e s e i n d ic a t e u n d e r d e v e l o p m e n t , a n d m a y at t ra c ta d d i t i o n a l i n v e s t m e n t e n e r g y .E n e r g e t i c V i a b i l i t y o f E n v i r o n m e n t a l P r o j e c t s

T h e i n v e s t m e n t ra t i o m e t h o d d i s t in g u i s h e s b e t w e e np r o j ec t s t h a t a r e e c o n o m i c a n d t h o s e t h a t a r e n o t . T r a d i -t i o n a l m o n e t a r y c o s t - b e n e f i t a n a l y si s m a k e s a p a r t i a l d i s-t i n c ti o n b u t d o e s n o t e v a l u a t e t h e m a t c h i n g o f p u r -c h a s e d w i t h n a t u r a l e n e r g y s o u rc e s. E x p e n d i t u r e s t h a t d on o t m a x i m i z e t h e m a t c h o f e n e r g i e s t o t h e s y s t em u s i n gt h e e n v i r o n m e n t a n d p u r c h a s e d e n e r g y i n p u t s w e ll d on o t c o m p e t e a n d w i ll f a il e c o n o m i c a l l y . C o n s e q u e n t l y ,m u c h w e l l -m e a n i n g e n v i r o n m e n t a l t e c h n ol o g y m a y t u r no u t t o b e e n e r g y - i n t e n s i v e a n d a p o o r e x p e n d i t u r e o f t h ec o n s e r v a t i o n d o ll a r. T h e i n v e s t m e n t ra t i o m e t h o d w a su s e d t o c o m p a r e a l t e r n a t i v e d e s i g n s t r a t e g i e s i n s e v e r a ls t u d i es , t h e m a i n p o i n t s o f w h i c h a r e p r e s e n t e d n e x t .Cooling of Thermal D ischarges of P ower Plant . T h e i n -v e s t m e n t r a t i o p r i n c i p l e w a s u s e d t o e v a l u a t e w a t e r c o o l-i n g a l t e r n a t i v e s a n d i m p a c t s o n t h e e s t u a r i n e e n v i r o n -m e n t a t C r y s t a l R iv e r , F l o r id a . A f t e r 6 y e a r s o f r e g u l a ro p e r a t i o n , t h e p r o d u c t i v i t y o f s o m e 1 6 0 a c r e s o f t h e e s-t u a r y h a d b e e n d e c r e a s e d b y a b o u t 5 0 p e r c e n t d u e t o it sFig. 6, In te rac t ion ofes tua r ine cool ing with the rmal e f f luentan d the a l ternat ive of a cool ing tower. D ata from Crystal River ,Fla. (Odum et al., 1975).

1 0 9 F o s s i l F u e l E q u i v o l e n t s

I E stu or,n e~'~ C ,oice I c o ~ ~ - < l~ E n e r - < ~ i e s } ' - - - - f E c o s y s t e m ) /m " . . . . . l ,~ T o !! ! r r,1 = l ' " . . . . . ; ' . . . . . . . . . - - . . . . . . . - I , :IS t r e s s o fE s t u o r i n eC o o l i n g

2 7 6I n v e s tm e n t R o t i o o f C o o l in g T o w e r = " ~


6/19

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F i g . 7 , Use o f invested high qual ity en ergies fo r ter t iary wastet rea tm ent i n i n t e rac t ion wi th env i ronm ent (Mi tsch, 1975) . (a )in eut rop hic lake fol lowed by gro un dw ater injec t ion, (b) incypress sw amp; (c) by technology only. No te tha t in (c) noinve stm ent ra t io could be ca lcula ted because ther e was noma tch ing wi th na tu ra l ene rg i e s .

r e c e iv i n g d is c h a r g e w a t e r f r o m a o n c e - t h r o u g h c o o l i n gs y s t e m . T h e e n e r g y i m p a c t o f t h i s l o s s , i n f o s s i l f u e le q u i v a le n t s , w a s c o m p a r e d w i t h t h e e n e r g y r e q u i r e d f o rc o o l i n g t o w e r s , w h i c h w o u l d c o s t a n e s t i m a t e d $ 1 7 m i l -l i o n p e r y e a r ( F ig . 6 ). T h e e n e r g y n e e d e d t o e li m i n a t e t h ep o w e r p l a n t i m p a c t w a s va s tl y g r e a t e r ( 1 0 0 t o 1 ) t h a n t h ee n e r g y l o ss t h r o u g h i m p a i r e d p r o d u c t i v it y a t th e p o w e rp l a n t s it e ( S m i t h , 1 9 7 6 ; M c K e l l a r , 1 9 7 5 ) .

I n m a k i n g t h i s e s t i m a t e , w e a s s u m e d 2 5 , 0 0 0 C a l o r ie so f e n e r g y f o r e a c h d o l l ar . F o r t y p e r c e n t o f t h e 2 5 , 0 00C a l o r i e s i s t a k e n t o h e t h e h i d d e n , f r e e c o n t r i b u t i o n t ot h e U . S . e c o n o m y o f s o l a r - b a s e d n a t u r a l i n p u t s . A tC r y s t a l R iv e r , F l o r i d a , t h e l o a d o f t h e c o o l i n g t o w e r o nt h e e n v i r o n m e n t e l s e w h e r e w a s g r e a t e r t h a n t h e l o ca l e s-t u a r i n e i m p a c t.Waste Treatment and Na tural Recycl ing. F i g u r e 7 f r o mM i t s c h ( 1 9 7 5 ) s h o w s e n e r g y a n a l y s e s o f t r e a t e d s e w a g ew a s te p r o c e s si n g . T h e i n v e s t m e n t r a t io m e t h o d w a s u s e dt o c o m p a r e t h r e e a l t e r n a t i v e s : a ) d i s p o s a l i n a l a k e f o l -l o w e d b y g r o u n d w a t e r i n j e c t i o n (F ig . 7 a ), b ) d is p o s a l i ne x p e r i m e n t a l c y p r e s s s w a m p s ( F i g . 7 b ) , a n d c ) t e r t i a r yt r e a t m e n t b y t e c h n o l o g i c a l m e a n s ( F i g . 7 c ) . T e r t i a r yt r e a t m e n t , w i t h a l m o s t n o w o r k d o n e b y th e e n v i r o n -m e n t , p r o v e d t o o g r e a t a n e x p e n d i t u r e o f f o ss il f u el s,d i r e c tl y a n d i n d i r e c t ly , t o b e e c o n o m i c .Coastal Fishery. T h e s t ep w i s e a d d i t i o n o f e n e r g y i n -v e s t m e n t s i s i l l u s t r a te d i n F i g u r e 8 b y a n a n a ly s i s o f o y s -t e r sa le s f r o m F r a n k l i n C o u n t y , F l o r id a ( B o y n t o n ,1 9 7 5 ) . T h e f i g u r e s h o w s e n e r g y a d d e d a s o y s t e r s w h i c ha r e g r o w n , c a u g h t , p r o c e s s e d , u p g r a d e d i n p a c k a g i n ga n d a v a i l a b i l i t y , a n d f i n a l l y s e r v e d a s f o o d . T h e i n v e s t -m e n t r a t i o i s 2 . 1 t o 1 , c o n s i d e r i n g a l l f l o w s , w h i c h i s n o tf a r f r o m 2 . 5 to 1 , w h i c h i s t h e n a t i o n a l a v e ra g e . M u c h o ft h e e n e r g y i s a d d e d o u t s i d e F r a n k l i n C o u n t y . A s e n e r g yb e c o m e s l e s s a v a i l a b l e , h i g h q u a l i t y p a c k a g i n g w i l l b e l e s sc o m m o n , a n d f i s h e r y p r o d u c t s w i l l b e u s e d m o r e o f t e nl o ca ll y, w i t h le s s p r e p a r a t i o n . U s i n g t h e i n v e s t m e n t r a t i oo n e c o u l d predict t h a t s o m e a q u a c u l t u r e p r o p o s i t i o n st h a t h a v e v e r y h i g h r at io s o f p u r c h a s e d t o n a t u r a le n e r g y w i ll b e u n e c o n o m i c , b e f o r e t h e b a d m a t c h i sf o u n d t h e h a r d w a y .Hou sing D ensity in Coastal Areas. T h e i n v e s t m e n t ra t ioh a s a ls o b e e n u s e d t o e v a lu a t e h o u s i n g d e v e l o p m e n t s i nt h e c o a s t a l z o n e . H i g h h o u s i n g d e n s i t i e s i n v o l v e l a r g eq u a n t i t i e s o f p u r c h a s e d f o ss il f u e l e n e r g y w i t h le s sm a t c h i n g o f t h e f r ee e n v i r o n m e n t in t h e h i d d e n w o r k o fv e g e t a t i o n , w i n d , w a t e r s , s o i l s , r e c r e a t i o n p o t e n t i a l s ,s c en i c b e a u t y , n o i s e a b a t e m e n t , w a s te a b s o r p t i o n ,g r o u n d w a t e r s u p p l i e s a n d t h e l ik e . C a l c u l a t i o n s b y S te l-l a r ( 1 9 7 5 ) a n d B o y n t o n ( 1 9 7 5 ) f o r h o u s i n g d e v e l -o p m e n t s i n F l o r i d a s h o w e d t h a t p r o p o s e d p l a n s w e r e


7/19

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HEAT EQUVALENTSOTHER D OUTSIDECO0 S FUE LS ANO ECONOMYTAX FR AN K LIN OUNTY ~ SERVK:~ES 'SOURCES . T I0 GOODS'- I ~ , ~ . ~ x , o ' ~ . ) ~"~. AND9

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(b )Fig. 8. Inte ract io n of f ishery prod ucts with foss il fuel basedenerg ies of h igh qua li ty a t t rac ted , purchased , and inves ted bythe f ree n a tura l pr odu c t (Boynton , 1975) . (a) hea t equiva len tuni ts , (b) foss il fuel eq uivalents with inves tm ent ra tio.

s a t is f a c to r y o n l y i f b u i l d i n g s w e r e d i s p e r s e d s o t h a t t h eo v e r a ll i n v e s t m e n t r a t i o w as k e p t r e a s o n a b l e . T h e f u l l ,p r o p o s e d d e v e l o p m e n t o f c o n d o m i n i u m s a n d t h ea c c o m p a n y i n g p o p u l a t i o n d e n s i t y w o u l d h a v e h a d v e r yh i g h i n v e s t m e n t r a t io s .Feedback Reward Loop to Natural Systems

O d u m . ( 1 9 6 7 ) h a s d i sc u s s e d t h e p r i n c i p l e t h a t a n y s ys -t e m o f n a t u r e m u s t , i n o r d e r t o r e m a i n c o m p e t i ti v e , fe e db a c k e n e r g y t o i t s s o u r c e s y s t e m i n a m o u n t s a t l e a s te q u a l t o t h a t d r a i n e d a w ay . T h i s c o n c e p t is sh o w n i n th el o o p p a t h w a y i n F i g u r e 9 . I n e x p l o i t i n g w i ld f i sh e r i e s,m a n h a s h a r v e s t e d s p e c i e s w i t h o u t m a k i n g t h i s f e e d -b a c k . T h e r e h a v e b e e n e x c e p t i o n s s u c h a s o y s t e r l e a s e s ,a r ti f ic i a l r e e f s , a n d n u r s e r y f la ts . B u t w e h a v e o p e r a t e dg e n e r a ll y o n t h e o r i e s o f o p t i m u m c a t c h b a se d o n p o p u -

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d o m i n a n t u n t i l i t i s p u t o n e q u a l q u a l it y b a si s , a n d t h e n i ti s l e s s i m p o r t a n t ,D e v e l o p in g e n e r g y s i g n a tu r e s o f e n v i r o n m e n t s a n d o fc h a r a c t e r i s t i c sy s t e m s s h o u l d h e l p w i t h a v e r y o l d g e n -e r a l e c o l o g ic a l o b j e c t iv e ( p r e d i c t i n g e c o s y s t e m s t h a t r e -s u l t f r o m k n o w n e n v i r o n m e n t a l fa c to r s) . T h i s g r o u p o fe n v i r o n m e n t a l f a c t o r s h a s s o m e t i m e s b e e n c a l l e d t h e

b i o t o p e .I n t e r f a c e E c o s y s t e m s

B e t w e e n h u m a n a c ti v it ie s a n d t h e n a t u r a l w o r l d o ft h e e s t u a r y , n e w e c o i o g i c a l s y s t e m s o f t e n d e v e $ o p b e -c a u s ~ o f s p e c i a l i n t e r a c t i o n s . T h e r e c y c l i n g o f w a s t e s

p u t s s tr e s s u p o n m a n y c o m p o n e n t s o f e s t u a r i n e ec o sy s -t e m s , b u t o t h e r s p e c ie s a d a p t t h e m s e l v e s to t h e n e wc o n d i t i o n s b y d e v e l o p i n g t h r o u g h t ri a l a n d e r r o r t h er e w a r d l o o p s t h a t g e n e r a t e n e w v a r i e t i e s o f e c o s y s t e m s .T h e s e w e c a l l i n t e r f a c e e c o sy s te m s . T h e y h a v e g r o w n u pi n e n v i r o n m e n t s a f f e ct e d b y s e w a g e, t h e r m a l e f f lu e n t s,p u l p l i q u o r s , a n d o t h e r w a s t e s .

A s a p r i n c i p l e i n c o a s t a l m a n a g e m e n t , w e s u g g e s t t h er e c o g n i t i o n a n d d o m e s t i c a t io n o f i n t e r f ac e e c o s y s te m s a sa w ay t o r e d u c e e n v i r o n m e n t a l im p a c t a n d s a ve m o n e y .A n e f f o r t w as m a d e t o i d e n t i f y a n d c a t e g o r i z e i n t e r f a c ee c o s y s t e m s i n a s u r v e y o f U . S . e s t u a r i e s m a d e i n 1 9 6 8( O d u m , C o p e l a n d , a n d M a c M a h a n , 1 9 7 4 ). S i nc e t h e n ,w e a n d o t h e r s h a v e a t te m p t e d t o d o m e s t i c a t e so m e o ft h e m s o t h e y c o u l d b e u s e d t o g o o d a d v a n t a g e . A t t h ev e r y l e a s t , n a t u r e ' s s e l f - d e s i g n s s h o u l d b e r e c o g n i z e d a su s e f u l e n t i t ie s ; t h e y c a n a l s o b e a d a p t e d c o n s c i o u s ly a n de x p li ci tl y to s e r v e t h e p u r p o s e s o f e n v i r o n m e n t a l m a n -a g e m e n t . F i g u r e 1 1 i s a g e n e r a l i z e d s c h e m e o f t h e i n t e r -f a ce f u n c t i o n . S o m e s p e c if ic e x a m p l e s a r e g i v e n n e x t .

F i g . 1 1 . Interface systems. (a) technological interface, (b)interface ecosystems.

n te rfa c e | ~ J / / ~


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Man/Estuaries 3 0 5

Treated Sewage in Marshes and Cypress SwampInterface SystemsEvidence that salt marshes operate satisfactorily andwith higher productivity under treated sewage condi-tions was obtained fr om a Sea Grant project at the Insti-

tute of Marine Sciences, University of North Carolina(Marshall, 1971). Sewage ponds in the marshes, some-what simulating estuarine recesses, were more produc-tive in their water pha ses, althou gh lower in diversity byhalf due to low oxygen conditions at night. The largemanuscript on this project is now ready for publication(H. T. Odum, E.J . Kuezler, A. B. Williams, J. Day, andW. Wood, 1976. Structure and function ing of estuarineecosystems expo sed to t reated sewage wastesunpublishedUniversity of Florida).

Anothe r project, support ed by the Rockefeller Foun-dation a nd the RANN Division, National Science Foun-dation, has been testing recycling of treated sewage incypress domes for the past two years (Odum and Ewel,1974). Tho usa nds of cypress domes in most counties ofFlorida act as natural water conservation systems. Theseself-contained areas of I to 50 acres can apparentl y ac-cept 1 to 3 inches of waste water per week withoutdifficulty, absorbing nutrients and microbes in theirnatural filterbeds and rech argin g grou nd waters slowly.

Fig. 12. Recycling treated sewage wastes into cypress dome inproject at Gainesville, Florida (Rockefeller Foundation andNational Science Foundation--RANN Division).Use of cypress domes may be p referab le to less control-lable release of wastes in salt mars hes (Fig. 12).Estuarine Cooling

An estuari ne cooling interface at the inne r bay, Crys-tal River, Florida, was stud ied by Smith (1976), Snedaker(1975), and others who f ound some special adaptations,such as higher productivity in winter and lower produ c-tivity in summer. There were some turbidities in thesewaters, but in the very shallow waters conside rable bot-tom vegetation was maintained. T he interface ecosystemthat developed here was more productive than mostmarine ecosystems, althou gh less produ ctive tha necosystems of some nearb y zones. Oyster reefs of the es-tuary, studied by Le hma n (1974), were fou nd viable andfunctioning in the heated discharge. Figure 13 fromLehman shows the model and Figure 14 the simulationused to consider the impact of temperature and otheraspects. The simulations agree with field observations inshowing productivity and decreas ed diversity.

The roles of intake and discharge canals from power


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F i g . 1 3 . Model of oyster reefs at Crystal River from Lehma n(1974],

F i g . 1 4 . Simulation of reef model in Fig. 13 for varyingseasonal temperature ranges. Note declines in biomass anddiversity at elevated temperatures .

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Fig.15. Canals and power plants at Crystal River, Florida.plants as interfac e ecosystems was studied by Kemp (Inpreparation). Their location between the estuary andthe power plant is shown in Figure 15. in Figure 16, an-nual mean values for flows in grams of major elements(carbon, oxygen, n itrogen) per m = per day and storagesin g/m= and spp./1000 individuals are provid ed for a)the intake and, b) the discharge canal ecosystems whichinterface power plant to estuary. It can be seen that thehotter, more turbid, swifter-flowing discharge canal hadgreat er benthic biomass but was less diverse than the in-take canal ecosystem. Annual mean gross communityprod uctio n of the two canal systems was about 41 per-cent gre ater than that o f the bay systems they displaced,but was 39 percent less productive than the salt marshecosystems eliminated by canal construction (Kemp, inpreparation).M a n g r o v e s a s In t e r f a c e E c o s y s t e m s

Mangroves are good interfaces between man's settle-ments on the coast and the open waters. The mangrov esact as a hurricane buffer, nursery, and nutrient buffer;they absor b and release energy with a stabilizing effect.

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( b ' , D I S C H A R G E C A N A L E C O S Y S T E M , TO T A L C O M M U N I T Y- - - - R E S P IR A T IO NFig.16. Evaluated energy diagram of" main components ofcanal ecosystems at Crystal River.Given in Figures 17-23 are simulations by Sell (In prep-aration) of mangrove models as they respond to nutri-ents, to hurricanes, and to defoliation. Thes e studies in-cluded measurements of growth, nutrient uptake, andregrowth following herbicide application. Results ofenergy models and simulations are consistent with ear-lier ideas about mangrov es and their coastal role.Figure 17 is a simplified model of the mangroveecosystem showing the interaction between mangrovebiomass, mangrove detritus, and nutrients. Solar radia-tion is the major energy source, and part of it is con-verted to organic matter through photosynthesis .Energy subsidies are nutrients made available throughrainfall, daily tidal exchange and fresh water runoff.Also, the tidal fluctuations act as an energy subsidy.


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308 Howard T. Odum, W. M. Kemp, Maurice Sell, Walter Boynton, M. Lehman

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F i g . 1 7 . ModetofmangrovegrowthinFlor idawithhurricanesand the effects of nutrients. Values are given for the pathwaysand compart ments and were from work done by Lugo andSnedaker (1973) and Carter et al. (1973).

Figure 18 shows the impact tha t migh t occur fro m al-tering the flow of nutrien ts into a mangrove community .Case I included the contrib ution from terre strial runoff,tidal exchange, a nd rainfall; Case II elim inated tidal ex-change; Case III eliminated terrestrial runoff; Case IVeliminated all but the nut rien t flux from rainfall. In eachsituation, mangrove biomass increased to a maximumlevel, but the final level was lower as nutrient sourceswere removed. The worst situation was the removal ofboth tidal exchange and terrestrial runoff. This wouldsuggest that the effects of dred gin g tidal creeks and im-pounding mangroves could be destructive to the man-groves. Bacon (1974) note d that in the Caroni Swamp of

F i g . 1 8 . Effect on mangrove biomass of altering the nutri entflows into the mangrove ecosystem: Case I- -bo th terrestrialrunoff and tidal exchange contribute nutrients to the man-groves. Case II --t ida l nutrient cont ribution eliminated. CaseIII--ter restria t runoff nutrient contribution eliminated. CaseIV- -bo th tidal and terres trial nutrient contributions elimi-nated.

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I I I II 0 2 0 5 0 4 0 5 0N U M B E R OF Y E A R SF i g . 1 9 . E f fe c t o n m a n g r o v e b i o m a s s o f i n c re a s i n g t h en u t r i e n t flo w s f ro m t e r re s t ri a l r u n o f f : C a s e I - - n o r m a l n u -t r i e n t f l o w . C a s e I I - - f i f t y p e r c e n t g r e a t e r t h a n n o r m a ln u t r i e n t f l o w . C a s e I I I - - t w i c e n o r m a l n u t r i e n t f l o w . C a s eI V - - t h r e e t i m e s n o r m a l n u t r i e n t flo w .

T r i n i d a d t h e i so l a ti o n o f m a n g r o v e f o r e s t s f r o m f r e ew a t e r c i r c u l a t io n r e s u l t e d i n t h e d e a t h o f t h e s e f o re s t s.M a n g r o v e a r e a s c u t o f f f r o m f r e s h w a t e r in f lo w b u t n o tt id a l m o v e m e n t c o n t i n u e d t o f l o u ri s h .

F i g u r e 1 9 s h o w s f o u r r a t e s o f te r r e st r i a l n u t r i e n t f l u xh o l d i n g n u t r i e n t f l u x f r o m r a i n fa l l a n d t id a l e x c h a n g ec o n s t a n t. A s t h e n u t r i e n t i n p u t f r o m l a n d s o u r c e s - -m u n i c i p a l i ti e s , i n d u s t r y , a n d a g r i c u l t u r e - - i s i n c r e a s e d( C a se I t h r o u g h C a s e I V ) , m a n g r o v e s a r e s h o w n t o h a v e

h i g h e r b i o m a s s l ev e ls . E v e n t h o u g h t h e r e i s a n i n c r e a s e du p t a k e b y t h e e c o s y s t e m , t h e l ev e l o f n u t r i e n t s i n t h e e s -t u a r y h a s a l so i n c r e a s e d .

A n i n f r e q u e n t h i g h e n e r g y s t r e ss o n t h e m a n g r o v ee c o s y s t e m is t h e h u r r i c a n e . A m a j o r h u r r i c a n e o c c u r sa l o n g t h e m a n g r o v e c o a s tl i n es o f F l o r i d a a b o u t o n c ee v e r y 2 0 - 2 5 y e a rs . F i g u r e 2 0 s h o w s t h e i m p a c t o f a h u r -r i c a n e o n t h e m a n g r o v e f o r es t . I n t h i s f i g u r e o n l y o n eh u r r i c a n e w a s a l l ow e d t o s t re s s t h e m a n g r o v e s d u r i n gt h e 5 0 y e a r s t h e s i m u l a t i o n w a s r u n . C a s e I w a s f o r ah u r r i c a n e o f m o d e r a t e s t r e n g th , w i t h w i n d s p e e d s o fa b o u t 4 0 m e t e r s p e r s e c o n d ( 9 0 m i l e s p e r h o u r ) ; w h i l eC a s e II w a s fo r a m a j o r h u r r i c a n e , w i t h w i n d s p e e d s u pt o 9 0 m e t e r s p e r s e c o n d ( 2 0 0 m i l es p e r h o u r ) . T h e m o d -e r a t e h u r r i c a n e r e d u c e d m a n g r o v e b i o m a s s t o 9 0 0 0g r a m s c a r b o n p e r m s , a n d t h e r e c o v e r y t i m e t o a t t a i nm a x i m u m b i o m a s s le ve ls w a s a b o u t 1 6 y e ar s . T h e m a j o rh u r r i c a n e r e d u c e d m a n g r o v e b i o m a s s t o 3 0 0 0 g r a m sc a r b o n p e r m 2 , a n d t h e r e c o v e r y t i m e t o a t t a i nm a x i m u m b i o m a s s l ev e ls w a s 2 0 y e ar s . T h e l ev e l a f t e r

F i g . 2 0 . I m p a c t o f h u r r i c a n e s o n m a n g r o v e b i o m a s s . C a s eI - - r a o d e r a t e h u r r i c a n e . C a s e I I - - m a j o r h u r r i c a n e .

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310 Ho wa rd T. Odum , W. M. Kemp, M aurice Sell, Wa lter Boynton, M. Lehman

t h e m a j o r h u r r i c a n e w a s s l ig h t ly g r e a t e r t h a n t h em a x i m u m l ev e l w i t h o u t a n y h u r r i c a n e o c c u r r i n g . A c -c o r d i n g t o t h i s m o d e l , m a n g r o v e s m a y a t t a i n t h e i rg r e a t e s t b i o m a s s w h e n a 2 5 - y e a r c y c l e o f h u r r i c a n e s i sf o l l o w e d .Adaptat ion to Disorder ing Stresses

A k e y a s p e c t o f a n i n t e r f a c e e c o s y s t e m i s t h e s u b s t i t u -t i o n o f f a u n a s , f l o ra s , a n d g e n e r a l s t r u c t u r e o f e c o s y st e mr e l a t i o n s h i p s s o t h a t e n e r g y f l o w s t h a t w o u l d h a v e b e e n as t re s s b e c o m e u s e r s o f s tr e s s e n e r g y i n s te a d . M a r i n ee c o s y s t em s a r e a l r e a d y w e ll a d a p t e d f o r s t re s s es , s u c h a se x c e ss i ve t u r b u l e n c e a n d e x c h a n g e . B y s h i f t i n g t op l a n k t o n e c o s y s t e m s , t h e y u s e t h e e n e r g y o f s t i r r i n g t ok e e p s m a l l , l o w b i o m a s s p o p u l a t i o n s s t a b l e ( b y k e e p i n gg r o w t h c e n t e r s d i s p e rs e d ) t h u s s a v in g th e e n e r g y o f d e -

v e l o p i n g r o o t s, t r u n k s , a n d m a s s i v e b i o m a s s t h a t isf o u n d o n l a n d . I n t w o o f t h e s i m u l a t i o n s d o n e a t C r y s t alR i v e r b y S m i t h ( 1 9 7 6 ) a n d M c K e l l a r ( 1 9 7 5 ), t h e a d d i t i o no f f l u s h i n g a n d m i x i n g s t a b il iz e d t h e e v a l u a t e d m o d e l st h a t w e r e u n s t a b le b e fo r e . T h e s e m o d e l s a r e f u r t h e re v i d e n c e o f t h e r o le o f p o t e n ti a ll y d i s o r d e r i n g e n e r g i e si n a p o s i ti v e e n e r g y - s a v i n g r o l e .A n o t h e r e x a m p l e o f a d i s o r d e r i n g s t r es s e n e r g y i st h a t o f w i d e s p r e a d h e r b i c i d e s p r a y i n g i n V i e t n a m ,w h i c h r e s u l t e d i n d e s t r u c t i o n o f a s i g n i f ic a n t p a r t o f t h em a n g r o v e f o r e st a s s h o w n b y t h e m a p i n F i g u r e 2 1 . Fi g-u r e 2 2 is a m o d e l o f t h e m a n g r o v e e c o s y st e m i n S o u t hV i e t n a m , w h i c h i n c l u d e s t h e i n f l u e n c e o f h e r b i c i d e s ,w o o d c u t t i n g , a n d a l so s e e d s o u r c e s. F i g u r e 2 3 s h o w s t h er e c o v e r y o f t h e d e v a s t a t e d m a n g r o v e f o r e s ts a t t h en a t u r a l r a t e a n d a t tw o r a t e s o f p l a n t i n g b y m a n . N a t u r a l

Fig. 21. Defoliated zone in man-grove swamp so uth of Saigon inVietnam.


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Man/Estuaries 311

Seasonal S t imulus to Seedlings

~ Q n g r o v e sPho tosyn thes i s Metabolic Costs ~ / ~ Seedlings~ / Lost toMortality Sea

r e c o v e r y m a y b e a v e r y s lo w p r o c e s s, b u t w i t h s o m e h e l pf r o m m a n , r e c o v e r y t i m e c o u l d b e d e c r e a s e d c o n s i d e r -a b l y .Ecological Eng ineering

D o m e s t i c a t i o n o f i n t e r f a c e e c o s y s t e m s i s d o n e b y a d -j u s t i n g c o n d i t i o n s b e t w e e n m a n a n d n a t u r e . G u i d i n gs e l f - d e s ig n o f i n t e r f a c e e c o s y s t e m s i s o n e o f t h e t o o ls o fe c ol og ic e n g i n e e r i n g in w h i c h o n e u s es m o r e e n e r g i e so f n a t u r e a n d l es s e n e r g i e s o f te c h n o l o g y . T h e r e p e r -t o i r e o f k n o w n i n t e r f a c e e c o s y s t e m s is g r o w i n g , a n d i t i sn o w f e a s ib l e t o a s k o f p r o p o s e d p r o j e c t s : " H a v e y o u a r -r a n g e d c o n d i t i o n s so t h a t w a st es a n d i m p a c t s a r e k e p t i ns t e a d y f lo w to t h e e c o s y s t e m s t o w h i c h t h e y a r ea d a p t e d ? "Coasta l Zone Mode ls

A n o t h e r t o o l in c o a s ta l p l a n n i n g is e n e r g y a n a ly s is o na r e g i o n a l s c a le . I n a d o z e n r e c e n t p r o j e c t s ( T a b l e 2 ) r e -s e a r c h e r s h a v e c o n s t r u c t e d r e g i o n a l m o d e l s o f t h e c o a s-t a l z o n e i n v o l v i n g t h e e c o n o m i c s y s te m a n d v a r i o u sn a t u r a l c o m p o n e n t s o f th e e n v i r o n m e n t : e s t ua r ie s ,s w a m p s , a n d u p l a n d s . T h e c r it ic a l f e a t u r e o f m o s t m o d -e ls l i s te d i n T a b l e 2 is t h e w a y o u t s i d e d r i v i n g f u n c t i o n s

Fig. 22. M o d e l o f m a n g r o v e r e c o v er y i n V i e t n a m f r o mNational Academy of Science Report , Sel l (In preparat ion).a r e p r e s e n t e d s o t h a t t h e y sh o w t h e i m p a c t o f c h a n g i n ge n e r g y c o n d i t i o n s i n t h e w o r l d o n p r i c e s a n d l o c a le n e r g y a v a i l ab i li t ie s a n d u l t i m a t e l y o n t h e i n v e s t m e n tr a t i o . F i g u r e 2 4 s h o w s t h e s i m p l i f ie d e s se n c e o f d r i v i n gf u n c t i o n s a p p l i e d t o m o d e l s o f c o a s t a l F l o r i d a . W i t h o u te x c e p t i o n , t h e i n c r e a s i n g c o s t o f g e t t i n g e n e r g y l e a d s t o

F i g . 23 . Gra ph o f s imula ted recovery of the mo de l in F ig . 22 .

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energy analysys and the coupling of man and estuaries

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