Biomass as a Nonfossil Fuel Source - American Chemical Society

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Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on April 17, 2018 | https://pubs.acs.org Publication Date: January 29, 1981 | doi: 10.1021/bk-1981-0144.ch004

Biomass Production by Freshwater and Marine Macrophytes W. J. NORTH, V. A. GERARD, and J. S. KUWABARA W. M . Keck Engineering Laboratories, California Institute of Technology, Pasadena, C A 91125

Biomass plantations for energy production in coastal and oceanic settings have several inherent attractions. Water requirements for aquatic plants may pose no serious limitations. Algal tissues do not contain high proportions of refractory materials such as lignin and cellulose (which might complicate processes for conversion to certain fuels). Many algal species show little or no seasonal changes in potential for growth and presumably can be maintained indefinitely. Photosynthetic conversion efficiencies are good. Space is abundant in the oceanic environment and environmental energy in waves and currents might be utilized for tasks such as obtaining and dispersing plant nutrients. Research on aquatic macrophytes as producers of biomass has been undertaken at Woods Hole Oceanographic Institution (WHOI) on the east coast and on the west coast by a group of collaborators in a joint effort known as the Marine Biomass Project. Studies at WHOI have focused on estuarine and coastal situations with some attention recently to freshwater plants. The Marine Farm Project has primarily been concerned with oceanic biomass production. A group at WHOI led by John H. Ryther has undertaken a wide variety of studies concerning aquatic macrophytes including nutrient uptake, growth,

0097-6156/81/0144-0077$05.50/0 © 1981 American Chemical Society

Klass; Biomass as a Nonfossil Fuel Source ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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yields, a n d e n v i r o n m e n t a l factors a f f e c t i n g yields. Joel C. G o l d m a n of W H O I has s u r v e y e d a q u a t i c biomass p r o d u c t i o n s y s t e m s o n a w o r l d w i d e basis a n d is c u r r e n t l y e x a m i n i n g t h e role of c a r b o n as a p o t e n t i a l l i m i t i n g n u t r i e n t in b i o m a s s c u l t u r i n g . T h e M a r i n e Farm Project is presently a t t e m p t i n g t o g r o w g i a n t kelp in offshore w a t e r s off s o u t h e r n California. O t h e r w o r k related t o a q u a t i c b i o m a s s p r o d u c t i o n i n c l u d e s an i n v e s t i g a t i o n at t h e U n i v e r s i t y of California, Berkeley, of m i c r o a l g a e in p o n d s . This paper w i l l emphasize d i s c u s s i o n of t h e kelp p r o d u c t i o n phases of t h e M a r i n e Farm Project because of t h e a u t h o r s ' d i r e c t i n v o l v e m e n t t h e r e i n . W e w i l l also briefly s u m m a r i z e a c t i v i t i e s by t h e g r o u p s at W H O I . MACROCYSTIS BIOLOGY T w o species of Macrocystis o c c u r a l o n g t h e w e s t coast of t h e U n i t e d States f r o m Baja. California t o t h e Gulf of Alaska. M. pyrifera prefers t e m p e r a t e w a t e r s (ca. 5 ° t o 25°C) a n d requires s o m e p r o t e c t i o n f r o m severe w a v e s a n d s t o r m s f r o m central California n o r t h w a r d s . A d u l t plants t y p i c a l l y o c c u r in t h e d e p t h range 8 t o 2 0 - 3 0 m. This species does n o t usually o c c u r m u c h b e l o w 2 0 m in t u r b i d w a t e r . M. integrifolia o c c u r s a l o n g t h e n o r t h e r n p o r t i o n of t h e range, b u t is not i n c l u d e d in t h i s paper. The Macrocystis life c y c l e involves a h e t e r o m o r p h i c a l t e r n a t i o n of g e n e r a t i o n s b e t w e e n m i c r o s c o p i c - s i z e haploid g a m e t o p h y t e s a n d m a c r o s c o p i c d i p l o i d s p o r o p h y t e s (Figure I). Our p r i m a r y c o n c e r n is w i t h t h e large s p o r o p h y t e . T h e a d u l t s p o r o p h y t e is a n c h o r e d t o t h e b o t t o m by t h e perennial holdfast o r g a n . Unlike t r u e roots, holdfasts are n o t specialized for a c c u m u l a t i n g minerals. Macrocystis a n d indeed m o s t seaweeds a c c u m u l a t e t h e i r dissolved m i c r o n u t r i e n t s across all exposed surfaces. A s t e m l i k e p r i m a r y stipe e m e r g e s f r o m t h e holdfast apex and soon d i v i d e s into a c o m p l e x b r a n c h i n g p a t t e r n . A m o n g t h e first branches are blades t h a t p r o d u c e spores, a n d in N o r t h Pacific m a t e r i a l , these are t e r m e d s p o r o p h y l l s . T h e basal b r a n c h e s s u p p o r t a n y w h e r e f r o m one t o h u n d r e d s of fronds. T h e m a t u r e Macrocystis f r o n d consists of a long vinelike stipe s u b t e n d i n g gas f l o t a t i o n b u l b s ( p n e u m a t o c y s t s ) t h a t in t u r n s u p p o r t leaflike blades. A n older f r o n d m a y display a b o u t 2 0 0 or m o r e blades and p n e u m a t o c y s t s , dispersed in a regular p a t t e r n a l o n g t h e stipe l e n g t h . The u p p e r m o s t blade is m e r i s t e m a t i c a n d c o n t i n u a l l y p r o d u c e s n e w blades, p n e u m a t o c y s t s . a n d m o r e stipe. Basal m e r i s t e m s are sources of j u v e n i l e f r o n d s . The y o u n g f r o n d s d e v e l o p rapidly, usually r e a c h i n g t h e surface in t w o t o f o u r m o n t h s . The u p p e r p o r t i o n s of t h e m a t u r i n g f r o n d s t h e n b e g i n c o n t r i b u t i n g t o t h e c a n o p y . Frond lifespan is o n l y a b o u t six m o n t h s (J_. 3). C o n s e q u e n t l y , senescing f r o n d s m u s t c o n t i n u a l l y be replaced by p r o d u c t i o n of y o u n g f r o n d s g r o w i n g up f r o m b e n e a t h . Plants, as a w h o l e , m a y survive m a n y years (3).



Figure 1. Important phases in the life history of Macrocystis. Developmental patterns among the basal branches are shown in detail for the juvenile sporophyte to illustrate production of fronds and and of basal meristems.

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Dense Macrocystis canopies are able t o absorb 9 9 p e r c e n t or m o r e of s u n l i g h t e n t e r i n g t h e sea surface (4). T h u s j u v e n i l e f r o n d s exist in a d a r k e n e d e n v i r o n m e n t w h i c h has been s h o w n t o lie b e l o w t h e c o m p e n s a t i o n level [i.e. w h e r e p h o t o s y n t h e s i s balances respiration] (5, 6). L o b b a n (7) a n d Parker (8) d e m o n s t r a t e d existence of t r a n s l o c a t i o n processes in Macrocystis. Photos y n t h a t e p r o d u c e d in t h e Macrocystis c a n o p y is t r a n s l o c a t e d d o w n t h e stipes t o n o u r i s h j u v e n i l e f r o n d s . T h u s t h e s e y o u n g tissues are able t o g r o w rapidly, o v e r c o m i n g t h e self-shading p r o b l e m . T h e t r a n s l o c a t i o n c a p a b i l i t y enables Macrocystis t o f o r m very dense o p u l a t i o n s of h i g h biomass per u n i t area. T h e average s t a n d i n g c r o p of Macrocystis in s o u t h e r n a n d Baja, California is a r o u n d six f r o n d s per square m e t e r a n d c a n range u p t o t h i r t y fronde per square m e t e r (9). T h e average w e t w e i g h t of a f r o n d is a p p r o x i m a t e l y 1 t o 1.5 kg (10). N o r t h (JJJ s u m m a r i z e d results f r o m several e s t i m a t e s of p r o d u c t i v i t y in Macrocystis beds. Values r a n g e d f r o m 16 t o a b o u t 1 3 0 m e t r i c t o n s of d r y w e i g h t per hectare per year. Harvest yields, of course, are l o w e r b e c a u s e of inefficiencies in c u t t i n g a n d because o n l y u p p e r p o r t i o n s of p l a n t s ae r e m o v e d . T h e a n n u a l harvest f r o m California w a t e r s p r o v i d e s an average yield in t h e range of one t o t w o m e t r i c t o n s d r y w e i g h t per hectare per year. Values m a y be t w o t o f o u r t i m e s as h i g h for ore p r o d u c t i v e beds in areas w h e r e u p w e l l i n g is w e l l d e v e l o p e d . State l a w l i m i t s d e p t h of c u t t i n g by c o m m e r c i a l harvesters t o four feet b e l o w t h e surface. T h u s o n l y c a n o p y tissues are r e m o v e d . A l l apical m e r i s t e m s l y i n g w i t h i n t h e c a n o p y are also g a t h e r e d by harvesters. Hence t h e r e m a i n i n g p o r t i o n s of c u t f r o n d s c a n n o t s i g n i f i c a n t l y d e v e l o p further. T h e c a n o p y is essentially replaced f r o m g r o w t h by f r o n d s w h o s e apical m e r i s t e m s lie b e l o w t h e d e p t h of c u t t i n g . Usually, canopies regenerate in t w o t o f o u r m o n t h s so t h a t beds can be harvested t w o t o t h r e e t i m e s a n n u a l l y . Y o u n g Macrocystis plants m a y be raised f r o m t h e r e p r o d u c t i v e spores in t h e laboratory. A f t e r plants are 1 0 - 2 0 c m t a l l , t h e y can readily be t r a n s p l a n t e d t o t h e sea floor or t o artificial s t r u c t u r e s . T h e h o l d f a s t s are a t t a c h e d t o p r o j e c t i o n s by w i n d i n g r u b b e r b a n d s a r o u n d t h e m (12). A d u l t s m a y also be t r a n s p l a n t e d . T h e holdfast is first t h r e a d e d w i t h n y l o n line, t h e n p r i e d loose f r o m t h e b o t t o m , t h e p l a n t is m o v e d t o a n e w l o c a t i o n , a n d t h e h o l d f a s t is t h e n secured t o an a p p r o p r i a t e a n c h o r a g e (Figure II). A t t a c h m e n t t o solid s u b s t r a t e is n o t m a n d a t o r y . T h e holdfast c a n s i m p l y be m o o r e d by f a s t e n i n g it t o a rope. T r a n s p l a n t a t i o n t e c h n i q u e s are n o w used r o u t i n e l y by b i o l o g i s t s f r o m t h e State a n d f r o m t h e h a r v e s t i n g i n d u s t r y t o restore d e p l e t e d kelp beds in s o u t h e r n California.



Towing

Transplants ara shiftad ta •srmanantly

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Β. Transplanting Operation

Figure 2. One of several techniques in use for transplanting adult Macrocystis: A. details of kelp needle and its use to weave nylon line between hapteral clumps in the holdfast; B. operations involved in moving transplants to new location, using chain for towing


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EARLY STUDIES BY THE M A R I N E F A R M PROJECT Research o n oceanic f a r m s c o m m e n c e d in California a r o u n d 1 9 7 3 . T h e y w e r e m a n a g e d by t h e U.S. Navy, u n d e r t h e d i r e c t i o n of H o w a r d A. W i l c o x . A t a b o u t t h e s a m e t i m e , a g r o u p led by E d w a r d N. Hall at U n i t e d A i r c r a f t Research Laboratories in C o n n e c t i c u t w a s i n v e s t i g a t i n g m e t h a n e p r o d u c t i o n f r o m o r g a n i c materials a n d c o n s i d e r i n g t h e o r e t i c a l p r o b l e m s of m a r i n e biomass p r o d u c t i o n . In 1 9 7 6 , m a n a g e m e n t of t h e Navy p r o j e c t w a s a s s u m e d by General Electric C o m p a n y . T h e M a r i n e Farm Project c u r r e n t l y exists as a g r o u p of o r g a n i z a t i o n s g u i d e d by, or c o l l a b o r a t i n g w i t h , t h e General Electric g r o u p (Global M a r i n e D e v e l o p m e n t , Inc. — e n g i n e e r i n g ; I n s t i t u t e of Gas T e c h n o l o g y — m e t h a n e p r o d u c t i o n ; U.S. D e p a r t m e n t of A g r i c u l t u r e — kelp processing). T h e California I n s t i t u t e of T e c h n o l o g y has been separately f u n d e d by DOE b u t w o r k s in close c o l l a b o r a t i o n w i t h t h e General Electric part of t h e Project. Recently, responsibility for g o v e r n m e n t a l r e v i e w a n d m a n a g e m e n t w a s t r a n s f e r r e d f r o m DOE t o t h e Solar Energy Research Institute. A r e v i e w of t h e literature by J a c k s o n a n d N o r t h 0 3 ) e x a m i n e d c h a r a c t e r i s t i c s of n u m e r o u s s e a w e e d species t o i d e n t i f y likely c a n d i d a t e s f o r use on oceanic f a r m s . Giant kelp, Macrocystis pyrifera w a s selected as a h i g h l y s u i t a b l e s e a w e e d o n several c o u n t s . Macrocystis beds c a n be c o p p i c e d several t i m e s yearly by m e c h a n i c a l h a r v e s t i n g t e c h n i q u e s . T h e species is h i g h l y p r o d u c tive. A h a r v e s t i n g i n d u s t r y utilizing Macrocystis has been a c t i v e in s o u t h e r n California for a l m o s t 7 0 years. W e t h u s have available a w e a l t h of i n f o r m a t i o n c o n c e r n i n g h a r v e s t i n g a n d t h e o p e r a t i o n s i n v o l v e d . Extensive research has p r o d u c e d t e c h n i q u e s for t r a n s p l a t i n g , p r e d a t o r a n d c o m p e t i t o r c o n t r o l , c u l t u r i n g , a n d o t h e r m a n a g e m e n t tools w h i c h are presently utilized in s o u t h e r n California (14, 1_5). For all these reasons, Macrocystis is b e i n g used as t h e test o r g a n i s m in t h e c u r r e n t studies of oceanic f a r m i n g . Other s e a w e e d s m a y prove t o be q u a l l y suitable if t h e scope of t h e research is b r o a d e n e d at s o m e f u t u r e date. T h e first m a j o r a c t i v i t y u n d e r t a k e n by t h e M a r i n e Farm Project i n v o l v e d studies of Macrocystis t r a n s p l a n t s m o o r e d o n artificial s t r u c t u r e s in o c e a n i c e n v i r o n m e n t s . T h e largest of t h r e e s u c h e x p e r i m e n t s c o n s i s t e d of a t h r e e hectare s t r u c t u r e d e s i g n e d a n d installed by t h e Naval Undersea Center off San C l é m e n t e Island, a b o u t 1 0 0 k m f r o m t h e m a i n l a n d . T h e s t r u c t u r e c o n s i s t e d of a g r i d or n e t w o r k of ropes, d e p l o y e d 15 t o 2 0 m b e n e a t h t h e sea surface by a s y s t e m of cables, b u o y s , a n d a n c h o r s 0 6 ) . Overall w a t e r d e p t h r a n g e d f r o m a b o u t 7 0 t o 150 m. A p p r o x i m a t e l y 130 a d u l t Macrocystis t r a n s p l a n t s w e r e relocated o n t o t h e g r i d d u r i n g s u m m e r a n d fall, 1974. The source of t r a n s p l a n t s w a s a nearby kelp bed at San C l é m e n t e Island w h i c h



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w a s also used as a c o n t r o l f o r o u r m e a s u r e m e n t s . G r o w t h p e r f o r m a n c e s by test plants a n d c o n t r o l s y i e l d e d m e a n e l o n g a t i o n rates of 4.6 vs 7.6 p e r c e n t per d a y respectively, a m o n g j u v e n i l e f r o n d s . N i t r o g e n c o n t e n t of blade per tissues in t h e t r a n s p l a n t s fell t o 0.7 t o 0.8 p e r c e n t of t h e d r y w e i g h t c o m p a r e d t o a range of 0.9 t o 1.4 p e r c e n t d r y w e i g h t a m o n g t h e c o n t r o l s . T h e e x p e r i m e n t a l plants soon d i s p l a y e d u n u s u a l l y dense a c c u m u l a t i o n s o f bryozoan e n c r u s t a t i o n s . Presumably, t h e s p r e a d i n g rate of t h e bryozoan colonies e x c e e d e d e x p a n s i o n rate of t h e u n d e r l y i n g , s l o w l y g r o w i n g blade tissues. These general f i n d i n g s at t h e San C l é m e n t e Island f a r m w e r e c o n f i r m e d b y a d d i t i o n a l e x p e r i m e n t s at t w o o t h e r sites. W e c o n c l u d e d t h a t l o w c o n c e n t r a t i o n s o f dissolved n u t r i e n t s in oceanic surface w a t e r s w e r e a p p a r e n t l y unable t o sustain n o r m a l g r o w t h rates by kelp tissues. W e also n o t e d i m p r o v e m e n t in kelp g r o w t h d u r i n g periods w h e n natural u p w e l l i n g w a s intense a n d t h e n u t r i e n t - r i c h deep w a t e r m o v e d u p into s h a l l o w d e p t h s . W e f u r t h e r d e t e c t e d faster kelp g r o w t h d u r i n g e x p e r i m e n t s w h e r e w a t e r artificially u p w e l l e d f r o m d e p t h s of 3 0 t o 4 5 m w a s i n t r o d u c e d a r o u n d t h e e x p e r i m e n t a l plants ( V U A p p a r e n t l y , o b t a i n i n g h i g h biomass yields f r o m oceanic f a r m s necessitates fertilizing operations. Costs a n d energetic r e q u i r e m e n t s c o n n e c t e d w i t h d i s p e r s i n g c o m m e r c i a l fertilizers o n m a r i n e f a r m s have led analysts t o favor use o f artificially u p w e l l e d d e e p w a t e r as a source of n u t r i e n t s (V7). There has been c o n c e r n , h o w e v e r , t h a t t h e a m o u n t s of freely available metallic ions, s u c h as c o p p e r and zinc in deep w a t e r , m i g h t be s u f f i c i e n t t o i n h i b i t kelp g r o w t h . Likewise, d e e p w a t e r m i g h t n o t c o n t a i n a full c o m p l e m e n t o f required e l e m e n t s or t h e i r c o n c e n t r a t i o n s m i g h t n o t be in proper balance. W e a t t e m p t e d t o resolve these and other q u e s t i o n s t h r o u g h laboratory c u l t u r i n g studies c o m p a r i n g g r o w t h in deep a n d surface w a t e r m e d i a . W e have also a t t e m p t e d t o d e t e r m i n e t h e e l e m e n t a l r e q u i r e m e n t s of Macrocystis b y c u l t u r i n g g a m e t o p h y t e s a n d juveniles s p o r o p h y t e s in a c h e m i c a l l y d e f i n e d artificial s e a w a t e r k n o w n as A q u i l . S U M M A R Y OF LABORATORY FINDINGS Culturing W o r k in S e a w a t e r M e d i a M a n y m i c r o n u t r i e n t s in s e a w a t e r o c c u r at e x t r e m e l y l o w c o n c e n t r a t i o n s . A c c i d e n t a l c o n t a m i n a t i o n of laboratory w a r e can easily alter levels of s o m e critical e l e m e n t s q u i t e p r o f o u n d l y . For t h o s e w h o m i g h t w i s h t o repeat o u r e x p e r i m e n t s , s c r u p u l o u s cleanliness is m a n d a t o r y in all phases of t h e w o r k . Our c u l t u r i n g studies have utilized s e a w a t e r c o l l e c t e d f r o m a d e p t h range of 0 t o 8 7 0 m. M o s t e x p e r i m e n t s , h o w e v e r , w e r e c o n d u c t e d w i t h w a t e r f r o m 3 0 0 m deep, c o l l e c t e d a b o u t 5 k m offshore f r o m o u r laboratory headquarters


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at Corona del M a r , California. T y p i c a l e x p e r i m e n t s i n v o l v e d b a t c h c u l t u r i n g c o n d i t i o n s u s i n g 4 0 - 1 aquaria (18). S m a l l Macrocystis s p o r o p h y t e s (wet w e i g h t s of 0.5 t o a b o u t 15 g) w e r e t h e test o r g a n i s m s . T h e e x p e r i m e n t a l d e s i g n m a d e it unlikely t h a t n i t r o g e n or p h o s p h o r u s w o u l d be l i m i t i n g w h e n u s i n g d e e p w a t e r 2 5 t o 3 0 μ M in nitrate. A n e x p e r i m e n t a l series e m p l o y i n g n o n e n r i c h e d 3 0 0 - m w a t e r as t h e m e d i u m y i e l d e d m e a n s p e c i f i c g r o w t h rates r a n g i n g f r o m a b o u t 8 t o 1 8 p e r c e n t daily w e i g h t increases w i t h i n a 1 3 - m o n t h p e r i o d of t e s t i n g (Figure III). T h e series c o m p r i s e d 4 8 i n d e p e n d e n t e x p e r i m e n t s e a c h e m p l o y i n g f r o m t w o t o nine plants. S o m e of t h e v a r i a b i l i t y in results u n d o u b t e d l y arose f r o m p h y s i o l o g i cal differences a m o n g t h e plants. There w a s e v i d e n c e , h o w e v e r , t h a t c h a n g e s in c o m p o s i t i o n of t h e d e e p w a t e r in part c o n t r i b u t e d t o t h e f l u c t u a t i o n s seen in Figure III. For e x a m p l e , f r o m t i m e t o t i m e w e c o n d u c t e d a parallel c u l t u r i n g series w h e r e t h e 3 0 0 - m w a t e r w a s s u p p l e m e n t e d w i t h m a n g a n e s e t o g i v e 1 m i c r o m o l a r c o n c e n t r a t i o n s of M n in t h e m e d i u m . S i m u l t a n e o u s l y , b a c k g r o u n d M n c o n c e n t r a t i o n s in t h e n o n e n r i c h e d 3 0 0 - m w a t e r w e r e r o u t i n e l y d e t e r m i n e d by A A S . W e f o u n d t h a t s u p p l e m e n t i n g d e e p w a t e r w i t h Mn s t i m u l a t e d kelp g r o w t h d u r i n g periods w h e n b a c k g r o u n d M n fell b e l o w d e t e c t a b l e levels (Table I). Conversely, a d d i t i o n s o f M n c o u l d even be m i l d l y i n h i b i t o r y w h e n t h e A A S analyses revealed presence of t h e e l e m e n t in d e e p water. W e have similarly f o u n d t h a t s u p p l e m e n t i n g 3 0 0 - m w a t e r with F e m a y or m a y n o t s t i m u l a t e kelp g r o w t h . W e have never o b s e r v e d a clearly s t i m u l a t o r y response f r o m e n r i c h i n g d e e p w a t e r w i t h Z n or w i t h Cu . Occasionally, h o w e v e r , m i l d g r o w t h s t i m u l a t i o n a c c o m p a n i e d a d d i t i o n s of c o p p e r , at a p p r o p r i a t e c o n c e n t r a t i o n s , t o offshore surface w a t e r . Iron a n d m a n g a n e s e c o n c e n t r a t i o n s have a l w a y s a p p e a r e d e n t i r e l y a d e q u a t e in surface w a t e r s a l t h o u g h o u r t e s t i n g has been l i m i t e d . + 2

+ 2

+ 3

+ 2

+ 2

M a x i m a l g r o w t h by y o u n g Macrocystis s p o r o p h y t e s w a s o b t a i n e d in a f l o w i n g s y s t e m w h e r e t h e m e d i u m c o n s i s t e d of equal parts of surface a n d of w a t e r f r o m 8 7 0 m d e e p (16). It appears t h a t i n a d e q u a c i e s of d e e p w a t e r w e r e m e t by c o m p o n e n t s of surface w a t e r a n d v i c e versa. C o n s e q u e n t l y , at t h i s t i m e , o u r laboratory w o r k indicates t h a t m i x t u r e s of t h e t w o w a t e r t y p e s s h o u l d p r o v i d e a n e a r - o p t i m a l m e d i u m for fertilizing plants o n o c e a n i c farms. M o s t of o u r studies have been d o n e at l o w light intensities c h a r a c t e r i s t i c of t h e sea floor in kelp beds. Recent w o r k i n d i c a t e d t h a t specific g r o w t h rates increase at h i g h light intensities. Needs for n u t r i e n t s w i l l u n d o u b t e d l y be greater t o m a i n t a i n s u c h h i g h g r o w t h rates, so t h a t p r e v i o u s l y established n u t r i e n t resources m a y require réévaluation in t e r m s of t h e greater needs.


Klass; Biomass as a Nonfossil Fuel Source ACS Symposium Series; American Chemical Society: Washington, DC, 1981. ND ND 3.6 17 4.3 3.6 4.0 1.6 ND

10/31/77 11/15/77 2/6/78 4/24/78 5/23/78 7/6/78 8/4/78 9/19/78 10/17/78 b

Background M n nM/f ND

Date of Sampling 5/5/77

A p p r o x i m a t e end of a severe rainy season.

Temporal relations between background concentration of M n in seawater from 3 0 0 m deep and the effect on kelp g r o w t h w h e n 300-m water w a s enriched w i t h M n at one μ Μ . This effect w a s taken as the difference between the mean specific g r o w t h rate s h o w n by plants in Mn-enriched water minus the mean rate in nonenriched 300-m water. Background M n w a s determined by atomic absorption spectroscopy. ND =• Not detected (i.e. concentration below one nM). Enrichment w i t h M n tended to stimulate g r o w t h (i.e. positive values for the differences between experimental and control g r o w t h rates) w h e n background M n w a s low. Enrichment w i t h M n inhibited g r o w t h w h e n background M n w a s high. Numbers of juvenile sporophytes involved given in parentheses.

-0.1 +4.7

13.3 (6) 15.0 (8)

13.4 (6) 10.3 (6)

10/22/78-10/29/78 11/5/78-11/12/78

-2.7 -0.3 -1.8

7.4 (5) 13.3 (5) 12.0 (5)

10.1 (8) 13.6 (5) 13.8 (5)

5/2/78-5/8/78 7/16/78-7/23/78 7/23/78-7/30/78

Dates of Testing 6/3/77-6/16/77 9/24/77-10/5/77 10/25/77-11/2/77 11/2/77-11/6/77 11/12/77-11/20/77 11/20/77-11/26/77 2/7/78-2/15/78

M e a n Specific Growth Rate Enriched Difference Nonenriched Medium Medium + 5.5 14.5 (3) 9Ό (5) 10.4 (6) 13.0 (3) +2.6 12.3 (6) +4.1 8.2 (5) 9.3 (3) 10.3 (3) -1.0 11.5 (3) -0.7 12.2 (3) 11.4 (3) 14.0 (3) -2.6 10.9 (5) 13.7 (5) -2.8

Table I. EFFECT OF M A N G A N E S E O N KELP G R O W T H *


86

BIOMASS AS A NONFOSSIL

FUEL

SOURCE


Culturing W o r k Using t h e Defined M e d i u m Aquil A n artifical s e a w a t e r n a m e d A q u i l w a s devised b y M o r e l a n d associates f o r c u l t u r i n g m a r i n e o r g a n i s m s (19). Because A q u i l is a c h e m i c a l l y d e f i n e d s e a w a t e r m e d i u m , c h e m i c a l s p e c i a t i o n c a n be c o m p u t e d u s i n g a n e q u i l i b r i u m c o m p u t e r p r o g r a m called REDEQL2 (20). A q u i l c o n t a i n s eleven m a j o r c o m p o n e n t s in f i x e d a m o u n t s . These c o r r e s p o n d t o t h e p r i n c i p a l i n o r g a n i c c o n s t i t u e n t s of seawater. C o n c e n t r a t i o n s of m a c r o n u t r i e n t s , s u c h as n i t r a t e a n d p h o s p h a t e , a n d c e r t a i n t r a c e m e t a l s m a y be varied as desired for a g i v e n A q u i l f o r m u l a t i o n . W e have r e c e n t l y been able t o c u l t u r e spores f r o m Macrocystis through the entire g a m e t o p h y t i c p o r t i o n of t h e life c y c l e , t o e m b r y o n i c s p o r o p h y t e s as large as 3 0 t o 4 0 cells. A f t e r a t w o - w e e k c u l t u r i n g p e r i o d , v o l u m e s of t h e e m b r y o n i c plants w e r e b e t w e e n 2 0 0 t o 1 0 0 0 t i m e s greater t h a n t h e spores f r o m w h i c h t h e y arose. It seems unlikely t h a t s u c h large v o l u m e increases c o u l d have been entirely s u p p o r t e d b y reserves of n u t r i t i v e e l e m e n t s stored in t h e spores. A n a l t e r n a t i v e h y p o t h e s i s seems m o r e a t t r a c t i v e — n a m e l y , t h a t t h e f o r m u l a t i o n used c o n t a i n e d all e l e m e n t s required b y Macrocystis. A s i d e f r o m t h e m a j o r salts, o n l y nine n u t r i e n t e l e m e n t s w e r e a d d e d (Table II). W e w i l l be g r a t i f i e d if f u r t h e r studies c o n f i r m t h i s f i n d i n g because t h e n u m b e r of p o t e n t i a l l y l i m i t i n g c o m p o n e n t s a f f e c t i n g Macrocystis nutrition appears t o be relatively small. Table II. M E D I U M FOR K E L P G R O W T H * Amount Nutrient used Fe

+ 3

Mn Co Cu

+ 2

2

NO3PO4-

a

1

1

3

2

(%) (100)

1

ΜηEDTA

(65) (23)

0.04

MnCI CoEDTA

5

4

Present FeEDTA

10

+ 2

2

Major Species

7 x 10"

40

Mo0 " EDTA"

Free Ion Cone, η M

400

+ 2

Zn+

Γ

Added. n M

11

+

(99)

0.0000

CuEDTA

(99)

250

0.12

ZnEDTA

(100)

100

100 0.00007

CaEDTA FeEDTA

(89)

6.000 15.000 2.000

15.000 0.3

100

100

HPO4MgHP04

2

(6) (51) (47)

Nannomoles of nine inorganic nutrients and of EDTA added to the completely defined artificial seawater Aquil to yield a medium that sustained development by Macrocystis zoospores in petri-dish cultures completely through the gametophyte stage to embryonic sporophytes.


4.

NORTH E T A L .


87


PRESENT FIELD STUDIES Our laboratory w o r k t h u s s u g g e s t s t h a t w e can e x p e c t s t r o n g s t i m u l a t i o n of g r o w t h w h e n d e e p w a t e r is dispersed a m o n g plants o n a f a r m (e.g., c o m p a r e t h e level of average g r o w t h c a l c u l a t e d f o r small s p o r o p h y t e s in natural kelp beds w i t h values a c h i e v e d in 3 0 0 - m w a t e r , Figure 3). It is d i f f i c u l t , h o w e v e r , t o t r a n s l a t e o u r laboratory d a t a i n t o q u a n t i t i v e p r e d i c t i o n s o f yields f r o m a d u l t Macrocystis residing in artificially u p w e l l e d w a t e r . It is also risky t o i n t e r p o l a t e f r o m yield m e a s u r e m e n t s c o n d u c t e d a m o n g kelp beds. Product i v i t y in m o s t , if n o t a l l , of s o u t h e r n California's kelp beds appears t o be l i m i t e d f o r s u b s t a n t i a l p o r t i o n s of each year b y availability of n u t r i e n t s . N u t r i e n t supplies f r o m u p w e l l i n g a n d runoff are q u i t e variable a n d d i f f i c u l t t o define precisely. Nonetheless, reliable information c o n c e r n i n g yields e x p e c t e d f r o m a d u l t plants c o m p l e t e l y free of n u t r i e n t l i m i t a t i o n s is central t o assessing e c o n o m i c feasibility o f t h e m a r i n e f a r m c o n c e p t . T h e M a r i n e Farm Project presently is in t h e early stages of a large-scale field e x p e r i m e n t i n t e n d e d t o p r o v i d e k n o w l e d g e in t h i s critical area (Figure IV). One of our collaborators, Global M a r i n e D e v e l o p m e n t , Inc., revised t h e d e s i g n of a s t r u c t u r e , c o n c e i v e d at t h e Naval Ocean Systems Center, w h i c h w a s d e s i g n e d t o s u p p o r t a b o u t 1 0 0 a d u l t Macrocystis transplants and supply t h e m w i t h a b u n d a n t q u a n t i t i e s of w a t e r p u m p e d u p f r o m d e p t h s of a b o u t 4 5 0 m (Figure V). This "Test F a r m " w a s d e p l o y e d a b o u t 6 k m f r o m shore, near our laboratory h e a d q u a r t e r s , d u r i n g S e p t e m b e r 1 9 7 8 (Figure VI). W a t e r d e p t h at t h e site w a s a b o u t 5 5 0 m. In m i d - D e c e m b e r , a p r o t e c t i v e c u r t a i n w a s installed a r o u n d t h e w e s t e r n border o f t h e f a r m . This c u r t a i n w a s i n t e n d e d t o r e d u c e effects of c u r r e n t s , w h i c h are o f t e n greater t h a n 0.5 kt, o n t h e t r a n s p l a n t s a n d t o increase r e t e n t i o n t i m e of t h e artificially u p w e l l e d deep w a t e r w i t h i n t h e f a r m . T h e c u r t a i n w a s lost t o s t o r m s w i t h i n t h e f o l l o w i n g week. A n initial c r o p of 103 a d u l t Macrocystis f r o m local beds w a s t r a n s p l a n t e d t o t h e s t r u c t u r e d u r i n g N o v e m b e r - D e c e m b e r 1978. Our i n t e n t i o n w a s t o harvest a n d w e i g h u p p e r p o r t i o n s of t h e plants at a p p r o p r i a t e intervals t o d e t e r m i n e yields. W e m e a s u r e d g r o w t h rates a n d n u t r i e n t c o n c e n t r a t i o n s w i t h i n t h e tissues a n d in t h e w a t e r . W e also f o l l o w e d r e p r o d u c t i v e success o n solid substrates of t h e s t r u c t u r e , general health a n d appearance of t h e test plants, a n d t h e d e v e l o p m e n t of an associated c o m m u n i t y , as w e l l as other related p a r a m e t e r s (see Figure IV). T h e e x p e r i m e n t w a s s c h e d u l e d t o last f o r t w o years; h o w e v e r , all t r a n s p l a n t s had been d e s t r o y e d by t h e e n d of t w o m o n t h s , p r i m a r i l y d u e t o lack of p r o t e c t i o n f r o m c u r r e n t .



88

BIOMASS AS A N O N F O S S I L

FUEL

SOURCE

20r-

I— Aug. 1977

1

1

Sept.

Oct.

ι Nov.

ι Otc.

I Jon. 1978

ι

ι Fab.

ι Mar.

ι Apr.

ι May

1

Junt

July

1

Aug.

4 Stpt.

Figure 3. Record snowing variation with time of mean specific growth rates ob tained from groups of juvenile Macrocystis sporophytes cultured in seawater pumped up from depths of 300 m. The batch cultures employed 40 L aquaria with the medium being renewed every other day.



fc

I d e n t i f y necessary inputs Amounts o f inputs needed I d e n t i f y c r i t i c a l species Determine uptake r a t e s Optimize inputs

OPERATIONAL SUPPORT STUDIES

Transplanting Plant maintenance F e r t i l i z i n g (juveniles) Mechanical monitoring Grazer c o n t r o l

OPERATIONAL ACTIVITIES

Growth assessments J u v e n i l e fronds Adult fronds Frond i n i t i a t i o n r a t e s Frond production r a t e s Harvest y i e l d s T i s s u e n u t r i e n t contents Nitrogen Trace metals General h e a l t h & appearance J u v e n i l e recruitment A s s o c i a t e d community

OUTPUT STUDIES

Biomass Juvenile plants A s s o c i a t e d species

OUTPUTS

Figure 4. Relationships between fluxes of energy and materials at the Test Farm and the principal groupings that constitute operation and monitoring of the Farm by staff of the California Institute of Technology

Biological Encrustations Diseases Competitors Grazers Nutrient r e c y c l i n g

Chemical Salinity Oxygen Nutrients Mean concentrations & s p e c i a t i o n Temporal v a r i a t i o n Vertical distributions H o r i z o n t a l d i s t r i b u t i o n (on farm)

Physical Water c l a r i t y Water temperature S t a b i l i t y o f deep water Water movements Entangling o f fronds Abrasion of t i s s u e s

ENVIRONMENTAL STUDIES

/

Sunlight Water Carbon d i o x i d e Mineral nutrients Toxicants or i n h i b i t o r s Substrate i n t e r a c t i o n s Biological interactions

INPUTS


00 VO

s-

1

I 3*

a.

§

I

>

M H

S H Χ


BIOMASS AS A N O N F O S S I L

FUEL

SOURCE

W1 r s//

Figure 5.

\

\

\

The Test Farm structure with 100 adult Macrocystis transplants indicated diagrammatically

A 0.61-m-diameter polyethylene pipe tending down from the Test Farm supplies 30,000 L/min of nutrient-rich water from 450 m deep to fertilize the transplants. The deep water is discharged horizontally from three pipes 120° apart, just below the water line The striped cylindrical object is a buoy 17 m long that contains machinery and instrumentation. The plant holdfasts are at depths of 15-17 m. The radiating arms are about 32 m from tip to tip.



4.

NORTH

ET

AL.


91

Figure 6. Chart of the southern California coastline from Huntington Beach to Monarch Bay, showing locations of the Test Farm and other geographical features described in the text


92


SOURCE


To date, i n v e s t i g a t i o n s c o n c e r n e d w i t h biological o u t p u t s f r o m t h e Test Farm have e n c o m p a s s e d t w o d e f i n e d t i m e periods: A. D e c e m b e r 1 9 7 8 t o J a n u a r y 1 9 7 9 w h e n our a d u l t t r a n s p l a n t s existed at t h e F a r m ; B. M a y t o A u g u s t 1 9 7 9 w h e n dense p o p u l a t i o n s of j u v e n i l e plants a p p e a r e d , p r e s u m a b l y o f f s p r i n g arising f r o m spores liberated by t h e a d u l t t r a n s p l a n t s five m o n t h s previously. T h e m o s t i m p o r t a n t c o n c l u s i o n s a n d results f r o m o u r D e c e m b e r - J a n u a r y monitoring were: 1.

G r o w t h rates J u v e n i l e f r o n d s : A series of seven w e e k l y d e t e r m i n a t i o n s b e t w e e n D e c e m b e r 12 a n d J a n u a r y 2 9 y i e l d e d m e a n s t a n d a r d g r o w t h rates r a n g i n g f r o m 5.4 t o 7.4 p e r c e n t e l o n g a t i o n per day. These are w i t h i n t h e n o r m a l range for natural kelp beds at t h i s t i m e of year b u t t e n d t o lie p r i m a r i l y w i t h l o w e r p o r t i o n of t h e range. Percent of f r o n d s s h o w i n g a b n o r m a l l y s l o w g r o w t h rates a m o n g t a g g e d j u v e n i l e s ranged f r o m 6% t o 4 4 % of t h e t a g g e d recoveries, a relatively h i g h p r o p o r t i o n of a b n o r m a l juveniles. A b n o r m a l l y s l o w g r o w t h in j u v e n i l e f r o n d s o f t e n results f r o m severe d a m a g e t o or loss of t h e p a r e n t a d u l t f r o n d , t h a t nourishes g r o w t h of t h e j u v e n i l e t h r o u g h t r a n s l o c a t i o n of p h o t o s y n t h a t e . A d u l t f r o n d s : D a m a g e a n d m o r t a l i t y a m o n g a d u l t f r o n d s interferred w i t h assessment so t h a a statistically a d e q u a t e e v a l u a t i o n of g r o w t h rate w a s not possible. It w a s e s t a b l i s h e d , h o w e v e r , t h a t s o m e of t h e t a g g e d s p e c i m e n s g e n e r a t e d reasonable rates of p r o d u c t i o n of n e w blades.

2.

Plant M o r t a l i t y A b o u t 2 / 3 of t h e initial c o m p l e m e n t of t r a n s p l a n t s w e r e lost b e t w e e n D e c e m b e r 5 a n d J a n u a r y 5. M o r t a l i t y d u r i n g t h e n e x t 2 0 days d e c l i n e d , as o n l y a b o u t one t h i r d of t h e r e m a i n i n g plants d i s a p p e a r e d . A s h o r t b u t v i o l e n t squall o n J a n u a r y 3 0 d e s t r o y e d t h e last of t h e t r a n s p l a n t s . T a n g l i n g w i t h a n d abrasion on various parts of t h e test f a r m s t r u c t u r e w e r e t h e sole causes of plant m o r t a l i t y .

3.

N i t r o g e n c o n t e n t s of blade tissues Except for t h e final w e e k of J a n u a r y ( w h e n all of t h e r e m a i n i n g plants h a d suffered s i g n i f i c a n t d a m a g e ) , Ν c o n t e n t s r e m a i n e d a b o v e o n e p e r c e n t of t h e d r y w e i g h t . In our experience, t h i s represents a h e a l t h y n u t r i t i o n a l c o n d i t i o n . Of t h e 8 2 blade samples t a k e n , 7 1 % w e r e a b o u t 1.5% in Ν c o n t e n t . T h e h i g h e s t Ν c o n t e n t s w e r e a r o u n d 2.5% a n d c a m e f r o m c a n o p y blades d u r i n g t h e period w h e n t h e c u r t a i n w a s m o s t effective in r e t a i n i n g t h e u p w e l l e d w a t e r w i t h i n t h e f a r m . W e c o n c l u d e d t h a t , unlike our previous e x p e r i m e n t a l oceanic f a r m s , t h e t r a n s p l a n t s on t h i s test f a r m d i d not suffer f r o m i n a d e q u a t e n u t r i t i o n .


4.

NORTH E T AL.


93

D u r i n g January 1 9 7 9 , w e observed s o m e small j u v e n i l e Macrocystis a t t a c h e d t o several o f t h e p l a n t i n g buoys. Only a m o n t h had elapsed since t h e t r a n s p l a n t s had been i n t r o d u c e d . W e therefore p r e s u m e d t h a t these j u v e n i l e s reached t h e test f a r m as established m i c r o s c o p i c - s i z e d plants a n d d i d n o t arise f r o m spores liberated at t h e test f a r m . Usually at least t h r e e m o n t h s are needed f o r d e v e l o p m e n t of barely visible j u v e n i l e s f r o m settled kelp spores,


and t h e t i m e m a y be longer if light or n u t r i e n t s are n o t o p t i m a l . In late A p r i l 1 9 7 9 , w e observed small plants d e v e l o p i n g near t h e ends o f t h e test f a r m dispersion hoses. By M a y , large n u m b e r s of juveniles w e r e a p p e a r i n g o n m o s t o f t h e solid surfaces of t h e test f a r m s t r u c t u r e d o w n t o d e p t h s as great as 3 0 m. C o n c e n t r a t i o n s w e r e sparse, h o w e v e r , b e l o w t h e level o f t h e t r a n s p l a n t i n g s u b s t r a t e (20 m). D e v e l o p m e n t b y most of these plants w a s p r o b a b l y s t i m u l a t e d n o t b y t h e artificially u p w e l l e d deep w a t e r b u t b y natural u p w e l l i n g w h i c h usually is m a x i m a l d u r i n g late s p r i n g . T h e j u v e n i l e recruits w e r e s t u d i e d intensively t o g a t h e r e c o l o g i c a l i n f o r m a t i o n t h a t m i g h t be useful f o r e n c o u r a g i n g a n d assisting kelp r e p r o d u c t i o n o n t h i s a n d o n o t h e r oceanic farms. Several n o t e w o r t h y results e m e r g e d . 1.

Total plant p o p u l a t i o n o n t h e substrate a r m s , cables, a n d p l a n t i n g b u o y s w a s e s t i m a t e d t o be 3 6 . 0 0 0 individuals.

2.

T e m p o r a l c h a n g e s in n i t r o g e n c o n t e n t s of kelp blades paralleled c h a n g e s in a m b i e n t nitrate c o n c e n t r a t i o n s (nitrate is a g o o d measure of natural u p w e l l i n g in this instance) a n d correlated w i t h c h a n g e s in rates of plant e l o n g a t i o n .

3.

Greatest plant m o r t a l i t y o c c u r r e d o n t h e s m o o t h p l a s t i c - c o a t e d cables. Plants w e r e p r o b a b l y easily d i s l o d g e d b y w a t e r m o v e m e n t s f r o m t h i s t y p e o f substrate. High m o r t a l i t y rates also o c c u r r e d a m o n g plants on t h e u p w e l l i n g hoses w h e r e barnacle e n c r u s t a t i o n s proliferated and c r e a t e d e x t r e m e l y abrasive surfaces. I n t e r m e d i a t e degrees o f m o r t a l i t y o c c u r r e d on t h e p l a n t i n g b u o y s a n d s u b s t r a t e arms. L o w e s t m o r t a l i t y appeared a m o n g plants a t t a c h e d t o t h e m o d e r a t e l y r o u g h surfaces p r o v i d e d b y polyester ropes.

4.

Tissue n i t r o g e n c o n c e n t r a t i o n a n d g r o w t h w a s e n h a n c e d s l i g h t l y b y " s p r a y i n g " a g r o u p of j u v e n i l e s o n a s u b s t r a t e a r m , t w i c e w e e k l y w i t h 1 M a m m o n i u m sulfate. Even greater e n h a n c e m e n t o c c u r r e d a m o n g plants close t o bags of O s m o c o t e pellets affixed t o t h e side of a substrate a r m . T h e pellets s l o w l y released n i t r o g e n a n d p h o s p h o r u s into t h e surrounding water.


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In s u m m a r y , perhaps t h e m o s t revealing result t h u s far f r o m t h e test f a r m e x p e r i m e n t w a s our failure t o observe increased g r o w t h rates a m o n g t h e j u v e n i l e f r o n d s d u r i n g t h e period w h e n t h e c u r t a i n w a s r e t a i n i n g t h e n u t r i e n t rich d e e p w a t e r a n d h i n d e r i n g effects by c u r r e n t s . This very p r e l i m i n a r y f i n d i n g s u g g e s t s t h a t g r o w t h of j u v e n i l e f r o n d s m a y be l i m i t e d b y t h e rate at w h i c h p h o t o s y n t h a t e c a n be t r a n s l o c a t e d d o w n w a r d f r o m t h e c a n o p y a n d not f r o m l i m i t e d availability of n u t r i e n t s (in t h i s p a r t i c u l a r case). W h i l e w e need m o r e e x p e r i m e n t a t i o n t o establish t h i s h y p o t h e s i s , t h e p o s s i b i l i t y has i m p o r t a n t i m p l i c a t i o n s for o p t i m i z i n g b i o m a s s p r o d u c t i o n . If t r a n s l o c a t i o n rate is i m p o r t a n t as a l i m i t i n g f a c t o r in j u v e n i l e f r o n d g r o w t h , t h e best s t r a t e g y w o u l d involve t r y i n g t o a c h i e v e a c o n d i t i o n w h e r e availability of l i g h t b e c o m e s t h e p r i n c i p a l l i m i t i n g factor. P r e s u m a b l y t h i s c o u l d be d o n e by increasing f r o n d d e n s i t y o n t h e f a r m (i.e. p l a c i n g t h e p l a n t s m o r e closely together). For t h e f u t u r e , o u r c o l l a b o r a t o r s at General Electric w i l l be i n s t a l l i n g a m o r e d u r a b l e p r o t e c t i v e c u r t a i n at t h e p e r i p h e r y of t h e test f a r m in late 1 9 7 9 . W e w i l l t h e n be able t o r e s u m e o u r studies m o n i t o r i n g health a n d m e a s u r i n g p r o d u c t i v i t y of a d u l t kelp plants b e i n g held in t h e artificially u p w e l l e d d e e p water. B I O M A S S STUDIES A T W H O I Studies by Ryther a n d c o - w o r k e r s of W H O I have been l o c a t e d for a b o u t three years at t h e Harbor Branch F o u n d a t i o n , Inc., f a c i l i t y in central Florida. The site has t h e a d v a n t a g e of a s u b t r o p i c a l l o c a t i o n w i t h access t o b o t h f r e s h w a t e r a n d m a r i n e e n v i r o n m e n t s . Earlier w o r k o n Neoagardhiella, Gracilaria. Hypnea, a n d o t h e r s e a w e e d s h a d been c o n d u c t e d d i r e c t l y at W H O I in M a s s a c h u s e t t s (20). Initial phases at t h e Florida site i n c l u d e d general surveys t o screen t h e m o s t p r o m i s i n g c a n d i d a t e species in t e r m s of ease of c u l t u r i n g and p e r f o r m a n c e in biomass p r o d u c t i o n . Of t h e 4 2 Floridanian seaweeds e x a m i n e d , Gracilaria tikvahiae s h o w e d greatest p r o m i s e (22). Effects on yields of f l o w rates, n u t r i e n t c o n c e n t r a t i o n s , w a t e r t e m p e r a t u r e , solar r a d i a t i o n , salinity, a n d plant d e n s i t y w e r e e x a m i n e d for Gracilaria a n d others ( 2 1 . 23). Yields by Gracilaria w e r e d e t e r m i n e d on a w e e k l y basis t h r o u g h o u t t h e year for plants held in f l o w i n g s y s t e m s e n r i c h e d w i t h a m m o n i u m or n i t r a t e (10 t o 1 0 0 μ M) a n d w i t h p h o s p h a t e (1 t o 10 μ M) a n d essential t r a c e metals. Cultures w e r e e x p o s e d t o a m b i e n t c o n d i t i o n s of full s u n l i g h t a n d t e m perature. T h e m e a n a n n u a l yield for Gracilaria w a s 34.8 d r y g / m - d a y (25.4 d r y ash-free t o n s / a c - y r ) . Progress w a s m a d e in e p i p h y t e c o n t r o l by s h a d i n g infested plants, by w i t h h o l d i n g n u t r i e n t s for 5 t o 10 days, or by use of an 2


4.

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ET AL.

95


e p i p h y t e - g r a z i n g snail, Costoanarchis avara. Preliminary a t t e m p t s t o raise s e a w e e d species, i n c l u d i n g Gracilaria, in a s e m i - o c e a n i c m e d i u m (a p o w e r plant's d i s c h a r g e candal) w e r e n o t successful. A p p a r e n t l y n u t r i e n t c o n c e n t r a t i o n s w e r e i n a d e q u a t e . Of f o u r f r e s h w a t e r a n g i o s p e r m s e v a l u a t e d , w a t e r h y a c i n t h , Eichhornia crassipes. w a s m u c h superior t o d u c k w e e d a n d Hydrilla a n d w e l l a b o v e p e n n y w o r t ( p e n n y w o r t , h o w e v e r , m i g h t be useful in c l i m a t e s colder t h a n t o l e r a t e d b y h y a c i n t h a n d t h e others). M e a n a n n u a l p r o d u c t i v i t y b y h y a c i n t h w a s 24.2 d r y g / m - d a y (range 5.3 t o 34.9 g / m - d a y ) or 2 8 d r y ash-free t o n s / a c - y r ) . Yields f r o m natural stands o f h y a c i n t h s a n d o t h e r f r e s h - w a t e r m a c r o p h y t e s gave values less t h a n 1/3 of those o b t a i n e d f r o m laboratory studies. O p t i m a l c u l t u r i n g d e n s i t y for h y a c i n t h s in t e r m s of biomass p r o d u c t i o n w a s in t h e range 10 t o 2 0 w e t k g / m w h i l e t h e range w a s l o w e r for Gracilaria, ca. 1 t o 4 k g / m . H y a c i n t h p r o d u c t i v i t y e s t i m a t e d b y n u t r i e n t uptake m e a s u r e m e n t s y i e l d e d m e a n values a b o u t 12 percent b e l o w similar d e t e r m i n a t i o n s b y t h e m e t h o d of w e i g h t gains. P r o d u c t i v i t y on a large p l a n t a t i o n c o u l d p r o b a b l y be e s t i m a t e d m o r e easily b y n u t r i e n t u p t a k e m e a s u r e m e n t s t h a n b y w e i g h t c h a n g e s . T h e presence of h y a c i n t h s increased e v a p o r a t i v e and t r a n s p i r a t i o n a l w a t e r losses f r o m t h e c u l t u r i n g c o n t a i n e r b y a b o u t 1.7 t i m e s a b o v e t h a t d u e t o s i m p l e e v a p o r a t i o n f r o m o p e n w a t e r . Studies e v a l u a t e d s u i t a b i l i t y as fertilizer f o r h y a c i n t h c u l t u r e o f residues f r o m digesters o p e r a t e d o n h y a c i n t h biomass. Residues s u p p o r t e d 5 4 p e r c e n t higher g r o w t h c o m p a r e d t o t h e c h e m i c a l l y - e n r i c h e d s t a n d a r d m e d i u m used in r o u t i n e c u l t u r i n g . Efficiency o f utilization of n i t r o g e n in t h e s y s t e m h y a c i n t h - d i g e s t e r r e s i d u e - h y a c i n t h w a s 3 1 percent. T h e digester p r o d u c e d 0 . 4 1 of gas (60 p e r c e n t m e t h a n e ) per g r a m volatile solids f r o m h y a c i n t h s . Similar studies w e r e progressing u s i n g Gracilaria as t h e e x p e r i m e n t a l plant. Dr. Ryther's g r o u p e x p e c t s t o e x p a n d t h e operational scales for c u l t u r i n g Gracilaria a n d Eichhornia, u l t i m a t e l y e x p e r i m e n t i n g w i t h p o n d s of o n e q u a r t e r acre size.


2

2

2

2

Dr. Joel G o l d m a n is c u r r e n t l y i n v e s t i g a t i n g utilization of inorganic c a r b o n b y algae t o p r o v i d e f a c t u a l bases f o r e n s u r i n g t h a t c u l t u r e s never b e c o m e l i m i t e d b y this e l e m e n t a n d f o r e c o n o m i c analysis. Studies t h u s far have u t lized m i c r o a l g a e b u t t h e scope w i l l e v e n t u a l l y be e x p a n d e d t o i n c l u d e m a c r o p h y t e s . Studies i n c l u d e t h e role of c a r b o n d i o x i d e a n d of b i c a r b o n a t e as c a r b o n sources, effects of p H a n d o f m i x i n g , a n d d e f i n i n g c u l t u r i n g c o n d i t i o n s required for t h e m o s t e c o n o m i c a n d efficient means f o r s u p p l y i n g a d e q u a t e c a r b o n t o mass c u l t u r e s of algae (24). Tolerance t o a b n o r m a l l y l o w or h i g h p H values varied a m o n g algal species. Utilization of b i c a r b o n a t e as a c a r b o n source reduces t h e b u f f e r i n g c a p a c i t y of natural w a t e r s . The pH t e n d s t o rise because h y d r o g e n ions are assimilated a n d h y d r o x y l ions are liberated as b i c a r b o n a t e is utilized. G o l d m a n c o n t r o l l e d p H w i t h o r g a n i c buffers in o n e e x p e r i m e n t a l series w i t h Phaeodactylum tricornutum. This marine d i a t o m



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utilized b i c a r b o n a t e at efficiencies of 9 0 t o 100 p e r c e n t across c o n c e n t r a t i o n s r a n g i n g up t o m o r e t h a n f o u r f o l d above natural levels. G o l d m a n c o n c l u d e d t h a t b i c a r b o n a t e s h o u l d easily be able t o fulfill c a r b o n r e q u i r e m e n t s of p r o d u c t i v e species s u c h as Phaeodactylum, provided that m i x i n g a n d p H c o n t r o l are adequate. Bicarbonate w a s as g o o d a c a r b o n source as gaseous c a r b o n d i o x i d e for t h e f r e s h w a t e r C h l o r o p h y t e Chlorella vulgaris, b u t not for Scenedesmus obliquus. under batch conditions. G o l d m a n c o n c l u d e d t h a t t h e rate of s u p p l y of gaseous c a r b o n d i o x i d e c o n t r o l l e d its availability t o t h e plants, rather t h a n t h e c o n c e n t r a t i o n of c a r b o n d i o x i d e in t h e gas m i x t u r e b u b b l e d t h r o u g h t h e m e d i u m . ACKNOWLEDGEMENTS C u r r e n t research s u p p o r t f r o m t h e U.S. D e p a r t m e n t of Energy u n d e r Contract E(04-3)-1275 a n d f r o m t h e Office of Sea Grants u n d e r Grant No. 0 4 - 5 - 1 5 8 - 1 3 is g r a t e f u l l y a c k n o w l e d g e d , as w e l l as past s u p p o r t f r o m t h e U.S. N a v y a n d t h e National Science F o u n d a t i o n . A d v i c e f r o m Drs. M i c h a e l Barcelona, George J a c k s o n , J a m e s M o r g a n , a n d Clair Patterson, a n d f r o m M i c h a e l B u r n e t t w a s invaluable. Our t h a n k s are also d u e t o Drs. J o h n H. Ryther a n d Joel C. G o l d m a n for h e l p f u l discussions a n d for s u p p l y i n g us w i t h t h e i r m o s t recent i n f o r m a t i o n c o n c e r n i n g t h i e r studies. The a u t h o r s are especially g r a t e f u l t o Sylvia Garcia for t h e A A S d e t e r m i n a t i o n s . T h a n k s are d u e t o t h e Kerckhoff M a r i n e L a b o r a t o r y staff for assistance in all aspects of t h e w o r k : Peter A l l i s o n . Brian A n d e r s o n , Barbara B a r t h , Randall B e r t h o l d , Elliott Crooke, Henry Fastenau. Laurence Jones, V i c t o r i a Kromer, V i r g i n i a M a r t i n i , Frank Sager. T h o m a s S t e p h a n , a n d M a r y A n n W h e e l e r . In part, t h i s w o r k is a result of research s p o n s o r e d by N O A A Office of Sea Grants, D e p a r t m e n t of Commerce.


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REFERENCES 1.

Gerard, V. A. Ph.D. Thesis, University of California, Santa Cruz, Calif., 1976.

2.

Lobban, C. S. Phycologia 1978 17, 196-212.

3.

Rosenthal, R. J.; Clarke, W. D.; Dayton, P. K. Fish. Bull. 1974 72, 670-84.

4.

Neushul, M. In "Biology of Giant Kelp Beds (Macrocystis) in California"; W. J. North, Ed.; J. Cramer, : Lehre, Germany, 1971; pp 241-54.

5.

Sargent, M. C.; Lantrip, L. W. Am. J. Bot. 1952 39, 99-107.

6.

Clendenning, Κ. Α.; Sargent, M. C. In "Biology of Giant Kelp Beds (Macrocystis) in California"; W. J. North, Ed.; J. Cramer,: Lehre, Germany, 1971; pp 169-90.

7.

Lobban, C. S. Ph.D. Thesis, Simon Fraser University, Burnaby, Canada, 1976.

8.

Parker, B. C. In "Biology of Giant Kelp Beds (Macrocystis) in California"; W. J. North, Ed.,; J. Cramer: Lehre, Germany, 1971; pp 190-95.

9.

North, W. J. "Proceedings", Symposium on Chilean Algae, Universidad Catolica, Santiago, Chile, Nov. 1978.

10. North, W. J. In "Biology of Giant Kelp Beds (Macrocystis) in California"; W. J. North, Ed.; J. Cramer: Lehre, Germany, 1971; pp 1-97. 11.

North, W. J. "Proceedings", Fuels from Biomass Symposium, University of Illinois, Urbana-Champaign, 1977; pp 99-114.

12.

McPeak, R. H.; Fastenau, H.; Bishop, D. Pasadena, Calif., 1972-73, California Institute of Technology, Kelp Habitat Improvement Project, Annual Report 91125; pp 57-73.

13.

Jackson, G. Α.; North, W. J., China Lake, Calif., 1973, Final Report, Contract No. N60530-73-MV176. U.S. Naval Weapons Center.

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North, W. J., J. Fish. Res. Board Can. 1976 33, 1015-23.


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Wilson, K. C.; Haaker, P. L.; Hanan, D. A. "The Marine Plant Biomass of the Pacific Northwest Coast"; R. W. Krauss, Ed.; Oregon State University Press: Corvallis, 1977; pp 183-202.


16. North, W. J. "Proceedings of the Symposium on Biological Conversion of Solar Energy", University of Miami, 1977; Academic Press: New York, 1977; pp 347-61. 17. Ashare, E.; Augenstein, D. C.; Sharon, A. C.; Wentworth, R. L.; Wilson, E. H.; Wise, D. L. Cambridge, Mass., 1978, DOE Report 1738R. 18.

North, W. J. "Symposium Papers", Clean Fuels from Biomass and Wastes; Institute of Gas Technology: Chicago, Ill., 1977; pp 128-40.

19. Morel, F. M. M.; Rueter, J. G.; Anderson, D. M.; Guillard, R.R.L. J. Phycol. 1979, 15, 135-41. 20.

McDuff, R. E.; Morel, F.M.M. Description and use of the chemical equilibrium program REDEQL2. Tech. Rpt. EQ-73-02, 1975, p 82.

21.

Ryther, J. H.; Lapoints, B. E.; Stenberg, R.W.; Williams, L. D. "Proceedings" Fuels from Biomass Symposium; University of Illinois Press: Urbana, Ill., 1977; pp 83-98.

22. Ryther, J. H.; Williams, L. D.; Hanisak, M. D.; Stenberg, R. W.; DeBusk, T. A. "Proceedings," Third Annual Biomass Energy Systems Conference; SERI: Golden, Colo., in press. 23. Ryther, J. H.; Williams, L. D.; Hanisak, M. D.; Stenberg, R. W.; DeBusk, T. A. "Proceedings," Second Annual Symposium on Fuels from Biomass; Rensselaer Polytechnic Institute: Troy, N.Y. 1978; pp 947-89. 24.

Goldman, J. C. Proceedings," Third Annual Biomass Energy Systems Conference; SERI: Golden, Colo., in press.

RECEIVED M A Y 19,

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Biomass as a Nonfossil Fuel Source - American Chemical Society

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