Survey of oceanographic and meteorological parameters of importance to the site selection of an Ocean Food and Energy Farm (OFEF) in the eastern Pacific : final report, July 1975-September 1976 : prepared for U.S. Energy Research & Development Administration online

port 121



SURVEY OF OCEANOGRAPHIC AND

METEOROLOGICAL PARAMETERS OF

IMPORTANCE TO THE SITE SELECTION

OF AN OCEAN FOOD AND ENERGY

FARM (OFEF) IN THE EASTERN PACIFIC

PF Seligman
15 August 1977

Final Report: July 1975— September 1976

Prepared For
U.S. Energy Research & Development Administration



Approved for public release;
distribution unlimited.






NAVAL OCEAN SYSTEMS CENTER
SAN DIEGO, CALIFORNIA 92152




NAVAL OCEAN SYSTEMS CENTER, SAN DIEGO, CA. 92152



AN ACTIVITY OF THE
RR GAVAZZI, CAPT, USN



NAVAL



Commander



MATERIAL COMMAND
HOWARD L BLOOD, PhD

Technical Director



ADMINISTRATIVE INFORMATION

The Ocean Food and Energy Farm (OFEF) Project was managed by the Naval Ocean
Systems Center. The project is funded jointly by the U.S. Energy Research and Develop-
ment Administration (ERDA) and the American Gas Association (AG A). This is the final
report of Subtask 5 of the ERDA sponsored work for the year ending June 30. 1 976 and is
funded under an Interagency Agreement No. E(49-26)-1027 from ERDA, Division of Solar
Energy to the U.S. Naval Ocean Systems Center.



Released by
S. YAMAMOTO, Head
Chemistry and Environmental
Sciences Group



Under authority of
B. A. POWELL, Head
Undersea Sciences Department



ACKNOWLEDGEMENTS

The assistance from and continuing critical review of this report by Dr. Howard
Wilcox, OFEF Program Manager, is gratefully acknowledged. Many valuable suggestions
were given to me by Dr. Wheeler North of the Cahfomia Institute of Technology, and
Dr. Alberto Zirino and Mr. Doug Murphy of the Naval Ocean Systems Center. The continu-
ing support of Dr. Sachio Yamamoto is appreciated. Assistance in the NODC computer
survey was given by Mr. Joseph Colborn.



UNCLASSIFIED



SECURITY CLASSIFICATION OF THIS PAGE (When HatB Enlerfd)



REPORT DOCUMENTATION PAGE



REPORT NUMBER

TR-121



, GOVT ACCESSION NO



3. RECIPIENT'S CATALOG NUMBEF



SURVEY OF OCEANOGRAPHIC AND METEOROLOGI-
CAL PARAMETERS OF IMPORTANCE TO THE SITE
SELECTION OF AN OCEAN FOOD AND ENERGY
FARM (OFEF) IN THE EASTERN PACIFIC



TYPE OF REPORT A PERIOD COVERED

Final Report: ERDA
Subtask 5 - OFEF Proje ct



6 PERFORMING ORG. REPORT NL MBER



7. AUTHORfs.



8. CONTRACT OR GRANT NUMBERfsJ



Peter F. Seligman



9. PERFORMING ORGANIZATION NAME AND ADDRESS



Naval Ocean Systems Center
San Diego, CA 92152



10. PROGRAM ELEMENT. PROJECT. TASK
AREA a WORK UNIT NUMBERS

ERDA Interagency Agreement
No.E(49-26)-1027toNUC



CONTROLLING OFFICE I



MD ADDRESS



Energy Research and Develop. Admin.
Solar Energy Division



12. REPORT DATE

August 1977



^BER OF PAGES

267



14. MONITORING AGENCY NAME « ADDRESSfi/ di//eri



Confr.iJ/inf} OtI



15. SECURITY CLASS, (o

Unclassified



DISTRIBUTION STATEMENT fu( Ihi s Repori



Approved for public release; distribution unlimited.



7. DISTRIBUTION STATEMENT (ol Ihe «6s



Block 20. il diflerent from Report)



SUPPLEMENTARY NOTES



Oceanography
Meteorology
Eastern Pacific



Ocean Farms

Kelp

Macrocystis pyrifera



19. KEY WORDS (Conli



20. ABSTRACT (Conlinu



,ly by block number)



Oceanographic and meteorological parameters necessary for selection of productive
Ocean Food and Energy Farm (OFEF) sites are presented and compared for the eastern
Pacific Ocean. Optimum values for biological, chemical, physical, and engineering requirements
are estimated for both farm structures and the giant kelp Macrocystis pyrifera , the proposed
OFEF crop plant. From these data, requirements, and limitations, preliminary site selection

criteria are estabhshed.

(over)



DD 1 jAN^a 1473 EDITION OF 1 NOV 65 IS OBSOL ETE



UNCLASSIFIED



SECURITY CLASSIFICATION OF THIS PAGE (HTien Dele Entered)



MBL/WHOI



D D3D1 ODMEm? S



UNCLASSIFIED



CLASSIFICA



20. (Continued)

Selection candidate Phase 1 OFEF and future farm sites are given after a
thorough review of pertinent data and literature. It is determined that within the area
studied, the southern California offshore region from approximately 32°30'N to 34°30'N
is best suited for siting prehininary Ocean Farms. Detailed maps and tables of currents,
ocean temperatures, winds, nutrient concentrations and other parameters are presented.



UNCLASSIFIED



SUMMARY
OBJECTIVES

The principal objectives of this site selection project are to:

• establish preliminary site selection for an ocean food and energy farm (OFEF) based
on the requirements and Umitations of OFEF as delineated by the principal
investigators;

• compile a digest of oceanographic and meteorological data useful to the selection of
the Phase 1 and future fami sites; and

• select candidate Phase 1 sites after a thorough review of pertinent data and literature,
and report these sites in order of increasing importance.

RESULTS

Site selection criteria and requirements are developed and are listed. Pertinent
oceanographic and meteorological data are given in tables, figures and appendices. By com-
paring these criteria to the available environmental data, the southern California offshore
region from 32°30'N to 34°30'N was chosen as the most suitable preliminary site for OFEF.
This area has been selected as the optimal location for Phase 1 , and probably for Phase 2
and early 3 as well, for the following reasons.

1. The sites chosen are within the U.S. economic zone (increased to 200 miles in
March 1977), thereby avoiding possible international conflict.

2. The region has the most mild and least severe extreme weather conditions of any
offshore area within the economic zone of the continental United States or Hawaii. It has a
very low occurrence of high velocity winds and high waves. This is because the region is north of
the tropical cyclone zone and is located on the southern extreme of the extra-tropical
cyclone region.

3. In this nearshore area, nutrients of adequate concentrations are relatively near
the surface (15-25 /ig-at/liter NO3 at 100 meters).

4. Research and support facilities are available close to the proposed sites.

5. The region is within the natural habitat zone of Macrocystis pyrifera . Tempera-
ture and light regions are excellent for Macrocystis growth.

6. Current speeds are mostly within the ranges specified for optimal OFEF opera-
tions and kelp growth characteristics.

RECOMMENDATIONS

It is recommended that: (i) siting of Phase 1 and probably future ocean farms be
within the southern California offshore region; (ii) further research on M. Pyrifera be
performed to define nutrient and temperature requirements and possible synergistic effects
for better definition of potential growing sites; (iii) other worldwide geographic locales be
investigated for possible future siting of OFEF's; and (iv) that thorough current surveys be
conducted at final sites prior to placement of farm. This is necessary for final engineering
requirements and farm configuration planning.



CONTENTS

Page

INTRODUCTION 5

OFEF SITE SELECTION CRITERIA 7

Biological Requirements/Limitations V

Nutrients 7

Temperature 9

Currents 10

Engineering Limitations/Requirements 1 1

Economic Requirements ' 1-

Geopolitical Considerations 1-

OCEANOGRAPHIC AND METEOROLOGICAL SURVEY 1 3

Oceanography 13

Currents 13

Temperature 15

Nutrients 16

Meteorology 20

Tropical and Extratropical Cyclones 21

Winds 22

Wind-Generated Ocean Waves 24

Summary of Meteorological Data 26

Extreme Meteorological Data 29

PRELIMINARY OFEF SITE SELECTION 83

Biological Criteria 83

Temperature 83

Nutrients 83

Currents 85

Engineering Criteria 85

Currents 85

Storms/Wind 86

Waves 86

Economic and Geopolitical Considerations 87



CONTENTS (Continued)



Page



PHASE 1 SITE SELECTION 88

Southern California OFEF Site Selection 88

Southern California Offshore Characteristics 88

Prioritized Phase 1 OFEF Site Selection 91

RECOMMENDATIONS FOR FUTURE OFEF SITING 1 16

APPENDIX A. SEASONAL NITRATE PROFILES 118

APPENDIX B. SEASONAL TEMPERATURE PROFILES 142

APPENDIX C. STATISTICAL SUMMARY OF PHYSICAL OCEANOGRAPHIC

DATA 224

APPENDIX D. METEOROLOGICAL DATA 245

APPENDIX E. DISCUSSION OF STORM-GENERATED CURRENTS 257

REFERENCES 262



INTRODUCTION

The Ocean Food and Energy Farm (OFEF) concept envisions large areas of open
ocean under cultivation utilizing solar energy input and the photosynthetic process to
produce high yields of marine algae. The proposed crop plant, the giant brown kelp
Macrocystis pyrifera, is expected to yield in excess of 270 wet metric tons (36 dry metric
tons) of harvested organic material per acre per year (Refs. 1 and 2). This material would
be harvested and processed to produce methane gas, food and feed products, fertilizer,
ethanol, and other organic products, many of which are currently produced from nonrenew-
able petroleum sources (Ref. 3). In addition, a mariculture subsystem would produce higli-
value finfish and shellfish products for human consumption.

The economic success of any aquaculture system is dependent on the selection of an
appropriate site. Factors which must be considered in selecting potential sites include
various physical, chemical, biological, economic, and geopolitical parameters.

Proper selection of a farm site requires that the needs and hmitations of the total
farm system be considered. Particularly important are the biological requirements of the
kelp Macrocystis pyrifera and the practical engineering and economic factors which affect
design of the farm substrate and artificial upwelling systems.

Biological and chemical parameters of importance to site selection include the
availability and concentration of nutrients in both the near-surface mixed layer (directly
available to crop) and at intermediate depths (100 to 300 meters of depth and available to
the crop after artificial upwelling). Nutrient concentration and availability in combination
with light intensity and temperature are among the principal factors which will determine
the rate of OFEF primary productivity and therefore, economic return. Nutrient concentra-
tions are highly variable in both location and season with the principal determining factors
being the amount of wind-caused mixing, natural upwelling, and biological utilization.

The cost of the substrate system will constitute a large part of the total cost of the
OFEF. The substrate therefore "represents a major investment in an ocean structure which
may be vulnerable to damage during periods of storm and adverse weather conditions" (Ref.
2). Selection of a farm site which minimizes the chance for environmental damage is
consequently of great importance.

The location and intensity of prevailing currents are also important; areas of high-
speed currents may have to be avoided whereas weaker currents can act to remove waste
materials and replenish nutrient supplies.

Other aspects important to the farm location include the amount of incident solar
radiation and degree of light penetration (both vary geographically), the ocean temperature
in relation to M. pyrifera tolerance, and the location and concentration of potential sources
of pollution.



Economic and geopolitical considerations are briefly addressed. The location of
future support and processing facilities in relation to the farm site are important economic
factors. Previously claimed or disputed territorial waters will be areas of high risk until
international agreements are made. Location of traditional sea lanes must be considered.

The general region of the eastern Pacific was chosen for study because of the prox-
imity of support facilities, the positive geopolitical environment, and the need to limit the
area of preliminary consideration to a manageable size.

This report discusses the site selection for one or more Phase 1 prototype farms.
The summary of available environmental data presented, however, are also apphcable to the
selection of future Phase 2 and 3 locations. Site selection is based on criteria as developed
by the principal investigators for the OFEF Project and include Dr. W. North of the Cali-
fornia Institute of Technology and Dr. H. Wilcox and Mr. D. Murphy of the Naval Ocean
Systems Center.



OFEF SITE SELECTION CRITERIA

BIOLOGICAL REQUIREMENTS/LIMITATIONS

Site selection criteria dealing with the biological requirements and limitations are
summarized in Table 1 .

Nutrients

Surface waters of the open ocean in temperate and tropical areas beyond coastal
and upwelling influences are generally nutrient-limited to the degree that the naturally
available nutrients will sustain only low levels of productivity. It has been demonstrated
that nitrogen is the principal controlling nutrient in the eastern tropical Pacific (Refs. 4 and
5) and is the primary nutrient limiting growth of phytoplankton off southern California
(Ref. 6).

Studies of marine macroalgae productivity as a function of nutrient concentration
are few. Waite and Mitchell (Ref. 7) have demonstrated that increases in the concentration
of ammonia and phosphate significantly increase the rate of carbon fixation (photosynthesis)
in Ulva lactuca , a green macroalgae. In the red alga Eucheuma , periods of maximum growth
coincide with maximum nutrient concentrations during periods of lowered temperatures and
reduced light along the Florida coast (Ref. 8).

Jackson states in his PhD thesis that for natural kelp beds ( M. pyrifera) off San Diego
"the condition most hmiting Macrocystis production was the low concentration of dissolved
nutrients, especially nitrogenous substances, near the surface" (Ref. 9). Nitrate concentra-
tions in the San Diego Point Loma kelp bed were generally low, less than 1 ;ug-at/hter
NO3 - N* (Ref. 9), however, during upweUing periods can go as high as 5.8 jUg-at in the near-
surface (Ref. 10). There is evidence that M. pyrifera compensates for this nitrogen hmitation
by translocating it from depths where concentrations are significantly higher (Ref. 9). This
characteristic is very significant and should be considered when designing the upwelling and
distribution systems for the Ocean Farm.

Natural populations of M. pyrifera off southern Cahfornia experience nitrate concen-
trations on the surface from near ptg-at/hter to as high as 9 /ig-at/hter NO3-N, but generally
less than 4 /zg-at/liter. At 8-10 meters depth the concentrations are usually higher, varying
from about 1 /xg-at to as high as 16 with a mean range of 2-6 Mg-at NO3-N (Refs. 9 through
1 2). Nutrient concentrations are usually highest in the January to June period and lowest in
late summer. Growth rates have been observed to be decidedly low when dissolved nitrogen
falls below 1.0 Mg-at/hter (Ref. 13). Preliminary studies by W. North indicate that Kj^ for
NO3 (the concentration of nitrate at which the uptake velocity of nitrate is 1/2 maximum)

is near 9.4 Mg-at/liter (Ref. 13). Optimally, the concentration of nutrients should be above
the Kjj^ for maximal productivity. An area having a 10-15 /xg-at/liter NO3-N should yield a

very high growth rate. Above this concentration the uptake rate curve levels off, therefore.



*/ ng-at litter NO ^N =14 micrograms nitrate nitrogen/liter or 14 parts per billion (ppb).



Table 1 . Ocean Energy Farm : summary of site selection criteria.
BIOLOGICAL REQUIREMENTS/LIMITATIONS

1. 20° maximum mean surface temperature

2. a. 3-5 ^tg-at/liter nitrate (minimum)
b. 10-15 jug-at/liter nitrate (optimal)

3. a. 25 cm/sec (0.5 kn) current maximum OFEF {> 25 cm/sec sustained current

causes plants to approach horizontal at substrate depth)

b. Optimal: 10 cm/sec (0.2 kn)

c. Minimal: 4 cm/sec (0.08 kn)

ENGINEERING LIMITATIONS/REQUIREMENTS

1. a. 0.5-m/sec (1-kn) current at substrate depth (Phase 1 operational current)
b. Maximum 1.5-m/sec sustained current design limitation

2. a. Avoid storm-force winds (greater than 25 m/sec) (locate in area of least storm

probability)
b. Minimize gale-force winds (greater than 17-m/sec, 5.5-meter waves)

3. a. Maximum significant wave height 1 1 meters (35 feet) (design for Pliase 1 test

module)

b. Extreme wave height 19 meters (63 feet) (extreme design wave)

c. Minimum mean wave height 1 meter (required for upwelling system)
Optimal wave height 2-3 meters (for upwelling system)

ECONOMIC

1. Moored substrate - maximum depth 600 meters (Phase 3)

2. Proximity to research and support facihties

Phase 1 : 32-kilometers maximum (2-hour transit time)

GEOPOLITICAL

1 . Avoid traditional sea lanes and submarine transit zones

2. Locate outside claimed economic and territorial zones

(probably 320-kilometer zones will be adopted - needs international clarification)



providing the plants with greater than 15 /zg-at-N03-N would probably not be economical

(e.g., an increase from 16 to 23 jug-at/liter only causes an increase in uptake rate of 12 per-
cent, Ref. 13). Minimum levels of NO3 required for the marine farm are estimated to be
between 3 and 5 /ag-at/liter (an increase in uptake rate of 400 percent is computed when
NO3 levels are increased from 1 to 5 ^ug-at/liter from W. North data, Ref. 13), since average

levels of NO3 off the southern California coast at depths between 1 00 and 300 meters vary

from 15 to 30 /ig-at/liter. If the nitrate required by M. pyrifera is between 3 and 1 5 Mg"at/
liter, then the estimated amount of upwelled water to provide this level of nutrient to the
plants is between 10 and 50 percent assuming thorough mixing of upwelled with surface
waters. A very important parameter discussed by North (Ref. 13), is the percentage of
surface area of kelp that is exposed to given levels of NO3. This factor should be considered

in the design of the distribution system. If exposure area on the M. pyrifera can be maxi-
mized, then the concentration of NO3 might be reduced significantly while maintaining
adequate growth rates.

Temperature

In most biochemical systems, increases in temperature cause increases in chemical
reaction rates to some maximal temperature level beyond which inhibition occurs. Tempera-
ture is found to be very important in modifying kelp growth rate. Comparison of elongation
growth rates measured at different temperatures yield a Q\q* of approximately 1.7 for

M. pyrifera (Ref. 14). This indicates that the expected increase in frond elongation for a
10°C rise in temperature is by the factor 1 .7. However, M. pyrifera off southern Cahfornia
does poorly at temperatures above 20°C, and when above 25°C the symptoms of "tempera-
ture damage" (pigment loss, brittleness, sloughing) appear in a week or less (personal com-
munication, W. North).

Clendenning studied the effect of short-term exposures to high temperatures and
found that light-saturated photosynthesis was always highest between 20° and 25°C
(Ref. 15). At 30°C photosynthesis was completely inactivated within the first hour of
exposure in kelp collected from depths of 15 to 20 meters, and it was partially inactivated
in one hour in kelp collected from the surface canopy. In longer term experiments at
23.9°C (75°F). M. pyrifera showed a decrease in photosynthetic capacity after one day and
severe degradation of the plant after two days (Ref. 1 5). M. pyrifera from Bahia Tortugas,
Baja California, flourishes in water that reaches approximately 26°C for several weeks during
late summer (W. North, personal communication). Clendenning demonstrated that the
photosynthetic temperature optimum for the Turtle Bay kelp was between 25° and 30°C.
These plants also exhibited a 50-percent-higher photosynthetic capacity per unit area than
has been observed in local southern California kelp (Ref. 15).

Studies on the effect of temperature on M. pyrifera growth have not generally
included nutrient measurements. In the reported cases where there has been a summer
die-off of kelp, allegedly caused by higher than normal temperatures, nutrient data are



*Temperature coefficient. The increase in rate of a process (expressed as a multiple of initial rate) produced by raising the
temperature 10° C.



sparse or unavailable. Wanner surface water from the south is very low in nutrients, and
when there is an intrusion of this water along the southern California coast, it is possible, if
not probable that the plants suffer from nutrient deficiency rather than high temperature
degradation, or perhaps there is a synergistic effect. An experiment to investigate the com-
bined nutrient and temperature effects on the growth rate of M. pyrifera must be completed
to better define temperature and nutrient limitations and thus more accurately characterize
potential ocean farm geographic ranges.

The initial sustained temperature limitation is therefore tentatively put at 20°C.
Temperatures above this value appear to have a degrading effect on the kelp off southern
California and this area will probably be the first source of plants for early experimental
farms. The 20°C assumed hmiting temperature may eventually be increased if southern
(Bahia Tortugas) plants are used or if genetic manipulation in the future creates strains of
greater temperature tolerance. (Note: Figure 1 1 shows the approximate ranges of Macro-
cystis if limited to 20°C and with varying amounts of surface cooling from artificial
upwelling.)

Currents

The magnitude of the current field to which the proposed marine farm is exposed is
of great importance to its overall success. Currents of high velocities relative to the substrate
will entail high cost structures and will tend either to cause the kelp to trail horizontally at
or near the depth of the substrate, thus reducing light level and productivity. In extreme
conditions such currents might cause the plants to break away. In combination with high
waves they could cause damage to the substrate structure itself. Conversely, a low velocity
water movement is required to replenish nutrients in the vicinity of the plants and carry off
waste products.

Besides major current systems, other forms of water movement are important. These
include local wind-derived currents, swell and chop, internal waves, and natural and artificial
upwelling. Artificial upwelling may become very important as a water movement factor in a
large marine farm where the other forms may be severely diminished by the frictional char-
acteristics of the plants (Ref. 16).

Preliminary experiments at the University of California, Santa Barbara, indicate that
for tissue excised from adult Macrocystis , a maximum photosynthetic rate (ml O9 evolved/

cm'^ blade/hr) is observed with a water velocity of 10 cm/sec or approximately 0.2 knot (W.
Wheeler, personal communication). In several as yet unpublished experiments, W. Wheeler
utilized a variable flow-through system to measure the O9 evolution from Macrocystis tissue

while keeping nutrients and light levels constant. The rate of photosynthesis with no water
movement was measured to be approximately 1/5 that at 10 cm/sec. At a velocity of 4
cm/sec (0.08 knot) the photosynthetic rate was 1/2 maximum. It is apparent from these
experiments that some degree of water movement is required to increase nutrient availability,
and thus the rate of photosynthesis, above that supported by purely diffusive processes.



10



The optimum current velocity recommended for the Ocean Farm is 10 cm/sec
(0.2 knot). An absolute minimum sustained velocity of 4 cm/sec (0.08 knot) is recommended.
These recommendations are for mean water speed past the kelp plants and are tentative until
more thorough experiments can be accomplished. The important parameter is relative water
speed which can be the combined result of current, swell, internal waves, and upwelling. If
factors other than primary current create an adequate water flow, the site could successfully
be located in an area where current velocity is reduced below the levels listed above as mini-
mum. Some degree of water movement is necessary, however, to ensure an interchange of
nutrient-depleted, high-waste-concentration water with fresh water.

At the other extreme, sustained currents of relatively high velocity can be destructive
to the plants or cause them to trail horizontally, thus reducing their photosynthetic capacity
by reducing available light. Currents above 25 cm/sec (0.5 knot) tend to cause mature M.
pyrifera to trail towards the horizontal, approaching the depth of their substrate (W. North,
personal communication). For this reason, the maximum, mean sustained relative current
that can be tolerated within the marine farm is taken as 25 cm/sec.

ENGINEERING LIMITATIONS/REQUIREMENTS

The preliminary design criteria for a moored ocean farm grid system for Phase 1 and