Microalgae are the foundation supporting much of the marine food chain, and they are the natural food of filter-feeding organisms. Algae are therefore essential for production of live feeds for larviculture of finfish and shrimp. Thousands of species of microalgae are known to science. They present an enormous range of cell sizes, cell structures, biochemical constituents that determine their nutritional value and digestibility, and they also vary widely in ease of culturing. Microalgae can be very difficult, even impossible to identify to species based on light microscopy alone, and different strain isolates that appear identical may exhibit very different biochemical profiles or behavior in culture. Careful consideration is therefore necessary in order to select the most suitable strains for different larviculture applications. Although many microalgae strains have been tested as feeds, only about 20 are in widespread use. What follows can be no more than a brief overview of the how these algae are most commonly used in larviculture.

1. M
icroalgae are the foundation supporting much of
the marine food chain, and they are the natural
food of filter-feeding organisms. Algae are therefore
essential for production of live feeds for larviculture
of finfish and shrimp. Thousands of species of microalgae are known
to science. They present an enormous range of cell sizes, cell
structures, biochemical constituents that determine their nutritional
value and digestibility, and they also vary widely in ease of culturing.
Microalgae can be very difficult, even impossible to identify to
species based on light microscopy alone, and different strain isolates
that appear identical may exhibit very different biochemical profiles
or behavior in culture. Careful consideration is therefore necessary
in order to select the most suitable strains for different larviculture
applications. Although many microalgae strains have been tested
as feeds, only about 20 are in widespread use. What follows can
be no more than a brief overview of the how these algae are most
commonly used in larviculture.
Rotifers
The rotifers used in aquaculture (species of the genus Brachionus)
are capable of ingesting particles as small as bacteria and as large as
10–30 µm; larger rotifers are capable of ingesting correspondingly
larger particles. Bacteria are too small to provide a significant source
of nutrients, with the possible exception of vitamins (e.g. B12). Rotifer
digestive systems are equipped with a unique grinding apparatus (mas-
tax) that can mechanically disrupt yeast or algae cells, enabling rotifers
to thrive on algae that may not be digestible by other filter-feeders.
Rotifers can ingest inert particles, and yeast has often been used as an
inexpensive feed to maintain rotifer cultures. But the nutritional value
of rotifers as live feed for larval fish or shrimp is determined by the
quality of the feed used to produce the rotifers, and only algae feeds
can support high-density rotifer populations with optimal nutritional
profiles.
Many of the algae commonly used in aquaculture have been used to
successfully culture rotifers, at least for experimental studies, but by far
the most commonly used algae are strains of Chlorella, Nannochloropsis,
and Tetraselmis. These algae can be produced reliably and at relatively
low cost, but none can produce rotifers with an optimal nutritional
profile for many larvae. Their most conspicuous shortcoming is the
essential HUFAs (Highly Unsaturated Fatty Acids) content, in particular
EPA and DHA, which for many fish are particularly important for nerv-
ous system development. Chlorella in particular lacks HUFAs, although
it can support excellent growth of rotifers. Nannochloropsis contains
high levels of EPA, and Tetraselmis moderate levels; both can support
excellent rotifer growth, but neither contains DHA. A Japanese com-
MicroalgaeDifferent types of algae provide vital nutrients to rotifers,
copepods and larvae of finfish, shellfish and shrimp
by Dr Eric Henry, PhD, Research Scientist, Reed Mariculture Inc
30 | INTERNATIONAL AQUAFEED | September-October 2015
FEATURE

2. pany offers Chlorella that has been infused with DHA. However, the
sterol profile of Chlorella, like many other green algae such as Dunaliella
and Haematococcus, lacks cholesterol. Rotifers produced to feed
shrimp or crab larvae should instead be fed Nannochloropsis, which will
provide the cholesterol that is essential for these crustaceans.
Copepods
A diverse array of different copepod species are used in larviculture,
and they vary in their capacity to thrive on different algae. Some require
different algae at different stages of development. The most commonly
used algae are strains of the flagellates Isochrysis and Tetraselmis, and
the diatoms Thalassiosira and Chaetoceros. Some strains of Isochrysis
(most often the “Tahitian strain” or “T-Iso,” which has been recently
recognised as the new genus Tisochrysis) have supported growth and
development of some copepods through the entire life-cycle, but other
copepods require additional strains in their diet. This may be explained
by the fact that although Tisochrysis is widely used in aquaculture due
to its high levels of DHA, it lacks cholesterol, and some copepods have
the specific requirement for cholesterol that has been documented in
many other crustaceans.
Diatoms, especially strains of Thalassiosira and Chaetoceros, have
seen wide use in copepod culture, although some studies have
concluded that “diatoms” can harm copepods, or that a diatom diet
requires supplementation with cholesterol. Such broad generalisations
ignore the great biochemical diversity among diatoms; for example,
very few contain significant cholesterol, but some of these can have
high levels.
Bivalves
Although bivalve aquaculture relies on natural phytoplankton for
market production, cultured algae are essential for larviculture in
hatcheries. Cultured algae are also often used for “nursery” culture
of spat and later juvenile stages, and for improving the condition of
broodstock for spawning. The algae most widely used for bivalves
include strains of Nannochloropsis (mostly for mussels), the diatoms
Thalassiosira and Chaetoceros, and the flagellates Tetraselmis, Isochrysis
(including Tisochrysis) and Pavlova.
Pavlova strains are known to have a high HUFA content. In addition,
there is a widespread impression among bivalve hatchery operators
that Pavlova imparts an unknown “special” benefit as a larviculture feed,
and hatcheries expend extra effort to provide Pavlova despite frequent
culture difficulties. It may be that the peculiar beneficial effects are not
due to the HUFA content, which is not markedly different from what
can be provided by combinations of other algae. Different Pavlova
strains contain a remarkably diverse range of unusual sterols. Research
with scallop larvae indicates that several Pavlova strains produce a sterol
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September-October 2015 | INTERNATIONAL AQUAFEED | 31
FEATURE

3. that is a structural analog of an arthropod molting hormone, ecdysone,
and it induces metamorphosis in larvae. This is a very unexpected
phenomenon, and it is a reminder that there remain many gaps in our
knowledge of how microalgae may affect the biology of bivalves.
Shrimp
Shrimp aquaculture exploits a variety of shrimp and prawn species,
many of which have been the subject of larval feeding studies. Caution
is therefore required when generalising findings to all shrimp, but some
useful conclusions can be drawn.
Larvae of shrimp naturally feed primarily on microalgae, and use
of algae as sole feed or co-feed with larger prey can often be ben-
eficial well into postlarval stages. The most commonly used algae
are strains of Isochrysis Tetraselmis, Thalassiosira and Chaetoceros.
Because most shrimp production is carried out in very large-scale
culture systems, very large amounts of algae are required, putting a
premium on algae capable of maintaining high growth rates under
mass-production conditions. Diatoms have proved to perform
particularly well in shrimp facilities. This may be attributable in large
part to the fact that the silica cell wall of diatoms functions as a
pH buffer at the cell surface, enhancing the activity of extracel-
lular carbonic anhydrase, the enzyme that converts bicarbonate to
carbon dioxide. This mechanism greatly enhances photosynthesis in
the relatively high pH (8.5 and above) prevailing in vigorous algae
cultures.
Finfish
When larval fish consume live zooplankton prey, they are gaining
nutrition that origi-
nated from the feed
consumed by the live
prey, most often algae.
However, an addition-
al, often overlooked
contribution from
algae is direct con-
sumption of algae by
the larvae. No doubt
some of the beneficial
effects of “greenwa-
ter” (addition of algae
to larviculture tanks)
can be attributed to
consumption and
assimilation of algae by
larvae, as has been demonstrated in cod, turbot, halibut, and clownfish.
Other beneficial effects of algae have been reported, such as stimula-
tion of digestive activity and immune responses. Suppression of toxic
Vibrio bacteria by Tetraselmis and Isochrysis has also been reported.
Nannochloropsis is the most commonly used greenwater alga,
because of its low cost and small cell size that imparts a low sinking
rate, which ensures that it remains in suspension. It is also an excel-
lent feed for the rotifers often used as first-feed for larvae, helping to
maintain the nutritional value of the rotifers until the larvae can con-
sume them. But Nannochloropsis contains no DHA, and is difficult for
many organisms to digest, so other larger-celled and more digestible
algae such as Tisochrysis with its high DHA content, or algae such as
Tetraselmis with its significant taurine content, may prove to function as
more effective as feeds for larvae.
How to choose optimal algal feeds?
Although various nutritional components have been documented in
many algae strains, complete nutritional profiles are known for very few
of them, so it can difficult to predict which strains are the best choices
for a particular application. It is unfortunate that so many studies of
the nutritional performance of microalgae have tested only one or
two strains in each trial, because one or two strains are unlikely to
provide an optimal nutritional profile comparable to that provided by
the natural mixed phytoplankton assemblages that filter feeders have
evolved to exploit.
It is equally unfortunate that so many feeding studies have failed
to clearly identify the particular strains of the algae that were used.
Although the HUFA contents of many strains have by now been well-
documented, sterol profiles have been more challenging to character-
ize because there is far more strain-to-strain variation, even among
strains supposedly of the same species. Additional uncertainties arise
because the nutritional profiles of even well-known strains of micro-
algae can be strongly influenced by culture conditions, including light
regime, temperature, nutrient (e.g. nitrogen, phosphate) availability,
and the growth phase of the culture (exponential, stationary, declining)
when harvested. All these sources of variability in the nutrient value of
algae can lead to apparently contradictory findings among studies using
ostensibly the same algae.
Nevertheless, these findings are not useless. Reports of the efficacy
of certain strains of algae are likely to indicate the most promising can-
didates for subsequent trials. Successful trials establish that the strains
can provide good nutrition. Contradictory negative results are then
most likely to indicate that failure was caused by some unidentified
factors in the trials, not the intrinsic qualities of the strains. Much work
remains to be done, but well designed feeding studies will continue to
refine our understanding of how algae can be used more effectively in
larviculture.
www.reedmariculture.com.
32 | INTERNATIONAL AQUAFEED | September-October 2015
FEATURE

5. R
eed Mariculture Inc (RMI) was
founded in 1995 by Tim Reed to
grow "tank raised" bivalve shellfish.
Tim's concept was to produce the
first commercially available shellfish that was
raised on land, not in the ocean, producing a
product that would be completely safe from
toxins such as red tide algae, bacteria blooms,
viruses, sewage run-off, and toxic metals.
Reed Mariculture developed tank raised
shellfish technology for three years and during
this same time developed and refined the
technology for large-scale grow out of marine
microalgae, which is the feed for shellfish.
In 1998 RMI determined that there was a
more lucrative market in selling the microalgae
directly to other hatcheries and shut down all
shellfish operations. RMI's core technology is
a proprietary closed-system photobioreactor
design that allows microalgae to be grown
in laboratory sterile conditions. This technol-
ogy is radically different than the open-pond
technology used for growing freshwater spe-
cies of microalgae such as Spirulina, Chlorella,
Haematococcus, and Chlamydomonas.
In 2003, RMI expanded its product focus
from microalgae to a broader range of larvi-
culture products with the introduction of live
zooplankton (rotifers, copepods, and Mysid
shrimp) and by distributing products such
as ClorAm-X® (for ammonia control) and
Otohime Feeds (Japanese weaning diets).
In 2004, RMI entered the home aquarium
market with the introduction of the Phyto-
Feast® products. Phyto-Feast is a super con-
centrate of marine microalgae formulated for
feeding exotic filter feeders such as clams,
corals, sponges, and tunicates that are popular
in marine reef tanks.
In 2005, RMI expanded their offerings
into the Marine Ornamental industry with
the Reef Nutrition product line. This product
line includes marine microalgae, macroalgae,
rotifers, copepods, mysid shrimp.
Reed Mariculture is now the world's larg-
est producer of marine microalgae concen-
trates. The Instant Algae® larviculture feeds
are used by over 500 hatcheries, universities,
and marine ornamental operations in more
than 70 countries around the world. We also
produce zooplankton, copepods, and weaning
feeds.
I was able to talk at some length with RMI
founder, Tim Reed about what captivated his
interest in aquaculture and how his passion
has been the main driver behind the expan-
sion of Reed Mariculture Inc from its origins in
1995 to where it is today.
IAF: Could you tell us a little bit about your
background and what sparked an interest in
the aquaculture industry?
TR: What sparked my interest was discovering
the amazing taste of razor clams! After college
I was working on a factory trawler and on a
trip to Chile I was introduced to razor clams.
That fueled a dream to start a land-based farm
to grow high-value bivalves to sell into the
San Francisco market, which required large
amounts of marine microalgae.
IAF: You set up and founded Reed
Mariculture in 1995. The company is now
the world’s largest producer of marine
microalgae concentrates used by over 500
hatcheries in more than 90 countries. Can
you tell us a bit more about the genesis of
the company and its evolution?
TR: When Reed Mariculture Inc (RMI) was
founded in 1995, my goal was to produce the
first commercially available, biosecure shellfish
raised on land. We developed tank-raised
shellfish technology for three years, and during
this same time we developed and refined the
technology for large-scale grow-out of marine
microalgae - the feed for shellfish.
RMI's core technology was and remains to
this day a proprietary, closed-system photo-
bioreactor design that allows microalgae to
be grown in controlled conditions. In 1998 we
determined that selling our microalgae directly
to other hatcheries was a more lucrative
market, and we shut down all shellfish opera-
tions. We innovated a line of refrigerated
microalgae concentrates for hatcheries called
Instant Algae® that provide “algae when you
need it™.”
In 2003 we expanded our larviculture product
line with the introduction of live zooplankton
(rotifers, copepods, and mysid shrimp), and by
distributing products for ammonia control and
Japanese weaning and juvenile diets. In 2004
RMI entered the home aquarium market with
the introduction of the Phyto-Feast® prod-
ucts-super-concentrates of marine microal-
gae formulated for feeding coral, clams and
other popular, marine reef tank filter feeders.
We expanded into the marine ornamental
industry with the Reef Nutrition® prod-
uct line, which includes marine microalgae,
macroalgae, rotifers, copepods, Mysis shrimp
and other feeds. In 2011 Reed Mariculture
launched a new product line, APBreed™, to
provide customised solutions for the unique
needs of aquarists, propagators and breeders
based on our advanced hatchery products.
IAF: A passion for the uses and applications
of algae in aquaculture obviously lies at the
heart of your work. Can you tell us more
Q&A
with Reed Mariculture
Inc founder and
President Tim Reed
by Olivia Holden, International Aquafeed Magazine
Microalgae
34 | INTERNATIONAL AQUAFEED | September-October 2015
FEATURE

6. about the process of how microalgae is
grown?
TR: Unlike traditional algae systems, we use
proprietary, closed, recirculating photobio-
reactor design that allows microalgae to be
grown in controlled conditions, miles from
any vectors of contamination. Our proprietary
harvest and concentration processing then
retains intact whole cells that retain all their
nutritional value, while at the same time ren-
dering them non-viable.
IAF: What comprises your current product
range and applications?
TR: We are the plankton people - both
microalgae and zooplankton. We grow and
supply hatcheries with a variety of marine
microalgae-based feeds for many types of
larvae, including finfish, bivalves, crustaceans
and ornamentals. We also supply microalgae
for rotifers and copepods to nourish finfish
and other larvae. In addition, we grow and
supply three strains of live rotifers and three
strains of live copepods, and supply mysid
shrimp and artemia.
We are known for our Instant Algae prod-
ucts that provide “algae when you need
it.” Instant Algae has all the advantages and
characteristics of live algae without the large
investment of infrastructure, time and labor
required to grow it yourself. These biosecure
concentrates and custom blends of the most
effective algae for larvae growth and survival
can be used as a complete feed replacement
or as a nutritional supplement, and provide
insurance against a crash. The algal cells are
non-viable but intact whole cells that retain all
their nutritional value, which in turn provides
maximum nourishment to the larvae. We also
supply eight species of algae including four
species of diatoms, plus Isochrysis, Tetraselmis,
Pavlova and Nannochloropsis.
For finfish, our RotiGrow® product line
includes three all-in-one growth and enrich-
ment feeds with varying levels of DHA. The
nutrition from the algae in these products is
incorporated into the tissue of the rotifers,
not merely the gut, and the whole, intact
cell of the microalgae encapsulates all of the
nutrients, resulting in a cleaner tank, less waste
and greater value. For bivalves, we produce
Shellfish Diet®, a superior feed that is a blend
of algae for broodstock maturation, first feed-
ing larvae, setting and spat grow-out.
As a complement to the feeds we grow
and produce, we also carry a number of
support products including Otohime - a high
quality Japanese larval weaning and juvenile
feed, TDO Chroma Boost™, a pellet fish
food "top-dressed" with Haematococcus for
vibrant color and superior nutrition, as well as
ClorAm-X® for ammonia control and a small
assortment of specialty zooplankton growing
equipment.
IAF: What products do you offer specifically
for shrimp, one of the biggest exports in
Asia-Pacific?
TR: Several of our single-species Instant Algae
concentrates are used in shrimp produc-
tion: Thalassiosira weisflogii and pseudo-
nana, Chaetocerous “B” and calcitrans, and
Tetraselmis. All provide “algae when you need
it,” in the form of clean, bio-secure nutrition
for shrimp. Instant Algae is currently most
often used as a biosecure supplement to algae
grown on site, but we are currently working
on the development of blended algal products
nutritionally optimised to be available as a
complete algae replacement.
IAF: You also supply to the home and com-
mercial aquarium market. What is exciting
about this for you?
TR: Not everyone realises that the needs of
home and public aquariums are very similar
to the needs of hatcheries. They all need
microalgae and zooplankton, which is what
we specialise in. We provide clean, biosecure,
microalgal and zooplankton feeds that are
convenient and easy for home hobbyists and
aquariums to use. What is really exciting is
how our feeds are helping cutting-edge fish
September-October 2015 | INTERNATIONAL AQUAFEED | 35
FEATURE

7. and ornamental breeders, who are trying to
commercialise various hard-to-raise animals
and expand the markets for them. Their suc-
cesses will ultimately result in greatly reducing
or eliminating the need for wild capture and
its devastation of natural habitats.
IAF: In what way does Reed Mariculture
work with academics and Universities to
further and share knowledge?
TR: We supply feed to hundreds of university
programs that are pushing the envelope in
aquaculture technology. They are never shy
about giving us feedback on how we can
improve our products and telling us what their
unmet needs are. We have developed and
maintained close, collaborative relationships
with these programs for decades.
IAF: Client care and technical support lies
at the heart of any successful business. How
does Reed ensure this is achieved?
TR: We pride ourselves on our customer
service and are committed to going above
and beyond to support our customers -
whether it’s to get the product out in a timely
way to hard-to-reach locations, providing
technical assistance in emergency situations,
or collaborating with customers to develop
custom blends to meet their animals’ specific
nutritional requirements. We refer all techni-
cal questions to our phycologists and live
feed specialists who take the time to answer
questions. We also solicit feedback from our
customers to ensure that we are meeting or
exceeding their needs.
IAF: Sustainability is obviously a very press-
ing issue as the demand for more food
grows. How is Reed Mariculture engaging
with sustainability?
TR: As the supply of fish and shellfish,
and more importantly larvae and seed
from the wild, become harder to come by,
aquaculture is going to increasingly turn to
land-based hatchery larviculture for tradi-
tional food sources and new species. Reed
Mariculture has the clean, highly nutritious
feeds that are needed to support this transi-
tion. We also see ourselves playing a role in a
future with healthier reef ecosystems. When
ornamentals aren’t predominately collected
from the wild, creating massive damage to
delicate reef life, but are increasingly raised
in hatcheries and farms, reefs can be saved
from destruction, opening up the possibility
of restoration.
In terms of our own production from a sus-
tainability point of view, our closed, recirculat-
ing systems are highly efficient. We have near
-0- wastewater, and no discharge. Traditional
open pond and batch culture systems lose
considerable amounts of water through evap-
oration, and there are not always effective
means for cleaning residual water and making
it reusable. As aquaculture grows to meet
the requirements of the coming decades, the
ability to produce algae sustainably will be
critically important.
IAF: What do you perceive to be the biggest
challenges facing the aquaculture industry
today?
TR: The biggest challenges across all sectors of
aquaculture are: increasing hatchery produc-
tion, improving hatchery technology, and the
availability of high quality, healthy, clean larvae/
seed that will perform well in grow-out.
IAF: And finally, what is the one piece of
advice you would give anybody looking to
work in the aquaculture field?
TR: Aquaculture is a special community of
“scientist farmers” who thrive on innovating,
nurturing and getting their hands wet. If this
kind of thing is your passion, aquaculture can
be the most rewarding adventure of a lifetime.
"Aquaculture is a special
community of “scientist farmers”
who thrive on innovating,
nurturing and getting their
hands wet. If this kind of thing
is your passion, aquaculture
can be the most rewarding
adventure of a lifetime"
36 | INTERNATIONAL AQUAFEED | September-October 2015
FEATURE

8. September-October 2015 | INTERNATIONAL AQUAFEED | 37
FEATURE
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