Quickstart Rotifer Cyst Collection Guide

How to exploit a large range of Brachionus biodiversity in aquaculture

Rotifers produce diapausing or resting eggs called cysts that can survive freezing temperatures, desiccation and long-term storage. Upon re-hydration, the cysts will hatch in 24 hours into live rotifers and begin feeding, growing, and reproducing.

For aquaculture, cysts represent a convenient way to store rotifers and re-start cultures, as pouches can be stored for many years and hatched on demand.

We stock cysts from 15 rotifer species  packaged in long lasting pouches that store in the freezer for years. 

We guaranty the quality of these rotifer cysts, with minimal variability between batches in hatchability, uniform genetic purity of the species, and no contamination with ciliates. We further guaranty a shelf life of at least one year when cysts are stored at -20°C.

Background:

Rotifers are produced in most hatcheries in batch or semicontinuous cultures that are fed live or preserved microalgae. The intent of hatchery managers is to maximize the production of rotifer biomass in large, open tanks. A variety of bacteria, fungi and ciliates typically colonize these tanks, the composition of which is uncontrolled. Sooner or later undesirable contaminants colonize the tanks, and rotifer production declines. As a result, tanks need to be drained, cleaned, and re-started to restore production levels. It is critical that the rotifer inoculant for this upscaling be free from contaminants so that new populations can achieve maximum growth rates. Rotifers obtained by hatching cysts are contaminant-free and hatch into females that begin rapid asexual reproduction. Our experience has been that most contaminant problems and mass culture crashes can be avoided if rotifer cultures are periodically renewed from cyst inocula. The frequency of restarting from cysts may vary depending upon hatchery protocols, but restarting every few weeks to every few months will generally keep cultures clean, vigorous and contaminant-free.

The speed of this upscaling enables hatchery managers to grow rotifer mass cultures only when needed. Otherwise, rotifer stocks can be kept dormant in a freezer, requiring no maintenance and with no risk of contamination. Periodically using rotifer cyst inocula enables aquaculturists to maintain tight control over the genetic composition of their rotifer species. Mass cultures close to the sea are especially prone to colonization by wild zooplankton. Even the best tank management practices cannot keep species propagated by serial dilution free of contamination through years of culture. This can lead to shifts in rotifer body size as one species replaces another in mass culture tanks. Our experience has been that small rotifer species are particularly vulnerable to invasion and replacement by larger species. Returning to reliable cyst inocula periodically insures that the best rotifer species is provided to larval predators.

Advantage of Different Rotifer Species:

Rotifers with different body sizes are utilized for larviculture of fish based on their corresponding mouth gape sizes. Using appropriate size rotifer strains for marine finfish larviculture to a large extent determines its success. The key to being able to supply enough rotifers of different sizes in hatcheries is maintaining separate, uncontaminated mass cultures of different species.  It is quite feasible to mass culture multiple rotifer species in one hatchery if cultures are inoculated from rotifer cysts of known genetic composition.

A variety of Brachionus species currently are utilized in European hatcheries. One reason for deploying different Brachionus species is that they have markedly different optimal growing conditions. Over the geographic range from Norway to Greece, each fish hatchery has a unique set of environmental conditions and style of operation. Choosing the best adapted among several Brachionus species, makes it more likely that hatcheries will be able to closely match their rotifer production to their growing conditions and the needs of their larval predator.  The Brachionus diapause egg collection makes a large range of rotifer biodiversity easily accessible to aquaculturists in a form that is cost-effective, reliable, and free of contaminants.

 QuickStart Rotifer Cyst Collection:

The current Brachionus cyst collection is available  consists of seven different brachionid species.  (Table 1). These include four B. manjavacas (Fontaneto et al. 2007) geographical strains, five B. plicatilis Muller strains (Mills et al. 2016), two B. rotundiformis Tschugunoff strains, and one strain each of four more Brachionus species. These were collected over many years from a variety of habitats including inland salt lakes, coastal marine environments, and freshwater ponds. Adult females range in average length from 88 µm for Proales similis De Beauchamp to 305 µm for the B. plicatilis Tokyo strain.

Cysts in this collection were all produced in a laboratory under standard environmental conditions of 25°C, 15 ppt salinity, a diet of Tetraselmis suecica, constant aeration, and constant fluorescent light from two 20W cool white tubes. Supplemental feeding was provided by the commercial rotifer feed Amplifeed Replete. Rotifers were grown in batch cultures in 5-240 L plastic bags in about a two week growth cycle.

 Table 1. Characteristics of rotifers in the Brachionus cysts collection. Length and width are adult females without eggs.

Strain	Species	Collection Location	Habitat	Length (µm)	Std Dev	Width (µm)	Std Dev
Bm RUS	Brachionus manjavacas	Azov Sea, Russia	coastal marine	254.33	17.93	201.68	14.41
Bm Petta	Brachionus manjavacas	Pettaquamscutt, RI	coastal brackish pond	244.61	11.1	200.25	7.03
Bm MAN	Brachionus manjavacas	Manjavacas, Spain	inland salt pond	244.43	14.57	197.9	12.44
Bm Gaynor Pond	Brachionus manjavacas	Gaynor Pond, CO	inland salt pond	245.21	19.11	202.36	22.61
Bp Posa Sur	Brachionus plicatilis	Torreblanca, Spain	coastal brackish pond	270.68	24.16	209.76	13.13
Bp China	Brachionus plicatilis	Tiajin, China	coastal salt pond	260.69	19	208.73	11.55
Bp Tokyo NH1L	Brachionus plicatilis	Mie, Japan	eel culture pond	304.94	20.03	222.03	24.16
Bp SAL	Brachionus plicatilis	Salebrejo, Spain	inland salt pond	246.13	14.36	193.22	12.17
Bp AUPEA006	Brachionus plicatilis	Pearse Lakes , Australia	coastal brackish pond	224.06	17.3	174.13	18.32
Br HAW	Brachionus rotundiformis	Hawaii	aquaculture facility	163.46	13.85	134.72	8.86
Br Italy	Brachionus rotundiformis	Adriatic, Italy	coastal marine	136.91	15.53	113	9.06
JPN S-type 2014-ES	Brachionus sp. JPN S-type	?	Japanese fish hatchery	144.45	9.13	125.21	7.76
Nev2	Brachionus "Nevada"	Little Fish Lake, Nevada	inland salt lake	246.44	10.26	195.41	14.79
LL1	Brachionus sp. "Almenara"	Lost Lake, CT	coastal brackish pond	232.16	18.95	194.84	11.01
Bc GAINES	Brachionus calyciflorus	Gainesville, FL	freshwater pond	215.96	24.29	147.97	12.5

 

Literature Cited:

Fontaneto, D., I. Giordani, G. Melone & M. Serra, 2007. Disentangling the morphological stasis in two rotifer species of the Brachionus plicatilis species complex. Hydrobiologia 583: 297–307.

Hagiwara A. and H. Marcial. 2019. The use of non-Brachionus plicatilis species complex rotifers in larviculture. Hydrobiologia 844:163–172.

Hoff, F.H. and T.W. Snell. 2004. Plankton Culture Manual. 6th edition, Florida Aqua Farms, Dade City, Florida.

Mills, S.,  J. A. Alcantara-Rodrıguez,  J. Ciros-Perez, A. Gomez,  A. Hagiwara, et al. 2016.  Fifteen species in one: deciphering the Brachionus plicatilis species complex (Rotifera, Monogononta) through DNA taxonomy. Hydrobiologia, DOI 10.1007/s10750-016-2725-7

Snell TW, RK Johnston, AB Matthews. 2018. Utilizing Brachionus biodiversity in marine finfish larviculture. Hydrobiologia, DOI 10.1007/s10750-018-3776-8.