Producing Marine Snails for Biomedical Research

The Aplysia Mariculture Laboratory

This state-of-the-art laboratory on Virginia Key, Fla. was designed specifically for culturing Aplysia californica. Since this animal is not indigenous to South Florida and is, in fact, native to a temperate climate the laboratory has been designed for extensive temperature manipulation, and 'fail-safe' operation.

Cultured animals are produced under a consistent regimen of feeding, temperature, photoperiod and other variables, which supports basic biomedical research by providing investigators with sufficient numbers of experimental animals from all developmental stages and sizes. Over the past twelve months, the facility has shipped over 30,000 animals to researchers around the world.

Control System

Water system- in order to maintain water temperature and quality, the lab's water system is equipped with a digital monitoring system which senses temperature, water level, pump function and triggers an alarm which indicates any unsatisfactory condition. The control system automatically switches to backup equipment to maintain preset operating conditions. Seawater temperatures that exceed the set point cause the control system to bypass the laboratory troughs until chiller operation returns to normal. Monitoring system maintains permanent records of temperature and flow conditions on a 24-hour basis. The laboratory also contains a separate analytical laboratory and shipping area.

Rearing Procedures

The Facility cultures animals under standard conditions from egg to adult. Rearing procedures have been optimized to produce large batches of siblings, so that inter-individual variation is reduced for those researchers needing a consistent genetic background within cohorts.

Fertilized eggs are collected daily from breeding pairs held on the premises. Several thousand animals (siblings) are produced from each collected egg mass. Throughout their growth and development, siblings are tracked with respect to egg mass (parents' identity), as well as hatching and metamorphosis dates, thus ensuring consistent genetic make-up and accurate age classing of each batch of animals shipped.

Eggs are incubated under constant conditions in the Larval Culture Lab until hatching. The free-swimming veliger larvae are then kept in sterile media for about six weeks until they are competent to undergo metamorphosis. Following metamorphosis, Stage 11 juveniles (1-2mm length) are moved to the Growout Lab where they are kept in chilled, ambient seawater troughs and fed a red seaweed diet. In the Growout Lab, animals may increase in mass 100,000 times (from 2 mg to 200 gm) in about six months. Animals of all sizes are shipped, including early stage, post-metamorphic juveniles useful in developmental studies and cell culture.

Producing Macroalgae

The successful laboratory culture of many marine invertebrates depends upon consistently providing the appropriate nutritional source for the various stages of the organism's life cycle. For Aplysia californica, seaweeds play two essential roles: the induction of metamorphosis at the end of the planktonic stage, and post-metamorphic nutrition for juveniles and adults.

Intensive Culture

Intensive seaweed culture was the only option with the potential to support the food and metamorphic requirements year round. Serendipitously, the facility was moved to its present location in Miami in the fall of 1988. Light and temperature no longer limited outdoor cultures and large-scale food production became a reality. Numerous isolates of Gracilaria, Agardhiella and a local species of Laurencia were all evaluated for growth and sustainability of vegetative strain in large-scale culture (reproductive strains will produce gametes and in some cases the plants are lost). A South Florida vegetative strain of Gracilaria ferox, (Strain SB), supported metamorphosis and growth as well as year round biomass production. Trials during the past eight years have resulted in a maximum production of 1,000 lbs/week in May/June and 400 lbs/week during February. Yearly production has reached 12 tons, more than is needed for the sea hare culture. Notably, all production came from an original inoculum of less than 10 pounds and has not been out-sourced since the initial culture.

The macroalgae facility provides the 12 tons of the red seaweed Gracilaria needed yearly to feed animals in the Aplysia Growout Lab. Continuous experimentation has resulted in maximizing yields of seaweed throughout the year. The system consists of seven, 2,400-gallon fiberglass tanks supplied with filtered seawater at a rate of 10 gal/min. Radiant energy and temperature are monitored constantly and algal growth rates are optimized by adjusting nutrient levels weekly.