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Marine Resources and Aquatic Technology Program (MRATP)
Research Interests of Marine Resources and Aquatic Technology Program (MRATP)MARICULTURE & BIOENGINEERINGPhillip G. Lee, Ph.D., and Chrystal Crain, B.S. Mariculture. The NRCC research program focuses on the laboratory culture of the squid Sepioteuthis lessoniana and the cuttlefish Sepia officinalis. These cephalopods are highly promising biomedical models because neurobiologists are interested in their brains, nervous system (e.g., giant axons) and sense organs and because we have produced multiple laboratory generations in our laboratory. Our objectives are to develop reliable and reproducible methods by which these cephalopods may be cultured from eggs through their life cycle under controlled conditions. These projects enable investigators to conduct ontogenetic and in vivo experiments on cephalopods of known age, parentage and background. This unique opportunity to use cephalopods has never before been available to the research community. Recently, interest in the molecular biology of the nervous system and physiology of a variety of other organ systems has increased significantly. Our first major success in squid mariculture was realized in 1981 with the squid Loligo opalescens. Since that time we have successfully cultured two other species of Loligo through the life cycle. However, for the past six years we have focused our efforts on developing the potential of the squid, Sepioteuthis lessoniana. This warm-water squid shows extraordinary growth to 2.2 kg in 6 months and is hardier than Loligo spp. squids. We consistently have adult squids in the laboratory and have cultured these squid through six laboratory generations. Squids 4 months old have giant axons larger than 450µm in diameter. We are now concentrating upon refining our culture methodology so that we can produce squids on a commercial scale. Our cuttlefish culture program has progressed rapidly over the last 7 years. After assessing the culture potential of Sepia officinalis, we have now turned our attention to their feeding behavior and nutrition. The research is organized into four areas: (1) feeding behavior, (2) chemical attractants, (3) palatability and digestibility and (4) growth trials. A major success in the research has been reached since we now have a diet formulation that not only functions as an acceptable maintenance diet, but promotes modest growth in juvenile and adult cuttlefish. These research projects have been funded by the NIH's National Center for Research Resources and the Texas Institute of Oceanography. Bioengineering. The NRCC is one of the most successful intensive mariculture laboratories in the world, and much of this success can be attributed to the advances made in closed, recirculating seawater systems. Cephalopods require high standards of water quality while feeding at high rates and producing copious quantities of ammonia and ink. In order to reduce the costs of operation and labor required to maintain recirculating systems, the NRCC has initiated a research program to develop automated control and expert systems for aquaculture. A computer automated control system has been installed and utilized to manage closed, recirculating seawater systems and associated filtration. Eventually, temperature, salinity, photoperiod, pH, dissolved oxygen, water flow, water level and nitrate concentration in all culture systems will be monitored and controlled. The system includes a patented denitrifying bioreactor for the control of nitrate levels in sea water. In addition, an expert system shell, using both rule-based and fuzzy logic, is currently under development in collaboration with UTMB's Center for Biotechnology and Bioengineering (Drs. Louis Sheppard and Hao Ying) and ORTECH Engineering, Inc., Houston, TX; this expert system will remotely control the aquaculture systems. Finally, a machine vision system to measure animal growth and activity has been developed and patented. These research projects have been funded by the Texas A&M National Sea Grant College Program and the Department of Commerce's Small Business Innovative Research Program. ETHOLOGY & ADAPTIVE COLORATIONF. Paul DiMarco, M.S. Studies of cephalopod behavior and the ecological context in which it occurs are being conducted on a variety of cephalopods. Combined field and laboratory studies are aimed at investigating species-specific behavioral traits in several species of squids, cuttlefishes and octopuses. For example, squids are highly interactive, social cephalopods, and they are continually communicating with one another through an impressive array of color patterns, postures and movements. We are now learning how these intraspecific encounters are used in aggression, in the establishment of dominance hierarchies, in mate selection, and in other ways, all of which are important to the life history of the species and to the survival and growth of these cephalopods in captivity. Special attention is being focused on reproductive behavior to improve the production of eggs for future laboratory generations. The diversified color patterns of cephalopods are species- and sex-specific, and all are closely associated with specific behavior. Ethograms are being constructed for several species to provide a basis for detailed quantitative analyses of brightness, color and pattern matching on diverse natural substrates. We are also experimenting with methods of classical conditioning to enhance the feeding response to our new pelleted diets. For the past 8 years an intensive field study of wild squid has been underway. Five expeditions have successfully documented the daily behavior patterns of the Caribbean Reef squid, Sepioteuthis sepioidea. Information from this field study will provide a better understanding of the behavioral needs of laboratory populations of Sepioteuthis lessoniana. Other studies have focused on foraging behavior of octopus living in reef habitats. Related to the laboratory and field studies of cephalopods, the NRCC has an extensive archive of photographic slides and video tapes of squids, cuttlefishes and octopuses, both in nature and in the laboratory. NUTRITION & PHYSIOLOGYPhillip G. Lee, Ph.D and F. Paul DiMarco, M.S. Cephalopods are the largest, most active invertebrates and there is considerable evidence for their convergent evolution with fishes. The driving forces are predation and shared food resources. Convergence with fishes is particularly evident in behavior, sensory systems and neuromuscular development; yet metabolism, ion balance and respiratory efficiency of cephalopods still share greater resemblance to bivalve molluscan relatives. Thus, cephalopods provide a transitional model for the study of bioenergetics and swimming performance in aquatic organisms. In cooperation with Dr. Ronald K. O'Dor, Dalhousie University, and Dr. Hans Otto Portner, Bremerhaven Institut for Polar and Marine Research, we have begun a survey of metabolism and energetics in cephalopods. Investigations at both the cellular and organ system level are being conducted. Cephalopod nutrition is of great practical and scientific interest to the NRCC. The design of prepared diets will remove one of the last barriers for practical cephalopod culture by reducing costs and allowing their culture inland. In addition, cephalopods are unique because they are 85% protein by dry weight and protein is the principal metabolic reserve and fuel for their obligate aerobic metabolism. Current research centers on their feeding behavior and the use of chemical attractants. This research has resulted in (1) the first quantitative evidence of chemotaxis in cephalopods and (2) the first successful defined diet formulated specifically for cephalopods. The next step will be to utilize these nutritionally defined diets and to investigate the amino acid metabolism of cephalopods. Cephalopods utilized amino acids for energy, locomotion, support, vision, oxygen transport, pigmentation and osmoregulation. These research projects have been funded by the NIH's National Center for Research Resources, Texas A&M SeaGrant College Program and NATO's Collaborative Grant Program. In addition to the cephalopod chemoreception studies, we have applied our testing protocol to crustaceans. This has led to the design of a feeding behavior model for aquatic organisms based on chemical stimuli. We have patented a crustacean feeding attractant AQUATTRACT™ and are currently testing its application for shrimp mariculture feeds. NEUROBIOLOGYWORK AT SEA & UNDERWATER ACTIVITIESThe Marine Biomedical Institute operates one small research vessel to conduct fieldwork and diving operations both locally along the Texas coast and throughout the Gulf of Mexico. The R/V Marie Hall, a 65-foot steel stern trawler equipped with modern navigational and collection equipment is used for a wide range of field studies. The ship is used primarily over the continental shelf to collect live squids with several types of trawl nets, with dipnets, and with night-light attraction methods. The vessel is also capable of transporting the live animals back to shore in several types of shipboard containers. Many of the food organisms, such as crabs, shrimps and fishes, that are needed in the squid and cuttlefish mariculture programs are also collected. An on-board compressor allows support of off-shore diving operations.
The NRCC maintains a research diving capability to support both its' laboratory culture program for squids, cuttlefishes and octopuses as well as field biology and behavior research. Diving is necessary to collect viable eggs of especially squids but also cuttlefishes and octopuses.
This division also works with other research groups on a national and international level to conduct field research on cephalopods. Field research has emphasized the use of research divers but other technologies such as ROV's and manned submersibles have also been utilized. Extensive use of u/w video recording is utilized to document the natural field behavior of target species including Sepioteuthis lessoniana, Sepioteuthis sepiodea, Loligo opalescens, Sepia latimanus, and Octopus cyanea.
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Research Diving and U/W Projects.
