Researchers demonstrate the feasibility of using detritus as food for small crustaceans in aquaculture

Researchers at the University of Seville, in collaboration with the Institute of Agricultural Research and Training and Fisheries (IFAPA) have analyzed the diet of two types of caprellids, tiny marine organisms that serve as food for fish. Results found that they are able to reuse the feces of other species, which makes them a sustainable and affordable option for aquaculture industries.
June 30, 2016

Researchers belonging to the Marine Biological Laboratory at the University of Seville, in collaboration with the Institute of Research and Agricultural and Fisheries Training (IFAPA), Caprella group have found that fish detritus provides an adequate diet for two types of caprellids, tiny marine crustaceans destined for aquaculture. Experts point out that this ability to take advantage of waste from other species for food makes the species a sustainable and affordable alternative to species currently in use.

Caprellids are crustaceans between two millimeters and two centimeters in size that resemble a praying mantis. They are essential in the diet of many fish in nature, and they also constitute an important part of the diet of some cephalopods such as cuttlefish. Experts from the University of Seville point to their advantages as feed in aquaculture due to their high levels of beneficial fatty acids and rapid growth.

However, researchers had not previously studied their diets or their role in the development of sustainable aquaculture techniques. \"Currently, the industry is seeking alternative feeding living organisms to include in integrated multi - trophic aquaculture, i.e., strategies where some species feed on the waste of others. Caprellids are excellent candidates because they benefit from the detritus formed from uneaten food and feces released by cultured fish,” explains the Foundation Discover scientist in charge of the study, José Manuel Guerra of the University of Seville.

In this sense researchers have determined in the study \'Towards Integrated Multi-Trophic Aquaculture: Lessons from Caprellids (crustacea: Amphipoda)\', published in the journal PLoS One, that the detritus of fish provide an adequate diet for these small crustaceans, compared with other traditional diets, such as brine shrimp or phytoplankton. \"In particular, it can be considered optimal feeding for caprellids adults, providing a source of omega-3 and omega-6. The young, however, seem to require an additional contribution of food for juvenile stages to grow properly, \" specifies Guerra.

So far, Artemia has been the most popular live food for fish larvae. However, scientists are focusing on identifying appropriate diets to replace these amphipod crustaceans and, therefore, reduce production costs in the aquaculture industry. The studies began with the thesis of Elena Baeza, and defended, and continue today with the doctoral thesis of Pablo Jimenez, both researchers at the Caprella group.

In their search for alternatives, experts evaluated the nutritional content of different diets to verify that the caprellids were able to feed on three different food sources: detritus, Artemia and phytoplankton. With different experiments, the team evaluated the lipid composition of caprellids and their nutritional value for use as a resource for aquaculture in the framework of the project “Caprellid invaders of the Andalusian coast. Applications in aquaculture,” funded by the Ministry of Economy and Knowledge of the Andalusian.

Specifically, researchers tested two of the most abundant species in the Strait of Gibraltar: Caprella balances and Caprella Scaura. The first is an indigenous species and the second is an invasive species found in high densities. After the experimental characterization, experts concluded that the nutritional value of caprellids fed with detritus is suitable. This advantage makes them a viable option for the aquaculture industry.

The next step facing researchers is to estimate the amount of detritus that caprellids could recycle as active agents of bioremediation. Another future project is centered on the large-scale cultivation of these tiny crustaceans.