Aquaculture

A B S T R A C T
The long spined sea urchin Diadema antillarum was an abundant grazer on Caribbean coral reefs, until
1983–1984, when densities were reduced by ~98% during a region wide die-off. Since then, there has been very
little natural recovery of the species and interest is growing in applying aquaculture as a tool for population
enhancement. In this study we optimized a new shaker bottle cultivation method for D. antillarum. The method
was tested in a series of experiments by culturing D. antillarum from egg to juvenile in the Netherlands as well as
the USA. Larvae were cultured in standard 1-L glass reagent bottles, suspended by gentle constant movement on
an orbital shaking table and fed with either the microalgae Rhodomonas lens or Rhodomonas salina. Effects on
larval growth and survival were evaluated for different microalgal feeding concentrations, larval densities, and
culture temperatures. Larval density and growth were measured twice a week over a period of up to 56 days.
Larvae grew significantly faster on a higher feeding concentration up to 90,000 Rhodomonas sp. cells mL

Shoot organization in seagrasses varies from the unspecialized condition of Enhalus and Posidonia to the highly differentiated shoot systems of plants like Halophila, Thalassodendron and Thalassia. In the former type proliferation of vegetative meristems seems to be an unordered process, whereas in the latter type proliferation can be very ordered. In some examples, e.g. Syringodium, proliferation of rhizomes is not regularized in shoot organization but is largely a consequence of perturbation by the environment. Since production of new organs and proliferation of indeterminate shoot systems is dependent entirely on continually active meristems, with either a limited tendency to form resting meristems or often no such ability at all, seagrasses show a high degree of meristem dependency.