The effect of predator/prey density and water dynamics on feed intake and growth in spiny lobster larvae (Jasus edwardsii)

Abstract

Consumption of Artemia by phyllosoma of the spiny lobster Jasus edwardsii was examined under static and turbulent conditions. Phyllosoma larvae were stocked at two densities (2 or 4 phyllosoma container -1 ; 2P or 4P) and fed juvenile Artemia (1.6mm total length) at two feed rates (1.5 or 0.75 Artemia ml -1 ; 1.5A or 0.75A) in 50 ml of seawater. This provided a combination of 4 treatments (2P/1.5A, 2P/0.75A, 4P/1.5A, 4P/0.75A). Daily intake of Artemia by phyllosoma was monitored and assessed relative to moult size and intermoult duration at differing predator-prey densities. Phyllosoma numbers were held constant; in the event of mortality, animals were replaced with others from the same cohort cultured under similar conditions. Phyllosoma endogenous reserves at hatch combined with the lowest ration of 0.75 A was sufficient to ensure normal growth and intermoult duration until Stage II. When phyllosoma were fed for an extended period (several moults), low ration and high phyllosoma density resulted in smaller size and extended intermoult duration. Fluctuations in the feeding pattern of phyllosoma were evident between treatments during the experiment. Phyllosoma with access to more Artemia consumed more, and consumption was reduced prior to a moult, even during early stages of development. The second phase of the study examined the intake of 1.7 mm juvenile Artemia by phyllosoma and their response to flow-induced turbulence with a combination of two water exchange rates (2.5 or 5 times h -1 ) and two inlet positions (2 cm above the water surface or 0.5 cm above the culture vessel bottom and parallel to it). Larvae exposed to slow flow were larger and had a shorter intermoult duration associated with an increased ability to capture and consume more Artemia. Similar numbers of Artemia were consumed during the intermoult in high flow treatments compared to the low flow, albeit over a longer duration. Phyllosoma development between moults required less Artemia to be consumed under static conditions.

Relative contribution ofArtemiaand mussel as food for cultured middle‐stagePanulirus japonicusphyllosomata as determined by stable nitrogen isotope analysis

“…The relationship between the contribution of each diet and the developmental stage of larvae should be examined in more detail. Moreover, the relative contribution of Artemia may change depending on the culture system, such as tank design, water current and lighting, used because it affects the distribution of Artemia in a culture tank (Moss et al 1999;Smith et al 2007). …”

Use of microspheres, fresh and microbound diets to ascertain dietary path, component size, and digestive gland functioning in phyllosoma of the spiny lobsterPanulirus ornatus

“…In the last two decades, research into spiny lobster propagation has been conducted primarily in Japan, India, New Zealand, andAustralia (Vijayakumaran& Radhakrishnan 1986;illingworth et al 1997;Phleger et al 2001;Ritar et al 2006;Smith et al 2007). Although research effort has focused on general husbandry and culture issues, there are other facets of phyllosoma research impeding the transition to commercial success.…”