Carl Christina, de Nys Rocky, Paul Nicholas A
MACRO - the Centre for Macroalgal Resources and Biotechnology, School of Marine and Tropical Biology, James Cook University, Townsville, Queensland, Australia.
PLoS One. 2014 Jun 4;9(6):e98700. doi: 10.1371/journal.pone.0098700. eCollection 2014.
Filamentous species of Ulva are ideal for cultivation because they are robust with high growth rates and maintained across a broad range of environments. Temperate species of filamentous Ulva are commercially cultivated on nets which can be artificially 'seeded' under controlled conditions allowing for a high level of control over seeding density and consequently biomass production. This study quantified for the first time the seeding and culture cycle of a tropical species of filamentous Ulva (Ulva sp. 3) and identified seeding density and nursery period as key factors affecting growth and biomass yield. A seeding density of 621,000 swarmers m(-1) rope in combination with a nursery period of five days resulted in the highest growth rate and correspondingly the highest biomass yield. A nursery period of five days was optimal with up to six times the biomass yield compared to ropes under either shorter or longer nursery periods. These combined parameters of seeding density and nursery period resulted in a specific growth rate of more than 65% day(-1) between 7 and 10 days of outdoor cultivation post-nursery. This was followed by a decrease in growth through to 25 days. This study also demonstrated that the timing of harvest is critical as the maximum biomass yield of 23.0 ± 8.8 g dry weight m(-1) (228.7 ± 115.4 g fresh weight m(-1)) was achieved after 13 days of outdoor cultivation whereas biomass degraded to 15.5 ± 7.3 g dry weight m(-1) (120.2 ± 71.8 g fresh weight m(-1)) over a longer outdoor cultivation period of 25 days. Artificially seeded ropes of Ulva with high biomass yields over short culture cycles may therefore be an alternative to unattached cultivation in integrated pond-based aquaculture systems.
石莼属的丝状物种适合养殖，因为它们生命力强、生长速度快，且能在多种环境中生长。温带丝状石莼物种在网具上进行商业养殖，可在可控条件下人工“播种”，从而能高度控制播种密度，进而控制生物量产量。本研究首次对热带丝状石莼物种（石莼3号）的播种和养殖周期进行了量化，并确定播种密度和育苗期是影响生长和生物量产量的关键因素。每米绳索621,000个游动孢子的播种密度与五天的育苗期相结合，可实现最高生长速度，相应地生物量产量也最高。五天的育苗期是最佳选择，与育苗期较短或较长的绳索相比，生物量产量高达六倍。这些播种密度和育苗期的组合参数，使得育苗后室外养殖7至10天期间的特定生长率超过65%/天。此后生长速度下降，直至25天。本研究还表明，收获时机至关重要，因为室外养殖13天后可实现最大生物量产量23.0±8.8克干重/平方米（228.7±115.4克鲜重/平方米），而在25天的较长室外养殖期后，生物量降解至15.5±7.3克干重/平方米（120.2±71.8克鲜重/平方米）。因此，在基于池塘的综合水产养殖系统中，短养殖周期内具有高生物量产量的人工播种石莼绳索，可能是无附着养殖的一种替代方案。
