Experimental investigations for the mariculture ofGracilaria in Saldanha bay, South Africa

Anderson, R. J.; Levitt, G. J.; Share, A.

doi:10.1007/bf02178587

Cited by 31 publications

(11 citation statements)

References 17 publications

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“…In general, RGR obtained were low compared to other studies (Dawes 1995). Nevertheless, the RGR maximum value recorded in July was similar to experiments with high productivity elsewhere (Anderson et al 1996;Troell et al 1997;Nelson et al 2001). It would appear that July is a favourable period for good growth of Gracilaria in this estuary.…”

Section: Discussionsupporting

confidence: 74%

“…Reported biomass values of Gracilaria from the estuary are low compared to studies in other countries (Anderson et al 1996;Anderson et al 1999;Buschmann et al 2001). Periodic fluctuations in the environmental parameters may explain the lower production observed for this species, considering that the macroalgae used in cultivation experiments were collected in sea.…”

Section: Discussioncontrasting

confidence: 49%

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Some Aspects of the Growth of Gracilaria birdiae (Gracilariales, Rhodophyta) in an Estuary in Northeast Brazil

2006

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The agarophyte Gracilaria birdiae Plastino & Oliveira was cultivated under field conditions in an estuary over a 6-month period. Biomass production varied significantly (p<0.01) and ranged from 900.0 to 3537.0 g m )2 with a mean of 2124.4±1004.36 g m )2 over the cultivation period. The epiphyte-biomass varied from 64.7 to 313 g m )2 , with maximum values observed in July. Relative growth rate (RGR) of G. birdiae varying from )0.59 to 4.67% day )1 , with a maximum mean observed in July. Correlation analysis showed that RGR was positively correlated with epiphyte-biomass (R-Pearson=0.69; p< 0.01) and negatively correlated with salinity (R-Pearson=)0.41; p<0.05). These correlations were used in a mathematical regression model to estimate the growth of Gracilaria in an estuary. The regression model explained 61% of RGR variability demonstrating that growth rates of Gracilaria were directly related to the variables salinity and epiphytes. The model was developed to help to predict production at a cultivation site in order to evaluate its suitability for Gracilaria cultivation.

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Section: Discussionsupporting

confidence: 74%

Section: Discussioncontrasting

confidence: 49%

Some Aspects of the Growth of Gracilaria birdiae (Gracilariales, Rhodophyta) in an Estuary in Northeast Brazil

2006

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“…Ryther et al 1984). There was some initial local research growing Gracilaria on rope rafts in the sea both in neighbouring Namibia (Dawes 1995;Molloy and Bolton 1996) and in South Africa (Anderson et al 1996Wakibia et al 2001). Thus, when initial studies to grow seaweeds for feed began, at Marine Growers farm in Port Elizabeth, Gracilaria was an obvious candidate.…”

Section: Strengthsmentioning

confidence: 95%

Growing Ulva (Chlorophyta) in integrated systems as a commercial crop for abalone feed in South Africa: a SWOT analysis

et al. 2008

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Over 1,000t fresh weight of Ulva was cultivated on South African abalone farms in 2007, primarily for feed, but in one case to allow partial re-circulation by nutrient removal. The potential of this new commercial crop is analysed. Material is collected from natural free-floating populations and at least four species are commonly grown, with different ecophysiological characteristics. A brown epiphyte, Myrionema strangulans, causes a disease of the Ulva, which is currently managed by farmers by restocking. The main potential threat is that some farmers are wary of integrated systems, fearing they may promote disease in abalone, although Ulva has been grown in abalone effluent and fed back to the abalone on one farm for 6 years without adverse effects. Opportunities exist for the expansion of Ulva cultivation via further spread of the abalone industry, the inclusion of seaweed raceways in proposed fish-farming activities, or the potential for the inclusion of high quality cultivated Ulva as a constituent in aquafeed. A conservative estimate of production over a full year from these raceway systems was 26.1 g dw m −2 day −1 (2006) and 19.7 g dw m −2 day −1 (2007), similar to maximum figures for total annual microalgal biomass production in outdoor systems.

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“…Experimental cultivation studies in Saldanha Bay (Anderson et al 1996) and St Helena Bay (Wakibia et al 2001) have shown promise, with the latter site yielding higher and seasonally consistent growth rates (Anderson et al 2003). While occasional H 2 S events could destroy cultivated gracilarioids in St Helena Bay, we believe that such an effect on a crop could be avoided.…”

Section: Discussionmentioning

confidence: 96%

The gracilarioids in South Africa: long-term monitoring of a declining resource

Rothman¹,

Anderson

Boothroyd³

et al. 2008

J Appl Phycol

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In South Africa, gracilarioid red algae have been collected as wash-up to be dried and sold for agar extraction for at least 50 years. Despite much research, there is currently no commercial mariculture of the algae locally although this has been carried out in neighboring Namibia for a number of years. The industry is traditionally confined to Saldanha Bay on the west coast, although small wash-ups of Gracilariopsis longissima have been collected in nearby St Helena Bay. In Saldanha Bay, wash-ups of Gracilaria. gracilis have been very sporadic over the last few decades, with human alteration of the bay configuration possibly responsible for an initial major decline in 1974. This unpredictability in the amounts of wash-up has made the industry unstable and increasingly unprofitable. We compiled the results of previous surveys (some unpublished) of gracilariod populations in St Helena Bay and the Saldanha-Langebaan sytem, and re-surveyed these populations to examine long-term fluctuations. In Saldanha Bay and Langebaan Lagoon, standing stock of G. gracilis was estimated at 538 tons fresh weight and 71 tons fresh weight respectively. Less than 4 tons of gracilarioids are estimated to remain in St Helena Bay. We discuss the fluctuations in biomass and distribution of these South African gracilarioid populations.

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Experimental investigations for the mariculture ofGracilaria in Saldanha bay, South Africa

Cited by 31 publications

References 17 publications

Some Aspects of the Growth of Gracilaria birdiae (Gracilariales, Rhodophyta) in an Estuary in Northeast Brazil

Some Aspects of the Growth of Gracilaria birdiae (Gracilariales, Rhodophyta) in an Estuary in Northeast Brazil

Growing Ulva (Chlorophyta) in integrated systems as a commercial crop for abalone feed in South Africa: a SWOT analysis

The gracilarioids in South Africa: long-term monitoring of a declining resource

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