The potential use of Gracilaria sp. meal in diets for juvenile Penaeus monodon Fabricius

Five diets were formulated to investigate the effects of substituting wheat flour and soybean meal with various inclusion levels of seaweed (Gracilaria sp.) meal on the diet stability, performance and carcass composition of juvenile shrimp Penaeus monodon Fabricius. Gracilaria meal inclusion levels from 5% to 30% were tested against a control (0% seaweed) in isonitrogenous, isoenergetic diets fed for 60 days to quadruplicate groups of shrimp held in laboratory brackishwater recirculation system. Diets containing Gracilaria meal at up to 10% inclusion had no significant effects on diet water stability (after 12 h), shrimp performance or carcass composition compared with the control diet lacking seaweed. Diets containing 0-15%Gracilaria meal remained >88% water stable after 12 h, shrimp specific growth rates (SGRs) were 7.9-8.0% wet body weight day^-1. survival was 48-56%, food conversion ratios were 3.1-3.5, and final carcass lipid levels were 6.8-7.5%. The 30% inclusion levels of Gracilaria meal resulted in a significant deterioration in diet water stability (86% after 12 h), shrimp growth (SGR 7.3% wet body weight day^-1) and carcass lipid level (4.1%). It is suggested that with the low cost and increasing availability of Gracilaria, it may be a suitable ingredient for low-level inclusion into formulated diets for shrimp culture. The possibility of using seaweed meals for this purpose is discussed with regard to diversifying the market for cultured seaweeds and enhancing the integration of seaweed culture into coastal aquaculture systems.     

Nutrient removal efficiency of Hydropuntia cornea in an integrated closed recirculation system with pink shrimp Farfantepenaeus brasiliensis

In this study, we have tested the effect of seaweed stocking density in an experimental seaweed biofilter using the economically important red seaweed Hydropuntia cornea integrated with the cultivation of the pink shrimp Farfantepenaeus brasiliensis. Nutrient removal efficiency was evaluated in relation to seaweed stocking density (2.5, 4, 6 and 8 g fw L^?1). Total ammonia nitrogen (TAN) was the main nitrogen source excreted by F. brasiliensis, with concentrations ranging from 41.6 to 65 μM of NH₄⁺‐N. H. cornea specific growth rates ranged from 0.8 ± 0.2 to 1.4 ± 0.5% day^?1 with lowest growth rates at higher seaweed stocking density (8 g fw L^?1). Nutrient removal was positively correlated with the cultivation densities in the system. TAN removal efficiency increased from 61 to 88.5% with increasing seaweed stocking density. Changes in the chemical composition of the seaweed were analysed and correlated with nutrient enrichment from shrimp effluent. The red seaweed H. cornea can be cultured and used to remove nutrients from shrimp effluents in an integrated multi‐trophic aquaculture system applied to a closed recirculation system. Recirculation through seaweed biofilters in land‐based intensive aquaculture farms can also be a tool to increase recirculation practices and establish full recirculation aquaculture systems (RAS) with all their known associated benefits.     

Co‐culture of sea cucumber Holothuria scabra and red seaweed Kappaphycus striatum

Commercially valuable sea cucumbers are potential co‐culture species in tropical lagoon environments, where they may be integrated into established aquaculture areas used for seaweed farming. In the current study, wild‐caught juvenile sea cucumbers, Holothuria scabra, and red seaweed Kappaphycus striatum were co‐cultured on Zanzibar, United Republic of Tanzania. Sea cucumbers (97 g ± 31 SD, n = 52) were cultured in mesh enclosures at initial cage stocking densities of 124 ± 21 SD and 218 ± 16 SD g m^?2 under seaweed culture lines. Over 83 days, individual growth rate (1.6 g d^?1 ± 0.2 SD) of sea cucumbers at low stocking density was significantly higher (χ² = 8.292, d.f. = 1, P = 0.004) than at high‐stocking density (0.9 g d^?1 ± 0.1 SD). Seaweed individual growth rates [6.27 (±0.3 SE) g d^?1] were highest in co‐culture with sea cucumber at low density but did not differ significantly from high sea cucumber density or seaweed monoculture treatments (χ² = 3.0885, d.f. = 2, P = 0.2135). Seaweed growth varied significantly (χ² = 35.6, d.f. = 2, P < 0.0001) with sampling period, with the final sampling period resulting in the highest growth rate. Growth performance for seaweed and sea cucumbers (χ² = 3.089, d.f. = 2, P = 0.21 and χ² = 0.08, d.f. = 1, P = 0.777 respectively), did not differ significantly between monoculture and co‐culture treatments, yet growth in co‐culture was comparable with that reported for existing commercial monoculture. Results indicate H. scabra is a highly viable candidate species for lagoon co‐culture with seaweed. Co‐culture offers a more efficient use of limited coastal space over monoculture and is recommended as a potential coastal livelihood option for lagoon farmers in tropical regions.     

Experimental evaluation of a composted seaweed extract as microalgal culture media

An organic culture media based on a composted liquid seaweed extract was developed and tested for growth of Chaetoceros muelleri. The extract was evaluated at two concentrations and then compared with two commercial media: Walne and agricultural fertilizer (AF). The concentrations of nitrogen and phosphorous differed between the two commercial media and the seaweed extract; however, growth of Chaetoceros muelleri was similar. The successful culture of Chaetoceros muelleri in composted liquid seaweed extract suggests the feasibility of and potential use for this natural, organic fertilizer in aquaculture. The seaweed extract is simple to obtain and inexpensive.     

Effect of dietary seaweed supplementation on growth performance,antioxidant and immune responses in European seabass (Dicentrarchus labrax) subjected to rearing temperature and salinity oscillations

The current study evaluated the effects of dietary seaweed supplementation in European seabass juveniles (Dicentrarchus labrax) subjected to rearing temperature and salinity oscillations, simulating natural variations in pond aquaculture conditions. Two experimental diets where formulated: a control diet (CTRL) with no supplementation and one supplemented with 7.5% seaweed mix (SW 2.5% Fucus sp., 2.5% Gracilaria sp. and 2.5% Ulva sp.). Seabass from both dietary groups (40.7 g initial body weight) was subjected to either combined salinity and temperature oscillations, or to fixed conditions. Growth performance, innate immune, and oxidative stress responses were evaluated. Results showed that seaweed supplementation had no significant effect on the analyzed parameters. However, environmental oscillations revealed significant effects on growth performance and oxidative stress response. Fish subjected to salinity and temperature oscillations had a significantly lower weight gain and daily growth index than those subjected to fixed conditions, regardless of dietary treatment. Total glutathione, oxidized glutathione, and catalase increased in fish subjected to oscillatory conditions. Lysozyme and peroxidase were not influenced by either diet or environmental conditions. In conclusion, this particular dietary seaweed mix supplementation did not mitigate the negative effects of environmental oscillations on growth performance and innate immune responses in European seabass.

     

汕头南澳龙须菜规模栽培对水质和浮游植物的影响

为研究大型海藻龙须菜(Gracilaria lemaneiformis)规模栽培对水质和浮游植物的影响,于2016年3―6月在南澳深澳湾选择龙须菜栽培区(G)、鱼类养殖区(F)和对照区(C)3个采样区域,每个采样区域3个采样点,进行每月1次的采样调查。对海水温度(WT)、盐度(salinity)、pH、溶氧(DO)、总氮(TN)、总磷(TP)、无机氮(DIN)、无机磷(DIP)、叶绿素a(Chl a)和浮游植物密度进行测试分析。结果表明:(1)在龙须菜栽培期和收获期(3―5月),龙须菜栽培区的pH和DO均显著高于其余区域(P<0.05),收获后各区域无显著性差异(P>0.05);(2)在龙须菜栽培期(3―4月),栽培区的TN、TP、DIN和DIP含量均显著低于对照区和鱼类养殖区(P<0.05);(3)龙须菜栽培期间和收获期(3―5月)栽培区浮游植物密度显著低于其他区域(P<0.05),龙须菜收获后(6月),3个采样区域浮游植物的密度大幅上升;(4)2016年南澳海域共收获龙须菜49729 t,据估算,龙须菜规模栽培从海水中移除了2212 t N、174 t P和13300 t C,至少释放了34700tO_2。研究表明,龙须菜规模栽培能有效去除N、P营养盐,防治海洋富营养化;提高栽培区域的pH和DO,有利于防治海洋酸化和低氧问题;降低浮游植物密度,抑制有害藻华的发生。     

Growth‐promoting bacteria for the green seaweed Ulva clathrata

Seaweed production represents one of the rising activities in the aquaculture industry. This study explores the impact of bacteria associated with the growth of Ulva clathrata, a promising alga in the field of food and bioremediation. Fifty‐six bacteria isolated from four seaweed (Caulerpa sp., Gracilaria sp., Ulva lactuca and U. clathrata) were tested to evaluate their effect on U. clathrata growth. Eight of them showed a significant growth‐promoting effect (p < .05). Isolates Ul‐11 and Ul‐12 from U. lactuca induced an increase of 73 and 81% of growth respectively. They were classified as Reugeria sp. and Alteromonas sp. based on 16S DNA sequencing (>95.0% sequence identity). Multiple combinations of the growth‐promoting bacteria were also tested on U. clathrata, and the best result was achieved by combining Ca‐3/Uc‐18/Ul‐12 isolates with a significant increase in seaweed growth of up to 76%; however, no synergistic effect was observed compared to Ul‐12 alone. Scanning electron microscopy revealed no alteration in the cell wall of U. clathrata when inoculated with selected bacteria, showing an average increase of bacterial density on U. clathrata.     

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

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.     

Growth and mortality of the king scallop grown in suspended culture in Malaga, Southern Spain

Growth and mortality of the king scallop, Pecten maximus, werecompared when grown in cages and by ear hanging in suspended culturein Fuengirola, Malaga, in southern Spain. Seed (juveniles) used in theexperiment was collected in September 1997 that had settled on collectorsin April-June, of that year. Culture in suspended cages began in January1998 when the seed measured 42.7 (3.3) mm shell height and ended inFebruary 1999. Significantly faster growth was found at a minimum culturedensity (16 scallops/cage) than at two other densities (24 and 36scallops/cage). Depth (1, 5 and 10 m from the bottom) influenced growth,poorest growth occurred closest to the bottom. Under optimum growingconditions, 16 scallops/cage suspended 10 m from the bottom, scallops grewto 10 cm shell length (legal size) by February 1999.In ear hanging culture, ropes were moored in April (51.3 (4.5) mm),June (58.2 (4.5) mm) and November 1998 (64.3 (4.9) mm).Initially, rapid shell growth was observed in all three cultures.Subsequently, the shells became covered with barnacles, Balanus sp.,that possibly caused total mortality of the April culture and led to highmortalities in the two other cultures.     

Productive performance of brown mussels Perna perna (Linnaeus, 1758) cultivated on ropes at low densities in Caraguatatuba,Brazil

In Brazil, mussel seed are not a plentiful natural resource, and so the efficient use of seeds by reducing stocking densities should be considered. There are very few studies addressing the relationship between seeding density and growth of mussels in tropical conditions. This work aimed to determine the influence of low seeding densities on the productive performance of Perna perna (Linnaeus) mussels cultivated on ropes in Caraguatatuba, Brazil. In October 2014, 12 ropes, one metre in length each, were seeded at the densities of 200, 300 and 400 mussels/m (four ropes for each density) and suspended on a long line. After 226 days of growing, mussels were harvested and their performance at each density was evaluated in terms of mean weight and length, production, culture efficiency, condition index, survival, amount of recruited seed, amount of fouling on the ropes and morphometric relationships. We observed no significant differences (p > .05) for these indicators among the densities tested, except for mussel biomass, which was significantly higher (p < .05) at the greater densities. A partial budget analysis showed that the density of 400 m^?1 showed better profitability and should be recommended, even in case of seed shortage.     

Water quality,phytoplankton composition and growth of Litopenaeus vannamei (Boone) in an integrated biofloc system with Gracilaria birdiae (Greville) and Gracilaria domingensis (Kützing)

A 28-day indoor trial was conducted to evaluate the water quality, phytoplankton composition and growth of Litopenaeus vannamei in an integrated biofloc system with Gracilaria birdiae and Gracilaria domingensis. The experimental design was completely randomized with three treatments: control (shrimp monoculture); SB (shrimp and G. birdiae) and SD (shrimp and G. domingensis), all with three replicates. Random sampling was done (6 % of total population per experimental unit) to confirm white spot syndrome Virus (WSSV) infection using nested-PCR analysis due to suspicion of presence of the virus in the experiment (treatment and control groups). Shrimp L. vannamei (2.63 ± 0.10 g) were stocked in experimental tanks at a density of 425 shrimp m^?3, and the Gracilaria was stocked at a biomass of 2.0 kg m^?3. Shrimp mortality began in both the experimental and control groups at 10 days of culture. The integrated biofloc system (shrimp and seaweed) increased settleable solids (by 26–52 %); final weight (by 6–21 %); weekly growth (by 17–43 %); weight gain (by 17–43 %); specific growth rate (by 16–36 %); and yield (by 5–7 %) and decreased feed conversion ratio (by 21–28 %) and Cyanobacteria density about 16 % as compared to the control (shrimp monoculture). The use of red seaweed Gracilaria in an integrated biofloc system can enhance shrimp growth and reduce Cyanobacteria density in the presence of WSSV.     

Development of a Model to Simulate Nitrogen Dynamics in an Integrated Shrimp–Macroalgae Culture System with Zero Water Exchange

The effluents of traditional shrimp monoculture cause pollution and promote eutrophication and hypernutrification of the receiving coastal ecosystems. Integrated aquaculture and a recirculating aquaculture system (RAS) have been proposed as an alternative to address these problems. In this study, we developed a dynamic model to simulate the concentration of total ammonia nitrogen (TAN), nitrite, and nitrate in an integrated culture of whiteleg shrimp, Litopenaeus vannamei, and seaweed, Gracilaria vermiculophylla, in a recirculating and zero water exchange system, and the effect of nitrifying and heterotrophic bacteria was also included. The experiments demonstrated that a dynamic model can explain the concentrations of dissolved inorganic nitrogen and variations in these concentrations over time in the integrated culture. The results also suggest that nitrifying and heterotrophic bacteria play an important role in the transformation of dissolved nitrogenous compounds; therefore, these bacteria should be considered within the dynamics of nitrogen in integrated systems with low water exchange.     

Field assessment of two methods for planting the agar-containing seaweed,Gracilaria, in Northern Chile

Two simple methods for mass field cultivation of Gracilaria in Northern Chile were assessed. Thalli fragments were tied either to small rocks or to sand-filled polyethylene tubes to form 120-m² stands, on a shallow (3–5 m depth) sandy marine bottom with an underlying sandstone substratum. Short-term (6 months) thalli growth and resistance to wave action were evaluated on both stands, and the behaviour of these artificial beds was compared with that of a small undisturbed natural Gracilaria bed (ca. 3 ha) near the experimental area. A pilot artificial bed of 2500 m² was also established beside the experimental stands, for long-term assessment of the method using sand-filled tubes.Sand displacement and surfacing of the sandstone substratum due to moderate water turbulence caused a continual decline of the natural bed, but had no apparent effect on the artificial beds. Biomass increment in these plantations was 2600–2800% (fresh weight) in a 6-month period. Intense water turbulence at the end of this period had a significantly less destructive effect on the experimental and pilot beds planted with sand-filled tubes.Three years after the establishment of the pilot bed, natural recolonization had increased its area four-fold, in spite of intense and uncontrolled harvesting during the last year. This behaviour was attributed to the generation of a dense underground thalli system in this bed, due to the strong attachment provided by the sand-filled tubes. At this time (July 1985) underground biomass doubled the standing stock.Under the conditions tested in this study, the sand-filled tube method was the most feasible from a technological point of view.     

Effect of inland saline water ionic profiles on growth,chemical composition and agar characteristics of <Emphasis Type="Italic">Gracilaria cliftonii</Emphasis> (Withell,Miller and Kraft 1994) under laboratory conditions

Increase in salinity of inland water sources is adversely affecting aquatic and terrestrial ecosystems around the world including Australia. Inland saline water (ISW) with similar ionic profile to ocean water has potential for culturing marine species. Gracilaria species are commercially important as they are a source of agar. One of the native species Gracilaria cliftonii has been reported for high agar yield of 52%dw. The aim of this research was to investigate the feasibility of culturing G. cliftonii in different ionic profiles of ISW under laboratory conditions. The growth rate of G. cliftonii under different ionic profiles ranged from 0.9 to 2.5 %day⁻¹. Gracilaria cliftonii carbohydrate content decreased while protein content increased in culture conditions when compared to natural populations. Agar yield, gel strength and melting point decreased while gelling temperature and sulphate content increased in culture conditions when compared to natural populations. Strong correlation (R ² > 0.8, P < 0.05) was observed between K⁺, Na⁺, Ca²⁺, and Mg²⁺ content in tissue and water indicating ionic regulation by G. cliftonii. This research provides basic information and presents supportive arguments for G. cliftonii as a potential species for inland saline water aquaculture.     

Economic aspects of Gracilaria culture in Taiwan

The cultivation of Gracilaria is described, costs and returns of the operation are analyzed, and the market demand is evaluated. Gracilaria culture is a labor-intensive operation. However, annual productivity and profit are high. The increasing demand and rising price of raw Gracilaria, and agar derived from it, are likely to encourage Gracilaria cultivation not only in Taiwan but also in other developing countries with sites suitable for its cultivation.     

First attempt to cultivate the carrageenan-producing seaweed Chondracanthus chamissoi (C. Agardh) Kützing (Rhodophyta; Gigartinales) in Northern Chile

Chondracanthus chamissoi is an important source of carrageenan in Chile. Presently, all the production is harvested from wild populations. This study reports the first attempt to cultivate C. chamissoi. Experiments were conducted with female gametophytic and sporophytic thalli by inserting them among braids of a 7 mm polypropylene rope. Inoculated ropes were placed at 1, 3 and 5 m depths in two sheltered bays in northern Chile. The fronds adapted well to cultivation and grew at all the depths tested, although the greatest increase in biomass was observed at 1 m depth. On a yearly cycle, higher biomass increases were observed in autumn and winter months compared with the spring and summer. We believe that by adapting the cultivation methodology, this species could be cultivated year round.     

Aquaculture potential of the basket cockle (Clinocardium nuttallii). Part 1: effects of stocking density on first year grow‐out performance in intertidal and off‐bottom suspended culture

The basket cockle (Clinocardium nuttallii) is a candidate species for aquaculture in the northeast Pacific. The aim of the current research was to assess the feasibility of C. nuttallii grow‐out, with an emphasis on growth performance and qualities affecting product marketability. In this article, we investigated the combined effects of culture mode (intertidal and off‐bottom suspended culture) and initial stocking density (1500, 3000, 10 500 and 21 000 ind m^?2) on C. nuttallii survival and growth during the first year of grow‐out (May through October). In intertidal culture, cockles exhibited low survival and poor growth rates. In suspended culture, survival was consistently high (>96%) at all stocking densities tested; growth and condition parameters had the highest values at 1500 and 3000 ind m^?2. The edible portion (meat yield) exceeded 40% of the whole wet weight at all stocking densities, occurrences of fouled and deformed cockles were <1% and no commensal species were observed. Depending on the minimum harvestable size and stocking density chosen, harvestable proportions constituted from 1.1% to 15.2% by October of the first grow‐out year in the suspended system. The effects of stocking density and depth on second year grow‐out performance of C. nuttallii are reported in a companion paper (Dunham et al. in this issue).     

Grow-out culture of tropical abalone, Haliotis asinina (Linnaeus) in suspended mesh cages with different shelter surface areas

Thisstudy investigated the effects of shelter surface area (SSA) on the feeding,growth and survival of the donkey-ear abalone, Haliotisasinina reared in mesh cages (0.38×0.38×0.28m) suspended in flow-through tanks (water volume = 6m³). Cages had sections of polyvinylchloride (PVC) thatprovided shelters with surface area of 0.22 m², 0.44m² and 0.66 m².Hatchery-produced abalone with initial shell length of 32 ± 1mm and wet weight of 7.5 g were stocked at 50individuals cage^–1 that corresponded to stocking densities ofca. 227, 113 and 75 abalone m^–2 of SSA. The ratios of sheltersurface area to cage volume (SSA:CV) were 5.5, 11 and 16.5. Abalones wereprovided an excess red seaweed Gracilariopsis bailinae(= Gracilaria heteroclada) at weekly intervals overa 270-day culture period. Feeding rates (18–20% of wet weight), foodconversion ratio (26–27) and percent survival (88–92%) did notdiffer significantly among treatments (p > 0.05). Body size at harvest rangedfrom 56 to 59 mm SL and 52 to 57 g wet body weightwith significant differences between abalone reared at SSA 0.22m² and 0.66 m² (p < 0.05).Abalone reared in cages with 0.66 m² SSA grewsignificantly faster at average daily growth rates of 132 m and188 mg day^–1. Stocking densities of 75–113m^–2 SSA in mesh cages suspended in flow-throughtanks resulted in better growth of abalone fed red seaweed.     

Study on an integrated eco‐aquaculture system for rearing the yellow seahorse,Hippocampus kuda Bleeker

Seahorse aquaculture is challenged by insufficient feeding supply and lack of biological and nutritional knowledge, resulting in low survival rate and poor economical profitability. We report here an integrated eco‐aquaculture system in which the yellow seahorse and its natural prey were co‐cultured with fertilized water and seaweed in cement ponds. In the first stage, urea (10 g m^?3) and chicken manure (50 g m^?3) were used to fertilize the cultured water, 5–7 days later, rotifer and micro‐crustaceans were flourishing. Then, seahorse juveniles were stocked at 200 ind m^?3. After 2 weeks, seaweed Gracilaria lichevoides was transplanted into the ponds to regulate water quality, light and to provide holdfast attachment for seahorses. The optimal density of G. lichevoides was controlled between 0.5 and 2 kg m^?3. The introduction of seaweed provides the habitat for natural food of seahorse. Within the cluster of the seaweed, small crustacean density was over 450 individuals per 100 g of fresh weight. Initial size of seahorse juvenile was 1.03 ± 0.091 cm, After the 146‐day rearing period, seahorse survival rates were 70.8%, 57.7% and 42.5%, and body standard lengths were 11.33 cm, 10.84 cm and 10.04 cm in the integrated eco‐aquaculture system (GFA) and in monoculture systems of FA (fertilized + feeding) and BA (only feeding) respectively. This system incorporated traditional Chinese aquaculture technique in which feedings nature food organisms were cultivated by fertilization and ecological regulation. Results from these preliminary experiments suggest that the integrated system could be technically feasible, suitable and exemplary.     

Effects of water depth on survival and growth of <Emphasis Type="Italic">Argopecten purpuratus</Emphasis> (Lamarck, 1819) spat in northern Chile

Collection and suspended culture of Argopecten purpuratus spat in Japanese-type collectors was undertaken in the Rinconada Marine Reserve (Antofagasta, Chile) to determine growth variations between surface and bottom waters. Scallop spat was collected at 16-m depth and grown at 1- and 16-m depths. An initial settlement of ca. 13,000 post-larvae per bottom collector (2 cohorts) was observed on 3 February 2001. Two new cohorts settled in bottom collectors on 3 March, while no spat settlement occurred in surface collectors. The four cohorts exhibited substantial and different mortality rates over the study period, depending on the cohort and on-growing depth. The first and second cohorts exhibited mortality rates of 80.3 and 53.1% in bottom collectors, respectively, versus 29 and 43.6% in surface structures. The third and fourth cohorts exhibited mortality rates of 21.4 and 59.7% in bottom collectors, respectively. Mean shell height of scallop spat after 88 days of culture was 6.46 mm for the first cohort and 4.37 mm for the second cohort in bottom collectors, versus 10.33 and 7.31 mm in surface collectors, respectively. Mean post-larval growth rate in bottom collectors (86 μm day⁻¹) was significantly lower than growth rate in surface collectors (146 μm day⁻¹). Factors explaining the depth-related mortality and growth rates are discussed to improve scallop culture in the Reserve. It was concluded from the results that culture improvement in Antofagasta Bay would require collecting spat in bottom waters and raising it near the surface during initial cultivation stages.