Juvenile Abalone Research Articles

해상가두리 및 육상수조 중간양성 방식에 따른 북방전복, Haliotis discus hannai 치패의 성장 및 생존율

본 연구는 해상가두리와 육상수조의 다양한 중간양성 방법에 대한 성장 및 생존율을 조사하여 육상수조에서의 전복치패 양성의 효율성 증가와 생산성향상을 유도하고자 실시하였다. 해상가두리 (net cage culture, NCC) 실험은 육상수조 사육은 2013년 6월부터 2014년 4월까지 10개월 (300일) 동안 실시하였고, 실험 전복은 2012년에 종묘생산 된 양성 1년생 (각장 평균 22.74-23.67 mm) 을 사용하였다. 육상수조 실험구 설정은 바닥식 양성 (floor culture, FC), 그물 바닥식 양성(net floor culture, NFC), 이중 쉘터 양성 (double shelter culture, DSC) 그리고 육상 가두리 양성 (indoor net cage culture, INCC) 을 각각 2반복구로 설정하여, 수조 당 10,000 마리를 수용하였다. 해상가두리의 월별 각장과 성장률(absolute growth rate of shell length, <TEX>$AGR_{SL}$</TEX>) 은 육상수조 사육방법보다 유의적으로 높았고 (P < 0.05), 육상수조 내 사육방법별 월별 중량변화는 유의적 차이가 없었다. 전복치패 각장의 일간성장률 (daily growth rate of shell length, <TEX>$DGR_{SL}$</TEX>), 특수생장율 (specific growth rate of shell length, <TEX>$SGR_{SL}$</TEX>) 에서도 NCC가 육상수조 실험구보다 유의적으로 높았으며 (P < 0.05), 각폭 성장에서의 성장률 (absolute growth rate of shell breadth, <TEX>$AGR_{SB}$</TEX>), <TEX>$DGR_{SB}$</TEX>, <TEX>$SGR_{SB}$</TEX>에서 NCC가 육상수조 내 실험보다 유의적으로 높았고 (P < 0.05), 육상수조 내 실험구간의 유의적 차이는 없었다. 육상수조 내 실험구에서 측정된 전복체중 성장은 FMW, WG, DWG, SWG에서는 각 실험구별로 유의적 차이가 없으며, 모든 실험구의 생존율은 실험종료 시 까지 55-60%를 유지하였다. 따라서 2 cm이상의 전복치패는 중간양성 시 동일한 밀도, 먹이를 공급한 육상수조 내에서는 차이를 보이지 않았지만, 신선한 먹이가 공급되면서 가두리 주위로 자연먹이가 풍부하게 자랐던 해상가두리가 성장에 유리하게 작용하였던 것으로 판단된다. This study was conduct to investigate the effect of Intermediate culture types on the growth and survival rate of the abalone, Haliotis discus hannai, in net cage and indoor tank. Intermediate cultures were to determine there that was to setting at marine net cage culture (NCC) in net cage, floor culture (FC), net floor culture (NFC), double shelter culture (DSC) and indoor net cage culture (INCC) in indoor tank, in two replicate. In the growth performance of juvenile abalone reared through intermediate culture, that the absolute growth rate (<TEX>$AGR_{SL}$</TEX>, <TEX>$AGR_{SB}$</TEX>), daily growth rate (<TEX>$DGR_{SL}$</TEX>, <TEX>$DGR_{SB}$</TEX>), and specific growth rate (<TEX>$SGR_{SL}$</TEX>, <TEX>$SGR_{SB}$</TEX>) to the shell length <TEX>$(_{SL})$</TEX> and shell breadth <TEX>$(_{SB})$</TEX> of NCC were higher than those of different groups (P < 0.05). As weight gain (WG), daily weight gain (DWG) and specific weight gain (SWG) to body weight through intermediate culture types in indoor tank was not significant. Also that, survival rate among experimental groups of intermediate culture in indoor tank was not significant. Therefore, these results is showed that should to cultivate for net cage so that intermediate culture of juvenile abalone over 2 cm, accordingly research to effective progress of juvenile abalone intermediate culture in indoor tank be should from various reason as well as feed and rearing condition.

Effect of dietary substitution of sea tangle (ST),Laminaria japonicawith rice bran (RB) on growth and body composition of juvenile abalone (Haliotis discus)

Dietary substitution effect of sea tangle (ST) with rice bran (RB) on growth and carcass composition of juvenile abalone (Haliotis discus) was determined. Juvenile abalone was acclimated to the experimental conditions for 4 weeks. Seventy juvenile abalone averaging 0.43 g were randomly distributed into each of the 18, 70 L plastic rectangular containers. The experimental diets were fed to abalone once a day at a satiation level with a little leftover. The feeding trial lasted for 16 weeks. Survival of abalone was not affected by dietary substitution of ST with RB. However, weight gain of abalone fed the RB40 diet was higher than that of abalone fed the all other diets except for the RB0 diet. No significant difference in weight gain was found in abalone fed between the RB0 and RB100 diets. SGR of abalone fed the RB40 diet was higher than that of abalone fed the all other diets. Also SGR of abalone fed the RB0 diet was higher than that of abalone fed the RB100 diet, but not different from that of abalone fed the RB20, RB60 and RB80 diets. Moisture, crude protein and ash content of the soft body of abalone were affected by dietary substitution of ST with RB. In conclusion, the 100% ST could be substituted with RB without a retardation of weight gain of abalone when the 20% ST was included into the experimental diet. However, the best growth performance was obtained in abalone fed the RB40 diet substituting 40% ST with RB.

Effects of dietary substitution of fishmeal with the combined dry microalgae,Nannochloropsis oceanica(NO) biomass residue and casein on growth and body composition of juvenile abalone (Haliotis discus)

The effects of dietary substitution of fishmeal with the combined dry Nannochloropsis oceanica (NO) biomass residue and casein on growth performance and carcass composition of juvenile abalone was determined. One thousand two hundred and sixty juvenile abalone were randomly distributed into the 18 L plastic rectangular containers. Five experimental diets in triplicate were prepared. The 28% fishmeal was included into the control (Con) diet. The 25%, 50%, 75% and 100% fishmeal were substituted with the combination of graded levels of dry NO biomass residue and casein, referred to as the NO25, NO50, NO75 and NO100 diets respectively. Finally, the salted sea tangle (ST), Laminaria japonica was prepared to compare the effect of the experimental diets on performance of abalone. The essential amino acids, such as isoleucine, leucine, phenylalanine, threonine and valine tended to increase with dietary substitution of fishmeal with NO biomass residue in the experimental diets. Arginine tended to decrease with dietary substitution of fishmeal with NO biomass residue. Survival of abalone fed the experimental diets was higher than that of abalone fed the ST diet for 16 weeks. Weight gain and specific growth rate (SGR) of abalone fed the NO100 diet were higher than those of abalone fed the all other diets. Weight gain and SGR of abalone linearly increased with dietary substation of fishmeal with NO. Shell length of abalone tended to increase with dietary substitution of fishmeal with the combined dry NO biomass residue and casein. The chemical composition of the soft body of abalone was different among treatments except for moisture content. In conclusion, fishmeal in the diets for abalone could be completely replaced with the combined dry NO biomass residue and casein when the 28% fishmeal was included.

Los lípidos en la nutrición del abulón azul, molusco con potencial de cultivo

The effect of type and level of lipids in the growth and metabolism of fatty acids in blue abalone was studied. The first part of the study was conducted in a commercial farm, where three dietary treatments (formulated diet, seaweed and both) were evaluated on biological parameters and fatty acid composition in the tissue of juvenile abalone, over a 329-day period. The fatty acid profiles of the abalone suggest their ability to synthesize long chain polyunsaturated fatty acids n-3 and n-6 from short-chained fatty acids. In the second experiment, the effect of lipid source and level, from four different edible oils, on growth and tissue fatty acid composition was evaluated. No significant differences in growth were found among abalone fed the different level or oil types but fatty acid requirements n-3 and n-6 were determined.

Inclusion of Distillers Dried Grain as Partial Replacement of Wheat Flour and Soybean Meal in the Diet of Juvenile Abalone Haliotis discus hannai

An 8-week feeding experiment was conducted to determine the influence of dietary distillers dried grain (DDG) on the growth and body composition of juvenile abalone Haliotis discus hannai. Five diets were formulated to contain 0% (DDG0), 15% (DDG15), 30% (DDG30), 45% (DDG45), and 60% (DDG60) DDG, and three replicate groups of abalone (average body weight: 3.6 ± 0.21 g) were fed one of the experimental diets at a feeding rate of 5% body weight per day once daily (17:00 h) for 8 weeks. Survival, shell length, and shell width of juvenile abalone were not affected by dietary DDG levels (P > 0.05). Weight gains of juvenile abalone fed DDG15 and DDG30 diets were not different compared to DDG0, but abalone fed DDG45 and DDG60 diets gained less weight than those fed DDG0 (P 0.05). The results of this experiment suggest that DDG is a good replacement for wheat flour and soybean meal, and can be used up to 30% in the diet to maintain the growth performance of the juvenile abalone.

Effects of different diet combinations on the growth of juvenile abalone (Haliotis asinina Linnaeus)

Abalones are common herbivores found throughout temperate and tropical waters; however, the diet composition of juvenile abalones remains unclear. This study aimed to evaluate the effects of four different macroalgae (Gracilaria tenuistipitata, Laminaria japonica, Gelidium japonica, and Sargassum sp.) on the feed intake and feeding rate of juvenile Haliotis asinina Linnaeus (H. asinina), and the effect of these macroalgae on abalone food choice as single or combined diets. Juveniles of H. asinina with mean initial weight and shell length of 5.2±0.9g and 24.2±0.7mm, respectively, were selected, and the experiments lasted for approximately 100 days. In trial 1, there were four treatments, and each supplied with a single macroalgal species with 24h fasting; in trial 2, all four macroalgal species were supplied together with 24h fasting; in trial 3, the juveniles were fasted for an additional 24h before supplying a single diet to explore the effect of the fasting; and in trial 4, different combinations of macroalgae were supplied as diet for biological evaluation of factors, including daily rate of shell increase, weight growth rate, specific growth rate, and feed conversion efficiency. Comparison of different feed intakes, feeding rates, and selection rates suggested that H. asinina juveniles showed different feeding preferences for the different macroalgae. The most consumed diet was G. japonica (red algae), followed by G. tenuistipitata (red algae), and L. japonica (brown algae), and finally, Sargassum sp. (brown algae). The results of trial 4 suggested that mixed feeds had better effects than single diets (P<0.05), and the best diet combination was L. japonica and G. tenuistipitata.

해양 산성화 및 수온 상승 환경에서의 전복치패(Haliotis discus hannai)의 생존 및 성장

The increasing of atmospheric <TEX>$CO_2$</TEX> are changing the pH (ocean acidification) and temperature of the sea. Although the effects of ocean acidification on calcifying organisms have well-documented, only a few studies have examined the combined effects of ocean acidification and elevated temperature. This study investigated the effects of ocean acidification and elevated temperature for 2100 on survival and growth of juvenile abalone, Haliotis discus hannai. Ocean acidification was simulated by bubbling <TEX>$CO_2$</TEX> into seawater at concentrations of 1,000 and 1,500 ppm, and temperature was set at room temperature <TEX>$+2^{\circ}C$</TEX>. Neither <TEX>$CO_2$</TEX> nor temperature had a significant effect on survival of abalone, while both significantly affected growth. There was no significant interaction between the two factors. Shell length can be used as a growth index of abalone to access the impacts of ocean acidification and elevated temperature.

Was overfishing of predatory fish responsible for a lobster-induced regime shift in the Benguela?

The top-down effects of predators have been demonstrated for terrestrial, freshwater and marine systems and their removal can cause a shift in ecosystem state. In many cases, the depletion of top-predators occurred long before humans began monitoring these systems, but models can elucidate likely ecosystem changes. In this paper we use a multispecies model to demonstrate that the abundance of predators can induce different ecosystem states, emphasising the importance of sustainable harvesting. Our model is founded on empirical data documenting a regime-shift that took place in the kelp-forest ecosystem along the south-west coast of South Africa following an ‘invasion’ by the West Coast rock lobster Jasus lalandii in the early 1990s. Formerly dominated by herbivores and encrusting corallines, the ecosystem became dominated by lobsters and macroalgae. A combination of illegal fishing of abalone Haliotis midae and the lobster-induced extermination of the urchin Parechinus angulosus (which shelters juvenile abalone) depleted abalone stocks severely. In this currently over-fished ecosystem where predators of lobsters are scarce, the regime-shift appears irreversible. Using an intermediate complexity model of lobster, urchin and abalone relationships, we simulated the effects of predatory fish at various population levels on the course of development of the currently lobster-dominated system. Our results indicate that current levels of fish biomass (<10% of the pristine population) would have been too small to significantly affect the lobster population. However, at pristine levels of fish abundance (or even 50% less), the invasion of lobsters would have been controlled by linefish, and urchin and abalone populations would not have collapsed. The effect of the lobster invasion had a greater influence on abalone abundance than illegal fishing, but together they severely depleted the abalone. Ecosystem effects of historical exploitation of top predators are of central concern, and our ecosystem model indicates that depletion of linefish had severe consequences for lobsters, urchins and abalone, illustrating how overfishing of top predators may precipitate regime shifts, with profound socio-economic consequences.

The effects of intermittent exposure to low-pH and low-oxygen conditions on survival and growth of juvenile red abalone

Abstract. Exposure of nearshore animals to hypoxic, low-pH waters upwelled from below the continental shelf and advected near the coast may be stressful to marine organisms and lead to impaired physiological performance. We mimicked upwelling conditions in the laboratory and tested the effect of fluctuating exposure to water with low-pH and/or low-oxygen levels on the mortality and growth of juvenile red abalone (Haliotis rufescens, shell length 5–10 mm). Mortality rates of juvenile abalone exposed to low-pH (7.5, total scale) and low-O2 (40% saturation, mg L−1) conditions for periods of 3 to 6 h every 3–5 days over 2 weeks did not differ from those exposed to control conditions (O2: 100% saturation, 12 mg L−1; pH 8.0). However, when exposure was extended to 24 h, twice over a 15-day period, juveniles experienced 5–20% higher mortality in the low-oxygen treatments compared to control conditions. Growth rates were reduced significantly when juveniles were exposed to low-oxygen and low-pH treatments. Furthermore, individual variation of growth rate increased when juveniles were exposed simultaneously to low-pH and low-O2 conditions. These results indicate that prolonged exposure to low-oxygen levels is detrimental for the survival of red abalone, whereas pH is a crucial factor for their growth. However, the high individual variation in growth rate under low levels of both pH and oxygen suggests that cryptic phenotypic plasticity may promote resistance to prolonged upwelling conditions by a portion of the population.

Evaluation of Post-Release Behavior, Recapture, and Growth Rates of Hatchery-Reared Abalone Haliotis asinina Released in Sagay Marine Reserve, Philippines

The lucrative returns brought by abalone fisheries have caused overexploitation and decline of the wild population. In the Philippines, the Aquaculture Department of the Southeast Asian Fisheries Development Center has successfully produced Haliotis asinina seeds in the hatchery. Aside from utilizing these seeds in aquaculture, they are also being considered for future stock enhancement endeavors of the department. This study aimed to evaluate post release behavior, recapture and growth rates of hatchery-reared abalone juveniles released in the Sagay Marine Reserve. From the two release trials conducted, results showed that abalone of shell length >3.0 cm had lower mortality during onsite acclimation and utilized transport modules as temporary shelter for a shorter period after release. Both wild and hatchery-reared abalone preferred dead branching corals with encrusting algae as their habitat. Recapture rates were comparable between the wild (7.97%) and hatchery-reared (HR2) abalone (6.47%). Monthly growth rates were almost the same between wild (0.25 cm, 4.0 g), hatchery-reared (HR1: 0.27 cm, 4.6 g; HR2: 0.35 cm, 3.8 g) abalone. Moreover, hatchery-reared abalone were recaptured up to 513 days post-release, indicating viability of released stocks in the wild. Results of releases revealed that hatchery-reared abalone can grow and survive with their wild conspecifics.

해상가두리 및 실내 육상수조에서 북방전복, Haliotis discus hannai 치패의 적정 수용밀도에 관한 연구

전복 치패의 성장은 해상가두리의 경우 <TEX>$m^2$</TEX> 당 150마리 실험구에서 <TEX>$60.53{\pm}5.75$</TEX> mm로 가장 빨랐고, 300마리 <TEX>$54.01{\pm}5.17$</TEX> mm, 450마리 <TEX>$51.48{\pm}5.37$</TEX> mm 및 600마리 <TEX>$51.09{\pm}4.96$</TEX> mm 순으로 나타났다. 육상수조의 경우 <TEX>$m^2$</TEX> 당 150마리 실험구에서 <TEX>$47.50{\pm}6.31$</TEX> mm로 가장 빨랐고, 300마리 <TEX>$45.92{\pm}5.23$</TEX> mm, 450마리 <TEX>$44.24{\pm}5.59$</TEX> mm 및 600마리 <TEX>$43.62{\pm}4.44$</TEX> mm 순으로 나타났다. 생존율은 모든 실험구에서 97.9% 이상으로 나타나 유의적인 차이는 보이지 않았다. 실험 결과 실험개시 후 3개월 이전에는 성장 차이가 나지 않았으나, 3개월 이후에는 성장 차이가 나타나기 시작하여 6개월부터는 뚜렷한 차이를 보였다. 특히 고밀도 실험구인 450마리 및 600마리에서는 3개월 후부터 성장이 둔화되는 경향이 나타났고, 비교적 낮은 300마리 실험구에서도 6개월 후부터 150마리 실험구에 비해 성장이 둔화되는 경향이 나타났다. 본 실험의 결과를 종합하여 전복 가두리양식에 적용하면 일반적인 수용밀도인 <TEX>$m^2$</TEX> 당 300마리 (<TEX>$2.4{\times}2.4$</TEX> m, 1칸당 1,500마리) 로 1년간 사육 후 분조하는 방법에서는 사육개시 6개월 이후부터 성장이 급격히 둔화 될 것으로 생각된다. 그러므로 기존의 1년 후 분조하는 방법으로 사육할 경우는 <TEX>$m^2$</TEX> 당 150마리 (<TEX>$2.4{\times}2.4$</TEX> m, 1칸 당 750마리) 가 적정 수용밀도라 생각되고, 기존의 수용밀도인 <TEX>$m^2$</TEX> 당 300마리로 사육할 경우 6개월 후 분조하여 밀도를 낮출 필요가 있으며, 이러한 방법을 전복 가두리양식에 적용하는 것이 양식 생산성 향상에 도움이 될 것으로 판단된다. Experiments for net cage culture at sea were conducted in each <TEX>$2.4{\times}2.4$</TEX> m in area and took the samples from four different densities: 150, 300, 450 and 600 per cross-sectional area (<TEX>$m^2$</TEX>) of shelter. The same stocking densities applied to indoor tank culture to investigate the growth and survival rate. The size of juvenile abalone sample was <TEX>$36.14{\pm}2.28$</TEX> mm for net cage culture and <TEX>$38.62{\pm}3.22$</TEX> mm or indoor tank. Feed such as raw brown sea mustard, raw kelp and dried kelp was sufficiently provided to the abalone. In net cage culture experiment, the growth of the spat of juvenile abalone was the fastest <TEX>$60.53{\pm}5.75$</TEX> mm in the 150 abalone cage per square meter (<TEX>$m^2$</TEX>), followed by the 300 abalone cage at <TEX>$54.01{\pm}5.17$</TEX> mm, 450 abalone cage at <TEX>$51.48{\pm}5.37$</TEX> mm and 600 abalone cage at <TEX>$51.09{\pm}4.96$</TEX> mm in order. In the meantime, in the indoor tank experiment, the 150 abalone indoor tank was the fastest <TEX>$47.50{\pm}6.31$</TEX> mm per square meter, followed by the 300 abalone tank at <TEX>$45.92{\pm}5.23$</TEX> mm, the 450 abalone tank at <TEX>$44.24{\pm}5.59$</TEX> mm and the 600 abalone tank at <TEX>$43.62{\pm}4.44$</TEX> mm in order. The survival rate was more than 97.9% in all the experiments, not showing a significant difference.

수온 및 염분별 노출시간에 따른 북방전복, Haliotis discus hannai 치패의 회복률 및 아가미의 조직학적 변화

본 연구는 저염분 해수에 노출된 전복의 폐사 원인을 구명하고자, 수온별 (15, 20 및 <TEX>$25^{\circ}C$</TEX>) 염분별 (30, 25, 20 및 15 psu) 노출시간별 (3, 6, 12, 24 및 48 h) 북방전복, Haliotis discus hannai 치패의 회복률 및 아가미의 조직학적 변화를 조사하였다. 모든 수온조건에서 20 psu 이하의 저염분 해수에 6시간 이상 노출시킨 전복은 회복기간 동안 생존율이 감소하였으며, 15 psu 해수에 24시간 이상 노출시킨 전복은 회복되지 못하고 전량 폐사하였다. 이를 조직학적으로 관찰한 결과, 20 psu 이하의 저염분 해수에 6시간 이상 노출시킨 전복의 아가미 조직은 팽창 또는 손상되었으며, 15 psu 해수에 24시간 이상 노출시킨 전복의 아가미 조직은 대부분 파괴되었다. 이와같은 결과는 수온이 높을수록, 염분이 낮을수록, 노출시간이 길수록 확연히 나타났다. 따라서 저염분 해수에 노출된 전복이 폐사하는 직접적인 원인 중의 하나는 아가미 조직의 손상으로 인한 질식으로 판단된다. This study looked into recovery rate and histological changes in the gills of juvenile abalone Haliotis discus hannai by exposure time (3, 6, 12, 24 and 48 h) of different water temperatures (15, 20 and <TEX>$25^{\circ}C$</TEX>) and salinities (30, 25, 20 and 15 psu) to understand reasons for the death of abalone exposed by low salinity water. In each water temperature, abalone spats that were exposed to low salinity water (less than 20 psu) for over 6 hours showed decrease in survival rate during recovery and those were exposed at the salinity of 15 psu for more than 24 hours all died. Histological observation showed expansion or damage of gills of the species which were exposed at less than 20 psu for over 6 hours. In case of abalones exposed at the salinity of 15 psu for over 24 hours, most gill tissues were destroyed. This result was glaringly obvious at a higher water temperature, lower salinity and longer exposure time. Accordingly, suffocation caused by damage of gills considered one of direct causes of the death.

Investigating the Translocation and Seeding of WildHaliotis mariaeWood, 1828, in the Sultanate of Oman

Restocking and potential stock enhancement of natural abalone stocks by seeding hatchery-reared juvenile abalone into suitable habitat is currently being investigated or implemented in a number of countries, including Japan, Australia, New Zealand, Mexico, and South Africa. A series of experiments has been conducted to investigate the feasibility and development of the technology required to do this in the Sultanate of Oman. Wild seed were collected between Mirbat and Ras Atian on the Dhofar coast and kept in a hatchery for 7 wk. Qualitative and observational data were used to develop seeding site selection criteria and a seeding density of 10 juveniles/m2. The juveniles were relocated and seeded in 18 different sites spread over a distance of 72 km. Sites selected with an abundance of boulders with a diameter of less than 50 cm yielded the highest recovery rates. Different categories of habitat availability and selection by seeded juveniles for specific habitat categories varied significantly among sites, which was reflected in the range of recovery rates. Boulder habitats less than 50 cm in diameter supported the most recovered juveniles (P = 0.002 and P = 0.005). Survival rates over a period of 30, 60, and 90 days ranged from 0%–80% and proved highly site specific (P = 0.04). A positive correlation was found between average seed size and increased recovery rates (P = 0.015, R2 = 0.25). Dispersal was limited in sites with high recovery rates. Site selection was shown to be vital. A simple seeding mechanism comprising a PVC tube proves successful as an alternative to seeding by hand.

Habitat complexity mediates predation of juvenile abalone by starfish

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 487:101-111 (2013) - DOI: https://doi.org/10.3354/meps10380 Habitat complexity mediates predation of juvenile abalone by starfish J. David Aguirre1,2,*, Douglas C. McNaught1,3 1School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand 2Present address: School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia 3Present address: University of Maine at Machias, Environmental and Biological Sciences Division, Machias, Maine 04654, USA *Email: d.aguirre@uq.edu.au ABSTRACT: Predation strongly influences the abundance and distribution of prey populations due to its disproportionately large effects on survival during the early life-history stages. However, the intensity of predation can vary dramatically among habitats. The habitat can directly affect the interaction between predator and prey; but also, by determining the distributions of predators and prey, the habitat can mediate the likelihood of a predatory encounter. Here, we used laboratory experiments to identify the likely predators of juvenile abalone Haliotis iris on temperate reefs in central New Zealand. Predator performance in the laboratory was assessed in conditions without prey refuge, in simulated juvenile habitat as well as in the presence of alternate prey. We then used surveys to compare the abundance of predators and juvenile abalone to explore if negative associations between predator and prey in the laboratory manifest in the field. Last, we manipulated algal habitat complexity at 2 depths and quantified the effect of predator exclusion on juvenile abalone survival in the field. We found that starfish were the likely predators of juvenile H. iris in our study system. Furthermore, predation of juvenile abalone by starfish was lowest in habitats with the greatest structural complexity, and there is evidence that predation by starfish in cobble habitats was size-dependent. Overall, we found that habitat variability mediates predation on juvenile abalone by determining the likelihood of an encounter between predator and prey. KEY WORDS: Barrens · Macroalgae · Urchin · Haliotis · New Zealand Full text in pdf format PreviousNextCite this article as: Aguirre JD, McNaught DC (2013) Habitat complexity mediates predation of juvenile abalone by starfish. Mar Ecol Prog Ser 487:101-111. https://doi.org/10.3354/meps10380 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 487. Online publication date: July 30, 2013 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2013 Inter-Research.

Effect of lipid composition of diets and environmental temperature on the performance and fatty acid composition of juvenile European abalone (Haliotis tuberculata L. 1758)

Juvenile abalone Haliotis tuberculata groups hatched in the lab from wild broodstock were fed with diets free of long chain polyunsaturated fatty acids (LC-PUFAs) (restriction diet) but with high amount of molecular precursors like 18:3n-3 and 18:2n-6 from linseed and corn oils compared to a control diet formulated with fish oil. Three different temperatures (12, 16 and 20°C) were chosen to measure the effect of fatty acid accumulation or synthesis compared to the control diet. After 200days of experimentation, abalone exhibited different growth between each temperature, whereas no differences were observed between diets. However, a higher fatty acid accumulation was observed in muscle tissue at 12°C. The relative amount of long chain polyunsaturated fatty acids (LC-PUFAs) in the muscle tissue was similar between those individuals fed with the restriction (LC-PUFA free) and full diets. This was clearly observed within the LC-PUFAs eicosapentaenoic acid (EPA) and docosapentaenoic acid (DPA), but not with docosahexaenoic acid (DHA), suggesting that H. tuberculata is able to synthesize the former FAs from their precursors. This pattern was also observed with arachidonic acid (ARA). In general abalone is able to synthesize and accumulate the necessary fatty acids to sustain growth at a wide range of temperatures and dietary sources, especially at lower temperatures, that could mean that this species is able to cope with a broad range of environmental conditions. However, DHA requirement in the H. tuberculata seems to be much inferior than previously reported, and its biosynthesis is undetectable under the present experimental conditions.

Effect of copper on the immunomodulatory activities of haemocytes in juveniles of the abalone Haliotis rufescens cultivated under hatchery conditions

The effect of short-term exposure to copper on the cellular and physiological response in haemocytes of juvenile abalone Haliotis rufescens cultivated in hatcheries in the north of Chile is evaluated. The animals were exposed for 168hours to concentrations of 2.5μg/L and 10μg/L of Cu+2, which have been reported as representative of coastal zones close to mining activity, particularly copper mining. The haemocytes were collected from the animals and the effect of the metal was quantified through the total haemocyte count (THC), phagocytosis, phenoloxidase activity, and generation of superoxide anions. The results showed that copper exposure decreased THC and phagocytosis significantly, while phenoloxidase activity and superoxide anions production increased significantly with respect to untreated controls. This study suggests a relation between exposure to the trace copper concentrations and the alterations of in vitro cellular and physiological parameters of the abalone's immune system in a dose- and time-dependent manner. This study emphasize the importance of heavy metal contamination on abalone cultures considering that the haemocytes are crucial for the proper function of the immune system and important health indicators to evaluate the effect of ambient stress factors on these organisms.

Effects of dietary grape seed oil and linseed oil on growth, muscle fatty acid composition and expression of putative Δ5 fatty acyl desaturase in abalone Haliotis discus hannai Ino

A 120-day feeding trial was conducted to investigate the effects of dietary increasing levels of grape seed oil (GO) and linseed oil (LO), rich in linoleic acid (LA) and α-linolenic acid (ALA) respectively, on growth, fatty acid composition and expression levels of putative Δ5 fatty acyl desaturases (Fads) in muscle of juvenile abalone (Haliotis discus hannai Ino). Seven experimental diets were formulated to contain increasing amounts (0%, 0.875%, 1.75% and 3.5%) of GO or LO as dietary lipids. Tripalmitin (TP), rich in 16:0, was supplemented to reach 3.5% (dry weight) total lipid. These diets were named as 0%GO/LO (TP), 25%GO, 50%GO, 100%GO, 25%LO, 50%LO and 100%LO. With the increase of dietary GO or LO inclusion, growth parameters (such as specific growth rate of weight) first increased and then decreased (R2>0.72, P=0.000). The survival rate of abalone was not significantly correlated with dietary GO (R2=0.04, P=0.815) or LO inclusion (R2=0.50, P=0.046). The contents of muscle n-6 polyunsaturated fatty acids (PUFA), including LA, 20:2n-6, 20:4n-6, 22:2n-6, were significantly positive correlated with dietary GO inclusion (R2>0.895, P=0.000). A positive relationship was significantly noted between the values of muscle n-3 PUFA (ALA, 20:3n-3, 20:5n-3 and 22:5n-3) and the dietary LO inclusion (R2>0.905, P=0.000). DHA was significantly increased and then decreased with dietary LO increase (R2=0.937, P=0.000). The expression levels of putative Δ5 Fads in 50%GO group were significantly higher than those of other GO groups (P<0.05). With the increase of dietary LO, expressions of putative Δ5 Fads first increased and thereafter reached a plateau (R2>0.929, P=0.000). These results indicated that biosynthesis of long chain polyunsaturated fatty acid in muscle of abalone could be increased in response to increasing levels of dietary LA or ALA through increased expressions of putative Δ5 Fads. High intakes of dietary LA and/or ALA inhibited the biosynthesis of DHA and compromised the growth performance of abalone.

Cryptic invertebrates on subtidal rocky reefs vary with microhabitat structure and protection from fishing

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 481:93-104 (2013) - DOI: https://doi.org/10.3354/meps10263 Cryptic invertebrates on subtidal rocky reefs vary with microhabitat structure and protection from fishing Timothy J. Alexander* Institute of Marine and Antarctic Studies, University of Tasmania, GPO Box 252, Private Bag 49, Hobart, Tasmania 7001, Australia *Email: tjalexander001@gmail.com ABSTRACT: The deployment of flat concrete blocks on subtidal rocky reefs can replicate natural reef microhabitats and provides a means for standardized sampling of cryptic invertebrates. The shape of the cavity beneath the block is related to reef topography and may influence the invertebrate community by affecting the amount of space for cryptic fauna to colonise and influencing the effectiveness of their predator-defence mechanisms. To determine the effect of sub-block reef structure and different levels of external predators on cryptic molluscs and echinoderms, I deployed concrete blocks at locations inside and outside the Maria Island marine reserve in eastern Tasmania, Australia. Relationships between sub-block reef structure and the cryptic invertebrate assemblage were evident between locations, whereas only a small but significant proportion of variation of assemblages between blocks within location was explained by reef surface area. No clear association with external predation pressure was evident in multivariate analyses of variation in assemblage structure. Juvenile abalone Haliotis rubra were not influenced by microhabitat structure but were significantly less abundant at protected locations, the only species to exhibit such a response. This result follows a decline of emergent adult abalone in the marine reserve and raises the possibility of recruitment failure of abalone at some fully protected locations in the longer term. KEY WORDS: Cryptic species · Marine reserve · Abalone · Boulders · Echinoderms · Molluscs Full text in pdf format PreviousNextCite this article as: Alexander TJ (2013) Cryptic invertebrates on subtidal rocky reefs vary with microhabitat structure and protection from fishing. Mar Ecol Prog Ser 481:93-104. https://doi.org/10.3354/meps10263 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 481. Online publication date: May 07, 2013 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2013 Inter-Research.

Effects of dietary supplementation of probiotic Shewanella colwelliana WA64, Shewanella olleyana WA65 on the innate immunity and disease resistance of abalone, Haliotis discus hannai Ino

The effects of dietary administration of two probiotics, Shewanella colwelliana WA64 and Shewanella olleyana WA65, on the innate immunity of abalone (Haliotis discus hannai Ino), and survival of juvenile abalone challenged with Vibrio harveyi have been studied. Two groups of abalone were fed with three different diets: one control, and two diets supplemented with 109 cell g−1 of probiotic WA64 (WA64 diet) and WA65 (WA65 diet) for up to four weeks. Results showed that abalone fed diets containing S. colwelliana WA64 and S. olleyana WA65 had led to an enhanced cellular and humoral immune response, notably higher haemocytes, respiratory burst activity, serum lysozyme activity and total protein levels were recorded after one week of probiotic administration. On the other hand, mortality after the challenges with V. harveyi in the group fed with control diet ranged from 77 to 80%, while mortality rates observed in the groups fed with diets supplemented with WA64 and WA65 ranged from 27 to 50% and 30–43%, respectively. The results demonstrated potential for S. colwelliana WA64 and S. olleyana WA65 to improve innate immunity and disease resistance in H. discus hannai.

Improving Outplanting Designs for Northern Abalone (Haliotiskamtschatkana): The Addition of Complex Substrate Increases Survival

ABSTRACT Hatchery-reared abalone outplanted into the wild at higher than ambient densities often experience very high levels of mortality as a result of density-dependent predation by natural predators. We conducted 2 experiments to assess the effectiveness of different methods of reducing predation on outplanted northern abalone (Haliotis kamtschatkana). During the first experiment, we removed small predators from brick-filled habitat cages that excluded large predators. The survival rates of juvenile abalone (mean shell length (SL), 22 mm) were greater in cages from which sea stars and other predators were removed periodically than in control cages. During the second experiment, we constructed 30 fenced 1 -m2 outplanting plots and assigned 10 randomly to be controls and 20 to be filled with 1 of 4 complex substrates (0.3-m layer of cobbles, 0.3-m layer of boulders, 0.9-m layer of cobbles, and 0.9-m layer of boulders). We then released 30 large juvenile abalone (mean SL, 51.5 mm) into each plot. The numb...