Red Abalone Haliotis Rufescens Research Articles

Underwater adhesion of abalone: The role of van der Waals and capillary forces

The observation of the pedal foot of the red abalone Haliotis rufescens reveals the presence of micrometer-scaled setae terminating in nanometer-sized cylindrical fibrils, with some resemblance to those found on the gecko foot. Atomic force microscopy (AFM) pull-off force measurements on a single seta are compared with theoretical estimates for van der Waals attraction obtained through the Johnson–Kendall–Roberts (JKR) equation, approximately 600 nN, and show agreement. The use of the JKR equation is justified through an analysis of the shape of the fibril extremities (parabolic) as well as their diameter (∼200 nm). Measurements under varying humidity conditions indicate that additional capillary interactions play a role, since the pull-off force increases with humidity. It is proposed that both van der Waals and capillary forces play a role in the attachment mechanism of H. rufescens, effectively enabling suction to reach its theoretical limit. Bulk pull-off force measurements on entire live animals yield an average detachment stress of 115 kPa, consistent with theoretical estimates. The setae and nanoscale fibril terminations enable compliance to surfaces with a variety of roughnesses, effectively sealing the interface, in addition to providing capillary and van der Waals forces.

The randomized response technique as a tool for estimating non-compliance rates in fisheries: a case study of illegal red abalone (Haliotis rufescens) fishing in Northern California

SUMMARYIllegal fishing has detrimental environmental and social impacts, but these effects are difficult to mitigate without reliable estimates of fisher non-compliance. Methods used by fisheries managers to estimate illegal fishing often require indirect estimation of poaching using biological, economic or sociological indicators. This study presents a unique application of the randomized response technique (RRT) for direct estimation of non-compliance in fisheries to the Northern California recreational red abalone (Haliotis rufescens) fishery. An anonymous paper-based compliance and sociodemographic survey of recreational fishers in Sonoma and Mendocino Counties estimated 29% non-compliance with the daily take limit, 23% with the minimum size limit, 19% with licensing laws and 15% with the annual take limit. RRT results also indicated how different sociodemographic characteristics related to non-compliance. Visitors had higher non-compliance rates than local fishers for all regulations except daily take limits, which an estimated 72% of locals violated versus 18% of visitors. High fisher awareness of regulations, fisher age, income and fishing experience did not appear to influence illegal take. RRT is a powerful tool which can aid conservation managers in prioritizing action.

Fishing from past to present: continuity and resilience of red abalone fisheries on the Channel Islands, California

Archaeological data from coastal shell middens provide a window into the structure of ancient marine ecosystems and the nature of human impacts on fisheries that often span millennia. For decades Channel Island archaeologists have studied Middle Holocene shell middens visually dominated by large and often whole shells of the red abalone (Haliotis rufescens). Here we use modern ecological data, historical accounts, commercial red abalone catch records, and zooarchaeological data to examine long-term spatial and temporal variation in the productivity of red abalone fisheries on the Northern Channel Islands, California (USA). Historical patterns of abundance, in which red abalone densities increase from east to west through the islands, extend deep into the Holocene. The correlation of historical and archaeological data argue for long-term spatial continuity in productive red abalone fisheries and a resilience of abalone populations despite dramatic ecological changes and intensive human predation spanning more than 8000 years. Archaeological, historical, and ecological data suggest that California kelp forests and red abalone populations are structured by a complex combination of top-down and bottom-up controls.

Interfacial shear strength in abalone nacre

The shear strength of the interface between tiles of aragonite in the nacre of red abalone Haliotis rufescens was investigated through mechanical tensile and shear tests. Dog-bone shaped samples were used to determine the tensile strength of nacre when loaded parallel to the plane of growth; the mean strength was 65 MPa. Shear tests were conducted on a special fixture with a shear gap of 200 μm, approximately 100 μm narrower than the spacing between mesolayers. The shear strength is found to be 36.9±15.8 MPa with an average maximum shear strain of 0.3. Assuming the majority of failure occurs through tile pull-out and not through tile fracture, the tensile strength can be converted into a shear strength of 50.9 MPa. Three mechanisms of failure at the tile interfaces are discussed: fracture of mineral bridges, toughening due to friction created through nanoasperities, and toughening due to organic glue. An additional mechanism is fracture through individual tiles.

Gradual Ordering in Red Abalone Nacre

Red abalone (Haliotis rufescens) nacre is a layered composite biomineral that contains crystalline aragonite tablets confined by organic layers. Nacre is intensely studied because its biologically controlled microarchitecture gives rise to remarkable strength and toughness, but the mechanisms leading to its formation are not well understood. Here we present synchrotron spectromicroscopy experiments revealing that stacks of aragonite tablet crystals in nacre are misoriented with respect to each other. Quantitative measurements of crystal orientation, tablet size, and tablet stacking direction show that orientational ordering occurs not abruptly but gradually over a distance of 50 microm. Several lines of evidence indicate that different crystal orientations imply different tablet growth rates during nacre formation. A theoretical model based on kinetic and gradual selection of the fastest growth rates produces results in qualitative and quantitative agreement with the experimental data and therefore demonstrates that ordering in nacre is a result of crystal growth kinetics and competition either in addition or to the exclusion of templation by acidic proteins as previously assumed. As in other natural evolving kinetic systems, selection of the fastest-growing stacks of tablets occurs gradually in space and time. These results suggest that the self-ordering of the mineral phase, which may occur completely independently of biological or organic-molecule control, is fundamental in nacre formation.

Effect of eight benthic diatoms as feed on the growth of red abalone (Haliotis rufescens) postlarvae

The growth rate of abalone post larvae of Haliotis rufescens fed ad libitum with a benthic monoalgal diatom culture maintained as monocultures on a semi-commercial scale, was evaluated and correlated with the biochemical composition of the diatoms. The cell size (7.0 × 4.0 µm to 21.0 × 7.5 µm), protein percentage (7.42% to 13.66%), and ash content (49.03% to 59.61%) were different among diatom strains; lipid percentage, nitrogen free extract, and energy content (Kcal g−1) were similar among diatom strains. The values of essential and non-essential amino and fatty acids composition differed among diatom strains. Differences in the abalone shell length and orthogonal analyses revealed postlarval growth was dependent on the quality of the food source. Postlarvae abalone displaying the longest shell lengths were fed Nitzschia thermalis var. minor and Amphiprora paludosa var. hyalina (1,712.0 ± 61 µm and 1,709 ± 67 µm, respectively), followed by Navicula incerta (1,413.3 ± 43 µm). The fatty acid content of benthic diatoms and abalone growth rate were not correlated.

Exploring the Use of a Size‐Based Egg‐per‐Recruit Model for the Red Abalone Fishery in California

AbstractEggs‐per‐recruit (EPR) models are widely used for management of invertebrate fisheries to provide guidance to managers about the magnitude of egg production for a given level of instantaneous annual fishing mortality (F). We constructed a deterministic size‐based EPR model that utilizes size‐specific natural mortality rates and egg production for red abalone Haliotis rufescens in California. We analyzed the sensitivity of the model to alterations in biological parameters, modeled the effect of incidental mortality of sublegal individuals on EPR, and modeled the effects of various management actions, including incorporation of a slot size limit, incorporation of a harvest refugium, and alternative legal minimum size limits. Model results were more sensitive to alterations in growth parameters and lower mortality estimates than to changes in upper mortality estimates or fecundity parameters. When F increased from 0.0 to 0.1 per year, EPR exhibited a large decline from 100% to 70%. Only the incorporation of a harvest refugium and an increase in the minimum size limit produced increases in the percent of maximum EPR. Implementing a slot limit of 152.4–203.2 mm maximum shell length (MSL) decreased the EPR value, indicating the importance of egg production by red abalone that are smaller than the current minimum size limit of 177.8 mm MSL. Because of the sensitivity of model predictions to changes in certain biological parameters, we recommend caution when applying EPR models to management, particularly for regions without spatially explicit parameter values. Despite this sensitivity, EPR models provide a heuristic framework for exploring the potential impacts of proposed fishery management strategies (e.g., harvest refugia), establishing biological reference points, examining how spatial and temporal variability in biological parameters affects egg production, and providing a guide for prioritizing research to improve data quality used for red abalone management.

Organic–inorganic interfaces and spiral growth in nacre

Nacre, the crown jewel of natural materials, has been extensively studied owing to its remarkable physical properties for over 160 years. Yet, the precise structural features governing its extraordinary strength and its growth mechanism remain elusive. In this paper, we present a series of observations pertaining to the red abalone (Haliotis rufescens) shell's organic–inorganic interface, organic interlayer morphology and properties, large-area crystal domain orientations and nacre growth. In particular, we describe unique lateral nano-growths and paired screw dislocations in the aragonite layers, and demonstrate that the organic material sandwiched between aragonite platelets consists of multiple organic layers of varying nano-mechanical resilience. Based on these novel observations and analysis, we propose a spiral growth model that accounts for both [001] vertical propagation via helices that surround numerous screw dislocation cores and simultaneous 〈010〉 lateral growth of aragonite sheet structure. These new findings may aid in creating novel organic–inorganic micro/nano composites through synthetic or biomineralization pathways.

La experienca del desarrollo del cultivo de abalón (Haliotis spp.) en Chile : oportunidades y desafíos

Intensive abalone farming--specifically of the red abalone (Haliotis rufescens) and the green (or Japanese) abalone (Haliotis discus hannai)--has expanded rapidly in Chile since the late 1990s, and this article presents an overview of the challenges facing the industry and the factors which favour its development. At present, 100% of Chile's abalone enterprises farm the H. rufescens species, owing to its suitability for full-cycle culture. In the analysis of factors that facilitate the development of abalone farming in Chile, those that stand out include the characteristics of the aquatic ecosystem, existing entrepreneurial and professional skills, decisive government support in co-financing scientific and technological projects, infrastructure and associated services to support these development initiatives and a market where prices have remained stable and demand for abalone products has been steady. The greatest challenges facing intensive abalone farming in Chile are providing a constant supply of macroalgae for abalone feed and developing complementary feed, as well as updating current legislation on intensive abalone farming, strengthening producer associations and establishing health certification. The article discusses examples of the impact that native organisms can have on animals introduced into an aquatic ecosystem and the international transmission of agents such as withering syndrome and sabellid polychaete infestation disease, associated with the movement of abalone seeds and broodstock. The article also emphasises the importance of implementing the recommendations of the World Organisation for Animal Health.

Efficacy, tissue distribution, and residue depletion of oxytetracycline in WS-RLP infected California red abalone Haliotis rufescens

Oxytetracycline (OTC) was recently demonstrated to be an effective therapeutant for California red abalone ( Haliotis rufescens) infected with the agent of withering syndrome (WS), a Rickettsia-like prokaryote (WS-RLP). This study examined the influence of temperature on the efficacy and pharmacokinetics of oral OTC treatments on WS-RLP infected red abalone, H. rufescens. Medication was administered in an artificial diet containing 1.85% active OTC at a rate of 103.4 mg/kg abalone for 10, 20 and 30 days at both 13.4 °C and 17.3 °C. Drug residue concentrations, WS-RLP burden and WS-associated pathological changes within foot muscle and digestive gland were measured 3, 17, 23, 42, 63, 81, 102, 122, and 160 days after OTC treatment. In all samples the highest concentrations of OTC were detected on the first sample day. Furthermore, all sampling periods showed significantly less OTC in foot muscle samples relative to corresponding digestive gland samples ( p < 0.001). While drug depuration occurred rapidly from foot muscle, unusually high concentrations and long depuration times were measured within the digestive gland. The pharmacokinetic trends in both the foot muscle and digestive gland at 13.4 °C were adequately described by a one-compartment model, while the digestive gland depuration models within the 17.3 °C treatments conformed to a two-compartment model. At both temperatures treatment duration gave rise to significant differences in OTC accumulation and depletion ( p < 0.001). Despite this, terminal elimination rate constants were similar. Estimated half-lives were similar among all treatments for digestive gland (23.8–27.5 d) and all treatments for the foot muscle at 13.4 °C (10.7–13.4 d; calculated only for the 13.4 °C treatments). At both temperatures all three durations of drug treatment led to significant reductions in WS-RLP prevalence, foot muscle atrophy, and mortality. WS-RLP re-challenge trials initiated 44, 88, and 122 days following the 10-day treatment at 17.3 °C showed reduced susceptibility to re-infection for up to 88 days after treatment, suggesting that digestive gland OTC residues confer long-term resistance to pathogen. Atomic absorption spectroscopy conducted on both foot muscle and digestive gland found significantly higher concentrations of iron, zinc, and manganese in the digestive gland, offering an explanation behind the underlying mechanism of OTC retention for extended periods within this tissue.

Sex and flow: the consequences of fluid shear for sperm–egg interactions

Fertilization is a complex interaction among biological traits of gametes and physical properties of the fluid environment. At the scale of fertilization (0.01-1 mm), sperm encounter eggs while being transported within a laminar (or viscous) shear flow. Varying laminar-shear in a Taylor-Couette flow tank, our experiments simulated important aspects of small-scale turbulence within the natural habitats of red abalone (Haliotis rufescens), a large marine mollusk and external fertilizer. Behavioral interactions between individual cells, sperm-egg encounter rates, and fertilization success were quantified, simultaneously, using a custom-built infrared laser and computer-assisted video imaging system. Relative to still water, sperm swam faster and moved towards an egg surface, but only in comparatively slow flows. Encounter rate, swim speed and orientation, and fertilization success each peaked at the lowest shear tested (0.1 s(-1)), and then decayed as shear increased beyond 1.0 s(-1). The decay did not result, however, from damage to either sperm or eggs. Analytical and numerical models were used to estimate the propulsive force generated by sperm swimming (F(swim)) and the shear force produced by fluid motion within the vicinity of a rotating egg (F(shear)). To first order, male gametes were modeled as prolate spheroids. The ratio F(swim)/F(shear) was useful in explaining sperm-egg interactions. At low shears where F(swim)/F(shear)>1, sperm swam towards eggs, encounter rates were pronounced, and fertilization success was very high; behavior overpowered fluid motion. In contrast, sperm swimming, encounter rate and fertilization success all decayed rapidly when F(swim)/F(shear)<1; fluid motion dominated behavior. The shears maximizing fertilization success in the lab typically characterized natural flow microenvironments of spawning red abalone. Gamete behavior thus emerges as a critical determinant of sexual reproduction in the turbulent sea.

GO WITH THE FLOW

Red abalone ( Haliotis rufescens ) live deep in the cracks and crevices in rocky reefs, and have probably retreated there because of predation pressure from sea otters, who like how they taste almost as much as humans do. Abalone are external fertilisers, releasing eggs and sperm into the water,

THE INTRODUCED SABELLID POLYCHAETE TEREBRASABELLA HETEROUNCINATA IN CALIFORNIA: TRANSMISSION, METHODS OF CONTROL AND SURVEY FOR PRESENCE IN NATIVE GASTROPOD POPULATIONS

The sabellid polychaete Terebrasabella heterouncinata (Fitzhugh & Rouse 1999) has a unique life history in which larvae settle on the edge of gastropod shells and rely on shell deposition to create a tube with an opening to the exterior. This worm was accidentally imported to California, USA on abalone from South Africa in the 1980s and spread with abalone shipments to most culture facilities and some public aquaria throughout the state. Its ability to infest California's native gastropods has sparked concern regarding potential establishment in intertidal habitats adjacent to facilities that held sabellid-positive abalone. We examined the ability of T. heterouncinata to transmit between individual turban snails, Tegula funebralis. We found that transmission between T. funebralis did occur, but at a significantly slower rate than that between red abalone Haliotis rufescens. During 2002 to 2006 native gastropods (turban snails and limpets) were collected at most sabellid-exposed sites and no T. heterouncinata were detected; it thus appears that this species has not become established in California. Freshwater exposure was examined as a method to kill T. heterouncinata in shell fragments that may remain after abalone are removed from production or display units. Freshwater immersion for up to 8 hours but not 16 or 32 h resulted in survival of adults and/or larvae resident in brood chambers. In a similar study, motile T. heterouncinata larvae were found to survive up to 32 sec of freshwater exposure, whereas none survived a 64-sec exposure. These data can be used by abalone culture and display facilities to establish reliable sanitization procedures to prevent T. heterouncinata transmission or reinfestation.

DEVELOPMENT AND CURRENT STATUS OF ABALONE AQUACULTURE IN CHILE

Abalone aquaculture is rapidly developing in Chile although this mollusc does not occur naturally in this country. The red abalone Haliotis rufescens was introduced in 1977 and the ezo abalone Haliotis discus hannai in 1982. After several years of research and development, the industry began in 1992 and Chile is currently the fifth producer of cultured abalone in the world with 304 tons in 2006. Twenty five companies are involved in this Chilean industry, culturing mainly red abalone. Most of the farms in the North include hatcheries and land-based grow-out operations, whereas most of the in-water grow-out facilities are located in the South. All farms in Chile use algae as the main food for growing abalone, but artificial feeds are also used in some land-based operations in the North. The average size of abalone harvested in Chile is 8 cm (100-120 g) after 3-5 y in culture systems. Whole frozen abalone (shell on) is the most important form of this Chilean product (82% in 2006) and the main market is Japan (90.2%). Abalone production has increased at a rate of around 50% per annum over the last 3 y. This development is expected to continue in the next years, fostered by favorable geographic, economic, and environmental conditions as well as an important government support to invest in abalone. A survey among producers revealed that feed availability and quality is currently considered a key issue to further develop this industry in Chile.

MOLECULAR MARKERS USED TO ANALYZE SPECIES-SPECIFIC STATUS IN ABALONES WITH AMBIGUOUS MORPHOLOGY

Pacific abalone (Haliotis discus hannai) and Californian red abalone (Haliotis rufescens) are easily distinguished by their shell and epipodial characteristics. A few individuals of H. rufescens were discovered to have epipodial coloration similar to that of H. discus hannai suggesting that they may have been hybrids of the two species, because hybridization of these species has been informally reported from local hatcheries. The present study uses molecular genetic methods to determine whether the rarely colored variants represented hybrids between the two species. Two hundred RAPD primers were tested with PCR on two DNA pools of eight individuals of each species. Primers that showed different amplification profiles between species were tested on 27 randomly sampled individuals of each species to check the existence of polymorphisms. Two primers differentiate both species. Primer 356 amplified an approximately 450 bp and 460 bp specifics-DNA fragments in H. discus hannai that were not present in red abalone, whereas primer 368 amplified a 750 bp, 850 bp, 860 bp, and 1,190 bp specific-DNA fragments in H. rufescens that were not present in H. discus hannai. The amplification pattern of the DNA of individuals with ambiguous morphology for both primers was characteristic of red abalone. The results strongly suggested that the specimens with unusual epipodial coloration were not hybrids, but rather, phenotypic variants of H. rufescens. Future studies should focus on the cause of the variation of epipodium color in H. rufescens, which could be either genetic polymorphism or phenotypic plasticity.

METAMORPHOSIS AND POSTLARVAL GROWTH OF ABALONE HALIOIS RUFESCENS IN A MEXICAN COMMERCIAL HATCHERY

Metamorphosis induction and postlarval growth of the red abalone (Haliotis rufescens) were evaluated in a commercial farm of Baja California, México. This hatchery settles larvae with gamma-aminobutyric acid (GABA, 1-μM final concentration) and culture postlarvae in 250-L tanks placed in a four-story structure inside a building with artificial illumination. Eight tanks (four at the top and four at the bottom of a culture structure) were sampled during four months after settlement. Upper tanks received more light than the lower tanks (means of 727 and 217 lux, respectively) and had a higher mean water temperature (14.9°C and 14.4°C, respectively). Estimates of metamorphosis induction were highly variable (37% to 99%) and mean values were higher in lower (76%) than in higher (54%) tanks. Potential causes of this unexpected variability are discussed. There was a significant positive linear relationship between metamorphosis induction and early (7-day) postlarval survival. Average postlarval growth rates were also highly variable among tanks (37–63 μm/day) and slightly higher in upper than in lower tanks (60 and 52 μm/day, respectively). During the sampling period, growth variability was positively associated with water temperature changes, especially after the formation of the first respiratory pore when growth increased abruptly.

Application of Recent Red Abalone HALIOTIS RUFESCENS Surveys to Management Decisions Outlined in the California Abalone Recovery and Management Plan

The management section of California's recently adopted Abalone Recovery and Management Plan (ARMP) uses results of fishery independent transect surveys at eight index sites to regulate total allowable catch (TAC) for the recreational red abalone, Haliotis rufescens (Swainson), fishery. The ARMP uses abalone densities over all depths, densities in deep water (8.4–19.7 m), and successful recruitment (>4,500 abalone/hectare in the 100–177 mm size class) to decide whether changes need to be made in the TAC (see Table 1 later). The catch is estimated from telephone surveys and returned abalone permit report cards. Recent surveys in 2003 and 2005 at four of the eight index sites show red abalone densities in the range of the baseline densities established by surveys in 1999 and 2000. Applying the results of the 2003 and 2005 surveys to the ARMP criteria indicates no change is needed in the current TAC. Two-way ANOVA showed there were no significant differences in density between sites (Van Damme and Salt Point; df = 1, F = 0.06, P > 0.8) and time periods (df = 1, F = 1.33, P > 0.25) for all depths combined. Likewise there were no significant differences at deep depths between the two sites (df = 1, F = 0.23, P > 0.63) and the two time periods (df = 1, F = 0.10, P > 0.75).

FIRST REPORT OF DODECACERIA SP. (POLYCHAETA: CIRRATULIDAE), IN RED ABALONE IN CHILE

This is the first time that the genus Dodecaceria is reported in shell galleries of the red abalone Haliotis rufescens. The worms measures up to 60-mm long with about 120 setigers and have a brown-greenish color. Previously Rozbaczylo and Carrasco (1996) mentioned the presence of this species in the shells of the gastropod molluscs Fissurella maxima and Concholepas concholepas and in the bivalve Aulacomya ater. Hernández et al. (2001) reported it in the shell of the barnacle Austromegabalanus psittacus in Concepción, Chile.

Genetic structure of natural populations of California red abalone (Haliotis rufescens) using multiple genetic markers

Mitochondrial cytochrome oxidase subunit one (COI) sequence, nuclear microsatellites, and amplified fragment length polymorphisms (AFLPs) were used to evaluate connectivity among nine red abalone (Haliotis rufescens) populations sampled between August 1998 and November 2003 along approximately 1,300 km of California coastline from Crescent City (41°46′N, 124°12′W) to San Miguel Island (34°02′N, 120°22′W). COI sequences and microsatellite genotypes did not show significant genetic divergence among nine sampled populations. A subset of five populations spanning the geographic range of the study was scored for 163 polymorphic AFLP markers. Of these, 41 loci showed significant divergence (P < 0.001) among populations. Still, no AFLP markers were diagnostic for any of the study populations, and assignment tests did not consistently assign individuals to the correct population. Although the AFLP data are the first to suggest there is significant genetic differentiation among California red abalone populations, the discordance between the different genetic markers needs further study before unambiguous conclusions can be drawn with respect to connectivity among the populations.

Fluorescence in situ hybridization of rDNA, telomeric (TTAGGG)n and (GATA)n repeats in the red abalone Haliotis rufescens (Archaeogastropoda: Haliotidae)

The physical location of 18S-5.8S-28S rDNA, telomeric sequences with (TTAGGG)n DNA probe and (GATA)n microsatellites were performed by fluorescence in situ hybridization in chromosomes of red abalone Haliotis rufescens. The karyotype of red abalone showed a diploid number of 36 (8M+9SM+1ST). FISH performed with rDNA probe, showed the location of major ribosomal clusters in the terminal region of the large arms of two submetacentric pairs (chromosome 4 and 5). Localization of heteromorphisms of FISH-rDNA was found between chromosome homologues and sister chromatids in all metaphases analyzed. This indicates that rDNA clusters are variable within the red abalone genome. The variability in the NOR-bearing reported using silver staining in other gastropods and our result are discussed. In addition, the presence of microsatellite (TTAGGG)n and (GATA)n was demonstrated after FISH treatment by DNA probes. The telomeric sequence occurred at the ends of all mitotic chromosomes, while the (GATA)n repetitive was found on chromosomal interstitial zones as well as at the telomeres in abalone chromosomes.