Balanus Tintinnabulum Research Articles

Growth and reproduction of Megabalanus tintinnabulum (Crustacea: Cirripedia) in coastal waters of Pakistan, North Arabian Sea

The growth and reproductive/ brooding pattern of Megabalanus tintinnabulum were studied from January 2012 to December 2013 on two rocky shores, Buleji and Manora, Karachi, the northern Arabian Sea. Population parameters were estimated using the von Bertalanffy growth function (VBGF) and ELEFAN 1 with the aid of FiSAT software. The population of M. tintinnabulum showed variability in density, size and growth rates between two rocky shores. The average density of M. tintinnabulum was higher at Buleji (101.9 ± 15.02 individual m−2) than Manora (76.0 ± 8.05 individual m−2). Though the estimated asymptomatic length (L∞) of M. tintinnabulum was 51.98 mm at both sites, the growth coefficient (K) value was higher at Manora (0.63 year−1) than Buleji (0.44 year−1). The population of M. tintinnabulum grew at a faster rate attaining the length of 31.8 mm in one year at Manora as compared to length of 23.7 mm at Buelji. Longevity (A0.95) in M. tintinnabulum was 4.8 years at Manora and 6.8 years at Buleji, while the longevity (A0.99) was higher at both sites being 7.3 years at Manora and 10.5 years at Buleji. The natural mortality rate (M) was 1.131 year−1 and 0.894 year−1 at Manora and Buleji, respectively. Though mature ovaries and testes were found throughout the year but the brooding individuals were observed during the winter (November to February) period showing that lower temperatures (20–24ºC) are preferred over higher temperatures (29–34ºC). The brooding capacity was same at two rocky shores but the numbers of brooders were higher at Manora than Buleji. The reproductive capacity was 7914 ± 303 of eggs per brood.

The first mitochondrial genome of Megabalanus tintinnabulum (Sessilia: Balanidae) from China: phylogeny within Cirripedia based on mitochondrial genes

Here we present the complete mitochondrial genome of Megabalanus tintinnabulum. The genome is 15,107 bp in length with a 67.35% AT content. It contains 13 protein-coding genes (PCGs), 2 rRNAs genes, and 22 tRNAs. Both rRNAs are encoded on the light strand, as in the other crustacean and barnacle mitochondrial genomes. Besides five tRNAs are encoded on the light strand (nad1, trnV, trnL1, trnC, trnQ, and trnK). Only one PCG is encoded on the light strand (nad1), whereas the other 12 PCGs are located on the heavy strand, which is consistent with M. ajax. Phylogenetic analysis based on mitochondrial PCGs shows that M. tintinnabulum is clustered with M. ajax into a branch (BP = 100), and the group with M. volcano with high support. This study contributes to further phylogenetic analysis within Cirripedia.

Diel Variations in Cell Abundance and Trophic Transfer of Diarrheic Toxins during a Massive Dinophysis Bloom in Southern Brazil.

Dinophysis spp. are a major source of diarrheic toxins to marine food webs, especially during blooms. This study documented the occurrence, in late May 2016, of a massive toxic bloom of the Dinophysis acuminata complex along the southern coast of Brazil, associated with an episode of marked salinity stratification. The study tracked the daily vertical distribution of Dinophysis spp. cells and their ciliate prey, Mesodinium cf. rubrum, and quantified the amount of lipophilic toxins present in seston and accumulated by various marine organisms in the food web. The abundance of the D. acuminata complex reached 43 × 104 cells·L−1 at 1.0 m depth at the peak of the bloom. Maximum cell densities of cryptophyceans and M. cf. rubrum (>500 × 104 and 18 × 104 cell·L−1, respectively) were recorded on the first day of sampling, one week before the peak in abundance of the D. acuminata complex. The diarrheic toxin okadaic acid (OA) was the only toxin detected during the bloom, attaining unprecedented, high concentrations of up to 829 µg·L−1 in seston, and 143 ± 93 pg·cell−1 in individually picked cells of the D. acuminata complex. Suspension-feeders such as the mussel, Perna perna, and barnacle, Megabalanus tintinnabulum, accumulated maximum OA levels (up to 578.4 and 21.9 µg total OA·Kg−1, respectively) during early bloom stages, whereas predators and detritivores such as Caprellidae amphipods (154.6 µg·Kg−1), Stramonita haemastoma gastropods (111.6 µg·Kg−1), Pilumnus spinosissimus crabs (33.4 µg·Kg−1) and a commercially important species of shrimp, Xiphopenaeus kroyeri (7.2 µg·Kg−1), only incorporated OA from mid- to late bloom stages. Conjugated forms of OA were dominant (>70%) in most organisms, except in blenny fish, Hypleurochilus fissicornis, and polychaetes, Pseudonereis palpata (up to 59.3 and 164.6 µg total OA·Kg−1, respectively), which contained mostly free-OA throughout the bloom. Although algal toxins are only regulated in bivalves during toxic blooms in most countries, including Brazil, this study indicates that human seafood consumers might be exposed to moderate toxin levels from a variety of other vectors during intense toxic outbreaks.

Macro-Fouling Faunal Assemblage in Hambantota Port

Invasive species recognized as one of the greatest threats to global biodiversity and biofouling on submerged structures within a port environments is one of the major pathways of invasions by Non Indigenous Species (NIS). Early detection and monitoring of such deleterious organisms is crucial, since control is nearly impossible once established. The present work is a baseline study for biofouling faunal assemblage in Hambantota Port. The study consisted of two stages; initial sampling for investigating existing biofouling assemblage and review sampling after 10 months in order to monitor the changes in community structure. Sampling followed an international protocol developed by Center for Research on Introduced Marine Pest (CRIMP). Samples were scraped from submerged hard substrata in 12 sampling sites with the assistance from divers. Organisms in scraped samples were identified to the nearest taxonomic level using taxonomic guides and databases. All together 90 species were recorded during the study. Among them, 72 species were recorded within the baseline sampling and additional 18 during review sampling. Highest number of species recorded from phylum Mollusca (54) followed by Arthropoda (11), Annelida (11), Chordata (5), Cnidaria (4),Echinodermata (3) and Bryozoa (2). Balanus amphitrite, Balanus tintinnabulum, were the most common species in baseline sampling while Chthamalus sp.1 and Cellana radiata in the review sampling. Balanus tintinnabulum, Clypidina notata, Cellana radiata, Thais echinata, Harmoniconus parvatus and Saccostrea cucullata were the common species found in both sampling. In baseline sampling, highest number of species was recorded from Oil Pier (31) while least number (1) was recorded in the outer harbour artificial island. In review sampling, highest species richness (12) recorded in west bank while least species richness (5) was recorded within the West Breakwater. The most noteworthy finding is that eight globally known invasive species which include, Rapana venosa, Phallusia nigra, Perna perna, Brachidontes pharaonis, Balanus amphitrite, Balanus reticulates, Balanus trigonus and Schizoporella errata were recorded. Among them Rapana venosa was recorded only in review sampling and rest in baseline sampling. Keywords: Biofouling, Non-indigenous species, Baseline study, Hambantota Port

The diversity of acorn barnacles (Cirripedia, Balanomorpha) across Thailand’s coasts: The Andaman Sea and the Gulf of Thailand

The acorn barnacle is a sessile crustacean, inhabiting the intertidal areas of tropical and temperate regions worldwide. According to current practices on Cirripedia morphology, shell, opercular valves, and arthropodal characters including cirri and mouthparts are used as a tool for taxonomic classification, and using these characteristics the present study aimed to provide better resolution for the barnacle diversity and geographical distribution within coastlines of Thailand: the Andaman Sea and the Gulf of Thailand. A total of ten species belonging to three families (Chthamalidae, Tetraclitidae, and Balanidae) were identified in this study. Subsequently, five species were newly recorded for the first time from Thailand’s coasts: Newmanella spinosus Chan & Cheang, 2016, Euraphia hembeli Conrad, 1837, Euraphia depressa (Poli, 1795), Tetraclita kuroshioensis Chan, Tsang & Chu, 2007, and Tetraclita singaporensis Chan, Tsang & Chu, 2007. The others, already mentioned in previous records, include: Tetraclita squamosa (Bruguière, 1789), Chthamalus malayensis Pilsbry, 1916, Amphibalanus amphitrite (Darwin, 1854), Amphibalanus reticulatus (Utinomi, 1967), and Megabalanus tintinnabulum (Linnaeus, 1758). Interestingly, acorn barnacles along the Andaman Sea occur abundantly, and are much higher in number of species (up to 8 species) than those found in the Gulf of Thailand’s coast (up to 6 species). This biased trend of species’ preferences is possibly due to the differences in oceanographic nature between two coastlines and the history of barnacle colonization.

Marine communities on oil platforms in Gabon, West Africa: high biodiversity oases in a low biodiversity environment.

The marine biodiversity of Gabon, West Africa has not been well studied and is largely unknown. Our examination of marine communities associated with oil platforms in Gabon is the first scientific investigation of these structures and highlights the unique ecosystems associated with them. A number of species previously unknown to Gabonese waters were recorded during our surveys on these platforms. Clear distinctions in benthic communities were observed between older, larger platforms in the north and newer platforms to the south or closer to shore. The former were dominated by a solitary cup coral, Tubastraea sp., whereas the latter were dominated by the barnacle Megabalanus tintinnabulum, but with more diverse benthic assemblages compared to the northerly platforms. Previous work documented the presence of limited zooxanthellated scleractinian corals on natural rocky substrate in Gabon but none were recorded on platforms. Total estimated fish biomass on these platforms exceeded one ton at some locations and was dominated by barracuda (Sphyraena spp.), jacks (Carangids), and rainbow runner (Elagatis bipinnulata). Thirty-four percent of fish species observed on these platforms are new records for Gabon and 6% are new to tropical West Africa. Fish assemblages closely associated with platforms had distinct amphi-Atlantic affinities and platforms likely extend the distribution of these species into coastal West Africa. At least one potential invasive species, the snowflake coral (Carijoa riisei), was observed on the platforms. Oil platforms may act as stepping stones, increasing regional biodiversity and production but they may also be vectors for invasive species. Gabon is a world leader in terrestrial conservation with a network of protected areas covering >10% of the country. Oil exploration and biodiversity conservation currently co-exist in terrestrial and freshwater ecosystems in Gabon. Efforts to increase marine protection in Gabon may benefit by including oil platforms in the marine protected area design process.

An illustrated guide to the fossil barnacles (Cirripedia) from the Crags (Plio-Pleistocene) of East Anglia

The Plio-Pleistocene Crag deposits of East Anglia include a wealth of shelly remains, including barnacles, preserved variously as complete shells, their disarticulated plates and trace fossils. Herein, we present a field guide to these distinctive fossils, with diagnoses of all known taxa recorded from the Crags of East Anglia, supported by both line drawings and photographs. The known stratigraphic and geographic distribution within the study area are tabulated. Recognised species include the sessile barnacles Armatobalanus bisulcatus (Darwin), A. dolossus (Darwin), Balanus balanus (Linné), B. crenatus Bruguière, B. inclusus Darwin, Concavus concavus (Bronn), Chirona hameri (Ascanius), Megabalanus tintinnabulum (Linné), Conopea calceola (Ellis), Co. spongicola (Brown), Acasta undulata Darwin, Coronula barbara Darwin, Megatrema anglicum (G.B. Sowerby) and Verruca stroemia (Müller) (=14 species); two pedunculate forms, Scalpellum magnum Darwin and Lepas delicatula Withers; and the boring Rogerella isp. The greatest diversity of species is found in the Coralline Crag and Red Crag formations, both yielding 11 species, although only four are common to both. Barnacles are poorly represented in other Crag deposits.

Algal epibiosis on Megabalanus tintinnabulum and its role in segregation of the Balanus amphitrite population

AbstractUlva sp. and Gracilaria sp. were found colonizing shell surfaces of an acorn barnacle, Megabalanus tintinnabulum. However, this association was not noticed in the case of Balanus amphitrite, which was a co‐inhabitant. Such a difference in intergeneric interactions with the algae was examined in laboratory experiments. For this, the influence that extracts of algae, extracts of algae‐associated bacteria and natural leachants from M. tintinnabulum exerted on cyprid metamorphosis of B. amphitrite was examined. Extracts of algae and associated bacteria showed no effect on the metamorphosis of B. amphitrite. This may be attributed to absence of cue‐specific sugars in the exopolysaccharides and culture supernatants of bacteria. On the other hand, natural leachants of M. tintinnabulum, which showed the presence of N‐acetyl‐d‐glucosamine, a known algal spore attractant, also inhibited metamorphosis of B. amphitrite. Thus, hosting specific epibionts could have important roles in the segregation of barnacle population.

Fouling acorn barnacles in China—a review

We review the species composition, distribution, and seasonal variation of fouling acorn barnacles in Chinese waters—from Bohai Sea and Yellow Sea to East and South China Seas. Thirty-two species of acorn barnacles were found, of which, the dominant species are Amphibalanus amphitrite, A. reticulatus, A. variegates, Balanus trigonus, Fistulobalanus kondakovi, Megabalanus tintinnabulum, Striatobalanus amaryllis, and Eurapha withersi in the fouling communities. A. amphitrite is the dominant species in the coastal waters of Bohai Sea and Yellow Sea and A. reticulatus is dominant in the East and South China Seas. The settlement period of fouling acorn barnacles is usually in summer and autumn. From north to south with the decrease of latitude, their settlement period obviously extends, even to the whole year, and the species number also increases. Other environmental factors, such as salinity and distance from shore, also play an important role in the distribution of fouling acorn barnacles.

New Mediterranean Marine biodiversity records (June 2013)

This paper concerns records of species that have extended their distribution in the Mediterranean Sea. The finding of the rare brackish angiosperm Althenia filiformis in the island of Cyprus is interesting since its insertion in the Red Data Book of the Flora of Cyprus is suggested. The following species enriched the flora or fauna lists of the relevant countries: the red alga Sebdenia dichotoma (Greece), the hydrachnid mite Pontarachna adriatica (Slovenia), and the thalassinid Gebiacantha talismani (Turkey). Several alien species were recorded in new Mediterranean localities. The record of the burrowing goby Trypauchen vagina in the North Levantine Sea (Turkish coast), suggests the start of spreading of this Lessepsian immigrant in the Mediterranean Sea. The findings of the following species indicate the extension of their occurrence in the Mediterranean Sea: the foraminifer Amphistegina lobifera (island of Zakynthos, Greece), the medusa Cassiopea andromeda (Syria), the copepod Centropages furcatus (Aegean Sea), the decapod shrimp Melicertus hathor (island of Kastellorizo, Greece), the crab Menoethius monoceros (Gulf of Tunis), the barnacles Balanus trigonus, Megabalanus tintinnabulum, Megabalanus coccopoma and the bivalves Chama asperella, Cucurbitula cymbium (Saronikos Gulf, Greece).

Crustáceos asociados a sustrato duro en la zona intermareal de Montepío, Veracruz, México

The rocky intertidal zone is the habitat of a number of species due to its spatial heterogeneity. In this study the crustacean species richness at Montepio is presented based on samples obtained monthly from February 1996 to February 1997, and bimonthly from July 2004 to July 2005, and deposited in the National Crustacean Collection, Instituto de Biologia, UNAM. A total of 4 437 organisms was identifi ed, grouped in 19 families, 36 genera and 60 species. The families with the highest number of species were Alpheidae with 11 species, Porcellanidae with 7, Gammaridae with 6, the rest of the families contributed with the remaining 60% of the species. Regarding the density, the following species had the highest values: Tetraclita stalactifera floridana (457 org/l), Megabalanus tintinnabulum (318 org/l), Elasmopus sp. 1 (280 org/l) and Neopisosoma angustifrons (267 org/l). It was determined through an Olmstead-Tukey analysis that 65% of the species were occasional, 12% dominant, 20% common and 3% indicator. Species richness in Montepio is lower than those for other areas in the Gulf of Mexico and the Pacific coast with rocky substrates.

DESCRIPTION OF THE NAUPLIAR STAGES OF MEGABALANUS TINTINNABULUM (CIRRIPEDIA: BALANIDAE)

Larval development of Megabalanus tintinnabulum was studied in the laboratory. At 26 ? 1 ?C the development from nauplius I-VI required about 4 days, when the diatom Chaetoceros wighami was used as food. Detailed morphological drawings and setation formulae of appendages of all 6 naupliar stages are presented for the first time. Notable features of the nauplii include the presence of a spinulated lateral margin, a trilobed labrum with teeth, long dorsal and posterior shield spines, a single tooth on the inner prong of the antennal gnathobase, comb-shaped cuspidate setae on the antennae, and spines and simple denticulate setae on the mandibular endopodite in naupliar stage II. The present description of the nauplii is not in full agreement with the previous description of this species from this coast by Daniel (1958). Differences in stage sizes, naupliar morphology, and setation of appendages are used to distinguish this species from other megabalanines and the nauplii of megabalanines from those of balanines in the Balanus amphitrite group.

Miocene barnacle assemblages from southern Spain and their palaeoenvironmental significance

The Tabernas Basin in southeast Spain is a Neogene intermontane basin which filled with sub-aerial and submarine fan conglomerates grading into turbidite sandstones towards the basin centre. The basin history involved the development of Seravallian-Tortonian subaerial fans which coalesced southwards from the basin margin. Increasing water depth in the Tortonian led to a submarine development of these fans. The coarse fan conglomerates are colonized almost solely by barnacles of the species Megabalanus tintinnabulum, known from Miocene-Recent deposits. The barnacles occur in seven preservational-state assemblages, which provide a record of the colonization of stabilized mass-flow conglomerates and of subsequent reworking episodes. M. tintinnabulum is known from intertidal environments today. In situ clusters developed on the fan conglomerates record the transition of the fans from subaerial to submarine environments. Mass-flow deposits rich in barnacle shell debris are representative of basin-wards reworking of intertidal clusters and illustrate relative increase in water depth. A further shallowing episode is identifiable by the recolonization of mass flows by in situ barnacle clusters. This case history is demonstrative of the utility of some barnacles in determining basin history with respect to minor sea level fluctuations.

Sublethal response of barnacles to chlorine: An experimental study for power plant biofouling control

Results of the study on sublethal responses of Megabalanus tintinnabulum, an acorn barnacle exposed to different levels of chlorine, is presented. In control, juvenile barnacles showed increased filtration rates, cirral activity and oxygen consumption per unit body weight as compared to larger barnacles. When both the size groups were exposed to chlorine levels, filtration rates and cirral activity declined. In larger barnacles the decline in filtration and cirral activity was less prominent. A decline in oxygen consumption observed in larger barnacles appears to be due to anaerobic metabolism under chlorinated conditions, when shell valves close. Juveniles appear to have normal oxygen consumption rates and thus may be more prone to stress.

Response of barnacles to chlorine and heat treatment: An experimental study for power plant biofouling control

Results of a study on mortality response of Megabalanus tintinnabulum when exposed to chlorine and different temperatures are presented. At 1.5 ppm chlorine residuals, 5 mm barnacles showed 100% mortality in 101 h and 30 mm barnacles in 156 h. At relatively high levels of chlorine residuals (15 ppm), all the size groups showed 50% and 100% mortality at identical exposure times. Exposure to a temperature of 35°C showed 100% mortality of the 5 mm size group in 9.9 h and 50% mortality in 3.98 h. All the size groups showed 100% mortality at identical exposure times above 40°C. While chlorination appears to be the method of choice in operating power plants, heat treatment can be considered for use in new plants. The heat treatment method that is reportedly successful in California can be more economical if practised in India. This paper emphasises application of the two methods in power plants and the need for more biological information to control power plant biofouling in Indian waters.

Palaeoecology and significance of barnacles in the mid‐Pliocene Balanus Bed of Tobago, West Indies

AbstractThe Balanus Bed of the Rockly Bay Formation (mid‐Pliocene) of Tobago is a sequence of orange‐brown sands with laterally equivalent muds. The invertebrate macrofauna is dominated by the balanid barnacle Megabalanus tintinnabulum (Linnaeus) sensu lato, with associated oysters, pectinaceans, gastropods, bryozoans, regular echinoids, and rare crabs and sharks. Vertical burrows in muddier substrates are good evidence that this assemblage was living littorally or shallowly sublittorially. Previous analyses of the Rockly Bay Formation of the type area have erroneously suggested that it represents a lenticular deposit. It is now recognized to be a transgressive unit, unconformable on the underlying Mesozoic basalts. The sediment of the Balanus Beds was derived from the in situ weathering of basalts, producing a gradation from sandy (near shore) to muddy substrates. Balanids grew singly on the weathering basalt, but suitable substrates for attachment in the muddy environment were rare, so barnacles are found clustered in close association. The primary substrates for attachment in the muddy environment were disarticulated balanid plates, mollusc valves and small pebbles. Although the base of the Formation is not seen in Rockly Bay, a basal conglomerate overlain by a horizon of dissociated valves of the large ark Anadara patricia (Sowerby) is exposed in nearby Little Rockly Bay. Apart from the two fossiliferous horizons mentioned, the Formation is barren of marine microinvertebrates. The Rockly Bay Formation appears to have formed in response to the mid‐Pliocene rise in sea level. Horizons dominated by balanids may be useful indicators of sea‐level rise, at least in the Neogene, Darwin's ‘Age of Barnacles’.

Copper toxicity in tropical barnacles, Balanus Amphitrite amphitrite and Balanus tintinnabulum tintinnabulum

The effect of Cu on survival time, O2 consumption and accumulation of Cu in barnacles, Balanus amphitrite amphitrite and Balanus tintinnabulum tintinnabulum was studied. B. amphitrite amphitrite were found to survive longer than B. tintinnabulum tintinnabulum at all concentrations of Cu. Copper reduced the O2 consumption of both barnacles, but the reduction was greater with B. tintinnabulum tintinnabulum. Copper accumulation in soft parts of the barnacles increased with increasing Cu concentration and time. The barnacles accumulated Cu up to a particular limit (166.7 ± 8.98 μg g−1 in B. amphitrite amphitrite and 173.6 ± 12.17 μg g−1 in B. tintinnabulum tintinnabulum) at all Cu concentrations beyond which they died.

Depth Zonation, Micro habitat, and Morphology of Three Species of Acanthemblemaria (Pisces: Blennioidea) in the Guif of California, Mexico

Abstract. The utilization of the spatial resources of refuge type, size and depth placement is investigated in the three sympatric species of Acanthemblemaria at the cape region of Baja California, Mexico. A. balanorum occupies barnacle testes (Balanus tintinnabulum), A. macrospilus occupies barnacles and mollusk tubes (vermetid gastropods and pholadids), and A. crockeri occupies only mollusk tubes (pholadids). Refuge diameter overlap is higher than overlap in depth. A. crockeri consistently occupies depths below 5m. Competition experiments for barnacle refuges among the three species indicate that A. balanorum is a superior competitor for such refuges. Prior residency of a less superior species changes the outcome of refuge competition in its favor. The morphological specialization of A. balanorum and A. macrospilus is evident in a high correlation between head size and standard length. A. balanorum selects refuges with entrance diameters highly correlated to standard length.

A new look at variation in Darwin's species of acorn barnacles

Darwin's studies on barnacles, begun to satisfy his curiosity about specimens from the Beagle, but later extended to the large collections of other naturalists, lasted for 8 years and produced a set of definitive monographs. Darwin was particularly troubled over the taxonomy of two groups of acorn barnacles, Balanus tintinnabulum and B. amphitrite, which he ultimately classified as clusters of wellmarked varieties. Recent studies, based on established taxonomic methods or on statistical treatment of morphometric data, suggest these are clusters of full species and that the ‘intermediate’ forms are just phenotypic variants. Darwin was also troubled by the small chthamalid intertidal barnacles, which he eventually grouped as varieties of a world-wide species, Chthamalus stellatur. Gel electrophoresis and morphometrics now show this to be a heterogenous assemblage of distinct species, some very different, others closer together, all with restricted geographical range, but all showing extreme variability in the characters normally used for classification. Darwin's difficulties with the classification of the highly varying barnacles, and his anatomical studies on these peculiar animals, must have had considerable influence on the development of his theories about natural selection, more than is usually acknowledged by writers on evolution. These ‘lost years’ were in fact a period of intense zoological enquiry, and Darwin's change in attitude with regard to species and variation in nature underwent a big change, as can be seen from the letters and from the differences between the early drafts written before the barnacle work and the later Natural Selection and The Origin. Whether we regard the difficult groups of Balanus as clusters of species or clusters of varieties, they still draw attention to evolutionary processes as in Darwin's day.

Fundamental Studies on Control of Marine Fouling Organisms by Sea Urchin

Grazing activity of sea urchins, Strongylocentrotus nudus and St. intermedius, which were fed marine fouling organisms, was obserbed. Mussel, Mytilus edulis galloprovincialis, and barnacles, Balanus tintinnabulum, B. rostratus and B. trigonus, were eaten by sea urchins. A linear relation was found between the maximum diameter of the mouth of sea urchins (d mm) and the the maximum shell length of the mussels (l mm). The mussels were eaten completely in the case of l≤d. The maximum number of mussels eaten was 15/day/sea urchin. The mussels were eaten partially in the case of d 1.75d. Averege number of barnacles scraped was 3.3/day/sea urchin. B. tintinnabulum of thin shell was eaten better than B. trigonus and B. rostratus of thick shell. When a sea urchin was introduced into the netting cage of cultured scallop, Patinopecten yessoensis, the sea urchin fed on encrusting bryozoans and compound ascidians as well as slime fouled on the shell surface of the scallop. Thus, the grazing activity of the sea urchins is applicable to controlling fouling organisms on cultured scallop.