Dead Barnacles Research Articles

Effect of Barnacles on the Corrosion Behavior of 304 Stainless Steel

Wire-beam, potentiodynamic polarization, electrochemical impedance spectroscopy and surface corrosion morphology analysis techniques were used to investigate the corrosion characteristics of 304 stainless steel (304SS) specimens subjected to different degrees of fouling; these analyses were conducted to clarify the corrosive effects of biofilms and barnacles. The experimental results indicated that the gradual thickening of the biofilm reduces the corrosion rate of 304SS (Icorr = 0.0677 μA/cm2). Mature biofilm acts as a barrier and significantly increases the protection of the substrate (Z = 905,000 Ω·cm2). The corrosion mechanisms of 304SS fouled with barnacles at various stages of growth are distinct: the corrosion rates of the microelectrodes fouled by living and recently dead barnacles are low because the overall structure is still intact. This structure creates a closed environment between the barnacles and the metal, limiting the transfer of corrosive factors from the outside to the inside. Despite the influences of corrosive bacterial decomposition, the Ecorr values of recently dead barnacles dramatically decrease to −668.8 mV. The microelectrode covered by the empty-shell barnacles corrodes heavily. Bacteria decompose the barnacle body and calcite shell, and glue damages their originally closed structures. Direct contact between the metal and reactive ions occurs, resulting in the continuous ingress of Cl− into the cracks, which intensifies crevice corrosion.

Macrofouling induced localized corrosion of stainless steel in Singapore seawater

Biofouling induced corrosion of stainless steels grades UNS S31603 and UNS S31254 was investigated at three sites off Singapore for 30months. No corrosion was observed on grade UNS S31254, while the propensity for corrosion by shellfish of UNS S31603 is ranked as oyster>>barnacles>>green mussels. Oysters caused extensive localised corrosion, penetrating 2mm thick plates with 12months with tracks of corrosion several centimetres long.Shallow crevice corrosion was observed under dead barnacles, with an explanation presented for why corrosion is more severe under dead barnacles than live ones. Green mussels did not cause any corrosion.

Too close for comfort: spatial patterns in acorn barnacle populations

AbstractSpatial patterns in aggregations form as a result of the interplay between costs and benefits experienced by individuals. Such self‐organisation of aggregations can be explained using a zonal model in which a short‐range zone of repulsion and longer‐range zone of attraction surrounding individuals leads to emergent pattern properties. The signal of these processes can be detected using spatial pattern analyses. Furthermore, in sessile organisms, post‐settlement mortality reveals the relative costs and benefits of positions within the aggregation. Acorn barnacles are known to require contact with conspecifics for reproduction and are therefore believed to aggregate for this purpose; isolated individuals may also be more susceptible to abiotic stress and predation. At short distances, however, competition for space and resources is likely to occur. In this study spatial patterns of barnacles (Semibalanus balanoides L.) were analysed using pair‐correlation functions. Individuals were dispersed at distances below 0.30 cm, but peak relative density occurred at a distance of 0.36 cm from conspecifics. This is much closer than required for reproductive access, implying a strong aggregative drive, up to the point of physical contact with neighbours. Nevertheless, analysis of dead barnacles illustrated that such proximity carries a cost as barnacles with many neighbours were more likely to have died. The inferences obtained from these patterns are that barnacles aggregate as closely as they can, and that local neighbourhood competition is a powerful determinant of mortality. These processes give rise to the observed pattern properties.

Risks for larvae mediated by plasticity in hatching

AbstractRisks associated with benthic and planktonic development can be mediated by plasticity in hatching. The ability to delay hatching while awaiting favorable planktonic conditions, combined with the ability to accelerate hatching when encapsulated offspring are at risk, should be advantageous. We tested this predicted association of hatching plasticities with a barnacle. In the winter, broods of barnacles (Balanus glandula) reached hatching‐capable stages at widely varying times, but these broods hatched in the spring within about 2 weeks, consistent with a synchronizing environmental stimulus for hatching. In contrast, the same adults held subsequent broods (during later spring and summer) briefly. Either an environmental stimulus for hatching was not needed later in the season, or it was more frequently present. Dissections of brood lamellae that scattered smaller clumps of the encapsulated nauplii induced hatching. Crabs eating brooding adults had a similar effect: crabs broke the barnacles' tests, and many nauplii hatched. In contrast, when whelks ate barnacles, they left the barnacles' wall plates and opercula in place, and few nauplii were released. In some cases, numerous hatched nauplii were trapped within the test of the killed mother. At a field site with abundant whelks, many dead barnacles had opercular plates in place. Plasticity in hatching of broods adjusted risks for planktonic larvae against risks of death of the parent before release of embryos, but escape or death of brooded offspring depended on the kind of damage to the brooding mother and thus on the kind of predator. Although both predators killed brooding parents, subtle snails imposed a greater risk than crushing crabs.

Combining Traits and Density to Model Recruitment of Sessile Organisms

We propose an integrative approach that explains patterns of recruitment to adult populations in sessile organisms by considering the numbers of individuals and their body size. A recruitment model, based on a small number of parameters, was developed for sessile organisms and tested using the barnacle Semibalanus balanoides, a marine invertebrate inhabiting North Atlantic intertidal shores. Incorporating barnacle body size improved model fit beyond that based on density alone, showing that growth played an important role in how resource limitation affected survival. Our approach uncovered the following: First, changes in the shape of the recruitment curve resulted from the balance between individual growth and mortality. Second, recruitment was limited by the least plastic trait used to characterise body size, operculum area. Basal area, a trait that responded to increases in barnacle density, did not contribute significantly to explain patterns of recruitment. Third, some temporal variation is explained by changes in the amount of space occupied by shells of dead barnacles: at high cover barnacles are densely packed and these shells remain long after death. Fourth, seasonal variation and spatial variation in survival can be separated from that resulting from resource limitation; survival was predicted for two different shores and four sampling times using a single recruitment model. We conclude that applying this integrative approach to recruitment will lead to a considerable advance in understanding patterns of mortality of early stages of sessile organisms.

Patterns of substrata use by the invasive acorn barnacle Balanus glandula in Patagonian salt marshes

Balanus glandula is a native barnacle of the rocky shores in the west coast of North America. Forty years after its introduction in Argentina, this species is the only barnacle dominating the high intertidal of local rocky shores and more interesting, it was also reported successfully colonizing soft-bottom salt marshes. In this study, we identified and characterized the substrata most successfully colonized by B. glandula in Patagonian salt marshes through descriptive and experimental means. We surveyed and compared two Patagonian salt marshes and the substrata colonized by B. glandula. Our results show that barnacles utilize more than 10 types of different substrata. Mussel valves were the most frequent type of substrata utilized in Riacho marsh, whereas the dominant halophyte Sarcocornia perennis was the substratum most utilized in Fracasso marsh where mussels were mostly absent. When the five most utilized substrata were experimentally offered, the halophyte shrub Limonium brasiliense was the most densely colonized of the experimental substrata, with the largest sizes and the lowest proportion of dead barnacles. Density and size of the barnacles recruited on plants were similar to that observed in nearby invaded rocky shores. Our study strongly suggests that soft-bottom environments, where hard substrata are available, have to be seriously considered when designing early detection plans targeting B. glandula and other similar rocky shore invasive species.

Settlement of the gastropod Concholepas concholepas on shells of conspecific adults

Competent larvae of the commercially important marine gastropod Concholepas concholepas (Gastropoda: Muricidae) ‘loco’, were collected in the field and exposed in the laboratory to adult conspecific shells with and without barnacle epibionts. Settlement and metamorphosis was induced by the presence of barnacles on shells of live or dead conspecifics, but not by C. concholepas shells without barnacles. Results from laboratory experiments agreed well with field surveys showing the presence of recruits on conspecific shells overgrown with barnacles in shallow subtidal habitats (∼3–30 m deep), suggesting the potential importance of barnacles in inducing settlement and metamorphosis of locos under natural conditions. Most loco recruits were found below the C. concholepas shell apex, feeding on barnacles, inhabiting crevices among them, and inside dead barnacles. The mean size of recruits on locos' shells increased over four months from the beginning of the settlement season and no individual larger than 1·5 cm was observed, suggesting that they abandon adult loco shells at this size, roughly 5–6 months after settlement.

Sponge-inhabiting barnacles on Red Sea coral reefs

In this study eight different species of barnacles were found within nine species of sponges from the Red Sea. This brings to 11 the number of sponge-symbiotic barnacles reported from the Red Sea, two of these are new Acasta species (not described herein) and one (A. tzetlini Kolbasov) is a new record for this sea. This number is much higher than that of symbiotic barnacles found within sponges from either the N. Atlantic (2) or the Mediterranean (4). Two possible explanations for this are the presence of numerous predators in coral reefs and scarcity of available substrate for settlement. These factors can lead to high incidence of symbiotic relationships. Of the nine sponge species, only one (Suberites cf. clavatus) had previously been known to contain barnacles. Even at the family level, this is the first record of symbiotic barnacles in two out of the seven sponge families (Latrunculiidae, Theonellidae). Our present findings strengthen the apparent rule that the wider the openings in a barnacle shell, the fewer the host taxa with which it will associate, usually from one or two closely related families, and the more frequent it will associate with elastic sponges. Most Neoacasta laevigata found on Carteriospongia foliascens were located on the same side as the sponge's ostia, i.e. facing the incoming water. This adaptation allows the barnacles to catch more suspended particles from the water, provides them with more oxygen and prevents their exposure to discharged sponge waste. The highest density of barnacles observed on one face of a “leaf ” (with ostia) was 0.389 barnacles cm−2 (one barnacle per 2.57 cm2) and on average 0.181 ± 0.68, while the average on the other side was only 0.068 ± 0.52 barnacles cm−2. As indicated by the Morisita index, these barnacles most frequently (58%, n = 12) had a clumped spatial distribution (while the rest were randomly distributed), as is to be expected from such sessile organisms with internal fertilization via copulation. The presence of N. laevigata induced the growth of secondary perpendicular projections of its host C. foliascens. Of the N. laevigata examined, 17% brooded 324 ± 41 embryos each, of 286 ± 17 μm total length; only 5.7% (n = 123) were found to be dead. Size distribution analysis of skeletal elements from dead barnacles showed them to be significantly larger than the skeletal elements of the population of live barnacles ( p < 0.05).

POPULATION DYNAMICS OF THE BARNACLE BALANUS AMPHITRITE IN AN INTERTIDAL AREA AFFECTED BY SEWAGE POLLUTION

ABSTRACT Recruitment and mortality patterns in an intertidal population of Balanus amphitrite were studied for 4.5 years close to a sewage outfall near Quequen, Argentina. Recruitment occurred mainly during summer, although a small proportion of the population recruited in autumn. As a consequence of the failure of 4 successive annual recruitments, population density decreased almost steadily from 130 to 6 ind·m 2. With the exception of the postsettlement period, which was not considered in the present study, mortality was gradual during benthic life. The number of barnacles dying per unit time decreased as annual cohorts grew older. Mean longevity was estimated to be 22 months. Maximal longevity attained 5-6 years. Between 4 and 6 cohorts coexisted during the study period. The percentage of dead barnacles found with empty shells still attached to the substratum was higher in winter/spring than in summer/autumn, and increased with age. The causes of the extended life history of B. amphitrite at Quequen may be related to low temperature, low population density, and near absence of intraspecific competition and predation. The population studied seems to be regulated by recruitment and physical disturbance.

Recruitment, growth and mortality of a coral-inhabiting barnacle Megabalanus stultus (Darwin) upon the hydrocoral Millepora complanata Lamarck

The distribution and abundance of the coral-inhabiting barnacle Megabalanus stultus (Darwin) in Barbados were determined on the hydrocoral Millepora complanata Lamarck. Nine percent of the millepores examined were colonized, there was a mean of 2.58 barnacles per colony and adult barnacles were contagiously distributed. A positive correlation between the abundance of millepore colonies on reefs and the frequency of colonies bearing barnacles indicated that barnacle larvae were attracted to settlement sites in proportion to the density of the host millepore colonies. From size-frequency distributions and regressions it was determined that barnacles grew at the rate of 1.1 mm per month and attained a length of about 19 mm in 18 months. Recruitment was low compared to densities of recruits of shore barnacles reported elsewhere. Seventy-four percent of annual recruits occured upon the millepore colony length increment formed during the current year. It was concluded that settlement mortality was least near the growing edge of the host colony where the density of millepore predatory zooids was lowest. Mortality was higher during the second year than during the first year of growth and dead barnacles became overgrown by millepore skeleton and soft tissue. The low abundance of predators and the lack of inter- and intraspecific competition suggests that most adult mortality was due to age. In comparison to shore barnacles, the supply-side ecology of M. stultus was distinguished by lower recruitment, more rapid growth and settlement interaction with the host substratum, as well as a shorter adult life, lack of competition and escape from predators as adults.

Effects of human trampling on an exposed rocky shore

The effects of human pedestrian pressure on an exposed rocky shore lying within a newly‐declared marine reserve near Cape Town, South Africa, were investigated. Transects were marked across the intertidal zone of a little‐frequented section of the shore and subjected to trampling up to 500 times per month. Immediate effects of pedestrian impact included the dislodgement of dead barnacles, damage to algae and the crushing of small numbers of amphipods and isopods. Long‐term effects could, however, not be found, and those transects subject to the most intensive pressure did not differ significantly from a control area. A survey of types of footwear used by people walking in the intertidal indicated that over 85 percent used no footwear at all. This lack of protection forces the majority of pedestrians to proceed with caution in order to avoid injury, and sumultaneously minimises the damage they inflict on intertidal biota. It thus appears likely that wave action is of considerably greater importance to inte...

Differential predation by barnacles upon larvae of two bryozoans: spatial effects at small scales

In the laboratory, coronate larvae of the cellularoid bryozoan Bugula stolonifera Ryland are eaten by the barnacle Balanus eburneus Gould, whereas the larger larvae of Bugula neritina (Linnaeus) are rejected as food. We tested the potential effects of this differential predation in the field by comparing settlement of the two bryozoan species on shells of living and dead barnacles at three scales: among barnacles, among barnacle wall plates, and within wall plates. In neither species was there a significant difference in overall settlement density between living and dead barnacle shells, but the spatial distributions of both species were influenced by barnacle-feeding activities at the smallest scale. On living barnacles, settlement densities were generally lower on the rostral and carinal plates than on the lateral and carinolateral plates, but this pattern did not occur on dead barnacles. Because rejected larvae of B. neritina were ejected beyond the rostral plate, the same settlement distribution occurred for both vulnerable and invulnerable larval species. Thus, differential predation did not translate into species-specific settlement distributions.

Larval Predation by Barnacles: Effects on Patch Colonization in a Shallow Subtidal Community

Laboratory studies and gut—content analysis suggest that barnacles should be important predators on invertebrate larvae. To determine if predation on larvae limits settlement, we recorded recruitment in artificially produced patches of clear substratum surrounded by monocultures of either living or dead barnacles. Living barnacles inhibited recruitment of colonial ascidians and bryozoans, but had no detectable effect on recruitment of barnacles, serpulid polychaetes, or solitary ascidians. Patch size did not influence the recruitment of any species. The presence of dead barnacle shells influenced spatial pattern of settlement in ascidians and serpulids. Comparison of blank control plates with barnacle—covered plates indicates that these spatial patterns are better explained by larval behavior than by small—scale hydrodynamic effects. Ascidians, which are dominant competitors in this community, settle primarily on shells of dead barnacles rather than on clear primary substratum. Although predation on larvae by barnacles appears to inhibit recruitment of some species, its effects are variable and easily confounded with other determinants of settlement distribution.

Structural aspects of sessile invertebrates as organizing forces in an Estuarine fouling community

The role of physical structure in the development of a fouling community in the Broadkill River Estuary, Delaware, was examined over the period March 1975 through January 1976. Asbestos cement panels and “mimic” panels were used to collect sessile fouling organisms and their motile associates. “Mimic” panels contained various objects representing the structural aspects of dead barnacles, tunicates, and hydroids. These are the dominant structural forms of early successional stages in the community. Structure provided by mimics enhanced settlement of both mussels ( Mytilus edulis L.) and tunicates ( Molgula manhattensis (DeKay)). Settlement of the hydroid Tubularia crocea (Agassiz) was unaffected by mimic structure, while colonization by barnacles ( Balanus improvisus Darwin) and serpulid polychaetes ( Hydroides dianthus Verrill) was more successful on bare surfaces than on mimic panels. These responses to structure correspond with patterns observed in the unaltered community, and which eventually determined its species composition. Balanus and Hydroides selected only bare surfaces for settlement and were earlier successional species. Molgula and Mytilus prefered previously occupied substrates, and Mytilus eventually dominated. The number of motile species on panels was positively correlated with the number of sessile species and negatively correlated with sessile species dominance. Sessile and motile diversity were causally related; this resulted from responses of motile species to structure supplied by sessile forms. More motile species were found on mimic as opposed to plain panels during early development. Physical structure supplied by sessile fouling species is an important characteristic of the system that determines habitat preferences and habitat suitability for both other sessile species and associated motile forms.

Description of a Tetraclita stalactifera panamensis community on a rocky intertidal Pacific shore of Panama

The midlittoral zone at Paitilla Beach, Panama, Is occupied by a group of organisms closely associated with Tetraclita stalactifera panamensis. Upon death, this cirripede provides housing for a number of species bound by common substrata and interacting with each other due to their close physical proximity; the faunistic group associated with each barnacle qualifies then, as a small, well-defined community which represents a subsample of the more comprehensive midlittoral community dominated by T. stalactifera panamensis. In patches where it is abundant, T. stalactifera panamensis occupies 28% of the surface area available. It has a relative abundance of only 1% of the specimens found in the zone, but all the other 95 species (with an average of 26, 810 individuals/m2) identified from the area are associated either with the parietal canals, or the external or internal surfaces of T. stalactifera panamensis tests. Each one of these structures represents a habitat which provides surface for attachment, shelter, or both, to 37 species of polychaetes, 32 of mollusks, 20 of crustaceans, 3 of actiniarians, 2 of pycogonids, 2 of sipunculans and an unknown number of tanaid, nemertean and turbellarian species. The single most diverse space-niche is represented by the parietal canals (H=0.783), occupied mostly by polychaetes. dead barnacles harbor an average of 131 individuals per test, which compose a fauna of higher diversity (H=0.678) than that associated with live barnacles (H=0.163). The latter contain 53 specimens per test on the average. Although there is considerable overlapping of species associated with the different T. stalactifera panamensis space-niches, mollusks are clearly more abundant on internal surfaces, polychaetes in parietal, canals; Balanus spp. on external surfaces, and anemones at the base of the parapet on the external surfaces of the tests. Over 220 species of macro-invertebrates were identified from the rocky intertidal at Paitilla. Most of the species are concentrated in the lower (157 species, 1824 specimens/m2) and midlittoral (96 species, 26, 810 specimens/m2) intertidal zones. Splash zone is depauperate (6 species, 1578 specimens/m2). Of the entire fauna identified from the intertidal, 73 species (33%) occur in more than one zone and 147 (67%) are restricted to a particular belt. This last category of zone-restricted species breaks down into 42% for the lower intertidal, 17% for the midlittoral, 6% for the intermediate zone, and 2% for the splash zone.

Note on the Occurrence of Arthopyrenia foveolata at Plymouth

When shore-collecting for marine algæ at Plymouth in early April, an organism which has now been identified as a calcareous lichen was brought to my notice by Dr. Orton. It occurred in large patches on the rocks both above and below high-water mark in the neighbourhood of the Marine Biological Station, and was also very frequent on the limpets and barnacles in the vicinity. When examined with a lens, the thallus of the lichen was observed to be thickly dotted either with perithecia or with well-marked pits which had apparently been previously occupied with fruits. The lichen was found to be identical with the species collected in Robin Hood Bay, Yorkshire, by E. M. Holmes, in 1901, and described by A. Lorrain Smith as Arthopyrenia foveolata. Arthopyrenia differs from Verrucaria in the fact that the associated alga is Trentepohlia, and the above species is easily distinguished by the pits which occur on the thallus.The same species has been recorded by M. C. Knowles from various places round the coast of Ireland, including the western shore of Blacksod Bay. It occurred on limestone rocks at about high neap-tide level, and also on live and dead barnacles where it was almost always associated with colonies of Rivularia atra. At Plymouth, the frequent occurrence of the lichen on limpet shells is a conspicuous feature in the distribution.