Venerid Bivalves Research Articles

Prey utilization by Neptunea arthritica (Caenogastropoda: Buccinidae): predation on gastropods and size-related variation

ABSTRACT The whelk Neptunea arthritica (Buccinidae) is a common fishery species in Hokkaido, northern Japan. Although ecological information is needed for fisheries management, there is only one paper examining the foraging ecology of this species and it reported that N. arthritica preyed mainly on the invasive mussel Mytilus galloprovincialis. To date, no studies have examined utilization of native prey species by this whelk. Here, we report the findings of a study on the native prey utilization by N. arthritica in an area where M. galloprovincialis is not present. We conducted line transect sampling every month from May 2018 to May 2019 on the western coast of Hakodate Bay, southwestern Hokkaido, Japan. Prey items were composed mostly of gastropods (72%), followed by bivalves (24%) and only a small amount of carrion (<4%). Overlapping spatial distributions were observed among size classes of N. arthritica, while the prey utilization varied with body size. Small individuals (<30 mm in shell height) preyed mainly on the small colloniid gastropod Homalopoma sangarense, while larger individuals (>40 mm) preyed mainly on two tegulid gastropods (Chlorostoma lischkei and Omphalius rusticus) and two venerid bivalves (Protothaca euglypta and Ruditapes philippinarum). There were positive size relationships between whelk body size and prey size for prey categories (Vetigastropoda, Caenogastropoda and Bivalvia) and even for the same prey species (H. sangarense, O. rusticus and P. euglypta). These results suggest that N. arthritica is a predator of mobile gastropods, especially during its early life stage, in areas without the invasive Mediterranean mussel. It is possible that the foraging strategy of N. arthritica may differ quite markedly between areas with and without the invasive mussel.

Victims of ancient hyperthermal events herald the fates of marine clades and traits under global warming.

Organismic groups vary non-randomly in their vulnerability to extinction. However, it is unclear whether the same groups are consistently vulnerable, regardless of the dominant extinction drivers, or whether certain drivers have their own distinctive and predictable victims. Given the challenges presented by anthropogenic global warming, we focus on changes in extinction selectivity trends during ancient hyperthermal events: geologically rapid episodes of global warming. Focusing on the fossil record of the last 300 million years, we identify clades and traits of marine ectotherms that were more prone to extinction under the onset of six hyperthermal events than during other times. Hyperthermals enhanced the vulnerability of marine fauna that host photosymbionts, particularly zooxanthellate corals, the reef environments they provide, and genera with actively burrowing or swimming adult life-stages. The extinction risk of larger sized fauna also increased relative to non-hyperthermal times, while genera with a poorly buffered internal physiology did not become more vulnerable on average during hyperthermals. Hyperthermal-vulnerable clades include rhynchonelliform brachiopods and bony fish, whereas resistant clades include cartilaginous fish, and ostreid and venerid bivalves. These extinction responses in the geological past mirror modern responses of these groups to warming, including range-shift magnitudes, population losses, and experimental performance under climate-related stressors. Accordingly, extinction mechanisms distinctive to rapid global warming may be indicated, including sensitivity to warming-induced seawater deoxygenation. In anticipation of modern warming-driven marine extinctions, the trends illustrated in the fossil record offer an expedient preview.

Venerid bivalve Venus verrucosa as a high-resolution archive of seawater temperature in the Mediterranean Sea

High-resolution stable isotope data (δ18O, δ13C) were used to study growth strategies of the bivalve Venus verrucosa collected from three sites of the eastern coast of the Adriatic Sea. The principal objectives of this study were to identify the main growing season and to evaluate the potential applicability of δ18Oshell values to reconstruct the seasonal temperature variability. Calcium carbonate for oxygen and carbon isotope analyses was obtained by drilling the outer shell layer. Temporal and spatial variations in temperature and salinity values at the study sites were simulated using the 3D numerical ocean model ROMS. Annual periodicity of growth patterns was confirmed by δ18Oshell cycles which corresponded to the number of observed seasonal growth marks. Temporal alignment of stable oxygen data with modelled seawater temperature data indicates that V. verrucosa deposits shell material from March/April to December. Shell growth slowdown and/or cessation occurred between late winter and early spring when the seawater temperature dropped below 12 °C at the two northern sites, Istria and Pag Bay, and below 13 °C at the southern site, Kaštela Bay. Summer temperatures reconstructed from V. verrucosa agreed well with modelled summer temperatures, but lowest reconstructed temperatures were consistently higher than the modelled winter values. The range of δ18Oshell values obtained from V. verrucosa shells is higher than the range obtained previously from other species in the eastern Adriatic Sea, indicating the high potential of V. verrucosa for temperature reconstructions.

Unorthodox features in two venerid bivalves with doubly uniparental inheritance of mitochondria

In animals, strictly maternal inheritance (SMI) of mitochondria is the rule, but one exception (doubly uniparental inheritance or DUI), marked by the transmission of sex-specific mitogenomes, has been reported in bivalves. Associated with DUI is a frequent modification of the mitochondrial cox2 gene, as well as additional sex-specific mitochondrial genes not involved in oxidative phosphorylation. With the exception of freshwater mussels (for 3 families of the order Unionida), these DUI-associated features have only been shown in few species [within Mytilidae (order Mytilida) and Veneridae (order Venerida)] because of the few complete sex-specific mitogenomes published for these orders. Here, we present the complete sex-specific mtDNAs of two recently-discovered DUI species in two families of the order Venerida, Scrobicularia plana (Semelidae) and Limecola balthica (Tellinidae). These species display the largest differences in genome size between sex-specific mitotypes in DUI species (>10 kb), as well as the highest mtDNA divergences (sometimes reaching >50%). An important in-frame insertion (>3.5 kb) in the male cox2 gene is partly responsible for the differences in genome size. The S. plana cox2 gene is the largest reported so far in the Kingdom Animalia. The mitogenomes may be carrying sex-specific genes, indicating that general mitochondrial features are shared among DUI species.

Macrobenthic community associated with semi-cultured blood cockles (Tegillarca granosa) in tropical mudflats

This study aims to address the potential effects of environmental factors, competition and predation among cohabiting macrobenthos, and in particular on the cultured blood cockles (Tegillarca granosa). Macrobenthos and environmental variables were sampled from culture beds close to the harvesting period at two sites (BNO, BSB) in Selangor and one (KSB) in Perak (Malaysia). A total of 79 taxa were recorded mostly belonging to three taxonomic groups, Mollusca (27 taxa), Crustacea (26) and Actinopterygii (18). Redundancy analysis revealed close associations among the common scavenging/grazing gastropods (Nassarius bellulus and N. jacksonianus), predatory gastropods (Notocochlis tigrina and Indothais malayensis) and various macrobenthic species suggesting competition and predation risk to the cultured bivalves. The biomass of sediment chlorophyll-a (highest at BNO) was correlated with higher T. granosa and macrobenthic density. The higher ammonia level at BSB and KSB may explain the lower macrobenthic density and reduced competition allowing the venerid bivalve, Pelecyora cf. gouldii to proliferate at the expense of T. granosa. This study identified two abiotic factors (nutrient enrichment, ammonia) and two biotic factors (food limitation and predation) that potentially affect the production of densely-stocked T. granosa on the mudflat.

Behavioral responses of three venerid bivalves to fluctuating salinity stress

The link between the behavior of organisms living within the sediment and benthic-pelagic coupling is critical to our interpretation of impacts of physiological stress. The rapidity with which organisms respond to a stress and recover once a stress is removed impacts the cascade of secondary effects that result from such behavioral changes. Such behavioral responses, although critical to our understanding, are difficult to quantify, particularly for organisms such as bivalves that inhabit sediments, the most common spatial habitat on Earth. Sublethal responses to fluctuating stressors such as salinity are rarely quantified in terms of activity. Here we do so using a combination of direct observations and pressure sensors, which allow us to record burrowing and other hydraulic activities. Based on our field observations and the literature, we predicted that there would be a breakpoint in behavior between salinities of 15 and 20 and that below this breakpoint the animals would significantly reduce activities including burrowing and feeding. The data presented support this prediction; burrowing was reduced in all three species at salinities at or below 15 as were fecal deposition and appearance of siphons above the sediment surface. These data are consistent with the prediction that under conditions of large fluctuations in salinity the magnitude of the link to primary productivity and nutrient availability from the benthos will be significantly reduced.

PALEOGEOGRAPHIC NORTHEASTERN LIMITS OF APHRODINA DUTRUGEI (COCQUAND, 1862) (HETERODONTA, BIVALVIA) FROM THE CENOMANIAN OF THE ARABIAN PLATFORM

The finding of Aphrodina dutrugei (Cocquand, 1862) in a rich collection of non-rudist bivalve fauna from the famous Cenomanian-Turonian carbonates of the Afro-Arabian Plate has permitted the reevaluation of venerid bivalves during an important period of their evolution. The genus Aphrodina Conrad, 1869, Family Veneridae Rafinesque, 1815, embraces several Tethyan Cretaceous species that range from Cenomanian to Santonian. During the late Albian-Maastrichtian ‘Aphrodiniid’ venerids, were distributed along the western margin of the Atlantic (North and South America), the Afro-Arabian Plate (Jordan, SE Turkey, Morocco, Algeria and Egypt), the eastern Tethys, and the Southern Ocean (India, Japan, western Australia and New Zealand). They are also known in the Turonian-Santonian Trans-Saharan Seaway (Gabon). Until now these fossils have been unknown in any Upper Cretaceous localities of southeastern Turkey. In this paper, we report the first record of one of the most common and widespread shallow infaunal species, Aphrodina dutrugei, in the Cenomanian Derdere Formation in the Mardin-Mazidagi area, SE Turkey, which is in the extreme northeastern part of its known range.

Exploitation status and stock assessment of the smooth clam Callista chione (Linnaeus, 1758) in the northern Alboran Sea (GSA01-W Mediterranean Sea)

The smooth clam, Callista chione (Linnaeus, 1758), is a venerid bivalve widely appreciated in southern Spain where it represents the top commercial bivalve species in terms of landings and economic value. In this area, a total of 223 artisanal boats (68% of the artisanal fleet) are involved in shellfishing targeting bivalve molluscs, including the smooth clam. The artisanal mechanised dredging that targets C. chione in the northern Alboran Sea is described and the current exploitation status of its populations is analysed. A surplus-production model was run using ASPIC and used to assess the temporal variation in the levels of fishing for this bivalve throughout the study period (2002-2015), as well as to suggest conservation reference points that could guarantee the sustainable exploitation of this resource. During the study period, the maximum C. chione catch was registered in 2003 (306 t) and the minimum in 2006 (93 t). The ASPIC model for C. chione stock suggests that a Maximum Sustainable Yield (MSY) of 216 t could be produced from a total stock biomass of 983 t (Bmsy) at a fishing mortality rate of total biomass of 0.22 (Fmsy), with B/Bmsy and F/Fmsy values of 1.34 and 0.82, respectively, indicating that the stock is approaching good status.

The complete mitochondrial genome of the grooved carpet shell, Ruditapes decussatus (Bivalvia, Veneridae).

Despite the large number of animal complete mitochondrial genomes currently available in public databases, knowledge about mitochondrial genomics in invertebrates is uneven. This paper reports, for the first time, the complete mitochondrial genome of the grooved carpet shell, Ruditapes decussatus, also known as the European clam. Ruditapes decussatus is morphologically and ecologically similar to the Manila clam Ruditapes philippinarum, which has been recently introduced for aquaculture in the very same habitats of Ruditapes decussatus, and that is replacing the native species. Currently the production of the European clam is almost insignificant, nonetheless it is considered a high value product, and therefore it is an economically important species, especially in Portugal, Spain and Italy. In this work we: (i) assembled Ruditapes decussatus mitochondrial genome from RNA-Seq data, and validated it by Sanger sequencing; (ii) analyzed and characterized the Ruditapes decussatus mitochondrial genome, comparing its features with those of other venerid bivalves; (iii) assessed mitochondrial sequence polymorphism (SP) and copy number variation (CNV) of tandem repeats across 26 samples. Despite using high-throughput approaches we did not find evidence for the presence of two sex-linked mitochondrial genomes, typical of the doubly uniparental inheritance of mitochondria, a phenomenon known in ∼100 bivalve species. According to our analyses, Ruditapes decussatus is more genetically similar to species of the Genus Paphia than to the congeneric Ruditapes philippinarum, a finding that bolsters the already-proposed need of a taxonomic revision. We also found a quite low genetic variability across the examined samples, with few SPs and little variability of the sequences flanking the control region (Largest Unassigned Regions (LURs). Strikingly, although we found low nucleotide variability along the entire mitochondrial genome, we observed high levels of length polymorphism in the LUR due to CNV of tandem repeats, and even a LUR length heteroplasmy in two samples. It is not clear if the lack of genetic variability in the mitochondrial genome of Ruditapes decussatus is a cause or an effect of the ongoing replacement of Ruditapes decussatus with the invasive Ruditapes philippinarum, and more analyses, especially on nuclear sequences, are required to assess this point.

The stratigraphic architecture and depositional environments of non-marine carbonates from barremian-aptian pre-salt strata of the Brazilian continental margin

The stratigraphic architecture and depositional environments of non-marine carbonates from barremian-aptian pre-salt strata of the Brazilian continental margin

Impacts of Sublethal and Lethal High Temperatures on Clams Exploited in European Fisheries

ABSTRACT In Galicia, three venerid bivalves are exploited in the intertidal zone by local fishery guilds: Venerupis corrugata, Ruditapes philippinarum, and Ruditapes decussatus. The precise effects of the duration and intensity of high-temperature episodes on these bivalves remain largely unknown, especially when the animals are in sediment which acts as a thermal buffer. Clams in sediment were exposed to recorded summer sediment temperatures: 21°C(control), 27°C, 32°C, and 36°C(measured at 2 cmdepth in the sediment) on the diurnal low tide during three consecutive days. Burrowing activity of R. decussatus relative to temperature was a negative quadratic response, typical of performance curves where the upper limit to activity has been exceeded. The venerid bivalve V. corrugata showed evidence of sublethal stress with reduction in burrowing activity, starting at 27°C. Temperatures greater than 32°C are common on days with hot low tides on clam fisheries grounds in Galicia and are expected to increase in f...

Underwater observations of the giant spoon worm Ikeda taenioides (Annelida: Echiura: Ikedidae) in a subtidal soft-bottom environment in northeastern Japan, which survived tsunamis of the 2011 off the Pacific Coast of Tohoku Earthquake

Tsunamis associated with the 2011 off the Pacific Coast of Tohoku Earthquake seriously disrupted the shallow marine ecosystem along a 2000 km stretch of the Pacific coast of Japan. The effects of the 2011 tsunamis on the soft-bottom benthic community have been relatively well studied in the intertidal zone, whereas tsunami effects on the subtidal benthos remain poorly understood. Here, we investigated populations of the world’s largest spoon worm Ikeda taenioides (Annelida: Echiura: Ikedidae) in subtidal zone of Funakoshi Bay, Tohoku District, northeastern Japan. Subtidal scuba-diving surveys at two sites in the bay showed extremely long proboscises frequently extending from small holes in the sandy seafloor shortly before and soon after the tsunami disturbances. Based on morphological and molecular identification, the proboscises were revealed to be parts of I. taenioides. On 30 November 2011, 265 days after the tsunami event, many large-sized individuals with >1 m long proboscises were observed; these individuals were probably not derived from post-tsunami larval recruitment but more likely survived the tsunami disturbances. This is surprising because other sympatric megabenthos (e.g. spatangoid echinoids and venerid bivalves) and seagrass beds were almost completely destroyed (although they later recovered) by the tsunamis in this bay. The burrows of I. taenioides are known to be very deep (70–90 cm), which may have sheltered them from the impacts of the tsunamis. Our observations suggest that the effects of the 2011 tsunamis on benthos in soft sediments may differ depending on their burrowing depth.

Geological setting, sedimentology and biota of the estuarine late Oligocene Pomahaka Formation, New Zealand

ABSTRACTPomahaka Formation, a late Oligocene succession of interbedded mudstone, lignite, shell beds and thin sands, was studied in small exposures along the Pomahaka River near Tapanui, Otago and in four adjacent sections in Waikoikoi Creek where about 17 × 0.25–4.0 m thick facies cycles were exposed. At the base of an ‘ideal’ cycle, thinly laminated sandy mudstone overlying lignite of the previous cycle records transgressive flooding of forest swamp by fresh or estuarine waters. Laminated shelly mudstone containing venerid bivalves (Hinemoana acuminata) forming the middle of several cycles represents maximum marine flooding. Above this, trough cross-stratified beds and sand with mud flaser laminae record progradation of distributary bars and/or intertidal sands. Finally, deposition of root-burrowed mudstone and lignite mark the re-establishment of swamp forest. Predominantly muddy sediment texture, the association of lignite, distinctive fresh- and brackish-water faunas and thin depositional cycles indicate a microtidal estuarine paleo-environment in southern Zealandia during late Oligocene time.

NEW RECORDS OF VENERID BIVALVES (BIVALVIA: VENERIDAE) AT SIDOARJO COASTAL WATER, INDONESIA

<p>The occurrence of two venerid bivalves, Timoclea (Chioneryx) scabra (Hanley) and Clamentia vatneleti Mabille, in coastal water of Sidoarjo, East Java, Indonesia is reported. They are described and illustrated based on the local specimens collected. Based on available published materials, these two species collected are new records at Sidoarjo Coastal water.</p><p><strong>Keywords</strong>: Timoclea (Chioneryx) scabra, Clamentia vatneleti, Veneridae, Sidoarjo.</p>

Two alien venerid bivalves from the Eastern Mediterranean

We report the first record in the Mediterranean Sea of the minute Indo-Pacific venerid bivalveCostellipitar chordatum. The species has recently established a small population off the central coast of Israel. Numerous live specimens ofGouldiopa consternans, at several locations off the Israeli coast, confirm the presence of a fast growing population. This is the first record of the species from Israel, following a recent report from Turkey.

Variation in Population Structure and Density ofAustrovenus stutchburyi(Veneridae) from Canterbury, New Zealand

ABSTRACT Worldwide, shellfish beds are declining and are threatened by anthropogenic changes. Although the little neck clam Austrovenus stutchburyi supports commercial harvesting, little is known about the population status of this burrowing venerid bivalve in many parts of New Zealand. Populations were sampled seasonally (4 times each year) for 3 y and then during the summer for an additional 4 y within 4 estuarine systems in the Canterbury region of South Island. The aim was to determine population density and class size composition, comparing high-salinity and low-salinity sites with a range of contaminant inputs. The data presented cover pre- and postearthquake events (earthquake sequence commenced on September 4, 2010). Our results show both temporal and spatial variation in population size with irregular recruitment success (0–70 juveniles/m2) across all sites. Density (range, 100–3,500 clams/m2) and mean clam length (range, 17.4–31.6 mm) did not correlate with salinity, sediment trace metal concent...

Spermcasting of spermatozeugmata by the bivalvesNutricola confusaandN. tantilla

The dynamics and consequences of the varied reproductive modes of marine invertebrates is a rich and vibrant field of inquiry for ecological and evolutionary studies. One mode of reproduction that is not as well-studied as others is “spermcasting” or “spermcast mating,” when males broadcast sperm and females retain eggs and brood developing embryonic stages. This type of reproduction occurs in two small (maximum adult shell length ~5–6 mm) venerid bivalves, Nutricola confusa and N. tantilla, that live in protected bays of the temperate eastern Pacific. Females of these species brood developing embryos in chambers formed by the inner demibranchs, and release fully formed juveniles. We discovered that upon exposing clams to fluvoxamine, a selective serotonin reuptake inhibitor, males release spermatozeugmata, clusters of sperm cells attached by their heads to a central core. Spermatozoa of Nutricola have unusually long, needle-shaped heads that are approximately one quarter of the total length of the cell. These heads are curled and “packaged” into the hemispherical-shaped cores of spermatozeugmata. The cores are about one-third as long as the heads, and the tails protrude out of the opposite side of the cap of the core. The spermatozeugmata display two different swimming patterns, one where the tails beat in synchrony, and the other where they do not. The size of the cores is not significantly different in the two species, but spermatozeugmata of N. tantilla have significantly longer and wider tails than those of N. confusa. Advantages to spermcasting spermatozeugmata instead of individual spermatozoa may include enhanced dispersal and increased probabilities of fertilization. One consequence of spermatozeugmata (rather than individual spermatozoa) entering female brood chambers might be lowering of the effective population size. For species like these, which lack pelagic larvae, spermatozeugmata could increase dispersal and gene flow.

Needles and pins: acicular crystalline periostracal calcification in venerid bivalves (Bivalvia: Veneridae)

A scanning electron microscope study of the periostracum of 50 species of venerid bivalves revealed that periostracal calcification in the form of aragonitic needles and shorter pins is widespread within the family. Together with organic and sediment coatings that are found in some species, these needles form an integral part of the functional shell. Visible as a white ‘crust’ on the outside of shells, long slender needles (up to 400 mm long and 1 mm wide) without adherent material are seen in species of Tivela and Lioconcha and in Gomphina undulosa. Other venerids including Pitar species, Mysia undata and Compsomyax subdiaphana have short pins, capped with a fibrous organic matrix and significant coatings of sediment. Callocardia hungerfordi and Clementia papyracea have very thick sediment coatings underlain by short pins, while Gafrarium and Circe species have short pins with a thin, robust, organic coating and little particulate material. Finally, there are species, including Venus verrucosa, Chione elevata and Mercenaria mercenaria, where minute, ,1 mm long pins also underpin a thin organic coating. Details of formation were studied in Tivela lamyi and Lioconcha ornata, where the needles are elongate hexagonal crystals of aragonite enveloped by an organic sheath, which grow at their proximal ends from within the periostracum, connected to the outer mantle epithelium via narrow channels. Growth of needles ceases following the onset of shell calcification. The distribution of the periostracal structures was examined in relation to a published molecular phylogeny that recognized two major clades within the family. Larger needles and pins are confined to the clade that includes subfamilies Pitarinae, Gouldinae, Meretricinae and Petricolinae, while submicron-sized pins are found only in the Venerinae and Chioninae of the second clade. Calcified periostracal structures appear to be absent in Tapetinae and Dosiniinae.

Age determination and growth rate of a Callista chione population from the southwestern coast of Portugal

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 5:97-106 (2009) - DOI: https://doi.org/10.3354/ab00119 Age determination and growth rate of a Callista chione population from the southwestern coast of Portugal Paula Moura, Miguel B. Gaspar*, Carlos C. Monteiro Instituto Nacional de Recursos Biológicos (INRB, I.P.) / IPIMAR, Avenida 5 de Outubro s/n, 8700-305 Olhão, Portugal *Corresponding author. Email: mbgaspar@cripsul.ipimar.pt ABSTRACT: The age and growth of the smooth clam Callista chione from the southwestern coast of Portugal were estimated during a 1 yr study period by using both the surface growth rings and internal shell microgrowth lines (by acetate peel method). The von Bertalanffy growth curves obtained by these 2 methods were, respectively: Lt = 91.9[1 – e–0.18 (t+0.22)] and Lt = 98.1[1 – e–0.15 (t+0.43)]. Based on these, the counting of surface growth rings is appropriate for a quick age estimation of individuals up to 10 yr old (~75 mm shell length, SL). For older specimens, analysis of the growth lines in the cross section of shells is recommended, because close to the shell border it becomes difficult to distinguish growth rings on the shell surface. Rapid shell growth occurred in spring and summer, whereas slow growth occurred during autumn and winter, with the deposition of an annual growth ring. The overall growth performance and the phi-prime index were used to compare growth parameters with data from literature about venerid bivalves. These parameters indicated that Callista spp. have a higher growth performance than other venerid bivalves and this is correlated with geographical latitude. The smooth clam achieves sexual maturation at 4 yr of age and reaches the minimum landing size (60 mm SL) after 5 yr. KEY WORDS: Callista chione · Smooth clam · Age · Growth rate · Growth performance · Surface rings · Acetate peel · Portugal Full text in pdf format PreviousCite this article as: Moura P, Gaspar MB, Monteiro CC (2009) Age determination and growth rate of a Callista chione population from the southwestern coast of Portugal. Aquat Biol 5:97-106. https://doi.org/10.3354/ab00119 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 5, No. 1. Online publication date: February 24, 2009 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2009 Inter-Research.

Population Growth of the Venerid Bivalve Circenita callipyga in the Hendijan Coast, Persian Gulf

Length-frequency and growth of dominant species, Circenita callipyga (Bivalve, Veneridae) in the Hendijan coast, Khuzestan province (Persian Gulf) were studied from summer 2005 to spring 2006. Sampling was done seasonally with vanveen grab from 5 stations. Stations were located 0.5 mile apart and samples were collected from approximately 8 m depth. The population structure presented a size range between 0.5 and 9.5 mm length, being mainly formed by individuals from 3 to 4 mm, that were dominant in autumn. Recruitment rate was low and the major contribution of recruits was found in winter to spring. Growth parameters of the Von Bertalanffy growth function were estimated to be Linfinity = 25.06 mm, k = 0.180 year(-1), t0 = 0.11 year.