Anadara Tuberculosa Research Articles

Prospective biomonitor and sentinel bivalve species for pollution monitoring and ecosystem health disturbance assessment in mangrove–lined Nicaraguan coasts

This research aims at contributing to the use of Polymesoda arctata, Anadara tuberculosa, and Larkinia grandis as prospective biomonitors and sentinels, surrogate of Crassostrea rhizophorae for pollution biomonitoring in mangrove-lined coastal systems. Localities were selected along the Nicaraguan coastline in the rainy and dry seasons during 2012–2013: A. tuberculosa and L. grandis were collected in the Pacific, and P. arctata in the Caribbean. The tissue concentration of metals, polycyclic aromatic hydrocarbons (PAHs) and persistent organic pollutants (POPs) were integrated into pollution indices (chemical pollution index -CPI- and pollution load index -PLI-) and biological endpoints (flesh-condition, reproduction, histopathology and stress-on-stress) were determined as biomarkers of ecosystem health disturbance. In the Caribbean, contaminant tissue concentration was low in P. arctata, with some exceptions. Ag, As, Cd, Hg, Ni and V were mainly recorded during dry season, and PAHs and POPs (HCHs, DDTs, AHTN, PCBs and BDE85) during rainy season. Metals and PAHs were not a major threat in the study area; in contrast, high levels of HCHs and DDTs and low-to-moderate levels of musk fragrances and PBDEs were recorded. Minor differences were found in biological parameters albeit during the rainy season the LT50 values were low and seemingly associated to high PLI and CPI values. In the Pacific, the main pollutants recorded in A. tuberculosa and L. grandis were HCHs, DDTs, AHTN and PDBEs in rainy season and Cd in dry season. Although basic research is needed to understand the general biology, ecology and diseases in these Pacific species, biological endpoints comparable to those used in other sentinel bivalves are seemingly suitable biomarkers of health disturbance. Overall, Caribbean P. arctata and Pacific A. tuberculosa and L. grandis seem to be potential target species for pollution monitoring and ecosystem health disturbance assessment in mangrove–lined Nicaraguan coastal systems. Their use together with C. rhizophorae would provide opportunities for common approaches to be applied in inter-ocean countries of the Mesoamerican region.

Physiological and molecular response of Anadara tuberculosa (Arcoida: Arcidae) to salinity stress.

The pustulose ark A. tuberculosa is an emblematic species of mangrove ecosystem that is currently in a vulnerable condition. The development of its aquaculture, to begin with genetic breeding programs, requires the identification of molecular biomarkers, particularly those associated with salinity stress. With this purpose, specimens of A. tuberculosa were collected from the adjacent mangroves of Puerto Pizarro bay (Tumbes, Peru), from January 2015 to February 2016. Different assays (groups of ten animals in triplicate) were undertaken in separated periods of 16 days: hypo-osmotic stress (extreme: 5, 10 ppt); (Moderate: 15, 25 ppt) and no stress (control group: 33 ppt). The presence of salinity stress biomarkers was assessed at the genetic level throughout PCR detection of 19 genes reported to be key actors in osmoregulation, and at the proteomic level with the sequencing of peptides (tandem mass spectrometry MALDI TOF/TOF), expressed in ark tissues exposed to different salinities. None of the tested genetic markers could be amplified by PCR, suggesting that A. tuberculosa has significant genetic differences compared to other mollusks. Proteomic analysis by mass spectrometry on A. tuberculosa gill tissue, allowed to identify 26 peptides expressed in presential and differential forms at different salinities, highlighting possible markers such as HSP70 and trans-membrane chloride channel transportation protein, to be related with salinity adaptation. These amino acid sequences will allow the design of target specific primers for A. tuberculosa, to implement future research in ecophysiology of this important fishery resource.

Effect of mixed-Bacillus spp isolated from pustulose ark Anadara tuberculosa on growth, survival, viral prevalence and immune-related gene expression in shrimp Litopenaeus vannamei

The widespread overuse of antibiotics in aquaculture has led to the emergence of antibiotic-resistance shrimp pathogens, the negative impact on shrimp gut microbiota, and the presence of antimicrobial residues in aquaculture products, with negative consequences on human health. Alternatively, probiotics have positive effects on immunological responses and productive performance of aquatic animals. In this study, three probiotic bacteria, (Bacillus licheniformis MAt32, B. subtilis MAt43 and B. subtilis subsp. subtilis GAtB1), isolated from the Anadara tuberculosa were included in diets for juvenile shrimp, Litopenaeus vannamei, to evaluate their effects on growth, survival, disease prevalence, and immune-related gene expression. Shrimp naturally infected with WSSV and IHHNV were fed with the basal diet (control, T1) and diets supplemented with four levels of bacilli probiotic mix (1:1:1) at final concentration of (T2) 1 × 106, (T3) 2 × 106, (T4) 4 × 106, and (T5) 6 × 106 CFU g−1 of feed. The specific growth rate of shrimp was significantly higher in T2 than in T1 (control) treatment, and the final growth as well as the survival were similar among treated groups. The prevalence of WSSV and IHHNV infected shrimp was reduced in T2 and T4 treatments, respectively, compared with control. The mRNA expression of proPO gene was higher in treatment T4 than control. The LvToll1 gene was significantly up-regulated in treatments T4 and T5 compared to control. The SOD gene was up-regulated in treatment T5 compared to control. In contrast, the mRNA expression of the Hsp70 gene was down-regulated in treatments T4 and T5 respect to control, and the TGase gene remained unaffected by the level of bacillus probiotic mix. As conclusion, the bacilli probiotic mix (Bacillus spp.) enhanced immune-related gene expression in WSSV and IHHNV naturally infected shrimp. This is the first report of probiotic potential of bacteria isolated from A. tuberculosa on the immune response and viral prevalence in shrimp Litopenaeus vannamei.

Estimación de la diversidad genética de Anadara tuberculosa en cinco manglares de Tumaco, utilizando la enzima citocromo oxidasa I

RESUMENObjetivo. Estimar la diversidad genética de Anadara tuberculosa en cinco manglares de Tumaco Nariño, Colombia utilizando como marcador molecular mitocondrial la subunidad I de la citocromo oxidasa (COI). Materiales y métodos. Se colectaron en total 50 individuos de los manglares San Jorge, La Tiburonera, El Pajal, La Playa y Bajito Vaquería, tomando 10 ejemplares al azar de cada extrajo y amplificó el ADN mitocondrial mediante la técnica de PCR (Polymerase Chain Reaction). Los productos de PCR amplificados y cuantificados se secuenciaron por ambos lados (Macrogen). Una vez se obtuvo las secuencias, se editó y alineo cada secuencia. Posteriormente, se midió los parámetros de diversidad genética (haplotípica y nucleotídica) y se elaboró el análisis de distribución entre pares de frecuencias (Mistmach distribution). Finalmente se efectuó el análisis de variación nucleotídica y la estructura poblacional (AMOVA). Resultados. El gen amplificado tuvo una longitud de 710 pb. La diversidad haplotípica reportada para todas las poblaciones fue alta (0.683±0.060) y la diversidad nucleotídica reportada fue baja para todas las poblaciones (0.040±0.020). Los resultados del AMOVA indican que la varianza entre poblaciones es baja (4.20%) y la varianza dentro de las poblaciones es alta (95.80%). Conclusiones. Las poblaciones estudiadas no se encuentran estructuradas y a pesar de la disminución de los bancos naturales de las poblaciones de Anadara tuberculosa, se estima que la diversidad genética es alta.

Bacteriological study of bivalves from the Gulf of Nicoya, Costa Rica. I. Condition of the mollusk recently collected

During the first six months of 1970 we collected 16 lots of the bivalve Anadara tuberculosa from two areas within the Gulf of Nicoya, Costa Rica. These were examined bacteriologically and the coliform levels found in all of them were such that they had to be graded as not satisfactory for human consumption, according to generally accepted norms. The source of these coliforms is attributed to the sewage discharge of the city of Puntarenas into its estuary.

ESTADO DE LA POBLACIÓN Y VALORACIÓN DE ALGUNAS ESTRATEGIAS DE CONSERVACIÓN DEL RECURSO PIANGUA ANADARA TUBERCULOSA (SOWERBY) EN SECTORES DE BAZÁN Y NERETE, COSTA PACÍFICA NARIÑENSE DE COLOMBIA

The objective of this investigation was to evaluate the status of piangua (Anadara tuberculosa, Sowerby) populations in two areas of the province of Nariño (Pacific coast of Colombia), and to assess the effect on natural communities of conservation strategies such as closed periods, rotation on extracting areas, and enforcement of the 5 cm minimum size declared by INPA (resolution 539, 2000). Permanent plots were set up and all piangua were collected using the traditional manual techniques. Morphometric measurements of gathered organisms were recorded. Subsequent samplings were performed at different times depending on the conservation strategy evaluated. A total of 10441 individuals of A. tuberculosa were collected, 61 % corresponding to Bazán and 39 % to Nerete. All conservation strategies assessed showed positive effects on the conservation and sustainable use of the resource, being closed periods of two months the one with better results (p= 0.027 for Bazán and p= 8.57E-06 for Nerete; Tukey: p< 0.05); in Bazán, this strategy was the only one showing positive results, while in Nerete the three strategies showed to be effective.

Isolation and characterization of potential probiotic bacteria from pustulose ark (Anadara tuberculosa) suitable for shrimp farming

In aquaculture, probiotics have been tested for enhancing the immune system and promoting growth and survival rate of many marine species like shrimp and mollusks. In order to isolate bacteria with a high probiotic potential for marine shellfish aquaculture, homogenates of the gastrointestinal tract from adult mangrove cockle, Anadara tuberculosa , were obtained to perform in vitro and in vivo assays. Isolates were tested in vitro for hemolytic activity, hydrophobicity, tolerance to ammonia nitrogen, salinity and pH as well as for growth kinetics, extracellular enzymatic activity, autoaggregation, coaggregation and molecular identification. Three bacteria with high degree of hydrophobicity (>60% adherence to p-xylene) and four bacteria with medium hydrophobicity, which showed different patterns of attachment to monopolar solvents (chloroform and ethyl acetate) and a high tolerance to ammonia nitrogen (200 mg L -1 ), were selected. Six different treatments: T1 (without addition of cultured bacteria); T2 (MAt29, Enterococcus casseliflavus ); T3 (MAt35, Citrobacter koseri ); T4 (GAtB1, Bacillus subtilis subtilis ); T5 (GAt7, Staphylococcus sp.); and T6 (1:1:1:1 mix of strains T2, T3, T4 and T5), were used to evaluate the specific growth rate, and cellular immune response of the shrimp Litopenaeus vannamei . The best specific growth rate was observed for T6 and T4 treatments related to Bacillus subtilis subtilis . A significant difference in total hemocytes count ( P < 0.05) was found for T4 treatment with respect to control group. Strains isolated from A. tuberculosa had a beneficial effect on the growth and immune response of L. vannamei , so they have potential use as probiotics in aquaculture of marine shellfish.

Variaciones en la historia de vida de Anadara tuberculosa (Mollusca: Bivalvia) en el ecosistema de manglar de la costa Sur de Ecuador

Anadara tuberculosa is one of the most important bivalves along the Western Pacific coast because of its commercial value. Nevertheless, the variability in growth, long-life span, natural mortality and reproductive parameters of this mangrove cockle has not yet been described. The aim of this study was to analyze these life-history traits in three areas of the Southern coast of Ecuador. Empirical and length-based methods were used to estimate these biological parameters. Body size data were collected from the commercial fishery between 2004 and 2011 in landing ports near to the Archipelago of Jambeli [Puerto Bolivar (PB), Puerto Jeli (PJ) and Puerto Hualtaco (PH)]. The von Bertalanffy growth parameters for combined sex were estimated between 70.87 to 93.45mm for L(infinity) and 0.22 to 0.80/year for k. The growth indices (PHI') ranged from 3.17 to 3.85, while the overall growth performance (OGP) ranged from 5.03 to 5.82. The mean of long-life span (t(max)), size and age at maturity (L50% and t50%) were estimated in 7.71 +/- 2.53 years, 39.13 +/- 2.24mm and 1.46 +/- 0.56 years for PB; 9.51 +/- 2.85 years, 37.78 +/- 1.95mm and 1.37 +/- 0.41 years for PJ and 5.81 +/- 2.11 years, 39.73 +/- 3.31mm and 0.94 +/- 0.41 years for PH. Natural mortality (M) ranged from 0.46 to 1.28/year. We concluded that significant intra-specific variation was observed in a temporal scale in PHI' and OGP indices as well as L50% and M. Therefore, temporal changes in these life-history traits should be taken into account when assessing the status of the mangrove cockle fishery.

Bioaccumulation of naphthalene and fluoranthene in the bivalve mollusc Anadara tuberculosa (Sowerby, 1833)

The bioaccumulation of naphthalene and fluoranthene in the bivalve Anadara tuberculosa, was followed through the development of semistatic tests and exposure of organisms in individual tests for each compound at a concentration of 0.1mg/g for a period of 30 days. The highest level of naphthalene accumulated by the organisms reached 3.42mg/g after 15 days of exposure, while the lowest recorded concentration was presented after 20 days of test with 1.57 mg/g. For fluoranthene the initial concentration in organisms, when starting the trial was 5.88 mg/g and after exposure to the compound in the middle of the concentrations levels between 194.77mg/g for 5 days of testing and 1011.30mg/g for day 25 were registered. Fluctuations in terms of accumulation and purification of the compounds show a greater stability and incorporation of fluoranthene compared to naphthalene, which is related to the properties of each compound, especially those related to molecular weight and hydrophobicity.

Shifting policies, access, and the tragedy of enclosures in Ecuadorian mangrove fisheries: towards a political ecology of the commons

After decades of mangrove deforestation for the development of shrimp farming, the Ecuadorian state began to officially recognize the ancestral rights of traditional users of coastal mangrove resources in the late 1990s. This article traces the trajectory of coastal policy change and the transformation of mangrove tenure regimes from an implicit preference for shrimp aquaculture to a focus on conservation and sustainable development with greater community participation through the establishment of community-managed mangrove areas called custodias. I argue that while the custodias have empowered local communities in their struggle to defend their livelihoods and environment against the marginalizing forces of global shrimp aquaculture, the implementation of common property arrangements for mangrove fishery management has changed the nature of property rights, the distribution of resources, and social relations among collectors of mangrove cockles (Anadara tuberculosa and A. similis). I suggest a need to develop a political ecology of the commons, an analytical approach applied here to examine the fundamental shift in the nature of the struggle over mangrove resources, from artisanal fishers versus shrimp farmers to a struggle between compañeros: members of associations versus independent cockle collectors. Such a shift in the struggle over resources threatens to undermine the sustainability of the fishery. I conclude that shifting access may be an important underlying factor contributing to a tragedy of enclosures in Ecuador's mangrove cockle fishery.Keywords: political ecology; property rights; common property; access; tragedy of enclosures; shrimp aquaculture; mangroves; artisanal fisheries; Anadara spp., Ecuador

Comparative bioaccumulation of trace metals using six filter feeder organisms in a coastal lagoon ecosystem (of the central-east Gulf of California)

The Tobari Lagoon, located in the central-east coast of the Gulf of California, receives effluents from the Yaqui Valley, one of the most extensive agricultural areas of México. The Tobari Lagoon also receives effluents from nearby shrimp farms and untreated municipal sewage. Surface sediment samples and six different species of filter feeders (Crassostrea corteziensis, Crassostrea gigas, Chione gnidia, Anadara tuberculosa, Chione fluctifraga, and Fistulobalanus dentivarians) were collected during the dry and the rainy seasons and analyzed to determine concentrations of cadmium (Cd), copper (Cu), mercury (Hg), lead (Pb), and zinc (Zn). Seasonal variations in metal concentrations in sediment were evident, especially for Cd, Cu, Hg, and Zn. The total and bioavailable concentrations of the five metals are not elevated in comparison to other areas around the world. The percentages of bioavailable respect to total concentrations of the metals varied from 0.6 % in Hg to 50.2 % for Cu. In the organisms, Hg showed the lowest concentrations (ranged from 0.22 to 0.65 μg/g) while Zn showed the highest (ranged from 36.6 to 1,702 μg/g). Linear correlations between the levels of Cu, Pb, and Zn in the soft tissues of C. fluctifraga and C. gnidia, and A. tuberculosa and C. gnidia were found. Seasonal and interspecies variations in the metal levels in filter feeders were found; F. dentivarians, C. corteziensis, and C. gigas exhibited the highest levels, could be used as biomonitors of metals contamination in this area.

Cockles in custody: the role of common property arrangements in the ecological sustainability of mangrove Fisheries on the Ecuadorian Coast

Scholars of common property resource theory (CPR) have long asserted that certain kinds of institutional arrangements based on collective action result in successful environmental stewardship, but feedback and the direct link between social and ecological systems remains poorly understood. This paper investigates how common property institutional arrangements contribute to sustainable mangrove fisheries in coastal Ecuador, focusing on the fishery for the mangrove cockle ( Anadara tuberculosa and A. similis ), a bivalve mollusk harvested from the roots of mangrove trees and of particular social, economic, and cultural importance for the communities that depend on it. Specifically, this study examines the emergence of new civil society institutions within the historical context of extensive mangrove deforestation for the expansion of shrimp farming, policy changes in the late 1990s that recognized “ancestral” rights of local communities to mangrove resources, and how custodias, community-managed mangrove concessions, affect the cockle fishery. Findings from interviews with shell collectors and analysis of catch-per-unit-effort (CPUE) indicate that mangrove concessions as common property regimes promote community empowerment, local autonomy over resources, mangrove conservation and recovery, higher cockle catch shares, and larger shell sizes, but the benefits are not evenly distributed. Associations without custodias and independent cockle collectors feel further marginalized by the loss of gathering grounds, potentially deflecting problems of overexploitation to “open-access” areas, in which mangrove fisheries are weakly managed by the State. Using Ostrom’s Institutional Analysis and Development (IAD) framework, the explicit link between social and ecological systems is studied at different levels, examining the relationship between collective action and the environment through quantitative approaches at the fishery level and qualitative analysis at the level of the mangrove landscape. Implications for coastal and fishery management are discussed in the conclusions.

Cockles in custody: the role of common property arrangements in the ecological sustainability of mangrove Fisheries on the Ecuadorian Coast

Scholars of common property resource theory (CPR) have long asserted that certain kinds of institutional arrangements based on collective action result in successful environmental stewardship, but feedback and the direct link between social and ecological systems remains poorly understood. This paper investigates how common property institutional arrangements contribute to sustainable mangrove fisheries in coastal Ecuador, focusing on the fishery for the mangrove cockle (<em>Anadara tuberculosa</em> and <em>A. similis</em>), a bivalve mollusk harvested from the roots of mangrove trees and of particular social, economic, and cultural importance for the communities that depend on it. Specifically, this study examines the emergence of new civil society institutions within the historical context of extensive mangrove deforestation for the expansion of shrimp farming, policy changes in the late 1990s that recognized “ancestral” rights of local communities to mangrove resources, and how <em>custodias, </em>community-managed mangrove concessions, affect the cockle fishery. Findings from interviews with shell collectors and analysis of catch-per-unit-effort (CPUE) indicate that mangrove concessions as common property regimes promote community empowerment, local autonomy over resources, mangrove conservation and recovery, higher cockle catch shares, and larger shell sizes, but the benefits are not evenly distributed. Associations without <em>custodias </em>and independent cockle collectors feel further marginalized by the loss of gathering grounds, potentially deflecting problems of overexploitation to “open-access” areas, in which mangrove fisheries are weakly managed by the State. Using Ostrom’s Institutional Analysis and Development (IAD) framework, the explicit link between social and ecological systems is studied at different levels, examining the relationship between collective action and the environment through quantitative approaches at the fishery level and qualitative analysis at the level of the mangrove landscape. Implications for coastal and fishery management are discussed in the conclusions.

Is the mangrove cockle Anadara tuberculosa a candidate for effluent bioremediation? Energy budgets under combined conditions of temperature and salinity

To determine extreme and optimum temperature and salinity for growth in the mangrove cockle Anadara tuberculosa, we measured the scope for growth in adult cockles exposed to 16 treatments composed of combinations of four salinities (20, 30, 40, and 50 psu) and four water temperatures (23, 26, 29, and 32 °C). Higher clearance rates were recorded in cockles maintained at 30 and 40 psu and 32 °C. Consistently high clearance rates (0.9 to 1.14 l g –1 h –1) were recorded in cockles held at 40 psu, regardless of temperature. Absorption efficiency was higher at 20 psu and lowest at 40 and 50 psu. Absorbed energy increased with decreasing salinity and increasing temperature. Respiration energy was higher at low to moderate salinities (20 to 40 psu) and at intermediate temperatures (26 and 29 °C). The lowest respiration energy and excretion energy were recorded in cockles held at 50 psu, regardless of temperature. Excretion energy was inversely related to temperature and salinity, with high values in cockles held at low salinity (20 and 30 psu) and low temperature (23 and 26 °C). Scope for growth was directly related to temperature and inversely related to salinity. The highest scope for growth occurred in cockles held at 32 °C (120.4 to 327.3 J g –1 h –1) and the lowest in cockles held at 23 °C (4.3 to 84.1 J g –1 h –1). The mangrove cockle can tolerate a wide range of temperature and salinity and maintain positive scope for growth. This species could be grown under a wide variety of conditions, especially in tropical lagoons receiving fresh water runoff. However it can also be grown in challenging environments such as shrimp ponds effluents and take advance of the cockle tolerance to extreme conditions.

Gut content analysis of Anadara tuberculosa (Sowerby, 1833) through histological sections.

The intestinal content of 30 specimens of Anadara tuberculosa collected from the Pacific coast of the Baja California Peninsula in April, May, June and October 2000 and histological sections of the intestine and stomach were made; I know they found 1002 structures. Of these, 917 corresponded to diatoms (91.5%), of which, the benthic diatom Paralia sulcata (45.3%) and the planktonic diatoms Thalassiosira spp. (42.9%) and Thalassionema nitzschioides (2.7%) were the most frequent. The silicoflagellate Dictyocha sp. (1.6%) it was not very abundant. Likewise, 85 structures (8.5%) that consisted of eggs of bivalves (1.8%), sponge spicules (0.4%) and unidentified material (6.3%). Histological sections represent a new alternative for the study stomach and intestinal contents for this bivalve.

Growth estimation of mangrove cockle Anadara tuberculosa (Mollusca: Bivalvia): application and evaluation of length-based methods

Growth is one of the key processes in the dynamic of exploited resources, since it provides part of the information required for structured population models. Growth of mangrove cockle, Anadara tuberculosa was estimated through length-based methods (ELEFAN I y NSLCA) and using diverse shell length intervals (SLI). The variability of L(infinity), k and phi prime (phi') estimates and the effect of each sample were quantified by jackknife techniques. Results showed the same L(infinity) estimates from ELEFAN I and NSLCA across each SLI used, and all L(infinity) were within the expected range. On the contrary, k estimates differed between methods. Jackknife estimations uncovered the tendency of ELEFAN I to overestimate k with increases in SLI, and allowed the identification of differences in uncertainty (PE and CV) between both methods. The average values of phi' derived from NSCLA1.5 and length-age sources were similar and corresponded to ranges reported by other authors. Estimates of L(infinity), k and (phi' from NSCLA1.5 were 85.97 mm, 0.124/year and 2.953 with jackknife and 86.36mm de L(infinity), 0.110/year de k and 2.914 de phi' without jackknife, respectively. Based on the observed evidence and according to the biology of the species, NSCLA is suggested to be used with jackknife and a SLI of 1.5 mm as an ad hoc approach to estimate the growth parameters of mangrove cockle.

A preliminary evaluation of physiological filtration variables forCrassostrea corteziensis(Hertlein, 1951) andAnadara tuberculosa(Sowerby, 1833) in shrimp aquaculture effluents

This study examined the main filtration variables [filtration rate (FR), clearance rate (CR) and assimilation efficiency (AE)] of the Cortez oyster, Crassostrea corteziensis (Hertlein, 1951), and the mud cockle, Anadara tuberculosa (Sowerby, 1833), in shrimp aquaculture effluents at three different flux velocities (1.5, 3 and 4.5 L h−1) using a 36-respirometer system, each with a 0.5 L capacity. Under inverted photoperiod conditions, free variations in the environmental parameters were allowed to mimic effluent conditions during a pair of 12-h trials. The FRs for both species (0.124, 0.328 and 0.402 L h−1 for the Cortez oyster; 0.093, 0.189 and 0.345 L h−1 for the mud cockle) were relatively low as compared with those reported for similar or related species. The CRs were higher for the Cortez oyster (20.04, 52.92 and 64.70 L h−1) than for the mud cockle (10.96, 22.95 and 42.12 L h−1); in both cases, the values were in the range reported previously for the last species. The AE for both mollusks (over 92% for the Cortez oyster and over 95% for the mud cockle) was very high and greater than that found by other authors for the same or related species. The three filtration variables were better at higher effluent flux velocities. These preliminary results strongly suggest that both species are good candidates to be considered for bioremediation of aquaculture effluents.

Growth and Fisheries of the Black Ark Anadara tuberculosa, a Bivalve Mollusk, in Bahía Magdalena, Baja California Sur, Mexico

AbstractTo determine trends in landings and growth of the pustulose ark or black ark Anadara tuberculosa, a bivalve mollusk in the Bahía Magdalena–Bahía Almejas region along the southwestern coast of the Baja California Peninsula, Mexico, catch statistics recorded by artisan or small‐scale fishermen from 1992 to 2002 and size frequency distributions of samples from commercial catches (November 1998–December 2000) were analyzed. Catch data revealed considerable fluctuations and a trend toward decline. No defined seasonal exploitation pattern was observed; however, on average, the months with the highest catches coincided with the highest reproductive activity. There was evidence of a decrease in black ark density, which might be accounted for by the fishery. Parameters derived from the von Bertalanffy growth equation confirm that individuals reach the minimum catch size of 60 mm in a little more than 1 year. Catch sizes ranged between 40 and 80 mm.

Population dynamics and fisheries potential of Anadara tuberculosa (Bivalvia: Arcidae) along the Pacific coast of Costa Rica

The present study aims to describe the population dynamics and state of the fishery of the mud cockle Anadara tuberculosa (locally know as piangua) in three harvesting areas along the Pacific coast of Costa Rica (Chomes, Purruja and Rincon) and to put the results in context with this species in other Costa Rican areas as well as with other Anadara spp. around the globe. The study is based on a five-month sampling period from October, 2003 through April, 2004 during which monthly length frequency measurements and tagging experiments were carried out. Von Bertalanffy growth parameters, K and L∞, (0.14 and 63.15, respectively) revealed a growth performance (f’= 2.75) which is in the range of reported values for this family of bivalves, indicating the accuracy of these values. Estimated exploitation rates range from 0.62 (Rincon) to 0.76 (Purruja) and exceed sustainable levels at all study sites. The strong overharvesting in these areas, also mirrored by the low average harvested cockle sizes relative to less exploited areas of Costa Rica and elsewhere, is due to the relatively small clam populations in each fishing area, the easy accessibility and the high economic importance of the species to the local resource users. If conservation measures are not implemented it is probable that A. tuberculosa may follow its formerly abundant and bigger sister species, Anadara grandis (chucheca), on its way to local extinction. Rev. Biol. Trop. 54 (Suppl. 1): 87-99. Epub 2006 Sept. 30.

Toxicidad Aguda y Bioacumulación de dos Hidrocarburos aromáticos Policíclicos (Naftaleno y Fluoranteno) en un molusco Bivalvo

In the present study was determined the susceptibility of the bivalve mollusk Anadara tuberculosa, to two polycyclic aromatic hydrocarbons (naphtalene and fluoranthene), high-priority pollutants of the Environmental Protection Agency (EPA) due to its genotoxic and cancerigenic potential. It carried out tests of acute toxicity, in the that this specie was exposed to the action of each one of these compounds during 96 hours and later on, starting from the obtained information, were developed bioaccumulation tests by a period of 30 days. The lethal concentrations (CL50 96h) equivalent to 8.66 ppm for the test carried out with naphtalene and of 113.47 ppm corresponding to the fluoranthene. The analysis of the bioaccumulation levels allowed to evaluate the cycle of absorption, retention and excretion of these hydrocarbons in the organisms, observing values that oscillated between 0.16 and 3.42 ppm for the naphtalene, while for the fluoranthene, the range of accumulation was between 194.77 and 1011.30 ppm. These results evidence a higher concentration capacity for the fluoranthene, related with their physiochemical characteristics and of toxicity. The contamination for hydrocarbons can cause a serious economic impact in the coastal activities and affect to the communities that exploit the marine resources and the accumulation of this substances in the organisms can represent a potential problem of public health