Reproductive cycle of the Manila clam (<i>Ruditapes philippinarum</i>): an intensively harvested invasive species in the Tagus Estuary (Portugal)

Moura, Paula; Vasconcelos, Paulo; Pereira, Fábio; Chainho, Paula; Costa, José Lino; Gaspar, Miguel B.

doi:10.1017/s0025315417001382

Cited by 20 publications

(7 citation statements)

References 54 publications

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“…Since both sexes of the three clam species and the cockle show synchrony in the stages of gonadal development (R. decussatus: Matias et al, 2013;Genez et al, 2015;R. philippinarum: Drummond et al, 2006;Moura et al, 2018;V. corrugata: Joaquim et al, 2011;C.…”

Section: Discussionmentioning

confidence: 99%

“…This could lead to a failure in the recruitment that, sustained over time, and together with overfishing (Massapina and Arrobas, 1991;Maia et al, 2006) could be the reason for the decrease of the populations of this clam. Consequently, the introduced Manila clam with faster maturation, greater number of spawning events, longer and greater reproductive activity, faster growth (Laruelle et al, 1994;Delgado and Pérez-Camacho, 2007;Moura et al, 2017Moura et al, , 2018 and greater tolerance to salinity and temperature stress (Domínguez et al, 2020(Domínguez et al, , 2021 contribute to the observed larger abundance of the introduced clam. Furthermore, R. philippinarum, but not R. decussatus, is typically seeded in shellfish beds (e.g., Royo et al, 2002;Melià and Gatto, 2005;Mantovani et al, 2006) artificially increasing its abundance.…”

Section: Discussionmentioning

confidence: 99%

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Reproduction Under Stress: Acute Effect of Low Salinities and Heat Waves on Reproductive Cycle of Four Ecologically and Commercially Important Bivalves

et al. 2021

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The impacts of climate change on the structure and functioning of estuaries is a major focus of concern, even more when the affected species support important fisheries as the bivalves Ruditapes decussatus, Ruditapes philippinarum, Venerupis corrugata, and Cerastoderma edule in Europe. Their reproductive performance, in the context of climate stressors, had not been investigated so far. Our objective was to experimentally evaluate acute stress effects over gonad development after 6 days of low salinity stress in autumn, winter and spring as well as 4 days of heatwave stress during emersion in summer. These are the most probable extreme events that bivalves should face in our latitudes. Four different salinity ramps (5–20, 10–25, 15–30, 30–30) were created during simulated tidal cycles in mesocosms for the low salinity experiments. Also four sediment heatwaves at emersion (20–20, 20–27, 20–32, 20–37°C) were done during simulated tidal cycle. Both low salinity and heatwave stresses over such short periods compromised reproduction; the acute response was species-specific and varied with the time of the year, and therefore, with the stage of the gametogenic cycle. In December, during sexual resting and the beginning of gametogenesis, a delay in gametogenesis at lower salinities was recorded in the four species. However, at the peak of the reproductive period (March and May), different responses were observed: abnormal oocytes in R. decussatus and resorption of gametes with haemocytic infiltration in R. philippinarum and V. corrugata. Likewise sediment temperatures higher than 32°C provoked gonadal resorption and severe haemocytic invasion in V. corrugata, R. decussatus, and C. edule but had no effect in R. philippinarum. These responses to both environmental stressors might be related to the allocation of energy from reproduction toward defense and repair mechanisms to ensure survival. Contrastingly, low salinities triggered massive spawning in C. edule that could lead to a mismatch between the presence of larvae and phytoplankton, causing potentially starvation and thus reducing recruitment success. Reproduction of theses bivalves would be compromised if low salinity episodes in winter and spring, even for short periods of time such as those in these experiments, are followed by a heatwave in summer. Furthermore the impact would be magnified if this situation happens during consecutive years preventing replenishment of the shellfish beds.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Reproduction Under Stress: Acute Effect of Low Salinities and Heat Waves on Reproductive Cycle of Four Ecologically and Commercially Important Bivalves

et al. 2021

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“…The definition of seasonal closures to shellfish harvesting associated to the reproductive cycle is used as a management measure to ensure the replenishment of bivalve stocks. The Manila clam has an extensive spawning period, as was confirmed for the populations in the Ria de Aveiro (Maia et al, 2021) and the Tagus estuary (Moura et al, 2018), starting at the end of spring and extending until autumn. Nevertheless, this type of measure must be comprehensive, in order to protect the various exploitable species that co-occur in the same systems.…”

Section: Regulation Measuresmentioning

confidence: 60%

Management Models of the Manila Clam (Ruditapes philippinarum) Fisheries in Invaded European Coastal Systems

Coelho¹,

Carvalho²,

Goulding³

et al. 2021

Front. Mar. Sci.

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The Manila clam (Ruditapes philippinarum, Adam & Reeve 1850) is a non-indigenous species that was illegally introduced in Europe (France) in the 1970s for commercial purposes, and reached Portugal in the 1980s. Currently, it occurs in several European coastal systems, from the Bay of Biscay to the north Mediterranean. In Portugal, it is present in estuarine systems and coastal lagoons from the north to south, such as Ria de Aveiro, Óbidos Lagoon and Sado estuary, but a sharp rise in the prevalence of this species in the largest Portuguese estuary, the Tagus, resulted in the exponential growth of the number of harvesters and, consequently, an increase in the illegal exploitation of this resource. At least 1700 harvesters were estimated in this system and an annual catch volume of between around 4,000 and 17,000 t which corresponds to an annual value around €10,000,000 to €23,000,000 of sales. There is a general failure to comply with current legislation, both in relation to harvesting and marketing, as well as constraints arising from spatial planning instruments in force on the estuary. The failure to comply with sanitary standards for the exploitation and trade of bivalve mollusks presents a risk to public health and a social-economic issue resulting from this activity. The goal of this study is to propose management models for this activity with the aim of contributing to create a legal framework in which sustainable harvesting can be achieved, in the different systems where exploitation occurs. In order to accomplish this goal, the current state play, legal framework, regulation for harvesting and trade and relevant spatial planning instruments in Portugal are analyzed. In order to ascertain an adequate national management strategy, a variety of case studies in France, Spain and Italy were studied. The outcome is a management model which includes a co-management strategy of concessions as well as a mixed regime with concession areas and free areas. The creation of specific regulations; implementation of a co-management model with the active participation of harvesters; science-based regulation of a closed season and maximum daily quotas and an improved surveillance of the activity are recommended.

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“…Where to install new waste water treatment plants and where outfalls should be placed (or relocated), should take into consideration the ET and water exchange among areas of the estuary, in order to avoid the retention of large amounts of nutrients in the estuary for long periods of time, to promote their quick flush to the sea, and to improve the microbiological quality of the Tagus estuarine water. Bacterial contamination is a prevalent problem in the Tagus estuary that contaminates shellfish and affects an important harvesting bivalve activity (Moura et al, 2017(Moura et al, , 2018, which occurs prevalently in its main body. Recently, bivalve harvesting was forbidden in one of the most important bivalve fishing areas of the Tagus estuary due to the high levels of contamination of bivalves by Escherichia coli which is causing significant local socio-economic issues.…”

Section: Discussionmentioning

confidence: 99%

The Influence of the River Discharge on Residence Time, Exposure Time and Integrated Water Fractions for the Tagus Estuary (Portugal)

et al. 2022

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Understanding how long water is retained in an estuary and how quickly it is completely flushed is essential to estimate an estuary’s health in areas with significant pollutant loadings. The present study analyses the effect of five different Tagus River discharge scenarios ranging from low to extreme on residence time (RT), exposure time (ET) and integrated water fractions inside pre-established Tagus estuary areas, to identify its most vulnerable areas to pollution. The 3D version of the MOHID hydrodynamic model coupled to a lagrangian tool was used. The increase of the river discharge generated high current velocities which, in turn, led to an increased rate of tracers leaving the estuary. As a consequence, RT and ET decreased from 59 to 3.5 days under a low and extreme river discharge scenario, respectively. Under a low river discharge, significant differences were observed between RT and ET in the areas located in the main body of the estuary and in the bays. As river discharge increased, RT and ET decreased in all areas of the estuary and those differences faded, with the greatest differences observed in the areas situated along the south margin. In general, results showed that with high river discharges the tracers released in the upper estuary are spread throughout the estuary, but mainly in downstream areas. However, when the river discharge reached exceptionally high values, local eddies were formed, leading to the retention of the tracers in the estuary’s south margin and inner bays. The results in this study allowed to identify the most vulnerable areas within the estuary as a function of the river discharge.

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Reproductive cycle of the Manila clam (Ruditapes philippinarum): an intensively harvested invasive species in the Tagus Estuary (Portugal)

Cited by 20 publications

References 54 publications

Reproduction Under Stress: Acute Effect of Low Salinities and Heat Waves on Reproductive Cycle of Four Ecologically and Commercially Important Bivalves

Reproduction Under Stress: Acute Effect of Low Salinities and Heat Waves on Reproductive Cycle of Four Ecologically and Commercially Important Bivalves

Management Models of the Manila Clam (Ruditapes philippinarum) Fisheries in Invaded European Coastal Systems

The Influence of the River Discharge on Residence Time, Exposure Time and Integrated Water Fractions for the Tagus Estuary (Portugal)

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