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Shell growth of the cockle Cerastoderma edule in the mundaca estuary (North Spain)
Abstract
In order to establish a growth curve for the life-span, age determination based on shell-ring analysis was undertaken in a
population of the cockle Cerastoderma edule located in the Mundaca Estuary (Basque Country, North Spain). Mean values of height at shell rings showed non-significant
differences between generations, meaning absence of interannual variations in growth rate. Frequent sampling and shell measurements
over a 20 month period allowed determination of the seasonal pattern of shell growth, which was subsequently incorporated
into a growth curve.
An attempt has been made to relate growth rates to latitude for different populations of C. edule, using both data from the literature and the results of this study. The highly significant correlation found (P<0.01) confims
the existence of a latitudinal trend, with growth rates increasing southwards. Low rates of growth recorded for cockles from
Mundaca, by camparison with pupulations of similar latitude, are interpreted in terms of nutritional restrictions associated
with both the high tidal position of the population and poor productivity conditions within this particular estuary.
... However, to our knowledge, since this study (Iglesias and Navarro, 1990), no further reports of cockle growth variations over a latitudinal gradient have been published. ...
... However the historic survey indicated that latitude (and likely temperature) may potentially impact cockle growth parameters, with cockles reaching larger asymptotic average length ( ∞ ) at northern sites. Furthermore, these results may agree with a previous study where cockles grew faster (to smaller sizes) at southern latitudes (Iglesias and Navarro, 1990). Differences between these studies may be attributed to climate, with the Atlantic Multidecadal Oscillation shifting to a positive phase (i.e. ...
A better understanding of growth drivers in shellfish populations including the common cockle Cerastoderma edule is essential, as their future is challenged by unsustainable fishing practices and climate change. In this study the spatial and temporal variabilities in common cockle growth across latitudes were assessed and compared with historical data. Six locations were examined at bimonthly intervals over 19 months; three Irish, two Welsh and one French, spanning the latitudes 54°N to 44°N. The results demonstrated that local abiotic and biotic factors have a larger impact on cockle growth than latitude. Cockles at similar latitudes grew at different rates and sizes, possibly due to factors such as density, fishing activity and interspecific competition. Cockles (0–3 years) impacted by low salinity and parasites (trematodes), exhibited reduced growth in later years. At the warmest, southernmost site growth was lowest in cockles >2 years. Previously, cockles at that site have been shown to spawn almost year-round, possibly diverting energy to gonad development rather than growth. The results opposed previously literature which demonstrated significantly greater growth at lower latitudes. These findings affirm that cockle growth and size is variable due to local abiotic (reduced salinity) and biotic (potentially trematode infection) drivers. Additionally, the synergistic relationship between these factors, i.e. warmer temperatures driving prolonged spawning, and the potential association between lower salinities and trematode prevalence, is concerning due to predicted climate related increases in temperature, precipitation and trematode prevalence/transmission, which may result in northern cockles reaching smaller maximum sizes.
... temperature and food availability). Water temperature, and its indirect effect on food availability, can influence growth and the reproductive cycle pattern of C. edule (Boyden, 1971;Dabouineau and Ponsero, 2009;Malham et al., 2012;Martinez-Castro and Vázquez, 2012) and has been considered a key driver of latitudinal gradients in growth and reproduction traits of the species (Cole, 1956;Iglesias and Navarro, 1990;Gam et al., 2010). In this respect, there is a growing scientific debate regarding the risks of global warming on aquatic ecosystems, particularly those of shallow coastal areas (the typical habitat of the common cockle) that are considered to be highly climate dependent and therefore particularly sensitive to temperature change scenarios. ...
... The noteworthy exception to this pattern was recorded in a cockle population inhabiting Mundaca Estuary, North Spain (L∞ = 28.3 mm, k = 0.026), but it was attributed to severe nutritional restrictions associated to long periods of emersion (shorter feeding times) and poor productivity conditions in this specific estuary, limiting factors that restrain growth (Iglesias and Navarro, 1990). Accordingly, the VBG parameters recorded in Ria de Aveiro (L∞ = 40.7 mm, k = 0.74) were similar to those obtained by Pérez Camacho and Román (1984) in Ria de Arosa, NW Spain (L∞ = 41.2 mm, k = 0.951), the nearest location of our study area, though an enhanced growth rate in Ria de Arousa may be attributable to higher levels of primary production (Alvarez et al., 2013). ...
This study reports the reproductive cycle, condition index, size at first maturity, growth and the morphometric relationships of the common cockle Cerastoderma edule in Ria de Aveiro (NW Portugal), fundamental knowledge in fisheries management planning and ecosystem conservation. The reproductive cycle was monitored for a period of two years, from January 2013 to December 2014. Spawning extended from June to October, with a peak in the summer months (July to September). The condition index showed a seasonal pattern which appear related to food availability and gametogenic cycle. Sexual maturity was attained at a shell length of 18.6 mm during the first year of life, which stands below the minimum landing size currently in force (25 mm). The von Bertalanffy growth equation was based on size-at-age data obtained from the microscopic analysis of growth rings in sectioned shells: Lt = 40.7[1-e −0.74(t-0.30)]. The morphometric relationships between shell dimensions (length, height and width) were also studied in order to understand the effects of ontogenetic changes in cockles` shell morphology, an information that is useful to improve the selectivity of the fishing gears and the size-sorting devices. Some management strategies for the Ria de Aveiro cockle fishery were proposed.
... In most of the experimental work done, the age exceeds 6 years for some populations. In conditions with increased mortality and poor growth, the figure can often be reduced to 2-3 years maximum [37][38][39]. ...
The bivalve species Cerastoderma glaucum (Poiret, 1789) was studied in this study. This species is allochthonous and belongs to the Mediterranean zoogeographic complex and was introduced in the Holocene. The C. glaucum is the dominant species among the bivalves in the Sea of Azov and has a wide range of distribution. The species is distributed in the coastal zone within 100-300 m from the shore, and it is also found in desalinated water bodies such as estuaries. The C. glaucum is fairly resistant to hypoxia. It is euryhaline with respect to salinity and eurybiontic with respect to soil. The species can settle on sandy, muddy or sandy-silty substrate. The aim of the study was to investigate the morphology of shells of this species in order to find out the reasons of morphological features change of Cerastoderma glaucum in different biotopes of the Sea of Azov. The study was conducted in early June 2021 on the northwestern coast of the Azov Sea. A total of 20 stations were investigated. Cerastoderma glaucum was found at all stations. The morphological variability of the bivalve Cerastoderma glaucum was investigated using the method of discriminant analysis. A notable morphological feature was the external alteration of the mollusc shell. A displacement of the apex to the anterior edge of the shell, lengthening of the posterior edge, and deformation of the shell shape, indicating the ecological characteristics of the study area and its inhabitants. Also, there is a difference in the ratio of shell height to shell length, indicating an increased level of siltation in the ground. Shell thickness varies in all survey areas, indicating different levels of salinity. The overall abundance of molluscs from the different biotopes indicates the factors determining the shape of cockle shells. In turn, morphological parameters indicate the general condition of the Sea of Azov. So, it can be assumed that siltation of the substrate on which benthic communities are located has increased as a consequence of massive deposition of phytoorganic residues. In addition, the hydrolytic regime has changed as a result of anthropogenic factors. As a consequence, salinity, oxygen levels are changing, etc.
... The assessment of the abundance, distribution and populational structure of a given species is a requirement for the assessment of stocks. The analysis of length-frequency distributions is one of the methods used to study the population structure and may give indications about the success of the recruitment process (Iglesias and Navarro, 1990;Ramón, 2003). Given that cockles represent an important economic resource subject to multiple anthropogenic pressures, the present work assumes an important contribution so that in the future, stocks of these populations can be managed more sustainably, with adapted management policies. ...
Cockles are amongst the most exploited bivalve species in Portugal, playing an important ecological and socioeconomic role in coastal ecosystems. Two sympatric species of cockles, Cerastoderma edule ( Linnaeus, 1758 ) and Cerastoderma glaucum ( Bruguière, 1789–1792 ) may co-occur in estuaries and coastal lagoons in mixed populations along the European Atlantic coast, namely in Portugal, France and the United Kingdom. The increasing importance of shellfish harvesting in Portugal requires a good knowledge of cockle stocks and temporal variability in stock levels to better inform sustainable management practices. Therefore, this study aimed at assessing spatial and temporal variations in cockle populations in two Portuguese estuarine systems where the species are exploited at low levels. Sampling was carried out using a clam dredge, covering the entire potential area of occurrence of cockles in the Tagus and Sado estuaries at around the same time of the year in each of the three sampling years (2015, 2018, and 2019). The abundance, spatial distribution and population structure of cockles were examined at each system. Moreover, several water and sediment parameters were measured to understand the influence of environmental conditions on the spatial distribution and abundance of cockles. The results obtained showed that cockles occur mostly in the intermediate areas of both estuarine systems and are more abundant in the Tagus estuary. Depth, average sediment grain size and the species Ruditapes philippinarum were the factors that better explained the probability of species occurrence. The population structure analysis indicated that natural mortality is constraining the cockle communities given the low abundance of adult individuals with marketable size in both estuaries. This study highlights the need for appropriate management measures to ensure the sustainability of these bivalve population stocks that have significant socioeconomic importance for local populations.
Bivalve populations are prone to change due to sudden or gradual alteration in the natural environment and anthropogenic interference. Fisheries and environmental managers are therefore interested in long-term trends and disentangling natural and human influences, assisting them in conservation efforts and the management of bivalve stocks. Here, 64 monitoring reports covering a 50-year period from 1958 to 2009 of cockles Cerastoderma edule (Linnaeus, 1758) in South Wales, UK, were scrutinised for data on recruitment, growth and mortality. Changes in these population parameters were related to the modernisation of wastewater treatment in 1997, weather and climate variables (temperature, sun hours, air frost days, NAO) and numbers of cockles in the estuary. Recruitment as well as mortalities were high during the first and last decade of the study, and variation was significantly linked to the total number of cockles in the population. Cockle sizes of all cohorts as well as overall biomass declined in the late 1990s. Modernisation of wastewater treatment was significantly related with the downward trend, suggesting that the changed nutrient regime in the estuary may have resulted in reduced food provision for cockles. The average size of newly settled cockles was related to their mortality: the smaller the recruits the higher their mortality. The study indicated a link between the change in wastewater treatment in 1997 and diminishing sizes of cockle recruits that shortened their life span. Survey methods were profoundly changed after 2009, and it is recommended to develop conversion factors between the pre- and post-2009 survey methods. This would allow an extension of the timeline and deeper insight into the long-term impact of the change in wastewater treatment and the recovery of the cockle population.
The cockle Cerastoderma glaucum represents one of the most common marine mollusc species present in Egyptian waters.
This study aims to investigate the population structure, growth, mortality, and exploitation status of this cockle along Lake
Qarun and Lake Timsah in order to make a comparison study. Cockles were collected from Lake Qarun at monthly intervals
between February 2008 and May 2009 and collected from Lake Timsah at four seasons only. Length frequency data were
analyzed using FiSAT software for estimation of population parameters to evaluate the stock. Asymptotic length (L∞) was
smaller in Lake Qarun (28.35 mm) compared to that in Lake Timsah (33.60 mm).Growth coefficient (K) was higher in Lake
Qarun (0.450 yr-1) than in Lake Timsah (0.280 yr-1).Growth performance index (Φ) values were similar (2.56) in both cockle
stocks. The theoretical maximum age (Tmax) was higher in Lake Timsah (12.6 yr-1) than in Lake Qarun (7.4 yr-1). Total
mortality (Z) was estimated by length-converted catch curve at 1.02 and 0.24 yr-1, fishing mortality (F) at -0.04 and 0.47 yr-1
and natural mortality (M) at 1.06 and 0.71 yr-1 for Lake Qarun and Lake Timsah, respectively. Recruitment was continuous
and showed two major pulses in the two lakes.
Keywords: Growth, mortality, recruitment, FiSAT II, Lake Qarun, Lake Timsah, Egypt
The cockle Cerastoderma glaucum represents one of the most common marine mollusc species present in Egyptian waters. This study aims to investigate the population structure, growth, mortality, and exploitation status of this cockle along Lake Qarun and Lake Timsah in order to make a comparison study. Cockles were collected from Lake Qarun at monthly intervals between February 2008 and May 2009 and collected from Lake Timsah at four seasons only. Length frequency data were analyzed using FiSAT software for estimation of population parameters to evaluate the stock. Asymptotic length (L∞) was smaller in Lake Qarun (28.35 mm) compared to that in Lake Timsah (33.60 mm).Growth coefficient (K) was higher in Lake Qarun (0.450 yr⁻¹) than in Lake Timsah (0.280 yr⁻¹).Growth performance index (Φ) values were similar (2.56) in both cockle stocks. The theoretical maximum age (Tmax) was higher in Lake Timsah (12.6 yr⁻¹) than in Lake Qarun (7.4 yr⁻¹). Total mortality (Z) was estimated by length-converted catch curve at 1.02 and 0.24 yr⁻¹, fishing mortality (F) at -0.04 and 0.47 yr⁻¹ and natural mortality (M) at 1.06 and 0.71 yr⁻¹ for Lake Qarun and Lake Timsah, respectively. Recruitment was continuous and showed two major pulses in the two lakes. © Published by Central Fisheries Research Institute (CFRI) Trabzon, Turkey.
Histological examination of the great tellin Megangulus venulosus revealed the developmental process of germ cells which is divided into four stages, as follows : in female, they are oogonia, yolkless oocytes, yolk granule oocytes, and mature oocytes ; in male, they are spermatogonia, spermatocytes, spermatids, and spermatozoa. An annual breeding cycle is composed of recovery period (March-May), growing period (May-August), mature period (September), spawning period (October), and spent period (November-February). Growth curve in shell length estimated by external growth rings shows a lower growth rate than previously reported tellinid bivalves. Shell length at the first sexual maturity defined as the length class at which 50 % of the clams mature is 50-55 mm for male and 65-70 mm for female. Based on the number of external growth rings, these sizes correspond to the age of six for male and eight for female. All the clams become mature when they grow larger than 75 mm in shell length. It takes about 10 years for the entire population of M. venulosus to become sexually mature.
Monthly measurement of growth rings along the shell margin of the North Pacific cockle Clinocardium californiense revealed that a ring is formed annually in September (above one year-old) or in October (0 year-old), when the bottom temperature is high. Age was determined by counting the number of growth rings on the shell. The VON BERTALANFFY growth equation was fitted to the age-shell length relation, and the equation, LT=57.14(1-exp(-0.526(T-0.143))) is obtained, where LT is the shell length (mm) at age T (year). Seasonal growth pattern was estimated by measuring the monthly shell increment from the last growth ring, and the equation obtained is LT=57.35[1-exp(-0.522(T-0.241)+0.085sin(2π(T-0.476)))]. These equations show nearly the same growth rates with those previously reported for cardiid cockles, but are higher than those for other bivalves.
Observations on the growth of cockles have emphasized the difficulty of choosing a single minimum size to cover a large area of coastline. A study of the mechanism of mesh selection showed that shell width is an important agent of selection by both square-meshed and oblong-meshed sieves, but the effects of selection need to be interpreted in the length dimension by which growth is measured. Growth rates within a single year-class have been examined, and the effects of time of settlement and rate of growth on the sizes achieved in subsequent years considered. The effects of selection by sieving on the mean lengths of annual growth checks on the shells, from which growth rates may be determined by back-measurement, have been examined. It was concluded that on average slower-growing cockles remain after selection, but the proportion of narrow-shelled apparently faster-growing cockles will increase.
(1) This study examines the growth of two marine bivalves, Modiolus modiolus (L.) and Cerastoderma edule (L.) in Strangford Lough, N. Ireland, the former from the relatively stable conditions of subtidal reefs, the latter from midtidal sand flats where environmental conditions are less predictable. (2) Cerastoderma grows rapidly in its first year after settlement. It first reproduces during its second year and the resumption of rapid growth is thus generally delayed until spawning has been completed. In subsequent years, growth becomes progressively slower. (3) In Modiolus reproduction is delayed and rapid growth can thus continue for a period of several years. (4) The growth strategies exhibited by these bivalves may reflect the essentially different patterns of mortality experienced by these two populations. In Cerastoderma, mortality is heavy in all age classes and relatively few cockles survive beyond their third year. Early reproduction following a period of very rapid growth is therefore probably the optimal strategy for this species. Modiolus, by contrast, experiences intense predation early in life but can escape further predation by growing too large to be eaten; only then is energy redirected towards reproductive development. These large but slower growing mussels then enjoy enhanced longevity.
1. Growth rate and longevity were determined for a population of M. balthica at Rand Harbor, Falmouth, Mass., using a modification of the mark and recapture technique that allowed all marked individuals to be followed throughout a year. Dry weight biomass, dry shell weight and caloric content were also determined.2. Caloric content is 4.049 kcal/ash-free g. Dry weight biomass and dry shell weight were found to have a similar allometric growth with a constant of allometry of approximately 3 when measured against shell length.3. The bivalves were discovered to grow year round with the peak period of growth occurring from May to August. A negatively linear relationship between initial length (X) and total annual increment (Y) was found (Y= -0.59 X + 12.85).4. The growth curve for the Rand Harbor population revealed that within the first two years of life, M. balthica attains most of its total length. Growth ceases once a maximum size of 22-25 mm is reached and total longevity is estimated to be 6-10 years.5....
1. Rates of growth have been studied in populations of Mytilus californianus collected from southern California and southeastern Alaska. As nearly as possible natural rates of growth have been determined from populations in the field.2. Length, width and height of the shell are used as criteria for determining rates of growth in this species. Comparisons of rates of growth between northern and southern populations are made by the use of relative rate (k) values.3. Mussels were measured at the 1.0 ft. and 3.0 ft. tidal levels in southern California and the 5.5 ft. level in Alaska.4. Rates of growth of Mytilus are found to he greater in the sample from southern California, comparing the 3.0 ft. level, than in that from Alaska. However, it was found that the southern California population is submerged for a greater period of time per week. The greater period of submergence and the greater weight of soft parts for a given shell size, recently shown by Rao (1953) for the southern population, mean a greater foo...
Settlement, growth and reproductive output of a population of Choromytilus meridionalis have been monitored at different shore levels at Bailey's Cottage, False Bay, South Africa. Settlement was irregular, occurring at 4- to 6-year intervals, and confined to the sublittoral and lower littoral of rocky areas. Spat settled on the existing mussel bed and adjacent clean rock surfaces. Continual migration of young mussels up the shore took place during the first 1 to 1·5 years of growth until an even distribution up to 0·5 m above L.W.S. was achieved. Juveniles displaced older individuals by moving between them and forcing them off the rocks so that the majority of the adult population were eliminated from the bed within the first year after spat settlement. Mortality in individual cohorts was largely caused by strong wave action and competition for space. The density of individuals within the mussel bed was closely related to mean shell length.
Growth rates varied with habitat and declined markedly with increasing height above L.W.S.
Sexual maturity was attained at approximately 20 mm and reproductive output rose from 5 kJ year−1 at this length to 80 kJ year−1 at 100 mm shell length. Since packing densities were much higher in smaller individuals the annual gamete output assessed on an area basis, remained fairly constant as the mussels grew, and averaged 1392 g m−2 year−1 dry weight (31 320 kJ m−2 year−1). Energy expended as gonad output exceeded that due to mortality by a factor of 10.
1.1. The aerial oxygen consumption of an air-breathing littoral cockle, Cerastoderma edule, has been measured over the temperature range (7·5–30°C) in animals collected during winter and summer.2.2. Respiration in air has been shown to be temperature dependent.3.3. A Q10 of 1·88 between 10 and 25°C was observed in summer acclimated cockles, whilst a value of 2·53 was obtained between 10 and 20°C in the winter acclimated group.4.4. Comparison is made with data available from R to T curves of other air-breathing littoral poikilotherms .