Links between phytoplankton dynamics and shell growth of Arctica islandica on the Faroe Shelf

2018 ◽  
Vol 179 ◽  
pp. 72-87 ◽  
Author(s):  
Fabian Georg Wulf Bonitz ◽  
Carin Andersson ◽  
Tamara Trofimova ◽  
Hjálmar Hátún
2000 ◽  
Vol 53 (2) ◽  
pp. 236-246 ◽  
Author(s):  
Thomas M. Marchitto ◽  
Glenn A. Jones ◽  
Glenn A. Goodfriend ◽  
Christopher R. Weidman

AbstractAnnual growth bands of mollusk shells record several types of paleoenvironmental information, including geochemical proxies for water properties and morphological characteristics of growth and mortality. Sclerochronology, the marine counterpart of dendrochronology, offers a way to link individual shells together to form long continuous records of such parameters. It also allows for precise dating of recent shells and identification of contemporaneous fossil individuals. The longevity of the ocean quahog Arctica islandica (commonly >100 yr) makes this species well suited for sclerochronology. Band width records of contemporaneous A. islandica specimens from the same region exhibit high correlations (ρ = 0.60–0.80 for spans of ≥30 bands), indicating some common environmental influences on shell growth. By adopting several strict criteria, fossil (dead-collected) shells can be linked into composite sclerochronologies. A seven-shell 154-yr chronology was constructed for Georges Bank using three live-collected and four dead-collected shells. Band width matching indicates that the dead-collected individuals died in A.D. 1950, 1971, 1978, and 1989. Sclerochronological age assignments were verified using aspartic acid racemization dating. Construction of a 1000-yr sclerochronology is judged to be feasible using the described methods.


Paleobiology ◽  
1980 ◽  
Vol 6 (3) ◽  
pp. 331-340 ◽  
Author(s):  
Douglas S. Jones

The bivalvesSpisula solidissima, the Atlantic surf clam, andArctica islandica, the ocean quahog, from the continental shelf off New Jersey, contain repeating structures in their shells. By analyzing the growing shell margins in living specimens at bi-weekly (or sometimes monthly) intervals throughout two consecutive years, it was possible to define an annual cycle of shell growth increment formation in both species. The shell increments in each species are microstructurally distinct units that form over a period of several months at select seasons of the year. Each species has two alternating shell growth increments, GI I and GI II. GI I (the annual growth line of previous studies) is formed annually in the late summer-fall inS. solidissimaand in the fall-early winter inA. islandica.These periods correspond to the spawning phase of the reproductive cycle in both species. No winter rings were found. The annual increments were used to determine age and growth rate in both Recent and Pleistocene specimens. They may also be useful in determining season of death. Because shell growth increments are formed in synchrony among living populations in these species, mass mortalities may be distinguished in the fossil record. Accurate age and growth rate determinations in fossils are important in many paleobiologic contexts, such as deciding between increased longevity or growth rate in cases of phyletic size increase.


2006 ◽  
Vol 64 (1) ◽  
pp. 31-38 ◽  
Author(s):  
Raouf W. Kilada ◽  
Steven E. Campana ◽  
Dale Roddick

Abstract Kilada, R. W., Campana S. E., and Roddick, D. 2007. Validated age, growth, and mortality estimates of the ocean quahog (Arctica islandica) in the western Atlantic. ICES Journal of Marine Science, 64: 31–38. The age structure of offshore (Sable Bank) and inshore (St Mary's Bay) populations of eastern Canadian ocean quahogs (Arctica islandica), and of a northwestern Iceland population, is investigated. Age estimates for eastern Canadian ocean quahogs were validated through analysis of bomb-produced 14C in quahog shell growth increments deposited before, during, and after the atmospheric atomic bomb testing periods of the 1950s and 1960s. Delta 14C from shells with presumed birthdates between the late 1950s and 1970s clearly reflects the sharp increase in oceanic radiocarbon attributable to nuclear testing. The results validate our age interpretations of Sable Bank quahogs to an age of 45 y, and support longevity estimates of more than 200 y for the same population. Longevity calculations for the other populations exceeded 60 y. Von Bertalanffy growth parameters were estimated for the three populations; the growth rate of all three was relatively rapid for the first 20–30 y of life, but thereafter was very slow. The instantaneous rate of natural mortality (M), calculated using the age–frequency distribution of the unexploited populations, was estimated to be 0.03 and 0.10 for the Sable Bank and St Mary's Bay populations, respectively.


2020 ◽  
Vol 237 ◽  
pp. 106628 ◽  
Author(s):  
Justine Doré ◽  
Gwénaëlle Chaillou ◽  
Pierre Poitevin ◽  
Pascal Lazure ◽  
André Poirier ◽  
...  

Author(s):  
R. Witbaard ◽  
G.C.A. Duineveld ◽  
P.A.W.J. De Wilde

Long-term variations in shell growth of the mollusc Arctica islandica (Mollusca, Bivalvia) from the northern North Sea have been assessed retrospectively using the annually deposited internal growth lines. Relatively young specimens yielded a detailed year-to-year chronology while the growth record of specimens older than 30 y yielded a time series with a length exceeding 100 years. The long-term growth trends demonstrated a marked alternating sequence of periods in which growth was below and above expectation. A 33-y long cycle could be discerned. Since the 1960s the growth patterns in Arctica from two nearby locations were opposite, while they resembled each other in the period before 1960.


Author(s):  
R. Witbaard ◽  
G.C.A. Duineveld ◽  
P.A.W.J. de Wilde

Geographical differences in the shell growth rate of several populations of the bivalve Arctica islandica (Mollusca: Bivalvia) were estimated by using the growth lines laid down during their first ten years of life. Attention was focused on populations from the North Sea, but for comparison small samples from adjacent waters were also analysed. A four-fold difference in the average growth rate was found between the slowest and fastest growing shells.Principal component analysis was used to summarize the inter-relationships between environmental variables and growth rates. Shell growth correlated positively with primary production and temperature and inversely with depth and the silt content of the sediment. The North Sea specimens were found to have a strong positive correlation with grain size. Since sediment characteristics also depend on bottom currents, it is suggested that these increased rates reflect lateral seston flux as additional food supply.In a multiple regression model, applied to all available data, average annual temperature, primary production and the interaction between production and water depth explained 50% of the variance. The derived standard coefficients for temperature, primary production and the interaction between depth and primary production were 0.90, 0.47 and −0.92 respectively. The results of this study suggest that the temperature effects on in situ shell growth are easily overruled by other environmental factors.If a similar model was calculated with North Sea data only, 75% of the variance was explained by temperature, primary production and depth×primary production. The standard coefficient for primary production was 1.26. The role of temperature in explaining the observed growth differences is negligible since the standard coefficient is −0.098. The interaction term, depth×primary production had a standard coefficient of −0.95.


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