Many water-stressed regions of the globe have a highly seasonal precipitation regime. However, seasonality in the past and under changing climates is little studied. Submonthly records of sclerochronological δ18O and δ13C values of Melanopsis shells from the Jordan River Dureijat archaeological site (JRD) in the upper Jordan River valley presented here document the hydrology of paleo-Lake Hula. These records were assessed for changes in seasonal hydrology in the lake and compared with modern shells collected from present-day waterbodies in northern Israel and with models of δ18Oshell. Results from shells in sediments dating from the last glacial maximum (LGM) to the Bølling-Allerød imply changes in waterbody size that qualitatively parallel changes in the late Pleistocene Lake Lisan levels; Hula Lake was well buffered when Lake Lisan stood at a high stand and poorly buffered when water levels were lower. Furthermore, data from shells dated to the LGM suggest inflowing water with lower δ18O values than local rainfall, providing evidence for a greater proportion of snow in the catchment than today. Reconstruction of water δ18O and mixing-model calculations suggest that snowmelt contribution to spring water during the LGM may have been more than twice the amount in the modern-day catchment.

Quantifying the marine radiocarbon reservoir effect, offsets (ΔR), and ΔR variability over time is critical to improving dating estimates of marine samples while also providing a proxy of water mass dynamics. In the northeastern Pacific, where no high-resolution time series of ΔR has yet been established, we sampled radiocarbon (14C) from exactly dated growth increments in a multicentennial chronology of the long-lived bivalve, Pacific geoduck (Paneopea generosa) at the Tree Nob site, coastal British Columbia, Canada. Samples were taken at approximately decadal time intervals from 1725 CE to 1920 CE and indicate average ΔR values of 256 ± 22 years (1σ) consistent with existing discrete estimates. Temporal variability in ΔR is small relative to analogous Atlantic records except for an unusually old-water event, 1802–1812. The correlation between ΔR and sea surface temperature (SST) reconstructed from geoduck increment width is weakly significant (r2 = .29, p = .03), indicating warm water is generally old, when the 1802–1812 interval is excluded. This interval contains the oldest (–2.1σ) anomaly, and that is coincident with the coldest (–2.7σ) anomalies of the temperature reconstruction. An additional 32 14C values spanning 1952–1980 were detrended using a northeastern Pacific bomb pulse curve. Significant positive correlations were identified between the detrended 14C data and annual El Niño Southern Oscillation (ENSO) and summer SST such that cooler conditions are associated with older water. Thus, 14C is generally relatively stable with weak, potentially inconsistent associations to climate variables, but capable of infrequent excursions as illustrated by the unusually cold, old-water 1802–1812 interval.

Tsunamis are huge disasters that can significantly damage benthic organisms and the sea-bottom environment in coastal areas. It is of great ecological importance to understand how benthic ecosystems respond to such destructive forces and how individual species are affected. Investigating the effect of such disasters on animals that are seldom caught alive is particularly difficult. Bivalve mollusks are especially suitable for investigating how a tsunami affects coastal benthic species because they preserve an environmental record in their shells that can be extended back in time by crossdating the records of multiple individuals. Here we studied dead shells of Mercenaria stimpsoni, a long-lived clam, and precisely determined the time of death by using nuclear bomb–induced radiocarbon (bomb-14C) and by counting annual growth increments. First, a quasi-continuous, regional bomb-14C record was created by analyzing the shells of 6 live-caught M. stimpsoni individuals. Then 27 dead shells collected from the seafloor of Funakoshi Bay were 14C-dated and analyzed. The results showed that the huge tsunami that struck northeastern Japan on 11 March 2011 caused mass mortality of this bivalve in Funakoshi Bay. Nine of the 27 clams died during the March 2011 tsunami, probably by starvation after burial by tsunami deposits or exposure above the seafloor as a result of sediment liquefaction during the earthquake. The dating method used in this study can help us understand how long-lived marine organisms with low population density are affected by huge natural disasters such as a tsunami.

In shell-secreting molluscs, age and growth rate of individuals and hence their performance can normally be measured using growth lines that are deposited in the shell throughout their lives. An annual periodicity of growth line formation of the warm-water limpet Patella depressa was established using marked and recaptured individuals from north Wales, UK. Length at age from suitably prepared shell sections was determined in limpets from non-range-edge populations and at two range edges, where different demographic attributes have been recorded. Individuals collected from their poleward range-edge in north Wales were older when compared with individuals at their range-edge in southern England. Shells collected from southern England were characterized by rapid growth with most individuals reaching >30 mm in maximum length by the fourth or fifth year, contrasting with those from north Wales, where most shells only reached this size at 7–10 years of age. Von Bertalanffy growth coefficients (K-values) were negatively related to P. depressa density, showing faster growth in lower total densities of both P. depressa and Patella vulgata combined. Higher intra-specific effects on K-values were found in P. depressa compared with its congener P. vulgata, with stronger effects in north Wales than in southern England. These results confirm differences in population patterns and individual traits between the two leading edges of P. depressa. Understanding annual growth in P. depressa over large scales could help to disentangle the processes determining differences in shell growth and age structure seen at the two range edges of this limpet species.

We recently started a systematic approach to determine the reservoir age in southeast Arabia and its dependence on mollusk species and their environment. This part of the study concentrates on local reservoir age and stable isotopes of the lagoonal species Terebralia palustris and Anadara uropigimelana at Khor Kalba, Oman Sea. Environmental and nutritive influences on mollusks are reflected in the radiocarbon and stable isotope signal. We found a local reservoir age of A. uropigimelana of about 940 yr and that of T. palustris as 800 yr. Sclerochronological analyses yielded information about seasonality of growth and death in A. uropigimelana. The modern shell of Periglypta reticulata shares food resources and habitat with Anadara sp., of which we did not find a modern specimen. It provided information on response to changes in temperature in the lagoonal system needed for suitability as reflecting climatic conditions. We were interested in carbon pathways of the mangrove in Kalba and a mangrove planted anew on a former mangrove sediment in Ajman. Being an obvious source of charcoal and food of T. palustris makes this information necessary. Further analyses will be performed to interpret changes in reservoir age in complex lagoonal systems as reaction to environmental variability.

Shell aragonite δ180 values of unionid freshwater mussels are applied as a proxy for past river discharges in the rivers Rhine and Meuse, using a set of nine shells from selected climatic intervals during the late Holocene. A single Meuse shell derives from the Subboreal and its δ180 values are similar to modern values. The Rhine specimens represent the Subboreal, the Roman Warm Period and the Medieval Warm Period (MWP). These shells also show averages and ranges of aragonite δ180 values similar to modern specimens. This indicates that environmental conditions such as Rhine river dynamics, Alpine meltwater input and drought severity during these intervals were similar to the 20th century. These shells do not record subtle centennial to millennial climatic variation due to their relatively short lifespan and the large inter-annual and intra-seasonal variation in environmental conditions. However, they are very suitable for studying seasonal to decadal scale climate variability. The two shells with the longest lifespan appear to show decadal scale variability in reconstructed water δ180 values during the MWP, possibly forced by the North Atlantic Oscillation (NAO), which is the dominant mode of variability influencing precipitation regimes over Europe.

Metabolism and growth rate of the hard clam, Mercenaria mercenaria, were investigated in a population invasive to Southampton Water, southern England. An individual metabolic model expressed as a function of soft tissue dry mass was fitted to data of 18 individuals (log (VO2) = −1.952 + 0.543 • log (DM); F1,16 = 201.18, P < 0.001, r2 = 0.926). A von Bertalanffy growth function was fitted to 227 size-at-age data pairs of 18 individuals (Ht = 80.13 • (1 − e−0.149 • (t−0.542)); r2 = 0.927). Individual age-specific somatic production was calculated, demonstrating increase with age to a maximum of 3.88 kJ y−1 at ten years old followed by decrease, and individual age-specific annual respiration was calculated, demonstrating asymptotic increase with age to 231.37 kJ y−1 at 30 years old. Results found here lie within the physiological tolerances reported across the biogeographical range, suggesting that the species' biogeographical limitation in the UK to Southampton Water results from ecological rather than physiological factors.

Fin spine ageing is the most common technique used to estimate age and growth parameters of large pelagic billfishes from the families Istiophoridae and Xiphiidae. The most suitable methods for processing and interpreting these calcified structures for age estimation have not been clearly defined. Methodological differences between unvalidated ageing studies are of particular concern for highly migratory species because multiple researchers in different regions of the world may conduct age estimates on the same species or stock. This review provides a critical overview of the methods used in previous fin spine ageing studies on billfishes and provides recommendations towards the development of a standardized protocol for estimating the age of striped marlin, Kajikia audax and white marlin, Kajikia albida. Three on-going fin spine ageing studies from Australia, Hawaii, and Florida are used to illustrate some of the considerations and difficulties encountered when developing an ageing protocol for highly migratory fish species. Particular areas of concern that may influence age and growth estimates included differences in fin spine selection, sectioning methods, criteria for identifying and measuring annuli, distinguishing false annuli, validation procedures, identification of the first annulus, and methods used to replace annuli lost due to vascularization of the fin spine core.

A growing body of literature is using sclerochronological information to infer past climates. Sclerochronologies are based on series of skeletal growth records of molluscs that have been correctly aligned in time. Incremental series are obtained from a number of shells to assess the temporal control and improve the climate signal in the final chronology. Much of the sclerochronological theory has been adopted from tree-ring science, due to the longer tradition and more firmly established concepts of chronology construction in dendrochronology. Compared to tree-ring studies, however, sclerochronological datasets are often characterized by relatively small sample size. Here we evaluate how effectively palaeoclimatic signal can be extracted from such a suite of samples. In so doing, the influences of the very basic methods that are applied in nearly every sclerochronological study to remove the non-climatic growth variability prior to palaeoclimatic interpretations, are ranked by their capability to amplify the desired signal. The study is performed in the context of six shells that constitute a bicentennial growth record from annual shell increments of freshwater pearl mussel. It was shown that when the individual series were detrended using the models set by the mean or the median summary curves for ageing (that is, applying Regional Curve Standardization, RCS), instead of fitting the ageing mode statistically to each series, the resulting sclerochronology displayed more low-frequency variability. Consistently, the added low-frequency variability evoked higher proxy–climate correlations. These results show the particular benefit of using the RCS method to develop sclerochronologies and preserve their low-frequency variations. Moreover, calculating the ageing curve and the final chronology by median, instead of mean, resulted in an amplified low-frequency climate signal. The results help to answer a growing need to better understand the behaviour of the sclerochronological data. In addition, we discuss the pitfalls that may potentially disrupt palaeoclimate signal detection in similar sclerochronological studies. Pitfalls may arise from shell taphonomy, water chemistry, time-variant characters of biological growth trends and small sample size.

L'estimation de l'âge de Prochilodus nigricans Agassiz, 1829 est réalisée à partir de 840 poissons pêchés de 1983 à 1987 dans les principaux milieux du réseau hydrographique de la rivière Mamoré (Béni, Bolivie). Diverses préparations et observations de pièces calcifiées (écailles, otolithes, rayon épineux dorsal et os operculaire), ainsi que les comparaisons de plusieurs lectures, ont permis de choisir l'écaille et ses marques de croissance pour estimer l'âge. Les pertes d'écailles, entraînant la présence de très nombreuses écailles régénérées macrocentriques, paraissent dues à l'abondance des poissons lépidophages du genre Roeboides. Les marques principales de croissance sur les écailles microcentriques sont décrites, ainsi que les principales anomalies ayant engendré des difficultés de lecture. La validation des marques retenues est faite directement par la mesure de la distance séparant la dernière marque du bord de l'écaille, et indirectement, pour les jeunes nés dans l'année, par la comparaison de leur distribution de longueurs à la capture avec celle obtenue par rétrocalcul au moment de l'apparition de la première marque, Pour tous les groupes d'âge, la formation des marques principales de croissance sur les écailles est influencée par le niveau des eaux dans le Mamoré : la formation des annulus se produit une fois par an lors de l'étiage ou au début de la crue (septembre à décembre), sur une grande majorité des individus. La date moyenne de naissance étant fixée au 15 février, l'âge peut étre connu en général avec une précision de l'ordre du mois. Pour l'étude de l'âge chez une espèce inconnue, le choix préliminaire du type de pièce à prélever est orienté â la fois par les résultats des tests de lectures comparées et par des considérations pratiques.