The effects of environment on Arctica islandica shell formation and architecture

Mollusks record valuable information in their hard parts that reflect ambient environmental conditions. For this reason, shells can serve as excellent archives to reconstruct past climate and environmental variability. However, animal physiology and biomineralization, which are often poorly understood, can make the decoding of environmental signals a challenging task. Many of the routinely used shell-based proxies are sensitive to multiple different environmental and physiological variables. Therefore, the identification and interpretation of individual environmental signals (e.g., water temperature) often is particularly difficult. Additional proxies not influenced by multiple environmental variables or animal physiology would be a great asset in the field of paleoclimatology. The aim of this study is to investigate the potential use of structural properties of Arctica islandica shells as an environmental proxy. A total of 11 specimens were analyzed to study if changes of the microstructural organization of this marine bivalve are related to environmental conditions. In order to limit the interference of multiple parameters, the samples were cultured under controlled conditions. Three specimens presented here were grown at two different water temperatures (10 and 15 °C) for multiple weeks and exposed only to ambient food conditions. An additional eight specimens were reared under three different dietary regimes. Shell material was analyzed with two techniques; (1) confocal Raman microscopy (CRM) was used to quantify changes of the orientation of microstructural units and pigment distribution, and (2) scanning electron microscopy (SEM) was used to detect changes in microstructural organization. Our results indicate that A. islandica microstructure is not sensitive to changes in the food source and, likely, shell pigment are not altered by diet. However, seawater temperature had a statistically significant effect on the orientation of the biomineral. Although additional work is required, the results presented here suggest that the crystallographic orientation of biomineral units of A. islandica may serve as an alternative and independent proxy for seawater temperature

Interactive effects of temperature and food availability on the growth of Arctica islandica juveniles

Shell and tissue growth of Arctica islandica juveniles

The effects of environment on <i>Arctica islandica</i> shell formation and architecture

Mollusks record valuable information in their hard parts that reflect ambient environmental conditions. For this reason, shells can serve as excellent archives to reconstruct past climate and environmental variability. However, animal physiology and biomineralization, which are often poorly understood, can make the decoding of environmental signals a challenging task. Many of the routinely used shell-based proxies are sensitive to multiple different environmental and physiological variables. Therefore, the identification and interpretation of individual environmental signals (e.g., water temperature) often is particularly difficult. Additional proxies not influenced by multiple environmental variables or animal physiology would be a great asset in the field of paleoclimatology. The aim of this study is to investigate the potential use of structural properties of Arctica islandica shells as an environmental proxy. A total of 11 specimens were analyzed to study if changes of the microstructural organization of this marine bivalve are related to environmental conditions. In order to limit the interference of multiple parameters, the samples were cultured under controlled conditions. Three specimens presented here were grown at two different water temperatures (10 and 15 °C) for multiple weeks and exposed only to ambient food conditions. An additional eight specimens were reared under three different dietary regimes. Shell material was analyzed with two techniques; (1) confocal Raman microscopy (CRM) was used to quantify changes of the orientation of microstructural units and pigment distribution, and (2) scanning electron microscopy (SEM) was used to detect changes in microstructural organization. Our results indicate that A. islandica microstructure is not sensitive to changes in the food source and, likely, shell pigment are not altered by diet. However, seawater temperature had a statistically significant effect on the orientation of the biomineral. Although additional work is required, the results presented here suggest that the crystallographic orientation of biomineral units of A. islandica may serve as an alternative and independent proxy for seawater temperature

The effects of environment on Arctica islandica shell formation and architecture

Mollusks record valuable information in their hard parts that reflect ambient environmental conditions. For this reason, shells can serve as excellent archives to reconstruct past climate and environmental variability. However, animal physiology and biomineralization, which are often poorly understood, can make the decoding of environmental signals a challenging task. Many of the routinely used shell-based proxies are sensitive to multiple different environmental and physiological variables. Therefore, the identification and interpretation of individual environmental signals (e.g., water temperature) often is particularly difficult. Additional proxies not influenced by multiple environmental variables or animal physiology would be a great asset in the field of paleoclimatology. The aim of this study is to investigate the potential use of structural properties of Arctica islandica shells as an environmental proxy. A total of 11 specimens were analyzed to study if changes of the microstructural organization of this marine bivalve are related to environmental conditions. In order to limit the interference of multiple parameters, the samples were cultured under controlled conditions. Three specimens presented here were grown at two different water temperatures (10 and 15 °C) for multiple weeks and exposed only to ambient food conditions. An additional eight specimens were reared under three different dietary regimes. Shell material was analyzed with two techniques; (1) confocal Raman microscopy (CRM) was used to quantify changes of the orientation of microstructural units and pigment distribution, and (2) scanning electron microscopy (SEM) was used to detect changes in microstructural organization. Our results indicate that A. islandica microstructure is not sensitive to changes in the food source and, likely, shell pigment are not altered by diet. However, seawater temperature had a statistically significant effect on the orientation of the biomineral. Although additional work is required, the results presented here suggest that the crystallographic orientation of biomineral units of A. islandica may serve as an alternative and independent proxy for seawater temperature.This article is published as Milano, S., Nehrke, G., Wanamaker, A.D., Ballesta-Artero, I., Brey, T., and Schöne, B.R., (2017) The effects of environment on Arctica islandica shell formation and architecture. Biogeosciences, 14, 1577-1591. doi: 10.5194/bg-14-1577-2017. Posted with permission.</p

Energetics of the extremely long-living bivalve Arctica islandica based on a Dynamic Energy Budget model

The ocean quahog Arctica islandica is the longest–living mollusk on Earth with a lifespan of at least 500 years. The slow senescence of this bivalve has promoted a great interest in its metabolic strategy. A dynamic energy budget (DEB) model was applied to describe how this species allocates its energy to maintenance, growth, maturation, and reproduction in a variable environment. We studied the relationship between A. islandica growth, lifespan, and food availability at eight different locations in the North Atlantic Ocean. Our results indicate that A. islandica's extreme longevity arises from its low somatic maintenance cost ṗM and low ageing acceleration h¨a, but there was not a direct relationship between food availability and lifespan in these A. islandica locations. Monkey Bank (North Sea), Iceland, and Ingøya (northern Norway) had the highest food availability estimates of all the localities but did not have the lowest longevities, in contrast to the theory of caloric restriction

Factors underlying the recovery potential of littoral seagrass in the Dutch Wadden Sea

In de Waddenzee komen twee soorten zeegras voor, namelijk klein zeegras (Zostera noltii) en groot zeegras (Zostera marina). Beide soorten kunnen een eenjarige en een meerjarige levenscyclus vertonen, waarbij ze respectievelijk met zaden en wortelstokken de winter overleven. Na een periode van zeer lage abundantie, als gevolg van ziekten in de jaren dertig en eutrofiëring in de jaren tachtig, lijkt het zeegras in de noordelijke delen van de trilaterale Waddenzee zich te herstellen, onder meer als het resultaat van een verbetering van de waterkwaliteit. In de zuidelijke delen van de Waddenzee zijn zeegrasvelden echter nog schaars en hebben ze een lage dichtheid. Hoewel zeegras in de Nederlandse Waddenzee enig herstel leek te hebben doorgemaakt, is het huidige oppervlak van de zeegrasvelden (ca. 3 km2) nog steeds maar een fractie (<3%) van het oppervlak dat geschikt lijkt te zijn voor het voorkomen van zeegras (ongeveer 130 km2). Dit vraagt om nader onderzoek naar omgevingsfactoren die de uitbreiding van zeegras in de Nederlandse Waddenzee mogelijk beperken