Abstract The relationship between energy reserves of cold-water corals (CWCs) and their physiological performance remains largely unknown. In addition, it is poorly understood how the energy allocation to different metabolic processes might change with projected decreasing food supply to the deep sea in the future. This study explores the temporal and spatial variations of total energy reserves (proteins, carbohydrates and lipids) of the CWC Desmophyllum dianthus and their correlation with its calcification rate. We took advantage of distinct horizontal and vertical physico-chemical gradients in Comau Fjord (Chile) and examined the changes in energy reserves over one year in an in situ reciprocal transplantation experiment (20 m vs. 300 m and fjord head vs. mouth). Total energy reserves correlated positively with calcification rates. The fast-growing deep corals had higher and less variable energy reserves, while the slower-growing shallow corals showed pronounced seasonal changes in energy reserves. Novel deep corals (transplanted from shallow) were able to quickly increase both their calcification rates and energy reserves to similar levels as native deep corals. Our study shows the importance of energy reserves in sustaining CWC growth in spite of aragonite undersaturated conditions (deep corals) in the present, and potentially also future ocean.
Abstract. Throughout the last few decades and in the near future CO2–induced ocean acidification is potentially a big threat to marine calcite-shelled animals (e.g., brachiopods, bivalves, corals and gastropods). Despite the great number of studies focusing on the effects of acidification on shell growth, metabolism, shell dissolution and shell repair, the consequences on biomineral formation remain poorly understood, and only few studies addressed contemporarily the impact of acidification on shell microstructure and geochemistry. In this study, a detailed microstructure and stable isotope geochemistry investigation was performed on nine adult brachiopod specimens of Magellania venosa (Dixon, 1789), grown in the natural environment as well as in controlled culturing experiments at different pH conditions (ranging 7.35 to 8.15 ± 0.05) over different time intervals (214 to 335 days). Details of shell microstructural features, such as thickness of the primary layer, density and size of endopunctae and morphology of the basic structural unit of the secondary layer were analysed using scanning electron microscopy (SEM). Stable isotope compositions (δ13C and δ18O) were tested from the secondary shell layer along shell ontogenetic increments in both dorsal and ventral valves. Based on our comprehensive dataset, we observed that, under low pH conditions, M. venosa produced a more organic-rich shell with higher density of and larger endopunctae, and smaller secondary layer fibres, when subjected to about one year of culturing. Also, increasingly negative δ13C and δ18O values are recorded by the shell produced during culturing and are related to the CO2–source in the culture setup. Both the microstructural changes and the stable isotope results are similar to observations on brachiopods from the fossil record and strongly support the value of brachiopods as robust archives of proxies for studying ocean acidification events in the geologic past.
La region de los fiordos del sur de Chile alberga tres especies de corales azooxantelados (Cnidaria: Anthozoa: Scleractinia) capaces
de vivir a pocos metros de profundidad. Estas especies corresponden a Desmophyllum dianthus, Caryophyllia huinayensis y
Tethocyathus endesa, las cuales representan una oportunidad unica para el estudio in situ de estas comunidades. El aumento
en la deforestacion asi como el elevado numero de instalaciones acuicolas en esta region generan un impacto en los sistemas
de sedimentos de la zona, razon por la cual se realizo un experimento en laboratorio para evaluar los efectos potenciales de un
incremento en las tasas sedimentarias en estos organismos. Se sometio a los corales a tasas de sedimentacion de 16, 164, 698 y 995
mm ano-1 y se estudiaron las respuestas conductuales (apertura de los polipos) y fisiologicas (consumo de oxigeno y concentracion
de lactato). Tethocyathus endesa, a diferencia de las otras dos especies, presento un aumento significativo en el numero de
polipos abiertos y escasa variacion en el consumo de oxigeno al ser sometido a mayores tasas sedimentarias, indicando una menor
sensibilidad a la sedimentacion en comparacion con las otras dos especies. Desmophyllum dianthus aumento significativamente
su consumo de oxigeno al ser sometido a una tasa sedimentaria de 995 mm ano-1, lo cual se explicaria por la necesidad de invertir
energia en mecanismos activos de limpieza. Caryophyllia huinayensis, por su parte, disminuyo significativamente su consumo
de oxigeno al ser sometida a tasas sedimentarias de 164 y 698 mm ano-1, presumiblemente en espera de mejores condiciones
ambientales. El contenido de lactato en los tejidos de estos organismos no presento diferencias significativas entre los distintos
tratamientos. Los resultados indican que un aumento en la sedimentacion en la region tiene el potencial de alterar la conducta y
metabolismo de las especies de corales de agua fria presentes en el area, lo cual podria resultar perjudicial para estas comunidades.
Fundacion San Ignacio del Huinay, Centro de Investigacion y Desarrollo Tecnologico en Algas (CIDTA) y proyectos CARO PCCI2012060
(proyecto bilateral de BMBF-CONICYT), Fondecyt 1150843, Fondef D10|1038 y Fondecyt 1120469.
Donacides are distributed at sandy beaches all over the world except the Polar Regions, whereas the number of total species is 64. Many species of this family are demonstrating a valuable source for the artisanal fisheries. D. marincovichi and D. obesulus inhabit beaches from Northern Chile to Northern Ecuador in dense populations. The taxonomy of D. marincovichi and D. obesulus are controversially discussed. Sperm morphology is useful for taxonomic identification, frequently applied for mollusk taxonomy. Therefore samples of D. obesulus were taken from a Northern Chilean beach in Arica (Chinchorro) and D. marincovichi sampled in Central Peru south of Lima (Jahuya). Male gonads were elaborated and analyzed by transmission electron microscopy (TEM). Both putative species demonstrate a primitive sperm type, structured in acrosome, nucleus and tail (9+2 axoneme). In both cases the total number of mitochondria is four. The apex of the acrosome of both species shows a characteristic arrowhead, which was not observed from other species of this family yet. No differences in sperm morphology were found between both putative species. This supports our genetic study indicating that we rather deal with one single instead of two distinct Donax species.
Klimavariabilitat auf verschiedenen Zeitskalen tragt masgeblich dazu bei, dass die Ertrage lebender Ressourcen grosen Schwankungen unterliegen. In jungerer Zeit haben menschliche Nutzung und schadliche anthropogene Einwirkungen auf marine und limnische Okosysteme ein solches Ausmas angenommen, dass die Ertrage freilebender Ressourcen zuruckgehen; Reserven sind kaum noch vorhanden, und die Erkenntnis setzt sich durch, dass die Ozeane nicht unerschopflich sind. Bei den Bestandseinbruchen konnen naturliche Effekte des Klimawandels und durch den Menschen verursachte Auswirkungen sich aufsummieren wie im Fall des El Nino, der PDO und der Uberfischung von Schwarmfischen, deren Einzelwirkungen nur schwer zu entschlusseln sind. Zu direkten Wirkungen auf die Bestande, zum Beispiel durch den Fischfang, kommen indirekte Effekte uber die Vernichtung komplexer Lebens-raume und die Reduktion der Biodiversitat. Verbesserungen im Management, vor allem ein noch starkerer okosystemarer Bezug aller Masnahmen und die Einrichtung von Schutzgebieten sind notwendig, konnen die Talfahrt aber allenfalls bremsen. Nennenswerte Zuwachsraten in der Produktion lebender Ressourcen sind kunftig nur aus der Aquakultur zu erwarten, die ebenfalls erhebliche Nebenwirkungen mit sich bringt. Dennoch gibt es zu einer okologisch angepassten, umweltfreundlichen und nachhaltigen Aquakultur keine Alternative.
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