ALBERT

Description: The Chilean fjord region, situated between 42 and 56 °S, forms one of the most ragged shorelines and belongs to the ecologically and biogeographically least understood marine regions of the world. A labyrinth of fjords, channels, and islands extends over 240,000 km2 and creates a coastline of more than 80,000 km. Due to strong abiotic gradients, numerous habitats are created, which are further diversified by temporal dynamics (tidal cycle, seasonal changes in precipitation, temperature, radiation, etc.). The region is a biodiversity hotspot hosting unique and fragile ecosystems. Among the species living here, several are species forming habitats in the ecosystem. These organisms can reach high densities conforming the so-called marine animal forests. Examples are marine animal forests dominated by cold-water stony corals, gorgonians, hydrocorals, brachiopods, polychaetes, giant barnacles, sponges, and ascidians. Many of these communities have been discov- ered only recently. There is also a singular characteristic in this area: exceptionally low pH levels of the waters of Patagonian fjords provide the opportunity to study calcifying organisms in an environment with pH conditions in the same range as the ones predicted by the IPCC for the world oceans in 2100. Despite the scarce ecological and biogeographical knowledge of this area, it encounters an unparalleled economic development including high-impact industry-scale salmonid farming, ambitious infrastructure and industrialization projects, and increasing extractive activities. Baseline research on the abiotic and biotic environment of the region is needed to reach sustainability in the use of the marine resources. Management plans including the establishment of marine protected areas to preserve benthic diversity and ecosystem services are urgently needed.

Description: Fiordo Comau in Northern Patagonia, Chile, is home to a wide range of unique habitats and diverse communities of many new and little understood species. At one site in the fiordo, XHuinay, H2S seeps allow for the formation of filamentous chemosynthetic bacteria mats. Here, two scleractinians, Desmophyllum dianthus and Caryophyllia huinayensis, were once abundant on hard substrate below 18m depth. However, a recent mass mortality of D. dianthus occurred while C. huinayensis continues to survive. This pilot study investigates whether the presence of H2S seeps and their associated bacteria have an affect on D. dianthus mortality. We fixed nine D. dianthus individuals and nine C. huinayensis individuals at 25m depth at two sites: XHuinay and Isla Lilihuapi (control) to monitor their survival under actual conditions. If H2S seeps negatively affect Desmophyllum dianthus survival, then we expect to observe deaths of individuals of D. dianthus at XHuinay and the survival of individuals at Isla Lilihuapi. We also expect C. huinayensis to survive at both sites. This experiment is still in progress. However, this preliminary study emphasizes the need for and seeks to prompt further investigation into these scleractinians, their relationship with both biotic and abiotic environmental factors, and specifically their role within the fragile web of Chilean Fiord ecology. El fiordo Comau, en la Patagonia Norte de Chile, da hogar a una gran variedad de hábitats singulares y comunidades diversas de muchas especies nuevas y poco entendidas. En un sitio en el fiordo (X-Huinay) filtraciones de H2S permiten la formación de bacterias quimiosintéticas que crean esteras filamentosas. En este sitio abundaban antes dos escleractinios, Desmophyllum dianthus y Caryophyllia huinayensis, en el sustrato duro abajo de una profundidad de 18m. Sin embargo, una mortalidad masiva de D. dianthus fue detectada recientemente, mientras que C. huinayensis continúa sobreviviendo en este sitio. Este estudio piloto investiga si la presencia de las filtraciones de H2S y las bacterias asociadas están conectadas a la mortalidad de D. dianthus. Nueve individuos de D. dianthus y nueve individuos de C. huinayensis fueron fijados a una profundidad de 25m mediante buceo autónomo en dos sitios: X-Huinay e Isla Lilihuapi (control) para monitorear su supervivencia en condiciones reales. Si las filtraciones de H2S afectan negativamente la supervivencia de D. dianthus, esperamos observar la muerte de individuos de esta especie en X-Huinay pero no en Isla Lilihuapi. Además la expectativa es que no haya mortalidad significativa de C. huinayensis en ninguno de los sitios. Este experimento preliminar aún está en curso, sin embargo hace hincapié en la necesidad de mayores investigaciones de estos escleractinios, sus relaciones con factores ambientales bióticos y abióticos, y específicamente su nicho dentro de la frágil red ecológica de los fiordos chilenos.

Description: Cold-water corals are known to grow much slower than their tropical counterparts. However, this assumption is mainly based on laboratory measurements exposing specimens to conditions that differ from their natural environments. The cosmopolitan scleractinian Desmophyllum dianthus forms dense banks below 18min northern Patagonia, Chile. So as to measure in situ growth rates of this cold-water coral, specimens were collected from two sites, weighed and deployed on holders in their natural headlong orientation at the respective collecting site. Corals exhibited a calcium carbonate (CaCO3) mass increase of 5.44+/-3.45 (mg (cm2 projected calyx area)^-1 day^-1) after 2 weeks, equivalent to a mass gain of 0.25+/-0.18 s.d. % day^-1. In comparison, D. dianthus specimens from the same collection sites maintained in an on-site flow-through aquarium system showed lower growth rates that were third of the in situ rates. In situ CaCO3 precipitation of D. dianthus extrapolated for 1 year (kg m^2 year^-1) displays the same order of magnitude as reported for massive growing tropical scleractinians, e.g. Porites sp.

Description: The fibrous calcite layer of modern brachiopod shells is a hybrid composite material and forms a substantial part of the hard tissue. We investigated how cells of the outer mantle epithelium (OME) secrete calcite material and generate the characteristic fibre morphology and composite microstructure of the shell. We employed AFM, FE-SEM, and TEM imaging of embedded/etched, chemically fixed/decalcified and high-pressure frozen/freeze substituted samples. Calcite fibres are secreted by outer mantle epithelium (OME) cells. Biometric analysis of TEM micrographs indicates that about 50% of these cells are attached via hemidesmosomes to an extracellular organic membrane present at the proximal, convex surface of the fibres. At these sites, mineral secretion is not active. Instead, ion transport from OME cells to developing fibres occurs at regions of closest contact between cells and fibres, however only at sites where the extracellular membrane at the proximal fibre surface is not developed yet. Fibre formation requires the cooperation of several adjacent OME cells. It is a spatially and temporally changing process comprising of detachment of OME cells from the extracellular organic membrane, mineral secretion at detachment sites, termination of secretion with formation of the extracellular organic membrane, and attachment of cells via hemidesmosomes to this membrane.