1,721,095 research outputs found
Physiological Responses of Marine Animals Towards Adaptation to Climate ChangesThe Mediterranean Sea
No full textAccording to climatic models, the Mediterranean basin will be one of the regions most affected by the ongoing warming trend and increase in extreme events. The Mediterranean is already one of the most impacted seas in the world, where climate change interacts with many other stressors. Coastal lagoons, in particular, represent critical areas for their importance in terms of land use, economic importance and anthropogenic pressure, and are the main objects of our analysis. A concept emerged in recent studies on climate changes, suggesting that the only environmental signals that matter to an organism are those that the organism experiences. Thus, animal responses may be very different from those expected at a large-scale, and the impacts of climate change can be different according to a number of local/organismal conditions. This review is focused on the effects of climate change-driven factors on animal physiology, considering that physiology bridges the gap between mechanistic molecular understanding and the larger scale ecosystem responses. Indeed, adaptive responses to large-scale perturbations, such as climate change, affect all biological levels but they initially take place at the cellular and individual levels, and are then integrated and translated to upper levels of biological organization. The geochemical features that may influence animals responses are also addressed
Emergence and evolution of early life in the geological environment
No full textBased on our current assumptions, life on Earth started long before 3.5 billion years ago, the age of the oldest (accepted) terrestrial fossils. The issue on how life emerged from a non-living world, however, is still waiting for a solution.
Aside from the many ideas generated by theoretical speculations, however, the issue on origin and evolution of the primordial life can be addressed through some of the oldest environmental conditions still preserved on the terrestrial sedimentary record (and their alleged modern analogues), and other planetary bodies, especially Mars, where rovers, orbiters and spectrometers can deal with unaltered rocks much older than the oldest one preserved on our planet and, perhaps, finally able to reveal some evidence of life
Photoacoustics: a novel application to the determination of photosynthetic efficiency in zooxanthellate hermatypes
No full textWe present here a novel application of photoacoustics to the monitoring and study of the physiological status of zooxanthellate corals. Until now, the method has only been applied in homogeneous phytoplankton cultures and field samples. Corals are among the world's most productive ecosystems because they host symbiotic dinoflagellates (zooxanthellae) that provide them with a large amount of photosynthates for their energy requirements. Coral reefs face unprecedented pressures on local, regional, and global scales due to climate change and anthropogenic disturbances. Responses to such stress are often a decrease in the photosynthetic efficiency of the symbiotic dinoflagellates, as well as bleaching, which involves the mass expulsion of these symbionts or loss of their pigments. Photosynthesis is a sensitive indicator of stress in plants and plays a central role in the nutrition of symbiotic invertebrates. Our aim was to examine the applicability of photoacoustics, developed by us for ecological work with phytoplankton, to the study of symbiotic dinoflagellates in situ. We have determined areal chlorophyll content and light energy storage efficiency with three zooxanthellate coelenterates, two corals and one hydrozoan, hosting symbiotic algae. We also present the effect of temperature elevation on the decrease in photosynthetic efficiency of the symbiotic coral Stylophora pistillata determined by photoacoustics. Our results demonstrate the potential, power, and convenience of photoacoustics in following bleaching-related changes in coral pigmentation, in the photosynthetic energy storage efficiency of corals, and in its usefulness in diagnosing its health in relation to environmental factors, in the example presented here, seawater warming
Evolution of plant-animal interactions
No full textThe evolution of plant–animal interactions goes back to the Early Archean, when the first signals of photosynthesis may have been detected in the Isua Peninsula in Greenland, a phenomenon that is related to the isotopic anomalies of carbon. The first evidence of reliable fossils of photosynthetic microorganisms has been identified by micropaleontologists in the Late Archean and Early Proterozoic. A closely related topic in this geologic time interval is the evolution of trophic relations and metabolic diversification in the microbial world. In the context of the three domains of life, Archea, Bacteria, and Eucarya, the bifurcation of multicellular organisms into plants and animals becomes evident only during the Paleozoic. Cell evolution also leads up to the unicellular dichotomy of autotrophs and heterotrophs. Symbiosis has a strong role to play in the transition to plants and animals in the Phanerozoic. It is timely to focus on the details of evolution in the Cretaceous and Tertiary, where detailed pathways of evolution have been gathered in many geographical regions, including the Karst region of northern Italy. Various experimental techniques have contributed to elucidate the coevolution of plants and animals. A special case of plant–animal interaction is the evolution and dispersal of hominins, including their impact on the ecosystems. A significant development in understanding the evolution of plant–animal interactions is based on the possibility of identifying reliable biomarkers that can characterize its different stages, from the earliest microbes to the extant plants and animals. Such identification of biomarkers labeling different stages of evolution may orient the search for life in the exploration of the Solar System
The resilience of coral reefs and its implications for reef management
No full textOur view of ecosystems has evolved from one emphasizing determinism to an understanding that systems can exhibit dramatic, and often surprising, shifts in state. Perhaps the most well-known shift is the replacement of corals by macroalgae, but others occur when systems experience overwhelming bioerosion or heavy sedimentation. Preventing undesirable shifts in ecosystem state is a key goal of management, particularly given the need to stem the loss of ecosystem services. However, ecosystem shifts have proved difficult to predict because they can occur with little warning. Worse, the symptoms, such as loss of coral, and may be difficult to reverse because ecological feedback processes can constrain recovery. Thus, it is important to understand the factors that drive shifts in ecosystem state and the stability of such states. This is the study of resilience. A resilient reef is usually considered to be one that absorbs disturbances and recovers to a coral-rich state (though other states are also possible). We describe methods to quantify explicitly the resilience of a reef by combining models of a reef’s equilibrial dynamics with its stochastic disturbance regime. In this case, resilience can be calculated as the probability that a reef will avoid shifting to an alternate stable state in a prescribed period of time, given its current state and anticipated disturbance regime. We then discuss the opportunities to “manage for resilience.” Because many acute disturbances, such as coral bleaching, cannot be mitigated directly, the emphasis for management is to enhance processes of coral recovery through the management of watersheds, nutrient-runoff, and grazers. In addition, scientists are beginning to understand spatial patterns of the response of corals to disturbance. Although such research is at an embryonic stage, it promises to play an important role in helping to stratify the interventions of managers across the seascape
The paleoecology of coral reefs
No full textReefs are one of the oldest ecosystems in the world, and coral reefs have had a rich and varied history over hundreds of millions of years. The long-term history of living reef organisms provides an essential window in which to view a number of fundamental evolutionary and ecological processes over extended time frames not available to modern ecology over years or decades. Many of the constituents of modern reefs are calcifying organisms that leave a record of their presence in the fossil record. Thus, coral reef paleoecology has been undertaken on tropical ecosystems worldwide with applications in ecology, evolution, biogeography, extinction risk, conservation and management, and global change biology. Because many reef organisms secrete their calcareous skeletons at or near isotopic equilibrium with ambient seawater, they have also been used to reconstruct environmental conditions over long time frames. The examination of ecological and evolutionary change in the context of environmental variability provides an ideal framework for understanding coral reef paleoecology and placing the modern biodiversity crisis in an historical context
The light from the darkness: Responses of zooxanthellate corals to the underwater light field
No full textA Time-Domain Nuclear Magnetic Resonance Study of Mediterranean Scleractinian Corals Reveals Skeletal-Porosity Sensitivity to Environmental Changes
No full textMediterranean corals are a natural model for studying global warming, as the Mediterranean basin is expected to be one of the most affected regions and the increase of temperature is one of the greatest threats for coral survival. We have analyzed for the first time with Time Domain Nuclear Magnetic Resonance (TD-NMR) porosity and pore-space structure, important aspects of coral skeletons, of two scleractinian corals, Balanophyllia europaea (zooxanthellate) and Leptopsammia pruvoti (non-zooxanthellate), taken from three different sites on the western Italian coast along a temperature gradient. Comparisons have been made with Mercury Intrusion Porosimetry and SEM images. TD-NMR parameters are sensitive to changes of the pore-structure of the two coral species. A parameter, related to the porosity, is larger for Leptopsammia pruvoti than for Balanophyllia europaea, confirming previous non-NMR results. Another parameter representing the fraction of the pore-volume with pore-sizes less than 10-20 um is inversely related, with high statistical significance, to the mass of the specimen, and, for Balanophyllia europaea, to the temperature of the growing site. This effect in the zooxanthellate species, that could reduce its resistance to mechanical stresses, may depend on an inhibition of the photosynthetic process at elevated temperatures and could have particular consequences in determining the effects of global warming on these species
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