Publications

Numerous studies have compared the rates of primary production using various techniques at specific locations and times. However, these comparisons are local and cannot be used to compare or scale rates of primary production using different methods across ocean basins or seasonal time scales. Here, we quantify the range in rates of primary production derived using different techniques and provide equations that allow conversions of estimates between different methods. We do so on the basis of a compilation of data on volumetric estimates of primary production rates concurrently estimated with at least two different methods. We observed that the comparison of estimates of marine phytoplankton primary production derived from different methods reveals very large variations between methods. The highest primary production estimates are derived using the 18O method, which may provide the best and more generally applicable estimate of gross primary production. The regression equations presented in this work provide the best available approach to convert data across methods and therefore integrate and synthesize available and future data derived using different methods.

Molecular analyses of bacteria associated with photosynthetic organisms are often confounded by coamplification of the chloroplastidial 16S rDNA with the targeted bacterial 16S rDNA. This major problem has hampered progress in the characterization of bacterial communities associated to photosynthetic organisms and has limited the full realization of the potential offered by the last generation of metagenomics approaches. A simple and inexpensive method is presented, based on ethanol and bleach treatments prior to extraction, to efficiently discard a great part of chloroplastidial DNA without affecting the characterization of bacterial communities through pyrosequencing. Its effectiveness for the description of bacterial lineages associated to the green alga Caulerpa taxifolia (M. Vahl) C. Agardh was much higher than that of the preexisting enrichment protocols proposed for plants. Furthermore, this new technique requires a very small amount of biological material compared to the other current protocols, making it more realistic for systematic use in ecological and phylogenetic studies and opening promising prospects for metagenomics of green algae, as shown by our data.

Marine ecosystems are increasingly exposed to stress factors of anthropogenic origin that change their function, structure and services they deliver society. Climate change occurs simultaneously with other changes in the environment acting jointly in a context of global environmental change. For oceanic phytoplankton communities, the research conducted so far has identified stress factors associated with global change and their impact individually (warming, acidification, increased UVB radiation, pollutants). But when several stressors act simultaneously interactions and responses are not equal to the sum of individual impacts, but may have synergistic effects (the effects are multiplied) or antagonistic (cancel out the effects) that hinder predictions of the vulnerability of ecosystems to global change. Here we will examine the vulnerability of oceanic primary producers to the accumulation of different stressors associated with global change. The trend for autotrophic picoplankton to increase with temperature in the ocean has led to predictions that autotrophic picoplankton abundance will increase with warming. However, it is documented a trend towards a decline in productivity, due to declined autotroph biomass and production with warming and the associated stratification in the subtropical ocean. Models predicting an increase in abundance are in contradiction with the reported decrease in productivity in several oceanic areas, and associate oligotrophication. Here we perform a global study to analyze the relationships of autotrophic picoplankton with oceanic temperature, nutrients, underwater light and ultraviolet B (UVB) radiation, and productivity. We built a model to project the future changes of autotrophic picoplankton considering multiple environmental changes in future climate scenarios for the subtropical gyres. We considered increased water temperature, and associated changes in productivity and underwater light and UVB. The model show that warming and the decrease in water productivity, with the associated increase in photosynthetic active radiation and UV-B radiation at depth, are expected to result in a decline by 18 to 42 % in the abundance of autotrophic picoplankton. We also predict an increase in the importance of deep blooms at moderate warming, that models based solely in temperature changes failed to predict. We will examine also the vulnerability of oceanic primary producers to the accumulation of different stressors associated with global change as warming, increased UVB radiation and persistent organic pollutants, and explore whether there are synergistic and antagonistic responses of due to join stresses impacting them.

Boat noise has been shown to distract and cause harm to many marine organisms. Most of the study effort has focused on fish & marine mammals, even though invertebrates represent over 92 % of all marine life. The few studies conducted on invertebrates have demonstrated clear negative effects of anthropogenic noise pollution. The small giant clam Tridacna maxima and the spider conch Lambis lambis are two invertebrate species which play key roles in coral reef ecosystems, and are little studied for the effects of noise disturbance. T. maxima functions as prey for many fish species, contributes up to 9 % of the reef's calcium carbonate budget, and plays a role in nutrient cycling. The herbivorous strombid L. lambis can occur in large numbers on reef flats and is prey for other snails and several elasmobranchs. Using two case study reefs, we show that both boat noise and biotic sounds are prominent sound sources in Red Sea reef habitats. In-situ controlled exposure experiments were conducted on two shallow central Red Sea reefs, where Daily Diary smart tags were used to measure the reactions of T. maxima and L. lambis during underwater playback of boat noise and ambient reef sound. Both macroinvertebrates exhibited behavioral changes during the boat noise treatment. Our results suggest that L. lambis and T. maxima individuals may spend energy averting the invisible "threat" of boat noise, rather than feeding or staying open for symbiotic algae to perform photosynthesis, in the case of T. maxima. As boat noise is prevalent on Red Sea reefs, invertebrates may be affected on a large scale in the Red Sea.

Tracking data have led to evidence-based conservation of marine megafauna, but a disconnect remains between the many thousands of individual animals that have been tracked and the use of these data in conservation and management actions. Furthermore, the focus of most conservation efforts is within Exclusive Economic Zones despite the ability of these species to move thousands of kilometres across multiple national jurisdictions. To assist the goal of the United Nations General Assembly's recent effort to negotiate a global treaty to conserve biodiversity on the high seas, we propose the development of a new frontier in dynamic marine spatial management. We argue that a global approach combining tracked movements of marine megafauna and human activities at-sea, and using existing and emerging technologies (e.g., through new tracking devices and big data approaches) can be applied to deliver near real-time diagnostics on existing risks and threats to mitigate global risks for marine megafauna. With technology developments over the next decade expected to catalyse the potential to survey marine animals and human activities in ever more detail and at global scales, the development of dynamic predictive tools based on near real-time tracking and environmental data will become crucial to address increasing risks. Such global tools for dynamic spatial and temporal management will, however, require extensive synoptic data updates and will be dependent on a shift to a culture of data sharing and open access. We propose a global mechanism to store and make such data available in near real-time, enabling a holistic view of space use by marine megafauna and humans that would significantly accelerate efforts to mitigate impacts and improve conservation and management of marine megafauna.

The abundance of anthropogenic debris dispersed in the environment is exponentially growing, raising concerns about marine life and human exposure to microplastics. Microfibers are the most abundant microplastic type in the environment. However, recent research suggests that most microfibers dispersed in the environment are not made of synthetic polymers. In this work, we systematically tested this assumption by determining the man-made or natural origin of microfibers found in different environments, including surface waters, sediments at depths >5000 m and highly sensitive habitats like mangroves and seagrass, and treated water using stimulated Raman scattering (SRS) microscopy. Our findings show that ¾