Dr. Richard Rivkin

Dr. Richard B. Rivkin:

Richard Rivkin is a University Research Professor at the Ocean Sciences Centre (OSC), Memorial University of Newfoundland and has internationally recognised research programmes studying the microbial food web dynamics and their influence on the cycling of organic material on ocean-climate interactions. Dr. Rivkin held faculty positions at University of Maryland (1983-1991) and The Johns Hopkins University (1978-1983). While in the United States, he studied the physiological ecology of phytoplankton and microbial food web processes in temperate and tropical oceans and in the Antarctic. Upon his move to Canada in 1991, he expanded the scope of his research to assessing and modelling the role of microbes in controlling oceanic biogeochemistry at global scales, and their effects on ocean-climate interactions. Simply stated, his research is at the critical interface between microbial ecology, ocean biogeogeochemistry and climate!

Dr. Rivkin has studied various aspects of biological oceanographic processes and global ocean ecology for almost 30 years. Throughout his scientific career, a fundamental component in all his research has been careful hypothesis formulation and testing with a combination of laboratory and field (and in the last decade, modeling) studies. This approach allows field studies to be evaluated within the context of what is understood about the physiology of the organisms, and permits the more realistic representation of food web interactions and biogeochemical processes. The long-term goal of his research is to understand and predict the responses of organisms and food webs to climate forcings. In order to achieve these goals, it is necessary to understand the "rules” governing relationships and interactions between organisms and the environment. Moreover, since it is critical to know both "why" as well as "how" processes change, it is necessary to understand how the relationships change with evolving environmental or climatic conditions.

To achieve these research goals, Dr. Rivkin lead field teams on eight large-scale research expeditions to the Antarctic, on numerous ship-based missions in the North Atlantic, and in the Sargasso and Caribbean Seas, and has lead or co-lead several Canadian climate-related research programs in the Gulf of St. Lawrence, the Northeast Subarctic Pacific, the Northwest North Atlantic, in the Canadian Arctic and in Newfoundland coastal waters. In addition to these “basic” research programs, he has had several funded programs in “applied” research areas such as the effects of the introduction of aquatic invasive species to Canadian waters, the effects shellfish aquaculture and offshore oil production on environmental integrity and ecosystem carrying capacity. The results of these studies have contributed significantly to our understanding of the biological mediation of the ocean-atmospheric transfer of CO2. For example, his work on environmental control on microbial carbon cycling has been successfully incorporated into several conceptual and numerical models to better understand water column carbon remineralization, export and sequestration. Related work, using large scale data analyses, has also shown the the central role of microbial activity in controlling the export of biogenic carbon to depth or to higher trophic levels, and ultimately the CO2 exchange between atmosphere and ocean.

In addition Dr. Rivkin is also studying processes at the molecular- to individual- organism-scale and relating these studies to global-scale events. His laboratory has assessed the relationships between the structure and biodiversity of the bacterial assemblage, and the physiological and ecological characteristics of the microbial community in an attempt to untangle some fundamental ecological and evolutionary questions! Using a variety of molecular techniques, his research has shown considerable phylogenetic diversity with distinct bacterial biogeographies in the western North Atlantic. These changes in microbial community structure relate to metabolic, ecological and physiological changes in the bacterial community that may reflect environmental and climate forcings. This work has continued to make significant contributions to the parameterization of prognostic ocean-climate models.

Below are listed several of his current research programmes:

Microbial dynamics in the World Ocean (Discovery Grant Programme). This programme combines field measurements with large scale meta-analysis of published information on microbial processes to develop and test hypotheses about the regulation of upper ocean biogeochemical processes including the production, transformation and flux of CO2 in different regions of the World Ocean. Field work is being carried out on both dedicated and opportunity based oceanographic expeditions (in the North Atlantic and Pacific, Arctic, tropical and subtropical South and North Atlantic, etc).

Microbial control on the cycling of trace elements and gases in the Arctic. (SOLAS IPY and Canadian Geotraces IPY; Rivkin). SOLAS characterizes the flux of climate active properties between the ocean and atmosphere whereas Geotraces characterizes the elemental transformation (including those that are influenced by and in turn influence climate processes) of major and trace elements from the surface ocean to ~1000m. In both programmes, I examine and parameterize the role of microbial food webs in the transformation of climate active gases, trace elements, organic and inorganic nutrients.

Microbial dynamics in ballast water: (Canadian Aquatic Invasive Species Network (NSERC Research Network; Rivkin). This programme examines the occurrence, dynamics and survivorship of eukaryotic and prokaryotic microbes in the ballast water that is released into Canadian coastal waters and a comparison with these same groups within Canadian coastal waters.

Hydroelectrical impacts on the Lake Melville Estuary. (DFO/Hydro). Many major impacts of hydroelectric developments come as a consequence of the influence of reservoir formation on the redox conditions of the flooded landscape. One such impact is the increase in microbial methylation of naturally occurring Hg greatly increasing Hg contamination of the reservoir and downstream food webs. I am currently characterizing the microbial food web and quantifying its reliance on riverine-derived organic matter in Lake Melville, the estuary draining the Churchill River, downstream of the current Smallwood Reservoir and future (2009) Lower Churchill Hydroelectric development.