to identify the origin of the dissolved, particulate and coarse organic material that is exchanged (i.e., imported and exported) between a coastal wetland (Metzger marsh) and Lake Erie during seiche events and
to investigate the integration of this organic matter into aquatic food webs. Our hypothesis is that seiches allow detrital materials that are produced in the wetland (i.e., macrophyte and algae) to be exported to the lake, where it is consumed by the near-shore organisms.

Adjacent ecosystems are interconnected through the transfer of energy (nutrients, organic matter and species) that involves both biological and nonbiological mechanisms. This notion of "coupled systems" has been successfully applied to evaluate the exchange of energy between riparian systems and rivers during floods, or between salt marshes and coastal waters during tides. Despite the fact that coastal wetlands of large lakes are also hydrologically connected to lakes through wind-driven seiches (e.g., periodic oscillations with irregular amplitudes of lake water level), little information regarding the fluxes of energy between these two systems is currently available. Until this information becomes available, it will be difficult to determine to what extend the ecological integrity of fresh coastal wetlands is under the dependence of such physical external pulsing event. Through field sampling and lab analysis, our project investigate the potential for outwelling of organic matter from a Great Lakes

This holistic proposed research is significant because it will shed light on the ecological link between two-coupled systems (e.g., lake and coastal wetland) placed under the influence of a physical pulsing event (e.g., seiche). This study will provide fundamental results by which the outwelling concept (e.g., export of organic matter) can be tested in fresh systems. Because many coastal wetlands (particularly in Lake Erie) are today artificially isolated from the lake and no longer under the influence of daily water level fluctuations, the contribution of these coastal wetlands to Lake Erie's food web – by exportation of the organic matter produced in-situ – is likely limited. If it is demonstrated that the export of organic matter between a wetland and the lake is substantial, and serves an overall beneficial role to the lake food web, entirely new wetland management practices may be needed.

The objectives of the proposal will be achieved by a combination of field sampling and lab analysis of carbon species (dissolved, coarse and particulate) concentrations in water and stable isotope signature of various compartments of aquatic ecosystems. Natural stable isotope (¹²C and ¹³C ; ¹⁴N and ¹⁵N ; ³⁴S and ³²S) abundance will be measured to determine the source and pathways of organic matter in the wetland-Lake coupled systems. Macrophyte, algae, zooplankton and larval fish will be sampled four times a year, along longitudinal gradients. Water samples will be taken at the outlet of the wetland, during both flow directions of seiche events. Other water samples will also be taken in the wetland and the lake along the same gradient. A combination of carbon and stable isotope analysis will allow us to determine the pathway of carbon fluxes in the wetland, in the lake, and between these two systems.

We have investigated the fluxes of dissolved organic carbon (DOC), particulate organic carbon (POC) and coarse particulate organic carbon (CPOC) between a coastal wetland and Lake Erie during seiche events. Once a week, we sample an entire seiche (duration varied between 12 and 24 hours, depending on weather conditions) every hour. Such protocol gives an average of 14 samples per seiche (i.e., 7 with the flow getting into the marsh and 7 with a flow going out of the marsh). CPOC is collected at the opening of the marsh with two-paired 303-µm-mesh push nets operated simultaneously. Attached flow meters are used to determine the volume of water sampled, and will allowed us to calculate the budget of detrital material entering and leaving the wetland. At the same time, a 2-L sample bottle is used to collected water sample for POC and DOC analysis. In the lab, detrital material is washed with deionized water, dried at 105°C and weighed to estimate a dry weight (DW) of biomass. Half of