Researcher disciplines and the assessment techniques used to evaluate Laurentian Great Lakes coastal ecosystems

The Laurentian Great Lakes of North America have been a focus of environmental and ecosystem research since the Great Lakes Water Quality Agreement in 1972. This study provides a review of scientific literature directed at the assessment of Laurentian Great Lakes coastal ecosystems. Our aim was to understand the methods employed to quantify disturbance and ecosystem quality within Laurentian Great Lakes coastal ecosystems within the last 20 years. We focused specifically on evidence of multidisciplinary articles, in authorship or types of assessment parameters used. We sought to uncover: 1) where Laurentian Great Lakes coastal ecosystems are investigated, 2) how patterns in the disciplines of researchers have shifted over time, 3) how measured parameters differed among disciplines, and 4) which parameters were used most often. Results indicate research was conducted almost evenly across the five Laurentian Great Lakes and that publication of coastal ecosystems studies increased dramatically ten years after the first State of the Great Lakes Ecosystem Conference in 1994. Research authored by environmental scientists and by multiple disciplines (multidisciplinary) have become more prevalent since 2003. This study supports the likelihood that communication and knowledge-sharing is happening between disciplines on some level. Multidisciplinary or environmental science articles were the most inclusive of parameters from different disciplines, but every discipline seemed to include chemical parameters less often than biota, physical, and spatial parameters. There is a need for an increased understanding of minor nutrient, toxin, and heavy metal impacts and use of spatial metrics in Laurentian Great Lakes coastal ecosystems.     

What do our lakes mean to us? An understanding of Michigan coastline communities’ perceptions of the Great Lakes

Four of the Great Lakes and Lake St. Clair serve as part of the 5261 km coastline of the State of Michigan. Understanding of the relationship between Michigan residents and these Lakes are important for the creation of messages designed to instill the desire to become better stewards of the Michigan coastline. Focus groups totaling 100 Michigan residents were held across the State to learn how residents feel about general issues facing Michigan’s coastline. The two major themes that emerged from the focus groups were issues related to the rising lake waters and the need for education on coastline awareness and stewardship. Other important themes emerged for the focus areas of the research team and its funding organization. There were differences of opinion on some of the issues between residents of the Upper and Lower Peninsulas (for example, public access was not as important an issue in the Upper Peninsula) and also for residents of Lake Michigan versus Lake Huron coastlines in the Lower Peninsula (storms are causing more damage and erosion on the Lake Michigan beaches).     

Quantifying the influence of cold water intrusions in a shallow,coastal system across contrasting years: Green Bay,Lake Michigan

We present water column thermal structure for two climatically different years: 2012, which experienced abnormally warm spring and summer air temperatures preceded by a relatively low ice winter and 2013, which experienced cooler than average spring and average summer air temperatures and preceded by average ice conditions. Mean bottom water temperatures for the season and during cold water intrusions were significantly warmer in 2012 than 2013 leading to a significantly reduced stratified season in 2012. Cold water intrusions were driven into southern Green Bay by southerly winds while intrusions were terminated when winds switched to persistent northerly winds. 2012 observed a significant increase in northerly winds relative to 2013, decreasing cold water intrusion presence and duration but winds did not fully explain the difference in thermal conditions for southern Green Bay. These cold bottom waters drive stratification in polymictic southern Green Bay while dimictic waters were found to have significantly warmer bottom temperatures during 2012 and a deeper mixed layer. Our observations suggest that relatively shallow (<20?m), seasonally stratified systems may not increase in stratification strength and duration under a warming climate; rather, changing wind climatology and surface heat flux can inform the degree to which the mixing regime can be expected to change and impact stratification and thermal structure of coastal systems. We discuss the biogeochemical implications of different thermal regimes, particularly within the context of multiple drivers of physical water column structure in eutrophic, stratified coastal systems.     

Enhancing Great Lakes coastal ecosystems research by initiating engagement between scientists and decision-makers

A disconnect between scientific research and environmental management communities can be a detriment to both. In the case of Great Lakes coastal ecosystems, which are inherently complex and subject to uncertain effects of future climatic, environmental, and anthropogenic drivers, greater collaboration could be beneficial to their sustainability. We capture the challenges and opportunities identified by a scientist/decision-maker co-production workshop focused on the future environmental quality of Great Lakes coastal wetlands. We explain our path through the stakeholder workshop process, our challenges in translating meeting outcomes into actionable items, and lessons learned to bridge gaps between scientists and decision-makers. Additionally, we determine topics and directions identified by decision-makers that can be modeled with existing technologies and others that require further research. These topics may be incorporated into future research efforts and could serve as a shortlist of research priorities that were identified by decision-makers working with coastal wetland issues. Based on lessons learned during and after the workshop, we provide suggestions for bridging the gap between researchers and decision-makers, including sustained engagement between these groups and improved interaction through the beginning, duration, and end of research and/or management efforts.     

Invasive cattail reduces fish diversity and abundance in the emergent marsh of a Great Lakes coastal wetland

Great Lakes coastal wetlands (GLCWs) provide critical fish habitat. The invasion of GLCWs by hybrid and narrow-leaved cattail, Typha × glauca and Typha angustifolia (hereafter Typha), homogenizes wetlands by out-competing native plant species and producing copious litter. However, the effect of this invasion on fish communities is little known. To measure the effect of Typha on fishes, we established plots in Typha invaded and native wetland emergent zones in a northern Lake Michigan coastal wetland, and measured environmental variables, plants, and fishes in each zone over two summers. Dissolved oxygen and water temperature were significantly lower in invaded compared to native plots. Invaded plots were dominated by Typha and its litter; whereas. sedges (Carex spp.) were the most abundant species in native plots. Fish abundance and species richness were significantly lower in Typha compared to native wetland plots. The Typha fish community was dominated by hypoxia tolerant mudminnow whereas other small, schooling, fusiform species such as cyprinids and fundulids were absent. These results illustrate the negative impact of a dominant invasive plant on Great Lakes fishes that is expected to be found in Typha invasions in other GLCWs.     

Characterizing the cultural ecosystem services of coastal sand dunes

Coastal sand dunes provide an array of important benefits that are supported by coastal geomorphic processes and location-specific ecosystems, including direct and indirect economic benefits to humans. Coastal sand dune ecosystems are ecologically important, but their specific values and uses are little studied, poorly understood, and underappreciated. Michigan, USA, is home to the largest land area of freshwater coastal sand dunes in the world. This study used an online survey that allowed participants to record the types of activities in which they engaged during visits and respond to questions about the importance of the cultural ecosystem services of coastal sand dunes. The survey captured the responses of 3610 individuals, a majority of whom rated scenic beauty, protection for future generations, protection of a unique ecosystem, and outdoor recreation as extremely important or very important. The survey results provide some preliminary insights into the role of cultural ecosystem services of coastal sand dunes in providing and sustaining benefits for humans and how these benefits and values are perceived by the public. These insights have important implications for policy makers responsible for coastal zone management in the Great Lakes region and in other areas characterized by coastal sand dunes ecosystems.     

Watershed and lake influences on the energetic base of coastal wetland food webs across the Great Lakes Basin

We examined factors that influence the energy base of Great Lakes coastal wetland food webs across a basin-wide gradient of landscape disturbance. Wetland nutrient concentrations were positively correlated with a principal components-based metric of agricultural practices. Hydraulic residence time influenced the energy base of wetland food webs, with high residence-time systems based mostly on plankton and low residence-time systems based mostly upon benthos. In systems with plankton, the importance of planktonic carbon to the resident fish community generally increased with residence time. A stronger relationship was apparent with an index of nutrient loading that combined residence time and nutrient concentration as the predictor (R² = 0.289, p = 0.026). Shifts toward plankton-based food webs occurred at relatively low levels of loading. In riverine wetlands without plankton, contributions of detrital carbon to fish communities decreased significantly in response to watershed disturbance that reflected nutrient loading. In a third class of wetlands the wetland-resident fish communities were not entirely supported by within-wetland carbon sources and were significantly subsidized by nearshore habitats, which provided 35 (± 22) to 73 (± 9) % of fish community carbon. When lake-run migrant fish were included in the analyses, nearshore subsidies to all 30 wetland food webs ranged from 3 (± 2) to 79 (± 12) %. We obtained similar ranges when examining nearshore contributions to a single wetland species, northern pike. These results illustrate the spatial scale and the degree to which the energetics of coastal wetland food webs are influenced by interactions with their watersheds and Great Lakes.