Improving Understanding of Drought Impacts in Coastal Ecosystems

Current systems of drought monitoring and management focus primarily on agricultural impacts and maintaining water supplies for municipal and industrial use, energy production, and navigation. Although many efforts to improve capacity to monitor, forecast, visualize and communicate drought conditions (e.g. US Drought Monitor, state and local planning efforts, technical work to develop and improve drought indicators and indices) are underway, understanding of drought impacts to many other sectors remains limited. Furthermore, such impacts (e.g. environmental, water quality, health-related, secondary and lingering effects) are currently not well-integrated into existing decision making, planning, and response processes at national, regional, state, and local levels. Information about impacts can help improve understanding of drought vulnerabilities, which can be used for developing and targeting mitigation and adaptation strategies. However, without a well-developed understanding of impacts, it is likely that state and community response plans do not fully address impacts to other sectors and resources.

The impacts of drought on coastal ecosystems is one of the major gaps in overall understanding of drought impacts. Investigations of the full range of drought and low flow vulnerabilities are needed to inform management and drought early warning systems. This paper reports on a study to expand understanding of the impacts of drought on coastal ecosystems in the Carolinas, an area where these impacts are poorly understood. This study included a review of drought-related ecological research, workshops with coastal resource managers from North and South Carolina, and 20 semi-structured interviews with local stakeholders in Beaufort County, SC. This project serves as a first step in understanding the information and/or actions that are necessary to better integrate coastal-environmental needs into drought monitoring, planning, and response by identifying gaps in existing knowledge and primary stakeholder concerns.

The ecological literature does not discuss drought in terms used in drought research, monitoring, or management (agricultural, meteorological, hydrological [i.e. for water supply]). Rather, drought is discussed primarily in terms of the hydrology-related impacts that affect coastal ecosystems (river discharge, water level, water table depth) and subsequent ecological effects. The biggest stressors associated with drought in coastal ecosystems are reduced freshwater inflows and changing salinity and nutrient concentrations. Such changes may affect water quality, kill vegetation along increasingly brackish channels, reduce populations of estuarine organisms, and affect shrimp and shellfish communities. This review highlights a key gap in existing drought indicators and monitoring efforts: they do not include salinity measures, a significant factor in coastal ecosystems' sensitivity to drought events. Workshops with coastal resource managers highlighted the need for tools or indicators that would help to assess ecological changes that may be caused by drought.

Interviews were used to improve understanding of drought sensitivities in coastal ecosystems by documenting and assessing local impacts and experiences. Interviewees included fishermen (commercial, recreational, subsistence), refuge managers, and recreational businesses that use and depend on coastal environmental resources and thereby may be affected by drought. Drought has impacted commercial fishermen most directly by affecting shrimp and shellfish conditions. Businesses have been adversely affected financially by reduced catches. Coping and adaptation strategies include diversifying fishing activities and changing business practices. Many interviewees reported observing longer-term changes in the local environment (e.g. vegetation change, species abundance) and concerns about the cumulative effects of drought in relation to other system stressors (e.g. land use change, development, and wetland loss).