Background and Rationale
Aquaculture of shellfish provides numerous jobs, generates a large revenue, and aids in economic stability in Prince Edward Island (PEI); however, a long history of over-fishing, climate change, and rising pollution levels have significantly impacted their populations (PEI Department of Agriculture, Fisheries and Aquaculture [DAFA], 2005; American Physiological Society, 2006; LeBlanc et al., 2007). Mussels provide essential ecosystem services and act as a keystone species that promotes a stable and healthy ocean ecosystem (Connecticut Department of Agriculture, 2022). Mussels grow by fusing together on a clean substrate creating beds that provide habitat, predator protection, increases species diversity, and reduces erosion from storms and floods (Office of Habitat Conservation, 2022; Paetzold et al., 2012). Additionally, mussels filter water through their feeding process which reduces nutrient overload, prevents the spread of toxins through bioaccumulation, and promotes the growth of many aquatic organisms (Office of Habitat Conservation, 2022; Carman et al., 2016). Due to the countless benefits of mussels, it is essential to understand what impacts them in order to promote healthy populations that can boost the economy and ocean ecosystems (PEI Department of Agriculture, Fisheries and Aquaculture [PEI DAFA], 2005).
Unfortunately, there is a general decline in their populations over recent years (Office of Habitat Conservation, 2022; LeBlanc et al., 2007). Numerous studies have found that tunicate densities increase with rising ocean temperatures, and with recent climate change models, we can expect that a rise in tunicate levels as well as a shift northward will occur (Lubofsky, 2022). Tunicates negatively impact mussels by directly competing for food and causing suffocation by growing over them (Daigle and Harbinger, 2009). This causes smaller sized mussels, higher mortality rates, and the inability to function and reproduce successfully (Daigle and Harbinger, 2009). Fortunately, there are various management options to control tunicate levels based on the tunicate densities, and type, as well as seasonality (Carman et al., 2016).
Mussels are also impacted by temperature. Many studies have found that rising temperatures increases the energy needed for mussels to function which places stress on the organism (American Physiological Society, 2006; Daigle and Harbinger, 2009). Other researchers have concluded that above a certain temperature threshold mussel mortality increases (La Peyre et al., 2016). However, studies often suggest that the effect of temperature on mussels is population dependent, therefore, by determining the localized relationship between temperature and these shellfish organisms we can determine how temperature is expected to influence their production over the next couple years and how to manage it within PEI (Lowe et al., 2017).
Unfortunately, there is a general decline in their populations over recent years (Office of Habitat Conservation, 2022; LeBlanc et al., 2007). Numerous studies have found that tunicate densities increase with rising ocean temperatures, and with recent climate change models, we can expect that a rise in tunicate levels as well as a shift northward will occur (Lubofsky, 2022). Tunicates negatively impact mussels by directly competing for food and causing suffocation by growing over them (Daigle and Harbinger, 2009). This causes smaller sized mussels, higher mortality rates, and the inability to function and reproduce successfully (Daigle and Harbinger, 2009). Fortunately, there are various management options to control tunicate levels based on the tunicate densities, and type, as well as seasonality (Carman et al., 2016).
Mussels are also impacted by temperature. Many studies have found that rising temperatures increases the energy needed for mussels to function which places stress on the organism (American Physiological Society, 2006; Daigle and Harbinger, 2009). Other researchers have concluded that above a certain temperature threshold mussel mortality increases (La Peyre et al., 2016). However, studies often suggest that the effect of temperature on mussels is population dependent, therefore, by determining the localized relationship between temperature and these shellfish organisms we can determine how temperature is expected to influence their production over the next couple years and how to manage it within PEI (Lowe et al., 2017).
Research Objectives
The Oyster Monitoring Program (OMP) was developed to inform fishermen on the specific details of local mussel production (Department of Fisheries and Communities, 2022), however, the data collected can be analyzed to determine if there are any significant relationships between environmental conditions, other organisms, and mussels. To investigate the stability of mussel populations in PEI, we can quantifying the effects of water temperature and tunicate density on mussel productivity from 2002-2018. Based on our literature review we expect rising ocean temperatures to cause higher mussel larvae size to a certain threshold beyond which productivity will decrease. Additionally, we expect tunicate densities to negatively impact mussel production. However, if these expectations do not occur, then the current management of mussels within PEI may not need to be adapted.
Picture citation: (Binns, 2020)
Disclaimer: When the term "mussels" is used throughout this website, it is referring to both mussels and oysters. This is due to the fact that the OMP collected oyster and mussel data but failed to differentiate between them when recording data.