Roberts, Emily; Newcomb, Laura; McCartha, Michelle; Harrington, Katie; LaFramboise, Sam; Carrington, Emily; Sebens, Kenneth

Many plants and sessile animals invest in mechanical attachment to their habitat by producing structural materials. The cost of this attachment can depend on the amount of structure produced to stay attached, but little is known about how much energy many organisms invest in such structures. One way that scientists evaluate how much energy animals invest in different behaviors and physiological processes is with an energetics framework. Marine mussels are a group of species found on rocky shores and farmed globally, and produce a network of ‘byssal’ threads to stay attached to their natural and farmed habitats.
In this study, we severed mussel byssal threads across a range of frequencies (daily, weekly, and never) during a month-long experiment. Severing the byssus more frequently (e.g. daily) caused mussels to produce more threads.
We found that mussels that make more byssal threads grow less. We then combined this trade-off between byssal thread production and growth with an energetics model (Scope for Growth) to evaluate the cost of producing this structural material.