Moray eels may not be directly eating kelp but a special chemical tracing technique reveals moray eels eat the creatures that eat kelp. Research on moray eel diet at Santa Catalina Island by UC Santa Cruz & SDSU suggests morays eat mostly fish like kelp bass and molluscs like octopus. A chemical tracing technique called stable isotope analysis is used to determine what important food sources are and follow these sources of energy up food webs to predators. We are able to take advantage of chemical signatures in producers that can be traced to consumers. This technique allows us to determine which energy sources are most important. Kelp is seen in morays as it is consumed by invertebrates that kelp bass eat, and morays consume the kelp bass. It would be interesting to see how the loss of kelp around Santa Catalina effects the abundance of creatures that morays eat and how they then alter their diet.
Capturing the moray eels is the hard part. Catch and release has been used to capture the eels and learn about moray eel populations off Santa Catalina Island. Modified fish traps have been used by researchers (Rita Mehta and Ben Higgins at UC Santa Cruz) to estimate the densities of morays. After being caught, the morays are hauled up into the boat, given a mild sedative, and measurements like length, weight, and the distance they can open their mouth is taken. These measurements will be used to get an idea of the range of these measurements in the population. Morays may have a large effect on the kelp forest community at locations where morays can be very abundant like Santa Catalina Island in southern California. Future work and collaboration with UC Santa Cruz will seek to determine how morays change their diet as they grow older and how big of an effect these morays have on the kelp forest community.
Below is a short video of kelp at Santa Catalina Island. Giant kelp provides structure and food for many organisms creating a diverse kelp forest community.