Assessing potential limitations when characterising the epibiota of marine megafauna: Effect of gender, sampling location, and inter-annual variation on the epibiont communities of olive ridley sea turtles

- Epibiont communities of nesting and free-swimming olive ridley sea turtles were characterised.
- The majority of mobile epibionts appear to remain on sea turtle hosts even if they leave the water.
- Epibiont communities of nesting turtles were not different to those sampled at sea.
- Epibiont communities of olive ridley turtles differ between sexes.
- Further studies are required to understand the factors driving individual variation in epibiont communities.

The epibionts of marine megafauna can serve as valuable indicators of the host's health or behaviour; however, only a few studies have attempted to determine how and why epibiont communities vary between host individuals, populations, or even species. Further complicating efforts to compare epibiont communities of marine megafaunas is that measures of epibiont abundance and diversity may be influenced by the sampling methods and timing of the assessment. Here, we examined how host gender, geographic location, and sampling year affect measures of epibiont community structure in olive ridley sea turtles, Lepidochelys olivacea, in the East Pacific Ocean. To achieve this, we identified, enumerated, and then statistically compared the epibiont communities of (1) nesting female turtles sampled over different nesting seasons, (2) female turtles sampled on nesting beaches and at sea, and (3) female and male turtles, both sampled at sea. We did not discover statistically significant differences between the epibiont communities of nesting female turtles sampled on different years nor between females sampled on nesting beaches and at sea. However, we did observe a statistically significant difference between the epibiont communities of female and male turtles. Thus, we conclude that while sampling epibionts from nesting sea turtles may be an accurately and more logistically straight-forward method than sampling turtle at sea, it should not be assumed that epibiont communities of male and female hosts are identical. We also suggest that knowledge of the factors that drive intra-specific variation in the epibiont communities of marine megafauna, be it biological or methodological factors, is necessary before broader-scale meta-analyses are made to determine spatial and temporal patterns in the distribution of epibiont communities worldwide.