Conclusions
While it has been well documented that only select species engage in cleaning behaviors, any additional functional redundancy of gnathiid consumption provided by the many fish species that consume invertebrates either primarily or nominally was unknown. Here we show that although many species consume gnathiids, the totality of their consumption is insignificant compared to both dedicated and facultative cleaners. Additionally, while dedicated and facultative cleaners consumed similar amounts of gnathiids, the differences in client diversity suggests that facultative cleaners occupy a complementary cleaner role to that of dedicated cleaners. Thus, we feel that both cleaner functional groups are high priority for conservation and that, in fact, they cannot be replaced. However, the preservation of complete cleaning services for all species requiring it will be dependent on the conservation of reef-building Scleractinian corals that serve as the base for goby cleaning stations. The results presented here show that cleaning may be a more significant component of the ecology of T. bifasciatumthan previously thought. Indeed, they may have the capability to suppress gnathiid populations on the Caribbean coral reefs. However, the factors determining how often T. bifasciatum engages in cleaning, as well as the degree to which intraspecific differences in cleaning behavior exist, will be important to determine going forward. Cleaning services are unique and critical for the maintenance of coral reef health. Although we find both facultative and dedicated cleaners to be important, dedicated cleaners occupy a niche that is in jeopardy and seems to be irreplaceable by any other fish functional group.