Some ecotourism offers visitors close encounters with different species. But new research suggests that these activities may not be so great for the animals. Researchers tagged stingrays in Stingray City in the Cayman Islands to monitor their movements and behavior. Compared to stingrays outside of the tourism area, those in Stingray City switched their activity patterns from night to day, when tourists handed out food, and mated year round instead of seasonally. The stingrays also had more bite marks , which suggests increased aggression towards one another. The study is in the journal PLoS ONE. Past research has found increased stress and more intra- and inter- species aggression among animals that have been fed by humans. Interactive tourism is a growing business. But researchers say that more study is needed to ensure the health and safety of humans and animals alike. Ecotourism may be good for a given species, as humans become engaged in its survival . But for the individual members of that species tasked with dealing with people, it may not be a walk in the park.