I'm putting together a setting for a series of stories (possibly a novel as well, though who knows) involving a single large city on a planet newly colonized by humans who left Earth. The idea is that this planet has only a little bit of liveable land - most of it's covered by oceans, let's say - so necessity forces the colonists together. Moreover, the colonists left Earth in ships that were largely homogeneous in terms of nationality, language, and culture and spent several decades on those ships before landing on the new planet.
Do you think these different groups would be able to effectively operate as a single political entity after landing on the new planet? Do you think they'd want to do so? I'm envisioning a sort of city-state with an elected republican form of government that includes citizens of many different cultural and linguistic backgrounds, but in a city that's still somewhat divided down cultural and linguistic lines (for example, there might be a largely Chinese district, an Arab district, etc.) I'm just not sure how realistic that vision is. I can see this kind of experiment easily falling into revolt and chaos, especially if resources are scarce or if one or several national/ethnic groups end up politically and economically dominating others.