A group of settlers from a mid-renaissance era have setup an initial settlement along a coastline. Materials for shelter exist and fishing serves as the initial food source. What are the primary concerns from the environment that have to be addressed for the colony to remain stable?
The first concern is always going to be fresh water. Next to the coast there is a ton of salt water but without fresh the colony won't last long. A nearby river that feeds into the coast or wells quickly need to be discovered.
Harbor: fishing may provide a food source, but if you don't have a good harbor, natural or manmade, your fishing boats will be destroyed in a storm. You will also needs some basic docks to do repairs on your boats.
Defense: almost all colonies have to set up defense. Since this is a new colony it is likely far from support and in potentially hostile lands. Scouts will need to be sent out and a pallisade of some sort will need to be constructed.
Surroundings: Depending on the weather, the settlers will need to adjust to hot summers/freezing winters/hurricanes/droughts/frequent storms. This will determine the shelters they build, their lifestyle, and the clothing. Depending on severity, this events could be settlement ending or just a strong struggle to adjust. Additionally, there could be dangerous predators/new diseases/different plants that are poisonous, medical, addictive, or good for food that the colony needs to discover and deal with.
Trade/raw resources/farming. Eventually people will get tired of fish. Hunting animals, farms or other sources of food will need to be used. People will need other goods as well, such as clothing or metal. The colony either needs to set up trade with the homeland or begin to manufacture goods themselves. To do that they need something to trade. Maybe just fish but it will likely expand to find new resources to support itself or trade.
Government: any colony must have a means of government. This ins't strictly environmental and should have been determined before the colony was founded but it is important to the long term health of the colony. This would also determine how more people were allowed into the settlement. Do they aggressively recruit more people? Do they have certain standards or conditions on new arrivals? Are they a religious or political settlement with a specific purpose? Are they a prison settlement? How to accept/encourage new immigrants needs to be decided to allow the colony to grow.
Wouldn't the climate have an impact on this?
For example, taking Earth as a model, if these settlers found themselves in the temperate regions (think New England coast), they would need to concern themselves with harsher winters with lower temperatures and the possibility for reduce fishing harvest due to colder water or more frequent storms at sea.
Additionally, with harsher winters, there would be more need for robust shelters to protect themselves from the elements, as well as provisions for storing food to last through the winter months.
However, if they were in a more sub-topical environment (think Florida or Mediterranean coast), they would have more temperate climate, requiring less robust shelters (tents probably would be sufficient) and have a more regular access to fish and other food sources. Although, depending on their location they may have to deal with more intense storms moving through the area periodically. I'm thinking here of Hurricanes and other tropical storms.