Rising seas could give non-native marine animals new coastal habitat
A model published September 28 finds that much of the land expected to flood as seas rise could become suitable habitat for established non-native marine animals. The researchers compared projected inundation with environmental conditions and the ranges of 122 species; an independent report described the same study. Estuaries at middle latitudes stand out. This is a map of potential habitat, not evidence that those animals have reached, colonized or harmed every projected coastline.
Science··Midday
The moving coast creates new space
Sea-level rise changes more than the shoreline on a map: some land that is dry today could become shallow coastal water. A Nature Ecology & Evolution study published September 28 examines whether such newly flooded ground could suit marine animals already established outside their native ranges. AFP and The Paper separately reported the same central finding. The researchers considered 122 non-native species and projected inundation for the middle and end of this century. Their result is that a large share of flooded land could have environmental conditions compatible with at least some of those animals. It is a potential route for their spread inland as the coast moves, not evidence that the species have already crossed that future boundary.[1], [2], [3]
The model maps suitability
The team combined known distributions of the selected animals with projected flooding and environmental conditions. It estimates roughly 290,000 to 470,000 square kilometers of future inundated coastal land as suitable under its scenarios, amounting to more than two thirds of the flooded area it examined. Estuaries at middle latitudes feature prominently. An estuary is the coastal meeting place of river and sea water, so changes in the land-water boundary there can create new shallow habitat. These figures come from a model, and the range varies with the time horizon and climate assumptions. AFP’s account also identifies the 122-species comparison and the concentration around estuaries; detailed modelling choices rest with the direct paper.[1], [2]
Suitable does not mean occupied
Environmental suitability is only one step in a biological invasion. An animal must reach a place, survive, reproduce and interact with the local community before a new population or harm can be observed. The paper does not track future individuals, and its map cannot say which particular flooded neighborhood will host a given species. Coastal barriers and connections could also change what happens locally. The Paper’s report treats the study as a possible expansion pathway, and AFP describes potential effects rather than completed spread. The useful change in perspective is that future marine monitoring may have to look toward land that is not yet underwater, alongside existing coasts. The study establishes a scenario to examine, not a certain ecological outcome.[1], [2], [3]
