Abstract
Fresh waters are particularly vulnerable to climate change, which affects temperature as well as other physical and chemical water properties. Temperate Northern lakes have shown an increasing temperature trend in the last decades, and climate models proj ect a continued temperature increase of surface waters as well as changes in stratification patterns. In this project we take an innovative approach to study ecosystem responses to climate change, by extending the demographic framework of integral project ion modeling (IPM) to include key drivers of climate change, and applying it to unique long-term individual-based data from two freshwater fish species, brown trout (Norway) and pike (UK). As top predators, the responses of these species to climate change may have large consequences for the ecosystems. IPM is a powerful approach that can incorporate population structure from a mixture of discrete and continuous state variables, such as age and body size. Size structure is rarely considered in relation to climate change, but it is most likely important because many organisms have highly size-dependent vital rates. Here, we will study consequences of climate change in combination with harvesting, eutrophication, and stocking, as well as threshold effects of extreme events. Based on developed climate change scenarios for the two local regions we will use our models to project future responses to climate change. We will also consider opportunities for adaptive management based on the new approach. This projec t brings together recently developed theory and existing data in a synergistic fashion that will help answer some of the unresolved questions of climate change research. Analyzing these questions in the context of size-structured populations is at the fro ntier of ecological research, and acknowledges the need for management to be size-specific. Our results will provide valuable knowledge for management of size-structured organisms, also beyond aquatic ecosystems.
Norway