The response of aquatic communities to disturbances in Mediterranean shallow lakes
Ministerio de Economía, Industria y Competitividad
Programa Estatal de I+D+i Orientada a los Retos de la Sociedad
Ref. CGL2016-76024-R (AEI / FEDER /UE)
Disturbances in shallow lakes in the Mediterranean area, such as flooding events, are usually pulse-type, after which productivity (production / biomass) and resource availability tend to diminish. Other non-hydric disturbances in the Mediterranean region, such as wildfires, are also pulse type. Aquatic communities should be adapted to a decrease in nutrient availability with time as well as to an increase in organisms’ concentration coinciding with the decrease in water level. Anthropogenic activities usually cause more gradual or permanent press-type changes in these shallow lakes, such as changes in the hydrological regime or eutrophication by nutrient inputs. Since these disturbances are mainly of human origin, we start from the assumption that aquatic communities of these shallow lakes are resilient to pulse disturbances and adapted to the diminution of resource availability that occurs after them. Resilience also appears at metacommunity scale, since under natural conditions, communities that colonize these aquatic environments are distributed in networks of more or less connected water bodies. On the other hand, these communities would be more sensitive to gradual nutrient inputs, usually of anthropogenic origin, that provide nutrients over a long period of time and increases productivity and resource availability. Gradual changes would have a setback on the successional pattern and would cause that community structure do not follow the characteristic pattern, favouring species with more opportunistic strategies.
In this project we compare the response of aquatic communities to pulse type disturbances and to gradual nutrient inputs with the aim to determine if there are regularities between community structure and productivity and resource availability. We also analyse these responses at a metacommunity scale, comparing systems with lesser or greater degree of connectivity. We develop this studies in two types of Mediterranean lentic ecosystems: coastal lagoons (objectives 1 and 2) and temporary ponds (objective 3). Both are included in the Habitats Directive of the European Commission (Council Directive 92/43/EEC, Annex 1) as priority natural habitat types of community interest.
HYPOTHESES AND OBJECTIVES
General objective: To determine the response of the aquatic community to pulse type (such as flooding events or wild fires) and press type (such as gradual changes in nutrient availability) disturbances.
Working hypothesis: that aquatic communities of Mediterranean lenitic environments is highly resilient to intense pulsatile disturbances, as long as the metacommunity structure is maintained with some degree of connectivity between waterbodies, and is adapted to the trend of decreasing resource availability that occurs after such a disturbance. These aquatic communities are, on the other hand, very sensitive to the gradual inputs of nutrients, generally of anthropic origin, which maintain high productivity and availability of resources over time.
1. To determine the metabolism of Mediterranean shallow lakes and to verify the relationship between disturbances, productivity and community structure (Hydrology and ecosystem metabolism)
2. To compare the response of the aquatic community in natural and/or man made habitats to pulse or gradual disturbances (Response to disturbances)
3. To model the response of aquatic communities to high intensity pulse disturbances at a metacommunity scale (A metacommunity approach)