Laguna is a city located on the south-central coast of Santa Catarina, founded in 1676, and where important historical events took place, such as the Farroupilha Revolution and the well-known transatlantic romance, between the revolutionaries Anita and Giuseppe Garibaldi, heroes in Brazil and Italy. In addition to its historical relevance, the region was graced by unique natural beauties, such as the Estuarine System of Laguna, which is composed of three units: Lagoas de Santo Antônio, Imaruí and Mirim. These lagoons harbor a high biodiversity of animals and plants and provide food resources (fish, crabs) as well as places for recreation to the countless residents of the region.
An unpretentious walk around the lagoons of the Estuarine System to watch fishermen, porpoises and cormorants (as well as other species) moving around to search for food (and entertainment) is a unique spectacle. How can so many “people” get fed up and the fish not run out? Do all these animals eat the same thing? If one species eats a lot and the other a little, what happens? These are all simple and frequently asked questions, by curious viewers of all ages who spend time in the Laguna region. The simplicity of these questions embodies a fine ecological perception that the components of biodiversity we see (and those we don’t!) are intimately connected to each other through complex interactions.
In fact, ecological interactions occur at all scales of nature and form an invisible tangle to human eyes, called the trophic network. This concept is very important in ecology, as it allows us to understand how species relate to each other through interactions such as predation and competition for resources, also showing how energy flows in an ecosystem. In this way, the construction of an ecological model of trophic networks makes it possible to understand the structure of an ecosystem (such as the lagoons of the Estuarine System), making it possible to predict how environmental changes and variations in the abundance of certain species directly and indirectly reflect on other species, and also on fishermen and local residents. In a world scenario of high rates of species loss, ecological models that can predict the future become essential tools to discuss the management and conservation of natural resources.
In this sense, building a trophic network model for the Laguna Estuarine System is one of the main goals of the Long Term Ecological Research Program (LTER) “Systemic effects of a rare cooperation between porpoise and fisherman”. This program is funded by CNPq (National Research Council). Our goal is quite a challenge! After all, to build such a complex ecological model, information about various components of the ecosystem is needed. For example, we will need to estimate the input rate of debris from the mangrove and marsh plants into the Estuarine System, as well as estimate the biomass of microscopic algae, microcrustaceans, zooplankton, shrimp, crabs, fish (of various species), birds and porpoises that live in the study area. We will also need to know which items and how much of these items these species eat, which will allow us to determine the direct and indirect relationships between local species. Another vital piece of information for the model will be to determine the annual capture of the different types of fishing that occur in the ecosystems of the region.
There is a lot of information that will be obtained through sampling campaigns in the field and laboratory activities. With these information, the work will be to summarize the data and adjust the trophic network model with maximum parsimony, in order to generate robust information that makes it possible to understand the studied ecological system and also support the management of anthropic activities in the region. It takes a lot of work, but as scientists, we love it all…
Undergraduate, master and PhD students will be involved in the mentioned stages, as well as professors from UFSC, UDESC and other national (UFSCAR, UFRJ, UFRGS and UFRN) and international (University of Oregon, USA) educational institutions. The researchers are pretty excited and curious, as children, to know how species, including humans, interact in the historic lagoons of the Laguna region.