Inter-annual variations of macrobenthic communities over three decades in a land-locked coastal lagoon (Santo André, SW Portugal)

Abstract

Keywords: macrobenthic communities land-locked coastal lagoon ecological status long-term changes water framework directive a b s t r a c t Santo André is an enclosed brackish water coastal lagoon with temporary connections to the sea by a man-made channel. The exchange and mixture of saltwater and freshwater is irregular and the lagoon may show daily and seasonal fluctuations, but also long-term variation. Different benthic communities may be present along the annual cycle according to the magnitude of episodic freshwater and sea water inputs.In the last 30 years the communication with the sea has followed different regimes from year to year and, as a consequence, macrobenthic communities, assessed several times during the period before the opening to the sea, shifted from freshwater to marine affinities. Major differences were found between 1979 and 2010, with a preponderance of species with marine affinity, and the 1980s in which the organisms with freshwater affinity prevailed. Benthic communities are frequently used to assess aquatic environmental condition. Metrics used in the indices currently under discussion to assess ecological status of aquatic ecosystems within the scope of European Water Framework Directive were applied to Santo André data and the applicability of these metrics to assess quality in this coastal land-locked lagoon was discussed.

Effects of organic pollution and physical stress on benthic macroinvertebrate communities from two intermittently closed and open coastal lagoons (ICOLLs)

“…The benthic macrofauna density in both lagoons was higher than in Albufeira coastal lagoon (Quintino and Gentil, 1988) and approximately 50% higher than the ones observed in Santo André, where mean annual densities were always lower than 10x10 3 ind.m -2 (Correia et al, 2012).…”

Impact of freshwater inputs on the spatial structure of benthic macroinvertebrate communities in two landlocked coastal lagoons

“…The present results showed that, like in open brackish systems, such as estuaries (Silva et al, 2012), the structure of benthic communities is strongly associated and dependent of freshwater inputs. Thus, and although additional information is required to quantify this relationship, it is reasonable to consider that unsustainable groundwater abstraction can have a strong impact on the biological communities of enclosed lagoons.…”

“…Santo André lagoon, on the other hand, appears to buffer freshwater input and displays a certain degree of zonation (e.g. Elliott & Whitfield, 2011;Correia et al, 2012;Félix et al, 2013a, b).…”

“…that have short period or no connection to the adjoining sea, termed as landlocked or enclosed lagoons (Bamber et al, 2001;Beer & Joyce, 2013). This knowledge gap is particularly significant with regard to the factors that modulate the dynamics of the system and how they affect the biological communities and, more importantly, if those factors are subject to human exploitation, like water abstraction activities (Correia et al, 2012;Félix et al, 2013a).…”

“…The marine colonization of landlocked coastal lagoons with periodic openings to the sea occurs essentially during these openings, after which diversity is mainly determined by the plasticity of the species, based on their tolerance to variations of environmental factors. The colonization by freshwater macroinvertebrate species, mainly aquatic insects, also occurs in these lagoons and depends mostly on less constant abiotic factors, like salinity, which varies considerably on both temporal and spatial scales (Cancela da Fonseca et al, 1989;Correia et al, 2012;Beer & Joyce, 2013;Félix et al, 2013a).…”