Aquatic Coleoptera and Hemiptera assemblages in three coastal lagoons of the NW Iberian Peninsula: assessment of conservation value and response to environmental factors

Abstract

ABSTRACT1. The objectives of the present study were to describe and analyse the composition and structure of aquatic Coleoptera and Hemiptera assemblages in three coastal lagoons of north-western Spain during a one year cycle, in order to evaluate their relative adequacy to provide information about the conservation value of lagoonal habitats and sites. The lagoons are designated as Special Areas of Conservation (SAC) under the European Union Habitats Directive and two of them are also protected by the Ramsar Agreement. Several abiotic variables, including salinity, were recorded at the time of sampling.2. In total, 67 species (52 Coleoptera and 15 Hemiptera) and 6568 adult individuals (2664 Coleoptera and 3904 Hemiptera) were collected. In all pair-wise comparisons Kendall's coefficients of concordance between lagoons were higher for Hemiptera than for Coleoptera, indicating that Hemiptera assemblages were more similar across sites.3. Most species recorded had a wide Palearctic distribution and only three species of water beetles could be considered endemic to Iberia: Hydroporus vagepictus, Hydroporus vespertinus and Hydrochus angusi. Similarly, the species collected had a widespread distribution in the Iberian Peninsula as the only species considered to be rare taxa at this scale were Hydrochus angusi and Cymbiodyta marginella among the Coleoptera and Sigara scotti and Notonecta glauca glauca among the Hemiptera.4. The results do not support the idea of distinct aquatic insect assemblages for coastal lagoons in the Iberian Peninsula. Comparisons of the numbers of interior (non-coastal) and coastal provinces of the Iberian Peninsula where the species had been recorded showed they had been recorded in a larger proportion of interior provinces.5. Salinity seemed to reduce species richness in both groups while the results of a canonical correspondence analysis (CCA) showed that the majority of species responded negatively to salinity.6. This study suggests that species richness and rarity of aquatic insect assemblages may underestimate the conservation value of lagoonal habitats because their net contribution to catchment biodiversity is likely to be low.

Biodiversity and Conservation of Coastal Lagoons

“…The response of beetles and bugs to the increase in conductivity seemed to define, at least, the species typical of sites with high values of this variable. Some species respond negatively to high conductivity (Garrido & Munilla, 2008), while others are adapted to sudden changes in this variable and can be considered tolerant. In this sense, ordination analysis identified a group of tolerant species (i. e. Berosus hispanicus, Rhantus suturalis and Sigara stagnalis), typical of habitats with high conductivity or salinity values (Arnold & Ormerod, 1997;Garrido & Munilla, 2008; www.intechopen.com Hansen, 1987;Martinoy et al, 2006).…”

“…Salinity was only measured in 1998. As the salinity and conductivity values were highly correlated (r= 0.994) (Garrido & Munilla, 2008) and as this variable provides redundant information we decided not to measure it in 2008.…”

“…heathlands and pine (Pinus pinaster Ait.) forests in a densely populated rural setting (Garrido & Munilla, 2008). …”

“…In this sense, the composition and abundance of benthic invertebrates is one of the most important criteria to be considered. Little is known of the communities of aquatic insects in coastal lagoons, especially when compared with freshwater ecosystems (Garrido & Munilla, 2008). Within this group of organisms are Coleoptera and Hemiptera, two of the most common groups in these environments.…”

“…To complement the biological data, several abiotic variables were recorded at the same time as fauna was sampled. The data corresponding to 1998 had already been published in Garrido & Munilla (2008). The areas where these lagoons are located had suffered an increasing anthropogenic impact in recent years, mainly due to the expansion of tourist areas.…”