Raimundo Outerelo

Searching the soil: forensic importance of edaphic fauna after the removal of a corpse.

Abstract:  Arthropods at different stages of development collected from human remains in an advanced stage of decomposition (following autopsy) and from the soil at the scene are reported. The corpse was found in a mixed deciduous forest of Biscay (northern Spain). Soil fauna was extracted by sieving the soil where the corpse lay and placing the remains in Berlese–Tullgren funnels. Necrophagous fauna on the human remains was dominated by the fly Piophilidae: Stearibia nigriceps (Meigen, 1826), mites Ascidae: Proctolaelaps epuraeae (Hirschmann, 1963), Laelapidae: Hypoaspis (Gaeolaelaps) aculeifer (Canestrini, 1884), and the beetle Cleridae: Necrobia rufipes (de Geer, 1775). We confirm the importance of edaphic fauna, especially if the deceased is discovered in natural environs. Related fauna may remain for days after corpse removal and reveal information related to the circumstances of death. The species Nitidulidae: Omosita depressa (Linnaeus, 1758), Acaridae: Sancassania berlesei (Michael, 1903), Ascidae: Zerconopsis remiger (Kramer, 1876) and P. epuraeae, Urodinychidae: Uroobovella pulchella (Berlese, 1904), and Macrochelidae: Glyptholaspis americana (Berlese, 1888) were recorded for the first time in the Iberian Peninsula.

Colonisation patterns of supralittoral arthropods in naturally stranded wrack debris on Atlantic sandy beaches of Brazil and Spain

From an ecosystem perspective, wrack debris represents a key element for the maintenance of biodiversity and functioning of sandy beaches. Here, we characterised the colonisation patterns of supralittoral assemblages associated with wrack accumulations (seaweed and mangrove propagules) on multiple Atlantic sandy beaches (southern Brazil and south-western Spain). By using a manipulative field experiment, we sought to determine the temporal changes of the density, diversity and the structure of the whole community during the colonisation of wrack debris, and whether the colonisation patterns in response to the stranding of natural wrack debris were different on local (between beaches) and regional (between Atlantic regions) scales. Our results showed increases in density and diversity during the first 3 days after the stranding of seaweeds and mangrove-propagules debris. Moreover, wrack debris was promptly invaded by a wide range of species (i.e. talitrids, dipterans, coleopterans and spiders), although the colonisation pattern was slower in southern Brazil (16-day period) than in south-western Spain (3-day period). Wrack-debris characteristics (e.g. amount, degradation and composition) combined with biological strategies (e.g. trophic guilds and mobility) of supralittoral species could explain the different colonisation patterns in each Atlantic region. The temporal changes of wrack-associated fauna can have potential effects on the wrack-derived process and food-web structure on sandy beaches.