Burrowing activity of the Neohelice granulata crab (Brachyura, Varunidae) in southwest Atlantic intertidal areas

Abstract

The burrowing and semiterrestrial crab Neohelice granulata actively and constantly builds its burrows in the intertidal zone of the Bahía Blanca Estuary during low tide. Differences in structural morphology of N. granulata burrows and burrowing activities in contrasting microhabitats (saltmarsh and mudflat) were analyzed and related to several conditions, such as tide level, substrate type, sediment properties, and population density. In the mudflat the higher density of total burrows in autumn (172 burrows•m-2) was associated with molt timing, and the higher density of active burrows in summer (144 burrows•m-2) was associated with reproductive migration. Sediments from biogenic mounds (removed by crabs) showed higher water content and penetrability than surface sediments (control), suggesting that bioturbation increases the values of these parameters. Grain size distribution profiles and mineralogical composition did not vary between microhabitats or between seasons. Burrows were all tunnel-shaped and only those from the saltmarsh had chambers inside the tunnels, possibly used for reproductive purposes. Burrows from the saltmarsh had narrow entrances and deep tunnels, and burrows from the mudflat presented very narrow entrances and surface tunnels. Differences in burrow features and burrow activity of N. granulata between microhabitats were confirmed and associated with biotic and abiotic factors, indicating that this species has an adaptive burrowing behavior.

Invertebrate zoogeomorphology: A review and conceptual framework for rivers

“…Considerable research has considered vertical burrows (Kristensen et al, 2012; Figure 1b,c), such as those constructed by isopods and crabs in estuarine environments (e.g., Escapa et al, 2007; Smith & Green, 2015; Talley et al, 2001; Wilson et al, 2012). For example, burrows of the crab Neohelice granulata can exist in densities of 172 burrows m −2 (Angeletti et al, 2018) and remove up to 147.5 g d −1 of sediment per burrow (Iribarne et al, 1997). Vertical crab burrows have thus been associated with accelerated marsh creek formation through the exclusion of stabilizing vegetation, and directly by destabilizing sediment (Escapa et al, 2007), with the associated creek development hypothesized to mitigate the effects of sea level rise on saltwater incursion (Vu et al, 2017).…”

Study of structural properties of acid-treated natural sediment and its application as a sustainable catalyst

“…Prior to the activation process, the organic matter was removed from the starting natural sediment (S0) with hydrogen peroxide at 130 volumes, initially cold and then hot (333 K) until bubbling had ceased (Angeletti et al 2018). Then, the solid was washed with distilled water and treated in vacuum at 353 K for 24 h to remove the adsorbed water.…”

Environmental stressors induced strong small-scale phenotypic differentiation in a wide-dispersing marine snail

“…One possible explanation for the low density in marshes, relative to flats, is if this resulted from a negative interaction between H . australis and the grapsid crab Neohelice granulata , whose aggregation is also facilitated by marsh plants (Spivak et al 1994, Alvarez et al 2013, Angeletti et al 2014, Angeletti & Cervellini 2015) where it attains density peaks in late spring and early summer but it is absent throughout the year in unvegetated areas (flats or pans; (Angeletti & Cervellini 2015). It is therefore likely that the low density of H .…”

“…On the one hand, the grapsid crab Neohelice granulata is one of the most abundant macroinvertebrates of intertidal areas of the SW Atlantic estuaries where it commonly inhabits the upper vegetated area (marshes) but uses the entire intertidal zone (Spivak et al 1994, Alvarez et al 2013, Angeletti et al 2014, Angeletti & Cervellini 2015). This burrowing crab could exert a strong pressure on Heleobia australis since it can drastically reduce snail density in vegetated areas due to an intense bioturbation activity (Spivak et al 1994, Alvarez et al 2013, Angeletti et al 2014, Angeletti & Cervellini 2015) and/or through snail predation (D’Incao et al 1990, Barutot et al 2011). On the other hand, parasite pressure also differs along the intertidal zone.…”