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The Indo-Pacific gastropod Terebralia palustris is particularly suitable for comparing natural and anthropogenic induced taphonomic pathways due to its wide geographic distribution and common presence within archeological context. The present study aims to (1) correlate shell architecture and morphology with fragmentation pattern and preservation, (2) quantify taphonomic changes to differentiate between natural vs. anthropogenic preservation features, (3) provide a guideline for analyzing fragmented shell remains in archeological material. Shells and taphonomic features were studied from both recent mangrove environments from the Emirate of Sharjah, United Arab Emirates as well as archeological material within the Iron age II site (1000–600 BC) of Muweilah near the City of Sharjah. Techniques utilized include morphometry, thin sectioning, scanning electron microscopy (SEM) of recent specimens and a semi—quantitative taphonomic analysis of anthropogenic material. Thin sectioning shows a complex internal shell morphology with a tripartite subdivision of shell layers. The recent material shows better preserved features on both the exterior and internal shell surfaces than the highly fragmented material recovered from the archeological context, which shows a distinct size distribution as well as showing higher levels of surface abrasion, surface cracks and color alterations. These features are correlated to extraction techniques, cooking methods and waste disposal handling. [ABSTRACT FROM AUTHOR]

Abstract Interest in the systems supplying dissolved forms of iron to the sea from upland forests and wetlands has increased because iron is abundant on land but has low bioavailability in seawater. This can be a limiting factor for the growth of marine phytoplankton. Organic complex iron, a typical form of iron dissolved in seawater, is supplied to the ocean through rivers from forest and wetland soils. As a related study, we focus on mangrove ecosystems located at the boundary between the land and sea and on polyphenols present in leaves as ligands for the formation of iron complexes. When mangrove leaf litterfalls on the wet forest floor, phenolic compounds leach out from the leaves and might solubilize insoluble iron in the sediments (i.e., iron complexation). However, the reaction mechanism is not simple in the field, and it might be made more complex by tidal currents and intervention by crabs and snails, which consume mangrove leaf litter. In the present study, we focused on a detritivorous snail, Terebralia palustris, as a facilitator of iron solubilization associated with phenolic compounds, and examined how the snail contribute to iron solubilization processes. Our results indicated that the amounts of phenolic compounds in mangrove sediments are strongly related to iron solubilization. Furthermore, the average dissolved iron and phenolic contents in sediments from areas inhabited by the snail were significantly higher than those of sediments where the snail was not present. We additionally report that the solubilization of iron was promoted when snail feces were added to mangrove sediments. In conclusion, we propose that iron solubilization in mangrove sediments is promoted by the interaction between i) iron in the sediment, ii) phenolic compounds derived from mangroves, and iii) the consumption of leaves and the deposition of feces by the snail.

Interest in the systems supplying dissolved forms of iron to the sea from upland forests and wetlands has increased because iron is abundant on land but has low bioavailability in seawater. This can be a limiting factor for the growth of marine phytoplankton. Organic complex iron, a typical form of iron dissolved in seawater, is supplied to the ocean through rivers from forest and wetland soils. As a related study, we focus on mangrove ecosystems located at the boundary between the land and sea and on polyphenols present in leaves as ligands for the formation of iron complexes. When mangrove leaf litterfalls on the wet forest floor, phenolic compounds leach out from the leaves and might solubilize insoluble iron in the sediments (i.e., iron complexation). However, the reaction mechanism is not simple in the field, and it might be made more complex by tidal currents and intervention by crabs and snails, which consume mangrove leaf litter. In the present study, we focused on a detritivorous snail, Terebralia palustris, as a facilitator of iron solubilization associated with phenolic compounds, and examined how the snail contribute to iron solubilization processes. Our results indicated that the amounts of phenolic compounds in mangrove sediments are strongly related to iron solubilization. Furthermore, the average dissolved iron and phenolic contents in sediments from areas inhabited by the snail were significantly higher than those of sediments where the snail was not present. We additionally report that the solubilization of iron was promoted when snail feces were added to mangrove sediments. In conclusion, we propose that iron solubilization in mangrove sediments is promoted by the interaction between i) iron in the sediment, ii) phenolic compounds derived from mangroves, and iii) the consumption of leaves and the deposition of feces by the snail. [ABSTRACT FROM AUTHOR]

Gastropods are integral components of mangrove ecosystems as they retain primary carbon by consuming leaf litter. However, alternative primary sources may make a significant contribution toward the diets of primary consumers in subtropical mangroves due to seasonal processes that impact the availability and nutritional quality of the leaf litter. The variability of the dietary niche for the giant mangrove whelk Terebralia palustris was investigated using a stable isotope approach (δN and δC) in conjunction with gut contents analysis. The size of the isotopic niche for T. palustris was different between November (summer) and July (winter). Isotopic niches were larger in July, indicating higher dietary diversity. There was no overlap between isotopic niches of different-sized T. palustris, which indicates robust resource partitioning and an ontogenetic dietary shift. The C:N ratio of mangrove leaf litter ranged from 59.34 ± 0.9 in November to 201.66 ± 4.5 in July. The high C:N ratio observed in July could be driving the dietary diversification, if T. palustris preferably consumes more nutritious sources such as microphytobenthos. The variability in the diet of T. palustris is important when considering the ecological role of this species, as a link between mangrove primary productivity and higher trophic levels. [ABSTRACT FROM AUTHOR]

We investigate the local marine reservoir effect at Kalba, United Arab Emirates (UAE), between the Neolithic and Bronze Age with respect to possible changes through time and mollusk species diversity. Two distinctive species living in close proximity to the mangrove of Khor Kalba provide insights into ocean circulation patterns in this coastal environment. The species selected are the bivalve Anadara uropigimelana , and the gastropod Terebralia palustris. They have been an important local food resource for humans since at least the Neolithic. Our results show that for the Neolithic and Bronze Age, the reservoir effects ΔR are quite different for the species selected. For Anadara spp. the ΔR decreases from 576 ± 90 to 112 ± 44 years, while for Terebralia spp. the reduction ranges from 389 ± 66 to −19 ± 36 years. These results are coeval with other multi-proxies (stalagmite records and sea level changes) for the middle Holocene, and suggest that the main cause of the decreasing reservoir effect is a changing – in this case declining - sea level and an increasingly drier climate. [ABSTRACT FROM AUTHOR]

Mangrove gastropods and hermit crabs are frequently harvested for use as bait by artisanal trap and hook fishers, along the Kenyan coastline and elsewhere. In addition to mangrove degradation, the harvesting of shelled invertebrates, can alter shell availability and hence survival of these interdependent fauna. This study compares shell morphometric characteristics such as shell availability, adequacy and bait yield, among sites with different patterns of bait harvesting and other human disturbances. Shell morphometrics are also related to mangrove forest stand characteristics such as forest complexity, dominance, cutting intensity and sapling regeneration. Results indicate that the sampling regime, hermit crab taxa and mangrove zone influence morphometric characters of the gastropod and hermit crab. Significantly higher (P < 0.001) shell availability, adequacy and bait yield of the predominant hermit crab, Clibanarius danai, are recorded at upper and mid forested zones of sites with robust forest. This was attributed to shell selectivity of the crab, coupled with constancy of the environment at closed canopy sites. Apparently, forest structure is an important determinant of shell utilization patterns compared to prevailing bait harvesting activity. Protection of robust upper mangrove forest zones may therefore enhance sustainability of shelled bait harvesting and consequently the livelihoods support emanating from bait fishery. [ABSTRACT FROM AUTHOR]

Terebralia palustris(Linnaeus, 1767), the giant mangrove whelk, is a prominent component of mangrove ecosystem malacofauna in the Indo-West-Pacific region. On the east coast of Africa, the range ofT. palustrisextends from Kenya to the south-eastern region of South Africa. Here we confirm reports that, in the past three decades, South African populations ofT. palustrishave declined.Terebralia palustriswas recorded from only two estuarine mangrove forests during a survey conducted in 2013/2014, compared with six estuaries in the mid-20th century. At Kosi Bay, the average density was 186 ind. m-2(SD 106) in comparison to only 7.1 ind. m-2(SD 2.5) at Durban Bay. Additionally, the average shell height of individuals at Durban Bay (60.3 mm; SD 13.6) was larger than at Kosi Bay (31.84 mm; SD 16.09), indicating the absence of juvenile snails at Durban. In South Africa there have been no previous ecological assessments forT. palustrisand, aside from one detailed survey in the early 1960s, most of the occurrence records are vague and incomplete. The ultimate causes for the decline of this charismatic gastropod in South Africa are unknown, although habitat loss and degradation are suspected. Further research is urgently required, particularly into aspects concerning its disappearance at the limit of its global distribution. [ABSTRACT FROM AUTHOR]

The first season of archaeological surveys carried along the shores of Lake Siranda (Las Bela, Balochistan) in January 2011 has shown the presence of two prehistoric shell middens characterised by fragments of mangrove and marine shells as well as chipped stone artefacts. The shell middens were AMS dated to the middle Holocene by one single specimen of Terebralia palustris gastropod. Their presence indicates that mangrove environments exploited by groups of shellfish gatherers existed in the area at least since the above period, and that the present-day lake depression was in fact a shallow tidal lagoon of the Arabian Sea, the shores of which had been settled at least during part of the Neolithic. [ABSTRACT FROM AUTHOR]

The effect of different sewage concentrations (0, 20, 60 and 100%), vegetation (Bare, Avicennia marina or Rhizophora mucronata) and immersion periods (immersion/emersion period of 12/12 h or 3/3 days just for 100%) conditions were studied for 6 months on survival and growth rates of Terebralia palustris (Linnaeus, 1767). Gastropods' activity and ecosystem engineering preformed at bare and A. marina planted cells and 3 sewage conditions (0, 20 and 60%) were determined. Survival rates were higher than 70% in all treatments. Growth rate decreased significantly with increasing sewage concentrations (mainly at unplanted conditions) and longer immersion periods. A complete shift (from immersion to emersion periods) and a significant decrease in mobility and consequently its engineer potential, due to sewage contamination, lead to a 3–4 fold decrease in the amount of sediment disturbed. Sewage contamination, primary producers' abundance and environmental conditions may have influenced the gastropods survival, growth and its ecosystem engineering potential. [Copyright &y& Elsevier]

Abstract: Population structure and distribution of Terebralia palustris were compared with the environmental parameters within microhabitats in a monospecific stand of Avicennia marina in southern Mozambique. Stable carbon and nitrogen isotope analyses of T. palustris and potential food sources (leaves, pneumatophore epiphytes, and surface sediments) were examined to establish the feeding preferences of T. palustris. Stable isotope signatures of individuals of different size classes and from different microhabitats were compared with local food sources. Samples of surface sediments 2.5–10m apart showed some variation (−21.2‰ to −23.0‰) in δ 13C, probably due to different contributions from seagrasses, microalgae and mangrove leaves, while δ 15N values varied between 8.7‰ and 15.8‰, indicating that there is a very high variability within a small-scale microcosm. Stable isotope signatures differed significantly between the T. palustris size classes and between individuals of the same size class, collected in different microhabitats. Results also suggested that smaller individuals feed on sediment, selecting mainly benthic microalgae, while larger individuals feed on sediment, epiphytes and mangrove leaves. Correlations were found between environmental parameters and gastropod population structure and distribution vs. the feeding preferences of individuals of different size classes and in different microhabitats. While organic content and the abundance of leaves were parameters that correlated best with the total density of gastropods (>85%), the abundance of pneumatophores and leaves, as well as grain size, correlated better with the gastropod size distribution (>65%). Young individuals (height<3cm) occur predominantly in microhabitats characterized by a low density of leaf litter and pneumatophores, reduced organic matter and larger grain size, these being characteristic of lower intertidal open areas that favour benthic microalgal growth. With increasing shell height, T. palustris individuals start occupying microhabitats nearer the mangrove trees characterized by large densities of pneumatophores and litter, as well as sediments of smaller grain size, leading to higher organic matter availability in the sediment. [Copyright &y& Elsevier]

A pioneer survey of the Red Sea Coast of Eritrea revealed three shell middens dated to the mid-Holocene that reflect the exploitation of different coastal environments. Misse East and Gelalo Northwest were both dated to the eighth millennium BP. The former is dominated by Atactodea striata, a small bivalve that burrows in intertidal sands, the latter by Terebralia palustris, a large gastropod living in mangrove swamps. Gelalo Northwest also included a relatively large number of shell beads. Asfet, dated to the sixth millennium BP, was also dominated by Terebralia palustris. This coastal settlement is probably the result of adverse climatic conditions that prevailed in the hinterland during that period. Change in the regime of monsoons in the Sahara and northeast Africa may have caused human populations to settle in better-watered areas, the Red Sea Coast among them, and to adapt to the new conditions by exploiting the marine environment. [ABSTRACT FROM AUTHOR]

Abstract: Terebralia palustris is a common mud-whelk present at a particularly high density in all Indo-West Pacific mangroves. Young snails feed on nothing but mud while larger specimens are able to feed on fallen leaves too. In Kenya (Mida Creek) under the canopy, competition for mangrove leaves can be very high due to the high density of Sesarmidae crabs. On open exposed muddy platforms, no Sesarmidae occur but the leaf density is very low because the leaves are only randomly present as they are deposited and removed twice a day by the tide. However, the snail density is always very high, raising the question as to whether the snails use a special searching strategy to optimize their resource finding rather than a purely random movement. By analyzing the snails'' movements on a uniform area at different levels and comparing them with simulated random paths, we could show that the snails'' movements are not purely random. The distribution of different size classes of T. palustris in Mida Creek was known to be quite odd: the same simulation approach suggests that the zonation asymmetry could reasonably be due to the stochastic recruitment of juveniles in space and time and maintained by a substantial long-lasting spatial inertia. [Copyright &y& Elsevier]

Abstract: The gastropod Terebralia palustris often dominates the surface of muddy to sandy substrates of intertidal mudflats and mangrove forests, where they clearly destabilize the sediment. In the present study, it was investigated whether and to what extent the behaviour of juvenile and adult snails differs among habitats (mudflat vs. mangrove stand) in a Sonneratia alba mangal at Gazi Bay, Kenya. For this purpose we: (1) examined their distribution along three land–sea transects; and (2) applied stable isotope analysis to determine the feeding patterns of different-sized snails from the mangrove and mudflat habitats. Additionally, we investigated if these gastropods exert an impact on microphytobenthic (diatom) biomass, and whether this is size-dependent. The latter objective was met by either enclosing or excluding different-sized snails from experimental cages on the intertidal mudflat and the subsequent assessment of a change in pigment concentration of the sediment surface. In agreement with several previous studies conducted in other mangroves and geographical locations, a spatial segregation was demonstrated between juveniles (more common on the mudflat) and adults (more common in the mangrove forest). On the intertidal mudflat juveniles avoided sediment patches characterized by highly saline water in intertidal pools and a high mud content, while adults tended to dwell on substrates covered by a high amount of leaf litter. Stable carbon isotope analysis of the foot tissue of snails sampled from the S. alba stand and the mudflat indicated a transition in food source when a shell length of 51mm is reached. Considering the δ 13C value of juveniles, it seems they might be selecting for microphytobenthos, which might explain their preference for the mudflat. The diet of size classes found in both habitats did not differ significantly, although juveniles inhabiting the mangrove forest were slightly more depleted in 13C compared to those residing on the mudflat. Assuming juveniles feed on benthic microalgae and considering the lower microalgal biomass inside the mangrove forest, this may be a consequence of a higher contribution of other, more 13C depleted organic carbon sources, like phytoplankton, to their diet. Experimental results indicate a negative, but insignificant, impact on benthic diatom biomass by juveniles (due to grazing) and adults (due to physical disturbance). This finding seems to be in agreement with the results of the stable carbon isotope analysis, strongly suggesting the selective feeding of juvenile T. palustris on benthic diatoms. [Copyright &y& Elsevier]

The gastropod Terebralia palustris (Linnaeus) is one of the largest prosobranchs found in tropical intertidal habitats. The adults form feeding aggregations and frequently dominate the surface of muddy substrates, where they clearly destabilize the sediment surface. We tested the following hypotheses: 1. The gastropod has negative effects on the density of infaunal animals because of potential food competition and/or surface sediment disturbance. 2. The disturbance exerted by T. palustris results in more variable infaunal assemblages, especially where intensity of disturbance is high. To address these hypotheses gastropods were either enclosed or excluded from experimental cages, which were randomly assigned to blocks as far as 300 m apart on an intertidal mudflat in East Africa. After nine weeks of enclosure the gastropod at high densities clearly affected the meiofauna assemblages. Several meiofauna groups were found in significantly reduced densities in the presence of the gastropod compared with control cages without the gastropods, supporting our primary hypothesis. In cages without T. palustris a cyanobacterial carpet developed while this was not evident in enclosure cages. T. palustris had no significant impact on the macrofauna assemblage. In support of our second hypothesis, multidimensional scaling ordination (MDS) suggested that there was an increased variability of meiofauna within cages with high density of T. palustris. [ABSTRACT FROM AUTHOR]

The growth stages of Trebralia palustris can easily be distinguished by the presence of a varix on the last whorl and the shape of the outer lip. In a T. palustris population in the mangal of Iriomote Island, southern Japan, juveniles are the most abundant and sub-adults are the least abundant. The mean size of sub-adults is not different from that of adults in sites with similar environmental conditions, but the mean sizes differ in different life environments. Sub-adult and adult snails in a well-developed mangrove stand of Rhizophora stylosa and Bruguiera gymnorrhiza with rich food resources are larger than those in a rather open stand of short Avicennia marina trees with comparatively poor food resources. The size of snails positively affected some population traits such as fecundity and the grazing rate of mangrove litter. [ABSTRACT FROM AUTHOR]