Nerita Undata Research Articles

Relative predation intensity of an intertidal gastropod on artificial coastal defense structures.

Despite seawalls becoming ubiquitous coastal features, and having some physical similarities to natural rocky shores, it remains unclear how these urban habitats influence predator-prey interactions. Predators can affect intertidal mobile prey densities through two pathways: (1) successful predation directly influences prey mortality rates, and (2) direct and indirect effects of predation can scare and induce motile prey to seek safer areas. In this study, we investigated whether intertidal predators affect the density of the marine gastropod, Nerita undata, at four seawall sites in Singapore. Using a tethering method that we developed, we monitored the mortality and other evidence of predation (shell state) of tethered N. undata. Field experiments revealed high (22.5%-82.5%) predation potential of N. undata across the four sites, with significantly higher predation risk at lower shore heights and for snails with mixed shell coloration. Observations and analysis of the shell state after 3 days showed that predation on seawalls was primarily by crushing predators such as fish. Other predators of N. undata include predatory snails, with various feeding methods that left behind different predator signatures. Our results add substantially to the limited knowledge on predator-prey interactions on seawalls, particularly for Nerita undata, and suggest that seawall systems are more dynamic than previously thought. This further highlights the role of these artificial structures as important habitats and feeding grounds in urban coastal ecosystems.

Gastropod Species Diversity in The Mangrove Bale Area of Poton Bako East Lombok

Gastropoda is a class with the biggest number of species, since a class of Mollusca phylum is generally effectively adjusted to different sorts of marine and freshwater territories to earthbound conditions. So a study was conducted on the diversity of Gastropoda species in the Bale Mangrove Poton Bako East Lombok area with the aim of knowing the types of gastropods that exist in the area. The method used in this study is the quadrat transect method. The results of research on the diversity of gastropod species in the Bale Mangrove Poton Bako East Lombok area found 6 species of Gastropoda including Cerithidea sp, Telebralia sulcata, Nerita undata, Telescopium telescopium, Chicoreus capucinus, Indothais gradate. The average diversity index value of the three stations is H′ = 1.41262991 which means that the diversity of Gastropods in the Bale Mangrove Poton Bako Area of East Lombok is moderate diversity.

Struktur Komunitas Gastropoda pada Kawasan Mangrove Pantai Gerupuk Lombok Tengah

he purpose of this study was to determine the community structure and distribution pattern of gastropod in the mangrove area of Gerupuk Beach, Central Lombok. The field survey was conducted using the quadratic transect method and free collection in October-November 2022. The purposive random sampling was used in this study. The results showed there were 591 individuals Gastropod in all stations consisted of 4 species of Gastropod 7 families, namely Assimenia brevicula, Cassidula aurifelis, Cassidula nucleus, Littoraria carnifera, Littoraria angulifera, Littoraria scabra, Nerita undata, Cerithidea alata, Cerithidea quoyii, Telescopium Telescopium, Terebralia sulcata, Terebralia sp., Chicoreus capucinus and Nassarius reevanus. The highest abundance was found at station III with a value of 1.48 individuals per m2, where the highest abundance of gastropod species was Cerithidea alata. The diversity (H ') obtained from the three stations ranged from 1.476 to 1.996 which was categorized as medium level. Evenness index (E) from of 0.559-0.756 which were in the relatively even category. Furthermore, Domination index (C) of Gastropods range from 0.255-0.355 for low dominance. Gastropod distribution patterns in the Gerupuk Beach mangrove ecosystem are clustered and uniform. It is concluded that based on the biological indices the structure of the Gastropods community in the mangrove area of Gerupuk Beach it was in normal condition.

Mangrove Ecosystem Services in Mitigation for Mollusca Communities in Lembar Sheet District, West Lombok Regency

Mangroves have an important role in mitigation and a significant contribution to the wealth of macrofauna. The success of mangrove management has significantly affected the diversity of macrofauna which are associated biota. The research objectives were to investigate the composition of mangroves and mollusc communities, the ecological conditions of the waters, and evidence of mangrove ecosystem services in mitigation. The research data sources are faunal, ecological, and social data. The research method uses purposive sampling and data analysis using descriptive statistics. The results showed that 7 mangrove species were found in the Cemare mangrove area. Avicennia marina, Bruguiera gymnorriza, Ceriops tagal, Rhizophora apiculata, Rhizophora mucronata, Rhizophora stylosa, and Sonnetaria alba. The dominant mangroves were Rhizopora stylosa (201 ind/Ha) and Rhizopora apiculata (146 ind/Ha). Meanwhile, the highest abundance of mollusc species was obtained by Cerithidea cingulate (38.94%) and Nerita undata (29.20%) from the gastropod class, while from the Bivalvia class, Anadara grandis (36.07%) and Anadara granosa (19.67%) were found). The condition of the aquatic environment at the research site is still within the tolerance range required for the growth and development of mollusk species. Furthermore, the majority of respondents know or are aware that mangroves have an ecological function (habitat/habitat for animals), an economic function (a livelihood location), a physical mitigation function (abrasion resistance), a non-physical mitigation function (reducing environmental heat) Good category. These results indicate that efforts need to be made to increase mangrove revegetation, given its significant benefits in mitigation.

Behaviour broadens thermal safety margins on artificial coastal defences in the tropics

Tropical species are predicted to be among the most vulnerable to climate change as they often live close to their upper limits to thermal tolerance and in many cases, behavioural thermoregulation is required to persist in the thermal extremes of tropical latitudes. In concert with warming temperatures, near-shore species are faced with the additional threat of shoreline hardening, leading to a reduction in microhabitats that can provide thermal refuges. This situation is exemplified in Singapore, which lies almost on the equator and so experiences year-round hot temperatures, and much of its coastline is now seawall. To investigate the thermal ecology of a common intertidal gastropod, Nerita undata, on these artificial structures, we measured thermal conditions on two seawalls, the temperatures of habitats occupied by the snail, and compared these with the snail's thermal tolerance by measuring heart rate and behavioural thermoregulation (as preferred temperature, Tpref). At one of the two seawalls (Tanjong Rimau), temperatures experienced by N. undata exceeded all measures of thermal tolerance in the sun, while at the other (Palawan Beach), they did not. Temperatures in habitats occupied by the snails on the seawalls were similar to their measured Tpref in the laboratory and were lower than all measures of thermal tolerance. Behavioural thermoregulation by the snails, therefore, significantly increased the thermal safety margins of N. undata on the relatively homogenous seawalls in Singapore, and at one of the two seawalls were necessary to allow snails to survive. Accordingly, to facilitate motile species to maintain broad thermal safety margins through behavioural regulation, the provision of additional refuges from thermal stress is recommended on artificial coastal defences such as seawalls.

Species composition and abundance of seashells in the intertidal zone of Tubalan cove, municipality of Malita, Davao occidental province, Philippines

The study determined the seashells’ species composition, relative abundance, population density, species diversity, substrate types and the gleaners’ socio economic-profiles in the intertidal zone of Brgy. Tubalan, Municipality of Malita, Davao Occidental Province, The Philippines. Eight seashell species were identified in the study area namely: Anodontia edentula, Anadara antiquata, Cerastoderma edule, Lutraria australis, Nerita undata, Paphia amabilis, Strombus urceus and Terebralia sulcata. Among the stations, Cerastoderma edule had the highest number of relative abundance with 35.42 in Station 2, while the Anodontia edentula with 5.21 is exhibited lowest value (Station 1). For population density, the highest value was with Cerastoderma edule accounted 55 individuals/m2, while the lowest is Anodontia edentula with 5 individuals’ species/m2. In terms of species diversity, Station 2 had the highest number with 3.737, and the lowest was in Station 1 with 2.376. The result on the substrate type characterization revealed that fine sand to medium sand substrates were observed in all stations. Collected seashells by the local gleaners will usually sell it in their public market, others are in their neighbours. To most gleaners, gleaning activity is considered as their main source of income to sustain daily needs. Statistically, the T-test results revealed no significant differences for abundance with the value 0.795 and for population density with the value of 0.379 among the two stations; this implies that tabulated value of 0.05 is lesser than the calculated value. For the number of species in relation to abundance with 0.03 and population density with 0.023, tabulated value of 0.05 was greater than the calculated value which implies that the null hypothesis on the number of species in terms of abundance and population density among two stations was rejected. It is recommended to conduct further study in other barangays, highlighting the inclusion of physico-chemical parameters factors affecting species composition and abundance of seashells.

Qualitative Protein Hydrolyzed from Nerita undata in supralittoral rocks and mezolittoral zone of Hasa Cape using TLC

Gastropods are the sources of protein for coastal communities in the Maluku islands. We conducted analysis quantitative and qualitative of protein in Nerita undata meat from Hasa Cape in Saparua Island. The percentage of protein was analyzed by the Kjeldahl method. Qualitative analysis began with breaking peptide bonds in protein to amino acid components by sulphuric acid and barium hydroxide hydrolyzed. We identified amino acid compounds by using thin-layer chromatography (TLC) in butanol-acetic acid-water (8:1:1, v/v) as eluent. The result showed that N. undata meat contains 11.15% of protein and twelve amino acid compounds. There are seven essential amino acids in N. undata meat from supralittoral rocks and mezolittoral zone of Hasa cape is a source of quality protein. Thus, this species can be considered as a source of high-quality protein.

Qualitative Protein Hydrolyzed from Nerita undata in Supralittoral Rocks and Mezolittoral Zone of Hasa Cape Using TLC

Qualitative Protein Hydrolyzed from Nerita undata in Supralittoral Rocks and Mezolittoral Zone of Hasa Cape Using TLC

Preliminary study on diversity of intertidal gastropods in Barangay Day-asan, Surigao City, Philippines

Unregulated harvesting and habitat degradation of marine gastropods are major anthropogenic activities done by the local people in Barangay Day-asan, Surigao City, Philippines. This study was undertaken to determine the diversity of marine gastropods found in the intertidal of Dapya Island. Collection of specimens was done through hand picking and beachcombing methods in the three established study stations. Data revealed a total of 184 individuals belonging to 37 species in 5 orders, 15 families and 25 genera. The order Neogastropoda obtained the highest number of species with 15 species, followed by order Mesogastropoda with 10 species, order Archaeogastropoda with 7 species, order Neritopsina with 4 species and order Caenogastropoda. Among the 37 species, Nerita undata was the most abundant. Shannon-Weiner diversity index revealed that station 2 (H=1.193) obtained the highest species diversity, followed by station 3 (H= 1.103) and station 1 (H=1.063). The Bray-Curtis analysis of species composition showed two different clusters of habitat. Cluster 1 is composed of two related habitats joined by Stations 1 and 2 with Si= 54.26% and cluster 2 composed of Stations 3 and 1 with Si= 40.65%. Furthermore, among the 37 species, six of which were concordant in all study stations viz., Angaria delphinus, Astralium calcar, Conus miles, Lambis lambis, Euprotomus bulla and Canarium labiatum. The results of the study showed a low diversity of intertidal gastropods in Barangay Day-asan. The area is known to be the most gleaned by locals and it is been already disturbed due to overharvesting of gastropod species.

The spesies composition and distribution pattern of Gastropod at Forrest Mangrove Block Bedul Segoro Anak, Alas Purwo National Park

This research aims to determine the spesies compossition and distribution pattern of Gastropod and its relationship with abiotic factors (pH, salinity, soil texture, and organic content of the soil, and the high of tide of the eustuary area) in the Mangrove forest at Blok Beduk Segoro Anak Alas Purwo National Park. This research was conducted on February 2013. Data was taken four times using a week time interval during one month. Every observation covered eight stations, where station 1 to station 4 consist of four transects and 40 plots, while station 5 to station 8 consist of 3 transects with 42 plots and each plot was 5 m × 5 m. Gastropod observed from each plot are preserved with 70% alcohol and identified in Malakologi Laboratory, Indonesian Institute of Sciences (LIPI). Results of the research reveated that the Gastropod observed consist of 19 families and 37 species, and the dominant family is Ceritidae. The Diversity index of Shanon Wiener was 0.53 (low deversity). Two available of Distribution pattern, group (Canarium labiatum, Cassidula nucleus, Cerithium coralium, Chicoreus brunneus, Cassidula vespertilionis, Cerithidea cingulata, Cerithidea quadrata, Chicoreus capucinus,Conus rattus, Conus striolatus, Ellobium aurisjudae, Littorina carinifera, Littorina scabra, Monodonta labio, Nassarius melanoides, Nassarius olivaceus, Nerita balteata, Nerita planospira, Nerita undata, Pugilina ternatana, Sphaerassiminea miniata, Telescopium telescopium, Terebralia sulcata, Thais intermedia), random (Angaria delphinus, Conus catus, Conus omaria, Cymatium moniliferum, Erronea errones, Oliva oliva, Polinices aurantius, Pollia undosa, Tectus pyramis, Trochus californicus, Turbo argyrostoma). The abiotic factors had relatianship not significantly (p = 0.067) on Gastropod distribution pattern. Keywords : Distribution pattern,Gastropod, species compossition

Biochemical Change at the Setting-up of the Crossed-Lamellar Layer in Nerita undata Shell (Mollusca, Gastropoda)

Nerita undata is a marine gastropod, the shell of which consists of an external layer composed of very fine, long and undulating calcite prisms, and of an internal aragonite crossed-lamellar layer. As for any Ca-carbonate shell, both layers are composite materials, resulting from the sub-micrometric association of organic macromolecules with the mineral phase. But at the transition between the two layers, in situ synchrotron-based mapping using μ-XANES spectroscopy performed at the S K-edge and SR-FTIR spectroscopy reveals that biochemical compositions change correlatively with the mineral phase, such as displayed by the distribution of sulfur-containing organic compounds (S-polysaccharides or S-amino acids) and organic molecular groups (amide I and II bands). These results highlight the complex change of secretory activity operated by the mineralizing tissue (the mollusk mantle) between these two parts of the shell, which is suspected to minutely control the setting-up of the crossed-lamellar microstructural pattern over the calcite prisms—A not so straightforward feature.

Confocal Raman microscope mapping as a tool to describe different mineral and organic phases at high spatial resolution within marine biogenic carbonates: case study on <i>Nerita undata</i> (Gastropoda, Neritopsina)

Abstract. Marine biogenic carbonates formed by invertebrates (e.g. corals and mollusks) represent complex composites of one or more mineral phases and organic molecules. This complexity ranges from the macroscopic structures observed with the naked eye down to sub micrometric structures only revealed by micro analytical techniques. Understanding to what extent and how organisms can control the formation of these structures requires that the mineral and organic phases can be identified and their spatial distribution related. Here we demonstrate the capability of confocal Raman microscopy applied to cross sections of a shell of Nerita undata to describe the distribution of calcite and aragonite including their crystallographic orientation with high lateral resolution (~300 nm). Moreover, spatial distribution of functional groups of organic compounds can be simultaneously acquired, allowing to specifically relate them to the observed microstructures. The data presented in this case study highlights the possible new contributions of this method to the description of modalities of Nerita undata shell formation, and what could be expected of its application to other marine biogenic carbonates. Localization of areas of interest would also allow further investigations using more localized methods, such as TEM that would provide complementary information on the relation between organic molecules and crystal lattice.

PATTERNS OF RELATIVE GROWTH IN TROPICAL NERITIDS, NERITA UNDATA, BASED ON OPERCULUM ANALYSIS

Growth is one of the important events in the life history of an organism beside reproduction. The objective of the present study was to evaluate the possibility of using the operculum to determine the growth pattern of tropical neritids (Nerita undata). Shell and operculum dimension were measured using a vernier caliper to the nearest 0.01mm. The results showed that there was a relationship between operculum dimensions (length and width) and shell, and it was also shown allometric growth pattern. The study also indicated the relationship between operculum dimension and the shell parameters.

Notes on the Nerita (Archaeogastropoda) populations of Aldabra Atoll, Indian Ocean

Nerita undata, N. plicata, N. polita, N. albicilla and N. textilis are common intertidal gastropods on Aldabra Atoll. Each species prefers a different level on the shore and/or different degrees of exposure to wave action. Patterns of zonation, population size-frequency structure and biomass are given. N. undata exhibits 2 distinct ecophenotypes. Normal types occur on expsed to moderately sheltered shores but are replaced by ‘type B’ in extremely sheltered conditions. Differences in shell morphology and population structure are also noted. Foraging by all species was confined to hours of darkness, generally at low tide. Activity of N. polita was induced slightly on overcast days. N. undata and N. textilis are cryptically coloured and often visible during the day. N. plicata is conspicuous, but is protected by a strong shell. N. polita and N. albicilla are often brightly and variably coloured, but both are concealed during daylight. No Nerita were found infected with trematodes, suggesting that the degree of infection was extremely low. Habitats of the Aldabran Nerita are compared with 3 species on Barbados, West Indies.