scholarly journals Recruitment of mud clam Polymesoda erosa (Solander, 1876) in a mangrove habitat of Chorao island, Goa

2011 ◽  
Vol 59 (2) ◽  
pp. 153-162 ◽  
Author(s):  
Sandhya Clemente ◽  
Baban Ingole

Habitat-specific settlement success results either from active habitat selection or differential mortality after non-selective settlement. The mud clam Polymesoda erosa (Solander, 1876) is an ecologically and economically important benthic invertebrate with high abundance in the mangrove forests of Chorao Island, Goa, India. A one-year study (Jul 2004-Jul 2005) was conducted to characterize the patterns of post-larval settlement and survival of P. erosa in the mangrove habitat. The mean density of settling post-larvae was 28 no.m-2 with a majority of settlers during Sept 04. The density of adult clams in the landward zone ranged from 7-12 no.m-2 (mean: 9 ± 6 sd; n=122). In the seaward region, adults were completely absent at the low tide level. Higher densities of juveniles observed at the low- and mid-tide levels were assumed to be due to frequent inundation which allowed the young individuals to feed adequately and attain the critical sizes at which vulnerability to physical and biological constraints is substantially reduced, whereas, at high-tide level, increased desiccation may account for the mortality of settlers. It is speculated that initially the settlers settle according to the hydrodynamic conditions for sedimentation; however, adult survival is affected by their recruitment in a suitable habitat (e.g. substrates near Avicennia sp.). Thus, habitat dependent viability during the post-settlement phase could be the best explanation for the non-random, patchy distribution of P. erosa observed in the Chorao mangrove swamp.

2020 ◽  
Author(s):  
Martina Rogers ◽  
◽  
Michael C. Sukop ◽  
Jayantha Obeysekera ◽  
Florence George ◽  
...  

2018 ◽  
Vol 6 (2) ◽  
pp. 11
Author(s):  
Jans D Lalita ◽  
Jety K Rangan

This research was found the ecological adaptive significance for their survivorship in mangrove microhabitat was as follow resting place, avoiding high tide, finding food, lying larvae, avoid sunshine, and hiding from predators. Significance of clumped distribution was taken to reduce drying stress, temperature, fallen from substrate against wave strikes, feeding and reproduction activity, suitable habitat. Significance of population abundance to balance strong predation and response to pressure of nature selection for their survivorship. Key Words : Littoraria scabra,  significance, ecology, survival, and mangrove ABSTRAKPenelitian ini menemukan bahwa signifikansi ekologi Littoraria scabra untuk survival di mikrohabitat mangrove Tombariri yang ekstrim adalah sebagai berikut berfungsi sebagai tempat istirahat, menghindari perendaman air, mencari makanan, meletakkan larva, menghindar cahaya dan bersembunyi dari predator-predator. Signifikansi L. scabra  distribusi spasial mengelompok untuk mereduksi stres kekeringan, suhu, terlepas di substrat akibat gelombang, aktivitas makan, reproduksi, kecocokan habitat. Signifikansi distibusi mengelompok dengan populasi tinggi untuk mengimbangi kuatnya predasi serta merespons tekanan seleksi alam yang kuat demi kelangsungan hidupnya. Kata Kunci : Littoraria scabra, signifikansi, ekologi, survival dan mangrove


2020 ◽  
Vol 8 (12) ◽  
pp. 1024
Author(s):  
Masaki Nimura ◽  
Shuzo Nishida ◽  
Koji Kawasaki ◽  
Tomokazu Murakami ◽  
Shinya Shimokawa

Global warming is feared to cause sea-level rise and intensification of typhoons, and these changes will lead to an increase in storm surge levels. For that reason, it is essential to predict the inundation areas for the maximum potential typhoon and evaluate the disaster mitigation effect of seawalls. In this study, we analyzed storm surge inundation of the inner part of Ise Bay (coast of Aichi and Mie Prefecture, Japan) due to the maximum potential typhoon in the future climate with global warming. In the analysis, a high-resolution topographical model was constructed considering buildings’ shape and arrangement and investigated the inundation process inside the seawall in detail. The results showed that buildings strongly influence the storm surge inundation process inside the seawall, and a high-velocity current is generated in some areas. It is also found that closing the seawall door delays the inundation inside the seawall, but the evacuation after inundation is more difficult under the seawall doors closed condition than opened condition when the high tide level exceeds the seawall.


1972 ◽  
Vol 62 (1) ◽  
pp. 113-127 ◽  
Author(s):  
J. R. Linley ◽  
G. M. Adams

The distribution of the larvae and pupae of Culicoides melleus (Coq.) in a natural beach habitat in an inlet on the Florida coast was studied in relation to tidal level and time of day. Larvae and pupae were confined to the intertidal zone and these distributions were unaffected by time of day or tidal level. Distributions of younger larval instars were displaced towards the inferred area of oviposition at higher elevations on the beach. Pupae were associated with the zone at and somewhat below high tide level. Differences in the vertical distribution of larvae between 0 and 2 in. deep between dark (pre-dawn)/low tide, morning/low tide and afternoon/low tide conditions were probably associated with larval response to light and heat.In laboratory experiments with a temperature gradient, second- to fourth-instar larvae preferred the 18–25°C range, but the fourth instars were the least discriminating. Laboratory experiments with a simulated beach showed that pupae flooded on an incoming tide remained in their burrows and immediately buried themselves more deeply when waves were generated in the water; they were able to return to the surface if buried, and survived drowning for four days. Inundated areas were avoided as pupation sites. The orientation of pupae at the sand surface and their formation in burrows was related to negative phototactic responses of the pupating larvae.


2014 ◽  
Vol 94 (7) ◽  
pp. 1367-1376 ◽  
Author(s):  
Marta Ronowicz ◽  
Piotr Kukliński ◽  
Kate Lock ◽  
Philip B. Newman ◽  
Mark Burton ◽  
...  

Submerged artificial surface imitates newly available habitat for settlement of marine fauna. It also enables study of the timing of benthic larval settlement. Such knowledge is important if the model of possible recovery after disturbance in protected areas is to be assessed. During this study recruitment of sessile benthic invertebrate fauna at spatial and temporal scales was investigated using artificial panels submerged in the Skomer Marine Nature Reserve (Wales, UK). Panels were exchanged monthly between May 2009 and September 2011 (with the exclusion of winter time). Recruitment was highly variable with regard to time and distribution; abundance and number of recruiting species varied significantly between sites (about 2 km apart from each other), depths (6 and 12 m), position on panels (top or underside) and years without any obvious trends. The highest number of individuals and highest values of species richness were at Bernies Rocks, at the greater depth and on the underside surface of panels. Bryozoans were the dominant taxon on panels in each studied year and month. Most macrofaunal species noted on panels exhibit a colonial life strategy with short-lived, non-feeding larval stage. Although many species settle all year round, levels of settlement usually peak in summer months, showing a seasonal recruitment pattern (Bugula fulva, Spirobranchus triqueter, Chorizopora brongniartiandEscharoides coccinea). Some species had a pronounced settlement peak in spring (e.g.Electra pilosaandBalanus crenatus).


2019 ◽  
Vol 44 (1) ◽  
pp. 27-35
Author(s):  
Tia Nuraya ◽  
Alan Frendy Koropitan ◽  
A'an Johan Wahyudi

We investigate variation in sediment carbon stock at Mempawah and Bakau Besar in West Kalimantan by analyzing organic carbon content from sediment samples taken within 20 cm depth. Our results show that organic carbon stock of sediments in Bakau Besar is generally higher than in Mempawah that may be due to riverine input of organic carbon into the mangrove forests. The riverine input of organic carbon is influenced tides, in which we find that organic carbon loads are higher during high tide compared to low tide. In particular, we find high organic carbon contents at a station in Mempawah (Station 3; 6.46 ± 0.23 tons C/ha) and another station in Bakau Besar (Station 2; 14.93 ± 1.43 tons C/ha). These two stations have mangrove density of 13,519 individuals/ha and 9,928 individuals/ha, respectively. We conclude that high organic carbon is influenced by riverine input as well as a high density of mangrove and the dominant type of mangrove vegetation at the sites.


Author(s):  
Sumera Farooq ◽  
Nazia Arshad

Sediment characteristics plays important role in the determination and functioning of coastal ecosystems. The present study is an attempt to evaluate the variability in sediment characteristics of the three beaches: Clifton, Sandspit and Buleji, at the Karachi coast. The samples were collected during pre-monsoon and south-west monsoon seasons to evaluate the seasonal differences. The sediments of the three sites showed variations in moisture content, organic matter and grain size. The highest mean moisture (27.17%) and organic contents (3.5 %) were recorded from the sediments of Clifton. The maximum fraction of sediments (> 80 %) consist of fine to very fine sand at all studied sites. The sediments of Clifton were high in very fine sand fraction and low in coarse sand fraction as compared to Sandspit and Buleji. The sediments of all the three studied sites are moderately sorted, negatively coarse-skewed and showed leptokurtic distribution. The studied beaches of Clifton, Sandspit and Buleji shows dissimilarity in sediment characteristics as indicated through Cluster and PCA analysis. The monsoonal influence on sediment characteristics was also observed at all the three studied beaches. The strong wave action during SW monsoon season results in the deposition of the coarser sediments at the high tide level thus increasing the steepness of the beaches.


2019 ◽  
Vol 20 (1) ◽  
pp. 197 ◽  
Author(s):  
Valentin Foulon ◽  
Pierre Boudry ◽  
Sébastien Artigaud ◽  
Fabienne Guérard ◽  
Claire Hellio

Following their planktonic phase, the larvae of benthic marine organisms must locate a suitable habitat to settle and metamorphose. For oysters, larval adhesion occurs at the pediveliger stage with the secretion of a proteinaceous bioadhesive produced by the foot, a specialized and ephemeral organ. Oyster bioadhesive is highly resistant to proteomic extraction and is only produced in very low quantities, which explains why it has been very little examined in larvae to date. In silico analysis of nucleic acid databases could help to identify genes of interest implicated in settlement. In this work, the publicly available transcriptome of Pacific oyster Crassostrea gigas over its developmental stages was mined to select genes highly expressed at the pediveliger stage. Our analysis revealed 59 sequences potentially implicated in adhesion of C. gigas larvae. Some related proteins contain conserved domains already described in other bioadhesives. We propose a hypothetic composition of C. gigas bioadhesive in which the protein constituent is probably composed of collagen and the von Willebrand Factor domain could play a role in adhesive cohesion. Genes coding for enzymes implicated in DOPA chemistry were also detected, indicating that this modification is also potentially present in the adhesive of pediveliger larvae.


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