Intertidal Region Research Articles

Tolerance to aerial exposure influences distributional patterns in multi-species intertidal seagrass meadows

Multi-specific seagrass meadow assemblages dominate most tropical intertidal regions but the relative role of environmental stress in determining distribution patterns is still uncertain. Here we combine observational and experimental approaches to examine aerial exposure as a factor driving species occurrence patterns in intertidal meadows of the Andaman archipelago, where up to 6 seagrass species co-occur. In the studied meadow, patterns of exposure did not map onto distance from the coast, instead creating a patchy matrix of exposure, based on fine-scale bathymetric differences. Distributional surveys showed that seagrass species were similarly patchy, often tracking the degree of aerial exposure during low tide. While some species (Halophila ovalis, Halophila minor, and Thalassia hemprichii) frequently occurred in submerged or subtidal areas and were rarely found in completely exposed areas, other species (Cymodocea rotundata, Halophila beccarii, and Halodule uninervis) also occupied areas that were subject to partial or complete aerial exposure during low tide. To confirm this pattern, we used field-based transplant experiments, employing a natural gradient of tidal exposure to subject six seagrass species to different desiccation exposure times. After a month, H. beccarii and H. uninervis transplants survived in areas that sustained more than 3 h of aerial tidal exposure without significant mortality, compared with other species (H. ovalis, H. minor, T. hemprichii, C. rotundata) that showed dramatic shoot mortality at the same exposure regimes. For all species, 4 h represented the upper limit of exposure, in both experimental and distributional studies. However, despite their wider tolerance of exposure to air, H. beccarii and H. uninervis did not dominate the entire meadow. This could be a result either of their poor tolerance to other environmental factors or their lower competitive abilities among other mechanisms. This suggests that in tropical multi-specific meadows, strong environmental filters could override clear intertidal zonation to create patchy matrices based on species tolerances.

Skeletal anatomy of the pectoral fin in mudskipper species from terrestrial and aquatic habitats.

Mudskippers are a group of amphibious fishes in the family Oxudercidae, whose species inhabit a range of habitats from mostly aquatic to mostly terrestrial. Most of our understanding about habitat preference comes from natural history observations, particularly where they are collected (i.e., low intertidal vs. high intertidal regions). Mudskippers have undergone several morphological changes to accommodate a terrestrial life, including major changes to the pectoral and pelvic girdles. These changes result in a novel crutching gait, which mudskippers use to move over land. Though the appendicular morphology and crutching gait of mudskippers have been described in some species, few studies have compared skeletal structures across the family. In our study, we use microcomputed tomography (µCT) scans to compare the skeletal anatomy of 16 species of aquatic and terrestrial mudskippers. Linear discriminant analysis is used to analyze measurements obtained through geometric morphometrics (landmarks). We found bone structures of the pectoral region in the terrestrial group were significantly longer and wider than those in the aquatic group. Furthermore, a significant difference in anatomy is shown between terrestrial and aquatic genera with both axial and appendicular elements contributing to the separation between groups. This work describes the differences in skeletal morphology associated with terrestriality in mudskippers and provides valuable insights into specific anatomical characteristics contributing to their adaptation to novel environments.

Screening of Anti-inflammatory and Analgesic Activities of Caulerpa Racemosa from the Bay of Bengal, Bangladesh

Caulerpa spp; is a remarkably potential seaweed due to its pharmacological importance, high nutritional compositions, biological activities , and human health benefit. It is a species of ulvophyte green algae inhabiting mostly in the intertidal and shallow sub-tidal coastal regions in the Asia- Pacific and commonly consumed in South-East Asia for its high contents of vitamins and minerals. Besides its culinary uses, it is well-reported for its antibacterial, antifungal, diabetes, blood pressure, and lipid-lowering properties. However, to date, no extensive assessment of the diversity, distribution, and biological activity assay of these seaweeds found on the Bangladesh coast has been carried out. This study aimed at anti-inflammatory and analgesic studies of 50% ethanolic extract of Caulerpa racemosa. collected from St. Martin's Island, Bangladesh. Consequently, secondary metabolites such as steroids, flavonoids, glycoside, and saponin were also detected in the phytochemical assay. In the present study, 25 & 50mg/kg body weight of ethanolic extract of C. racemosa was used in hot plate, acetic acid, formic acid, and carrageenan-induced paw edema in Swiss albino mice showing C. racemosa extract has significant analgesic and anti-inflammatory properties.
 Bioresearch Commu. 9(2): 1330-1339, 2023 (July)

Population structure and reproductive biology of Clibanarius rhabdodactylus Forest, 1953 (Crustacea: Anomura: Diogenidae) in Gujarat state, India

The population structure of a hermit crab, Clibanarius rhabdodactylus Forest, 1953 (Diogenidae), was studied in the rocky intertidal region of Veraval, located on the Saurashtra coast, Gujarat state, India. Monthly sampling was carried out from March 2021 to February 2022 during low tide time using the handpicking technique, while the catch per unit effort method was employed by one person during the period of 4 h in an area of 500 m2. The collected individuals were classified as male, non-ovigerous female, and ovigerous female. Size (mm) and weight (g), egg size, number, and egg mass weight were recorded and fecundity was calculated. A clear sexual dimorphism was observed, with males being significantly larger than females. The overall sex ratio was female biased. The overall size frequency distribution showed bimodal distribution in male while unimodal in females. Ovigerous females occurred throughout the year with peaks in January to June and September to October, showing a continuous reproductive pattern of the species. The total number of eggs, size of eggs, and total weight of egg mass showed a positive correlation with the shield length and body weight of the ovigerous females.

Survive the north: transplantation for conservation of mangrove forests requires consideration of influences of low temperature, mating system and their joint effects on effective size of the reforested populations

Mangrove forests, which occur in the intertidal regions of tropical and sub-tropical zones, have high ecological and economic values. They have rapidly reduced over the past decades due to various reasons. Reforestation is a common strategy for the conservation of mangroves, but information on the renewal capacity and viability of these artificial mangrove populations is still lacking. Here, we estimated the effective population size (NE) of an artificial population of Kandelia obovata (Rhizophoraceae) and explored the effects of intrinsic and extrinsic factors on changes in NE to evaluate population viability and develop appropriate management strategies for mangrove forests. This population consisted of three ecologically and genetically differentiated groups that had experienced a major low-temperature event during the winter of 2015–2016 and varied in cold resistance. We first detected population bottlenecks and estimated contemporary values of NE for different groups using microsatellite data. Next, we performed paternity analyses for seedlings and propagules to explore variations in the reproductive success of individuals within the three groups before and after the low-temperature event. Lastly, we simulated four scenarios to characterize the effects of low temperature, mating system, and variance in reproductive success on changes in NE in a hypothetical metapopulation based on empirical estimates. Our results show that groups with moderate or poor cold resistance experienced local bottlenecks, and shifts in effective breeders occurred following the low-temperature event, which indicates that low temperature has an effect on not only population size but also reproductive success. Furthermore, our simulations revealed that changes in NE are jointly affected by reproductive success, mating system, and environmental conditions. These findings enhance our understanding of the multiple factors that affect NE, and provide key information that will aid the reforestation and management of mangrove forests, especially when they are introduced to high-latitude areas.

The First Record of <i>Ophioteichus multispinum</i> (Echinodermata: Ophiuroidea) from Japan, with Notes on Its Ossicle Description and Ecology

Three specimens of Ophioteichus multispinum H. L. Clark, 1938 are redescribed from approximately 2.3–12.6 m water depth at Sabiura, Kushimoto, Wakayama Prefecture in central Japan. The species occurs completely buried on sandy bottoms. Ossicle morphology is described. Based strictly on images, we present in situ occurrence of the genus Ophioteichus H. L. Clark, 1938 from the intertidal regions of Susami, Wakayama Prefecture, and Tosashimizu, Kochi Prefecture.

Individually unique, fixed stripe configurations of Octopus chierchiae allow for photoidentification in long-term studies.

The Lesser Pacific Striped Octopus, Octopus chierchiae, is a small iteroparous octopus known to inhabit intertidal regions of the Pacific coast of Central America. Many details about its life history and ecology remain unknown. For apparently rare and delicate animals such as O. chierchiae, non-extractive sampling methods are necessary to study individuals and populations over time. After photographically documenting the physical development of 25 octopuses from hatching, we have concluded that O. chierchiae has individually unique stripe configurations that remain constant throughout their post-hatchling lifetimes. Furthermore, using photographs taken of animals in captivity on different dates over many months, we show that untrained volunteers can accurately identify whether or not a pair of images depicts the same individual octopus. These results demonstrate that laboratory-reared individuals could be identified via photographs taken at different points in their lifetimes, which suggests wild individuals can also be recognized and observed for longitudinal field studies. In addition, our results imply potential for photoidentification and community science to be used as non-extractive, non-intrusive sampling methods for future studies of wild O. chierchiae.

Sharing is living: The role of habitat heterogeneity in the coexistence of closely related species.

In biologically diverse ecosystems, an essential process to support competing species to coexist is ecological differentiation. Habitat heterogeneity is, hence, important in establishing species abundance and richness, favoring the coexistence of species due to habitat partition. In this context, shading and species thermal tolerance can be good factors to elucidate the role of habitat heterogeneity in the habitat partition among closely related species. Herein, we study shading effects in microhabitat selection, behavior, and physiological limitation on two species of fiddler crabs (Leptuca leptodactyla and Leptuca uruguayensis). Indeed, shading conditions influenced fiddler crabs species proportion over time, with L.leptodactyla more associated with nonshaded/warmer areas while the L.uruguayensis to shaded/cooler ones. They also adjusted their behavior differently from each other to deal with thermal stress. Finally, we have demonstrated that these effects are related to species' physiological limitations. We conclude that biologically diverse ecosystems, such as intertidal regions from estuaries (e.g., mudflats and mangroves), support the coexistence between closely related species by reducing competition due to habitat partition.

Intertidal Green Crab Survey Over a Ten-Year Period on a Maine Cobble Beach

Here we report on the long-term monitoring of Carcinus maenas (European Green Crab) populations on an intertidal region of a cobble beach in Maine conducted from 2011 to 2021. The number of Green Crabs collected fluctuated between 129 and 474 individuals per sample event. We collected crabs twice each year, with a total number collected of 389 to 798 per year. In addition, we collected Hemigrapsus sanguineus (Asian Shore Crab) in 2 sample years (2019 and 2021), accounting for only 7 individuals. No compelling relationships between Green Crab densities and sea-water temperature, average carapace width, or year of the collection were revealed.

Morphological variations in blood cockle Tegillarca granosa (L, 1758) populations collected from the south-east and south-west coasts of Bangladesh

Morphology helps in studying the external features of an individual, including the size, shape, structure of the animals and in determining the evolutionary relationships among organisms. Current study was undertaken to investigate the morphological variations between the two populations of blood cockle, Tegillarca granosa collected from the south-east (west coast of Maheshkhali Island, Cox’s Bazar; S1) and south-west (Jamuna River Estuary near Ishawrypur, Shemnagar, Shatkhira; S2) coasts of Bangladesh. Samples were drawn from the intertidal region during low-tide by hand-picking with the aid of local people in March 2020 from both sites. Fifteen primary parameters, and 27 secondary parameters obtained from the ratios of different primary parameters were studied to compare the values between the two populations. Out of 15 primary morphological parameters, there was no significant difference (p>0.05) between the populations. Among the 27 secondary morphological parameters, only 4 parameters were significantly different (p<0.05) between the two populations. The statistically different parameters were shell length (SL)/wet tissue weight (TWW), shell height (SH)/wet tissue weight (TWW), shell thickness (ST)/wet tissue weight (TWW) and condition index (CI). The ratios of shell dimensions and wet tissue weight were significantly higher (p<0.05) in S2 when compared with S1 indicated that S1 population could be more economically viable due to their relatively higher edible meat content. The CIs were significantly higher (p<0.05) in S1 population than the CIs of S2 population. The values of CIs reflected that S1 population had better health condition than S2 population. The ratios of different shell measurements did not vary significantly implied that both populations were homogenous in size, shape and structure. Morphological analyses of different populations of T. granosa revealed that habitat could play a vital role in morphological variations.

Unveiling the hidden treasures: the vital contributions of Bhitarkanika mangrove in supporting local communities

Mangroves are salt-resistant vegetation that inhibit the muddy intertidal region of tropical and sub-tropical countries. Bhitarkanika Mangrove Sanctuary is one of the hotspots of Odisha state due to its wide range of biodiversity. Mangroves are always integral to the coastal livelihood by providing goods and services to the communities. The importance of mangroves gets neglected by sideling its provision of valuable resources and protection services against cyclones and storms. The present article studied the benefits provided by the Bhitarkanika Mangroves forests to the local communities and focuses on the sustainable conservation of resources for the future. Evidence-based suggestions are suitable for achieving the sustainability of local communities by adopting conservation measures.

Ichthyofaunal Diversity of Sikka Coast, Gulf of Kachchh, Gujarat

The vast intertidal region on the Sikka coast harbours various fertile ecosystems like mangroves, coral reefs, seaweed and sea grasses which support various biota including fishes. The present study aimed to document the marine ichthyofaunal diversity along the Sikka coast located on the northern coast in the Gulf of Kachchh, Gujarat. During the present study, a total of 102 fish species belonging to 2 classes, 22 orders, 53 families, and 72 genera were recorded from November 2021 to April 2021. Eupercaria was found to be the dominant order (21.56%, 22 species) followed by Clupeiformes (11.76%, 12 species), and Carangiformes (10.78%, 11 species). The highest number of species were recorded from the family Carangidae followed by Mugilidae and Sparidae. Out of 102 species, 97 species were either Least Concern or Data Deficient in the IUCN Red List Status, 3 species were VU (Vulnerable) and 2 species were NT (Near Threatened). Among the recorded fish species, 64% of fish species were carnivores while 21% of fishes were herbivores or planktivores while the rest of the species were omnivores.

Evaluation and characterization of biochar on the biogeochemical behavior of polycyclic aromatic hydrocarbons in mangrove wetlands

As the inter-tidal regions between land and ocean, mangrove ecosystems have high polycyclic aromatic hydrocarbons (PAHs) content, and the over accumulation of PAHs in mangrove wetland poses a serious ecological risk to the health of plant and living creatures. Comparison to the agricultural sources -biochar, biochar produced from wetland plant has lower O/C (molar ratio), larger N contents, higher stability and more benefits. However, whether the rhizosphere action occurs in biochar- amended sediment and how to influence the biogeochemical behavior of PAH have rarely been reported. In this context, a leaching procedure and pot experiment (60-d) were performed on migration and transformation of PAH at the sediment, and toxicity and their bioavailability in plant affected by the presence of Kandelia obovate-derived biochar in Southeast China. Root exudates amendments significantly increased the cumulative leaching-loss of pyrene by 36–51 % with or without biochar amendment via continuous diffusion and partition process, and biochar amendments decreased the bioavailability of pyrene (16.8–25.8 %) probably due to a faster pyrene sorption on inter-phase transport against desorption. The regression analysis indicated a significant relationship (p < 0.05) between leachate pH and pyrene concentrations. Notably, the bioaccumulation of pyrene on K. obovate parts had significant negative correlation (p < 0.05) to biochar. The activities of four key antioxidizes (phenylalanine ammonia-lyase, dismutases, peroxidases and catalases) were significantly decreased with the application of biochar. Moreover, biochar plays a positive role in cytochrome C release and phosphatidylserine secretion, and a combined biochar-rhizosphere approach can improve the stress tolerance and resistance of K. obovate with an enhanced synergetic effect, which could be a feasible remediation strategy for alleviating the mangrove sediment contaminated by PAH.

Egg production by the exotic shrimp Athanas dimorphus (Caridea: Alpheidae) in a harbor area in northeastern Brazil

The shrimp Athanas dimorphus was recently recorded in the Western Atlantic, with successive records of introduction along the Brazilian coast. The present study aimed to investigate aspects related to propagule pressure of this shrimp, such as egg production, fecundity, egg volume, and the correlation between fecundity and female size. Additionally, we aimed to determine whether the species is established in the locality, in addition to inferring its ability as a propagule donor to adjacent regions. The following hypotheses were formulated: (1) the species has a reproductively active population in the studied area; (2) the studied population shows continuous reproduction throughout the year. Ovigerous females were collected monthly in the intertidal region of Praia do Paraíso, State of Pernambuco, northeastern Brazil, between April 2017 and March 2018. A total of 524 ovigerous females were sampled. Of these, 362 females carried normal eggs – 324 with eggs in stage I of embryonic development, 5 in stage II, 33 in stage III – 161 had abnormal eggs, and 1 carried eggs in the hatching stage. Only females carrying normal eggs were used in the analyses. The females’ carapace length and egg number and volume were measured and correlated. Mean fecundity in stage I was 63.2 ± 39.1, with egg number decreasing significantly between stages I and III. The mean egg volume increased significantly between stages I and III, presenting a total increase of 35%. The fecundity and size of females were positively correlated. Our results meet the two formulated hypotheses, indicating that A. dimorphus has a reproductively active population in the study area, with continuous reproduction throughout the year. As predicted by the propagule pressure theory, species with such characteristics are considered to be effective invaders, increasing their chances of reaching and establishing in new areas.

Reproductive cycles of the oviparous sponges Cinachyrella apion (Spirophorida) and Tethya maza (Tethyida) in a tropical intertidal environment

AbstractEnvironmental factors are constantly changing in the intertidal region. Consequently, the various benthic organisms that densely colonize this ocean area had to adapt to these constant changes. Reproductive strategy might be considered one of these adaptations. However, knowledge about this aspect of the biology of marine invertebrates is still contentious for some groups, especially with regard to sponges (Porifera). Here, we investigated the effects of different environmental factors on the timing and effort of sexual and asexual reproduction in Cinachyrella apion and Tethya maza, two oviparous demosponges in Salvador, Bahia, Brazil. We analyzed the influence of humidity, atmospheric temperature, seawater temperature, photoperiod, rainfall, height of low tides, and chlorophyll‐a concentration on the density and size of oocytes and buds of these sponges. Both species reproduced aperiodically. Cinachyrella apion had a maximum 2.8 ± 4.04 oocytes/mm2 and 0.73 ± 0.15 buds/mm2, whereas T. maza had a maximum 6.0 ± 12.21 oocytes/mm2 and 0.31 ± 0.13 buds/mm2. The density of oocytes in C. apion was positively influenced by chlorophyll‐a concentration, whereas that of T. maza was negatively modulated by relative humidity. We did not observe any relationship between the environmental factors and bud density in C. apion, but bud density variation in T. maza was positively related to chlorophyll‐a concentration and to seawater temperature. It seems that individuals of both species alternated between the production of sexual and asexual propagules, suggesting a trade‐off between reproductive modes. Therefore, asexual and sexual reproduction seems to impact population growth and reproduction of both species, likely contributing to the recruitment of new sponges. In tropical intertidal regions, multiple environmental factors seem to contribute more to determining the quantity of sexual and asexual reproductive elements rather than the species' reproductive period.

MARINE ALGAE DIVERSITY AT COASTAL AREA OF VERAVAL, GUJARAT

The Veraval coast situated at (20º54’30º N 76º21’20º E) the gulf of Kachchh, western coast of Gujarat, India. This site has a rich diversity of marine algae, corals and gastropods at intertidal region. The main aim of present study focused on occurrence and diversity of marine algae at coastal site. The study carried out in month of December- 2019. Algae collection was done during low tide situation, at this condition algae were collected with their holdfast/rhizoid. Total 33 species of algae were collected from three different phylum. Among these maximum 18 species were recorded from red algae, 8 species were recorded from green algae and 7 species were recorded from brown algae.

Evaluation of benthic quality status and ecosystem functioning of soft bottom macrobenthos in the intertidal region with reference to Gulf of Khambhat, India

The Gulf of Khambhat is a dynamic intertidal regime influenced by variety of factors such as multiple water runoff from different rivers, wastewater input from industries and urban areas and natural phenomenon like tidal influence. Hence, it is necessary to evaluate the quality status of the intertidal areas along the gulf of Khambhat. Present study is a baseline study for the monitoring of ecosystem health of macrobenthos along the gulf of Khambhat coast. Macrobenthos are known as indicators for the organic enrichment, hence macrobenthos were used to assess the benthic quality status. BIOENV identified sediment quality parameters as most influential parameters and segregated the locations as sandy and sandy muddy habitat. Two robustly use biotic indices AMBI and BOPA were used to assess the ecological quality status of macrobenthos. From the biotic indices Alang was identified as most polluted location where as Diu as pristine habitat. Biological trait analysis (BTA) and Functional diversity indices (FD) explained the functioning of ecosystem along the Gulf of Khambhat where habitat heterogeneity was playing a major role in the species as well as functional diversity. Though biotic indices were showing positive results with functional diversity, no significant relationship was recorded.

Mangrove forest conservation vs shrimp production: Uncovering a sustainable co-management model and policy solution for mangrove greenbelt development in coastal Bangladesh.

Mangrove forests are remarkably diverse and productive ecosystems, with distinctive biophysical environments in intertidal coastal regions of the tropics and subtropics. In these regions, shrimp cultivation is identified as a profitable business and one of the main reasons for clearing of mangroves to construct shrimp farms. Against this backdrop and based on the first author's previous PhD research and other relevant scholarly works, in this commentary we discuss the aspects and contexts of the mangrove-based integrated shrimp farming system. Then, we recommend a model of co-management and a set of policy option towards sustainable silvo-aquaculture to protect/restore the mangrove forests and sustain shrimp production in coastal areas of Bangladesh. Mangroves and shrimp culture are not necessarily incompatible. Many mangrove species have been identified as beneficial for shrimp culture for a number of possible reasons. Most importantly, the nutrients in the leaf litter of several mangrove species have been found to enhance natural food production for shrimp. Besides the nutrient input, the leaf litter also provides surface area for biofilm development, on which different life stages of shrimp can graze. In addition, the combination of mangrove leaf litter and feed has been shown to enhance shrimp production synergistically. Additional economic benefits from mangrove-shrimp co-management include the production of timber (e.g. buildings, boats and fuel woods) and non-timber products (e.g. fruits, honey, fibers, firewood, resins and bark). Thus, mangrove-based aquaculture or silvo-aquaculture system can be considered as a nature-based solution to sustainably revitalize the economy in coastal areas where shrimp has been the economic mainstay. Though there are positive effects, we point out some potential negative impacts of mangrove-based shrimp culture, like the anti-nutrients content in the leaf litter, which might impact shrimp production. In addition, the long term use of mangrove leaf litter might degrade the water quality. Therefore, the co-management policy recommends a controlled practice of mangroves in shrimp culture to balance conservation of mangrove-based ecology and profitable shrimp production. The approach promotes nature-based solutions and fosters sustainable pathways for food production, considering socio-economic and environmental dynamics.

A new species of genus Rhabdophrya (Ciliophora: Suctorea) from the west coast of India and comments on the genus taxonomy

The article presents the description of a new species of the suctorian genus Rhabdophrya inhabiting the body surface (cuticle) of harpacticoid copepod from Navy-Nagar, Mumbai intertidal coralline region, west coast of India, the Arabian Sea. The diagnosis of the genus is refined, all other species diagnoses and identification keys are presented.

Effect of some environmental factors on the occurrence and distribution of Polychaeta Namalycastis indica (Southern, 1921) in the intertidal region of Shatt Al-Arab River Basrah Iraq

The current study was conducted on N. indica in three stations for the period from December 2017 to November 2018 (Al-Sharsh, Al-Salhiya and Al-Dweab), as samples were collected monthly. Some environmental factors were calculated, such as water temperature. The lowest water temperature was 12 °C during January and the highest temperature was 33 °C during July, both in Al-Salhiya station. The lowest value of salinity was 0.5‰ reached in April and November in Al-Sharsh station, while reached highest value ‰ 39.3 were recorded during July for Al-Dweab station, the light transmittance values ranged between (63-18) cm, recorded during July and November for Al-Salhiya and Al-Sharsh stations, respectively. As for the values of dissolved oxygen, it ranged between (12.1-5.1) mg/liter during August and May in the two stations. Al- Salhiya and Al-Sharsh, respectively. As for the bottom sediments of all the stations, they were alluvial with few and different percentages of sand and clay. The study showed that the studied environmental factors have an impact on the distribution and spread of this species within the horizontal and vertical sections in the tidal zone. The total density and density were measured within the horizontal distribution pattern in each station and the monthly total density ranges were 592-32 individuals/m2. The density of the three species was calculated within the horizontal distribution after dividing the area into three sections for each station. The results of the study indicated that there were significant differences at the level of P&lt;0.05 for densities between the first and second different sections of N. indica, and there were significant differences between the first and third sections and between the second and third sections.