Intertidal Region Research Articles

Characterizing the habitat function of bivalve aquaculture using underwater video

Bivalve aquaculture is an expanding coastal industry with the potential to modify the habitat of fish and crab species, affecting their refuge, movement, and feeding. The habitat function of shellfish aquaculture is not yet well understood, in part due to difficulties in data collection using traditional methods. Underwater video was used to observe fish and crab species’ affiliations with cultured Pacific oyster Crassostrea gigas and Manila clam Venerupis philippinarum aquaculture sites in comparison to uncultured reference sediment and eelgrass habitats. Sites were monitored in 9 locations across 3 regions of Puget Sound, Washington, USA, in the summers of 2017 and 2018. Of the 3038 fish and crabs observed, 98% were represented by Embiotocidae (surfperch), crabs, three-spined stickleback Gasterosteus aculeatus, Cottidae (sculpins), and Pleuronectiformes (flatfish). Overall, the affiliations of fish and crabs with bivalve aquaculture varied by species groups, culture type, and regional environmental and habitat conditions. These interactions varied on a scale of approximately 150 km, highlighting variation of aquaculture-ecological interactions at a scale not previously recorded in Puget Sound. Species composition varied between aquaculture and non-aquaculture habitats in 2 of the 3 regions studied. Species diversity and richness in aquaculture habitats varied regionally, relative to reference habitats. Pelagic species were more abundant in aquaculture and reference sites that had vertical structure, but abundances of demersal and benthic species on aquaculture habitat relative to reference sites varied regionally. The availability of habitats within intertidal regions, including varying types of aquaculture, could determine community structure for marine organisms such as fish and crab.

First Record of the Invasive Mussel Mytella strigata (Mollusca: Bivalvia: Mytilidae) in Panguil Bay, Southern Philippines

Here, we report the first record of the invasive mussel species Mytella strigata Hanley, 1843 in Panguil Bay, southern Philippines confirmed through its conchological features. Mussels appeared in dense mats attached to rocks, wood, and substrate in the intertidal region in the innermost portion of the bay. Locals first noticed the species in late 2018, which, according to them, adversely affected their catches of mangrove crabs Scylla spp. and the Asian hard clam Meretrix meretrix Linnaeus, 1758. There is a need to ascertain the distribution of the species within the bay, investigate socio-ecological and economic impacts, and formulate monitoring, surveillance, and impact mitigation measures.

The effects of wind‐generated currents on velocity asymmetry in tidal basins with varying geometries

AbstractGeomorphologic characteristics of tidal basins have been shown to control tidal asymmetry and associated sediment transport potential in coastal regions. In this study, we examine how winds modulate horizontal velocity asymmetry patterns in shallow tidal basins. Numerical modelling experiments for a series of idealized basins in which planform shape and bathymetry were varied, reveal that an increase in wind speed promotes more extreme horizontal velocity asymmetry (larger velocity asymmetry values) without substantially altering the overall spatial pattern of velocity asymmetry throughout the domains. The wind forcing primarily influences mean and peak flow velocities, with a limited effect on tidal harmonics. Changes to the velocity asymmetry patterns are most evident for wind speeds of 6 m/s and greater, and for wind directions parallel to the main axes of the basins’ tidal channels. However, the velocity asymmetry is strongly depth‐dependent. Shallow intertidal basin regions are characterized by a downwind‐directed increase in velocity asymmetry, whereas deeper subtidal channels display asymmetry changes in the opposite direction. Additionally, the timing and duration of a wind event are found to influence the velocity asymmetry patterns. Wind events coinciding with flooding tides result in the most noteworthy differences between the relative size of the peak flood‐ and ebb‐directed currents inside the shallow basins, for wind event durations of both 3 and 6 h.

Hidden taxonomic characters in otoliths of blenniid fishes (Teleostei: Blenniidae) from the Iranian coasts of the Persian Gulf and Oman Sea ecoregions: A scanning electron microscopy approach

AbstractIn the present work, the morphological characteristics of sagitta were described and analysed for 10 species of combtooth blennies (Blenniidae) inhabiting the intertidal region of the Persian Gulf and Makran zone of Oman Sea to see the taxonomic usefulness of otoliths, especially their hidden characters for species identification. Based on the obtained results, sagitta morphology could be considered as diagnostic characters distinguishing the genera Alticus, Antennablennius, Istiblennius, Omobranchus and Parablennius showing differences related to general shape, that is, elliptic/oval to triangular; shape of antirostrum and its degree of development; the degrees of convexity of ventral and dorsal margins, and shape of ostium. The common/general otolith characters shared in the all studied combtooth blennies, is the heterosulcoid condition, which is a shared character with Perciformes and Gobiiformes. The type of sulcus is ostial, and it can be considered as a plesiomorph character shared with a basal group of actinopterygian fishes. The obtained results could be useful in taxonomical, paleontological, ecological and food and feeding habits studies.

Seaweeds of South Andaman: diversity, distribution, biochemical characterization and fatty acid profiling of some selected species

ABSTRACT The huge rise in seaweed-derived bioactive compounds demands immediate attention of under-explored seaweed species. The oceanic bio-resources in the tidal stretch of the Andaman Islands are relatively unknown. The present study explores seven intertidal regions of South Andaman Island to understand the species richness and existing seaweed biomass. Biochemical and fatty acid components were assessed for 15 seaweed species, commonly available in the study sites. A total of 67 species of seaweeds were collected during a one-year survey, most of which belonged to Chlorophyta, Rhodophyta and a few in Phaeophyta. The species richness was higher in sandy and coarse substrata, while highest species density was found on rocky shores. The P value for species richness at 5.05E-15 also validated the variation in seaweed distribution and diversity in the selected locations. The nutritional composition varied significantly among the species and was mostly characterized by higher levels of carbohydrate especially in Gracilaria spp. Carbohydrate content ranging from 3.52–48.22% accounted for most of the nutrient component. The overall protein ranged between 2.41–18.67%, whereas the total lipid varied from 2.16–11.90% and about 10% of total lipid content was available in most species. The significant outcome of this study was the detection of 6.34% EPA in Boergesenia forbesii and 2.40% of gamma linolenic acid in Acetabularia acetabulum which could be of significant importance in the food, bioenergy, pharmaceutical and cosmetic industries.

Human trampling decreases surface activity and disturbs behavioral rhythm of an endangered intertidal crab

Human recreational visits to tidal flats increase trampling pressure, which has a significant impact on the coastal benthic ecosystem. The fiddler crab Austruca lactea, which inhabits the upper intertidal region, is endangered in temperate regions such as Japan and South Korea. The vulnerability of their habitat to human activities along with their limited summer reproduction period may have contributed to the decrease in fiddler crab populations in these regions. We conducted experiments to elucidate the effects of trampling on the surface activities and courtship behaviors of A. lactea, which represent ecological indicators for tidal flat ecosystems. During the 46-day trampling period, we observed the number of active crabs on the surface of the tidal flat under three different trampling intensities (heavy trampling = 60 steps/m2; moderate trampling = 20 steps/m2; and no trampling). The density of individuals of both sexes active on the surface and that of courting males significantly decreased under both heavy and moderate trampling intensities. In addition, the feeding and courtship rhythms of male A. lactea collapsed under continuous trampling events. We monitored the site once per week, and surface activity did not recover fully until the sixth week after the trampling period. Our results demonstrated that trampling on the tidal flat disrupted the intensity and timing of crab surface behavior and male reproductive surface behavior, and thus may, ultimately, have an impact on the population dynamics of A. lactea.

A Comparison of the \u201cReduced Losses\u201d and \u201cIncreased Production\u201d Models for Mussel Bed Dynamics

Self-organised regular pattern formation is one of the foremost examples of the development of complexity in ecosystems. Despite the wide array of mechanistic models that have been proposed to understand pattern formation, there is limited general understanding of the feedback processes causing pattern formation in ecosystems, and how these affect ecosystem patterning and functioning. Here we propose a generalised model for pattern formation that integrates two types of within-patch feedback: amplification of growth and reduction of losses. Both of these mechanisms have been proposed as causing pattern formation in mussel beds in intertidal regions, where dense clusters of mussels form, separated by regions of bare sediment. We investigate how a relative change from one feedback to the other affects the stability of uniform steady states and the existence of spatial patterns. We conclude that there are important differences between the patterns generated by the two mechanisms, concerning both biomass distribution in the patterns and the resilience of the ecosystems to disturbances.

Impact of Intertidal Distribution on the Physiological Performance of the Filter-Feeder Bivalve Perumytilus purpuratus (Bivalvia, Mytilidae) from Southern Chile

Intertidal animals experience reduced feeding times and differentiated respiratory capacity associated with aerial exposure, the duration of which depends on their location within the intertidal zone. Perumytilus purpuratus is a sessile mussel that forms dense mats in the rocky mid-intertidal in southern Chile. For this species, we documented the impact of different times of aerial exposure (3 and 6 h) on rates of oxygen consumption and feeding, according to their vertical location (upper and lower limits) within the intertidal zone. Mean oxygen consumption rates in air for individuals located in the upper intertidal zone were 52% higher than those of individuals located at the lower limits of their intertidal distribution. Additionally, individuals from the lower intertidal region always presented higher rates of oxygen consumption and particle clearance rates (58% higher and 18% higher, respectively) during immersion compared to individuals collected from the upper limit of their intertidal distribution, regardless of the duration of previous aerial exposure. Although we found no significant habitat-related differences in the relationship between shell length and gill surface area, individuals sampled from the lower intertidal zone were 8% heavier in dry tissue weight than individuals with the same shell lengths collected from of the upper limit of their intertidal distribution. Our results suggest that the individuals of this species near the upper limits of their intertidal distribution can probably compensate (e.g., higher absorption rate) for the reduced time that they have available for clearance, which might help them to avoid a major energetic disadvantage.

A statistical assessment of plastic associated marine organisms found on intertidal plastic debris off the coasts of South Andaman Island of the Indian Archipelago

The purpose of this study is to relate the distribution and diversity of organisms found in association with plastic debris from South Andaman intertidal ecosystem using several statistical functions. In this study, ten different sites at South Andaman Island were examined for six months for plastic debris of various shape, size and colour along with the concerned organism. A total of 34 species of fauna and 17 species of flora are found associated with the plastic debris from this study. The most common ones are Arthropods, Bryozoans, Annelids and Rhodophyta. Few rare ones are sea anemones- Anthopleura handi and Actinia equina which were also seen attached on hard plastic objects. Diversity analysis highlighted the species evenness and diversity of Mazar Pahad to be maximum and species richness of Brookshabad to be the highest. No correlation was seen between the colour of plastic and the associated organism. Barnacle, Spirorbis and Sea Anemone prefer hard-rigid plastic fragments, whereas Bryozoans prefer a flexible, smooth surface. Lepas, on the other hand, preferred bottle caps, rubber material, and ropes. Many polychaetes were found in almost all the stations indicating that the coast and the water are quite polluted. Correlation between debris size and the number of taxa group showed stochastic phenomenon. Positive correlation was seen among the colony size of taxa group in relation with the exposed area of the debris. In terms of the distribution of plastic debris across the various zones of the intertidal region and the preference of the specific flora or fauna groups, no general trends or pattern was observed. Through this study, it is understood that plastic in one way provides shelter to certain organisms but at the same time harms other organisms through invasion as well as by providing an unnatural habitat.

Seasonal Controls on Sediment Delivery and Hydrodynamics in a Vegetated Tidally Influenced Interdistributary Island

AbstractRiver deltas are maintained by a continuous supply of terrestrial sediments that provide critical land building material to help sustain and protect vulnerable ecological communities and serve as natural storm protection barriers. Local hydrodynamics are important in determining the degree to which fluvial sediments are removed from the water column and retained on the delta complex. During 2014, we measured hydrodynamics and sediment transport characteristics at one of the world's most rapidly prograding deltas, the Wax Lake delta in Louisiana, USA. We observed waves to be the dominant source of bottom stress for 70% of our observations. Sediment concentration tended to increase with shear stress, but only after stresses exceeded 0.01–0.02 Pa. Significant wave height and bottom stress were substantially reduced after June, when the emergence of American lotus (Nelumbo lutea) formed a dense canopy over the intertidal regions of the island splay. Hydrodynamics during these summer vegetated conditions were much more favorable to floc formation, and by extension particle settling, as shown by trends in the Kolmogorov microscale parameter over the course of the measurement campaign. Together, these findings suggest that the timing between peak river discharge and the emergence of vegetation may have a strong influence on rates of progradation in seasonally vegetated delta splays, whereby sediments delivered by flood events that extend late into summer may be governed by hydrodynamics that favor particle deposition, whereas those delivered prior to the summer may be more prone to remain in suspension and bypass the delta complex.

A new species of Parathyone (Holothuroidea: Dendrochirotida: Cucumariidae) from northeastern Brazil, with a key to species.

A new species of Dendrochirotida sea cucumber, Parathyone itapuaensis, is described and illustrated herein based on specimens collected from rocky intertidal regions of the northeastern coast of Brazil. The new species is characterized by a suite of morphological characters revealed by light stereomicroscope, SEM and microCT studies of the calcareous ring, dermal ossicles, Polian vesicles and madreporite. Parathyone itapuaensis sp. nov. is characterized by having 10 tentacles, two Polian vesicles and single madreporite; length of anterior process (radial plate) larger than length of the base of the radial plate; body wall with buttons with triangular knobs and knobbed multiperforated plates in the anal region; and tentacles with arched rods, knobbed in the margins and shallow cups knobbed in the outer and inner surfaces. A key to the recognition of Parathyone species is given.

Molecular and morphological characterisation of the metacercariae of two species of Cardiocephaloides (Digenea: Strigeidae) infecting endemic South African klipfish (Perciformes: Clinidae).

South African clinids are a major component of the temperate intertidal regions that are also known to participate in life cycles and transmission of several groups of parasites. However, the knowledge of trematode diversity of these fishes is incomplete. In this study, two species of Clinus Cuvier, the super klipfish Clinus superciliosus (Linnaeus) and the bluntnose klipfish Clinus cottoides Valenciennes, were collected from six localities along the South African coast and examined for the presence of trematodes. Metacercariae of Cardiocephaloides Sudarikov, 1959 were found in the eye vitreous humour and brain of C. superciliosus and in the eye vitreous humour of C. cottoides. Detailed analyses integrating morphological and molecular sequence data (28S rDNA, ITS2 rDNA-region, and COI mtDNA) revealed that these belong to two species, Cardiocephaloides physalis (Lutz, 1926) and an unknown species of Cardiocephaloides. This study provides the first report of clinid fishes serving as intermediate hosts for trematodes, reveals that the diversity of Cardiocephaloides in South Africa is higher than previously recorded, and highlights the need for further research to elucidate the life cycles of these trematode species. The broad geographical distribution of Cardiocephaloides spp. was confirmed in the present study based on molecular sequence data. The host-parasite interactions between clinid fishes and metacercariae of Cardiocephaloides are yet to be explored.

Direct and heritable effects of natural tidal environments on DNA methylation in Pacific oysters (Crassostrea gigas)

Rapid climate change threatens the survival of animals, especially in vulnerable coastal ecosystems. Recent studies have shown that DNA methylation is a mechanism by which organisms can modulate current and future generations to cope with rapid environmental changes. Here, an investigation in a real-world context was conducted to determine the epigenetic mechanisms that are triggered by environmental changes in a typical intertidal species, the Pacific oyster (Crassostrea gigas). Oysters inhabiting intertidal and subtidal regions were collected, and their offspring were produced and subjected to common environment. The divergence of phenotypes and whole genome DNA methylation were assayed between the intertidal and subtidal oysters. The undifferentiated genetic structures implied that the phenotypic and epigenetic variations were mainly induced by the environment. Approximately 41% of genes modified by DNA methylation, which play a role in responses to the variable intertidal environment, could be transmitted to the next generation and had largely consistent tendency of regulation. The cross-generational genes were involved in the regulation of GTPase activity, primary metabolic activity, autophagosomes, and apoptosis, which may mediate the inheritable phenotypic divergence related to heat stress resistance between intertidal and subtidal oysters. The extent to which environmentally induced DNA methylation is inherited was evaluated here for the first time in oysters. This study provides new insights into the epigenetic mechanisms underlying biological adaptations to rapid climate change in coastal organisms.

Macrocrustaceans associated with reefs of Phragmatopoma caudata Krøyer in Mörch, 1863 (Polychaeta: Sabellariidae) and rocky shore in the Northeastern Brazil

Ecosystem engineering species create, modify, and/or maintain the characteristics of the environment. The polychaete Phragmatopoma caudata builds large sand reefs in the intertidal region of the Brazilian coast with high structural complexity, favoring the increase of diversity and interactions among the species associated. However, there are no studies concerning the association of polychaetes with crustacean macrofauna in the northeastern Brazil ecoregion, leaving an information gap on baseline biodiversity. Our aim was to analyze the effect of P. caudata colonies (PC) on the local diversity of macrocrustaceans compared to the rocky shore (RS) microhabitat. Monthly collections were carried out in low tide from September 2015 to August 2016 on 10 × 10 m quadrants for fauna and environmental variables (temperature and salinity) samples. In each microhabitat, the capture effort was two hours by two researchers. We collected 3,390 individuals, 60% associated with the colonies of PC and 40% with the RS. The PC obtained higher Shannon diversity, Pielou evenness and species richness coupled with milder water temperature and salinity conditions (minor air exposure during tide), compared to the RS that obtained greater species dominance and more extreme abiotic conditions (major air exposure). The Porcellanidae family stood out because all its species were highly abundant and had high occurrence in the colonies. The tropical Brazil porcelain crab Pachycheles greeleyi was dominant in both microhabitats (major dominance in PC). The structural complexity in the reefs of PC promoted higher availability of niches for the species, as more shelter for the resident species and refugium for temporary species with preference for more complex microhabitats. Conservation managers should prioritize the health of these colonies and subsequent species that constitute important ecosystemic and fishery resources.

Recent Advancement in Mangrove Forests Mapping and Monitoring of the World Using Earth Observation Satellite Data

Mangrove forests are distributed in the inter-tidal region between the sea and the land in the tropical and subtropical regions of the world largely between 30° N and 30° S latitude [...]

High Dimensionality of the Stability of a Marine Benthic Ecosystem

Stability is a central property of complex systems and encompasses multiple dimensions such as resistance, resilience, recovery, and invariability. How these dimensions correlate among them is focus of recent ecological research, but empirical evidence at regional scales, at which conservation decisions are usually made, remains absent. Using a field-based manipulative experiment conducted in two marine intertidal regions, we analyze the correlations among different aspects of stability in functioning (community cover) and composition of local communities facing a press disturbance. The experiment involved the removal of the local space-dominant species for 35 months in eight sites under different environmental regimes in northern- and southern-central Chile (ca. 30 and 40°S, respectively). After the disturbance, the magnitude of the initial responses and the recovery patterns were similar among communities dominated by different species, but varied between the functional and compositional response variables, and among four dimensions of stability. The recovery trajectories in function and composition remained mostly uncorrelated across the system. Yet, larger initial functional responses were associated with faster recovery trajectories—high functional resilience, in turn, was associated with both, high and low variability in the pattern of recovery. Finally, the compositional stability dimensions were independent from each other. The results suggest that varying community compositions can perform similar levels of functioning, which might be the result of strong compensatory dynamics among species competing for space in these communities. Knowledge of several, and sometimes independent, aspects of stability is mandatory to fully describe the stability of complex ecological systems.

A Study on Media Optimization, Characterization and Purification of L-Asparaginase Producing Streptomyces sp. FSOF Strain Isolated from the Bay of Bengal Coastal Line

The vast marine biodiversity provides abundant opportunities for the isolation and characterization of Streptomyces species with therapeutic applications. The present study is focused on isolation, characterization, media optimization of Streptomyces sp. FSOF strain for production and purification of L-Asparaginase at an economic level. Methods: The isolated strain from the intertidal region of Bay of Bengal coastal region is characterized by physicochemical, genotypic and by phylogenetic methods. The growth medium of Streptomyces FSOF strain is optimized for high enzyme activity and further purified by Ion exchange chromatography. Results and Conclusion: The FSOF isolate exhibited 4.3 IU/ml enzyme activity in m9 broth. The enzyme activity of the FSOF strain is further analyzed in various growth mediums where 5.9 IU/ml activity is observed in tryptic soy broth. The purified L-asparaginase from FSOF isolate exhibited 23.33 IU/mg specific activity with 3.12 fold purification. The 16s rRNA sequence of FSOF isolate is found to have 99.88% similarity with Streptomyces albidoflavius and Streptomyces odorifer strains. The sequence is further deposited in GenBank (accession number MN562193.1) for future analysis. © 2020 iGlobal Research and Publishing Foundation. All rights reserved.

A review about fish walking on land

Mudskippers are amphibious species inhabiting semi-terrestrial ecosystems like mudflats, mangroves, marshy swamps, intertidal regions, and estuaries. Around 34 diversified species are found across the globe. Mudskipper belongs to the Oxudercidae family and the subfamily is Oxudercinae. The occurrence of species is vastly found across the Indo-West Pacific region, the tropical western coast of Africa and in the Indian Ocean. Mudskippers are known for being the biological indicator and also an indicator of estuarine safety monitoring. They are used by people for prey-catching baits. This review paper explains the ecological indicators, taxonomy, species diversity, habitat, behavioural pattern, respiration & kinematics, feeding ecology, reproduction, nutrition content & its medicinal value, and threats to mudskippers.

The occurrence of vulnerable seagrass species Halophila beccarii Ascherson, 1871 from restored mangrove of Koduvally Estuary, south‐west coast of India

AbstractThe ocean turf grass, Halophila beccarii Ascherson, 1871 was recorded for the first time in the intertidal region of the restored mangrove ecosystem of the Koduvally Estuary on the south‐west coast of India. It was found co‐existing in the shallow muddy area of the mangroves, dominated by mangrove trees of Rhizophora mucronata and Sonneratia alba, and macroalgae, Ulva sp., Enteromorpha sp. and Chaetomorpha sp. The meadow is sparsely scattered with shoots near the mangroves, with a mean density of 720 shoots/m2. Details regarding the morphology and hydrographic conditions are described. The occurrence of H. beccarii in the Koduvally estuary is an encouraging sign of improved ecosystem health through mangrove restoration. The development of seagrass meadow in the estuary will improve the sediment stability and water quality. A further comprehensive study on the spatiotemporal variation of this species in the estuary is also recommended for conservation and management of this vulnerable seagrass species.

Carlgren’s hesitation allayed: redescription and systematics of Heteranthus verruculatus Klunzinger, 1877 (Cnidaria, Actiniaria), with a redefinition of Heteranthidae Carlgren, 1900

Abstract Species boundaries delineating tropical sea anemones (Cnidaria, Actiniaria) of the zooxanthellate genus, Heteranthus Klunzinger, 1877, are unclear. There are currently two valid Heteranthus species: type species Heteranthus verruculatus Klunzinger, 1877, first reported from Koseir, Egypt, and H. insignis Carlgren, 1943, from Poulo Condore, Vietnam. In describing the latter from a single, poorly preserved specimen, zoologist Oskar Carlgren expressed apprehension with traits he had used to establish this species. Carlgren’s doubts persisted later in writing when he found a similar-looking sea anemone from the Great Barrier Reef. Crucial details to positively identify either species have since remained limited. Here, we re-diagnosed Heteranthus and re-described its type species based on observations of specimens we have obtained from Singapore and Pulau Ambon (Indonesia), and of museum material collected elsewhere across the Indo-West Pacific region (n > 180). Supported by molecular phylogenetic evidence, the family Heteranthidae Carlgren, 1900 was reinstated and re-diagnosed. Heteranthus verruculatus is encountered in the lower intertidal region amongst seagrass, in rocky crevices, or coral rubble. It occurs as solitary individuals or in clonal clusters, well-camouflaged against the substratum. Individuals were observed to frequently propagate by longitudinal fission, resulting in a varied appearance. Type material of H. verruculatus and H. insignis were re-examined and as we found no differences between them, the two were synonymised. We inferred that Carlgren probably misinterpreted cnidae and histological data in defining H. insignis as a distinct species. This revision clarifies the taxonomy and geographic range of H. verruculatus, an Indo-West Pacific species that is found from the Red Sea to subtropical Australia and Hawaii.