Soft Substrate Habitat Research Articles

Spatial and temporal community composition changes of Cumacea (Crustacea: Malacostraca: Peracarida) from the soft-sediment habitats of the Mediterranean coast of Israel

The present study provides a zoogeographic and faunistic update on the cumacean species that inhabit the soft substrate habitats of the Israeli waters of the Mediterranean Sea. Published and new unpublished cumacean records are both used to enable an overview of a 74-year period of species composition and distribution, providing a broad perspective of temporal faunistic changes. As a result, 43 cumacean species have now been recorded from the Mediterranean coast of Israel. Previously unpublished results, starting from 2013, were derived from intensified sampling of the continental shelf and slope as well as the bathyal plain, and revealed eight new species records for the eastern part of the Mediterranean Sea. The cumacean community included species primarily of the Mediterranean zoogeographic province with several Mediterranean-Atlantic examples. Three species, postulated to be of Indo-Pacific origin were also previously recorded on the continental shelf of the area. Finally, species composition and structure of the continental shelf indicated spatial and temporal changes between 2010 – 2021, partly due to different sampling methods as well as anthropogenic activities that took place in the area. The continental slope and the bathyal plain seem to remain as relatively stable environments.

Biodiversity, ecology, and taxonomy of sediment-dwelling Dendrophylliidae (Anthozoa, Scleractinia) in the Gulf of Thailand

Abstract Dendrophylliidae represents one of the most speciose families of scleractinian coral, expressing a wide range of morphological and ecological traits. Recent phylogenetic analyses of the family have indicated that several conventional genera are in need of revision. In the Gulf of Thailand, dendrophylliids are predominantly found on hard-substrate reefs and pinnacles, or on soft-substrate habitats. Soft-substrate habitats in the Gulf of Thailand have been shown to host unique species assemblages and faunal ecology. Here we provided an updated phylogenetic hypothesis for the Dendrophylliidae based on newly sequenced species, and analyses integrating morphology, genetics and ecology. High-resolution Micro-ct was used to create digital versions of the studied species, allowing for non-destructive examination of internal and external features. Our findings allowed for a taxonomic assessment of the genera Heteropsammia and Tubastraea, with the species Balanophyllia (Eupsammia) stimpsonii, moved to the genus Tubastraea. They also support the polyphyly of Dendrophyllia and Cladopsammia. In-situ surveys provided population-density information for four dendrophylliid species from soft substrate habitats, indicating that the species Heteropsammia moretonensis may be the most widespread within the Gulf of Thailand. These surveys also provided novel ecological documentation associated with these corals, including protocooperative feeding upon a sea pen by Tubastraea stimpsonii comb. nov., and feeding upon other cnidarians by Heteropsammia spp.

High biogeographic and latitudinal variability in gastropod drilling predation on molluscs along the eastern Indian coast: Implications on the history of fossil record of drillholes.

Studies on the large-scale latitudinal patterns of gastropod drilling predation reveal that predation pressure may decrease or increase with increasing latitude, or even show no trend, questioning the generality of any large-scale latitudinal or biogeographic pattern. Here, we analyze the nature of spatio-environmental and latitudinal variation in gastropod drilling along the Indian eastern coast by using 76 samples collected from 39 locations, covering ~2500 km, incorporating several ecoregions, and ~15° latitudinal extents. We find no environmental or latitudinal gradient. In fact, drilling intensity varies highly within the same latitudinal bin, or oceanic sub-basins, or even the same ecoregions. Moreover, different ecoregions with their distinctive biotic and abiotic environmental variables show similar predation intensities. However, one pattern is prevalent: some small infaunal prey taxa, living in the sandy-muddy substrate—which are preferred by the naticid gastropods—are always attacked more frequently over others, indicating taxon and size selectivity by the predators. The result suggests that the biotic and abiotic factors, known to influence drilling predation, determine only the local predation pattern. In the present case, the nature of substrate and prey composition determines the local predation intensity: soft substrate habitats host dominantly small, infaunal prey. Since the degree of spatial variability in drilling intensity within any time bin can be extremely high, sometimes greater than the variability across consecutive time bins, temporal patterns in drilling predation can never be interpreted without having detailed knowledge of the nature of this spatial variability within a time bin.

Population structure of the brown-banded bamboo shark, Chiloscyllium punctatum and its relation to fisheries management in the Indo-Malay region

The brown-banded bamboo shark, Chiloscyllium punctatum is one of the most common shark species caught in coastal fisheries throughout the Indo-Malay region and the most abundant shark caught in trawl fisheries in Malaysia and Thailand. Differences in fisheries regulations related to trawling among jurisdictions, and an absence of either stock assessments or population estimates in the region, raise questions about the sustainability of fisheries that take this species. As a small-bodied, benthic shark that predominantly inhabits shallow, soft substrate habitats, the population may be particularly vulnerable to trawling throughout the region. We investigated the population structure of Chiloscyllium punctatum using genome-wide nuclear markers. Comprehensive DNA sampling was undertaken in Thailand, Malaysia and Indonesia, and population structure analysis using SNP datasets revealed at least four genetically distinct regional groups of C. punctatum. We identified a potentially shared stock between Malaysia and Indonesia, and separate populations in the Andaman Sea off Thailand, the South China Sea, and a localized population in South Sulawesi, Indonesia. Each of these stocks may likely require different management approaches tailored to the scale and types of fishing pressure in the different regions.

A molecular phylogenetic hypothesis for the Asian agamid lizard genus Phrynocephalus reveals discrete biogeographic clades implicated by plate tectonics.

Phylogenetic relationships of the agamid lizard genus Phrynocephalus are described in the context of plate tectonics. A near comprehensive taxon sampling reports three data sets: (1) mitochondrial DNA from ND1 to COI (3' end of ND1, tRNAGln, tRNAIle, tRNAMet, ND2, tRNATrp, tRNAAla, tRNAAsn, tRNACys, tRNATyr, and the 5' end of COI) with 1761 aligned positional sites (1595 included, 839 informative), (2) nuclear RAG-1 DNA with 2760 aligned positional sites (342 informative), and (3) 25 informative allozyme loci with 213 alleles (107 informative when coded as presence/absence). It is hypothesized that Phrynocephalus phyletic patterns and speciation reflect fault lines of ancient plates now in Asia rejuvenated by the more recent Indian and Arabian plate collisions. Molecular estimates of lineage splits are highly congruent with geologic dates from the literature. A southern origin for the genus in Southwest Asia is resolved in phylogenetic estimates and a northern origin is statistically rejected. On the basis of monophyly and molecular evidence several taxa previously recognized as subspecies are recognized as species: P. hongyuanensis, P. sogdianus, and P. strauchi as "Current Status"; Phrynocephalus bannikovi, Phrynocephalus longicaudatus, Phrynocephalus turcomanus, and Phrynocephalus vindumi are formally "New Status". Phylogenetic evaluation indicates a soft substrate habitat of sand for the shared ancestor of modern Phrynocephalus. Size diversity maximally overlaps in the Caspian Basin and northwestern Iranian Plateau. The greatest species numbers of six in sympatry and regional allopatry are found in the southern Caspian Basin and southern Helmand Basin, both from numerous phylogenetic lineages in close proximity attributed to tectonic induced events.

Cold-Water Coral Habitats in Submarine Canyons of the Bay of Biscay

The topographical and hydrological complexity of submarine canyons, coupled with high substratum heterogeneity, make them ideal environments for cold-water coral (CWC) habitats. These habitats, including reefs, are thought to provide important functions for many organisms. The canyons incising the continental slope of the Bay of Biscay have distinct morphological differences from the north to the south. CWCs have been reported from this basin in the late 19th century; however, little is known about their present-day distribution, diversity and environmental drivers in the canyons. In this study, the characteristics and distribution of CWC habitats in the submarine canyons of the Bay of Biscay are investigated. Twenty-four canyons and three locations between adjacent canyons were sampled using a Remotely Operated Vehicle (ROV) or a towed camera system. Acquired images were annotated for habitat type (using the CoralFISH classification system), substrate cover and coral identification. Furthermore, the influence of hydrological factors and geomorphology on the CWC distribution was investigated. Eleven coral habitats, formed by 62 morphotypes of scleractinians, gorgonians, antipatharians and seapens, inhabiting hard and/or soft substrate, were observed. The distribution patterns were heterogenous at regional and local scales; the south Bay of Biscay and the southeastern flank favored soft substrate habitats. Biogenic and hard substrate habitats supported higher coral diversities than soft substrate habitats and had similar species compositions. A higher coral species turnover characterized soft substrate habitats. Substrate type was the most important driver of the patterns in both distribution and composition. Observations of coral reefs on steeper areas in the canyons and coral rubble on flatter areas on the interfluve/upper slope, support the hypothesis that canyons serve as refuges, being less accessible to trawling, although natural causes may also contribute to the explanation of this distribution pattern. The results of this study fed into a proposal of a Natura 2000 network in the Bay of Biscay where management plans are rare.

A synthesis of genetic connectivity in deep-sea fauna and implications for marine reserve design.

With anthropogenic impacts rapidly advancing into deeper waters, there is growing interest in establishing deep-sea marine protected areas (MPAs) or reserves. Reserve design depends on estimates of connectivity and scales of dispersal for the taxa of interest. Deep-sea taxa are hypothesized to disperse greater distances than shallow-water taxa, which implies that reserves would need to be larger in size and networks could be more widely spaced; however, this paradigm has not been tested. We compiled population genetic studies of deep-sea fauna and estimated dispersal distances for 51 studies using a method based on isolation-by-distance slopes. Estimates of dispersal distance ranged from 0.24km to 2028km with a geometric mean of 33.2km and differed in relation to taxonomic and life-history factors as well as several study parameters. Dispersal distances were generally greater for fishes than invertebrates with the Mollusca being the least dispersive sampled phylum. Species that are pelagic as adults were more dispersive than those with sessile or sedentary lifestyles. Benthic species from soft-substrate habitats were generally less dispersive than species from hard substrate, demersal or pelagic habitats. As expected, species with pelagic and/or feeding (planktotrophic) larvae were more dispersive than other larval types. Many of these comparisons were confounded by taxonomic or other life-history differences (e.g. fishes being more dispersive than invertebrates) making any simple interpretation difficult. Our results provide the first rough estimate of the range of dispersal distances in the deep sea and allow comparisons to shallow-water assemblages. Overall, dispersal distances were greater for deeper taxa, although the differences were not large (0.3-0.6 orders of magnitude between means), and imbalanced sampling of shallow and deep taxa complicates any simple interpretation. Our analyses suggest the scales of dispersal and connectivity for reserve design in the deep sea might be comparable to or slightly larger than those in shallow water. Deep-sea reserve design will need to consider the enormous variety of taxa, life histories, hydrodynamics, spatial configuration of habitats and patterns of species distributions. The many caveats of our analyses provide a strong impetus for substantial future efforts to assess connectivity of deep-sea species from a variety of habitats, taxonomic groups and depth zones.

Macroinvertebrate palaeo-communities from the Jurassic succession of Gebel Maghara (Sinai, Egypt)

Macrobenthic palaeo-communities of the Middle and Upper Jurassic strata of G. Maghara, Egypt, were investigated to identify relationships with environmental parameters and to trace the temporal changes of the ecosystem associated with sea-level fluctuations. The quantitative analysis of a data matrix comprising 198 macrobenthic taxa in 138 samples collected from four sections identified nine associations and three assemblages, interpreted to be representative of their original environment. Non-Metric Multidimensional Scaling (NMDS) delineated the same degree of habitat partitioning as hierarchical clusters with very little overlap. Detrended Correspondence Analysis (DCA) identified water depth as the primary environmental gradient controlling the distribution of the fauna, while Axis 2 reflects substrate consistency. Community structure is related to the various ramp environments. Based on diversities, the associations and assemblages have been divided into two major groups, low-stress polyspecific associations and high-stress paucispecific associations. The low-stress polyspecific associations were interpreted to represent two different habitats, a high-energy, firm substrate habitat, in which epifaunal bivalves and brachiopods in addition to solitary corals dominated during advanced stages of transgression, and a low-energy, soft substrate habitat dominated by infaunal bivalves during the maximum flooding. The high-stress paucispecific associations are dominated by one or few taxa and occurred (1) in an oligotrophic setting that developed during episodes of sediment starvation in restricted inner ramp environments or during early transgression, (2) in a setting characterized by high sedimentation rates which developed during advanced regression, (3) in a distal prodelta setting with soft substrate and dysoxia during sea-level lowstand, and (4) in a high-energy shoal environment during peak regression. A combined stress involving a shortage in food supply, episodic dysoxia, in addition to a soupy substrate may have developed during maximum flooding episodes. Hydrodynamic conditions were most likely the main factor controlling the benthic communities. Hydrodynamic conditions influenced the substrate type, redistributed nutrients and were responsible for stratified water masses and hypoxia. Animal-sediment relationships in addition to replacement between bivalves and brachiopods are also discussed. Middle ramp settings were found to provide the best conditions for macrobenthos.

Recruitment of marine biota onto hard and soft artificially created subtidal habitats in Sabah Al-Ahmad Sea City, Kuwait

Remediation of coastal habitats from impacts such as dredging and excavation in Gulf coastal waters is hampered by a lack of information on natural recolonisation rates and recruitment patterns of subtidal biota. For soft substrate habitats recovery information is only available for severely polluted sites where recovery takes many years (Jones et al., 2008).Construction of the Sabah Al-Ahmad Sea City provides a unique opportunity to follow benthic recruitment and community development on a range of artificially created benthic habitats over time. The three phases completed were each flooded by the sea separately and annual ecological surveys allow comparison of colonisation patterns and community development rates over time.Species diversity similar to that seen in comparable natural open sea habitats is reached within 2–5years for mixed sand/rock biota, but longer (2–6years) for sand biota. Biotic abundance exceeds open sea levels within 1–2years due to settlement of opportunistic species. Coral recruitment occurred within 3years. Present data provides a reference point for recovery rates into none polluted benthic habitats for the Gulf.

Cold seeps and benthic habitat on the Pacific margin of Canada

Cold seeps on the Pacific margin of Canada occur in 130 m water depth in an actively trawled region of Hecate Strait. The seep sites are located within a NW/SE orientated linear pockmark chain. Within the largest of the pockmarks, actively venting authigenic carbonate chimneys (mounds) occur, and the chimneys are surrounded by a wide halo of shells and shell debris. The faunal assemblage found at the cold seeps is unique from that of the surrounding soft substrate habitat and is not typical of other cold seep communities. All taxa are relatively common species found on the British Columbia continental shelf, although some, such as the Oregon triton ( Fusitriton oregonensis) were in unusually high abundance for a habitat dominated by soft substrate. These taxa were apparently attracted by the presence of hard substrate in an otherwise soft seabed environment, especially those sessile organisms, such as giant plumose anemones ( Metridium giganteum) and encrusting sponges that require hard substrate for attachment. No direct evidence could be found that linked the presence of any epifauna to the presence of hydrocarbons; however the presence of the gutless clam Solemya reidi and high abundance of Oregon triton strongly implies a relationship to the cold seeps. The significant preservation of shell debris that surrounds the carbonate chimneys suggests that the chemistry of the near-seabed water has been altered, due to the presence of the hydrocarbon seepage. The exposure of the carbonate chimneys is a result of discontinuous expulsion of thermogenic gas and continued deepening of the pockmarks.

Temporal variability of a benthic food web: patterns and processes in a low-diversity system

Trophic interactions are not static links, but are dynamic both in space and time. In tem- perate environments, seasonal patterns in primary production may be pronounced and, hence, the zoobenthic community and the trophic couplings within it change during the main production sea- son. We assessed temporal variability in a benthic food web using stable isotope ratios of C and N. Organisms belonging to 3 trophic levels, producers (e.g. macroalgae and vascular plants), primary consumers (macrozoobenthos) and secondary consumers (epibenthic fishes and Crangon crangon), were sampled monthly in a shallow soft-substrate habitat in the northern Baltic Sea. The study focused on intra-seasonal (main production period from June to September 2005) and inter-annual (comparing data collected in June of 2 consecutive years) variability of trophic interactions involving phyto- and zoobenthos. Intra-seasonal changes in stable isotope ratios of food web components occurred both on a horizontal (within a trophic level) and a vertical scale (between trophic levels). Generally, unimodal patterns were evident, with enrichment of 13 C and depletion of 15 N occurring during the production period. The fluctuation in stable isotope values over the season decreased with increasing trophic level. Predator stable isotope values are probably affected by changes at the base of the food web and changes in consumer diet. The intra-seasonal pattern, together with limited interannual variability, indicates a temporally stable food web structure.

Palaeoecology of solitary corals in soft-substrate habitats: the example of Cunnolites (upper Santonian, Eastern Alps)

The upper Santonian Hofergraben Member (Eastern Alps) provides an example of a soft-substrate habitat suited mainly for solitary corals (Cunnolites), for colonial forms of solitary coral-like shape (Placosmilia, Diploctenium), and for colonial corals of high sediment resistance (e.g. Actinacis, Pachygyra). The Hofergraben Member consists mainly of silty-sandy marls of wave-dominated, low-energy shore zone to shallow neritic environments. Substrates of soft to firm mud supported level-bottoms of non-rudist bivalves, gastropods, solitary corals, colonial corals, rudists, echinoids, and benthic foraminifera. Boring and/or encrustation of fossils overall are scarce. In the marls, Cunnolites is common to abundant. Both a cupolate shape and a lightweight construction of the skeleton aided the coral to keep afloat soft substrata. Cunnolites taphocoenoses are strongly dominated by small specimens (about 1–3 cm in diameter). Cunnolites was immobile and mostly died early in life upon, either, smothering during high-energy events, rapid sedimentation associated with river plumes, or by toppling and burial induced by burrowing. Comparatively few large survivor specimens may show overgrowth margins interpreted as records of partial mortality from episodic sedimentation or tilting on unstable substrate. Scattered pits and scalloped surfaces on large Cunnolites may have been produced, in some cases at least, by predators (durophagous fish?). Post-mortem, large Cunnolites provided benthic islands to corals, epifaunal bivalves and bryozoans. In a single documented case of probable in vivo contact of Cunnolites with the colonial coral Actinastraea, the latter prevailed.

Using a theoretical ecospace to quantify the ecological diversity of Paleozoic and modern marine biotas

The process of evolution hinders our ability to make large-scale ecological comparisons—such as those encompassing marine biotas spanning the Phanerozoic—because the compared entities are taxonomically and morphologically dissimilar. One solution is to focus instead on life habits, which are repeatedly discovered by taxa because of convergence. Such an approach is applied to a comparison of the ecological diversity of Paleozoic (Cambrian–Devonian) and modern marine biotas from deep-subtidal, soft-substrate habitats. Ecological diversity (richness and disparity) is operationalized by using a standardized ecospace framework that can be applied equally to extant and extinct organisms and is logically independent of taxonomy. Because individual states in the framework are chosen a priori and not customized for particular taxa, the framework fulfills the requirements of a universal theoretical ecospace. Unique ecological life habits can be recognized as each discrete,n-dimensional combination of character states in the framework. Although the basic unit of analysis remains the organism, the framework can be applied to other entities—species, clades, or multispecies assemblages—for the study of comparative paleoecology and ecology. Because the framework is quantifiable, it is amenable to analytical techniques used for morphological disparity. Using these methods, I demonstrate that the composite Paleozoic biota is approximately as rich in life habits as the sampled modern biota, but that the life habits in the modern biota are significantly more disparate than those in the Paleozoic; these results are robust to taphonomic standardization. Despite broadly similar distributions of life habits revealed by multivariate ordination, the modern biota is composed of life habits that are significantly enriched, among others, in mobility, infaunality, carnivory, and exploitation of other organisms (or structures) for occupation of microhabitats.

Variability in the life cycle ofRhizoclonium riparium (Roth) Harv. (Chlorophyceae: Cladophorales) under Dutch estuarine conditions

1. The reproduction of a considerable number of populations of the green algaRhizoclonium riparium from hard substrates (wooden poles, dike slopes in the intertidal zone) and soft substrates (tidal marshes and meadows) was studied in unialgal cultures. 2. In the hard substrate habitat the sexual reproduction by gametes and the asexual reproduction by quadriflagellate zoospores are strongly repressed in favour of the asexual reproduction by biflagellate zoospores. 3. In the soft substrate habitat no sexual and hardly any asexual spores are produced; the largest number of samples remain sterile. 4. It is suggested that, running parallel to an increasing instability of the habitat, expressing itself in strong fluctuations in environmental factors, a decreasing capacity ofRhizoclonium riparium to produce spores manifests itself. Reduced salinity, as well as high concentrations of nitrogen compounds may also repress sexual capacity, as indicated by recent literature.