Midlittoral Zone Research Articles

A new species of Batillipes (Arthrotardigrada: Batillipedidae) from the mid littoral zone of the southeast coast of India.

Studies of marine tardigrades from Indian waters is very limited and relatively obscure. A new species of marine tardigrade is described from the southeast coast of India as part of an effort to better understand the marine tardigrade biodiversity of the Indian subcontinent. Batillipes kalami sp. nov. described from the sandy sediments of the mid littoral zone can be differentiated from all its congeners by the presence of unconstricted primary clavae, two pairs of lateral body projections between leg II and leg III, long and blunt ended lateral body projections between leg III and leg IV, shape of leg IV sensory organs and the presence of dorsal indentations in its head.

Morfološka i reproduktivna fenologija alohtone crvene alge Caulacanthus okamurae Yamada (Gigartinales, Caulacanthaceae) na području slovenske obale (Tršćanski zaljev, sjeverni Jadran)

This study reports the occurrence of the non-native red alga Caulacanthus okamurae, previously unknown on the Slovenian coast (Gulf of Trieste, northern Adriatic Sea). The distribution of the species, its abundance, morphological characteristics and reproductive phenology are described. The study is based on seasonal sampling conducted during one year, from winter to autumn 2021, on two different substrates (limestone and sandstone) of the midlittoral zone, and showed a moderate variation in the biomass of C. okamurae populations between the winter-spring and summer-autumn periods. The native algal assemblages of the two substrates impacted by C. okamurae were characterized by generally limited species diversity and consisted mainly of small-sized species with simple morphology. During the study, in addition to non-fertile thalli of C. okamurae, tetrasporophytic thalli with tetrasporocysts and female gametophytes with cystocarps were found.

Population structure of the invasive bivalve isognomon bicolor (C.B. Adams, 1845) on rocky beaches in northeastern Brazil

The invasive bivalve Isognomon bicolor is native to the Caribbean and had its first record for the Brazilian coast published in 2002. The objective of this study was to compare the population structure of I. bicolor in two rocky beaches of the coast of Paraíba and verify its temporal variation. Six samples (20 x 20 square cm) were collected on each beach, three in the dry season and three in the rainy season and at two levels of the mid-coastal zone (Bottom and High). Nine samples were obtained for each beach per month, totaling 108 samples. 2,196 specimens of I. bicolor were collected and measured. The highest densities occurred at Carapibus beach. Considering the size structure, there was a significant difference in the length of the nacreous layer between beaches, mid-littoral zones and seasons, with most recruits and smaller individuals occurring on Jacumã beach.

Spatiotemporal distribution and population structure of Clibanariussymmetricus(Randall, 1840) (Crustacea, Diogenidae) in an Amazon estuary

Rocky outcrops in the intertidal zones of estuaries often contain a highly diverse microbenthic community which includes the hermit crab, Clibanarius symmetricus, an abundant species on the equatorial Amazon coast. However, the ecology of this anomuran is poorly understood. Given this, the present study investigated the spatiotemporal distribution and structure of the C. symmetricus populations that inhabit the rocky outcrops of the Marapanim estuary in northern Brazil. Samples were collected monthly over a yearly cycle covering both the dry and rainy seasons in the upper and lower midlittoral zones during low tide. The distribution and abundance of C. symmetricus were affected directly by environmental factors such as temperature, seasonality, the intertidal zone, and salinity. The population presented sexual dimorphism, with males being larger than females, a male-biased sex ratio (1.5:1), a nonnormal and unimodal distribution, continuous reproduction, and sexual maturation at a cephalothoracic shield length of 3.6 mm. Despite the unique characteristics of the Amazon coast and the study estuary, the spatiotemporal distribution and structure of the C. symmetricus population were similar to those recorded at higher latitudes.

The effect of Cystoseira canopy on the value of midlittoral habitats in NW Mediterranean, an emergy assessment

There is a strong scientific consensus that coastal marine ecosystems, and in particular the midlittoral zone, at the interface between terrestrial and marine realms, are seriously threatened by anthropogenic impacts, along with the goods and services they provide. Along Mediterranean shallow rocky reefs, brown macroalgae belonging to the Cystoseira genus (e.g. Cystoseira amentacea and Cystoseira compressa) are ecosystem engineers, locally creating a continuous fringe in the midlittoral zone, supporting high biodiversity and productivity and providing ecosystem services. A growing interest in the quantification of ecosystem relevance through their economic value aims at raising public awareness and supporting policy-makers in the process of creating new legal instruments supporting the preservation of biodiversity. In this framework, a methodology for ecological and monetary evaluation of natural capital, based on biophysical accounting and on emergy theory, is applied to the habitats of the upper midlittoral zone located above continuous and non-continuous Cystoseira fringe. The proposed approach is a quantitative measure able to analyse the overall functioning of the system and its efficiency in exploiting available resources. The mean economic value of the habitats in the midlittoral zone assessed through the present study is 1.28 em€/m2. Higher values, but associated with a larger variability, were observed in presence of continuous C. compressa fringe. Conversely, in the presence of a continuous C. amentacea fringe, a noticeable habitat-forming species, lower natural capital values were recorded possibly due to the attractive potential of this species in its understorey rather than in the above habitats, concurrently with a lower variability of the natural capital values (lower scatter), suggesting a deterministic homogeneity effect on the above midlittoral habitats. From this study, emergy analysis is confirmed to represent an effective and operative tool to provide a synthetic monetary assessment of natural capital making complex information easily accessible to different stakeholders, from general public to territorial managers.

Comparative population biology and reproduction of two sympatric crabs (Grapsidae) on Azores cobble beaches

ABSTRACTPopulation biology of the intertidal crabs Pachygrapsus marmoratus Fabricius, 1787 and P. maurus (Lucas 1846) was investigated at cobble beaches with different levels of wave exposure. Surveys were taken monthly over 1.5 years at three intertidal levels. The growth rate of both species was similar, although P. marmoratus reached larger sizes. This species was more abundant on the mid-littoral zone of sheltered beaches, whereas P. maurus was more abundant on more exposed ones. The sex ratio was male biased in both species, particularly for the smaller and larger size classes. Both species showed an extended reproductive season, coinciding with the rising temperatures of spring and summer, with ovigerous females being found from June to September for P. marmoratus and from May to August for P. maurus. The present study indicates that both could develop adaptive strategies allowing them to coexist in the Azores littoral. The greater size of P. marmoratus seems to be an advantage on the competition for refuges with P. maurus, which results in its higher abundance and general dominance in the higher shore levels and in less exposed shores. However, P. maurus seems to be more fitted to live in the higher hydrodynamic habitats.

Riqueza y distribución vertical de los moluscos del litoral rocoso de la provincia de Islay, Arequipa, al sur del Perú

El litoral rocoso es un ecosistema heterogéneo en el que se distinguen una franja supralitoral, una zona mediolitoral y una franja infralitoral, al reconocer a las especies de moluscos como indicadoras de una zonación vertical. Este trabajo contribuye al conocimiento de la riqueza y la distribución vertical de los moluscos intermareales para la provincia de Islay, Arequipa, Perú. Se realizó una búsqueda intensiva en los meses de noviembre y diciembre del año 2013, para poder determinar la riqueza y se establecieron tres cuadrantes de 25 x 25 cm de lado distribuidos perpendicularmente a la línea costera con 14 repeticiones en los 7 sitios de estudio, para establecer su distribución vertical. Se utilizó un análisis de componentes principales (ACP), un escalamiento multidimensional no métrico (nMDS) y curvas de rango-abundancia para la determinación de la distribución vertical, y un análisis de similaridades (ANOSIM) para determinar diferencias entre la composición de moluscos entre los sitios de estudios y las subzonas del litoral. Se encontraron un total de 57 taxones, donde Echinolittorina peruviana fue la especie más representativa en la franja supralitoral, Perumytilus purpuratus para la zona mediolitoral y Tegula atra para la franja infralitoral. No se presentaron diferencias significativas en la composición de moluscos entre los sitios de estudio, pero sí entre las subzonas, al ser la zona mediolitoral la que presentó mayor riqueza y abundancia de organismos. La similitud fue mayor entre las subzonas medio e infra- con respecto a la supralitoral.

Identifying benthic macrofaunal assemblages and indicator taxa of intertidal boulder fields in the south of the Bay of Biscay (northern Basque coast). A framework for future monitoring

The French southern marine subregion of the Bay of Biscay presents local environmental features explaining the presence of specific communities in remarkable habitats. The aim of the study is, for the first time, to assess benthic macrofaunal assemblages and to identify indicator species of each assemblage within intertidal boulder field habitats in this marine subregion.Mobile boulders were sampled with a stratified random sampling design in upper and lower midlittoral zones in March–June 2015. Sessile (in percentage cover) and mobile macrofauna (in abundance) communities were identified and counted within 0.1 m2 quadrats. Ecological function and precision between the two groups were found dissimilar thus species richness, abundance, macrofauna distribution and indicator species/taxa of sessile and mobile macrofauna were analyzed separately. 78 species/taxa of macrofauna were recorded. A restricted list of 12 singletons (8 for mobile and 4 for sessile macrofauna) and 33 combinations of species/taxa were identified as significant indicators of each assemblage. Species ecological features (food webs, signs of disturbance, alien species, biogeographical range limit) were also considered as additional selection criteria. Therefore, species with a high ecological interest but not considered statistically as valid indicators were also highlighted.Thus, this work constitutes a framework for future monitoring of the Basque intertidal rocky shore and could be used as an alternative to sampling the entire biodiversity. It also meets the MSFD requirements (e.g. take into account marine subregion specificities; integrate the metric “macrofauna” and supports several descriptors as the D1 “Biodiversity” and D6 “Seafloor integrity”).

Hermaphroditism in Brachidontes pharaonis (Fischer, 1876) (Bivalvia: Mytilidae) from the Alexandria Coast, Egypt

Brachidontes pharaonis (Fischer, 1876) was widely reported to cover completely hard substrates especially rocky shores with higher density in mid-littoral zones forming mytilid beds along Alexandria Coast, Egypt. During our study on the reproductive cycle of this species, one case out of 307 examined specimens was found to be hermaphrodite representing only 0.33% of the total sample. It had a shell length 28.25 mm and was collected during January 2017. The sex ratio of this population is different from 1:1, although this deference was not significant (X2 = 11.118, df = 11, P > 0.05). In this contribution, this case of hermaphroditism in B. pharaonis is described. The histological study showed the presence of male and female gametes in the same follicle and this was the most common situation in both lobes of the mantle. The male zone was showing different stages of spermatogenesis together with the female zones showed different stages of oogenesis with occurrence of young oocytes attached to the follicle wall.

The vertical distribution and abundance of Chthamalus stellatus Poli and Chthamalus montagui Southward (Crustacea, Cirripedia) at two localities of the Istrian peninsula coast (North Adriatic)

Two species of chthamalid barnacles are well established from the upper to the lower limit of the midlittoral zone on the rocky shores of the North Adriatic Sea: Chthamalus stellatus, Poli and Chthamalus montagui, Southward. The present study deals with the vertical distribution and abundance for each species at two localities of the Istrian peninsula coast (North Adriatic Sea). For this purpose chthamalid populations were monitored in 2015 along the Slovenian marine coast (Bay of Koper, Gulf of Trieste) and along the Croatian marine coast, near Rovinj (west Istrian coast), both on limestone. The main aim of the study was to establish if there was a relationship between the vertical distribution and abundance of these two species at different spatial scales: small (between sites, about 1 kilometer) and large (between localities, 10s of kilometers). The selected localities are slightly different in tidal range, in orientation and wave exposure. Three sites were randomly selected at each locality and two transects per tidal level (upper, middle and lower) were chosen on each site. The abundance of each chthamalids species in 1 dm2 plots was determined at three different tidal levels along each transect. The results indicated that the vertical distribution of C. montagui and C. stellatus was very similar between localities and even among sites, but their abundance varied. At both localities, C. montagui was more abundant in the upper and middle tidal levels, while C. stellatus was more abundant at the lower tidal level. It was also found that C. montagui was more abundant in sheltered conditions (Bay of Koper), while C. stellatus on the coast more exposed to the wave action (near Rovinj), at all tidal levels.

Response of rocky shore communities to anthropogenic pressures in Albania (Mediterranean Sea): Ecological status assessment through the CARLIT method

The lower mid-littoral and shallow subtidal communities were studied in the district of Vlora (Albania), three years after the establishment of a Marine Protected Area, with particular attention to the long-lived species. The bioconstructions built in the mid-littoral zone by the calcified rhodobiont Lithophyllum byssoides were in poor condition and sometimes even dead. In contrast, the brown alga Cystoseira amentacea constituted lush stands. For assessing the ecological status of the studied area, the CARLIT method, based upon macroalgal communities, was applied. The observed range of ecological status was wide (‘high’ through ‘bad’) and was overall among the lowest assessed to date in the Mediterranean Sea. The occurrence of extensive sea-urchin barren-grounds, though not taken into consideration by the CARLIT index, confirmed the poor condition of large sectors of the study area. Overall, the CARLIT index is well correlated with anthropogenic pressures, as assessed by the LUSI index.

수온에 따른 지중해담치 (Mytilus galloprovincialis; Bivalvia) 의 여과율과 섭식율 변동

This study was performed to describe the influence of temperature on the clearance rate and ingestion rate of the blue mussel, Mytilus galloprovincialis with three food organisms and habitat location (shell size) of mussel. Food organisms used in this experiments were Isochrysis galbana, Chaetoceros didymus and Prorocentrum dentatum. The size of mussels inhabiting higher midlittoral zone was smaller than those of lower midlittoral zone. Regardless of the kind of food organisms, filtration rates and ingestion rates of higher midlittoral mussels were higher than those of lower midlittoral mussels in experiment temperature conditions. The variation of filtration rate and ingestion rate showed same tendency with temperature. Filtration rates and ingestion rates increased with temperature, and recorded maximum values at 20-25℃ of temperature, and thereafter decreased gradually. Theoretical optimum temperatures showing maximum filtration rates and ingestion rates estimated from polynomial regression curves were also in the range of 20-25℃. Blue mussels showed different variation of filtration rate and ingestion rate with the kind of food organisms. Filtration rates and ingestion rate based on cell number were similar regardless of habitat location(tidal elevation) and food organisms. Ingestion rates based on carbon content showed very high values in case of P. dentatum beside I. galbana and C. didymus as food organism. Keyword : filtration rate, clearance rate, ingestion rate, water temperature, food organism, tidal elevation, Mytilus galloprovincialis

Different settlement strategies explain intertidal zonation of barnacles in the Eastern Mediterranean

The Mediterranean mid-littoral zone is inhabited by two sympatric chthamalid barnacles: Chthamalus stellatus and Euraphia depressa, C. stellatus extends from the high midtidal zone, above the algal belt, to the supra-littoral fringe, E. depressa is restricted to the uppermost intertidal levels in wave-beaten places and to cryptic habitats lower on the shore within the belt of C. stellatus. Previous studies have suggested that the reason for the fragmented distribution pattern of E. depressa is competitive displacement by the sympatric C. stellatus, following random settlement. This hypothesis is in agreement with the common model of zonation suggested by Connell that lower distribution limits are determined by biotic factors (competition and predation), while upper limits are set by physical factors. It is hard to test the validity of this model for this barnacle pair since the early ontogenetic stages of the species are morphologically indistinguishable, hindering our ability to understand distribution processes. Using 16S mtDNA as a genetic marker in a multiplex PCR system, cyprids and spats were individually identified. Settlement and recruitment rates were assessed using settlement plates, and the effect of post-settlement processes was tested with transplantation of settlers between zones. Results showed different strategies in each species: settlement of E. depressa was habitat-specific, while settlement of C. stellatus was random. Shifting individuals of C. stellatus to the high and cryptic zones resulted in high mortality; however, exposing juveniles of E. depressa that settled in artificially cryptic low shore habitat to C. stellatus presence had no effect on their survival. These finding do not agree with the formerly suggested hypothesis that zonation is mainly determined by post-settlement factors, and that the interspecies boundary is determined by interspecific competition, implying that competition model cannot be adapted to Mediterranean intertidal zonation and that other models, dominated by physical enforcement and pre-settlement recruitment-limiting factors, may prevail in this ecosystem.

MidMedPol: Polychaetes from midlittoral rocky shores in Greece and Italy (Mediterranean Sea).

This paper describes a dataset of polychaetes (Annelida) from 14 midlittoral rocky shore sampling sites in Greece and Italy (Mediterranean Sea). The dataset combines the outcome of four different projects studying the hard substrate midlittoral zone in the Mediterranean between 1984 and 2009. Samples were collected by scraping and collecting the organisms from a framed area. The maximal sampling depth was 1.5 m. In total, 123 polychaete species were recorded, five of which are new records for the respective biogeographic sectors of the Mediterranean. The dataset contains 788 occurrence records, fully annotated with all required metadata. These data contribute to the knowledge of a previously very understudied regional habitat, since at present, comprehensive lists of the midlittoral communities in the Mediterranean are provided through only a few, paper-based, studies. This dataset is one of the first electronic data compilations of the Mediterranean midlittoral zone communities and certainly the most comprehensive of its kind, contributing to the ongoing efforts of the Ocean Biogeographic Information System (OBIS) which aims at filling the gaps in our current knowledge of the world's oceans. It is accessible at http://ipt.vliz.be/resource.do?r=mediterraneanpolychaetaintertidal.

First report of the North Atlantic myrionematoid brown alga Ulonema rhizophorum Foslie (Phaeophyceae, Chordariaceae) in the Mediterranean Sea

The myrionematoid brown alga Ulonema rhizophorum Foslie (Phaeophyceae, Chordariaceae) is reported for the first time from the Mediterranean Sea. This species was collected growing as an epiphyte on Ulva sp. from the Dardanelles (Sea of Marmara, Turkey) in the midlittoral zone. Ulonema rhizophorum is characterized by downwardly produced rhizoids from the basal system. A key to the Mediterranean related genera of Ulonema is provided.

First report of the North Atlantic myrionematoid brown alga Ulonema rhizophorum Foslie (Phaeophyceae, Chordariaceae) in the Mediterranean Sea

The myrionematoid brown alga Ulonema rhizophorum Foslie (Phaeophyceae, Chordariaceae) is reported for the first time from the Mediterranean Sea. This species was collected growing as an epiphyte on Ulva sp. from the Dardanelles (Sea of Marmara, Turkey) in the midlittoral zone. Ulonema rhizophorum is characterized by downwardly produced rhizoids from the basal system. A key to the Mediterranean related genera of Ulonema is provided.

Gracilaria viridis sp. nov. (Gracilariales, Rhodophyta): a new red algal species from the Mediterranean Sea

Sfriso A., Wolf M.A., Sciuto K., Morabito M., Andreoli C. and Moro I. 2013. Gracilaria viridis sp. nov. (Gracilariales, Rhodophyta): a new red algal species from the Mediterranean Sea. Phycologia 52: 65–73. DOI: 10.2216/12-007.1We characterized a new Gracilaria species from the Venice Lagoon, Italy, using molecular analyses based on the plastid large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase gene (rbcL) and the intergenic RuBisCO spacer (rbcL-rbcS), combined with morphology data. This new entity was recorded on the artificial substrata of the Venice Gulf from March to July, adding to 12 Gracilaria taxa already recorded in the Mediterranean and Adriatic seas. Thalli exhibited a green-yellowish pigmentation with pink shades, and there was dense branching in the distal portions. Tetrasporangia were scattered on thallus cortex and distributed mostly on short, stipitate branchlets. The inner pericarp was connected to the gonimoblast by tubular nutritive cells. The male gametophytic plants formed round-elliptical spermatangial verrucosa-type conceptacles. This species grew attached on artificial rocky substrata of the low midlittoral and upper sublittoral zone in spring and early summer. Molecular analyses based on the plastid-encoded rbcL gene showed a 99.66% nucleotide identity with another Gracilaria sp. from southern Sicily. We compared our rbcL-rbcS spacer sequences with those of two cryptic species, and the phylogenetic analyses confirmed that the Venice populations were a new species. We suggested that the discovery of this new species was not due to an extra-Mediterranean introduction but the consequence of its misidentification as Gracilaria gracilis, which has a similar gross morphology.

Tidal notches: A sea-level indicator of uncertain archival trustworthiness

In this paper, after a short summary on the processes and rates of bioerosion that contribute to the deepening of a tidal-notch profile, some Mediterranean case-studies are presented, where a tidal notch is prevented either from forming or from being preserved. Furthermore, as shown also in a complementary paper, the recent global sea-level rise is preventing the development of new tidal notches in the present mid-littoral zone. This very useful sea-level indicator, of past temporary standstills of the relative sea level in carbonate rock areas, is of great value in assisting interpretations of relative sea-level change in locations where it is preserved. The possibilities of absence of formation or of preservation, however, imply that it should be interpreted carefully before reconstructing local relative sea-level histories. In particular, the lack of fossil tidal notches cannot be relied upon to interpret the absence of past periods of relative sea-level stabilization.

Global sea-level rise and the disappearance of tidal notches

The recent rise in global sea level is causing the disappearance of an important geomorphological sea-level indicator, the tidal notch.Tidal notches have often been used in carbonate coasts for Quaternary and late Holocene sea-level reconstructions and estimation of tectonic movements, especially in uplifting areas. In this paper, we review the rates of tidal notch development, and examine the recent gradual depletion of this feature, during at least the last century, and its relation to the increasing rates of sea-level rise. Some examples of tidal notch development are provided with fossil submerged notches from Greece. Although tidal notches are no longer forming in the present-day mid-littoral zone, underwater marks on carbonate cliffs may still provide evidence of submerged tidal notches corresponding to former sea-level positions, or of recent vertical shoreline displacements of seismic origin.

First report of the alien brown alga Scytosiphon dotyi M.J. Wynne (Phaeophyceae, Scytosiphonaceae) in Turkey

The alien brown alga Scytosiphon dotyi M.J. Wynne (Phaeophyceae, Scytosiphonaceae) is reported for the first time in Turkey. This species was collected growing epilithically in the midlittoral zone in the Dardanelles (Sea of Marmara, Turkey).