Macrotidal Sandy Beach Research Articles

Patterns in macrobenthic diversity in the lower shore of northeastern Atlantic macrotidal sandy beaches

Patterns in macrobenthic diversity in the lower shore of northeastern Atlantic macrotidal sandy beaches

Do recreational activities affect macrofauna distribution pattern in Amazonian macrotidal sandy beaches?

Recreational activities are important source of disturbance on sandy beaches and have a negative effect on benthic communities as they alter species abundance, diversity, and/or distribution. Here, we report for the first time the effects of the recreational activities on the distribution pattern of macrobenthic communities of Amazonian sandy beaches. Sampling was performed during three consecutive months with different beach use intensity in 2017 (before, during vacation, and one month after the vacation period) on two contrasting beaches regarding disturbance (Urban: Atalaia; and Protected: Corvinas) in the intertidal zone along two equidistant transects at seven equidistant sampling stations: from the high-tide water mark to the swash zone. At each sampling station, four biological and sediment samples were randomly collected. Also, in each station, the sediment compaction was determined using a manual penetrometer. Physical sediment variables remained constant over time in both beaches, whereas differences were found in sediment compaction over the periods. Sediment compaction was considered the most important factor for the differences observed in macrobenthic community structure in the study beaches, and it was related to intensity of recreational activities. Variations in density and changes in richness between periods and sampling stations were observed in Atalaia beach. On the other hand, Corvinas beach remained the same throughout the study. Overall, three faunal zones were distinguished: upper intertidal, intermediate intertidal, and low-intertidal, whereas in the vacation period, only two faunal zones were distinguished: upper-intertidal and intermediate-low intertidal.

Effects of the ridge‐and‐runnel system on macrofaunal spatial distribution on a macrotidal sandy beach in the Brazilian Amazon coast

AbstractRidge‐and‐runnel systems are common morphological features across the intertidal zone of dissipative macrotidal beaches. However, these systems have often been overlooked by macrofaunal zonation studies. The present study investigated the effects of this system on the spatial distribution of the macrofaunal community on an Amazonian macrotidal sandy beach. Samples (macrobenthos and sediments) were collected at seven equidistant levels (50 m apart) from the high tide water mark to the swash zone, in two different areas: (1) with and (2) without ridge‐and‐runnel systems. The results showed a significant increase in macrofaunal abundance and richness in area with runnels, associated with muddier sediment and higher organic content. The macrofauna in the runnels, both in upper‐intertidal and lower‐intertidal zones, had higher density and richness than that in the sandbars. There was no difference between tidal levels in area 2, although we observed an increasing tendency of abundance and richness towards the low tide line. Taxonomic composition and trophic groups also differed between areas, with predominance of species that are typical of sandy‐mud substrate and higher participation of nonselective deposit feeders in area 1. Predatory species typical of sandy substrates prevailed in area 2. These findings add knowledge to sandy beach ecology and indicate the importance of including aspects of habitat complexity in both across‐ and alongshore macrofaunal distribution studies.

Anthropogenic litter on the macrotidal sandy beaches of the Amazon region.

Coastal zones, which are strategic points of considerable importance to the tourism industry, are among the environments most affected by anthropogenic debris. Thus, it is crucial to monitor and implement management programs to provide immediate solutions. Here, we aimed to evaluate anthropogenic litter along 21 macrotidal sandy beaches in the Amazon region. Indices and multivariate statistical analyses were used to identify spatial patterns of pollution, as well as sources and lifetime of the items. A total of 20,286 items were collected, with an average density of 0.19 items/m2 and a predominance of plastics. Litter was associated with tourist and recreational activities. The lifetime of most items was <1year. All beaches had intermediate levels of pollution. The analyses identified varying patterns of anthropogenic litter related to the cleaning frequency and waste item typologies. In conclusion, pollution of macrotidal beaches in the Amazon region is an emerging problem that requires measures to prevent and mitigate the impacts on this ecosystem and to reconsider the form of production and consumption of plastic waste.

Effects of vehicle traffic and trampling on the macrobenthic community of Amazonian macrotidal sandy beaches

AbstractWe report for the first time the effects of vehicle traffic and beachgoer trampling on macrobenthic communities of Amazonian sandy beaches. Sampling was performed during four consecutive months with different beach use intensity in 2017 (before, during vacation, and two months after the vacation period) on three contrasting beaches with regard to disturbance (Urban: Atalaia; Intermediate: Farol-Velho; and Protected: Corvinas) in the intertidal zone along two equidistant transects at seven equidistant sampling stations from the high-tide water mark to the swash zone. At each sampling station, four biological and sediment samples were randomly collected. Also, in each station, the sediment compaction was determined using a manual penetrometer. Physical sediment variables remained constant over time in all beaches, whereas differences were found in sediment compaction over the months. Macrobenthic community differences in density and richness among months were observed at Atalaia and Farol-Velho beaches. In contrast, Corvinas beach remained constant throughout the study period. Furthermore, the vulnerability of the polychaetesThoracophellia papillata,Scolelepis squamataandParaonissp. indicates that they might be potential indicators of recreational activity impact.

Brachyuran crab diversity and the population biology of Panopeus americanus on a tropical Sabellariidae (Polychaeta: Annelida) reef

This paper describes the species composition, abundance, and diversity of brachyuran crabs and the population structure of Panopeus americanus on a Sabellaria wilsoni reef on Caixa D’Água beach, a macrotidal sandy beach on the Amazon coast. Samples were collected monthly throughout a single natural growth–destruction cycle of the reef. Ten crab species were recorded, of which the most abundant were Panopeus americanus (83% of the individuals collected), Panopeus occidentalis (6.8%), and Menippe nodifrons (5.3%). The highest crab species richness was recorded during the eroded reef phase, reflecting the increase in habitat complexity, whereas the highest crab density was recorded during the reef recuperation period, reflecting an intense recruitment process. Juveniles and adults (including ovigerous females) of P. americanus and P. occidentalis were found at certain times on the reef, while for M. nodifrons, the largest species, most of the captured individuals were juveniles, and no ovigerous females were captured. These findings reflect the importance of the biogenic substrate provided by the S. wilsoni reef to the population biology of the crabs on the Amazon coast, with some species using the reef more permanently, including as breeding and nursery grounds. The results also showed that the structural cycle of bioconstructions determines changes in the crab assemblages.

Patterns of spatial and temporal distribution of the macrobenthic fauna on an estuarine macrotidal sandy beach on the Amazon coast (Brazil)

AbstractSeveral attempts have been made to find universal zonation schemes for the benthic fauna in sandy beaches. Usually, the nature and number of zones are not fixed and depend on the beach type and temporal changes in environmental characteristics. We characterized spatial and temporal variations in the structure of macrobenthic communities on an Amazonian macrotidal sandy beach (Farol Beach, Algodoal‐Maiandeua Island, Brazil). Samples (macrobenthos and sediments) were collected during the rainy (March 2012 and 2013) and dry seasons (September 2011 and 2012) at six equidistant sites (50 m apart) from the high tide water mark to the swash zone. The physical gradients influenced the faunal distribution, with significant seasonal variations. Density and diversity increased seaward, while increasing moisture, organic matter content, and fine grains in sediments. Two faunal zonation schemes were observed. In the dry season, three faunal zones were distinguished: upper‐intertidal, mid‐intertidal, and low‐intertidal, whereas in the rainy season, only two faunal zones were distinguished: upper‐intertidal and low‐intertidal. In the rainy season, the physical gradients along the intertidal appeared to be smooth, allowing the expansion of the upper‐tidal zone. This study provides novel insights into macrobenthic distribution patterns, reinforcing that tropical macrotidal beaches have unique characteristics that strongly influence macrobenthic distribution patterns.

Recreational activities trigger changes in meiofauna and free-living nematodes on Amazonian macrotidal sandy beaches

Sandy beaches are key economic assets worldwide, however, recreational activities are an important source of disturbance in these ecosystems. Intensive human use of beaches has a negative effect on benthic communities as it alters species abundance, diversity, and/or distribution. Here, we report the impacts of recreational activities (trampling and vehicles) on meiobenthic communities and nematode assemblages on Amazonian sandy beaches for the first time. For this purpose, samples were carried out in four consecutive months encompassing a period of high visitation peak (one month Before Vacation, During Vacation, and two months After Vacation) on three contrasting beaches regarding disturbances (Urban: Atalaia; Intermediary: Farol-Velho; and Protected: Corvinas) at seven equidistant sampling stations (50 m apart) from the high tide water mark to the swash zone. At each sampling station, three biological samples and sediments samples were collected haphazardly. Also, in each station, the sediment compaction was determined using a manual penetrometer. Overall, physical sediment variables (grain size, sorting) were constant over time in all beaches, whereas differences in intensity of recreational activities and sediment compaction were found between beaches and months. Sediment compaction was considered the most important factor for the differences observed in meiofauna community structure in the study areas, and it was related to intensity of recreational activities. Variations in density and changes in richness between periods were observed in Atalaia and Farol-Velho beaches. On the other hand, Corvinas beach remained the same throughout the study. In the first month after vacation, density and richness were similar to those in the period before vacation, thus indicating that the beaches had recovered in one month. Furthermore, vulnerabilities of Tardigrada and Copepoda, as well as of the Nematoda genera Daptonema, and Chromadorita, indicate that they might be potential indicators of recreational activities.

Characterization of Intertidal Bar Morphodynamics Using a Bi-Annual LiDAR Dataset

Intertidal bars are common features on meso-and macro-tidal sandy beaches with low to moderate wave energy environments. Understanding their morphodynamics is, hence, crucial for enhancing our knowledge on beach processes which is beneficial for coastal management. However, most studies have been limited by assessing bar systems two-dimensionally and typically over the short-term. Morphology and dynamics of an intertidal bar system in a macro-tidal environment have been investigated using bi-annual LiDAR topographic surveys over a period of seven years and along 3.2 km at Groenendijk beach (Belgium). The detected bars demonstrate that a morphology of an intertidal bar is permanently on the beach. However, these individual features are dynamic and highly mobile over the course of half a year. The mean height and width of the bars were 1.1 and 82 m, respectively. The highest, steepest, and asymmetric features were found on the upper beach, while they were least developed in the lower intertidal zone. The bars were evenly distributed over the entire intertidal beach, but the largest concentration observed around the mean sea level indicated the occurrence at preferential locations. The most significant net change across the beach occurs between the mean sea level and mean-high-water neap which corroborates with the profile mobility pattern. The seasonal variability of the bar morphology is moderately related to the seasonally driven changes in storm and wave regime forcings. However, a distinct relationship may be inhibited by the complex combination of forcing-, relaxation time- and feedback-dominated response. This work conducted from bi-annual LiDAR surveys has provided an unprecedented insight into the complex spatial organization of intertidal bars as well as their variability in time from seasonal to annual scale.

Effects of a fish weir on the structure of the macrobenthic community of a tropical sandy beach on the Amazon coast

AbstractThe present study investigated the effects of a fish weir, a fixed trap used by artisanal fisheries, on the intertidal macrobenthic infauna of a macrotidal sandy beach on the Amazon coast. Biological and sediment samples were collected from within the weir and at five points of increasing distance (10 cm, 50 cm, 1 m, 2 m, 5 m and 50 m) from the external portion of the trap. The sediments from the weir and at 10 cm were dominated by mud, with a gradual decline in fine grains, water content and organic matter with increasing distance from the weir to 50 m (control). Taxon abundance and richness were significantly higher in the weir and at 10 cm than at the other sampling points. There was a trend of decreasing density and richness of the infauna from the weir to 1 m (which was a point of transition between the muddy and sandy sediments), after which the biological descriptors tended to increase once again. A shift was also observed in the dominant trophic groups, with a decrease in the abundance of the deposit feeders with increasing distance from the weir. By contrast, predators were more abundant at the points further from the weir. Our results indicate that fish weirs alter the associated sedimentary habitats, due to the increased protection from the action of waves and currents, with a micro-scale (from a few centimetres to 1–2 m) influence on the local macrofauna.

Widespread microplastics distribution at an Amazon macrotidal sandy beach

Microplastics (MPs) are widespread and cause many impacts, yet their distribution and abundance are unknown for the Amazon coast. We estimated the abundance and distribution of microplastics at a sandy beach on the northern Brazilian coast during April 2014. Sand was collected and analyzed at three depth strata (0–20, 20–40 and 40–60 cm). MPs (250–500, 501–5000 μm) from each depth were sieved and retrieved by flotation when necessary. We found 492.5 ± 556.4 particles m−3, with fibers comprising up to 95%. The abundance decreased with depth (61.5, 25 and 13.5% from the surface to 40–60 cm) and the deposition zone showed higher densities compared to the erosion zone. Although present in low to moderate abundance, MPs were widespread on the beach. The Amazon coast is an important area for fisheries and traditional communities, and further studies of its potential as a source or sink of MPs are needed.

Distribution patterns of meiofauna on a tropical macrotidal sandy beach, with special focus on nematodes (Caixa d’Água, Amazon Coast, Brazil)

Spatial distribution patterns (both horizontal and vertical) of meiofauna, with special focus on nematodes, on a tropical macrotidal beach across different climatic periods were analyzed in this study. Samplings were carried out at five stations in the intertidal zone in June (rainy season) and December (dry season), 2011. At each station, three samples were taken using a corer with 3cm diameter, which was thrust 10cm into the substrate and stratified in 0-2, 2-5, and 5-10cm. Meiofauna was comprised of 16 groups and Nematoda was the dominant. Meiofauna density during rainy season was higher at the central intertidal station and during dry season it was lower near the high tide mark, followed by an increasing trend towards the low tide mark. Meiofauna was more concentrated in the upper sediment layer during rainy season. However, during dry season, the highest density occurred in the lower sediment layer at both stations near the high tide mark. Nematoda association was comprised of 72 genera, with Daptonema and Theristus (both from the family Xyalidae) as the dominant ones in most stations and strata. The genera richness and diversity increased towards the low tide mark, with lower richness in the upper stratum at most stations. Non-selective deposit-feeders predominated during rainy season, while at dry season there was an alternation of dominance between non-selective deposit-feeders and epistrate feeders. Significant differences were found in the meiofauna community, as well as in the Nematoda association in regard to the months, stations, and sediment layers. The distribution patterns of interstitial organisms found in this study, in part, follow what is already known for microtidal beaches but other differential aspects were observed even if compared to environments of macrotidal beaches in temperate regions.

Is the vertical distribution of meiofauna similar in two contrasting microhabitats? A case study of a macrotidal sandy beach

Tides are an important forcing factor of macrotidal sandy beaches because they are directly responsible for the local morphodynamic conditions. Macrotidal beaches may harbor different microhabitats such as sandbars and runnels. We evaluated the influence of tides on the vertical distribution of meiofaunal organisms, particularly nematodes, in these two microhabitats at De Panne Beach, on the North Sea coast of Belgium. The 11 meiofaunal groups found were Acari, Amphipoda, Copepoda, Gastrotricha, Nematoda, Oligochaeta, Ostracoda, Polychaeta, Rotifera, Tardigrada and Turbellaria. The nematodes were identified to species level; the 147 species found included 112 in the sandbar and 117 in the runnel. Only turbellarians and nematodes migrated upward during low tide in the sandbar. The response of the nematodes was species-specific; during low tide, they migrated upward in the sandbar and downward toward deeper layers of the sediment in the runnel. These migration patterns were attributed to the feeding strategies in the sandbar (i.e. possible increase of diatom biomass in the surface layer due to high solar incidence), while environmental variables best explained the migration patterns in the runnel (i.e. preferred grain size and amount of total organic carbon). These results suggest a dissimilar vertical migration of the meiofauna over the tidal cycle in the two microhabitats. We attribute the vertical distribution of nematode species and some other meiofaunal groups to active migration toward preferred sites with more food or better environmental conditions. This study also indicated that other variables such as predation and competition, rather than the commonly studied physical variables should be included in future sampling designs of sandy-beach meiofauna assessments, since the environmental variables measured here could not fully explain the vertical distributions of the major meiofaunal groups or the community as a whole.

Opportunistic basal resource simplifies food web structure and functioning of a highly dynamic marine environment

Carbon flow through ecosystems is determined by the nature, availability and incorporation of basal resources (BRs) to higher trophic levels of food webs. The occurrence of abundant supplementary BR often diversifies trophic niches within food webs. Blooms of opportunistic macroalgae, which may act as additional BRs, have increased in intensity, and are expected to amplify further because of global change. Understanding the effects of high biomasses of opportunistic BRs on the functioning of naturally unvegetated coastal ecosystems is thus crucial. We set out to assess whether and how green algae (opportunistic BR) modifies macrotidal sandy beach trophic structure and functioning. We also investigated whether these effects propagate up through the web, looking at different scales and trophic levels (i.e. primary producers, specific primary consumers, and the general higher-consumer assemblage). To achieve these objectives, we used a high-resolution field sampling (over 1200 individual stable isotope-, and 180 biodiversity samples) at pristine and macroalgal-bloom-affected macrotidal sandy beaches, together with recent and novel analytical approaches (biomass-weighted isotope signatures, Isotopic Functional Indices). We found that the opportunistic BR, both directly and indirectly affects the entire beach food web across several trophic levels, by inducing shifts in trophic interactions. Overall, we found that the dominance of a BR in the form of opportunistic algae simplifies the entire food web over time. Our findings challenge the paradigm that addition of BR inherently diversifies trophic interactions within an ecosystem, and have implications for the interpretation of shifts in dynamic system food webs and eutrophicated environments.

Large-scale effects of green tides on macrotidal sandy beaches: Habitat-specific responses of zoobenthos

Sandy beaches are highly dynamic ecosystems mainly driven by physical variables, such as tidal regime. These ecosystems support numerous essential ecological functions and contain a distinctive biodiversity, but are threatened by increasing direct or indirect anthropogenic pressures, among which are green tides composed of free living Ulva spp. Studies that have been conducted to understand the effects of macroalgal mats on coastal sediment communities have mostly addressed responses in atidal or microtidal systems, and are often single-site assessments. Using large-scale field surveys across 13 macrotidal sandy beaches of two types (exposed and semi-exposed) distributed along 2700 km of coast for 7 years (REBENT program, Brittany, France), we analysed responses of zoobenthos to the presence of green tides in relation to tidal range, exposure, sediment characteristics, air and seawater temperature, precipitations, wind and salinity. Despite the high variability existing between two distinct categories of sandy habitats and also between macrotidal beaches within the study area, differences in macrofaunal community structure arose from the presence of green tides: mean abundance and species richness of macrozoobenthic invertebrates were higher where green tides occurred. Moreover, macrobenthic assemblages in the two beach-categories respond differently to eutrophication seen as green tides. Surprisingly, the effects of the presence of Ulva mats were stronger at exposed sandy beaches than at semi-exposed beaches. Our study also highlights species-specific responses: herbivorous marine invertebrates and suspension feeders were favoured by the presence of Ulva mats, whereas large sub-surface deposit feeders and bivalve drifters which surf up and down the shore with the tides were negatively affected by green tides.

Effects of macroalgal accumulations on the variability in zoobenthos of high-energy macrotidal sandy beaches

Sandy beaches, forming the most widespread coastal habitat in the world, are threat- ened by the effects of increasing anthropogenic pressure in the context of global change, includ- ing the increased occurrence of green tides composed of free-living Ulva spp. Sandy beaches are also highly dynamic ecosystems that support numerous essential ecological functions and contain a distinctive biodiversity, but their precise functioning and natural variability (i.e. the disentan- gling of biological and physical influences) remain under-studied. Our study aimed at determin- ing the effects of space, time, and environmental variables on the natural variability of macrofau- nal community structure and at specifically determining the effects of macroalgal accumulations on the observed variability. We followed a high-resolution field sampling design in space and time (261 samples) at non-vegetated and at partially and fully green-tide-impacted macrotidal sandy beaches. We used novel statistical approaches (distance-based Moran's eigenvector maps (dbMEMs) and variation partitioning) to analyse our results. The macrofaunal community struc- ture of the non-vegetated sandy beach was variable in space and time at small scales, and physical environmental variables significantly explained these variations. Our study also highlighted a decrease in this variability along a gradient of increasing coverage of stranded Ulva spp. and the increasing importance of biological variables in explaining ecological variability. Compared to a state with no Ulva, a large and homogeneous coverage of Ulva along a sandy beach shore induced a significant decrease of overall β-diversity. However, macrofaunal responses to macroalgal accu- mulation were less pronounced than what has been previously shown in micro-tidal and sheltered systems, likely due to the dynamic and unstable nature of high-energy macrotidal sandy shores.

Field experiments of beach scarp erosion during oblique wave, stormy conditions (Normandy, France)

A field-based experimental study of beach scarp morphodynamic evolution was conducted on the shoreface of a macrotidal sandy beach subject to storms combined with spring tide events (Luc-sur-Mer, France). Both video and in-situ measurements on an artificial berm are used to understand beach scarp evolution over one tide during stormy conditions. Image time stacks are used to analyze the swash action on the beach scarp and topographical data of the scarp are recorded with a terrestrial scanner laser to quantify the morphodynamic response of the beach scarp to wave action. This work provides a new and unique dataset about beach scarp changes and berm morphology in particular under rising tide and oblique wind-wave conditions. During one stormy event, the berm was completely destroyed. However, contrasting alongshore changes were measured during the erosive phase with different crest and foot scarp retreats and eroded volumes between the west and the east side of the berm. The beach in front of the scarp also shows a contrasting residual evolution, indicating an evident longshore sediment transport on the study area as a consequence of incident oblique wave conditions. A strong connection between beach evolution and beach scarp changes is clearly identified. The scarp erosion increases on the west side of the berm when the beach level is lowered and reduces when the beach surface rises on the east side. The beach slope and foreshore elevation as a result of a longshore sediment transport between east and west profiles, influence swash activity. Overall, water depth and swash activity became progressively different along the scarp during the experiment.Swash measurements indicate that the presence of the beach scarp strongly influences the swash motion. At high tide, the reflection of the uprush on the scarp front induces a collision between the reflected backwash and the following uprush dynamic. These collisions reduce and sometimes stop the motion of the following uprush, reducing the incoming swash excursion. Consequently, the scarp presence modifies the swash interaction that normally appears on a planar beach surface. With a beach scarp, the swash energy level is substantially attenuated and its spectrum is characterized by a large band. The number of uprush impacts on the scarp front calculated from video images reaches about 25 per 5min. In spite of the swash energy attenuation due to swash/swash interactions, these impacts provoke the berm destruction in about two hours. However, the onshore migration of the swash zone induced by the rising tide appears to be important to explain scarp destruction, compensating the attenuated swash activity due to backwash-uprush interactions.

Runup estimations on a macrotidal sandy beach

This paper presents a methodological approach to calculate runup from the analysis of morphodynamic conditions on a macrotidal sandy beach. The method is based on measurements of the elevation of high-tide deposits and on the analysis of morphological and hydrodynamic changes. A series of measurements has been carried out on the beach of Vougot (Brittany, France) under different wave conditions. This allowed to assess runup formula effectiveness on a macrotidal sandy beach and to determine the best slope parameters to estimate runup. The results suggest that on that macrotidal sandy beach the slope of the active section of the upper beach should be used instead of the entire slope of the foreshore, the latter resulting in an underestimation of runup elevations when used in predictive equations from the literature. Results obtained with widely used equations are relatively well correlated with observed values (r2=0.63). An analysis of the relationship between observed runup elevations and various variables has enabled the establishment of a runup estimation formula with a relatively good fit to the study site (r2=0.86).

FIELD OBSERVATIONS AND MODEL PREDICTIONS OF WAVE TRANSFORMATION ON A MACRO-TIDAL BEACH, KOREA

Macro-tidal beach processes are influenced by complicated interactions of tide actions, coastal waves and morphological changes. Tidal cycles may be a primary forcing responsible for specific characteristics of hydrodynamic and morphological processes complicated on the intertidal flat in space and time. Macro-tidal sandy beaches are frequently developed in the west coast of Korea, experiencing seasonal variations of inter-tidal processes caused by a monsoonal climate in the Yellow Sea. Large winter waves tend to excite active beach morphological processes, inducing beach erosion and seaward-directed sediment transports. This study is intended to investigate and characterize intertidal hydrodynamics including wave dynamics in a macro-tide environment in Korea, by using a numerical model named COBRAS. The measured water surface elevation data are divided into wave and tidal components, in order to be used as inputs of the model. Tidal components in terms of water level change are implemented in the model by adding constant currents at the offshore boundary. Comparisons of the measurements and the predictions show a good performance of the model for wave height transformation and wave set-up across the macro-tidal beach

Tidal exposure or microhabitats: what determines sandy‐beach nematode zonation? a case study of a macrotidal ridge‐and‐runnel sandy beach in Belgium

AbstractLately, across‐shore zonation has been found to be more important in structuring the nematode community of a tropical macrotidal sandy beach than microhabitat heterogeneity. To evaluate whether this zonation pattern applies to a temperate beach, a macrotidal ridge‐and‐runnels sandy beach in the North Sea was studied. We investigated whether a similar zonation occurs in sandbar and runnel microhabitats, and whether the runnels harbour a different community from the subtidal. Our results indicate that nematode communities from runnel and sandbar habitats are significantly different. In addition, horizontal zonation patterns for nematode communities differ between both habitats. Nematode assemblages from sandbars are divided to lower, middle and upper beach while upper and middle runnels cluster together. The subtidal and upper runnels showed dissimilar nematode assemblages, although runnels showed the same dominant species (Daptonema normandicum), which increases its abundance towards the upper runnels. This study illustrates the importance of microhabitat heterogeneity, which resulted in different zonation patterns across the sandy beach examined. The divergent zonation between sandbars and runnels in the macrotidal temperate sandy beach, compared with the pattern observed for a subtropical sandy beach with similar morphodynamics, indicates that generalizations about nematode distribution patterns should be made with caution.