Rocky Shores Research Articles

Editorial: Arts Education in a More-Than-Human World

"Once upon a time, in a world where change danced on the horizon like leaves in the wind, there were art teachers, artist-pedagogues, artists, and art educational researchers, who read themselves into the posthumanist theories. Or maybe they engaged with the key ideas of these theories through their colleagues, or from random YouTube videos. Or maybe they ended up following the call of vital materialities, or became attracted by encounters with other-than-human species (clicks of cameras capturing fleeting moments, water droplets dotting on snow, or the whispers of limpets clinging to rocky shores). In any case, something in the world made them think differently their understandings of learning, pedagogies, art practices and research. This resulted in creative experimentation, rigorous rethinking of existing practices, and negotiating ethical responses to the messy, complex entanglements in the more-than-human worlds."

Artificial rockpools create habitat refugia on seawalls at high tide

Rockpools are fundamental habitats on natural rocky shores that provide refugia for marine life at low and high tide. Yet, artificial coastal structures lack the topographical complexity seen in these natural habitats. Eco-engineering, that may include the deployment of artificial rockpools, attempts to address the lack of suitable habitat on coastal infrastructure but most studies focus on species abundance metrics at low tide. It is important to understand how eco-engineering interventions may provide habitat at high tide compared to the surrounding artificial substrate.In this study, we demonstrate how groups of rockpools (1, 3 or 5 rockpools) add habitat complexity at high tide to a concrete seawall in Poole Harbour, UK. Between April and October 2022, eighteen GoPro cameras were deployed to record species richness and abundance in artificial rockpools and the adjacent concrete sea wall. Additionally, the length of time the most abundant fauna (the shanny fish Lipophrys pholis and the European shore crab Carcinus maenas) spent engaging in different behaviour (resting, feeding, moving) was recorded.Overall, there was no significant difference in the abundance and species richness of mobile fauna using the artificial rockpools versus the seawall. However, both the shanny and shore crab generally spent more time in the rockpools than on the seawall. Both crabs and shanny preferentially engaged in feeding behaviours on the seawall, which has been attributed to the high percentage cover of barnacle prey. Crabs and shanny spent more time resting in the rockpools than the seawall and the only reproductive behaviour observed occurred within the rockpools. Our work suggests that artificial rockpools support the habitat needs and multiple life history requirements of these species at high tide. Both the seawall and rockpools provide valuable resources, which further emphasises the need for variety in eco-engineering feature designs.

Two new species of Perinereis Kinberg, 1865 (Annelida: Nereididae) from the rocky shore of Maharashtra, India, including notes and an identification key to Group 1

Two new species of Perinereis with single bar-shaped paragnaths on area VI (Group 1) from the rocky shores of Mumbai, Maharashtra, India, are described with barely (Subgroup 1A) or largely (Subgroup 1B) expanded proximal region of dorsal ligule in posterior parapodia. Perinereis malabarensis sp. nov. can be distinguished from the morphologically similar 1B species P. euiini Park & Kim, 2017 by the paragnath count in area I, the laterally isolated paragnaths in area III, and the length of the dorsal cirrus and dorsal ligule. Additionally, P. misrai sp. nov. is more similar to 1A species P. falsovariegata Monro, 1933 and P. villalobosi Rioja, 1947, but differs by the paragnath count in areas III–V and VII–VIII, the isolated paragnaths in area III, and the number of rows in the anterior band of areas VII–VIII. The morphological characters of the current 44 species within Perinereis G1 are compared, and an identification key to the species belonging to this group is also provided.

The declining availability of wild mussel seed for aquaculture in a coastal upwelling system

A general decline in foundation species at the rocky intertidal has been observed during the last decades all around the world and primarily related to climate change. In agreement with that trend, the mussel aquaculture sector in Galicia (NW Spain), the main production area in Europe, has warned over the last years about a decline in the availability of wild mussel seed from the rocky coast. Here we compile for the first time, mussel seed collection reports by mussel farmers in Galicia for the period 2006–2021. We employed that dataset as a proxy of mussel recruitment evolution in the rocky shore for the last 16 years. Temporal analysis of our data confirmed the reported decline (-148 t yr-1), particularly pronounced from 2012 onwards. The data base also allowed us to analyze inter-annual variability according to both, climatic variations and management scenarios. Since cultivated mussels conform a meta-population with wild mussels from the rocky shore, alterations on the market preferences towards smaller individuals at harvest, could also contribute to a reduction in reproductive output. Our results show a decrease in life-time egg production under certain scenarios. Nonetheless, coastal upwelling seems to be the largest factor conditioning recruitment abundance, explaining as much as 60% of the variability observed. Decline on recruitment abundance was highly modulated by the observed increment in frequency of intense upwelling events, exceeding 500 m3 km-1 s-1 between July and November. Meridional winds also determined the spatial recruitment patterns, pointing to the large role of wind forcing on mussel larval dispersal. Our results highlights how alterations on upwelling regimes related to climate change can interact with mussel population dynamics and also condition aquaculture sustainability and food security.

Implementing biodiversity monitoring of rocky shores using photo-quadrats and Artificial Intelligence in support of data-driven decision-making of marine living resources

Implementing biodiversity monitoring of rocky shores using photo-quadrats and Artificial Intelligence in support of data-driven decision-making of marine living resources

Effects of wave exposure and habitat fragmentation on growth and grazing of rocky shore seaweeds: a mesocosm experiment

Seaweeds are foundation species on rocky shores that are exposed to a series of stressors. These include wave exposure, desiccation, grazing, and human activities, with habitat fragmentation as a common result. As part of climate and biodiversity changes, we are expecting increased winds and more frequent storm events, warmer climate, and trophic downgrading of ecosystems, causing overgrazing events. Here, we present the results from a two-factorial mesocosm experiment on the relationship between wave exposure, habitat fragmentation and growth (branching and tip elongation) of Fucus vesiculosus in the intertidal and upper subtidal. We found that intertidal seaweeds branched significantly more at low than high wave exposure. There was no effect of habitat fragmentation on branching, and no effects on tip growth from either wave exposure or habitat fragmentation. The experiment suffered greatly from uncontrolled grazing. Gastropod coverage was higher inside seaweed patches than in the seaweed free areas between and outside of the patches. In basins with highly fragmented seaweed patches, we found more gastropods at low than high wave exposure, whereas in basins with low fragmentation we found more gastropods at higher wave exposure. The percent coverage of gastropods in the basins did not seem to impact seaweed growth.

Ribbon worms (phylum Nemertea) from Bodega Bay, California: A largely undescribed diversity.

The diversity of nemerteans along the Pacific coast of the United States is regarded as well characterized, but there remain many cryptic, undescribed, and "orphan" species (those known only in their larval form). Recent sampling of nemerteans in Oregon and Washington has begun to fill in these taxonomic gaps, but nemertean diversity in California has received relatively little attention over the past 60 years. During the summers of 2019 and 2020, nemertean specimens were collected from 20 locations in the Bodega Bay region of northern California, USA, including rocky intertidal shores, sandy beaches, mudflats, and other habitats. Based on morphological assessment and DNA sequence analysis (partial Cytochrome Oxidase I and 16S rRNA genes), our surveys identified 34 nemertean species. Only 13 of these (38%) can be confidently assigned to described species. Another 11 represent species that are new to science, including members of the genera Riserius, Nipponnemertes, Poseidonemertes, Zygonemertes, Nemertellina, Oerstedia, and three species of uncertain affiliation. The remaining ten species include undescribed or cryptic species of uncertain status that have been found previously along the Pacific Coast of North America. Our surveys also document extensions of known geographic ranges for multiple species, including the first records in California of Antarctonemertesphyllospadicola, Cephalothrixhermaphroditica, and Maculauraoregonensis. This is the first report of the genus Nemertellina in the northeast Pacific and Riserius in California. Overall, our findings highlight how much remains to be learned about the diversity and distribution of nemerteans in the northeast Pacific.

Complete mitochondrial genome of the worm snail Thylacodes adamsii (Littorinimorpha: Vermetidae) from South Korea

The worm snail Thylacodes adamsii (Mörch, 1859) (Littorinimorpha: Vermetidae) is a sessile gastropod that mainly inhabits rocky shores along the warm temperate to tropical ocean. Herein, the complete mitochondrial genome (mitogenome) of T. adamsii from South Korea was characterized. The genome is 14,913 bp in length and contains 13 protein-coding genes (PCGs), 22 tRNA genes, and 2 rRNA genes. The genome organization and base composition of T. adamsii are similar to those of other vermetids. A phylogenetic tree was reconstructed using maximum likelihood based on the nucleotide sequences of the 13 PCGs; this tree supported the monophyly of Vermetidae. The complete mitogenome of T. adamsii can assist with molecular species identification and vermetid phylogenetic research in the future.

Metal bioaccumulation in marine invertebrates and risk assessment in sediments from South African coastal harbours and natural rocky shores

Industrial and urban activities are major contributors to metal contamination in coastal systems, often impacting the physiology, distribution and diversity of marine invertebrates. This study assessed metal contaminations in sediments, seawater, algae and invertebrates across four armoured systems (harbours) and two natural sites along the south coast of South Africa. Bioaccumulation factors such as Biosediment (BSAF), Biowater (BWAF), Bioaccumulation (BAF) and bioremediation of metals by invertebrate bioindicators were also determined. Spatial variation in metal concentrations were observed, however, bioaccumulation of metals was site and species-specific. Invertebrates bioaccumulated higher metal concentrations in armoured than natural sites, with filter feeders exhibiting higher concentrations than grazers. Among filter feeders, Octomeris angulosa and Crassostrea gigas bioaccumulated elevated aluminium (Al), arsenic (As), chromium (Cr), zinc (Zn) and copper (Cu), while, Perna perna accumulated elevated nickel (Ni), cadmium (Cd) and lead (Pb). Among grazers, Siphonaria serrata and Scutellastra longicosta bioaccumulated elevated Al, Cr, Cd, cobalt (Co), Cu, Ni and Zn. Bioaccumulation factors indicated that (As, Ni, Zn) were bioaccumulated by algae, and invertebrates from sediment (BSAF>1) and from seawater (BWAF>1). Additionally, invertebrates bioaccumulated metals from their prey item, algae as indicated by (BAF>1). Arsenic Cd and Pb in invertebrates were above the maximum limit set for human consumption by various regulatory bodies. Our findings underscore the significant role of coastal invertebrates in bioaccumulating and bioremediating metals, suggesting a natural mechanism for water quality enhancement, especially in urbanised coastal areas.

A synopsis of the Tanaidacea (Crustacea: Peracarida) of Singapore, with a review of tanaidacean diversity in Southeast Asia and the South China Sea

In the first comprehensive taxonomic study of the tanaidacean fauna of Singapore, a total of 23 species belonging to two suborders, three superfamilies, 13 families and 22 genera were identified from approximately 2,400 specimens, including 11 species that are possibly new to science. This material was collected from various localities in Singapore waters, from the intertidal zone to subtidal habitats up to 91 m in depth. Many species exhibited a narrow bathymetric distribution and strong affiliation to certain habitats or microhabitats such as mudflats, coral reefs, and barnacle shells on rocky shores. The Singapore Strait yielded 20 tanaidacean species, almost thrice the number of species (7) present in the Johor Straits. Three species were confined to the brackish waters in the inner parts of the Johor Straits and Sungei Pandan. Furthermore, a total of 153 tanaidacean species has now been recorded from Southeast Asia and the South China Sea. The presence of the family Numbakullidae in this region is also documented for the first time.

Variation in metabolic rate during low tide aerial exposure in the Asian shore crab Hemigrapsus sanguineus

Intertidal animals deal with physical gradients daily that create stressful conditions across the shore. These physical gradients influence the physiological performance of organisms, requiring responses that may differ with height on the shore. We examined the respiratory response to aerial exposure in the invasive Asian shore crab Hemigrapsus sanguineus during periods of low tide emersion using two field experiments. The first experiment simultaneously measured respiration of individuals collected from different heights on the shore, which had therefore been emersed for different lengths of time. The second experiment measured respiration of individuals collected at different times from the same tidal height. Respiration rates of crabs in both experiments increased immediately after emersion, nearly doubling by and peaking at ~ 1.5 h of aerial exposure, before decreasing again over the next 1.5 h. These results suggest that the energetic cost of low tide exposure is greatest shortly after emersion during the first half of the typical low tide period, but then decreases thereafter. These respiration patterns facilitate the broad intertidal distribution of this species on rocky shores throughout its range.

Relative predation intensity of an intertidal gastropod on artificial coastal defense structures.

Despite seawalls becoming ubiquitous coastal features, and having some physical similarities to natural rocky shores, it remains unclear how these urban habitats influence predator-prey interactions. Predators can affect intertidal mobile prey densities through two pathways: (1) successful predation directly influences prey mortality rates, and (2) direct and indirect effects of predation can scare and induce motile prey to seek safer areas. In this study, we investigated whether intertidal predators affect the density of the marine gastropod, Nerita undata, at four seawall sites in Singapore. Using a tethering method that we developed, we monitored the mortality and other evidence of predation (shell state) of tethered N. undata. Field experiments revealed high (22.5%-82.5%) predation potential of N. undata across the four sites, with significantly higher predation risk at lower shore heights and for snails with mixed shell coloration. Observations and analysis of the shell state after 3 days showed that predation on seawalls was primarily by crushing predators such as fish. Other predators of N. undata include predatory snails, with various feeding methods that left behind different predator signatures. Our results add substantially to the limited knowledge on predator-prey interactions on seawalls, particularly for Nerita undata, and suggest that seawall systems are more dynamic than previously thought. This further highlights the role of these artificial structures as important habitats and feeding grounds in urban coastal ecosystems.

Seabird-vectored pelagic nutrients integrated into temperate intertidal rocky shores

Seabirds provide inter-habitat connectivity by transporting vast quantities of nutrients from their pelagic feeding grounds to terrestrial and marine ecosystems via their nitrogen and phosphorous rich guano. However, it remains unclear whether seabird nutrients are cycling through many nearshore, temperate systems, such as United Kingdom (UK) rocky shores. Furthermore, it also remains unknown how seabird nutrient subsidies impact biodiversity, productivity, and recolonisation rates in UK rocky intertidal systems. Here, the impact of seabird nutrient subsidies to the Farne Islands, Northumberland, areas of high seabird densities during their breeding seasons, was compared to nearby low seabird density areas on the Northumberland coast. Estimated seabird derived nitrogen inputs and seabird densities were 420-1,025 and 949-2,279 times higher, respectively, on seabird islands than on the mainland. Seabird derived nutrient inputs led to substantially enriched nitrogen stable isotope (δ15N) values and total nitrogen content in terrestrial soil, plants, and lichen, and intertidal barnacles, and limpets, and higher δ15N values in macroalgae and turf algae. The seabird islands contained marginally greater algal species richness and higher densities of intertidal predators. However, other drivers could not be ruled out, such as nutrient inputs from mainland sources and marginally higher wave exposure at the mainland sites. No difference in limpet size, biomass, or abundance existed between the seabird islands and the mainland. On plots artificially cleared to simulate a disturbance event, barnacles recolonised faster on mainland sites. These findings provide evidence that seabird vectored pelagic nutrients are incorporated into terrestrial and intertidal ecosystems of UK islands, and therefore play an important role in facilitating ecosystem connectivity.

Probabilistic models for studying the potential spatial distribution of three intertidal decapods in the north of Chile (Taltal, 25°S, Antofagasta region)

Abstract The northern Chilean coast is characterized by its high productivity and diversity due to the presence of the cold, nutrient-rich water of the Humboldt Current. The coasts in the area are mainly bordered by rocky shores that provide many microhabitats for invertebrates. The aim of the present study was to analyse the spatial distribution of three sympatric intertidal decapods, Leptograpsus variegatus, Cyclograpsus cinereus and Petrolisthes granulosus, using probabilistic models. The studied locality was situated on the rocky shores of Taltal Bay, in the north of Chile. The counting of individuals could reveal the presence of the reported species, and if they did or did not coexist. The results revealed that L. variegatus and C. cinereus had a uniform pattern with Binomial distribition, whereas P. granulosus showed a random occurrence with Poisson distribution. These results would not coincide with classical observations of intertidal decapods on the rocky shores of continental Chile, as those denoted a gregarious pattern, but the distributions found would rather explain potential territorial behaviour.

Predation effects on benthic communities are maximized by greater taxonomic richness and diversity in Subtropical SW Atlantic

Predation effects on benthic communities are locally influenced by biological and ecological processes, such as recruitment, competition, and habitat features. We studied three Southwestern Atlantic (SWA) subtropical reef habitats (a rhodolith bed, a coral reef, and a rocky shore) to test if the predation effects on benthic communities overwhelm the habitat-context differences. We deployed panels protected and unprotected from predators on the three habitats, retrieved the panels after 45 days and quantified the recruitment of benthic sessile organisms. Despite differences in the composition of benthic assemblages, the effect of predation was mainly driven by the reduction of the ubiquitous polychaeta Spirorbidae in the three habitats. For the rhodolith bed, which supported a higher taxonomic richness and diversity than the other habitats, predation effects were higher and also driven by the reduction of other taxa. Although we recorded a greater predation effect in more diverse reefs, we attribute this result to small scale traits intrinsic to each habitat instead large-scale oceanographic patterns. Our results add pieces into the debate about how predation affects marine habitats and the importance of small-scale understanding for direct management actions in marine conservation.

Local and global stressors as major drivers of the drastic regression of brown macroalgae forests in an oceanic island

Similar to other coastal regions worldwide, forests created by brown macroalgae have severely declined in recent decades across the Macaronesian oceanic archipelagos (northeastern Atlantic), eroding the provision of ecosystem services. However, the putative effects of natural and anthropogenic stressors (both local and global) on such declines across spatial and temporal scales remain unresolved. Our research endeavored to investigate the connection between local and global stressors and the distribution and extent of the brown macroalgae Gongolaria abies-marina in the rocky intertidal and adjacent subtidal zones of Gran Canaria over the past four decades. We also quantified the presence of populations at small scales, according to local micro-habitat topography (“open rock” versus “refuge”). Through herbarium records, we additionally analyzed the historical variation in the thallus size of the species. Finally, we experimentally assessed the thermotolerance of embryonic stages to warming. The main environmental drivers explaining the regression of G.abies-marina were the increasing number of marine heatwaves, while the number of local human impacts (quantified through the HAPI index) also accounted for further regression in the extent of marine forests. Warming experimentally reduced the survival and size of macroalgal embryos. A progressive miniaturization of the species, currently restricted to micro-habitat refuges as a survival strategy, seems likely to be the final stage in the progressive disappearance of this macroalgae from the island’s rocky shores.

Influence of habitat features on the colonisation of native and non-indigenous species

Marine artificial structures provide substrates on which organisms can settle and grow. These structures facilitate establishment and spread of non-indigenous species, in part due to their distinct physical features (substrate material, movement, orientation) compared to natural habitat analogues such as rocky shores, and because following construction, they have abundant resources (space) for species to colonise. Despite the perceived importance of these habitat features, few studies have directly compared distributions of native and non-indigenous species or considered how functional identity and associated environmental preferences drive associations. We undertook a meta-analysis to investigate whether colonisation of native and non-indigenous species varies between artificial structures with features most closely resembling natural habitats (natural substrates, fixed structures, surfaces oriented upwards) and those least resembling natural habitats (artificial materials, floating structures, downfacing or vertical surfaces), or whether functional identity is the primary driver of differences. Analyses were done at global and more local (SE Australia) scales to investigate if patterns held regardless of scale. Our results suggest that functional group (i.e., algae, ascidians. barnacles, bryozoans, polychaetes) rather than species classification (i.e., native or non-indigenous) are the main drivers of differences in communities between different types of artificial structures. Specifically, there were differences in the abundance of ascidians, barnacles, and polychaetes between (1) upfacing and downfacing/vertical surfaces, and (2) floating and fixed substrates. When differences were detected, taxa were most abundant on features least resembling natural habitats. Results varied between global and SE Australian analyses, potentially due to reduced variability across studies in the SE Australian dataset. Thus, the functional group and associated preferences of the highest threat NIS in the area should be considered in design strategies (e.g., ecological engineering) to limit their establishment on newly built infrastructure.

Species contributions to ecosystem stability change with disturbance type

Simultaneous exposure to multiple stressors complicates the challenge of predicting ecological responses to global environmental change. Here, we show that the contributions of individual species and functional groups to the overall stability of ecosystems can be modified by the presence of different stressors, both individually and in combination. By disturbing natural rocky shore communities with nutrients and sediments and simulating extinction of predatory whelks and grazers, we also found that consumers can simultaneously stabilise and destabilise communities along different stability dimensions, irrespective of their trophic position. Our results suggest that our experimental disturbances influenced consumer contributions to stability indirectly by modifying the interactions between consumers and macroalgae in different ways. These findings merit further exploration in different systems exposed to a range of different stressors to better understand how perturbations of different kinds can modify the multifaceted contributions of species to the overall stability of ecosystems.

Does the incorporation of shell waste from aquaculture in the construction of marine facilities affect the structure of the marine sessile community?

The growth of the human population causes significant harm to ecosystems, directly affecting the biological diversity of coastal areas by replacing natural habitats with artificial structures such as breakwaters, ports, and marinas. The hard substrate from those marine facilities lacks the topographic complexity of natural habitats. Because of that, artificial habitats usually do not support a diverse community to the same extent as rocky shores in the surroundings. To address this issue and bring a strategic solution to the improper disposal of shell waste from aquaculture farms, we evaluated how increasing the environmental heterogeneity of walls by incorporating mussel and oyster shells on artificial concrete affected the diversity of sessile organisms from the subtidal zone. Adding shells to concrete positively affected ascidians' richness. Substrates with added shells supported more species than flat substrates in total. They promoted species that did not occur on flat substrates that simulated the traditional walls of marinas and harbors. However, it did not affect the number of bryozoans and the average species richness. Consequently, incorporating shells resulted in communities with completely distinct structures from those on flat substrates. Adding shells affected the community structure, reducing the dominance by the exotic bryozoan Schizoporella errata, and promoting the occurrence of other groups, such as ascidians. Using shell residues from aquaculture on marina walls adds substrate for colonization. Still, it is also likely to provide refuges for fragile and vulnerable organisms, like crevices and pits in natural habitats. Because of that, the increment in diversity was mostly group-specific and restricted to ascidians. This research reinforces the importance of creating complex artificial coastal structures, inspired by the blue economy, for a more heterogeneous coverage of sessile communities and reduced presence and dominance of exotic species. Thus, the strategy tested here, besides the effects on the sessile community, also supports efforts to reduce inappropriate waste disposal in the environment.

The role of food value on host use by the herbivorous amphipod Sunamphitoe pelagica

Mesograzers often use macrophytes as both food and habitat and may have strong effects on primary producers. In this context, understanding the factors mediating their interaction with macrophytes, such as host food value, is an important step to predict the impacts of these herbivores on aquatic ecosystems. The amphipod Sunamphitoe pelagica is a mesograzer with distribution restricted to a few brown macroalgal hosts, however it is unclear if food value drives host use by this mesograzer. Herein, we investigated the distribution of S. pelagica and the food value of its hosts. For that, the abundance of S. pelagica on the macroalgae Sargassum filipendula, Padina gymnospora, and Dichotomaria marginata was evaluated seasonally in a subtidal rocky shore at Fortaleza Beach (23°32′S, 45°10′W), state of São Paulo, Brazil. Furthermore, we conducted laboratory experiments to test feeding preference and rate, as well as the performance (e.g. survival, growth, and reproductive potential) of S. pelagica using the same macroalgal hosts used in the field abundance investigation. Overall, the mesograzer was more abundant on the brown macroalgae Sargassum and Padina than on the red macroalga Dichotomaria. In both feeding preference and rate experiments, S. pelagica consumed more Sargassum and Padina than Dichotomaria. Moreover, the consumption of Padina and Sargassum resulted in high performance of this mesograzer, while juveniles raised on Dichotomaria had a low survival, perishing within few days of experiment. These results suggest the host use by S. pelagica is strongly driven by the food value of macroalgal hosts and are in accordance with the narrow host breadth of this mesograzer. Therefore, considering the vulnerability of large macroalgae to climate change and habitat alterations, the restricted host use by S. pelagica to few brown macroalgae may increase its risk of local extinction.