Intertidal ecology Research Papers - Academia.edu (original) (raw)

Tropical coral reefs are known to exhibit high levels of biodiversity. Amphipod crustaceans are successfully adapted to a wide range of marine habitats in coral reefs, but some regions, such as the Campeche Bank in southern Gulf of Mexico, are poorly studied or even unsurveyed for amphipods. To begin to address this paucity of information, the present study records amphipod species from Isla Pérez, an island of the Alacranes Reef National Park, southern Gulf of Mexico. Twenty sites were sampled in the intertidal zone and shallow water
adjacent to the island. Thirty-one species of amphipod were identified, 15 of which represented a geographical range extension to the northern Yucatan Peninsula, with four new records for the Mexican south-east sector of the Gulf of Mexico; nine for the Gulf Coast of Mexico; and two for the entire Gulf of Mexico. Significantly, a difference in faunal composition between windward and leeward areas of the intertidal zone was found

- by and +2
- •
- Taxonomy, Coral Reefs, Marine biodiversity, Yucatan

The concentrations of Cd, Cu, Fe, Ni, Pb and Zn in the different parts of six bivalves species were determined. From the study conducted, it was found that the byssus of Perna viridis, Scpharca broughtonii and Trisidos kiyonoi; the gill of Polymesoda erosa and Donax faba; and the foot of Gelonia expansa were highly accumulative of Cu. High levels of Cd were found in the gills of Scpharca broughtonii and the byssus of Trisidos kiyonoi; and also the shells of the four remaining bivalve species. As for Zn, the mantles of P. erosa and T. kiyonoi, and the gills of D. faba, G. expansa and S. broughtonii were highly accumulative of Zn. High level of Pb and Ni were found in the shells of all the species which indicated that the shells of the bivalves were highly accumulative of Pb and Ni. Elevated levels of Fe however were found in the different parts of the bivalve since Fe is an essential metal in metabolic activities and an abundant element in nature. The heavy metals in the total tissues and the different soft tissues of the bivalves were compared with the maximum permissible limits set by five different countries. From the comparison, it was found that most of the bivalves contained metal concentrations which were below the maximum permissible limits and should pose no toxicological risk to consumers.

- by Soon -Guan Tan
- •
- Ecotoxicology, Southeast Asia, Molluscan Biology, Intertidal ecology

The development of offshore wind farms has been a way for the state to repackage national development projects using green energy discourses. In Taiwan, where the further development of nuclear power is suspended due to public antinuclear sentiment, offshore wind farms have been heavily promoted as a way of meeting electricity demand. The planned site for offshore wind farms, mainly the intertidal zone along the coast of Changhua County, overlaps with both oyster farms and the habitat of Taiwanese humpbacked dolphins, categorized as a critically endangered species by the International Union for Conservation of Nature. This has resulted in a clash between conserving the oyster farming landscape, protecting an endangered species, and developing green energy. Facing this dilemma, pro–wind farm discourses that highlight concerns about global climate change have gradually supplanted those stressing the welfare of oysters and dolphins, even though the latter have been used successfully as local icons by movements opposing previous development projects on the intertidal zone. This article reconsiders the politics of territorialization implied by the “green” label affixed to offshore wind farm projects and other forms of green energy in general. As such, the meaning of offshore wind farms, as a newly discovered energy resource, is intertwined with the changing meanings of both dolphins and oyster farms, as rival nonhuman objects of resource exploitation and natural conservation. The territorialization of such resources in the emerging discursive space of green energy has proceeded via relational placemaking with nonlinear connections among multiple human and nonhuman elements.
Key Words: conservation, intertidal zone, landscape, renewable resources, resource frontier.

- by Po-Yi Hung (洪伯邑)
- •
- Renewable Energy, Wind Energy, Space and Place, Political Ecology

Mudskippers (Gobiidae: Oxudercinae) are amphibious gobies which are “fully terrestrial for some portion of the daily cycle”. Together with the other members of the subfamily Oxudercinae, they form a diverse group of species which colonised semiterrestrial habitats in intertidal and supratidal coastal swamps. The Sundaland hotspot ecoregion hosts one of the richest oxudercine associations, including 8 genera and 17 species.

- by Gianluca Polgar
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- Intertidal ecology, Intertidal fishes, Mudskippers

The distributions of Cu, Zn, and Pb concentrations in the selected soft tissues (foot, cephalic tentacle, mantle, muscle, gill, digestive caecum, and remaining soft tissues) and shells of the mud-flat snail Telescopium telescopium were determined in snails from eight geographical sites in the south-western intertidal area of Peninsular Malaysia. Generally, the digestive caecum compared with other selected soft tissues, accumulated higher concentration of Zn (214.35714.56 mg/g dry weight), indicating that the digestive caecum has higher affinity for the essential Zn to bind to metallothionein. The shell demonstrated higher concentrations of Pb (41.2371.20 mg/g dry weight) when compared to the selected soft tissues except gill from Kuala Sg. Ayam (95.7675.32 mg/g dry weight). The use of different soft tissues also can solve the problem of defecation to reduce error in interpreting the bioavailability of heavy metals in the intertidal area. r

- by Soon -Guan Tan
- •
- Ecotoxicology, Southeast Asia, Molluscan Biology, Intertidal ecology
- by Juria T.
- •
- Climate Change, Island Studies, Marine Conservation, Coral Reefs

Physico-chemical and macrobenthic invertebrates of the intertidal zone of Gusa, Cagayan de Oro City, Philippines were assessed from March to May 2014. Water temperature, pH, salinity, dissolved oxygen, biological oxygen demand, and type of substrate were also determined in the study were within the normal range. A modified transect-quadrat method was used in an approximately 14,000 m2 of study area. Seven hundred twenty seven individuals belong to 15 species were found in the area. These organisms belong to four phyla namely: Mollusca, Arthropoda, Echinodermata, and Annelida. The three most abundant organisms found were Coenobita clypeatus, Ophiothrix longipeda, and Cypraea poraria with relative abundance of 73.86%, 4.13% and 3.71% respectively. Most of the macrobenthic fauna identified exhibited a clumped pattern of distribution, while the rest are randomly distributed. The species diversity of the area is 1.19 which is very low compared to reports from related studies.

- by Angelo Mark P Walag and +1
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- Marine Biology, Marine Ecology, Invertebrate Biology, Marine Protected Areas

Penelitian struktur komunitas makrozoobenthos pada mikroekosistem tidepool di pantai Batu Kukumbung dilakukan pada tanggal 10-17 Mei 2015. Penelitian ini bertujuan untuk mengetahui struktur komunitas makrozoobenthos, keanekaragaman makrozoobenthos, dan kondisi lingkungan yang mempengaruhinya. Penelitian ini menggunakan metode deksriptif kuantitatif, dengan pengumpulan data menggunakan metode survey. Penelitian dilakukan dengan memasang transek sepanjang 200 meter sejajar dengan garis pantai. Pada tiap tidepool yang mengenai transek garis, dilakukan pengamatan, pengukuran parameter fisika kimia perairan, serta pengambilan sampel benthos. Parameter fisik yang diukur antara lain luas tidepool, kedalaman tidepool, suhu air, suhu udara, intensitas cahaya, salinitas dan konduktivitas, sedangkan parameter kimia yang diukur yaitu pH dan kandungan oksigen terlarut (DO). Dilakukan analisis terhadap kelimpahan jenis, nilai penting, dominansi jenis, indeks kekayaan jenis, indeks keanekaragaman jenis, indeks dominansi makrozoobenthos, dan penutupan makroalga. Hasil pengukuran parameter fisik menunjukkan suhu air, intensitas cahaya, dan konduktivitas pada kategori tinggi yang dapat membahayakan kehidupan makrozoobenthos, sedangkan suhu udara, salinitas dan kedalaman perairan dalam kategori normal, sehingga mampu mendukung kehidupan makrozoobenthos. Nilai pH dan DO juga menunjukkan hasil yang sesuai dengan kehidupan makrozoobenthos. Dari analisis sampel, didapatkan 39 jenis makrozoobenthos dari 21 famili dan 6 kelas, dengan nilai kelimpahan tertinggi pada jenis Ophionereis dubia sebesar 0,51 individu/338 m2, nilai penting pada jenis Ophionereis dubia sebesar 43,97%, indeks kekayaan jenis sebesar 6,09, indeks keanekaragaman jenis sebesar 2,53, dan indeks dominansi sebesar 0,85. Penutupan makroalga didominasi oleh jenis Sargassum polycystum dengan penutupan 7,62%.

- by Aufa Aulia Kanza
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- Marine Biology, Aquatic Ecology, Marine Ecology, Biology
- by Goldin Quadros
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- Management, Mangroves, Intertidal ecology, Fishery

The remains of a timber v-shaped fishweir and associated structures have been discovered near Ashlett Creek on the tidal mudflats of Southampton Water in Hampshire, southern Britain. Radiocarbon dating of oak roundwood stakes taken from the main weir structure date it to the middle Saxon period. Clusters of as-yet undated roundwood posts within the catchment area of the weir are interpreted as the frames for fish traps that are assumed to pre- or post-date the operational period of the weir itself. The weir is contemporary with wooden v-shaped fishweirs found elsewhere in southern and central Britain, and also Ireland, but its circular catchment ‘ pound’ remains unique, in these islands, to the Solent region: it has a close parallel with another Saxon-era weir on the nearby Isle of Wight. The weir also shows striking structural similarities with examples in use today in Basse Normandy, on the southern shore of the English Channel. The paper discusses the function and operation of the weir, and places it in its social and historical context. Finally, it considers the implications of the weir’ s dating for our understanding of saltmarsh morphodynamics in this south-western part of Southampton Water, and considers in turn the implications of these dynamics for the material survival of the site.

- by John P Cooper and +3
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- Anglo-Saxon Studies, Wetlands, Marine and saltmarshes ecology, Anglo-Saxon settlement patterns (Archaeology)

In northwest Europe conflicts have routinely occurred between economic and conservation interests regarding shellfish such as cockles and mussels. The harvest of these species is economically important, but shellfish also constitute the main overwinter food supply of the oystercatcher Haematopus ostralegus. In this report we describe attempts to produced a simplified modelling approach to predict the quantities of shellfish which need to be left unharvested in order to ensure high overwinter survival of oystercatcher.
We review oystercatcher diet and prey selection in order to quantify the dependence of this species on shellfish, and determine the size ranges of shellfish which the birds consume. We also review the food requirements of oystercatchers, based on their energetic needs and the nutritional quality of shellfish. In general the data agree well with those used in previous oystercatcher modelling studies. However, there is a possibility that the daily energy requirements, calculated from an all bird allometric equation, may yield an underestimate of oystercatcher food requirements. A comparison of the physiological food requirements, i.e. the quantity directly consumed, and the ecological food requirements, i.e. the quantity required to avoid high mortality, indicated that the ecological food requirement was between 2.0 and 7.8 times greater, with the value depending on the proportion of cockles Cerastoderma edule and mussels Mytilus edulis in a site. These ratios are calculated from empirical data on oystercatcher survival and the predictions of individual-based models predicting the relationship between mortality rate and the abundance of the food supply. Data from the Burry Inlet indicated that the mean ecological food requirement was 3.3 times greater at this site.
We describe a simplified spreadsheet model, which we used to predict the food requirements of the oystercatcher population of the Burry Inlet, and thus the quantity of shellfish which must be left unharvested in order to maintain low mortality rate. The model is based on parameter values derived from the literature reviews in this study, including the energy requirements of the birds, the energy content of shellfish, the minimum size of cockles and mussels consumed, and the ratio of the ecological and physiological requirements. We describe the assumptions and limitations of the model, and compare the model with more detailed individual-based models that can be used to predict the mortality rate of shorebirds in relation to the amount of food available.

- by Kevin Wood
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- Aquatic Ecology, Natural Resources, Conservation Biology, Conservation

The sand crabs are crustaceans in Indonesian waters. The diversity of sand crabs in Indonesia is poorly understood due to the small number of studies that have been conducted. The present study revealed the diversity of Indonesian sand crabs, and assessed their phylogenetic relationships using the cytochrome c oxidase subunit 1 (CO1) and morphological characteristics. Sand crabs were collected from 14 locations spread across several sandy intertidal ranges in Sumatra (west Aceh, Padang, Bengkulu), Jawa (Pelabuhanratu, Cilacap), Bali (eastern and northern part), West Nusa Tenggara (Gili Meno Islands), Sulawesi (Tangkoko, Talise, Lero, Banggai, Buton), and southeast Maluku (the Kei Islands). Thirty-two morphological characteristics and CO1 mitochondrial deoxyribonucleic acid (mtDNA) were used to construct a phylogenetic tree. Two genera and six species were identified based on morphological characteristics. The carapace shape, antennae, and pereopods were the main characteristics that separated the Hippa and Emerita species. The CO1 marker data helped to verify the morphological data. Morphology and DNA analyses were congruent between Hippa and Emerita. H. adactyla and E. emeritus were distributed on the west coast of Sumatra and southern Java (Indian Ocean), whereas H. marmorata, H. celaeno, H. ovalis, and H. admirabilis were distributed throughout the northern and southern Pacific Ocean (Sulawesi and Kei Islands).

- by Achmad Farajallah
- •
- Marine Biology, Marine Ecology, Fisheries Science, Crustacea Decapoda

The Gulf of Cambay is a macro-tidal estuarine embayment lying in an active monsoon zone characterized by a high annual sediment load. The present study examines the distribution of foraminifera in the Narmada and Tapti estuaries of the Gulf in order to use these as analogues for the study of palaeo-macro-tidal estuarine environments and as a means of recording the extent of sea-level change in estuarine settings. Foraminifera are widely distributed in sand flats, mud flats and marshes at the mouths of the estuaries. The overall foraminiferal assemblage is low diversity, comprising epifaunal and infaunal taxa dominated by Ammonia, Murrayinella, Haynesina, Quinqueloculina, Nonion, Cibicides, Cibicidoides, Elphidium, Trochammina and Miliammina. The triserial planktonic foraminifer Gallitellia vivans, an indicator of stressed and up-welling areas, is also recorded in the intertidal sediments of the estuaries. These foraminifera are carried into estuaries up to 50 km up the river mouths by the strong tidal currents in the bay. Three biofacies are recognized: Trochammina–Miliammina biofacies (high marsh); Murrayinella-Haynesina biofacies (low marsh and mud flats) and Ammonia-Elphidium-Quinqueloculina biofacies (shallow marine).

Anadara pilula is a species in the family Arcidae, which is important economically and used widely as a food source. The cockles have a wide distribution, especially on the north coast of Java Island, Indonesia, and can be found off the coasts of Labuan, Cirebon and Gresik. Differences in the
characteristics of the coastal habitat in northern Java Island has led to morphological differences in A. pilula. This study aimed to assess differences in morphological characteristics of A. pilula from three locations on the northern coast of Java Island. Shell dimensions of 252 individuals from the three regions were measured. Simple regression analysis of shell length versus shell depth showed a difference in slope between the Gresik and Cirebon populations. One-way ANOVA and discriminant analysis were performed to compare and describe morphological differences among locations. The results showed that three morphometric characteristic significantly differed among the three populations (umbo height of right valve, symmetry of right valve and symmetry of left valve). A. pilula from the Gresik coast differred the most in morphometric characters.

- by Yusli Wardiatno
- •
- Marine Biology, Marine Ecology, Molluscan Biology, Intertidal ecology

Barnacles grow on every hard surface within Puget Sound’s intertidal zones, including on other barnacles. And
as barnacles accumulate, one upon another, often many generations deep, a rich and varied biologic community
develops around them.
Barnacle-based communities are diverse, densely populated, colorful, active, and otherwise wonderful. They
are, with respect to those attributes, comparable to coral reef ecosystems. Unlike coral reefs, there is a very real
limit to the size (depth, thickness, horizontal distribution) of barnacle aggregations.
We examine the larger of the two common Puget Sound acorn barnacles, Semibalanus cariosus, for characteristics
that may explain their critical role in these thriving communities. We also look for details that may explain the
limit to their ‘success’ as reef-builders.
In this report we look at common barnacles more closely than other observers might, but not with the formality
of professional marine biologists. We do our best to present our observations in a way that will encourage your
participation in ‘Accessible Sciences’.

- by Joseph B Small Jr
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- Marine Ecology, Ecosystem Modeling, Invertebrate Zoology, Biological Sciences

Zoanthids, the benthic Anthozoans are found in nearly all coastal marine environments. Zoanthids have become recent
interests in the field of scientific study because of the challenge they offer in their taxonomic discernment due to the
morphological variability within a species. In these study different methods has been carried out for sample preservation and
DNA extraction from Zoanthids. Sample collection and preservation in different fixatives is influential on the quality of DNA
during the extraction procedure. The present study is an effort to examine six field fixatives and tries to establish an effective
DNA extraction protocol for Anthozoans. Zoanthids were collected and preserved in fixatives like: 1) absolute ethanol, 2)
70% ethanol, 3) lyses buffer with CTAB, 4) Phosphate Buffer Saline with SDS 5) Liquid Nitrogen and 6) Dry Ice. The
genomic DNA extraction was carried out using four different protocols, viz. Lyses buffer with proteinase K (LBWPK) 2)
Lyses buffer with cetyl trimethyl ammonium bromide (LBWCTAB) 3) Lyses buffer with guanidine Isothiocyanate (LBWGIT)
4) TriZol. The most effective preservative and DNA extraction method, both in term of quality and quantity were confirmed
by Gel Analysis and purity was checked by spectrophotometric method.

- by Khushali Pandya and +1
- •
- Marine Biology, Marine Ecology, Larval ecology of marine invertebrates, Intertidal ecology

The consequences of biodiversity loss in the face of environmental change remain difficult to predict, given the complexity of interactions among species and the context-dependency of their functional roles within ecosystems. Predictions may be enhanced by studies testing how the interactive effects of species loss from different functional groups vary with important environmental drivers. On rocky shores, limpets and barnacles are recognised as key grazers and ecosystem engineers, respectively. Despite the large body of research examining the combined effects of limpet and barnacle removal, it is unclear how their relative importance varies according to wave exposure, which is a dominant force structuring intertidal communities. We tested the responses of algal communities to the removal of limpets and barnacles on three sheltered and three wave-exposed rocky shores on the north coast of Ireland. Limpet removal resulted in a relative increase in microalgal biomass on a single sheltered shore only, but led to the enhanced accumulation of ephemeral macroalgae on two sheltered shores and one exposed shore. On average, independently of wave exposure or shore, ephemeral macroalgae increased in response to limpet removal, but only when barnacles were removed. On two sheltered shores and one exposed shore, however, barnacles facilitated the establishment of fucoid macroalgae following limpet removal. Therefore, at the scale of this study, variability among individual shores was more important than wave exposure per se in determining the effect of limpet removal and its interaction with that of barnacles. Overall, these findings demonstrate that the interactive effects of losing key species from different functional groups may not vary predictably according to dominant environmental factors.

- by Rob Mrowicki
- •
- Marine Ecology, Community Ecology, Biodiversity and Ecosystem Function, Algae

Physico-chemical parameters and macrobenthic invertebrates of the intertidal zone of Gusa, Cagayan de Oro City, Philippines were assessed from March to May 2014. Water temperature, pH, salinity, dissolved oxygen, biological oxygen demand, and type of substrate were determined in the study were within the normal range. A modified transect-quadrat method was used in an approximately 14,000 m of study area. Seven hundred twenty seven individuals belonging to 15 species were found in the area. These organisms belong to four phyla namely: Mollusca, Arthropoda, Echinodermata, and Annelida. The three most abundant organisms found were Coenobita clypeatus, Ophiothrix longipeda, and Cypraea poraria with relative abundance of 73.86%, 4.13% and 3.71% respectively. Most of the macrobenthic fauna identified exhibited a clumped pattern of distribution, while the rest are randomly distributed. The species diversity of the area is 1.19 which is very low compared to reports from related studies.

- by Angelo Mark P Walag
- •
- Marine Biology, Marine Ecology, Invertebrate Biology, Marine Protected Areas

Decapod callianassid shrimps are usually solitary occupants of their burrows. They are known to show distinct sexual dimorphism of the major cheliped, which is used as a weapon for intraspecific fighting. Three species of Nihonotrypaea occur in an estuary in southern Japan; they consist of two tidal flat species (N. harmandi; N. japonica) and one boulder beach species (N. petalura), with maximum population densities of 1,400, 340, and 12 m−2, respectively. The major cheliped size and total length of shrimp were recorded from each population. The degrees of major cheliped sexual dimorphism were ordered as N. harmandi >N. japonica >N. petalura. In the laboratory, intra- and intersexual behaviors at forced encounters between two shrimps were recorded, for the former behavior throughout the year and the latter in the non-breeding season. At their intersected burrows, the shrimps either fought or retreated or filled the burrow crack. Males interacted aggressively with each other, with the intensity being N. petalura >N. harmandi ≈N. japonica. Females of the tidal flat species were non-aggressive, while those of N. petalura were as aggressive with each other as were males. Intersexually, males of all species and females of N. petalura were much less aggressive than intrasexually. In N. petalura only, burrow-sharing behavior between sexes occasionally occurred. The interspecific difference in these behaviors is in parallel with the degree of major cheliped sexual dimorphism. Different intensities of intrasexual competition for mates could have been imposed by the different population densities of these species.

- by Yusli Wardiatno
- •
- Marine Biology, Animal Behavior, Marine Ecology, Crustacean ecology

Sexual size dimorphism (SSD) implies correlated differences in energetic requirements and feeding opportunities, such that sexes will face different trade-offs in habitat selection. In seasonal migrants, this could result in a differential spatial distribution across the wintering range. To identify the ecological causes of sexual spatial segregation, we studied a sexually dimorphic shorebird, the bar-tailed godwit Limosa lapponica, in which females have a larger body and a longer bill than males. With respect to the trade-offs that these migratory shorebirds experience in their choice of wintering area, northern and colder wintering sites have the benefit of being closer to the Arctic breeding grounds. According to Bergmann's rule, the larger females should incur lower energetic costs per unit of body mass over males, helping them to winter in the cold. However, as the sexes have rather different bill lengths, differences in sex-specific wintering sites could also be due to the vertical distribution of their buried prey, that is, resource partitioning. Here, in a comparison between six main intertidal wintering areas across the entire winter range of the lapponica subspecies in northwest Europe, we show that the percentage of females between sites was not correlated with the cost of wintering, but was positively correlated with the biomass in the bottom layer and negatively with the biomass in the top layer. We conclude that resource partitioning, rather than relative expenditure advantages, best explains the differential spatial distribution of male and female bar-tailed godwits across northwest Europe.

- by Sjoerd Duijns and +2
- •
- Intertidal ecology, Ecology and Evolution

The south coast of South Africa provides the earliest evidence for Middle Stone Age (MSA) coastal resource exploitation by early Homo sapiens. In coastal archaeology worldwide, there has been a debate over the general productivity of intertidal foraging, leading to studies that directly measure productivity in some regions, but there have been no such studies in South Africa. Here we present energetic return rate estimates for intertidal foraging along the southern coast of South Africa from Blombos Cave to Pinnacle Point. Foraging experiments were conducted with Khoi-San descendants of the region, and hourly caloric return rates for experienced foragers were measured on 41 days near low tide and through three seasons over two study years. On-site return rates varied as a function of sex, tidal level, marine habitat type and weather conditions. The overall energetic return rate from the entire sample (1492 kcal h À1) equals or exceeds intertidal returns reported from other hunter-gatherer studies, as well as measured return rates for activities as diverse as hunting mammals and plant collecting. Returns are projected to be exceptionally high (~3400 kcal h À1 for men, ~1900 kcal h À1 for women) under the best combination of conditions. However, because of the monthly tidal cycle, high return foraging is only possible for about 10 days per month and for only 2e3 h on those days. These experiments suggest that while intertidal resources are attractive, women and children could not have subsisted independently, nor met all their protein-lipid needs from marine resources alone, and would have required substantial additional energy and nutrients from plant gathering and/or from males contributing game.

- by Chloe Atwater and +1
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- Human Evolution, South Africa, Intertidal ecology, Shellfish

Patchy distributions within landscapes may be caused by migration in response to different types of habitat patches. Intertidal boulder fields are landscapes in which boulders are discrete habitat patches, often with chitons attached to their under-surfaces. Chiton densities and associations with patch-edges differed between boulders overlying coarse-vs fine-sediment types, with greater densities occurring over fine-sediments. We tested if adult migration caused between-boulder distributions by measuring immigration and emigration following experimental replacement of coarse sediments with fine-sedimentå under boulders. We also assessed if the manipulations altered chiton positions relative to patch-edges, and large-scale generality was tested by including data from two continents. The manipulations did not influence the association of chitons with edges or amounts of emigration, but chitons did display positive density-dependent immigration that mirrored their distributional patterns, indicating the importance of immigration. Strikingly, all results were consistent between continents despite involving different species and even genera of chitons. By using boulder fields as a small-scale, easily manipulated landscape, we show that, even in sedentary organisms, patchy distributions within landscapes can be caused by migration alone, without the need to invoke mortality or larval recruitment.

- by C. McQuaid
- •
- Landscape Ecology, Marine Biology, Animal Behavior, Marine Ecology

Intertidal zones are one of the most studied habitats in the world. However, in Antarctica, further studies are needed for a more complete understanding of these systems. When conspicuous Antarctic intertidal communities occur, macroalgae are a key component. Given that intertidal communities have a fast response to variations in environmental conditions and could reflect climate fluctuations, we conducted a non-destructive study with photographic transects in an intertidal zone at Potter Peninsula, Isla 25 de Mayo/King George Island, over four years and during five months of the warm season. We tested the general hypothesis that macroalgal intertidal communities are mainly structured by the vertical stress gradient and that changes in temperature between seasons and between years have a great influence in the macroalgal community structure. Spatial, seasonal and inter-annual variations were studied using GLM, quantile regression and NMDS ordinations. The vertical stress gradient was the main factor that explained macroalgal cover. The Low and the Middle level shared similarities, but the latter was more variable. The High level had the lowest cover, richness and diversity. The dominant species here was the endemic red alga Pyropia endiviifolia, which is strongly adapted to extreme conditions. At the Middle level, there was a significant increase in macroalgal cover during spring months, and it stabilized in summer. Inter-annual variations showed that there is a strong variation in the total macroalgal cover and community structure over the studied years. Environmental conditions have a significant effect in shaping the studied intertidal community, which is very sensitive to climate oscillations. An increase in temperature produced a decrease of annual ice foot cover, number of snow days and - as a result - an increase in macroalgal cover. In a global climate-change scenario, a shift in species composition could also occur. Species with wide physiological tolerance that grow in warmer conditions, like Palmaria decipiens, could benefit, while other species will be discriminated. More detailed studies are necessary to predict future changes in Antarctic intertidal communities.

- by María Marcías
- •
- Community Ecology, Antarctica, Intertidal ecology, Zonation

In a coastline with growing urbanization, we examined the condition of water and sediments in sandy beaches within a gradient of uses and modification, in contrast with a reference unmodified beach, to assess different disturbance sources and environmental impact grades. The gradient was analyzed depending on beaches proximity to the urban nucleus, accessibility, tourism and recreation activities, and construction of breakwater structures. Using an integrated approach, some physical, chemical, microbiological and morphodynamic parameters were measured during two sampling campaigns. The results indicate a higher content of organic matter in sediments of the beaches near to the Veracruz Reef System with respect to the reference beach, and in the cold fronts season than in rainy season. This temporal variation can be explained by the regional pattern of surface circulation, favoring downwelling in cold fronts season and upwelling in rainy season. Water temperature, salinity and dissolved oxygen concentrations also accounted for seasonal variations. The stress gradient was evident in the granulometric characteristics of sediments, fats and oils, total solids, and enterococci concentrations in pore water. Intertidal slopes and littoral currents indicated not only a marked seasonality of these parameters, but differences between unmodified and modified beaches by breakwaters. All parameters are discussed, particularly those that accounted for the perturbation gradient, increased by the presence of breakwaters. This study serves as baseline of the environmental spatial-temporal variation in intertidal of the sandy beaches of central Veracruz, and as a reference in assessments of other beaches worldwide with similar conditions.

- by Gema Hidalgo Rodríguez and +3
- •
- Sandy Beaches, Intertidal ecology, Environmental Impact, Sandy Beaches Morphodynamic

Competition for limiting resources drives animal aggression. Aggression in hermit crabs has been well studied in shell acquisition circumstances, yet less is known about hermit crabs’ competitive behavior in other contexts, especially as they relate to feeding. As active foragers, competition for food resources may be a major determinant of hermit crab aggression and fighting behavior, particularly in intertidal marine environments, where protein-rich carrion may be limiting. Here, we measured aggressive, competitive interactions between hermit crabs
[Pagurus samuelis (Stimpson, 1857)] that were presented with carrion in the laboratory, immediately after they were collected from the field. Aggregations of three crabs were provided with either mussel or gastropod flesh. Both forms of carrion naturally indicate food availability, though only the latter may correlate with potential shell availability. We
found that levels of aggression rose significantly in response to both carrion conditions, but not in response to a control condition involving the introduction of a non-eatable object. Larger individuals displayed the highest levels of aggressive behavior, but levels of aggression did not differ between crabs provided with the gastropod and the mussel flesh. These results reveal that food—independent of a shell resource—
can be a powerful motivator for competitive behavior in hermit crabs. Further studies of food-related aggression between different hermit crab species could shed light on how interspecific competition might lead to potential specializations on different carrion or prey resources.

- by Alison L Greggor
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- Marine Biology, Intertidal ecology, Hermit crabs, Intertidal Zone

Temperate reefs are superb tractable systems for testing hypotheses in ecology and evolutionary biology. Accordingly there is a rich history of research stretching back over 100 years, which has made major contributions to general ecological and evolutionary theory as well as providing better understanding of how littoral systems work by linking pattern with process. A brief resumé of the history of temperate reef ecology is provided to celebrate this rich heritage. As a community, temperate reef ecologists generally do well designed experiments and test well formulated hypotheses. Increasingly large datasets are being collected, collated and subjected to complex meta-analyses and used for modelling. These datasets do not happen spontaneously – the burgeoning subject of macroecology is possible only because of the efforts of dedicated natural historians whether it be observing birds, butterflies, or barnacles. High-quality natural history and old-fashioned field craft enable surveys or experiments to be stratified (i.e. replicates are replicates and not a random bit of rock) and lead to the generation of more insightful hypotheses. Modern molecular approaches have led to the discovery of cryptic species and provided phylogeographical insights, but natural history is still required to identify species in the field. We advocate a blend of modern approaches with old school skills and a fondness for temperate reefs in all their splendour.

- by Nova Mieszkowska and +1
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- Time series analysis, Intertidal ecology
- by Anant Pande
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- Ecology of Coastal Systems, Intertidal ecology

The first real-time evidence of the rotation of the operculum of the trochid gastropod Phorcus lineatus has been obtained by marking the operculum of live individuals and recording the angular orientation of the operculum in relation to the apertural tooth using time-lapse microscopy. Short-term monitoring of the rotation of opercula of juvenile P. lineatus in a temperature-controlled tidal aquarium at temperatures of 15 and 19 °C gave mean rates (clockwise) of 5.6 and 7.2°/d (0.097 and 0.126 rad/d), respectively, representing a 30% increase for a 4 °C rise in temperature and a complete turn in 1.7–2.0 months. A daily phase difference of 6 h in the tidal cycle had no effect on rates. Measured rates of opercular rotation were converted to more conventional growth rates, based on weight and physical dimensions, by using biometric data from the study population. In the case of weight, close agreement between theory and direct measurement was demonstrated. Quasi-regular series of imprints of the opercular disc and peripheral striae visible on some opercula are interpreted as evidence of a discontinuous mode of growth, the features acting like the 'ticks of a clock'. The ratio of the angular separation of these features to rates of opercular rotation is in close accord with a semidiurnal rhythm. The rate of opercular rotation is recommended as a growth parameter in its own right, measurement of which is useful (especially over short periods), for elucidating in fine detail the effects of environmental factors on growth in aquaria and mesocosms and, with more difficulty , on the shore.

- by Nova Mieszkowska
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- Intertidal ecology, Mollusca

Aim To describe the distribution of biodiversity and biogeographical patterns of intertidal organisms in southern temperate and polar waters. We hypothesized that there would be differences in community structure between the Antarctic, which is most affected by ice, and the Sub-Antarctic and other neighbouring regions. We also hypothesized that rafting and West Wind Drift will be the significant drivers of biogeographical patterns. Additionally, the size, age, isolation, volcanic or glacial history of a region and the presence of large, beach dwelling, mammals and birds would all play a role in determining the level of biodiversity observed. Location South Atlantic, Indian and Pacific Oceans and the Southern Ocean. Methods We examined all available intertidal records from the Antarctic and Sub-Antarctic with additional data from neighbouring regions for comparison and context. We compiled 3902 occurrences of 1416 species of high southern latitude intertidal organisms from 229 locations and used PRIMER 6 to perform multivariate statistical analyses. Results The Antarctic and Sub-Antarctic are shown to be distinct biogeo-graphical regions, with patterns driven by a small number of widely distributed species. These wide-ranging molluscs and macroalgae dominate the biogeo-graphical structure of the Southern Ocean intertidal, most likely as a result of rafting in the Antarctic Circumpolar Current. East Antarctic intertidal habitats are potentially isolated by the Ross and Weddell Sea ice shelves but represent a great unknown in this biogeographical scheme. Main Conclusions The view that the Antarctic intertidal is a lifeless desert does not hold true, with Antarctic Peninsula intertidal communities being richer and more diverse than those in southern South America and the Sub-Antarctic islands. Changing conditions in the Antarctic and Sub-Antarctic intertidal mean that a representative baseline is needed (acquired through standardized and quantitative sampling) to assess future changes and to detect any invasive species.

- by Cath Waller
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- Biodiversity, Antarctic Ecology, Intertidal ecology, Bryozoan

Testudinalia testudinalis, the only species of intertidal limpet in the northwest Atlantic, feeds on the encrusting coralline alga Clathromorphum circumscriptum. We explored the behavior and habitat preference of this limpet in the intertidal zone of southern Maine and in laboratory experiments. We found T. testudinalis to be almost exclusively nocturnal, moving approximately 30-fold more during the night. This limpet did not home or display a consistent preference for any substrate as a resting site or preferred non-feeding habitat. However, they did show a significant preference for horizontal surfaces during feeding at night and vertical surfaces during the day. This behavior was observed at three intertidal sites along the Maine coast and in laboratory experiments, indicating a preference for a vertical resting site where heat stress, desiccation or predation may be less likely.► The limpet Testudinalia testudinalis does not home as previously suggested. ► This limpet prefers vertical resting sites near but not necessarily on encrusting coralline algae. ► Testudinalia testudinalis prefers Clathromorphum circumscriptumas a food source.

- by Joshua Lord
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- Animal Behavior, Molluscan Biology, Intertidal ecology

– Our knowledge of non-native algae in benthic estuarine habitats is relatively poor, especially compared to algal introductions along open shores or on floating structures. Gracilaria vermiculophylla is a widespread macroalgal invader in the temperate estuaries of the Northern Hemisphere, and, here, we expand its documented range within northeastern Ireland and England. Established populations occur within two inlets in the border counties, Carlingford Lough (Counties Louth and Down) and Dundrum Bay (County Down), but G. vermiculophylla is absent from open coasts between these sites. Repeated surveys in Dundrum Bay showed variable abundances, with an increase in biomass between 2013 and 2016. Three populations were discovered in England, where this species had not previously been identified: Christchurch Harbour (Dorset), Brownsea Island in Poole Harbour (Dorset), and Kingsbridge Estuary (Devon). The Irish and English thalli belong to the most common, invasive cox1 haplotype 6. Using a combination of morphological observations and 10 microsatellite loci, we found that the population at Carlingford Lough included both reproductive haploid gametophytes and diploid tetrasporophytes and genetic signatures of sexual reproduction, but the populations at Christchurch and Brownsea displayed signatures of partial clonality. Genetic diversity was higher along the south coast of England as compared

- by Nova Mieszkowska
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- Invasive species ecology, Invasive Species, Intertidal ecology

1. Tagging animals is essential to evaluate animal population dynamics and behaviour. Using unique marks requires that tags must last for the duration of the study and not affect animal behaviour and health. Echinoderms, especially smaller species, are usually considered intractable for tagging because they readily discard both internal and external tags.
2. We compared the utility of two tagging techniques for marking the small starfish Parvulastra exigua: (i) branding with a soldering iron, and (ii) injection of visible implant elastomer (VIE) of different colours. The efficiency of these techniques was evaluated by assessing (i) the effects of the tag on the mortality, growth and mobility of P. exigua; and (ii) the persistence of the tags over 30 days.
3. VIE had no detectable effect on any variable tested, whereas brand marks caused a decrease in mobility. In addition, 95% of the starfish tagged with VIE were still tagged after 1 month.
4. This technique will facilitate research on the ecology of this and other small asteroid species, and is also relevant for ecological studies of other small soft-bodied invertebrates. The combination of VIE colours plus the viability to track individuals offers a wide range of opportunities to investigate the ecology and behaviour of small invertebrates in the field.

- by Ross Coleman and +1
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- Echinoderms, Population Ecology (Biology), Behavioral Ecology, Intertidal ecology

Every spring, millions of pelagic cyprid larvae of barnacles settle in rocky intertidal habitats in Atlantic Canada, where they metamorphose into benthic recruits. These photos show barnacle recruits (Semibalanus balanoides) extensively covering the substrate of wave-exposed intertidal sites in southwestern Nova Scotia. Recruits are absent or rare, however, within circular areas centered around the attachment point of thalli of Fucus vesiculosus, a brown seaweed. As the radius of such areas is similar to the length of those thalli, such patterns might be caused by algal whiplash removing settling cyprids when those areas are exposed to wave action during high tides. However, when seeking settlement, barnacle cyprids also respond to biotic cues (e.g., predator chemicals that repel cyprids) and abiotic cues (e.g., the benthic adults' coloration that attracts cyprids). Therefore, behavioral choices may also underlie the formation of those distinctive spatial patterns of recruit density. Would cyprids respond with an avoidance behavior to the simultaneous occurrence of wave-induced water turbulence (abiotic cue) and mucus released by Fucus on the substrate (biotic cue)? The joint presence of both such cues might indicate to barnacle larvae a high risk of mortality, prompting them to settle elsewhere. This is an intriguing theory worth investigating, as it could reveal a novel combination of abiotic and biotic cues driving benthic recruitment.

- by Ricardo A Scrosati
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- Marine Biology, Marine Ecology, Marine Larval Biology & Ecology, Recruitment

Corallimorpharia is an order of marine Cnidarians. Representative of this group is commonly found in littoral and sub littoral zone with rocky substratum. This study report new occurrence and distribution range of Rhodactis cf. rhodostoma (Hemprich and Ehrenberg in Ehrenberg, 1834) (Class: Anthozoa, Order: Corallimorpharia) from coral reefs of Gulf of Kachchh and Saurashtra coast of Gujarat.

- by Khushali Pandya and +1
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- Systematics (Taxonomy), Marine Science, Intertidal ecology

This study analyzed the foraging behavior of the gastropod Nassarius pullus on garbage-impacted sandy shores of Talim Bay, Batangas, Philippines. The effect of different levels of plastic garbage cover on foraging efficiency was investigated. Controlled in situ baiting experiments were conducted to quantify aspects of foraging behavior as affected by the levels of plastic litter cover in the foraging area. The results of the study indicated that the gastropod's efficiency in locating and in moving towards a food item generally decreased as the level of plastic cover increased. Prolonged food searching time and increased self-burial in sand were highly correlated with increased plastic cover. The accuracy of orientation towards the actual position of the bait decreased significantly when the amount of plastic cover increased to 50%. These results are consistent with the significant decreases in the abundance of the gastropod observed during periods of deposition of large amounts of plastic and other debris on the shore.

- by Benjamin Sandi
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- Philippines, Molluscan Biology, Multidisciplinary, Intertidal ecology

Background: Theoretically, each species' ecological niche is phylogenetically-determined and expressed spatially as the species' range. However, environmental stress gradients may directly or indirectly decrease individual performance, such that the precise process delimiting a species range may not be revealed simply by studying abundance patterns. In the intertidal habitat the vertical ranges of marine species may be constrained by their abilities to tolerate thermal and desiccation stress, which may act directly or indirectly, the latter by limiting the availability of preferred trophic resources. Therefore, we expected individuals at greater shore heights to show greater variation in diet alongside lower indices of physiological condition.
Methods: We sampled the grazing gastropod Echinolittorina peruviana from the desert coastline of northern Chile at three shore heights, across eighteen regionally-representative shores. Stable isotope values (d13C and d15N) were extracted from E. peruviana and its putative food resources to estimate Bayesian ellipse area, carbon and nitrogen ranges and diet. Individual physiological condition was tracked by muscle % C and % N.
Results: There was an increase in isotopic variation at high shore levels, where E. peruviana's preferred resource, tide-deposited particulate organic matter (POM), appeared to decrease in dietary contribution, and was expected to be less abundant. Both muscle % C and % N of individuals decreased with height on the shore.
Discussion: Individuals at higher stress levels appear to be less discriminating in diet, likely because of abiotic forcing, which decreases both consumer mobility and the availability of a preferred resource. Abiotic stress might be expected to increase trophic variation in other selective dietary generalist species. Where this coincides with a lower physiological condition, this may be a direct factor in setting their range limit.

- by Carl J Reddin and +1
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- Marine Biology, Stable isotope ecology, Rangeland Ecology, Intertidal ecology

This study is based on the inventory of coastal benthic faunal at the level of 13 coastal sites through Oran’s coast
from Sidi Medjdoub (Mostaganem) to Sebiate (Ain Témouchent). The differences that are determined on basis of
the habitat / biodiversity shows a variation between the systems (natural, artificial, polluted, visited, and inhabited).
The difference is visible on the coastal system, which remains distant from anthropogenic pressure with an
important diversity of populations (Ain Defla, Madagh II), compared to the artificial coastal system of Oran’s
harbour dyke, or inhabited like Bousfer. This official report clearly explains the influence of hydrodynamic
functioning and the importance of human impact at different levels.

- by INNSPUB Journals
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- Biology, Biodiversity, Biodiversity Conservation, Intertidal ecology

Reproductive studies of an intertidal free-spawning population of Chiton articulatus (Mollusca: Polyplacophora) from Puerto Angel, Oaxaca, Mexico were undertaken during 2011. We used gonad histology and gonadal indices to assess the relative gonad expenditure of the sexes (RGES) and other reproductive traits, accounting for individual and seasonal variation within this population. At this location, C. articulatus is gonochoric, without sexual dimorphism, except internally by gonad colour (testis is 'salmon' coloured and ovary olive green). Annual and monthly sex ratios (m/f) do not differ significantly from 1:1. Highest population-level gonadosomatic index (GSI) corresponded to maximum (peak) ripe stage (i.e. maximum gonad investment), with a first peak in May with a high value (8.4 ± 0.5) and a second peak during August-September with a lower value (4.7 ± 0.3). GSI fluctuated throughout year implying that gonad expenditure may be seasonally constrained, but with overall synchrony between sexes of ripe and spawning stages. July to December was the main reproductive season with some facultative spawning occurring off-season. Ripe and spawning RGES did not differ between sexes, suggesting that either sperm competition is intense and/or that sperm limitation is high. Early spawning individuals may quickly replenish their gametes for a second phase of gamete release later.

- by Q Yasu Abadia Chanona and +1
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- Reproductive Biology, Intertidal ecology, Chiton, Polyplacophora
- by Ileana Ortega
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- Marine Biology, Benthic macroinvertebrates, Antarctica, Intertidal ecology

Emerita emeritus is an abundant species in Bengkulu coastal waters, but the knowledge of its reproductive biology is poor. The present study was conducted to elucidate the reproductive aspects of ovigerous female E. emeritus, including fecundity, egg volume and reproductive output. This study was conducted
between January 2015 and January 2016 in Bengkulu coastal waters, Indonesia. Samples were collected manually using shovels and hands. The results showed that ovigerous females occurred every month. Fecundity increased significantly in ovigerous females proportional to the size. No correlation was shown between sea surface temperature and egg production.
Fecundity and reproductive output decreased throughout the embryonic development.

- by Yusli Wardiatno
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- Marine Biology, Marine Ecology, Fisheries Science, Fisheries

Rocky shores are among the most-intensively studied ecosystems, however, tidal pools remain relatively understudied. This study aims to investigate the habitat use and dynamics of the shrimp species that occur in tidal pools of
a North-eastern Atlantic coast, the Portuguese coast, in particular species composition, abundance, seasonality and size
structure. Shrimps were sampled monthly from six tidal pools for one year, in the west Portuguese coast. Species diversity
was much higher than that found in previous studies, in other parts of the world. The shrimp population comprised 8
species: the European rock shrimp, Palaemon elegans, the common prawn, Palaemon serratus, the Atlantic ditch shrimp,
Palaemon varians, the Baltic prawn, Palaemon adspersus, the Oriental shrimp, Palaemon macrodactylus and the relatively
rare shrimps Eualus sollaudi, Eualus drachi and Caridion gordoni. Shrimp populations varied seasonally and among pools, with peak numbers in spring and summer. The most abundant species was P. elegans. P. elegans was present in all pools, throughout most of the year. Rare and exotic species were present mostly in spring-summer. Lower mean sizes of all shrimp were registered in the beginning of spring, most often in April or May, and gradually increased until winter. New-recruits of the most abundant species, P. elegans, generally entered the pools in spring and formed a high proportion of the population between April and August. They were responsible for the highest abundance peaks of shrimps occurring in the pools. The species richness and high numbers of juveniles occurring in tidal pools suggest that these environments may be nursery areas for coastal shrimp.

- by Catarina Vinagre
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- Marine Biology, Marine Ecology, SHRIMP, Intertidal ecology

The effects of grazing by sheep at a stocking density of c. 1 sheep ha-1 from August to April on total vegetation cover, diversity of plant species, above-ground plant biomass and concentration of crude protein, neutral-detergent fibre and acid-detergent fibre of salt-marsh vegetation was assessed over a 2-year period on a newly created salt-marsh area on the Belgian coast. Assessments were made in both grazed and ungrazed areas in four elevation zones: low, intermediate, high and floodmark zone. The cover of dominant salt-marsh species (Salicornia europaea, Limonium vulgare and Elymus athericus), plant diversity, plant biomass and chemical composition of herbage were compared between grazed and ungrazed plots, and between 2005 (initial state) and 2007 (after a 2-year grazing period) using paired t-tests. Grazing by sheep maintained plant diversity in the high zone, whereas diversity decreased in the ungrazed plots. Grazing had no apparent effect on total vegetation cover and composition of the vegetation. Concentration of crude protein in herbage increased and that of neutral-detergent fibre decreased in the high and intermediate zones. Expansion of the dominant species of the high zone, E. athericus, was not affected by the stocking density used in the study.

- by Tanja Milotic
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- Grazing and Range Management, Intertidal ecology, Grazing Ecology, Forage Quality

The feeding ecology of the brooding sea star Anasterias minuta within tide pools was examined in Central and South Patagonia. 8 470 observations of sea stars were made. A. minuta does not feed while brooding. It consumes a wide range of prey, including molluscs and crustaceans, and can be regarded as a generalist
or opportunistic predator. The purple mussel Perumytilus purpuratus was the most abundant prey item (57.6%). Other important prey were the gastropod Pareuthria plumbea, the isopod Exosphaeroma lanceolatum and the mussels Aulacomya atra atra and Mytilus edulis platensis. The proportion of sea stars feeding on sessile prey increases with sea-star size. A significant positive correlation was found between the size of the sea star and the size of the most frequent prey. The diet was fairly constant throughout the year, but diet composition differed between sites, shore level and sea-star size. The diversity of prey consumed by A. minuta was highest on the semi-exposed coast of Caleta Cordova Norte during the temperate season on the infralittoral fringe. A. minuta does not eat prey in proportion to its abundance beneath rocks within tide pools at the infralittoral fringe. Generally, the sea star consumed P. purpuratus and the gastropod P. plumbea more than other prey, even when they were not the most abundant prey present. At the midlittoral zone of the semi-exposed coast of Caleta Cordova Norte, the sea star feeds on prey species accordingly to their abundance. Larger P. purpuratus and E. lanceolatum were eaten disproportionately more often. A. minuta may have an opportunistic feeding strategy, taking unattached, wave-washed mussels when available rather that attached mussels. Consequently, it may have a variable impact on the community structure.

- by Damian Gaspar Gil
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- Marine Biology, Marine Ecology, Predator-Prey Interactions, Echinoderms

Abstract The availability of suitable microhabitats has emerged as a key requirement for maximising species diversity gains from ecological engineering of coastal habitats. This includes intertidal boulder field habitat, which is threatened by increasing urbanisation. We examined faunal use of microhabitats offered by natural intertidal boulders on two continents, South Africa and Australia, and then used artificial boulders to test possible mechanisms driving the observed patterns. Gaps often occur between the undersides of boulders and the substratum on which they lie. Substrata underneath boulders are generally uneven, so gaps can occur anywhere along the boulder undersurface, but gaps are generally larger near the edges of naturally-occurring boulders. Boulder edges were found to provide a microhabitat that had greater densities of almost all macrofauna than closer to the centre of boulder undersides. To test the model that microhabitat use of boulder edges reflects their larger gap sizes (relative to boulder centres), artificial boulders were constructed with the underside surface either flat, or with a gap underneath mimicking the mean size of the gap normally found only under boulder edges (when their average shape is considered among numerous naturally-occurring boulders). Artificial boulders were deployed intertidally for seven weeks, and macrofaunal colonisation was compared (a) between flat boulders and those with gaps, and (b) between edges and centres. Five times more macrofauna colonised boulders with artificial gaps, while no effect of proximity to edges was found when the gap-width was controlled for. The size of gaps under boulders appears to be an important microhabitat feature that can explain a widespread distributional pattern in the diverse assemblages of boulder fields. Such gaps are clearly used by numerous species, including some that are rare or commercially important. Provision and augmentation of this microhabitat should be considered for any ecological engineering project that involves intertidal or subtidal boulders.

- by C. McQuaid
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- Ecological Engineering, Marine Ecology, Biology, Benthic Ecology

This paper considers the role of macroalgae (seaweed) in the mid-19c Daguerreotype process and subsequent technical developments in chemical photography. Since antiquity, seaweed has been used as an important supplement to human well-being. Ancient medical literature recommends burnt seaweeds for the treatment of endemic goiter. Centuries later, in the mid-19th century, iodine extracted from kelp was elevated as a medical panacea. Seaweed, and the iodine it produces also has a history in the technical production of images; during the same period, the modern photographic image was born from these briny plants. In 1839 Louis Daguerre used iodine to photosensitize the earliest photographic plates, bringing into focus “the pencil of nature” (a phrase that early adopters of the Daguerreotype process used to describe their invention’s descriptive potency). This notable aspect of human technological development draws the molecular activity of the hydrosphere and complex organic organisms like macroalgae into visual culture. Its traces reveal the commonality of oceanic mediations in natural, technical, and human processes.

- by Joe Riley
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- Oceanography, Media Studies, Media Archaeology, Seaweeds