Intertidal Rock Platform Research Articles

Temperate Intertidal Ecosystems are Functionally Richer but More Vulnerable to Loss Than Tropical Ecosystems.

Gastropods are major contributors to a range of key ecosystem services on intertidal rock platforms, supporting trophic structure in both terrestrial and marine contexts and manipulating habitat complexity. However, the functional structure of these assemblages is rarely examined across broad spatial scales. Here, we describe patterns in gastropod functional diversity, redundancy and vulnerability to functional loss across a latitudinal gradient following the west coast of Australia (18° S-34° S). Specifically, we created a trait matrix based on six categorical traits for 186 gastropod species from 39 sites to examine how trait composition varied with latitude. We found there was no latitudinal gradient in either functional richness or distinctiveness despite clear gradients in species richness and taxonomic distinctiveness, which both increased towards the equator. We delineated two distinct functional bioregions, a temperate south (34° S-27° S) and a tropical north (24° S-18° S), and found that the temperate bioregion had greater functional richness and uniqueness but lower redundancy compared to the tropical bioregion. Our findings show that gastropod assemblages in the temperate bioregion are more vulnerable to functional loss as their functional entities are supported by fewer or even single species. Comparatively, the tropical bioregion reported higher redundancies, which could provide a buffer against future change. Understanding the functional structure of intertidal ecosystems is vital as gastropods face the uncertain impacts of coastal tropicalisation, range shifts and sea level rise.

Population connectivity across east Australia's bioregions and larval duration of the range‐extending sea starMeridiastra calcar

AbstractThe diversity and distribution of marine species in eastern Australia is influenced by one of the world's strongest western boundary currents, the East Australia Current, which propels water and propagules poleward, a flow intensifying due to climate change.Population genetic structure of the asterinid sea starMeridiastra calcarwas investigated across its range in eastern Australia (12° of latitude, 2,500 km) from northern New South Wales to its poleward‐extending range in Tasmania at the southern edge influence of the East Australia Current.Population structure and connectivity ofM. calcarwere examined across six bioregions using six microsatellite loci (nuclear DNA) and the control region (mitochondrial DNA). The potential influence of the extent ofM. calcar's intertidal rock platform habitat was also assessed.Genetic structure analysis indicated that the Hawkesbury Shelf contained distinct genetic clusters, whereas the two sites in the Batemans Shelf differed from each other, with Jervis Bay Marine Park having just one genetic cluster. The Manning Shelf, Twofold Shelf, and Bruny bioregions all had similar genetic composition.Strong self‐seeding (68–98%) was indicated by microsatellite loci for all bioregions, with lower (0.3–6.5%) migration between bioregions. Poleward (New South Wales to Tasmania) migration was low except from the Manning Shelf (30%).Contemporary population connectivity and genetic structure ofM. calcarappear to be influenced by ocean currents, habitat distribution, and its short planktonic larval duration, which was a minimum of 12–14 days, depending on availability of a settlement cue.The dominance of unique genetic groups in the Hawkesbury bioregion shows the importance of this region forM. calcarand possibly a diversity of co‐distributed rock platform species. This highlights how important it is to have a large marine park in the Hawkesbury bioregion, which is presently lacking.

Does topography of rocky intertidal habitat affect aggregation of cerithiid gastropods and co-occurring macroinvertebrates?

Species aggregation has important implications for population survivorship and ecological functioning in many habitats, including rocky intertidal shores, which have been valuable to research for understanding ecological patterns and process. Intertidal gastropods of the family Cerithiidae often form extensive aggregations for which the driving mechanism may be positive thigmotaxis, i.e. movement occurring until an obstructing surface is contacted, then cessation of movement. However, it is unknown if thigmotaxis may occur by cerithiids contacting and aggregating around uneven surfaces of the rock topography, or by contacting other conspecific individuals. We quantified aggregation patterns in invertebrate assemblages and topographic complexity at intertidal rock platforms in NW India with extensive cerithiid populations. The cerithiids Clypeomorus moniliferus and Cerithium caeruleum were the most common species. Distribution analysis confirmed significant over-dispersion indicative of aggregation (densities were often around zero but occasionally reached up to 680 dm−2). Multivariate correlation analyses showed that topographic complexity contributes to overall species assemblage variability, but there was no evidence that topographic complexity correlates with cerithiid abundances or was likely to affect their aggregation. Thus the thigmotaxis producing cerithiid aggregation is probably associated with individuals contacting each other rather than any feature of the rock surface such as crevices or raised areas. Overall, while some components of species assemblages were associated with complex topography, regarding the abundant cerithiids, potential population benefits from aggregation (e.g. reduced desiccation and temperature) may be expected on rocky shores with any level of topographic complexity.

Learning together: developing collaborative monitoring of intertidal invertebrates in the Karajarri IPA, north‐western Australia

SummaryThe Karajarri Indigenous Protected Area, in the south‐west Kimberley, is home to vast intertidal rock platforms that form a culturally and ecologically important environment for Karajarri Traditional Owners and wider Bidyadanga community. Karajarri Rangers initiated a collaborative partnership with researchers to devise an intertidal invertebrate monitoring protocol to meet the requirements of their Healthy Country Plan and sustainably manage their cultural harvesting. The project aimed to design and trial a monitoring protocol that blended Indigenous ecological knowledge and values with western scientific rigour. To investigate and document the community’s ecological knowledge of marine resources, a series of Ranger interviews, focus groups and collaborative fieldwork was conducted. Data collected from these qualitative methods provided valuable insights into knowledge of the intertidal environment and fauna and the community’s management aspirations and priorities. Informed by these data, a monitoring protocol was cross‐culturally designed to combine Indigenous knowledge and values within a western scientific framework. Two methodologies were piloted, focusing on a small subset of culturally significant target species. Although both were successful, the trial indicated that Rangers preferred abundance‐focused methods for ecological monitoring. Further refinement of the monitoring protocol is required to build western science knowledge of the ecosystem and meet Ranger management goals. However, this study provided the basis of future monitoring strategies for Karajarri Rangers, formed a lasting collaborative partnership and is a useful exploration of Indigenous preferred approaches to western scientific monitoring of intertidal rock platforms.

Chaunopyran A: Co-Cultivation of Marine Mollusk-Derived Fungi Activates a Rare Class of 2-Alkenyl-Tetrahydropyran

Co-cultivation of Chaunopycnis sp. (CMB-MF028) and Trichoderma hamatum (CMB-MF030), fungal strains co-isolated from the inner tissue of an intertidal rock platform mollusc (Siphonaria sp), resulted in transcriptional activation of a rare class of 2-alkenyl-tetrahydropyran, chaunopyran A (7), and biotransformation and deactivation of the antifungal pyridoxatin (1), to methyl-pyridoxatin (8). This study illustrates the complexity of offensive and counter-offensive molecular defenses encountered during fungal co-cultivation, and the opportunities for activating new, otherwise transcriptionally silent secondary metabolites.

Molluscan death assemblages from uplifted Holocene terraces, Mahia Peninsula, New Zealand, interpreted from present-day intertidal ecology

Beu, A.G., August 2016. Molluscan death assemblages from uplifted Holocene terraces, Mahia Peninsula, New Zealand, interpreted from present-day intertidal ecology. Alcheringa 41, xxx–xxx. ISSN 0311-5518.Macrofossils from cover beds of marine terraces at Table Cape, Mahia Peninsula, uplifted coseismically ca 250, 1400, 1850 and 3500 years ago are compared with the fauna living on the nearby 200-m-wide intertidal rock platform. The inner platform is dry at low tide, apart from shallow pools containing Diloma aethiops and abundant but unexpected specimens of Zeacumantus subcarinatus and Cominella glandiformis exposed to the sun; all are common fossils in the terrace cover beds. The outer platform is carpeted densely with the alga Hormosira and shelters a diverse fauna, again all common fossils in the terrace cover beds. Sand and gravel containing shell fragments and supporting Zostera sea-grass turf unexpectedly covers ca 5% of the platform in low areas along the east coast. The fossil fauna is listed from 47 samples from two trenches excavated east–west and north–south through the terrace cover beds. Death assemblages of 158 molluscs, including 24 new records as fossils, and 11 taxa in other phyla delimit sediment derived from four shell accumulation sites identified around the present cape: storm beach, high-tidal strand line, hollows in the rock platform and Zostera flats. Up to 32 of the 47 samples (68%) possibly were deposited in Zostera flats; the rest were sand beach accumulations deposited at and near the high-tidal strand line. All fossils common in the cover beds lived on the rock platform. Differences between the deposits in the two trenches result from two factors. Protection along the east coast by protruding tephra beds and an outer rampart armoured with the macroalga Durvillaea prevented erosion of Zostera-supporting sediment which, therefore, was retained after each uplift event. The exposed eastern position of Table Cape also caused sediment to be transported predominantly westwards, onshore on the east coast but away from Table Cape along the north coast.A.G. Beu [a.beu@gns.cri.nz], Paleontology Department, GNS Science, PO Box 30368, Lower Hutt 5040, New Zealand.

Desiccation stress in two intertidal beachrock biofilms

Chlorophyll a fluorescence was used to look at the effect of desiccation on the photophysiology in two beachrock microbial biofilms from the intertidal rock platform of Heron Island, Australia. The photophysiological response to desiccation differed between the beachrock microbial communities. The black biofilm from the upper shoreline, dominated by Calothrix sp., showed a response typical of desiccation-tolerant cyanobacteria, where photosynthesis closed down during air exposure with a rapid and complete recovery upon rehydration. In contrast, the pink biofilm from the mid-intertidal zone, dominated by Blennothrix sp., showed no distinct response to desiccation stress and instead maintained reduced photosynthesis throughout drying and re-wetting cycles. Spatial differences in photosynthetic activity within the black biofilm were evident with a faster recovery rate of photosynthesis in the surface cyanobacteria than in the deeper layers of the biofilm. There was no variation with depth in the pink biofilm. The photophysiological differences in desiccation responses between the beachrock biofilms exemplify the ecological niche specialisation of these complex microbial communities, where the functional differences help to explain their vertical distribution on the intertidal shoreline.

LOW-COST, ULTRA-HIGH SPATIAL AND TEMPORAL RESOLUTION MAPPING OF INTERTIDAL ROCK PLATFORMS

Abstract. Intertidal ecosystems have primarily been studied using field-based sampling; remote sensing offers the ability to collect data over large areas in a snapshot of time which could compliment field-based sampling methods by extrapolating them into the wider spatial and temporal context. Conventional remote sensing tools (such as satellite and aircraft imaging) provide data at relatively course, sub-meter resolutions or with limited temporal resolutions and relatively high costs for small-scale environmental science and ecology studies. In this paper, we describe a low-cost, kite-based imaging system and photogrammetric pipeline that was developed for constructing highresolution, 3D, photo-realistic terrain models of intertidal rocky shores. The processing pipeline uses automatic image feature detection and matching, structure-from-motion and photo-textured terrain surface reconstruction algorithms that require minimal human input and only a small number of ground control points and allow the use of cheap, consumer-grade digital cameras. The resulting maps combine colour and topographic information at sub-centimeter resolutions over an area of approximately 100m, thus enabling spatial properties of the intertidal environment to be determined across a hierarchy of spatial scales. Results of the system are presented for an intertidal rock platform at Cape Banks, Sydney, Australia. Potential uses of this technique include mapping of plant (micro- and macro-algae) and animal (e.g. gastropods) assemblages at multiple spatial and temporal scales.

Consequences of realistic patterns of biodiversity loss: an experimental test from the intertidal zone

Studies of the effects of biodiversity on ecosystem function (BDEF) have largely found positive, saturating relationships. However, these studies have been criticised for generating species loss randomly when real extinctions are strongly biased toward rare species. We investigated BDEF relationships in the mollusc fauna of an intertidal rock platform at Griffiths Point, San Remo, south-east Victoria, Australia. Field surveys found that areas with the lowest function (mollusc biomass) were associated with lowest diversity. Excluding individual species from experimental enclosures affected function differentially depending on species’ initial abundance. Rectangular enclosures were attached to the rock platform enabling molluscs to be enclosed while allowing sea water to flow through. Removal of the most abundant species had a positive effect on mollusc biomass, suggesting an inhibition of the other species in the community. In the absence of the most common species, the less abundant species were more productive in combination than when present singly. Taken collectively, these results provide evidence for a relationship between biodiversity and ecosystem function which is a product of both diversity per se and species identity.

Morphodynamic Characteristics and Short-Term Evolution of a Coastal Sector in SW Spain: Implications for Coastal Erosion Management

Abstract In SW Spain, numerous tourist beaches have been nourished over recent years to counteract coastal retreat. Nourishment projects have not produced great endurance, mainly because of the lack of basic information on coastal dynamics and longshore sediment transport paths. In order to cover these aspects in a sandy coastal sector south of the Guadalquivir River mouth, a beach monitoring program was carried out between 1996 and 1998, with a secondary program between 2000 and 2002. Four main beach types were identified, each one with different volumetric trends during the monitoring periods. Most beaches recorded accretion because of the prevalence of fair weather conditions, which emphasized differences among beaches. In a broad sense, beaches located on intertidal rock platforms recorded erosion or no change. Those located updrift of rock platforms or human-made constructions (groins) recorded accretion. These structures divide the coast into several littoral cells, which control longshore sediment ...

Recreational Use of a Marine Protected Area: Point Lonsdale, Victoria

This article reports findings from observational and questionnaire surveys of visitors to a Marine Protected Area (MPA) at Point Lonsdale, Victoria. The MPA was established primarily to protect the biodiversity of intertidal rock platforms, with only limited restrictions being placed on fishing. Visitor surveys were undertaken to identify and quantify recreational uses, assess level of compliance with regulations, identify the uses most likely to have damaging impacts on biota, and to assess awareness of, and support for, this MPA and for MPAs in general. A questionnaire survey of visitors supported observational survey findings concerning recreational use patterns and provided information on awareness about and attitudes towards conservation measures for this location and for Victoria's marine environment. The finding that about half the visitors were not aware that they were visiting a marine protected area has implications for future management of this area and MPAs in general. Most visitors indicated support for the concept of marine conservation areas and marine protected areas.

How many juvenile abalone are there? The example of Haliotis roei

We use population surveys of Haliotis roei on intertidal rock platforms at Perth, Western Australia to examine recruitment of juvenile individuals into the adult, fishable population. Despite intensive surveys conducted seasonally and over several years very few small H. roei were found. We propose the following life cycle for Haliotis roei: juveniles grow fast, reach adult size quickly, and survive for a number of years as adults. Recruitment of juveniles to the adult population is low, either through a steady annual maturation of juveniles or by substantial recruitment during an occasional good year.

Limited effects of the sea urchin Echinometra mathaei (de Blainville) on the recruitment of benthic algae and macroinvertebrates into intertidal rock platforms at Rottnest Island, Western Australia

The sea urchin Echinometra mathaei occurs at densities of up to 100 per m 2 on intertidal rock platforms at Rottnest Island, Western Australia. Contrary to expectation, the experimental removal of these urchins from urchin-dominated areas at two sites on the Island produced little evidence to suggest that the presence of E. mathaei was either necessary for or specifically preventing the recruitment of any particular species of macroalga or macroinvertebrate. At Cape Vlamingh where urchins grazed extensively, removal of urchins was followed by a large increase in the cover of non-encrusting algae, which were the same species that occurred in lesser numbers in uncleared plots. At Radar Reef, where grazing was confined to the urchins' individual burrows, removal of urchins had little effect on the cover of the algae. Furthermore, there was no “keystone” effect of urchins on the algal composition at either site, as domination of the understorey by canopy species was prevented by the physical conditions at Radar Reef and the failure of the canopy species to recruit at Cape Vlamingh. The number of recruits of all species of macroinvertebrates was low (<10 per m 2), and there was no difference in the identity of the species that recruited into the cleared and uncleared plots at either site, although the presence of urchins did have an effect on the abundance and spatial distribution of recruits of conspecifics and the limpet Siphonaria zelandica, and on the distribution of adults of the mobile gastropod Turbo intercostalis. With such a limited effect on recruitment, E. mathaei is much less of a controlling factor in this intertidal community than has been reported for other species of sea urchins in subtidal communities. Processes affecting the supply of propagules to these platforms appear to be the more important determinants of community membership and structure.

A Novel Brominated Lipid from an Australian Cyanobacterium, Lyngbya sp.

A Lyngbya sp. collected from intertidal rock platforms at Point Lonsdale, Victoria, Australia, has been found to contain the novel secondary [(1'Z)-3'-acetoxy-2'-bromo-1'-prop-1'-enyl]-2,5-dimethyldodecanoate [1]. The structure of 1 was determined by spectroscopic analysis and degradation.

Late Quaternary movement of Aspy Fault, Nova Scotia

An emerged Sangamonian (125 ka) intertidal rock platform at +7 m asl is apparently upthrown to +22 m asl along Aspy Fault on Cape Breton Island. The 15 m displacement may be an isostatic response to rapid ice retreat or erosional unloading, or it may be a tectonic effect due to release of crustal stress stored during Wisconsinan glacier cover.

High-energy, inner shelf carbonate facies along a tide-dominated non-rimmed margin, northwestern Australia

High-energy, inner shelf carbonates occur within 1 to 2 km of the mainland along the southern part of the Northwest Shelf (a non-rimmed carbonate shelf) along northwestern Australia. Coarse-grained sands and gravels are deposited on and adjacent to a chain of subtidal and intertidal rock platforms which lies oblique to regional NE-SW directed tidal currents. Intertidal and subtidal sand sheets, less than 50 cm thick, predominate along the margins and interior of the chain, and subtidal linear to sinuous sand bodies up to 10 m thick and 4 km in length form banner banks to the northeast of rock platforms and reefs. Other features include narrow fringing and patch coral reefs, calcareous red-algal reefs, and intertidal through subtidal coral shingle ridges. Fleshy algae are abundant on open, sand-covered and bare rock platforms as well as forming a mantle on relict coral reef frameworks. Supratidal through subtidal sediments are comprised of skeletal (molluscs, foraminifera, bryozoans, corals, calcareous red algae) and rock fragments, the latter derived from rock platforms; calcareous chlorophytes (e.g. Penicillus and Halimeda) are not important sediment contributors. In general, sediments are not representative of the present-day turbid and fleshy algal-dominated subtidal environment. The predominantly coarse-grained lithofacies (<3 wt.% mud) and configuration of sand bodies are controlled by (1) vigorous tidal currents (up to 170 cm s −1) established via unimpeded across-shelf transport of oceanic waters, in the absence of a shelf margin rim, and tide ranges of 2–4 m; (2) interaction of shelf waters with rock platforms and reefs along the inner shelf creating strong currents; (3) passing cyclones; and (4) sediment reworking within normal strong wind, tide and wave regimes. High-energy carbonate sand shoals along this tide-dominated inner shelf are far removed from the shelf-slope break, facies distribution being similar to nearshore facies of a distally steepened carbonate ramp.

Pre-Late Devensian coastal rock platforms around Dunbar

Wave–cut rock platforms which predate the last glaciation are increasingly recognised around the coast of Scotland (Walton 1959; Dawson 1980; Sissons 1981; Gray 1985; Browne and McMillan 1984). This paper reports new evidence from the Dunbar area where coastal rock platforms between 0 and 25 m OD are locally overlain by till and so must also predate the Late Devensian glaciation. Coastal rock platforms in the Dunbar area (Fig. 1a and 1b) comprise at least four groups: 1: High Raised Rock Platforms. This group includes platforms which lie at elevations of between 16 and 25 m OD. Typically, these are covered by till and can be traced at intervals from North Berwick to Berwick-on-Tweed. Good examples of High Raised Rock Platforms occur near Tantallon Castle [Nat. Grid Ref. NT 59 85], east of North Berwick, at Cove [NT 78 71], and at Dunbar [NT 66 79], where a crag-and-tail rises from the platform (Sissons 1967) (Fig. 2). 2: Raised Rock Platform. The front edge of this platform lies between 2 and 4 m OD and is found at intervals along much of the coastline between Aberlady and Torness. The Raised Rock Platform reaches widths of at least 250 m and is separated by a small rock cliff or ramp from the Intertidal Rock Platform. The Raised Rock Platform is overlain by littoral deposits of the Main Postglacial Raised Shoreline formed at c. 6,500 BP (Smith 1972; Sissons 1976). 3: Inter-Tidal Rock Platform. A well-developed rock platform exists around present sea . . .

Population characteristics of the gastropod Cantharidus pulcherrimus on intertidal platforms in the Perth area of Western Australia

Abstract The trochid gastropod Cantharidus pulcherrimus is shown to be abundant on intertidal rock platforms in the Perth metropolitan area of Western Australia, where it is concentrated in the Sargassum algal zone. In this zone C. pulcherrimus is found living on macroalgae rather than the underlying rock. Density of snails varies seasonally, with maximum density occurring in summer and minimum density in autumn. Recruitment of juveniles into the population occurs during the winter (June-August). The young snails grow rapidly and spawn at one year of age in March or April. A small proportion of the adults survives for a second year. Loss of snails as macroalgae are washed from the platform by winter storms is the largest known source of mortality. The life history strategy of C. pulcherrimus is discussed in relation to that of other trochids.

Variations in the density and variety of intertidal epilithic microflora

In order to investigate seasonal changes in the density and variety of the microfloral assemblage, samples were collected from an intertidal rock platform near Sydney, Australia, by brushing the rock surface with a toothbrush. A large number of samples was obtained from the natural sandstone substratum at different levels on the shore and at different sites. The assemblage was dominated by a blue-green alga, Anacystis sp., a situation not previously described in any similar system. Also present were diatoms and vanous red, green and brown algal sporelings. Density of cells in the assemblage was greatest in winter, whereas variety was greatest in summer Both density and vanety were greater lower on the shore and at more wave-exposed sites. These patterns differ from those reported by other studies perhaps because the site is different in terms of its weather and its community of grazing gastropods.

Marine bivalve bores above present high tide level in a limestone cliff near Ord, southern Skye

Bores of marine molluscs above high water mark have been used as evidence for former higher than present sea levels, for instance in the Mediterranean ([Zeuner 1945][1], p. 229). In Scotland, empty bores attributed to the marine bivalve Hiatella arctica (Linne) have been reported up to 2 m above high tide level in limestone at Seafield Point, Loch Kishorn (Fig. 1) by Smith ([1978][2]). She also recorded the presence of the living animal near low water level at this locality. The bores described below were discovered during the field meeting of the Edinburgh Geological Society held in the western Highlands and Skye in May 1984. The foreshore and cliff immediately north of the mouth of the Ord River at Ord (Fig. 1) are formed of cherty dolomitic limestones of the Sailmhor and Eilean Dubh formations of the Lower Palaeozoic Durness Group ([Peach et al. 1910][3]). There is an intertidal rock platform up to 200 m wide which bears traces of moutonee-like forms. These suggest that the platform was glaciated and was therefore cut prior to the last ice movement across the area. The intertidal platform is separated from the base of the cliff by a gently sloping ramp and a poorly developed higher platform. The angle between the latter and the base of the cliff is at a height of c 1 m above high water as indicated by the distribution of black and yellow lichens, seaweeds and land plants. In the intertidal zone the bedrock and limestone boulders lying on . . . [1]: #ref-10 [2]: #ref-6 [3]: #ref-4