A physically derived exposure index for marine shorelines

Thomas, M. L. H.

doi:10.1080/00785326.1986.10429719

Cited by 65 publications

(50 citation statements)

References 30 publications

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“…The percentage organic content of the sediment was determined using the Walkley and Black titration method following wetoxidation by potassium dichromate, as described by Buchanan (1984) and Morgans (1956). The physically derived exposure index proposed by Thomas (1986) was used to determine the exposure to wave action experienced by each beach. The length of the beaches studied was determined from survey sheets.…”

Section: Methodsmentioning

confidence: 99%

Low faunal diversity on Maltese sandy beaches: fact or artefact?

Deidun

Azzopardi

Saliba

et al. 2003

Estuarine, Coastal and Shelf Science

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Eight sandy beaches on Malta and two on Gozo were sampled for macrofauna to test the hypothesis that Maltese beaches have an intrinsically low diversity. Stations distributed in the supralittoral (dry zone), mediolittoral (wet zone) and upper infralittoral (submerged zone to 1 m water depth) were sampled by sieving core samples and standardised searching during daytime, and pitfall trapping and standardised sweeping of the water column using a hand-net at night, as appropriate. Physical parameters of the sediment were measured and human occupancy of the beaches was estimated.From the supralittoral and mediolittoral, 39 species represented by 1584 individuals were collected by the combined techniques of pitfall trapping, sieving and standard searching. For Ramla beach, which had the highest diversity, 267 individuals representing 25 infaunal species were collected by sieving from a combined volume of 1.175 m 3 of sand, and 149 individuals representing 28 epifaunal species were collected by standardised searching from a combined area of 700 m 2 of sand during two winter and two summer sampling sessions between 1992 and 1993. For nine other beaches sampled during the summer of 2000, only six macrofaunal species were collected from core samples, with overall population densities ranging from 4.13 to 45.45 individuals m ÿ2 . Only 92 individuals belonging to 12 species were collected by hand-net from the uppermost infralittoral of five beaches sampled using this method during the summer of 2000. Taxa of gastropods, bivalves, decapods, mysids and staphylinid beetles generally abundant on Mediterranean sandy beaches, were entirely absent from the beaches sampled.Few correlations that could explain the impoverishment of Maltese sandy beaches were found between physical parameters and faunal abundances, and other factors such as inadequate sampling effort, human disturbance and marine pollution were also excluded; however, seasonally biased sampling may partly explain the results obtained. One factor that may explain why certain species are missing could be lack of recruitment, due to Malta's geographical isolation from the European and African mainlands.

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Section: Methodsmentioning

confidence: 99%

Low faunal diversity on Maltese sandy beaches: fact or artefact?

Deidun

Azzopardi

Saliba

et al. 2003

Estuarine, Coastal and Shelf Science

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“…Wave fetch, which can be used as a wave exposure index-a measurement related to magnitude and frequency of surge-has proved to be an important predictor of intertidal communities (Thomas 1986;Burrows et al 2008). In the northeast Pacific, several recent studies on the distribution and abundance of intertidal organisms have spanned the same coastline and included many of the same sites (Connolly and Roughgarden 1998;Schoch et al 2006;Blanchette et al 2008).…”

Section: Discussionmentioning

confidence: 99%

“…Superimposed on this more or less predictable variation in exposure is a much more unpredictable regime of exposure to wet and dry conditions created by the splash and surge of wave action (Thomas 1986). Splash occurs as water droplets caused by waves spray over the intertidal surface, moistening it while it is still aerially exposed.…”

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confidence: 99%

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Spatial variability of emergence, splash, surge, and submergence in wave‐exposed rocky‐shore ecosystems

Mislan

Blanchette

Broitman

et al. 2011

Limnology & Oceanography

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To distinguish the intertidal states of emergence, splash, surge, and submergence and record their relative durations, we deployed a water-level logger paired with a temperature logger in the mid-intertidal zone at each of 10 wave-exposed sites during the summer in the northeast Pacific. Relative durations of intertidal states were different among the different sites, even at sites close together. Splash was temporally variable, being recorded by the loggers on 50% or fewer days at most sites. Daily surge durations tended to be longer at sites in northern and central California compared with sites in Oregon and Washington. Return times to surge and submergence showed the opposite trend with longer return times in Oregon and Washington compared with California. We estimated the effect of interannual changes in tides on intertidal states by applying the logger data to tidal predictions and comparing duration and return time over the 18.6-yr tidal epoch. Over long time periods, compared with the logger deployments, daily durations of surge increased, return times to the surge state became more uniform, and return times to submergence lengthened.

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“…Exposure to wave action was determined using the method described by Thomas (1986). The parameter 'beach length' was log transformed to reduce the large differences in values obtained for the different beaches (range 0.08-0.50 km).…”

Section: Monitoring Of Environmental Parametersmentioning

confidence: 99%

Long or short? Investigating the effect of beach length and other environmental parameters on macrofaunal assemblages of Maltese pocket beaches

Deidun

Schembri

2008

Estuarine, Coastal and Shelf Science

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Keywords: macrofaunal assemblages sandy beaches psammophiles beach length beach width a b s t r a c t Despite numerous published studies that have evaluated the influence of different physical parameters, including beach slope, sediment organic content and grain size, on beach macrofaunal assemblages, very few studies have investigated the influence of beach length on biotic attributes of the same assemblages. Four beaches on the Maltese Islands were sampled using pitfall traps at night for eight consecutive seasons during [2001][2002][2003]. Macrofaunal collections were dominated by arthropods, mostly isopods (especially Tylos europaeus) and tenebrionid beetles (especially Phaleria spp.). The environmental variables of beach slope, exposure to wave action, sediment organic content, mean particle diameter, log beach length, beach width and the beach deposit index (BDI) were regressed against a number of biotic parameters, including log individual abundance, total species, Shannon-Wiener (H 0 ) diversity index value and the psammophilic fraction of the total species collected, whilst BIO-ENV and NMDS were used to identify the physical parameter which could best explain observed biotic patterns. RELATE was used to assess the long-term persistence of macrofaunal assemblages on beaches of different lengths. Results from this study suggest that, whilst the influence of beach length and beach width on individual abundance and total species number is unimportant, these 'beach-area' parameters may affect the taxonomic composition of a beach assemblage, mainly in terms of the psammophilic fraction of assemblages, as well as the permanence of macrofaunal assemblages on a beach. Shorter and narrower beaches were found to be more prone to sporadic and random events of colonisation by euryoecious species. In the absence of human disturbance and mass mortality events, beaches of limited dimensions can still maintain stable macrofaunal assemblages. Individual abundance and total species number could not be related to a single or small suite of physical parameters. The study further highlights the need to include biological interactions, the degree of human disturbance and other variables such as environmental heterogeneity and the connectivity of the individual beaches when assessing inter-beach differences in macrofaunal assemblages.

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A physically derived exposure index for marine shorelines

Cited by 65 publications

References 30 publications

Low faunal diversity on Maltese sandy beaches: fact or artefact?

Low faunal diversity on Maltese sandy beaches: fact or artefact?

Spatial variability of emergence, splash, surge, and submergence in wave‐exposed rocky‐shore ecosystems

Long or short? Investigating the effect of beach length and other environmental parameters on macrofaunal assemblages of Maltese pocket beaches

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