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Most rocky intertidal zone field studies require quantification of abundance, of either individual species or other taxonomic units of the investigator's choice. Data indicating species abundances can be collected quickly using subjective scales or by determining the presence of species in defined sampling units. This chapter reviews various methods of quantifying the density and cover of rocky intertidal populations using nondestructive sampling procedures. It discusses procedures used to collect abundance data during rapid surveys and while using plotless and line transect sampling methods. It focuses on plot- or quadrat-based methods for determining density and cover of intertidal macroalgae and macroinvertebrates. Differences between plots and quadrats are somewhat semantic and the terms are used as functional synonyms in this chapter.

The biological units targeted by a sampling program can vary from individual-based parameters such as the size of a particular limpet species' gonads, to population-level parameters such as counts of all macroscopic organisms, to higher taxonomic units such as the numbers of phyla. The biological units to be selected will vary (as always) with the goals of the sampling program and with available knowledge about the ecology of the populations and communities being studied. The investigator will want to choose the most informative biological units—that is, those that best address the goals of the study and that have the potential to provide statistically powerful answers to the specific research questions. Ideally, the chosen biological units also will have known causal links with any stressors being studied. Unfortunately, clear causal relationships between stressors and responses of organisms in rocky shores are rarely known, even when only a single identifiable stressor is under consideration. Of the biological units targeted in intertidal zone monitoring, impact detection, and other research programs, the species-level population is the most commonly sampled unit.

A wide variety of sampling units can be used for intertidal zone field studies. The most common units include line transects and plots or quadrats. In addition, plotless designs are sometimes used. The choice of sampling unit depends on the goals of the sampling program, especially the species to be sampled. This chapter explains how to choose the type of sampling units in order to get accurate estimates of species abundances at a study site. Sampling can be conducted using either quadrat or plot methods or plotless methods. Plots, which are the most commonly used sampling units, are discussed first. Plotless designs, which utilize some scheme to determine which elements in the environment are sampled, are discussed next. Plotless methods have rarely been used in intertidal habitats, but they might actually be the best choice for some problematic species, such as those with large individuals occurring at low densities. Finally, sampling strategies for two intertidal habitats that provide special challenges, tidepools and boulder fields, are considered.

For any intertidal zone sampling program, site selection probably has the greatest influence on the overall program design. Unless sampling is intentionally confined to one location, and site comparisons are not needed, site selection is an important decision—one on which all conclusions obtained from the sampling program will be based. If sites to be compared are not physically similar, then physical differences can confound any conclusions about what might cause or correlate with any detected differences or trends. This chapter discusses procedures for site selection, including the classification of shorelines to avoid confounding problems resulting from differences in geophysical site characteristics. It also reviews the utility of shoreline habitat maps and the pros and cons of sampling particular microhabitats on rocky shores. In addition, it considers how sites should be selected based on program goals and how these goals will differ depending on the objectives of the sampling program. Finally, the chapter examines the key role of replicating sites in developing a robust study design.

Field sampling programs provide the information needed to determine the status and dynamics of populations and communities and thus are the foundation for many kinds of research, including impact studies as well as monitoring studies. Certain habitat types present more formidable challenges compared with others when it comes to designing and performing field studies. The rocky intertidal zone is one of these habitat types. Unlike terrestrial habitats, the intertidal zone is accessible for most studies only during limited periods when the tide is low. The steps in designing a field sampling program include identifying the study goals, including the questions to be answered by the study or the hypotheses to be tested, and developing an effective and statistically powerful study design.

Salt marshes dominate the intertidal zone in temperate latitudes and present some unique features pertaining to measurement of primary production. Several destructive harvest and non-destructive methods for quantifying salt marsh production are described. Allometric methods that account for stem turnover are the recommended approach. Field and laboratory procedures illustrating the recommended protocol are detailed using examples from LTER sites.

Most rocky intertidal zone monitoring and impact studies are designed to determine the status of sampled populations solely in terms of abundance. This approach can present two problems. First, abundance data alone do not adequately describe a population in a way that depicts its dynamics. Population density is a result of primary and secondary population parameters. A second problem involves the high “noise-to-signal” ratio because of the usual high variation obtained when sampling for abundance data or other population-based parameters. This chapter describes selected approaches for measuring secondary population parameters in rocky intertidal organisms. It focuses on procedures used to determine age and class size distributions, growth rates, sex or phase ratios, and reproduction in seaweeds and benthic invertebrates.

Population dynamics of plant species of coastal sand dunes is influenced directly, both above and below the soil surface, by a wide variety of organisms. Plants serve as sources of carbon and pathogens including viruses, insects, bacteria, fungi, birds, and mammals of various kinds. Some enhance plant performance while others have deleterious effects. Positive interactions include pollination of flowers by useful insects in return for nectar and pollen, nutrient acquisition from soil by mycorrhizal fungi in exchange for carbon and acquiring nitrogen (N) from N-fixing bacteria. In the history of co-evolution between plants and organisms over one hundred million years plants have developed many mechanisms to defend themselves from pathogens. Morphology may be altered by producing epicuticular waxes, developing trichomes over leaves, producing tough leaves with deposition of celluloses, lignin, suberin and callose, developing thorns on stems and branches or producing secondary plant metabolites that retard development, intoxicate or kill herbivorous insects. Herbivory may induce a plant to produce chemicals that signal to advertise the presence of insects feeding on them and attract parasites to reduce their numbers. Phenological escape is also employed, such as delay of leaf expansion during periods of insect abundance. Some indirect mechanisms of plant defence involve the use of insects such as ants for protection from other phytophagous insects. However, the predators have also evolved the ability to break down the defence mechanisms of the plant. For example, they may use phytochemicals for their own defence or as olfactory clues for feeding. In this chapter a brief account of organisms of the coastal dune communities, including species of the intertidal zone, scavengers of the sea coast, reptiles, birds, insects, mammals and their possible interactions with terrestrial vegetation is presented. For biological organisms of the seashore the intertidal zone is the most important for food and shelter. The sand-dwelling species of the seashore must be able to contend with four limiting factors: (i) rush of water from the approaching or receding high tide and pounding breakers, (ii) low salinity of the top surface of sand (iii) desiccation of surface by high winds and sunshine and (iv) extreme changes in temperature of topsoil.

Plant communities of the dune complex are a result of interaction between tolerance of plant species and sandy substrate, high wind velocities, salt spray, sand accretion and environmental heterogeneity. Propagules of many plant species are dispersed by water currents and deposited on the driftline. Most of these species find ideal conditions for germination but seedling establishment, growth and reproduction is denied to all but a few species with ecological amplitude sufficient to withstand the physical stresses associated with sand accretion, erosion and sandblasting in the highly disturbed environment. The distinct differences between habitats from the water´s edge to the inland grass-forest ecotone leads eventually to the establishment of ecologically distinct communities consisting of both plants and animals. The distinction is caused by sharp differences in the physical environment that may create sharp zones with abrupt or gradual blending of the two community types. In some locations these zones are relatively stable for long periods before any visible change occurs in the community depending on the recession of the shoreline, availability of new bare areas and the advance of communities towards the sea coast. The occurrence of plant communities in zones has been documented along sea coasts worldwide. This chapter examines the plant communities of the sand dune complex along seashores of the world. The following information has been assembled from Doing (1985), Dry coastal ecosystems Vol. 2 A, B, C, edited by Eddy van der Maarel (1993), Doody (1991) and Thannheiser (1984). It presents data on plant communities and ecology of each zone from various parts of the world. The species complement in the ´foredune complex´ in tropical, temperate and other regions around the world may be different, but their response to the prevailing environmental stresses of foredunes is convergent. In different world regions the boundaries between vegetation zones of the sand dune complex may not be defined sharply because of climatic variability, geographic location, physiography of the dune system and other factors peculiar to each location. Usually three to six different plant assemblages have been identified on the dune complex along sea coasts and lakeshores. A brief description of vegetation and ecological traits of species in each zone are presented below.