**Session No. 2**

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

**Course Title: Coastal Hazards Management**

**Session Title: Rocky Shores**

**Author: Professor John J. Bruno, University of North Carolina at
Chapel Hill**

**Time: 1 hour**

**\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_**

**Objectives**

> 2.1 Define some basic terms of ecology (e.g., habitat, community,
>
> ecosystem, competition, predation, and facilitation).

2.2 Summarize the physical setting of rocky shore habitats.

2.3 Give examples of some common organisms inhabiting rocky shores.

> 2.4 Summarize the typical zonation of an intertidal rocky shore

community.

> 2.5 Discuss the role of biological interactions, physical
>
> disturbance, and physiological stress in structuring rocky shore
>
> communities.

2.6 Discuss some of the hazards to rocky shore communities

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

**Scope:**

Session Two serves to introduce students to basic ecological concepts
and terms and the ecology of rocky shore communities. It also covers
some of the anthropogenic threats facing this community. Most students
without a background in biology will not be familiar with basic
ecological terms (e.g., *competition;* *facilitation*) and the common
organisms inhabiting rocky shores. The lecture, therefore, is very
basic, focusing on conveying general principles and key features of the
rocky shore community. The material describes the fundamental biology
and taxonomy of even very common rocky shore species (e.g., barnacles
and mussels).

This session is the first of four that will set the stage for the
remainder of the course. The information presented in Sessions Two,
Three, Four and Five will contribute to the students' general
understanding of the coast, coastal processes, and the natural systems
that shape the coastal zone. This background information is essential to
a broader understanding of the role of human beings in managing the
coastal zone, and in particular, the natural hazards that are unique to
the coastal zone, as discussed throughout the remainder of the course.

As foundation classes, Sessions Two through Five will present basic
information in a predominantly lecture format, supported by PowerPoint
slides. The slides are an essential part of this lecture series, as they
depict many of the habitats and organisms found in various coastal
environments.

**Readings:**

*Instructor and Student Reading*:

Bertness, M.D. 1999. *The Ecology of Atlantic Shorelines*. Sunderland,
MA: Sinauer, pp. 1-36, Chapter 1: "The Setting."

Bertness, M.D. 1999. *The Ecology of Atlantic Shorelines*. Sunderland,
MA: Sinauer, pp. 177-248, Chapter 5: "Rocky Shores."

*Additional Background Reading*:

Peterson, C.H. et al. 2003. "Long-term ecosystem responses to the Exxon
Valdez oil spill." *Science* 302: 2082-2086.

Menge, B. A. and G.M. Branch. 2001. "Rocky intertidal communities" in
M.D. Bertness, M.E. Hay, and S.D. Gaines (eds.) *Marine Community
Ecology*. Sunderland, MA: Sinauer, pp. 221-251.

Castilla, J.C. 1999. "Coastal marine communities: Trends and
perspectives from human-exclusion experiments." *Trends in Ecology and
Evolution* 14:280-283.

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

**General Requirements:**

The content of this session is to be presented as a lecture supported by
PowerPoint slides.

The course preparers have organized the subject matter in Sessions Two
through Five to be presented as lecture with accompanying slides.
However, the instructor may choose to canvass the class to discover if
any students have a background in zoology, biology or ecology, in which
case further in-depth discussion of the material may be encouraged.

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

#### 

#### **PowerPoint Slides**

> **PowerPoint** **2.1** Basic Ecological Concepts and Terms
>
> **PowerPoint** **2.3** The Physical Setting of Rocky Shores
>
> **PowerPoint** **2.3** Inhabitants of Rocky Shore Habitats
>
> **PowerPoint** **2.4** Rocky Shore Zonation

**PowerPoint** **2.5** Rocky Shore Zonation

> **PowerPoint** **2.6** Rocky Shore Zonation
>
> **PowerPoint** **2.7** Rocky Shore Zonation
>
> **PowerPoint 2.8** Effects of oil spills on rocky shore communities

**Supplemental Considerations:**

Rocky intertidal habitats have served as a model ecosystem for
descriptive and experimental ecology for over 50 years. Much of our
basic understanding of how ecosystems in general work comes from this
habitat. It is a relatively simple system, the plants and animals are
small (and can thus be easily moved, etc.) and environmental gradients
occur over short distances, which

facilitates ecological studies. There are extensive collections of
natural history information and images on rocky shore communities
available on the internet (e.g.,
<http://life.bio.sunysb.edu/marinebio/rockyshore.html>)

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

**Objective 2.1** Define some basic terms of ecology (e.g., habitat,
community,

> ecosystem, competition, predation, and facilitation).

**Requirements:**

The content should be presented as lecture, supported by PowerPoint
slide.

The following PowerPoint slide will be used during this Objective:

> **PowerPoint** **2.1** Basic Ecological Concepts and Terms

**Remarks:**

####### Basic ecological concepts and terms

> **\[PowerPoint** **2.1** Basic Ecological Concepts and Terms\]

-   A **habitat** is a structure or setting that can be occupied by
    plants and animals

    -   *For example:*

        -   rocky intertidal

        -   mountain top habitats

    ```{=html}
    <!-- -->
    ```
    -   Most **marine habitats** are generated by the presence of
        organisms such as grasses, large algae, and bivalves

        -   *For example:*

            -   sea grass beds

            -   kelp forests

            -   oyster reefs

            -   mussel beds

            -   coral reefs

    -   Species that generate whole habitats are called **ecosystem
        engineers** or **foundation species**.

        -   They often increase species diversity and **facilitate** the
            presence of numerous associated species by reducing
            environmental stress, such as

            -   salinity

            -   thermal stress, or

            -   predation intensity

        -   The complex structures they form reduce the ability of
            predators to catch their prey and thus create a
            **predation** **refuge**.

```{=html}
<!-- -->
```
-   A **community** consists of all the species that occupy a habitat
    and interact with each other and the environment.

    -   Interactions between species can be:

        -   **uni**- or **bidirectional** (i.e., the interaction can
            affect one or both of them),

        -   **neutral, positive**, or **negative**, (in terms of the net
            effect on growth and reproductive rates, survival, density,
            etc.) or

        -   s**trong** or **weak** (some interactions have little effect
            even on the species involved while other profoundly affect
            the whole community).

    ```{=html}
    <!-- -->
    ```
    -   An **ecosystem** is a community of organisms and their physical
        environment (habitat) and includes the fluxes of energy,
        chemicals, and materials that flow among them.

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

**Objective 2.2** Summarize the physical setting of rocky shore
habitats.

**Requirements:**

The content should be presented as lecture, supported by PowerPoint
slide.

The following slide will be used during this Objective:

> **PowerPoint** **2.2** The Physical Setting of Rocky Shores

**Remarks:**

####### Physical Setting

> **\[PowerPoint** **2.2** The Physical Setting of Rocky Shores\]

-   **Global distribution and geology of rocky shore habitats**

    -   Rocky shoreline habitats are found throughout the world, but are
        especially **abundant in temperate locations** where glacial
        scouring has removed sediments from coastlines.

-   **Tides**

    -   **Rocky intertidal habitats** are a **transition zone** where
        two major environments (the land and the sea) meet.

    -   Each day, sometimes several times a day, portions of the
        shoreline are **submerged or exposed**. These tidal fluctuations
        can be small or as much as 15 meters per day.

    -   When the **tide is in**, marine organisms **feed and
        reproduce**.

    -   Conversely, **low tide** can be a **highly stressful** period
        for most marine plants and animals.

    -   Tides are generated by the **gravitational pull of the sun and
        moon** acting on the oceans.

```{=html}
<!-- -->
```
-   **Waves**

    -   Locally generated waves and open swells frequently break on
        rocky intertidal habitats on exposed shorelines.

    -   Waves can be important forces structuring the abundance,
        zonation, and diversity of intertidal species (see discussion
        below).

    -   Intertidal **organisms experience enormous forces** when large
        waves break on the shore and have evolved adaptations to cope
        with this stress:

    -   **Adaptations** include**:**

        -   **Flexibility**: Many intertidal plants are flexible -- they
            simply bend when a wave impacts the shore.

        -   **Group living**: some species live in dense aggregations
            that shelter individuals.

        -   **Flattened and small bodies** increase the attachment area
            relative to overall body mass and reduce sheer forces acting
            on the organism.

    ```{=html}
    <!-- -->
    ```
    -   **Thermal stress**

        -   The longer a portion of the intertidal zone is **exposed to
            the air and sun** during low tide, the greater the
            **cumulative thermal stress**.

        -   **Exposure to the air** desiccates marine plants and
            animals. Some can only survive seconds of aerial exposure,
            while others can tolerate being exposed for hours or even
            days.

        -   **Direct exposure to the sun** can also increase the body
            temperatures of intertidal animals by 10° C or more, which
            can be **lethal**.

        -   Additionally, the **rock surface can heat up** during low
            tide, which compounds this thermal stress.

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

**Objective 2.3** Give examples of some common organisms inhabiting
rocky shores.

**Requirements:**

The content should be presented as lecture, supported by PowerPoint
slide.

The following PowerPoint slide will be used during this Objective:

> **PowerPoint** **2.3** Inhabitants of Rocky Shore Habitats

**Remarks:**

-   Only a **few, highly adapted marine species** can survive the degree
    of exposure experienced in the high intertidal zone. In general,
    there is a **gradient of physiological stress** that increases with
    the height of the intertdial zone and degree of aerial exposure.

    -   Being **lower on the shore is better**, since this means being
        submerged for longer.

    -   However, living in the lower intertidal can include **additional
        hazards** such as an increased chance of encountering a predator
        or other enemy.

####### Community Description

-   **Inhabitants of intertidal rocky shore communities**

> **\[PowerPoint** **2.3** Inhabitants of Rocky Shore Habitats\]

-   Rocky intertidal habitats are dominated by **small invertebrates**
    and **macro algae**.

-   The **base of the intertidal food web** is made up of the primary
    producers which mainly consist of the algae that live on the rocks
    and in the tide pools and phytoplankton in the water.

    -   **Phytoplankton** are consumed by herbivorous zooplankton, that
        are in turn consumed by filter-feeding organisms such as
        barnacles and mussels.

        -   **Filter-feeders** remove food from the water column when
            they are submerged (during high tide).

    -   **Macroalgae** are consumed by benthic animals (species that
        live on the bottom as opposed to pelagic species that live in
        the water) including

        -   snails

        -   chitons

        -   urchins, and

        -   limpets.

    -   These grazers and numerous filter-feeders are **consumed by a
        suite of** **predators** including starfish, carnivorous snails,
        fish, and birds.

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

**Objective 2.4** Summarize the typical zonation of an intertidal rocky
shore

community.

**Requirements:**

The content should be presented as lecture, supported by PowerPoint
slides.

The following slides will be used during this Objective:

> **PowerPoint** **2.4** Rocky Shore Zonation

**PowerPoint** **2.5** Rocky Shore Zonation

> **PowerPoint** **2.6** Rocky Shore Zonation
>
> **PowerPoint** **2.7** Rocky Shore Zonation

**Remarks:**

####### Zonation of rocky shore communities

> **\[PowerPoint** **2.4** Rocky Shore Zonation\]

-   **High Intertidal Zone**

    -   This zone is **rarely submerged** and is only occupied by a
        **few tolerant species** including herbivorous snails and
        occasional barnacles.

> **\[PowerPoint** **2.5** Rocky Shore Zonation\]
>
> **\[PowerPoint** **2.6** Rocky Shore Zonation\]

-   **Mid Intertidal Zone**

    -   This zone can be very diverse.

    -   The **upper mid intertidal zone** is usually dominated by
        barnacles (that are resistant to desiccation) and sometimes by
        macro algae.

        -   **Barnacles** are especially abundant on exposed shorelines
            with high wave energy. This is probably caused by a
            combination of factors including increased larval and food
            supply and decreased thermal stress via wave splashing.

        ```{=html}
        <!-- -->
        ```
        -   The **lower mid intertidal zone** is usually dominated by
            macroalgae and/or mussels.

            -   **Mussels** usually form extensive beds on exposed
                rocks, in part because the intense waves make it
                difficult for mussel predators (e.g., fish, sea stars,
                and snails) to forage here.

            -   This zone is also occupied by a variety of
                **invertebrates** including **anemones** and **worms**
                that live in calcareous shells.

            -   **Grazers** in the mid intertidal zone include
                **chitons, limpets**, and **snails.**

```{=html}
<!-- -->
```
-   **Low Intertidal zone**

> **\[PowerPoint** **2.7** Rocky Shore Zonation\]

-   The low intertidal zone is dominated by **mussels or algae**,
    depending on wave exposure and other physical factors.

-   **Other invertebrate species** can also be common, especially in
    tide pools.

######## Shallow Subtidal Zone

-   This zone is **always submerged**. It is not physiologically
    stressful and is largely structured by biotic interactions (i.e.,
    competition and predation) and physical disturbance.

-   The makeup of the shallow subtidal zone can also be driven by **wave
    exposure** and **thus herbivore abundance**.

    -   On **very exposed shores**, macroalgae and kelp often dominate
        the shallow subtidal zone down to 1 to 3 m below the surface,
        where light becomes limiting and grazers, especially urchins,
        limit their lower distribution.

    -   On **exposed shores**, waves prevent larger herbivores from
        moving into the shallowest subtidal zone.

    -   On **protected shores**, macroalgae can be less common, and the
        rock surface is usually dominated by filter-feed animals (e.g.,
        tunicates, bryozoans, and corals).

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

**Objective 2.5** Discuss the role of biological interactions, physical
disturbance, and physiological stress in structuring rocky shore
communities.

**Requirements:**

The content should be presented as lecture.

**Remarks:**

*Ecological Processes*

> There are a wide variety of different types of species interactions.
> However, in general when two individuals interact, they either have
> neutral, positive, or negative effects on each other and most
> interactions can be categorized broadly as **competition, predation,
> or** **facilitation.**
>
> **Competition** occurs when two individuals compete for a limiting but
> necessary resource (e.g., light, space, food, nutrient, nesting sites,
> etc.) and the interaction has a negative effect on the **reproductive
> fitness** of one of them. This means that the individual being harmed
> has a **lower survivorship**, growth rate or reproductive output.
> Competition can occur within **(intra-specific competition)** or
> between species **(inter-specific** **competition)**. Species that are
> good competitors are often able to **monopolize resources** and in
> some cases actively harm the neighbors they are competing with by
> growing over them or releasing **noxious chemicals.**
>
> Competitive interactions can be so severe that an individual or entire
> species is excluded from an area. This process, termed competitive
> exclusion, can be responsible for many of the patterns of species
> distributions and biodiversity that we observe in rocky shore and
> other habitats. In many rocky shore habitats, mussels are the
> competitive dominant species, and they actively exclude other large
> invertebrates and plants from the low intertidal zone. Barnacles also
> compete for space and competitively inferior species and individuals
> are usually only able to survive in the high intertidal zone, the most
> physiologically stressful location.
>
> Several ecological processes usually prevent a competitive dominant
> from completely excluding all other species. These processes thus
> enable other species to live in a habitat and help maintain species
> diversity. One such process is physical disturbance (e.g., breaking
> waves and logs impacting the shoreline), which can remove competitive
> dominants and open space for inferior competitors. Another is
> predation, where predators consume competitive dominants. Predation is
> a broad category of interaction that includes herbivory (the
> consumption of plants and other photosynthetic organisms), carnivory,
> canablism, and parasitism.
>
> Not all species interactions are negative. In fact in some habitats,
> most neighbors have positive effects on each other. Positive species
> interactions are broadly classified as **facilitations,** which can be
> defined as an interaction that benefits one individual and harms
> neither. Facilitators often modify the environment and ameliorate
> stressful conditions. Like competition and predation, facilitation can
> influence species distributions by enabling individuals to live in a
> habitat or location that would otherwise be too harsh. For example,
> large macroalgae shade the shoreline during low tide reducing thermal
> and dessication stress for species that live underneath the algal
> canopy. Even competitive dominants can be facilitators. Mussels, for
> instance, facilitate hundreds of small invertebrates that live within
> the mussel bed, where environment stress is much lower.
>
> Facilitation is usually more important in environments that are
> stressful (e.g., too hot, sunny, or salty) or where predators are
> especially abundant. For example, facilitation is very common in the
> high rocky intertidal zone, where thermal stress is the greatest.

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

**Objective 2.6 Discuss some of the hazards to rocky shore communities**

**Requirements:**

The content should be presented as lecture, supported by PowerPoint
slide.

The following slide will be used during this Objective:

##### PowerPoint 2.8 Effects of oil spills on rocky shore communities

**Remarks:**

####### 

####### Hazards and Anthropogenic threats 

-   **[Oil spills]{.underline}**

    -   Oil spills are a **major threat** to rocky shore and other
        coastal **marine communities**.

        -   Two well known *recent examples* are the 1989 Exxon Valdez
            spill in Alaska
            (<http://response.restoration.noaa.gov/spotlight/spotlight.html>,
            <http://www.evostc.state.ak.us/>) and the more recent 2002
            Prestige spill in Spain.

##### \[PowerPoint 2.8 Effects of oil spills on rocky shore communities\]

-   **The Exxon Valdez** **oil spill** released 42 million liters of
    crude oil into Prince William Sound Alaska, contaminating 2000 km of
    pristine shoreline. **Short-term effects** included:

    -   combination of oiling and washing treatments (i.e., hot water,
        chemicals, and high-pressure application to remove the oil from
        rocks);

    -   dramatically reduced the cover;

    -   reduced abundance of intertidal plants and animals;

    -   A \$2.8 billion loss in recreation/tourism income.

    -   The spill also affected fish, bird, and marine mammal
        populations that used rocky intertidal habitats.

```{=html}
<!-- -->
```
-   **15 years later -- lingering impacts:**

> It was originally assumed that the main impacts of the spill would
> result from oil-induced acute mortality and that the oil would
> dissipate. Fifteen years of research on the affect of the spill
> indicate that **in many respects the system has recovered, but by some
> measures it has not.**

-   Signs of the spill are currently not obvious to the casual observer.
    Oil is generally not evident on the surface, but is still present
    below the surface on cobble/gravel beaches and in subtidal soft
    sediment habitats.

```{=html}
<!-- -->
```
-   The system has generally returned to the state it was in before the
    spill. However, monitoring has revealed extensive yearly to decadal
    variability in population abundances likely driven by natural
    factors not related to the spill.

-   Most intertidal species "recovered" (returned to a state similar to
    unoiled sites) by 1992.

```{=html}
<!-- -->
```
-   However, some species have not entirely recovered. This is thought
    to be due to chronic effects of remaining oil that reduce health,
    growth, reproduction, and survival.

-   Additionally, these lingering chronic affects continue to indirectly
    affect other species via altered species interactions.

-   One group that still largely exhibits lower population densities at
    oiled sites are infaunal invertebrate animals (e.g., clams and
    worms) that live within the cobble/gravel beaches on portions of the
    rocky shoreline.

-   Some marine birds, mammals, and fish have also not recovered.

```{=html}
<!-- -->
```
-   **[Intertidal fisheries]{.underline}**

    -   In some countries and cultures, **rocky intertidal habitats
        support a large fishery** for a vast array of plant and
        invertebrate species.

    -   In the **United States**, grazing snails, mussels and barnacles
        are all collected for consumption or resale. The **affects are
        generally minimal** for most species.

        -   **Exceptions** include **sites close to large, urban
            populations**.

```{=html}
<!-- -->
```
-   In **Morocco, Spain, and Portugal**, and many other countries
    intertidal fishing **pressure is more intense** and can alter the
    ecosystem at a regional scale.

    -   *For example*, **in Chile**, humans are the dominant consumer in
        the rocky intertidal. They collect and consume a wide variety of
        plants and animals including barnacles, grazing snails and a
        giant limpet.

    -   In small 'no take' reserves that exclude human predators,
        limpets and other large grazers are common and barnacles
        dominate the rocks, however, on most of the coastline limpets
        are rare and macroalgae and mussels dominate.

\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_