Vertical Zonation: Studying Ecological Patterns in the Rocky Intertidal Zone

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  • This article was downloaded by: [Queensland University of Technology]On: 06 November 2014, At: 21:09Publisher: RoutledgeInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,37-41 Mortimer Street, London W1T 3JH, UK

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    Vertical Zonation: Studying Ecological Patterns in theRocky Intertidal ZoneMyndee McNeill aa Oregon Institute of Marine Biology , Charleston, ORPublished online: 07 Aug 2010.

    To cite this article: Myndee McNeill (2010) Vertical Zonation: Studying Ecological Patterns in the Rocky Intertidal Zone,Science Activities: Classroom Projects and Curriculum Ideas, 47:1, 8-14, DOI: 10.1080/00368120903280735

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  • Science Activities, 47:814, 2010Copyright c Taylor & Francis Group, LLCISSN: 0036-8121 print / 1940-1302 onlineDOI: 10.1080/00368120903280735

    Vertical Zonation: Studying EcologicalPatterns in the Rocky Intertidal Zone

    Myndee McNeillOregon Institute of Marine

    Biology,Charleston, OR

    ABSTRACT Vertical zonation is a fascinating and well-studied ecological pat-tern that is readily observable in nature, and general aspects of it can be easilyunderstood by fifth- and sixth-grade students. In this lesson, live animals canbe used to engage student interest, and provide a simple yet effective means ofteaching students about the importance of animal adaptations in determiningan animals distribution in the rocky intertidal zone. Knowledge of differentanimals adaptations, combined with a basic knowledge of the physiologicalstresses faced by these animals that live in what is perhaps the worlds harsh-est biome, enable the students to make predictions about where each of theanimals might be found within the rocky intertidal zone.

    KEYWORDS vertical zonation, adaptations, biome, niche, physiology

    Ecologists find and study patterns in nature. One such pattern that occursfrequently involves the dominance or presence of certain species only in specificareas. This pattern can be attributed to a variety of environmental factors thatprevent a species from establishing itself outside certain boundaries. The patternis apparent in the Rocky Mountains, as when one ascends from the valley floortowards the jagged and seemingly desolate peaks. Lower desert vegetation on thevalley floor gives way, with increasing elevation, to steppe vegetation, which,in turn, is replaced by coniferous trees, until alpine tundra is reached abovethe tree line. This vertical zonation in Rocky Mountain vegetation is generallyattributed to environmental factors including temperature and moisture level.Nowhere is this pattern of vertical zonation more pronounced or seen in sucha small area, however, than in the rocky intertidal zone. The vertical zonationin the rocky intertidal offers students the chance to see a well-researched andobvious pattern and easily investigate some of the factors that cause this patternto occur in nature.

    Vertical zonation in the rocky intertidal zone is evident from the occur-rence of specific organisms within distinct bands. The main zones seen inthe rocky intertidal zone were first characterized in a paper by Stephensonand Stephenson (1949). The upper and lower limits of the organisms occur-rence coincide with horizontal tidal levels, forming four zones: the suprati-dal, high tidal, middle tidal, and low tidal. In this lesson, the supratidalzone is not discussed. In the Pacific Northwest, the high tidal zone isdominated by barnacles. Barnacles give way to mussels in the middle tidalzone; the lower reach of the mussel populations are established by predatory

    Address correspondence to MyndeeMcNeill, Oregon Institute of MarineBiology, P.O. Box 5389, Charleston, OR97420. E-mail: myndee@uoregon.edu

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  • FIGURE 1 Vertical zonation in the Pacific rocky intertidal zone,adapted from Stephenson and Stephenson (1949).

    sea stars (Levinton 1982). The low tidal zone is domi-nated by kelp and surf grass (see Figure 1). In the At-lantic rocky intertidal zone, there is less biodiversity,but the scheme of zonation is similar (see Figure 2).

    In the rocky intertidal zone, as in the mountains,temperature and desiccation are physical factors con-tributing to the presence or dominance of specificorganisms. Other factors affecting the distribution ofspecies within the rocky intertidal zone include waveaction; tidal range; an organisms mobility, competi-tion, and predation; and the physiological tolerance ofan organism to changes in temperature, salinity, andmoisture levels (Levinton 1982). For example, preda-tors such as sea stars need to remain moist in order tohunt and consume prey; hence, sea stars are restrictedto lower tidal levels. This means that the sea stars prey,such as mussels, can find refuge from the sea stars if theylive in higher tidal levels. Therefore, the lower limit, orboundary, of the sea stars prey is determined by theupper limit of the sea star population. This can causea distinct line in the lower part of the rocky intertidalzone below which animals such as mussels are no longerpresent. In general, the upper limit of a species distri-bution is controlled by physical variables and the lower

    FIGURE 2 Vertical zonation in the Atlantic rocky intertidalzone, adapted from Stephenson and Stephenson (1949).

    limit by biological variables. However, for the sake ofsimplicity, this lesson does not address the differencebetween what sets the upper and lower limits specifi-cally. The factors affecting distributions are discussedmore generally, in that they are listed and described asfactors contributing to the overall pattern of verticalzonation. For additional information on this topic, asummary of these factors can be found at the U.K. Ma-rine Special Areas of Conservations Web site (2001; seeReferences).

    This lesson is designed for fifth-grade students, butit could easily be modified for older grades as well. Thefactors leading to vertical zonation could be discussedin greater depth, and additional factors could be dis-cussed as well. Inquiry activities could be designed asan extension to the concepts learned in the first two ses-sions. Ideally, this lesson could be done before, during,or after a trip to the rocky intertidal zone.

    This lesson addresses science content standard C: lifescience in grades 58 from the National Science Educa-tion Standards (National Research Council 1996), whichcovers populations and ecosystems and diversity andadaptations of organisms. This lesson also addressesOcean Literacy: The Essential Principles and Funda-mental Concepts principle 5, concept f: ocean habitatsare defined by environmental factors, and principle 5,concept h: tides, waves and predation cause verti-cal zonation patterns along the shore, influencingthe distribution and diversity of organisms (NationalGeographic Society et al. 2006).

    INTRODUCTIONPrior to this lesson, students should already have

    learned about food chains, so that they are familiarwith the terms predator, prey, and herbivore. Ideally, theyare also aware that different organisms interact witheach other in different ways. This lesson emphasizesthat physical factors, such as temperature and moisturelevels, and interactions between different species, suchas predation, can affect where a species lives. There is alot of room for expanding within this lesson, as manyimportant topics are addressed only briefly. Some ideasfor expanding this lesson are included in Extensionsbelow.

    In this lesson, students identify the pattern of verti-cal zonation in the rocky intertidal zone using picturesdemonstrating the pattern. They learn that differentanimals and plants (algae) live in the different zones.

    Vertical Zonation 9

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  • Waves, tides, predation, and food availability are dis-cussed as four factors that can determine in which zonea species might live.

    This lesson can be conducted in two sessions. Be-tween 30 min and 60 min are required for the first ses-sion. If students are familiar with simple marine foodwebs and ways in which waves and tides affect animalsin the rocky intertidal zone, the first session should re-quire 30 min. More time will be required if more details,such as desiccation or predation in the rocky intertidalzone, need to be explained or discussed. The secondsession requires approximately 60 min. After the firstsession, students should be able to recognize the gen-eral pattern of vertical zonation and the processes thatlead to vertical zonation in the rocky intertidal. Duringthe second session, students apply the information thatthey learned in the first session to make predictionsabout the likely location of various organisms in therocky intertidal zone.

    OBJECTIVESAt the end of this lesson, students will be able to

    explain some factors that lead to vertical zonation inthe rocky intertidal zone, predict how these factors willaffect a species distribution in the rocky intertidal zone,and predict how a species adaptations will affect itsdistribution in the rocky intertidal zone.

    MATERIALSMaterials for Session 1

    Pictures of vertical zonation in the rocky intertidalzone

    Vertical zonation worksheet (see Figure 3)

    Materials for Session 2 Poster or drawing of a rocky intertidal zone (similar

    to Figure 1 or Figure 2)

    FIGURE 3 Student vertical zonation worksheet.

    FIGURE 4 Animal prediction worksheet.

    Pictures of animals from the rocky intertidal zone, orlive animals from the intertidal that are relatively easyto keep alive for a day (if available); depending on lo-cality, these may include mussels, barnacles, whelks,sea stars, snails, littorines or periwinkles, chitons, her-mit crabs, limpets, anemones attached to rocks, andnudibranchs. If two or more students are assigned tostudy the adaptations of the same animal, they candiscuss their predictions together.

    Seawater in tubs, to hold the animals Animal prediction worksheet (see Figure 4), adjusted

    to list the animals (or animal pictures, if pictures arebeing used) brought to class

    One animal card for each student (Figure 5, for ex-ample)

    An information card for each live animal (Figure 6,for example)

    PROCEDURESession 1: Some Factors Causing

    Vertical Zonation1. Show pictures of vertical zonation in the intertidal.

    Point out the different species of organisms in eachpicture, and ask students if they can identify anypatterns in the way that the different species aredistributed in the pictures. Students may use wordssuch as layers or bands to describe the pattern theysee.

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  • FIGURE 5 Sample animal card (for student).

    2. Once students have pointed out the vertical pattern,define the term zone for them. A zone is a horizontalband within the rocky intertidal zone where one seesparticular types of animals or algae but not others.Zones have upper and lower limits.

    3. Ask the students why they think animals and plantsmight live within certain zones. Write a list of theirideas on the board.

    4. Briefly discuss how waves, tides, predators, and foodavailability might affect plants and animals livingin the rocky intertidal zone (see the U.K. MarineSpecial Areas of Conservations Web site; 2001). Re-view how an animals surroundings might changefrom high tide to low tide. Talk about predatorsin the intertidal zone, such as sea stars, gulls, and

    FIGURE 6 Sample information card (to place on table with liveanimal).

    whelks, and what they might eat. Also talk aboutfood sources such as algae and plankton. Point outthat most animals students will be observing are her-bivores that get their food by grazing on plants orare filter feeders that obtain food by eating small ani-mals (zooplankton) and plants (phytoplankton) that livein the water. It might be neither feasible nor prac-tical to discuss all of these factors, so care shouldbe taken in deciding which factors to address, de-pending on students prior knowledge. When thislesson was presented to fifth-grade students, waves,tides (and desiccation), predators, and food availabil-ity were discussed. I showed pictures of huge wavescrashing on the rocks to help the students under-stand the force to which these plants and animalsmay be exposed. When I asked the students whatmay have caused the patterns, their first answer al-ways involved tides or desiccation, so they seemedto understand that concept. Students are always in-terested in the predators of the intertidal zone. How-ever, based on assessment of student understandingfollowing session 2, it seems that food availabilityis a more difficult concept to grasp, so more timeshould be spent on that aspect.

    5. Encourage students to visualize themselves as ma-rine animals experiencing long periods of time inor out of the water, first pounded by waves, thenbaked by the sun. Have the students consider andlist adaptations animals might have to enable themto survive in the various conditions discussed (e.g.,shells to provide protection from predators, hidingunder seaweed to prevent desiccation).

    Vertical Zonation 11

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