Choosing an Intertidal Site

Previous OPIHI sites

If possible, go to a previous OPIHI site. This contributes data to the long-term monitoring scientific goals of OPIHI and allows for an examination of intertidal changes over time.

However, feel free to choose a new OPIHI site if no OPIHI site is near you, if your school is situated near a potentially good site, or if your school regularly utilizes a specific coastal area. OPIHI sites that are within your school’s ahupua‘a are particularly desirable so you and your students can identify with the place that they survey and consider the relationship between local community activities and intertidal organisms.

Criteria for Choosing Sites

Some general criteria when choosing a new OPIHI site:

  • Is the site a rocky bench intertidal area? OPIHI monitors rocky intertidal areas. OPIHI sites can have some sand but should be dominated by a bench (flat rock area) (see Figor boulders. Sandy beaches have less diversity in the intertidal because the shifting substrate does not allow organisms to adhere to the bottom.
  • Is the site safe? Sites with steep drop-offs close to shore or big waves year round need to be avoided. However, a site that is inappropriate in the winter due to high waves may be calm and placid by spring. In general, OPIHI sites should be reasonably flat.
  • Is the site nearby? A site that is near your school may be more engaging to the students, since it is part of their local environment.
  • Is the site accessible? There should not be a long, arduous, steep trek from the bus to the intertidal (and bathrooms nearby are always nice!).
  • How big is the site?
    • The site should be wide enough (along the coast) to accommodate at least five transect groups spaced approximately 2 m apart (10 m wide)—even if you plan to have less transects on your field trip. Even wider sites are preferred.
    • The site should also be at least 10 m long (the distance between the upper intertidal zone, often dominated by snails, and a lower intertidal area that is accessible—no deeper than knee-deep water at low tide). Of course, the shallow water can go on for much further than 10 m [Need Diagram].
  • Is the site diverse? Are there different types of algae? Are there hiding places for organisms? A yes to these questions means the site may be more interesting for people to monitor. While less diverse sites are important to survey as well, just checking off “rock, sand, rock, sand, etc.” on data sheets can get boring.
  • Is the site protected or does it have particularly sensitive, unique, or rare features (environmental and/or cultural)? Some sites are protected by the state (e.g., from algae collection); other sites have unique environmental and cultural features that you might want to expose your students to—or avoid—depending on your goals and focus.
  • Are you interested in the site? If you are interested in and excited about going to a site, that excitement will translate to your students and their interest in the site.

Visit your site

Figure 1. Intertidal benches in Kapa‘a, Kauai and Waipouli Beach, Kauai (Images courtesy of Jessican Schaefer)

It is very important to visit your site prior to your field trip, at a time when the tide level is similar to your field trip. 

  • Some great locations will be covered by water and missed if you only see them at high tide.
  • Take some pictures of the site to share with your students.
  • Look for and identify organisms, especially those that are common, so you know what to expect.
  • Determine where you plan to lay the transects and how long they should be.
  • Look around the area—what safety hazards do you notice that you can be aware of and alert for? Try to anticipate any safety and logistical issues.

Sense of Place

Familiarize yourself with your OPIHI site.

  • Where is your site located? What moku, ahupua‘a, ‘lli, and watershed?
    • Ahupua’a: Ahupua’a have cultural, historical, and spiritual significance. They are tracts of land extending from the highlands to the sea containing the resources of the forest, cultivation sites, the shoreline, and the associated reef.
    • Watershed: A watershed is a western scientific term referring to the area of land where all of the water that falls on it drains to a common outlet (see the Atlas of Hawaiian Watersheds)
  • Research the place name(s)—what do they mean?
  • Research the history of the place.
    • What mo‘olelo (stories) are associated with the place?
    • What historical events have occured at the site or nearby?
  • What current human and environmental threats do the watershed and associated intertidal system face?
    • What anthropogenic (human) influences are there (e.g., Is the site near a developed/developing area? Is the site near sources of fertilizer?)?

You can also have your students research this information, and/or share this information in class while preparing for the trip or on site during the field trip.