Tracking Summer Flounder in an Estuary Creek: A WebQuest for 5-8th Grade (Biology)

National Science Standards Addressed (Grades 5-8)

Variations:

If the students need to pair up on the computers they will answer the questions together and come up with similar conclusions. If time is a factor, you may want to do it this way and have class discussions about the questions and data (especially if the students are not familiar with looking at graphs).

Human Resources:

One teacher is needed to implement this, but aides or parents are a plus!

Tracking Summer Flounder in an Estuary Creek Vocabulary and Task Questions

Some words and concepts the students should be familiar with before they begin:

1. Age-0: less than one year old
2. Continental Shelf: An extension of the same crustal rock that makes up the continent, but submerged underwater. It is relatively flat and can be covered with thick mud and sand layers. Off New Jersey it extends almost 75 miles from the shore to the shelf edge.
3. Dorsal: pertaining to the back or upper surface of an animal’s body.
4. Estuary: Region where fresh water flows into the ocean. On the east coast of the US, this is often inside shallow valleys that have been flooded by rising sea level, so that estuaries take on the shape of bays with marshy edges.
5. Habitat: where an animal lives; its natural home. This may change during the life stages of the animal.
6. Juvenile: immature, not fully developed
7. Ecosystem: All the living organisms in a given area and non-living factors with which they interact.
8. Migration: Two-way journey completed by fish to take advantage of the fact that different needs for different life stages are best provided for in different habitats.
9. Tide: The periodic rise and fall of the sea level resulting from the gravity of the moon and sun on the earth. In New Jersey there are two high tides and two low tides daily.
10. Hydrophone: An underwater microphone.
11. Ultrasonic: Sound waves with such high frequency (number of waves passing a point in a second), that they cannot be heard by the human ear.
12. Leaving Patterns: how migrating animals leave one place and go to another
13. Transect: to cut sections
14. Dissolved Oxygen (DO): Molecular oxygen (O2) present in water, not the O in H2O. Oxygen gets into water from the surrounding air, by aeration (rapid movement), and as a waste product from photosynthesis.
15. Salinity: The total dissolved salt content in water. In sea water, most of this salt is NaCl, familiar as table salt, but there are many other kinds included. Coastal ocean water in this region is typically 3.4% (or 34 parts salt per thousand parts water)
16. One meter = how many inches? One meter = 39.4 inches

Task one: The JCNERR

Q: Why are estuaries so important? Hint: Look at the plants, animals, history of the area, geography, geology. You may want to visit another estuary site for general information. It never hurts to get additional information, and you may impress the teacher.

A: 1) land buffer against storms, 2) major stop for migrating birds (70,000 individuals in the winter), 3) habitat for young fish and nesting grounds for birds.

Q: What is unique about this estuary? Hint: Take a look at the Mullica-Great Bay Watershed and the whole reserve.

A: The Reserve offers a wide range of different habitats, including: upland pine-oak forests, lowland Atlantic white cedar swamps, freshwater marshes, salt and freshwater tidal marshes, barrier islands (including sandy beaches and dune habitats), shallow bays, and the coastal ocean.”

Since the estuary is part of a reserve, the area up stream is pretty much undeveloped. Thus, the whole river system is relatively pristine. Estuaries in other states are not so fortunate.

Q: Visit this site a little longer to read about and see all of the components in the reserve. How does one affect another?

A: The Mullica River and its tributaries travel through the forests and swamps before emptying into the bay. Anything that happens to the water in the upper reaches of the system will affect the lower reaches.

Task Two: Research of Paralichthys dentatus

Q: What parts of the estuary do summer flounder frequent and why?

A: Adults usually prefer hard sandy substrate where they can burrow; can exploit a broad range of lower and mid-estuary habitats including salt marsh creeks and seagrass beds, which usually have muddy or silty substrates, as well as sand flats. Occurs in bays, lagoons and shallow coastal waters.

Q: What ways are flounder prepared and consumed by humans? Have you ever eaten flounder?

A: Utilized fresh and frozen; can be steamed, fried, boiled, microwaved and baked and of course Sushi!

Q: What are two adaptations this order of fish has made to the environment?

A: Their bodies are highly compressed. Eye Migration (the right eye moves around to the left side of the head during the larval stage causing the fish to be flat.) Their eyes can protrude above body surface allowing fish to see when buried in the substrate. Adults almost always do not have a swim bladder, allowing them to stay on the bottom.

Q: What are some challenges in this environment?

A: Students need to think about this one. Living on the bottom can be dangerous because of fishermen’s nets. Also, bottom dwellers are exposed to the sediments that may contain toxins washed into the ocean from the rain or from the land. Sometimes, their food supply may be limited.

Task Three: The method, the data and the map

Q: Why did they only tag nine fish?

A: Tagging studies are very time consuming. A small study sample is necessary to keep track of all the tagged fish without needing an army out there looking for them.

Q: Was the creek a large enough study area?

A: Yes, once again, a small area can be handled by one or two technicians or scientists.

Q: What are some challenges in choosing this tagging and tracking method?

A: The ultrasonic tags are very expensive. Setting up the study area and the hydrophones in a way that catches all the movements of the fish. Fishermen may catch and keep a tagged fish. Time and patience are essential.

Q: When did they track using the portable method? Why?

A: They tracked the fish in kayaks. Initial detection was recorded on a detailed map of the creek. Then the creek was searched every six hours during slack water. Slack water is the time just before a high or low tide when the current is minimal.

Q: Where was the stationary hydrophone and what direction was it pointing?

A: The stationary hydrophone was placed approximately 150 meters from the creek mouth on a point of land near the boat basin. (see map) It was pointing out toward the map and was good for detecting about 130 meters in front of it.

Q: What is "missing time?"

A: A "missing" category accounted for the time it was known the fish was in the creek but could not specifically locate it. For example, if a particular fish was located at the mouth at 6:00 am and in the upper creek at 12:00 pm, but did not detect it moving up the creek, 6 hours were placed in the "missing" category.

Q: What is a refractometer?

A: An instrument used to measure salinity by measuring the indices of refraction in the water.

Build a map.

The students have a map with only the creek mouth marked. Have them use the legend to fill in every 100 meters up to 600m, the stationary hydrophone, the tide station and the release site. All of this can be found in the lesson.

Task Four: Analyze the data and draw conclusions

Q: What information does the data provide?

A: 1) The total time each fish spent in each of the three locations and time missing. 2) Movement of the fish between high and low tides 3) Mean water temperature, salinity and dissolved oxygen.

Q: Where did the fish spend most of their time and why?

A: Look at the graph "Total time in each location." The student can see that the mouth was the most preferred location. Why? The mouth area served as a low-energy holding area because its physical configuration probably produced a low current area during both flood and ebb tides.

Q: What do you think happened to fish A, C, F and H?

A: Looking at "Total time in each location" and "Movement" graphs, the students can see that the data for A, C, F, H is very limited. This is because these fish left the creek quickly after being released. This rapid exit may have been caused by the stress associated with capture, handling, and transmitter attachment.

Q: What does "mean" DO, Temperature and Salinity tell us?

A: Mean means average. Have the students look at these with and without fish A, C, F, and H. Compare each fish with the average.

Q: What property/properties of water would cause the fish to move?

A: Water temperatures and dissolved oxygen concentrations in the creek on several instances were well outside the average values and may have affected fish movements. These factors along with high and low tides caused the fish to move (energy conservation). The fish move up the creek during high tide and down the creek during low tide. (Movement graph) By late September, cool autumn temperatures in the creek ultimately caused the flounder to move out to the shelf where the water is temperature is warmer and more consistent.

Task Five: List reasons to protect

Q: What steps can we take as responsible stewards on planet Earth to be sure that this habitat is healthy and available to future generations of fishes?

A: Scientific data is important to present to decision makers in our community, state or nation. With more and more people on the planet, natural areas like estuaries may be considered for shopping malls and parking lots. Or take a look at Atlantic City. Encourage your students to dig deep, get passionate and understand that they are responsible for the future of our planet and it begins in their own communities.