STUDENT WORKSHEET FORAYS WITH FORAMS Name______________________________ Date___________________ ACTIVITY: NEW ZEALAND CORE The three laminated sheets represent microscope views of foram samples from layers an ocean core from east of New Zealand: Sample 1 (10,000 ybp), Sample 2 (15,000 ybp), and Sample 3 (20,000 ybp). (YBP = years before present) 1. Using the laminated identification key for Indicator Species and the Data Sheet on Page 2, identify and record the number of each indicator species present in each of the samples. To simplify this exercise in the interest of time, each sample contains 25 forams (with species proportional to the percentages in the actual core). You can check your data by adding the numbers of indicator species recorded for each sample, making sure the total equals 25. 2. For each species identified in a sample, calculate and record that species’ percentage of the total forams in the sample. Because each sample contains 25 forams, 100% of the sample is 25 * 4, so you can use the same proportion to determine each individual species’ percentage. You can check your calculations by adding all percentages in a sample, making sure the total equals 100%. 3. For each sample in the diagram below, plot and color in the percentage of each indicator species in the pie chart, using the colors corresponding to those in the identification key. The blank pie charts are divided into 20 segments, each representing 5%. Starting at the top of the pie (“12 o’clock” position) and proceeding clockwise, plot the species in the order they are listed in the Data Sheet columns. 4. Use the pie chart colors and the Identification Key to determine the Foraminiferal Province for each of the three samples. SAMPLE 1 – 10,000 ybp Foraminiferal Province: ___________________________ SAMPLE 2 – 15,000 ybp Foraminiferal Province: ___________________________ SAMPLE 3 – 20,000 ybp Foraminiferal Province: ___________________________ 5. Based on your results, what happened to ocean temperatures during the period from 20,000 ybp to 10,000 ybp? 6. Can you think of a major climate event that was the likely cause of this trend? Forays with Forams MathScience Innovation Center 2014 PAGE 2 DATA SHEET FORAMINIFERA INDICATOR SPECIES IN CORE SAMPLES SAMPLE 1 10,000 ybp FORAM SPECIES Globorotalia menardii # in Sample % of Sample SAMPLE 2 15,000 ybp # in Sample % of Sample SAMPLE 3 20,000 ybp # in Sample % of Sample Pulleniatina obliquiloculata Neogloboquadrina dutertrei Globigerinella siphonifera Globigerinoides ruber Globigerinoides sacculifer Globorotalia inflata Neogloboquadrina pachyderma (>50% rt. coiling) Globigerina bulloides Globigerina quinqueloba Neogloboquadrina pachyderma (>50% left coiling) Neogloboquadrina pachyderma (≈ all are left coiling Neos) ** TOTALS ** DO NOT enter data in this row unless the sample is composed almost entirely of left coiling Neogloboquadrina pachyderma. Forays with Forams MathScience Innovation Center 2014 ACTIVITY: CHESAPEAKE BAY BENTHIC FORAMINIFERA PAGE 3 The three laminated sheets for this activity represent microscope views of benthic foram samples from a core in the tidal Patuxent River where it joins the Chesapeake Bay. (The field of view represented is the same as for the New Zealand core, approx.. 6 mm diameter.) Samples have been dated for the following calendar years: 1750, 1800, 1850, 1900, 1965, 1975, and 1990 1. Using the laminated identification key for Major Benthic Foraminifera of the Chesapeake Bay and the Data Table on Page 4, identify and record the number of each indicator species present in each of the 3 samples. 2. To simplify this exercise in the interest of time, each sample contains 20 forams (with species proportional to the percentages in the actual core). You can check your data by adding the numbers of indicator species recorded for each sample, making sure the total equals 20. 3. For each species identified in a sample, calculate and record that species’ percentage of the total forams in the sample. Because each sample contains 20 forams, 100% of the sample is 20 * 5, so you can use the same proportion to determine each individual species’ percentage. You can check your calculations by adding all percentages in a sample, making sure the total equals 100%. Using your results in the data table and the descriptions of the benthic foram species in the key, answer the following questions: 4. In what year do you see the first appearance of forams tolerant of low oxygen conditions? 5. In what year do the forams in Question 4 begin to constitute the largest percentage of the benthic species? 6. What is unusual about the forams in the sample from 1990? 7. What do your answers to Questions 4 -6 suggest about dissolved oxygen trends in the Chesapeake Bay and its tidal tributaries? 8. In what year was the salinity of the water unusually high? 9. What does this suggest about possible climate conditions during that time? Virginia’s Jamestown colony was founded in 1607 but nearly failed in 1609 and 1610 when the colony suffered an appallingly high death rate. One of the major factors affecting the region during those years was a period of severe drought during 1606-1612, documented in studies of tree rings. (The width of the tree ring indicates how much the tree has grown in a particular growth season: the wider the ring, the better the conditions for growth. As shown in the picture below, tree rings from 1606-1612 were narrower than average.) Droughts would have affected the colony's supply of food and clean water. 10. What would you expect to see in a core sample of benthic forams in the Bay or the tidal James from this time period? Jamestown Drought 1606-1612 Forays with Forams MathScience Innovation Center 2014 PAGE 4 DATA TABLE BENTHIC FORAMINIFERA IN TIDAL PATUXENT RIVER Ammonia parkinsonia YEAR # in Sample % of Sample Elphidium selseyense # in Sample % of Sample Ammobaculites crassus # in Sample 1990 1975 1965 1900 1850 1800 1750 Forays with Forams MathScience Innovation Center 2014 % of Sample