Deep Sea Communities: Diversity of the Deep A Classroom Activity for Ocean Gazing Episode #29: A 60-ton wakeup call

Written by: Breea Govenar, Woods Hole Oceanographic Institution Edited by: Lisa Lawrence, Virginia Sea Grant, Virginia Institute of Marine Science

Grade Level: 9-12 up images of Jules Verne’s giant octopus or even the recently caught colossal squid? In Lesson Time: 1.25 hr 1977, less than 30 years ago, scientists discovered communities of deep sea Materials Required organisms that are very different from these Ridge Excel datasheet giant monsters. While studying the ocean floor near the Galapagos Islands, scientists Summary happened upon hydrothermal vents Students calculate species richness, complete with their own assemblage of evenness and diversity for collections of organisms living on or around them. One of deep sea organisms using data collected the unique things about these communities from the Juan de Fuca Ridge in the Pacific is that food production is not based on Ocean. energy from the sun, but on energy from within the earth. In an effort to learn more Objectives about this unique environment and the extreme organisms inhabiting it, the ü Describe habitats, National Science Foundation established , and extremophiles. Ridge 2000, a research program that ü Recognize characteristics of a studies the links between the biology and community and evaluate deep sea geology of these ecosystems. community biodiversity. ü Analyze and calculate indices of Typically, animals that live on the bottom of the ocean are small and sparsely distributed diversity in deep sea communities. in thick sediment, but at mid-ocean ridges, many of the resident animals are large and Vocabulary cluster around cracks in the rocky substrate. Abiotic environment, Biotic environment, Some of these cracks are on the ocean floor; Diversity, Evenness, Richness, Species others are along sides of walls or chimney- like structures. Percolating or diffusing Introduction from these cracks are heated fluids that Do the words “deep sea creature” conjure have high concentrations of reduced

chemicals and heavy metals. Areas where species), species evenness (the number of hot, mineral-rich fluids escape the seafloor individuals per species), and species are known as hydrothermal vents. diversity (a combination of the species richness and evenness). The number of Hydrothermal vents are one of the most species in a community is always fascinating and challenging places to study considered to be the species richness, ecology. The variation in temperature and however different scientists and chemistry in this environment makes it mathematicians have used different uninhabitable to most organisms; however, formulae to calculate species evenness and a unique assemblage of animals has been diversity. The most common indices are discovered to thrive here. Extremophiles Pielou’s species evenness and Shannon- like these organisms are able to survive Wiener’s species diversity. To understand under environmentally extreme conditions. how animal communities respond to the The chemicals in the hydrothermal fluid highly variable environment at react with the overlying ocean water, and hydrothermal vents, it is important to first bacteria use the energy from this chemical determine the composition and the reaction to make food, in a process called structure of the different types of chemosynthesis. The food that the bacteria communities, including the species make is eventually assimilated, or taken up, richness, evenness and diversity. by all of the species at hydrothermal vents. Among the organisms that live in this extreme environment are tubeworms, Data Activity polychaete worms, gastropods (limpets & Pre-Activity Discussion snails), and pycnogonids (sea spiders). An assemblage of organisms can be described as a community. Just as you Unlike areas of high species diversity like might describe your community in your tropical rainforests and coral reefs, hometown, ecologists use statistics to hydrothermal vents are typically described characterize communities and track their as having low species diversity. Although changes over time and space. there are many organisms found at these vents (particularly in comparison to the ü In general terms, how would you bare rocks on the surrounding young sea describe your community (or floor), the number of different species is low neighborhood) in your hometown? and not all of the species coexist all of the What kind of statistics or indices would time or in all areas. In the following data you use to describe it? activity, we will use a number of methods to ü Does one household accurately examine the species assemblages found at a represent the overall community? hydrothermal vent. ü How does your community differ from another community in another town? Ecologists use statistics or indices to ü How would your community change if a examine patterns in the different new company built a large factory in assemblages of organisms. A group of your town? organisms that live in a particular area or have a similar lifestyle is often called a community. Some of the indices used by ecologists to characterize communities include species richness (the number of

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Hydrothermal Vent Organisms (click here for the classification tree of these organisms) Tubeworms Ridgeia piscesae Paralvinella palmiformis Sessile Polychaetes Paralvinella pandorae (worms) Paralvinella sulfincola Amphisamytha galapagensis Lepidonotopodium piscesae Branchinotogluma sandersi Mobile Polychaetes Branchinotogluma grasslei (worms) Branchinotogluma hessleri Opisthotrochopodus tunnicliffeae Lepetordilus fucensis Gastropods Depressigyra globulus (limpets & snails) Provanna variabilis Pycnogonids Ammothea verenae (sea spiders)

Data Activity & Discussion Shannon-Wiener’s species diversity In September 1999, a deep-sea sampling index (H’) and Pielou’s species evenness device was used to collect five different (J’). assemblages of animals from one sulfide 2. From Column A, count the total number edifice in the Main Endeavour Field of the of species for your collection. This is Endeavour Segment at the Juan de Fuca the Species Richness (S). Enter this Ridge (NE Pacific Ocean). The samples value in the cell for S. (Remember if the were brought back to the lab, sorted by number of individuals found for a species, identified and counted. All of the species is zero, then do not include this different species and the number of species in the total species count.) individuals of each species are listed in an 3. From Column B, total the number of Excel table. Using these data, determine individuals for all species. Enter this species richness, evenness and diversity for value in the cell for Total Number of each of the five samples. Individuals (N). 4. For Column C, calculate the Relative Divide the class into five groups and assign Abundance (Pi) for each species and each group one of the collections. Using the enter the values in the corresponding steps below, have each group calculate cells. To do this, take the number found species richness, evenness and diversity for for that species (Column B) and divide it their collection. Compare results for the five by the Total Number of Individuals (N). collections and answer the discussion Repeat for each species. questions. 5. In Column D, take the natural logarithm of the Relative Abundance (Column C). Calculating Diversity Repeat for each species. 1. Access the Ridge Excel datasheet. For 6. In Column E, multiply the Relative each sample there is a list of species and Abundance (Column C, before the abundance (number) of each species rounding) by the natural logarithm of found. There are also three empty Relative Abundance (Column D, before columns, for which we will calculate rounding). Repeat for each species. values that will be used to determine

Diversity of the Deep Page 3 7. Add all of the numbers in Column E and Related Resources multiply by -1. This is the Shannon- General , Biodiversity, Molluscs, Wiener Index of Diversity (H’). Deep Sea Enter this value in the cell for H’. 8. Divide the Shannon-Wiener Index of Diversity (H’) by the natural logarithm References of Species Richness (S). This is the “Habitats: Hydrothermal Vent Pielou’s Species Evenness (J’). Characteristics.” Office of Naval Research. Enter this value in the cell for J’. http://www.onr.navy.mil/focus/ocean/habi Compare your values to the answer tats/vents1.htm sheet.

“Creature Features.” Extreme 2004: Discussion Questions Exploring the Deep Frontier. http://www.ceoe.udel.edu/extreme2004/cr ü Which sample had the highest species eatures/index.html richness? ü Which sample had the highest species Ridge 2000. http://www.ridge2000.org/ evenness? ü Which sample had the highest species “Fauna.” Ocean AdVENTure. diversity? http://library.thinkquest.org/18828/data/f ü What are the advantages and auna.html disadvantages of using species richness, evenness and diversity to describe the “Extremophiles.” Seafloor Science. National structure of different communities? Science Foundation. ü Did the sample with the greatest http://www.nsf.gov/news/special_reports/ number of species (species richness) sfs/index.jsp?id=life&sid=ext also have the highest species diversity? Why not? “Tubeworms.” EXTREME 2003: To the ü Choose the two collections with the Depths of Discovery. highest diversity, and plot relative http://www.ceoe.udel.edu/extreme2003/cr abundance. Look at the top four eatures/tubeworms/index.html dominant species. Are they the same in each collection? If not, what’s different? Sarrazin, J., V. Robigou, S.K. Juniper, and Can you think of reasons why they J.R. Delaney. 1997. Biological and would be different? geological dynamics over four years on a high-temperature sulfide structure at the Juan de Fuca Ridge hydrothermal Data Source observatory. Marine Ecology Progress Govenar, B.W., D.C. Bergquist, I.A. Urcuyo, Series 153: 5-24. J.T. Eckner & Fisher C.R. 2002. Three Ridgeia piscesae assemblages from a single Sarrazin, J. and S.K. Juniper. 1999. Juan de Fuca Ridge sulphide edifice: Biological characteristics of a hydrothermal structurally different and functionally edifice mosaic community. Marine Ecology similar. Cahiers de Biologie Marine 43:247- Progress Series 185: 1-19. 252.

Diversity of the Deep Page 4 Stiling, P. 1999. Ecology: theories and applications. (3rd ed.) Upper Saddle River, NJ: Prentice-Hall, Inc.

Ocean Gazing Podcast The related podcast episode for this activity can be found by going to the podcast section of www.oceangazing.org

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