OCEA 1010A-Lab-Phytop-Primary Productivity (Phytoplankton) Lab

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Primary Productivity (Phytoplankton) Lab Before Coming to Lab: Read Chapter 13 (387-424) in Thurman & Trujillo, 11th ed. The purpose of this lab is to familiarize you with the spatial distribution ... of phytoplankton using satellite images and to examine its causes. In other words, you will learn where the tiny algae at the bottom of the ocean food chain like to live and explain why they like to live there. About Phytoplankton Phytoplankton are tiny (one-celled) algae, plant-like organisms that use sunlight as an energy source to make their own food in a process called photosynthesis (“making with light”). To carry out photosynthesis, they need large amounts of water and the gas carbon dioxide, both abundant in the ocean, to make carbohydrates (the “food” molecules). Sunlight + Water + Carbon Dioxide Carbohydrates + Oxygen ("Sugars") They also need small amounts of nutrients, molecules that they use to build their bodies or molecular “tools” that are needed to carry out photosynthesis, but are not used up in the process. (A hammer is a tool that can be used in the process of building a chair, but the hammer is not part of the chair as the end of the process. It can be re-used again and again to build more chairs.) Examples of nutrients include nitrates, phosphates, and silica. Primary productivity is the rate at which “food” molecules (carbon compounds that chemically store the energy captured from sunlight) are created. The more phytoplankton that are present, the higher the primary productivity will be. Sunlight and nutrients are the hardest things for phytoplankton to obtain, so wherever there are both sunlight and nutrients, phytoplankton will be abundant. Animals will be attracted there too, because phytoplankton are at the bottom of the ocean food chain. In other words, animals in the ocean eat phytoplankton (e.g., zooplankton) or they eat other animals which eat phytoplankton. The phytoplankton make their own food, so we call them “primary producers:” they make (“produce”) organic material from inorganic material (carbon dioxide, water). This is the first or “primary” step in the food chain. Animals are secondary, tertiary, etc. producers depending upon their level in the food chain. They make the organic material of their bodies from organic material that they eat. Think of nutrients as “fertilizing” the phytoplankton. Nutrients are not “food” or “eaten” by phytoplankton. (Phytoplankton make their own food.) As you will observe under the microscope, phytoplankton have no tentacles, arms, or other structures with which to grab the extremely tiny nutrients. Instead they rely upon chance: the nutrients drift into their bodies through the holes in their shells or cell walls Name: Section: Due Date: Names of Group Members: 1. 2. 3.Lab 10A-2 Sunlight is, of course, most abundant at the top of the ocean. As sunlight goes downward through ocean water, it is absorbed by the water, warming the surface of the ocean but leaving the deep ocean cold and dark. Anything that helps phytoplankton float like unusually cold and salty water (high density water) at the surface of the ocean and upwelling (water moving upward from the deep to replace surface water pushed away by winds) leads to the growth of more phytoplankton. In fact, many phytoplankton are more dense than water (because of their hard calcium carbonate or silica shells), so they sink. They rely upon waves or other mixing mechanisms to bring them back up towards the sunlight at the surface. Their bodies are shaped so that they fall slowly, allowing them to wait for that lucky wave. There is at least one advantage to falling, though: their bodies are exposed to more nutrients. Nutrients enter the ocean when they are washed off the land by rain runoff. (The nutrients in soil allow plants to grow.) Thus, phytoplankton like to live near the coast, and nutrients are hard to find out in the middle of ocean. As dead organisms and wastes sink towards the bottom of the ocean, they are slowly decomposed by bacteria or dissolved by ocean water, releasing nutrients back into the water in the deep ocean. However, many nutrients are released too deep, where phytoplankton cannot live because of a lack of sunlight. Anything [Show More]

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