BY Nancy Biegel

www.owrb.ok.gov

academics.smcvt.edu

INTRODUCTION

The largest species in the ocean depend on the smallest for their survival. The base of any aquatic food web begins with those microscopic drifters, the plankton. Made up of free-floating organisms and weak swimmers, plankton move with the ocean currents and tides.

The phytoplankton, or microscopic plants, harvest the Sun’s energy to make food and oxygen. The microscopic animals, or zooplankton, feast on the phytoplankton and are in turn, eaten by larger and larger organisms. Without plankton, there would be no life in aquatic ecosystems.

WHAT IS PLANKTON?

The miniature world of plankton can be divided into three groups, phytoplankton, zooplankton and bacteria. Each has a niche in aquatic ecosystems.

projects.cwi.nl Phytoplankton, single-celled plants, are primary producers, or autotrophs.

They make their own food using light energy and produce 50% of the world’s oxygen, more than any other organisms.

One drop of water may contain thousands of phytoplankton.

The primary consumers of phytoplankton, and a vital link for larger organisms, are zooplankton.

Most are microscopic, but some, like jellyfish, can be much larger.

Zooplankton includes single-celled organisms, as well as fish & shellfish larvae, copepods, jellyfish and comb jellies.

Some are herbivores, predators.

while others are

www.in-fisherman.com

In aquatic ecosystems bacteria have the important job of decomposition. They feed on the remains of dead organisms, breaking them down and returning the nutrients back into a form plants can use.

Zooplankton and filter-feeders also feed on the bacteria.

COMMON PHYTOPLANKTON

commons.wikimedia.org DIATOMS Examine a sample of freshwater or saltwater and chances are, you’ll see diatoms.

They are the most dominant and efficient phytoplankton in any aquatic environment. They have cell walls called frustules which are made of silica. This allows light to pass through which is ideal for photosynthesis.

www.microscopy-uk.org.uk

DINOFLAGELLATES Another common dinoflagellates.

phytoplankton are the Most have two flagella to help them move up and down in the water column. They can be photosynthetic or parasitic, and a few can even produce their own light, called bioluminescence. These unicellular organisms are responsible for large algae blooms that happen during warm summers in coastal areas.

eol.org

COCCOLITHOPHORES These are an important source of food for aquatic ecosystems.

Plates of calcium carbonate make up their outer covering.

When the organism dies, the plates contribute to ocean sediments such as limestone.

2013 CMARS Teachers. Photo by Kathy Richardson.

COMMON ZOOPLANKTON

COPEPODS An important consumer of phytoplankton, copepods are tiny crustaceans and are the most numerous multicellular animal on Earth. They are a critical link between the autotrophs and the larger organisms in aquatic food webs.

IMPORTANCE OF PLANKTON

“Plankton are among the most important organisms on Earth, without which most life would die.” ~Life on an Ocean Planet Plankton are critical to the health of the complex food webs of all aquatic ecosystems. From oxygen production to carbon fixation, and production of food, plankton, the smallest of organisms, is the organism we can’t live without, even on land.

www.theseashore.org.uk

www.teachoceanscience.net

FISH & SHELLFISH LARVAE Many larger organisms, such as crabs, oysters, and finfish, begin their lives as plankton. In the plankton stage, they may look nothing like their adult forms.

www.fiu.edu

Callinectes sapida - Blue crab zoae.

dnr.maryland.gov

Fish eggs.

climatesight.org

earthdata.nasa.gov

www.chesapeakebay.net

PROTOZOANS Ciliates, radiolarians, foraminiferans, and other species come in different shapes sizes with and special adaptations that help them stay afloat. Some have skeletons of silica while others are made of calcium carbonate .

CTENOPHORA & CNIDARIA Comb jellies, the ctenophores lack the stinging cells of the cnidarians. Their cilia show a rainbow effect when they move, caused by diffraction.

The jellyfish, or cnidarians, catch their prey with stinging cells called nematocysts.

Both phyla are weak swimmers which puts them with the plankton.

RESOURCES

• • • • •

Textbook: Life on an Ocean Planet www.chesapeakebay.net

education.nationalgeographic.com

Background photo: www.coexploration.org

Copepod photo: academics.smcvt.edu

CREST

CREST-CISCEP (Center for the Integrated Study of Coastal Ecosystem Processes) is a NSF grant funded program at UMES aimed at exposing students, especially those from under represented populations, to the marine sciences through summer internships, paid undergraduate and graduate level assistantships and K-12 outreach activities.

CREST-CISCEP creates an educational and financial pipeline through which scientifically inclined students can travel as far as a Ph.D.!

ACKNOWLEDGEMENTS

Dr. Andrea Johnson, CISCEP Associate Director Dr. Paulinus Chigbu, CISCEP Director Kerrie Bunting Program Coordinators Christopher Daniels, CISCEP Boat Captain Dr. Eric May Faculty Mentors: Dr. Joseph Pitula Dr. Madhumi Mitra Dr. Patricia Goslee Dr. Yan Waguespack And all of the students who assisted with the program.