Marine Biology Field Trip Plankton Sampling Introduction To fully appreciate the complexities of marine ecosystems and their food webs we should examine the often-overlooked organisms of the plankton. Plankton is simply defined as organisms that are at the mercy of the ocean's winds and currents. These organisms have limited powers of locomotion. One common misconception is that plankton must be microscopic. It is true that most of what we will examine on this field trip will be viewed with the use of a microscope, but there is plenty of macro plankton. The Portuguese Man-O-War responsible for a painful sting is an example of large plankton. Plankton can be classified into two different types: phytoplankton and zooplankton. Phytoplankton is the base of many marine ecosystem food webs and vitally important. This assemblage of organisms is analogous to plants and grasses of terrestrial habitats. By definition, phytoplankton is considered autotrophic - they create energy through the process of photosynthesis. Chlorophyll is the crucial pigment necessary for photosynthesis to occur. Just as most terrestrial vegetation contains green chlorophyll (giving them a green color), phytoplankton contains chlorophyll of varying colors. For example, the much-publicized Red Tides are toxic dinoflagellates that contain red chlorophyll. When conditions are right, these microorganisms can bloom and occur in such densities that they turn the water red. On our field trip today, the most common phytoplankton representative will be diatoms. It should be re-emphasized that phytoplankton is the base of marine ecosystem food webs. Again, just as terrestrial plants and grasses have animals which graze upon them, phytoplankton provides sustenance for our next group, zooplankton. Zooplankton is considered heterotrophic - they obtain energy by eating other organisms. For example herbivores eat autotrophs and carnivores eat other heterotrophs. The zooplankton community is extremely diverse, every known phyla is represented. To appreciate this assemblage, we need to further classify zooplankton into two groups: holoplankton and meroplankton. Holoplanktonic organisms spend their entire existence drifting in the plankton; they are created and die in the planktonic community. Holoplanktonic examples include diatoms (phytoplankton) and copepods (zooplankton). Copepods are analogous to insects in their abundance; some scientists believe they are the most abundant animals on earth. These will be the most numerous specimens we see on our field trip. Copepods are important for another reason; they are the primary grazers of phytoplankton and therefore are another important link in marine food webs. Meroplanktonic animals spend only part of their lifecycle drifting in the plankton. This is usually a developmental period typically called larvae. These larva are unique, since they do not resemble the adult and require metamorphosis when they reach a suitable habitat. As mentioned earlier, nearly all phyla are represented as meroplankton and a single species can have multiple larval stages. Examples include the developmental stages of fish, and countless species of benthic invertebrates (worms, clams, crabs, etc.). Below is a table to summarize the differences between holoplankton and meroplankton. Holoplankton Spend entire life in the plankton Examples: copepods, and diatoms Meroplankton Spend only part of life in the plankton Examples: fish and invertebrate larvae Plankton Collection Plankton has been collected in the same manner for years - through the deployment of nets. Like most sampling gear, there are different types for various purposes. First, plankton nets can have an assortment of mesh sizes expressed in microns (1 m = 0.001 mm.). Typically, smaller mesh sizes are used to collect phytoplankton, and larger mesh sizes used for various sizes of zooplankton. Neuston nets are rectangular plankton nets towed half in-half out of the water, and collect organisms in the neuston layer (the top meter of the water column). On the DAN MOORE we will deploy a tucker trawl, which is a multiple net gear. When the trawl is deployed, one net is positioned open; once it has completed fishing, a messenger is sent to close the net. The trawl is then moved to a different depth and an additional messenger deploys the second net. For this field trip we will use a single opening plankton net. We will attach a planer so the net will fish deeper in the water. Regardless of the net type, plankton nets should be towed from the side of a ship whenever possible. When dragged off the stern of a vessel there is the possibility of prop wash interfering with the net. Goals On this trip you'll have an opportunity to view a host of marine plankton sampled from the Cape Fear River. We will have several dissection microscopes to view the collections. Unfortunately, there will not be enough scopes for everyone, so you will have to share. Please view and draw several specimens and then give other students a chance while you attempt identification using the field guides provided. Attached to this lab are identification boxes for your drawings. The grading for this lab is as follows: A - 6 drawings and identifications B - 5 drawings and identifications C - 4 drawings and identifications D - 3 drawings and identifications F - 2 or less drawings and identifications Extra space has been added for additional information (Class, Order, Family, Genus, Species), if it can be ascertained. If the review questions are not complete, one letter grade will be subtracted from your lab grade. Complete sentences are required. Drawings are required to be as detailed as the following: Barnacle Larvae Cydippid Calanoid Copepod Crab larvae Megalop Medusa Zoea Crab Larvae Mysid Shrimp R/V MARTECH I ESTUARINE / NEAR SHORE RESEARCH VESSEL The R/V Martech I was acquired from Federal Surplus in December of 1994. Beginning in January 1995 the vessel underwent a complete overhaul and conversion into a research vessel. The conversion was a school project involving the Marine Technology program students and staff as well as students in several other programs (welding, electrical, machining, engineering and boatbuilding) at CFCC. DESCRIPTION: SPECIFICATIONS 53’ welded aluminum catamaran 17’ beam 34 gross tons, 27 net tons 4’ draft PROPULSION: Twin Detroit Diesel 671’s Cruising Speed - 10 knots FUEL CAPACITY: 720 gallons ELECTRICAL: 15 KW generator for AC power 12 VDC system Clean power for computers & electronics EQUIPMENT: Compass GPS DGPS Radar VHF w/ hailer & intercom Digital & paper fathometers Meteorological system Cellular phone WINCHES/DECK GEAR: Anchor windlass Stern deck capstan Hydraulic trawl winch, “A” frame & light duty davit FACILITIES: Interior is heated & air conditioned 150 sq ft Interior lab space [10’ x 15’] 180 sq ft Bow work deck [1l’x17’] 300 sq ft Aft work deck [18’xl7’] Small refrigerator Microwave Head. No shower facilities CAPACITY: 20 passengers