Plankton and Plankton Communities MARE 444 Lecture 1

Plankton Nekton - Move against prevailing water currents Plankton - Free floaters of the world Phytoplankton - Free floating plants, primary producers Bacterio - Free floating bacteria Viro - Free floating viruses Myco - Free floating fungi Zooplankton - Free floating animals (herbivores & carnivores) Proto - Free floating single-celled animals Meta - Free floating multi-cellular animals

Terms and Size Classes Meroplankton -Part-time free floaters e.g. crustacean, fish larvae Haloplankton -Free float entire life e.g. diatoms, copepods, ctenophores

Megaplankton Macroplankton Mesoplankton Microplankton Nanoplankton Net Plankton Microplankton Nanoplankton “Microbial Loop” Picoplankton

Phytoplankton Diatoms Dinoflagellates Coccolithophores Silicon dioxide glass “pill boxes” (single & chains) Dominate coastal waters (cold waters) Planktonic & benthic Coscinodiscus Chaetoceros Dinoflagellates No external skeleton of silicon Mostly solitary (chains rare) Photosynthetic, parasitic, grazer, symbiotic Proportions increase offshore; blooms Ceratium Peridinium Coccolithophores Tropical, pelagic CaC03 plates Coccolithus

Phytoplankton Cyanobacteria “blue-green algae” dominate brackish, nearshore waters often undergo nitrogen fixation N is converted to NH4+ Tricodesmuim Silicoflagellates unicellular and biflagellate chloroplasts, internal silica skeleton less abundant than diatoms high in Antarctic and open ocean Isochrisis Chlorophytes true green algae rare in marine waters often dominate estuaries and lagoons Chlamydomonas colony

I’m Spatial

The Temp

Life in the open ocean: sinking in the drink! A particle will remain suspended in seawater: Less dense than seawater Shape that  drag It can swim Water turbulence keeps it suspended Density of most plankton > seawater…..sink! Negative effect: beneath light penetration (photosynthesis) Positive effect: nutrients (regulate biochemcial composition

Staying afloat Principles of density and viscosity: Water density a function of: Temparature & Salinity Viscosity as Temparature and Salinity Principal of shape: objects of ~ weight but different shapes fall at different rates; fall rate related to the amount of resistance shape offers More surface area ~ more resistance to sinking Surface area increases as square of linear dimension of the object

Buoyancy more important in areas of higher temp and salinity Smaller objects with same shape have larger SVR

Reducing Density Change composition of body fluids replace heavy ions with light ions (= solute conc) NH4Cl (ammonium chloride) Physalia Gas-filled floats (gas < water) Excess food as oil droplets under carapace Incorporate low density body fluids Oils & Fats (food reserves)

Surface Area To Volume Ratio

Reducing Surface Resistance Small body size = (high SVR) Change shape….flatten or add spines/body projections Small size….more important in tropics???

Floating and Water Movement Day Night Surface waters Heats Cools Alternating heating/cooling--convection cells Langmuir Convection Cells Creation of vortices caused by wind driven movement Wind induced Plankton may be caught in convergence zones Small units of water either sinking or rising

Patchiness of the Plankton Plankton are extremely patchy…more frequently together than expected by chance Net tow 1 2 3 4 Why? 1) Spatial changes in physical conditions (T, S, Light) 2) Current transport & water turbulence (Langmuir converg) 3) Grazing activity (or lack of) 4) Localized reproduction 5) Social aggregating behavior (Deep scattering layer)

Patchiness of the Plankton However…difficult to quantify Net tow 1 2 3 4 Result 1 2 3 4