Marine Organisms & Ecosystems

HELL

Algae

-O2 photosynthesis
-Store C
-Non vascular
-Unicellular + Multicellular

Macroalgae

-Macroscopic
-Multicellular

Seaweed

Macroalgae growing in shallow marine environemts

Chlorophyta

Green algae

Rhodophyta

Red algae

Phaeophyceae

Brown algae

Thallus (Seaweed)

body of seaweed

Blades (Seaweed)

Leaflike structure, most photosynthetically active

Pneumatocysts (seaweed)

Gas filled structures that provide support and buoyancy

Stipe (Seaweed)

Stem like structure that provides support. Not very photosynthetically active

Holdfast (Seaweed)

Fixes thallus to the substrate, not found in all

Filamentous Internal (Seaweed)

Uniserate \= 1 row of cells
-Enteromorpha

Multiserate \= 2+ rows of cells
-Sphacelera

Coenocytic/Siphonous (Seaweed)

Multinucleated unicellular cells
-Bryopsidales

(Pseudo)Parenchymatous (Seaweed)

Aggregations of interwoven filaments
-Macrocystis

Polysiphonous (Seaweed)

Well branched algae with axial cells surrounded by 4 pericentral cells
-Polysiphona

Cortification (Seaweed)

Elaboration of polysiphonous condition, pericentral cells continue to proliferate

Enables flexibility

Filamentous External (Seaweed)

Non branching
-Chaetomorpha

Branching
-Cladophora

Sympodial Branching

Main axis does not extend via continuous growth

Monopodial Branching

Distinct main axis of continuous grown and gives of branchlets

Geniculum

Flexible joint on blade

Rhodophyte Diversity

Pigments
-Chl a, phycoerythrin, phycocyanin, b-carotene, xanthophylls

Cell Wall
-Cellulose, Agar, Carrageenan

Reserve
-Floridian starch

Form
-Unicellular (Rhodella)
-Multicellulsr
-Calcerous (Corallinales)

Rhodophyte Sexual Reproduction

1. Male + female gametes (n) fuse producing zygote
2. Mitotic division of zygote produces carposporophyte (2n)
3. Mitotic division of carposporophyte (cytocarp) produces carpospores
4. Carpospore develops into a tetrasporophyte
5. Meiotic division of tetrasporophyte produces tetraspores
6. Tetraspores develop into gametophytes
7. Gametophytes produce male + female gametes (n)

Rhodophyte Asexual Reproduction

1) Algae sporophyte produces non-flagellate spores
2) Spores are released
3) Spores germinate into new organism

Rhodophyte Vegetative Reproduction

1) Algae fragments
2) Fragments grow into new organism

Chlorophyte Diversity

Pigment
-Chl a + b, xanthophylls

Cell Wall
-Cellulose

Reserve
-Starch

Form
-Unicellular, colonial + coenobia
-Multicellular

Chlorophyte & Phaeophyceae Sexual Reproduction

1. Male + Female gametes (n) fuse producing zygote (2n)
2. Mitotic division of zygote produces carposporophyte (2n)
3. Mitotic division of carposporphyte produces carpospores
4. Carpospores develop into gametophyte
5. Gametophyte produces male + female gametes (n)

Chlorophyte Asexual Reproduction

1) Zoospores are produced and released
2) Zoospore lands on substrate
3) Zoospore divides mitotically and produces new filament

Phaeophyceae Diversity

Pigments
-Chl a + c, fucoxanthin

Cell Wall
-Cellulose + alginates

Reserve
-Laminarina

Form
-Multicellular, complex

Phytoplankton

-O2 photosynthetic
-Unicellular
-Cannot counter the current

Phytoplankton Primary Productivity

-Main 1PP
-CO2 sinks
-Biogeochemical cycles
-Support food weba

Phytoplankton Ecology

Limited by Irradiance, nutrients, temperature and oceanographic processes

Irradiance (Phytoplankton)

-Light required for photosynthesis
-Excess light causes photoinhibition

Nutrients (Phytoplankton)

-Limited by nutrient availability

Redfield Ratio \= 106C:16N:1P

Temperature (Phytoplankton)

-20*C optimim
-5-6*C inc/dec decreases net productivity
-Warmer \= smaller cells

Oceanographic Processes (Phytoplankton)

-Abundance determined by microscale processes

Morphological Classification of Phytoplankton

Unicells
-Synechoccoccus

Filaments
-Planktothrix

Coenobia
-Scenodesmus

Mucilaginous Colonies
-Eudorina

Cyanobacteria (Phytoplankton)

-Mostly aquatic, photosynthetic prokaryotes
-Unicellular, filamentous + mucilaginous colonies
-Many diazotrophic

-Main role in great oxygenation event
-Endosymbiosis

Diazotrophic

Capable of nitrogen fixation

Prochlorococcus (Phytoplankton)

-Most abundant group
-Populations depend on local environment + adaptations
-Efficient resource use + acquisition

Diatoms (Phytoplankton)

-Marine and FW, planktonic + benthic
-Silicified frustle with pores

Centric \= Radial symmetry w sap vacuole

Pennate \= Varied symmetry, with/without raphe, cytoplasm used for movement

Dinoflagellates (Phytoplankton)

-Unicellular, some colonial
-Marine + planktonic, some benthic, some FW

-Oxygenic autotrophs, mixotrophs, heterotrophs + parasites

-Many toxic (Bioaccumulation causes shellfish poisining)
-Bioluminescent

Coccolithophores (Phytoplankton)

-Unicellular algae
-CaCO3 scales called coccoliths

Coccolith accelerates photosynthesis, protect from photodamage + predators

Algal Blooms

-Rapid increase in density of a dominant group (1000 cells/ml)
-Caused by added nutrients/inc temp

-Causes anoxic conditions, can be toxic

Biotechnology (Phytoplankton)

-Environmental remediation
-Biofuels
-Food
-Biopolymer + Bioplastics

Zooplankton

Micro/macroscopic, phagotrophic organisms that cant counter the current

-Structures phytoplankton communities

Holoplankton

organism that live their entire life cycle as zooplankton

Meroplankton

organisms that are only planktonic for part of their life cycle and then become nekton

Copepods (Holoplankton)

-Aquatic crustacean
-Cosmopolitan distribution
-Parasitise all groups of animals
-Diocious, internal fertilisation

-Main secondary producer

Cosmopolitan Distribution

found almost everywhere in the world

Krill (Holoplankton)

-Swarming Crustacen
-Major biomass contributor in polar regions
-Major carbon sinking role in atlantic/southern ocean

-Secondary producers

Rotifers (Holoplankton)

-50um to 2mm
-~1000 cells
-Filter feed using corona (Herbivores + Omnivores)
-Planktonic/Sessile, some colonial

-Dioecious, internal fertilisation
-Sexual/parthenogenesis

Chaetognath (Holoplankton)

-Cosmopolitan distribution
-2-120mm
-4-15 hooked spines around mouth (Carnivorous)

-Hermaphroditic, internal fertilisation
-Planktonic eggs, develop in sacs/epiphytic

Pteropods (Holoplankton)

-Gastropods
-Swim using parapodia

-Shelled (Thecostomata)
-Naked (Gymnostomata)

Gelatinous Zooplankters (Holoplankton)

-Zooplanktons that are 95% water
-Scyphozoa/Ctenophores/Tunicates

Foraminifera (Holoplankton)

-Microzooplankter
-Unicellular Ameboid protist
-Calcerous cover
-Detritivores, omnivores + herbivores

Radiolaria (Holoplankton)

-Microzooplankter
-Unicellular Protist
-Silica skeleton around cytoplasm
-Herbivores, mixotrophs

Merozooplankton (Meroplankton)

-Crustaceans
-Molluscans
-Polychaets
-Fish
-Echinodermata

Diel Vertical Migrations (DVM)

Daily vertical migration of zooplankton from surface to deeper water during the day (10'scm - 100'sm) to avoid UV damage/Predation

-Circadian rhythm

Seasonal Vertical Migrations

Deeper water serves as a refuge

Nekton

Organisms that are able to swim against the current

-Pelagic
-Epibenthic/demersal

Pelagic

Organism living within the open ocean

Epibenthic

Organism living on the surface of the seabed.

Cephalopod Molluscs (Nekton)

Pelagic \= Squid, Cuttlefish + Nautilus
Benthic \= Octopus

-Tentacles
-Active predators
-Highly evolved nervous system
-Largest invertebrates

Cartilaginous Fish (Nekton)

Pelagic \= Sharks (Torpedo shaped)
Benthic \= Sakes, rays (Dorsally flattened)

-Cartilage skeleton
-Oily liver/fins for lift
-5 visible gill slits

Bony Fish (Nekton)

-Bony skeleton
-Most successful vertebrate
-4 gill arches + operculum7
-Swim bladder

Marine Reptiles (Nekton)

Sea turtles + snakes, marine iguanas + crocodiles

-Ectothermic
-Scaly
-Lungs for breathing
-Salt excretion glands

Marine Mammals (Nekton)

Carnivora, Sirenia, Cetacea

-Hair
-Mammary glands
-Endothermic
-Streamlined
-Lungs for breathing
-Modified respiration

Cetaceans (Nekton)

Porpoises, dolphins, whales (Toothed + Baleen)

-Echolocate

Baleen

filter feeding mechanism in whales

Echolocation

Sensory system in Odontoceti (toothed whales)

Carnivora (Nekton)

Seals, sea lions, walruses, sea otters, polar bears

-Hair
-Mammary glands
-Endothermic

Sirenia (Nekton)

Manatees, dugongs

-Herbivores

Buoyancy (Nekton)

-Gas/swim bladder (most)
-Air sacs
-Lungs

-Replacing heavy Na+ -\>with lighter NH4 in squid
-Lay down fats in fish/marine mammals

Physostome

Gas bladder with open duct between gas bladder and oesophagus

-Herrings, salmonids, catfish

Physoclist

No duct present on gas bladder

-Spiny-rayed fish

Hydrodynamic Buoyancy

-Lifting surfaces in anterior regions (Pectoral fins, flippers)
-Heteroceral tail

Heteroceral Tail

Upper lobe of tail is larger than lower lobe

Locomotion (Nekton)

-Undulation of body (side to side in fihs, up and down in cetaceans)
-Undulation of fins (glide strokes)

Frictional Resistance

Drag is proportional to the amount of surface area in contact with water

Form Resistance

Drag is proportional to the cross-sectional area of the object in contact with water

Induced Drag

Flow around small animls/slow large animals (slow

Streamlined Body (Nekton)

-Protruding structures recessed into depressions
-Non protruding eyes
-Reduced/absent scales
-Loss of hair/reduced length in mammals

Camouflage (Nekton)

Cryptic Body Shape
-Ventral keel

Cryptic Colouration
-Dark blue/green on dorsal surface
-Complex patters to mimic wave roughened surface

Ventral Keel

Row of raised scales along the ventral portion of the body

Schooling

Many individuals manoeuvring as one to reduce predation

Migration

Integration of reproductive cycle of adults + seasonal variations in patterns of primary productivity

Lateral Line System

Sensory mechanoreceptor system which detects movement/pressure changes

Ampullae of Lorenzini

Sensory organ which detects minute electric currents

-Sharks and Rays

Meiofauna

Organisms inbetween microbes and macrofauna

-62-500um
-Live in/on sediment
-Millions per square meter

Factors Affecting Meiofauna

-Sediment size + distribution
-Temperature
-Salinity
-Light
-Water movement

Nematoda (Meiofauna)

-Most abundant
-Found in sand, important in mud

-Tough cuticle
-Many feeding mechanisms
-Sticky secretions

Copepoda/Harpactacoida (Meiofauna)

-Second most abundant
-Short antennae
-Soft sediment
-Detritivores

Tardigrada (Meiofauna)

-Sand

-Tough cuticle
-Moult cycle
-Claws/toes

-Marine is dioecious

Kinorhycha (Meiofauna)

-Mud with high organics
-Found in oxygenated layers

-Eversible spherical head
-Segmented
-Spiny

Gastrotricha (Meiofauna)

-Interstitial in detritus rich sand
-Smallest metazoa

-Gliding cilia on side
-Bony spines + haptic tubes

Interstitial

Lives between sediment grains

Gnathostomulida (Meiofauna)

-Hypoxic, sulfidic, detritus rich soil

-Tripoblastic
-Bilateral
-Unsegmented
-Acoelomate
-Incomplete gut
-Unique jaw apparatus

-Hermaphrodites

Loricifera (Meiofauna)

-Deep sea sand and mud

-Bilateral
-Unsegmented
-Neck and thorax retractable into abdomen
-No respiratory organs

-Dioecious

Thiobiotic

Sulfur rich environment

Benthos

Organisms that live attached to or near the ocean floor

-Intertidal
-Subtidal
-Bathyal
-Abyssal + Hadal