ENVS121 Lecture 1 Intro and Macroalgae PDF

Preview

Summary

Download ENVS121 Lecture 1 Intro and Macroalgae PDF

Description

Dr Rachel Jeffreys

Learning Objectives

ENVS121: Life in the Seas and Ocean

Welcome and Introduction Rachel Jeffreys

Format

• • • •

Schedule on VITAL Lectures (24) Three laboratory practical sessions & one fieldtrip Reading – Text books (next slide) – Scientific articles, web based resources (careful)

Learning styles - Lectures

Module Leader

Acquire knowledge and understanding on:

Module Team 1. The taxonomic diversity of marine life 2. The ability to recognise the major taxonomic groups 3. How to examine marine organisms and understand their functional biology in the laboratory and field 4. Recognition of the adaptational solutions to functional problems adopted by marine organisms

Dr Jon Green Prof. Claire Mahaffey

VITAL

Resources • An Introduction to the Invertebrates. Janet Moore. On Reading list • The Invertebrates: A Synthesis (e-book available) • The Invertebrates: A New Synthesis • Invertebrate Zoology. Ruppert, Fox & Barnes Basics if needed: • Biology, Campbell & Reece

Learning styles - Practicals & Field trip

Assessment

• Sessions are compulsory – attendance is monitored • We will not bring hand outs • Slides will be available on VITAL >24 hours in advance – print a copy & bring if you want to • You should make notes/ask questions • Lectures will be streamed afterwards so you can listen back/fill in gaps • You should build up a folder of notes for each taxon group covered (use in tests & through your degree…..)

• Introductory lecture, 10.00, Practical will start at 10.30 – 11.00. • Handouts and workbooks provided • Lots of finding out about animals and their form and function, drawing and describing (skills) • Complete guided exercises in the day and submit before you leave • Practical 1 = formative (not marked) • Practicals 2, 3 & field trip (P4) = summative (count towards your final module mark)

• Practicals 2 or 3 & field trip (P4) are assessed (40% overall) – testing knowledge and skills such as drawing annotated diagrams • Two online tests (see next slide, 60% overall) - testing breadth of knowledge and ability to find information • No formal exam after Christmas

Online tests

The Seas and Oceans

• There will be a short practice test available to try over weeks 4-6 (correct answers not important) Two summative online tests: • Test 1 (Week 7) = 30 MCQ questions in 60 mins (1 attempt) on content from lectures 1-13 (34%) • Test 2 (Week 12) = 25 MCQ questions in 50 mins (1 attempt) on content from lectures 14-23 (26%) • Tests are open book – can flick through notes • Can complete any time between 9-5 on Tuesday of test week • MUST complete on University networked computer

Order of groups covered

The tree of life. ENVS121 Life in the Seas and Oceans

• • • • • •

Bacteria and Plants (week 1-2) Invertebrates (weeks 2-7) Fish (weeks 8-9) Marine Reptiles (week 9) Marine Mammals (week 10) Birds (weeks 10)

• Practicals – weeks 2, 5, 6 and 11

Macroalgae

Each Phyla/phylum will cover…. • Key features – External morphology including size – Anatomical structure – Identification features • Why is this group successful – Feeding: how and on what? – Breeding: how? Life history – Life style: including habitats • Stories – examples - unique features

Autotrophic plants Make food from inorganic nutrients 1. Seaweeds 2. Sea Grasses

Seaweeds General Morphology

Lecture 1: Macroalgae Rachel Jeffreys

https://www.youtube.com/watch?v=ka0kyQ_AlL8

Usually connected to a substratum Take up nutrients from water Lack complex root structure and support structures required by terrestrial plants Grow up to light – some have gas filled floats

Key Features

Key Features

Individual attached seaweed is Thallus

Seaweeds Macroscopic photosynthetic algae: Free living or attached

Stipe – stem, tubular flexible Blade – light capture and photosynthesis Pneumatocysts - floats

Classified by: 1. Pigments 2. Storage products 3. Flagella in spores

Small seaweeds grow by cell division Large seaweeds specialized areas of cell division meristems

Macroalgae - Seaweeds 1. Chlorophyta Green: Chlorophyll a, b Use red and blue light 2. Phaeophyceae Brown: Chlorophyll c and fucoxanthin Use red and blue light (red more)

Group

Pigments

Storage Products

Cell Wall

Green algae

Chlorophylls a, b

Starch

Cellulose (not all)

Brown algae Chlorophylls a, c, fucoxanthin

Laminarin, mannitol

Alginate

Red algae

Floridian starch

Agar, carrageenan

Chlorophylls a, d, phycoerythrin, phycocyanin

Green Algae

Macroalgae - Seaweeds Some no more than two cells thick, others thicker Red brown and green seaweeds not closely related Seaweeds may be monoecious – hermaphrodites, or dioecious – separate sexes Many species of seaweeds show ‘alternation of generations’. Haploid gametophyte (sexual reproduction) alternates with a diploid sporophyte (asexual reproduction).

3. Rhodophyta Red: Chlorophyll + phycocyanin phycoerythrin Absorb blue light

Chlorophyta • • • •

Most are freshwater or terrestrial ~ 1000 marine species, most are unicellular, 110 UK Habitat gives important clues for identification A few species are very wide spread, especially in low or fluctuating salinity such as upper shore pools or if grazing is high e.g. Ulva, Enteromorpha

Use of light has implications for where they live Light penetration with depth

Green seaweeds life cycle and reproduction

Ulva life cycle and reproduction

Variety of complex life cycles: two major types

• Diploid sporophyte produces microscopic zoospores – 4 flagella • Zoospores can be liberated in large numbers

1. Gametophyte (sexual reproduction) and sporophyte stage (asexual reproduction) look the same (isomorphic) e.g. sea lettuce Ulva

• Zoospores settle after 1 hour of swimming and germinate to produce haploid gametophyte stage

2. Gametophyte phase is the recognizable seaweed and sporophyte phase is microscopic e.g. green tarantula weed (Acrosiphonia arcta)

Ulva life cycle and reproduction • Gametophyte stage –gametes 2 flagella produced by gametophyte plant released from gametangia • Diploid zygote produced by fusion of gametes. • Zygote germinates and produces diploid sporophyte. Ulva may also reproduce by fragmentation of broken parts of plant, which carry on growing.

Seaweeds of Britain and Ireland Bunker et al. 2017 2nd edition

Brown Algae

Brown Algae (Phaeophyta)

Phaeophyta • Contain Chlorophyll c and fucoxanthin • Brown colouration from xanthophyll and carotene • 1500 - 2000 species, nearly all marine, 185 UK species • Zone defining on rocky shores • Include the ‘Fucoids’, the ‘kelps’ and the invasive Sargassum

Alternation of generations: two phases in life history 1. Haploid gametophyte: produces gametes (sexual reprodn) 2. Diploid sporophyte: produces spores (asexual reprodn) Gametophyte and sporophyte look completely different e.g. kelps

The macroscopic kelps we see are the sporophyte phase and the gametophyte phase is a microscopic organism

Fucus life cycle and reproduction Male reproductive structures: Antheridiophores Branched, tree-like structures that line the conceptacles. They have terminal inflated antheridia on their branches, which undergo meiosis and form 64 to 128 biflagellate male gametes (antherozooids).

Fucus serratus life cycle and reproduction

Fucus life cycle and reproduction

Plants are always diploid and meiosis takes place before the gametes are formed. Gamete production takes place in specialized structures called conceptacles in swollen areas at the tips of the plants: called receptacles. Most fucoids are dioecious with each sex on different plants Fucus spiralis is monoecious with both sexes occurring on one plant. Here both sexes may be in one conceptacle whilst in others they may be in separate conceptacles.

Fucus life cycle and reproduction

Female reproductive structures: Oogonia Short stalks and after meiosis to form 8 nuclei (one meiosis and one mitosis) the oogonium then cleaves to form 8 large, nonmotile eggs. Gametes are usually released into the water on the rising tide.

Seaweeds of Britain and Ireland Bunker et al. 2017 2nd edition

Brown Algae Adaptations

Laminaria life history

• Intertidal organisms must resist desiccation • Thick, leather cell walls and production of mucilage help prevent water loss. • Habit of forming clumps reduces evaporative losses • Many can lose a large amount of water but then rehydrate in minutes upon re-submergence • Grazing resistant – chemical defences and physical structure make it hard to digest

Laminaria

Seaweeds of Britain and Ireland Bunker et al. 2017 2nd edition

Red Algae Rhodophyta • Contain red accessory pigments: phycobiliproteins (e.g. phycoerythrin) • 7000 species, most marine some FW, 350 species UK • Not good at resisting desiccation – so lower shore, pools and sub-littoral • Some species deposit calcium carbonate in cell walls – ‘calcareous/coralline algae’, encrusting/erect, grazer defence, important for CO2 sequestration

Polysiphonia

Polysiphonia life history and reproduction

Reproductive structures: Male: spermatangia Female: Carpogonial Found in gametophyte plant. Gametophyte plant either monoecious or dioecious. Spermatangia release nonmotile spermatia into water and they fuse with carpogonia, zygote forms on female gametophyte.

Photosynthesis • Brown seaweeds can be very productive – kelp forests are extremely productive: – Laminaria 2,000 g C m2 y-1 – Macrocystis 5,000 g C m2 y-1 • Intertidal species often photosynthesise more when exposed than when submerged • Water and particles in the water absorb light – so less light at depth

Lomentaria

Carposporophyte has reproductive cells producing carpospores these settle to produce tetrasporophyte seaweed. Tetrasporophyte does not have reproductive structures, it geminates to produce gametophyte plants. Meiosis occurs as tetraspores are produced.

Seaweed Habitats: The intertidal

Most seaweeds are edible Significant consumption in Asia (China, Japan, Korea) Icelandic sagas from 10thC mention regulations for Dulse (Palmaria palmata: red algae) collection Used as an ingredient/additive in many processed foods – ice cream, chocolate... Agar Cosmetics Sea weed spa etc

Seaweed Habitats: Maerl beds

• Intertidal 35 000 km coastline • Regulated by tides • Upper shore immersed 20% of time, lower shore 80% of time • Period of emersion: spatial distribution of seaweeds on shore • Desiccation, inter-specific competition, grazing

• Red seaweeds harvest green and blue part of the spectrum by having red accessory pigments, but blue light lower energy than red

Edible Seaweeds

Lomentaria life history and reproduction

https://www.youtube.com/watch?v=ntayalN_2Ss http://www.nhm.ac.uk/discover/seaweeds-a-hidden-habitat-under-threat.html

Seaweed Harvesting http://www.acadianseaplants.com/marine-plant-seaweedmanufacturers/resource-management/seaweed-resource-science https://www.youtube.com/watch?v=adK-ViHNW_8

Seaweed Culture Mainly China and Japan Large scale – 9.5 million tonnes (fresh wt) per annum The kelp Laminaria japonica accounts for most of Chinese production (about 3.8 million t). The most valuable spp is the red alga Nori (Pyropia species, mainly P. yezoensis). Japanese production is worth about $US1 billion and Korean production about US$0.5 billion.

Sea Otters in Kelp

Sea Grasses: plants not seaweeds Higher flowering plants, simplified flowers Vascular transport system Nutrient uptake via porewaters, some species rhizomes have nitrogen fixing bacteria

https://www.youtube.com/watch?v=eYpM-qDNKzs

Sea Grasses

Sea Grasses

Geographic distribution: shallow temperate, subtropical and tropical waters Grow in shallow, quiet, subtidal soft bottoms Lost 35% of seagrass since 1980s

Tough - high cellulose content – difficult to digest - Eelgrass is indigestible Turtle grass can be eaten by urchins and turtles symbiotic gut microbes similar to cows!

Further Resources https://ed.ted.com/lessons/attack-of-the-killer-algae-eric-noel-munoz http://www.seaweed.ie Pollen transported by water

https://www.projectseagrass.org

Sea Grasses: Diversity...