Coral reef bio Flashcards
(178 cards)
1
Q
Coral reef Definitions
A
A pronounced physical and robust marine
structure that is predominantly composed of
calcium carbonate skeletons of coral and
associated species that is consolidated and that
provides habitat for many different species
* a ridge of rock in the sea formed by the growth
and deposit of coral
* Coral reefs are made up of colonies
of hundreds to thousands of tiny individual
corals, called polyps. These marine
invertebrate animals have hard exoskeletons
made of calcium carbonate, and are sessile,
meaning permanently fixed in one place.
2
Q
Coral reefs, despite their small
size (<0.1% of the ocean surface)
also provide habitat for at least
25% of all marine species, with
estimates of over one million
species living in and around coral
reefs (Census of Marine Life)
A
Coral reefs, despite their small
size (<0.1% of the ocean surface)
also provide habitat for at least
25% of all marine species, with
estimates of over one million
species living in and around coral
reefs (Census of Marine Life)
3
Q
Significance of reefs:
A
- Physical:
Coastline protection
Palaeoenvironmental data
- Productivity and diversity:
Sites of long-term marine biodiversity
Genetic/biological potential
e.g., AZT (HIV Treatment) – Caribbean sponge
- Economic:
Food – fishing – US $100m
* Construction materials
e.g., Maldives 111,000m3 coral mined over last 20 years
* Tourism/recreation
e.g., Caribbean – 100 million tourists/year - worth
US$10B
* Aquarium Fish Trade –
worth US$30-40M
Economic pressure + over-exploitation
leading to widespread degradation of
reef systems.
4
Q
What affects Coral distribution?
A
-Temperature - optimum 25-29oc
- Salinity - optimum 35o/oo
- Depth (light) (<100m) - optimum <20m
Define principle areas in which coral reefs exist + rates of coral growth
Also limited by:
* nutrient levels
* sediment
Natural sediment/nutrient
sources:
* Oceanic Upwelling
* Terrestrial Run-off
5
Q
The 4 different types of Reefs
A
Fringing reefs grow near the coastline around islands and continents. They are separated from the shore by narrow, shallow lagoons. Fringing reefs are the most common type of reef.
Barrier reefs also parallel the coastline but are separated by deeper, wider lagoons. At their shallowest points, they can reach the water’s surface forming a “barrier” to navigation.
Atolls are rings of coral that create protected lagoons and are usually located in the middle of the sea. Atolls usually form when islands surrounded by fringing reefs sink into the sea or the sea level rises around them.
Patch (or lagoon) reefs are small, isolated reefs that grow up from the open bottom of the island platform or continental shelf. They usually occur between fringing reefs and barrier reefs. They vary greatly in size, and they rarely reach the surface of the water.
6
Q
Why is knowledge of evolutionary history useful?
A
- Evolutionary history
and species
relationships? - Past environmental
conditions and
consequences - Drivers of speciation
and responses - Evolutionary
significance of
different taxa - Conservation value of
looking at the past
but also the future
7
Q
General Coral Biogeography Patterns
A
There are areas of high diversity in the tropical western margins of the worlds great oceans although the Indian Ocean is less defined
- Within the Indo-Pacific there is low generic variance – dispersion is high (or distribution is high)
- There is attenuation of species diversity latitudinally & longitudinally from these centres.
- Regions far away from the centres of diversity seemingly have similar species (Marginality and Sub-optimality)
- Latitudinal attenuations occurs at similar rates (i.e. increasing distances) in the Northern
and Southern hemisphere. - Latitudinal attenuation is highly correlated with sea surface temperature.
- The mean generic age of the Caribbean corals is twice that of Indo Pacific corals and
centres of diversity tend to have relatively younger generic ages.
8
Q
Why is the CIP (Central Indo-Pacific) so diverse?
Four Main Theories
A
The ‘centre-of-origin’ hypothesis states that more new species
originated in the CIP than surrounding regions
The ‘centre-of-accumulation’ hypothesis states that lineages
originating elsewhere preferentially colonized the CIP
The ‘centre-of-overlap’ hypothesis states that species have
widespread ranges that overlap in the CIP due to its central position
in the broader Indo-West Pacific
The ‘centre-of-survival’ hypothesis states that lineages in the CIP
experienced less extinction than those in surrounding regions
9
Q
What was Darwin’s theory on coral reefs?
A
Darwin also proposed a theory of how isolated rings of coral reefs, known as atolls, formed. He suggested that they originally grew around extinct volcanoes which then sank into the sea, leaving the reef as an isolated circle.
10
Q
What is the meaning of ecosystem services?
A
The value of nature to people has long been recognized, but in recent years, the concept of ecosystem services has been developed to describe these various benefits. An ecosystem service is any positive benefit that wildlife or ecosystems provide to people. The benefits can be direct or indirect—small or large.
11
Q
Examples of Coral reef Ecosystem Services and why they are important.
A
Coral acts as coastal protection and helps dissipate waves before they hit the shore.
Food and Fishing.
Medicine
There are 4 main services:
- Supporting services such as biodiversity benefit which is paramount since you need animals in the first place for the following services.
- Regulating services such as coastal protection. by dissipating up to 97% of energy that would otherwise hit shorelines.
- Next is provisioning and Fisheries which can of course provide food for people. Moreover, it gives anglers a sense of identity and culture.
- Finally, is cultural such as places like Hawaii being conically near the sea. Also things such as finding new compounds for medicine.
12
Q
Coral reef Importance lecture summary
A
Coral reefs provide important ecosystem services
* c.1 billion people living within 100 km of a coral reef and growing
* Coral reefs have more higher-level taxonomic diversity than
tropical rainforests
* Globally over 6 million fishers are dependent on coral reefs in 99
countries
* Total Social, cultural and economic value of coral reefs at US$1
trillion (in total Ecosystem service provision)
13
Q
Why Monitor Reefs?
A
Stock, status, management
effectiveness, impact assessments,
research, modelling and future
predictions, value assets. Political
decision making: local to global
14
Q
What is assisted evolution in corals?
A
The term ‘assisted evolution’ (AE) refers to a range of approaches that involve active intervention to accelerate the rate of naturally occurring evolutionary processes. These approaches aim to enhance certain attributes such as temperature tolerance, growth or reproduction.
15
Q
Dependant factors in the way of surveying reefs
A
There are a huge array of different techniques used by divers when surveying a coral reef and the techniques employed depends on:
- The aim of the study especially resolution, scale and accuracy
- The Site: reef types, spatial and temporal scales, access
- Resource availability e.g. time, equipment,
- Skill set of the assessors
16
Q
What are some different types of Environmental data you could get from the ocean.
A
-Depth
* Light attenuation
* Sedimentation
* Nutrients
* Productivity of water
* pH
* Temperature
THESE COULD BE AFFECTED BY SEASONALLITY
17
Q
Reef Assessment Techniques: Benthic
A
Spatial scales:
– Large global, national, regional
– Regional: low effort per sample unit but high cover
– Local: Greater accuracy but less area
What to survey?
- biodiversity, abundance, density, complexity, rates of change?
Examples: Remote sensing: Manta Tow: Restricted effort: Transects: Quadrats: colony
18
Q
Reef level assessment: low resolution and High resolution
A
Low resolution – high cover (benthic Mapping; rapid assessment; pre-assessment
High resolution - Transects: length dependent on habitat
quality, homogeneity, aim of study
* Point Intercept
* Continual Intercept
There is also AI software you can use that will identify different species in a photo.
19
Q
Benthic Categorisation
A
A number of categorises can be identified
Rock
Sand
Rubble
Water
Dead Coral
Algae
Soft Coral
Sponge
Other
Branching Coral
Encrusting Coral
Submassive coral
Tabulate Coral
Mushroom Coral
Massive Coral
Digitate Coral
Foliose Coral
20
Q
Fish Surveys techniques
A
Numerous techniques:
– Restricted effort
– Distance and time restricted belt transects
– Stereo-video transects
– Baited Cameras
– Acoustics
– Fisheries data!
21
Q
Fish productivity?
A
Estimated through standing stock or assessed through:
* Two ways:
– Light traps (especially for fish larvae)
– Plankton nets
– Must consider daily, tidal, lunar and seasonal cycles.
22
Q
Measuring Coral growth rates
A
Many different ways:
– Linear extension
– Changes to bulk density
– Changes to surface area
– Changes in volume
– Coring
– Calcification rates
23
Q
Summary of reef monitoring and network
A
Long-term monitoring of coral reefs can provide critical data that
help coastal residents and marine managing authorities understand
the health of the reefs
* Environmental data is necessary to understand (mostly) abiotic
factors
* Benthic reef assessment techniques and methods can be from (low
resolution) remote sensing to (high resolution) line intercept
transect
* Photogrammetry and AI – the future?
* Fish belt transects and productivity
* Coral recruitment and growth methods
* Carbonate budgets
* Global monitoring networks and data bases
24
Q
Info on Cnidarians
A
> 9000 species
* Mostly marine
* Four classes
1. Hydrozoa (polyp phase more
conspicuous)
2. Scyphozoa (true jellies – medusa
larger)
3. Cubozoa (polyp tiny)
4. Anthozoa (polypoid; no medusa
stage; some proliferate asexually
into colonies)
* Radially symmetrical
* Lack cephalization
* Bodies have two layers
* Saclike coelenteron has one
opening (mouth)
* Primitive- cells organized into distinct
tissues, lack organs
* 2 body forms – polyp and medusa
25
Coral Classification
Hermatypic corals are those corals in the order Scleractinia which build reefs by depositing hard calcareous material for their skeletons, forming the stony framework of the reef. Corals that do not contribute to coral reef development are referred to as ahermatypic species.
26
Coral anatomy: terminology
Corallite – skeleton produced by a single polyp
* Costa (pl. costae) – extension of the septa outside the wall
of the corallite
* Septum (pl. septa) – skeletal plates that radiate into the
oral disc
* Wall – corallite wall (theca)
* Palliform lobes – pillar like projections on inner margins of
septa
27
The live coral tissue: zooxanthellae
Zooxanthellae population in the gastroderminal tissue throughout the polyp; and in the
interconnection between neighboring polyps (coenosarc); extremely important and often
give coral their distinguishable colour
28
Coral Nutrition: Heterotrophy
Corals are carnivorous
* Tentacles (also sweeper tentacles)
* Nematocysts
* Mucus
* Cilia
* Paradox - not enough plankton to
support observed growth (5 - 10 %)
* But varies with species, available
particulates & Environment
* All corals have some ability to capture
prey specially at night
* Some corals better adapted
Reefs acclimated to turbid environments have a much greater
potential to sequester nutrients through heterotrophy: example
from the field
29
Symbiosis: Zooxanthellae 1/2
Up from 96% of food requirements
come from Zooxanthellae
But it does vary between
environments, species and time
Zooxanthellae found in corals,
molluscs, sponges, flatworms
They are small brown algae (1/10th
mm) that can be several million per
cm2
They are dinoflagellates that can live
inside and outside of corals
30
Symbiosis: Zooxanthellae 2/2
belong to a single family Symbiodiniacea
- seven genera and around 200 different
“species”
* enter the coral through the mouth and
enveloped in host tissue (Phagocytosis) –
forms the symbiosome (one cell)
* provide carbon for the coral and receive
nutrients from the coral host for growth
and reproduction
* drive coral growth through calcification
* Corals can survive without zooxanthellae –
depends on species and environment
31
Coral Photosynthesis
Corals produce CO2 and H2O as byproducts of cellular respiration
zooxanthellae use these for photosynthesis.
Sugars, lipids, and O2 (products of photosynthesis) – tight recycling of products driving force
behind coral and productivity
32
Zooxanthellae and translocation
Utilise CO2 and produce glucose
* This glucose can be used by the zooxanthellae
in several ways:
1. Zooxanthellae reproduction - Slow
growth rates (small)
2. Cellular respiration (small)
3. Translocation – Carbon not used for the
above is TRANSLOCATED to the coral host
in the form of glucose.
* Example of unbalanced growth –
photosynthesise x100 more than the
zooxanthellae needs
* Translocation controlled by nutrients provided
by host
* Host control factor
33
The coral holobiont
Zooxanthellae, endolithic
algae, bacteria, archaea,
viruses, fungi – all make up the
holobiont
* Changes to holobiont
represents changes to genetic
structure of the holobiont –
adaptation?
Factors controlling the
microbiome – host and
environmentally driven
34
The coral holobiont: healthy
Usually the microbiome plays positive role optimizing fitness in normal and stress
conditions
* The microbiome can respond rapidly to changing environments
* Some elements of the microbiome can even buffer impacts of environmental
change
35
The coral holobiont: unhealthy
Sometimes conditions or changes to the biology of the host, the microbiome
may get out of control, e.g. increased nutrients or new microbe introduced
through pollution can lead to disease and mortality
36
Summary for lecture 5 Heterotrophy and Photobiology
Corals belong to the Cnidarian Anthozoans, mostly to the order Scleractinia
* They are individual organisms living as a colony and through by products of
photosynthesis produce calcium carbonate skeletons
* Each coral poly sites in a coral cup called a corallite. This corallite is species specific (but
does alter with environment)
* All corals are carnivores but the level they depend on capture food depends on species
and environment
* Several food capturing mechanisms including stinging cells, tentacles cilia and mucus
* Key are zooxanthellae (7 genera and 200 species). They photosynthesize and provide
coral with 90% of food requirements in cases (glucose). The coral provides the
zooxanthellae with nutrients. The photosynthesis of zooxanthellae drives calcification
* Zooxanthellae can be passed from generation to generation through vertical
transmission or can be obtained from the environment via horizontal transmission
* Many other organisms make up the coral holobiont
* If conditions turn bad the microbial life on a coral can get out of control and cause
disease
* Generally very important for health and also may help corals survive stress
37
Corals: 10 basic facts
A Cnidarian belonging to the Scleractinian order of Anthozoans
2. The polypoid growth phase is dominant – larvae is medusa
3. Mostly colonial producing a hard skeleton
4. Generally exists in association with a number of microbes and
algae – the Holobiont
5. Algae termed Zooxanthellae – singular or many (210 sub-clades
of 9 clades)
6. A number of functional types – relate to growth form
7. Between 750-800 species of hard (hermatypic) coral species
8. Tend to depend mostly on autotrophy but are also heterotrophic
depending on species, environment and disturbance
9. Have a restricted global and local distribution
10. Are the key ecosystem architects but not the only reef builders
38
Coral growth cycle
Coral larvae (planula)
Searching
attachment
metamorphosis
primary polyp
juvenile coral
Adult coral
39
Coral settlement
Corals are sessile -> a good settlement spot is crucial.
Planula larvae use sensory cues to find the perfect spot
Settlement choice determined by abiotic and biotic factors.
Abiotic factors: Local currents, light intensity, hard substrate, sedimentation, temperature.
Biotic factors: Other corals (competition), Algae (can prevent settlement), bacterial biofilms, Crustose coralline algae (CCA) [metabolites induce settlement.
40
Competition between corals
Suitable space on reefs is limited resource
There is fierce competition among corals.
Comes in two basic forms:
Direct: digestive activity, overgrowth
Indirect: overshadowing, allelopathy
Outcomes depend on: Species morphology, growth rate, aggression ability, environmental conditions.
41
Calcification
Calcification: formation of organic matrix around which calcium carbonate is deposited
Corals can take up ions from surrounding water and turn them into calcium carbonate.
Process energetically costly -> energy provided in part by symbiotic algae
42
What is aragonite?
Aragonite is a metastable form of calcium carbonate that is precipitated biogenically by many reef forming corals and other species. The aragonite saturation state, Ωa, is commonly used to describe the ability of corals to calcify and is given by: where Ksp is the solubility product
43
Coral growth
During growth, polyps lift off their base and secrete a new one.
CaCO3 (calcium carbonate) deposition leads to elevation of the coral tissue.
Coral growth consist of two distinct processes:
1. Linear extension (upward growth)
2. Densification (lateral thickening)
The two processes can be largely independent of each other
e.g. in suboptimal conditions, a coral can maintain high growth rates (linear extension), but at the expense of skeletal density.
44
Calcification and growth rates are inherently variable
Branching corals grow up to 10 x faster than massive corals.
Male corals grow up to 40% faster than female corals.
Strong within species variability in growth rates.
this variability can be heritable
45
External drivers of calcification rates.
Zooxanthellae, sedimentation, irradiance, temperature, salinity, Turbidity, nutrients, Aragonite saturation.
46
Summary for lecture 6 calcification
* Planula larvae identify suitable settlement spots via sensory cues
* Competition is an important process determining community composition
* Coral growth – calcification +linear extension + budding
* Growth rates are highly variable:
Between growth forms
Between locations and across time
Dirven by many internal and external factors
47
what actually is calcification in coral reefs
Coral calcification is the rate at which reef-building corals lay down their calcium carbonate skeleton. It is a measure of coral growth, which is important for healthy reef ecosystems.
48
the 2 types Asexual reproduction and sexual reproduction in corals
Asexual: Budding and fragmentation.
Sexual: Brooding and broadcast spawning
49
Asexual: Budding
Division of polyps to form new ones.
Reproduction of individual polyps rather than colonies.
Modular Growth: successive addition of identical modular units to an existing organisms through budding.
50
Asexual: fragmentation
Piece of colony breaks off and develops into new colony:
Common especially in branching corals
Causes: e.g. storms, human disturbance
Mechanism used in coral restoration.
51
Asexual reproduction vs Sexual reproduction
What is Asexual Reproduction? Asexual reproduction is a mode of reproduction in which a new offspring is produced by a single parent. The new individuals produced are genetically and physically identical to each other, i.e., they are the clones of their parents.
Sexual reproduction: he production of new living organisms by combining genetic information from two individuals of different types (sexes). In most higher organisms, one sex (male) produces a small motile gamete which travels to fuse with a larger stationary gamete produced by the other (female).
52
Brooding
Only sperm are spawned
Taken in by female coral polyps containing egg cells
Internal fertilisation: embryo develops inside the coral polyp into a larva.
Planula larva released through mouth of the female coral at advanced stage of development.
53
Broadcast spawning
Predominant reproductive mode around 75% of all corals
Release of eggs and/or sperm OR buoyant gamete bundles (Containing eggs + sperm)
External fertilisation: eggs fertilised in the water column
Planula larva develops in the water.
54
Mass spawning
Synchronised, multispecies spawning over successive nights.
Triggered by environmental factors:
Seasonal change in water temperature and Lunar phase.
Increases chances of fertilization
Reduces Predation-related mortality.
55
Brooding Vs. broadcast spawning
Brooding:
-Fewer, but better developed larvae
-higher chance of survival
-generally shorter larval durations
-Lower dispersal distances
-reproduction throughout much of the year
-Less common (25%)
Broadcast:
-greater number of released gametes
-lower chance of survival
-longer larval duration
-potential for long distances dispersal
-need to synchronise reproduction, only once per year
-more common (75%)
56
Coral reproduction: It's complication..
Higher variation of reproductive modes between and within species
and even within individuals
A single colony can reproduce asexually and/ or sexually
A single polyp can reproduce via spawning and/or brooding
Corals can be hermaphroditic (having both male and female reproductive cells), others are gonochoric (distinct sexes)
57
Coral reproduction: It's complication..
Higher variation of reproductive modes between and within species
and even within individuals
A single colony can reproduce asexually and/ or sexually
A single polyp can reproduce via spawning and/or brooding
Corals can be hermaphroditic (having both male and female reproductive cells), others are gonochoric (distinct sexes)
58
Summary for Coral reproduction lecture
Corals have different modes of reproduction.
Asexual: budding and fragmentation
Sexual: brooding and spawning
Brooding and spawning are also prevalent in coral reef fishes
Mass spawning events important for both corals and certain fish species
the majority of marine organisms have a two-phased life cycle involving a pelagic larval stage.
59
Terrestrial systems: three stages of dispersal
1. Emmigration
2. Transience
3. Immigration
Active process involving a choice to stay or go and if so, how far?
60
Benefits of dispersal in living organisms
Gene flow
Local adaptation
Species distribution
Population dynamics
Species/population persistence
Conservation management
61
Metapopulation theory
Metapopulation: population of fragmented sub-populations occupying spatially separate habitat patches; interconnected by dispersal
Population connectivity: exchange of individuals among sub-populations; through larval dispersal
62
Why is the metapopulation theory important
Each sub-population may be subject to random extinction (e.g. coral bleaching)
Persistence of some local populations (sinks) depends on migration from other populations (sources) - rescue effects
Dispersal and connectivity assure long-term viability of the metapopulation as a whole.
63
Larval navigation
Orientation using sensory cues
Sounds: coral reefs produce a unique sound scape created by its inhabitants (e.g. snapping shrimps)
Odour: similarly, reefs produce a distinct olfactory signal
Sun azimuth: Some evidence that larvae can orient using a sun compass.
64
Summary for larval dispersal
Larval dispersal is the main means of population connectivity in marine systems
Connectivity has important ecological and evolutionary consequences.
It determines population dynamics, gene flow, range shifts and population's resilience to natural and anthropogenic disturbance
Larval dispersal is a bio-physical process, driven by a dynamic interplay between larval biology, seascape features and ocean currents.
65
What are algae?
Not readily defined…
Diverse collection of photo-autotrophic eukaryotes; (but also includes prokaryotes – Cyanobacteria
Not necessarily related organisms that come in a wide range of forms and sizes (from 1µm to 60m)
>70,000 describes species; most are aquatic
Differ from plants by lack of tissue differentiation
i.e., they lack true roots, stems and leaves
66
How seagrass is different to algae
Algae = Protists
No real differentiation
Nutrient uptake and transport via diffusion.
---------
Seagrass = flowering plants
True differentiation into a vascular system
Uptake via real roots and internal transport system.
67
What are the importance of algae.
Algae contribute about 50% of the global primary productivity
Represent a major sink for atmCO2 (mostly phytoplankton)
They are essential components of marine ecosystems
by forming the bases of almost all food chains
68
What is phytoplankton growth driven by?
temperature
irradiance
inorganic nutrients
pH
upwelling
69
Different types of phytoplankton
Diatoms:
Cell wall made of silica
-Deposits form
diatomous earth
Dinoflagellates:
Can form red tides
(harmful algal blooms)
-Zooxanthellae are dinoflagellates
Coccoliths:
Calcium carbonate scales
-Deposits form the White Cliffs of Dover
Cyanobacteria:
Ubiquitous in all ecosystems
-Can form blooms
Phytoplankton blooms:
Occur naturally, but increase through global change
-Can be toxic and/or lead to anoxic conditions
70
Turf algae
Only losely defined
More or less homogenous aggregation of short algae creating a turf mat
Can contain different species
Rapidly colonise dead coral
Important food source for herbivores
71
Major Groups of marine invertebrates
Porifera
Cnidaria
Echinodermata
Mollusca
Annelida
Arthropoda
72
Porifera – Sponges (5000-10 000 species)
Lack true tissue and body symmetry
No nervous, digestive or circulatory system
Large variety of sizes, shapes and colours
Often have intricate spikules as defense
Boring sponges are bioeroders of corals
Filter large amounts of water while feeding on bacteria, detritus and coral mucus
73
Cnidaria (>10 000 species)
Possess stinging cells (nematocysts) for prey capture and defense
Body form: radial symmetry
Two basic body forms:
Polyp (anemone like)
Medusa (jellyfish like)
74
Annelida: class Plychaeta (~10 000 species)
Annelids are segmented worms
Main class on coral reefs: Polichaeta
Each segment bears parapodia used for movement and respiration
Many are suspension feeders, but can also be predatory
Many burrow, build tubes and/or
drill into coral, some are free living
75
Echinodermata (~7000 species)
5-point radial symmetry (as adults)
Mesodermal skeleton composed of calcareous plates (called ossicles)
Water vascular system: hydraulic system used for respiration and locomotion
Composed of canals connecting numerous tube feet
Remarkable regenerative powers; some can form a new animal from a sparated limb
76
Mollusca (~85 000 species)
Largest marine phylum
(23% of all described organisms)
Specific features:
mantle - dorsal body wall
calcareous shell
radula - rasping tongue (not in bivalves)
single muscular foot
Vast variety of shapes, sizes and behaviours
Some classes:
Gastropods such as snails.
Bivalves such as clams
Cephalopods such as squid
77
Crustacea (67 000 species)
Large and diverse sub-phylum of the Arthropoda (includes insects and spiders)
Specific features:
Protected by hard exoskeleton
Moulting: shedding of the exoskeleton during growth
Segmented body
Biramous (two-parted) limbs
Nauplius larvae (the first larval stage of many crustaceans, having an unsegmented body and a single eye.)
78
Algae and invertebrates lecture summary
Both algae and invertebrates show extremely high diversity
-taxonomy
-shapes
-sizes
-ecological niches
Very little is known about this diversity
-lacking taxonomic expertise
-cryptic nature of organisms (small, camouflaged, hidden)
Many species/classes have vital
ecosystem functions (e.g. Sponge loop)
79
Why is the Coral Triangle so diverse? (1/2)
Centre of origin: CT is the cradle of biodiversity, gradients driven by dispersal from CT
Centre of overlap: high biodiversity as a consequence of range overlap of species between different biogeographic regions
Centre of survival: CT provides refuge from higher extinction rates in peripheral areas
80
Diversity and distribution of coral fish
Between 6000-8000 species
Diversity is not evenly spread
across the tropics
Highest diversity in the Indo-Australian Archipelago (aka Coral Triangle)
Similar patters also in:
Corals
Mangroves
Seagrasses
etc.
81
Why is the Coral Triangle so diverse? (2/2)
Alternative hypothesis:
High diversity is best explained by available shallow-water habitat (Bellwood & Hughes 2001; Science)
Overall, high diversity in CT still a
topic of debate and active research
82
Diversity in movement
Species differ markedly in their scale of (adult) movement
Most reef fish species don’t move much (<10km home range)
Some species are highly territorial
83
Sex change in fish
Many fish species can switch their gender
Sequential hermaphrodites:
permanent sex change at one point in life
Protogynous: Female to Male
Protandrous: Male to Female
Serial hermaphrodites:
repeated bidirectional sex changes
Driven by changes in gene expression, enzyme activity, and hormones
83
Sex change in fish
Many fish species can switch their gender
Sequential hermaphrodites:
permanent sex change at one point in life
Protogynous: Female to Male
Protandrous: Male to Female
Serial hermaphrodites:
repeated bidirectional sex changes
Driven by changes in gene expression, enzyme activity, and hormones
84
Summary for marine fishes
Highly diverse group
Many species highly specialised
Many groups perform vital ecological functions on the reef
Many species are directly or indirectly
threatened by human actions
(e.g. overfishing, aquarium collections, pollution, coral bleaching…)
85
What is community ecology?
Community: group or association of populations of two or more different species occupying the same geographical area at the same time.
Community ecology: the study of the interactions between species in communities and with their physical environment.
Who eats who?
Which species are most important for the ecosystem?
What factors govern biodiversity?
86
Coral reef biodiversity
Coral reefs are among the most diverse ecosystems on the planet (rainforests of the sea)
Around 70 000 named species → ~32% of all named marine species
(Fisher et al. 2015)
32 of the 34 known animal phyla (only 9 in tropical rainforests)
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What is biodiversity?
Basic definition: The variety of life on earth.
(including animals, plants, fungi, microorganisms)
Four general types of biodiversity:
Species: the variation of species in a given region/ecosystem
Genetic: variability of genotypes within species + genetic relatedness between species
Ecosystem: variety of ecosystems in a given area
Functional: variety of organisms performing different ecological functions
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What is the basic unit of biological classification
Kingdom
Phylum
Class
Order
Family
Genus
SPecies
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Between-species similarity 1 cryptic species
Cryptic species 1:
Different species can resemble each other morphologically
Example:
The gobiid genus Trimma
Originally: 52 species identified based on morphology
Now: 94 species based
genetics
Cryptic lineages
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Between-species similarity 2
Mimicry and camoflauge
Mimicry: evolved resemblance between two species (one mimics the other
Example 1:
Saddle fish resembles a pufferfish to deter predators
Example 2:
Blenny resembles a cleaner fish to get access to food (blenny feeds on fish tissue)
Many species are just not visible, because they:
are well-camouflaged
live hidden within the reef matrix
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Why are coral reefs so diverse?
Physical drivers of diversity
-Very high habitat complexity
offers abundance of microhabitats
Tropical climate:
ample sunlight + high temperatures
Biological drivers of diversity
Efficient internal nutrient cycling
(e.g. Sponge loop)
High degree of niche differentiation
to avoid competition for resources
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What is the sponge loop?
The sponge loop hypothesis proposes that sponges on coral reefs absorb the large quantities of dissolved organic carbon (molecules such as carbohydrates) that are released by seaweeds and corals and return it to the reef as particles in the form of living and dead cells, or other cellular debris.
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Ecological niches and what they include
Ecological niche: description of the ecological space occupied by a species.
Incorporates both the:
biotic and abiotic requirements of a species to survive, and
the role or function of a species in the ecosystem
Includes:
habitat (e.g. benthic vs. pelagic)
diet (e.g. corallivore vs. omnivore)
life history (e.g. spawning vs. brooding)
behaviour (e.g. day- or night-active)
geographic range
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Niche segregation
Competitive exclusion principle: two species with exactly the same resource needs cannot share the same niche at the same time
To avoid competition, species segregate their niches
Ways to do this, e.g.:
eat (slightly) different food
occupy a different habitat
be active at different times
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Trophic dynamics
Typical biomass pyramid
(observed in most ecosystems)
Only a fraction of the biomass is passed on to the next trophic level
→ less available energy higher up the pyramid
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Inverted pyramid
(observed in some aquatic systems)
Lower trophic levels have a much higher turn-over rate than higher trophic levels (faster reproduction, shorter lives)
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Coral reef food web
Organisms on the reef interact with each other in complex food webs
Trophic guild: a group of species in the community that utilises the same resources in a similar way
Predation: the killing by one living organism of another for food
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Functional diversity definitions
Ecological niche:
the ecological role an organism plays in the ecosystem
Functional ecology:
seeks causal links between
phenotype (morphology, physiology, behaviour) and the ecological role/function
Functional group:
a species or group of species that perform a particular function on the reef
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Key functional groups: cryptobenthic fishes
Cryptobenthics: small, inconspicuous fishes mainly of the families Gobiidae and Blenniidae
Cryptobenthics major food source for larger piscivores
Similar relative abundance, but much lower biomass
very high turn-over rate (faster development + shorter lifespan)
disproportionate larval supply (benthic brooders)
high productivity of crypto- benthics maintains energy flow
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high productivity of crypto- benthics maintains energy flow
Herbivores maintain the balance between algal and coral growth
Niche differentiation leads to different functional roles
Scrapers/small excavators: scrape algae off surfaces thereby clearing space for coral recruitment
Grazers/detritivores: graze on algal turf thereby also removing sediments
Browsers: feed on macroalgae
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Functional redundancy
The functional structure of an assemblage is a key indicator of an ecosystem’s resilience to disturbance
Functional redundancy: loss of one species is potentially compensated for by the actions of another
Even diverse systems may suffer from a lack of redundancy in some critical functions
~40% of ecological functions are performed by only one species
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Basic overview of morphology of seagrass
Adaptions to carry out photosynthesis
Adaptations wave action:
-Strap like leaves –anatomical reinforcement to resist wave action
-Roots
Lacunar systems: transport of oxygen
Reproduction and hydrophilous dispersal
High light requirement –average of 10% of surface
Distribution of seagrasses is primarily limited by the amount of light.
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Distribution of seagrass
Tropics to temperate zones
Found from low tide (spring) to depths of 50-60m, most abundant in immediate sublittoral
Most extensive on soft substrate
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Asexual Growth and reproduction in seagrass
Producer runners (Stolons) - increase size of meadow - limited dispersion.
Runners originally attached but make break-away from parent.
Example of vertical growth – Syringodium filiforme 17 cm y-1
Example of horizontal growth - 1.2 - 574 cm y-1 - new shoot every 1.1 - 7.5 cm of rhizome produced.
Interspecific variation = differing competitive abilities.
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Sexual reproduction in seagrass
Pollen and seeds are carried by currents (maybe faeces).
Majority of species of seagrasses have male and female flowers,
Others have both within the same flower. Male pollen fertilizes the female ovary of the flower, new genetically unique seagrass shoots are produced.
Flowers or their fruits can break off and travel long distances through the water.
Majority dioecious: separate male and female flowers
Disturbance and stress enhance seagrass flowering (stable beds favour vegetative growth)
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Epiphytic structure
Epiphytic organisms
Living on hard substratum offered by leaves
e.g. hydroids, microalgae (diatoms), cyanobacteria
e.g. Amphibolis - 100 different epiphytes (Ducker et al, 1977)
May cover > 90 % of leaf = reduced seagrass productivity
Light is attenuate by atmospheric and marine factors.
Further attenuated by epiphytes such as bacteria and algae and sponges growing on leaf surfaces.
Epiphyte growth induced by nutrient enrichment has led to loss of seagrass meadows through light deprivation.
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Seagrass fish habits
Fish in Seagrasses classified into four categories:
1. Permanent residents
2. Temporary residents (part of life cycle – Ontogenic shifts)
3. Regular visitors (diurnal or tidal visitors)
4. Occasional visitors (random feeding events)
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Summary of seagrass lecture
Seagrass distribution is pan global.
Diversity patterns follow patterns of coral reefs.
Seagrasses are productive as they can tap into nutrient-rich waters, but generally live in high light.
They are biodiverse since they offer firm substrate through the leaves, but they live in soft sediment with deposit feeders.
They are physiologically adapted to live in the sea, but their evolutionary origin is from the land.
They use current dispersal and animal dispersal, sexual and asexual reproduction.
Small organisms attached to the leaves – epiphytes.
Can be an environmental indicator.
There are fish that have ontogenetic shifts, diurnal and tidal shifts.
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What is a trophic guild
Trophic guilds are aggregations of species with similar diet compositions and may provide valuable guidance in the development of functional groups for use in ecosystem and network models (Yodzis and Winemiller, 1999).
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Introduction to mangroves
Mangroves line approx. 75% of tropical coasts, and are an important tropical ecosystem; being both a forest but also a marine component, affecting other coastal ecosystems.
Representatives from 20 families
27 genera of which 17 are exclusively mangrove
A total of 69 spp
But - debate about what are ‘true mangrove spp’.
Distribution:
Throughout tropical and subtropics
Low energy sites (estuaries) - limited by grounding of seeds and root formation
May penetrate upstream e.g. 300 km Fly River - New Guinea
Not dominant in Freshwater - outcompeted - saline = intermediate disturbance
Diversity varies geographically - greatest = Indo-Pacific
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Physical properties of mangroves
Fine sediments - low water and O2 exchange, high organic loading - high Bacterial respiration = anoxic sediments.
Positive feedback - root systems = deposition = accretion / deposition - further development e.g. Indonesia = 100 m.y-1
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Root systems of common mangroves
Stilt root of Rhizophora sp.,
Prop root of Rhizophora sp.,
Stilt root of Rhizophora
Planks root of Xylocarpus,
Knee roots of Bruguiera sp.,
Above ground root of Lumnitzera sp.,
Above ground root of Xylocarpus moluccensis,
Pneumatophores of Sonneratia,
Pneumatophores of Avicennia
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Adaptations to a variable environment in mangroves
The mangrove environment is a harsh one which is reflected in the relatively low diversity of the environment:
Highly saline, anoxic substrates
Wave action
Variable inundation and water availability
Salinity (variable from fresh, through brackish, seawater and even hypersaline)
Substratum unstable – subject to wind damage
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Common mangrove characteristics
1. Spreading lateral roots: prop roots, buttresses & stilt roots
2. Knee roots and pneumatophores to increase oxygen supply.
3. Lenticels –. O2consumed during immersion drops concentration inside to < 10%, but CO2 dissolves into seawater, so a lower internal pressure, as the tide changes, air is sucked in to supply
4. Leaves have thick waxy cuticle to avoid water loss– may also have hairs, and may hang down in high radiation
5. Expanded hypodermal layer under epidermis to store water
6. Large seed reserves – for seedling establishment, float = dispersal
7. Viviparous – e.g. Rhizophora, Avicennia, Ceriops. Precocious and continuous growth of offspring while still attached
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Specific examples of adaptations in mangroves
Mangroves like all halophytes have 3 possible strategies for dealing with the salt
Salt excluders: only in mild or intermediate stress.
Salt excretors: salt glands to excrete surplus salt active moving large amounts of salt against the osmotic gradient – requires energy. Saline droplets and salt crystals then accumulate on outside of leaves.
Salt tolerators: storage in bark, old leaves (then shed), or in succulent cells where they can dilute the salt intracellularly
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The nutrient cycle of mangrove litter
Crabs graze directly on litter
Fungi and bacteria break down litter
Prawns and fish feed on decomposed litter
particulate organic matter (POM) is a direct source of food
Remaining POM is taken up through mangrove root system
Up to 80% of mangrove litter is recycled below each tree
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How coral reefs and mangroves support each other
They can protect each other by reducing wave action.
They also provide shelter for juvenile fish
They both act as areas where different species of fish can go back and forth for ontogenic movement e.g. a snapper moving from the reef to mangroves
There is also foraging movements between mangroves and reefs. Such as the snapper so it can go to both places to eat smaller younger fish.
Coral reefs near mangroves have a different fish community with a higher biomass
E.g. large herbivorous fish (Scarus guacamaia) locally extinct when mangroves removed.
When protecting coral reef, nearby mangrove systems need to be considered.
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How much more carbon can mangroves sequester compared to rainforests.
Studies indicate that, weight for weight mangroves can sequester four times more carbon than rainforests
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What are the three different types of impacts?
Additive: The combined impact is the sum of both impacts by themselves 1 + 1 = 2.
Synergistic: The combined impact is greater than the sum of each impact by itself, 1 + 1 = anything >2.
Antagonistic: The combined impact is lower than the expected additive effect, 1 + 1 = anything from 0-1.9
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Sedimentation and reduced water quality.
Coral reefs naturally thrive in clear, oligotrophic (containing low levels of nutrients) waters with high solar irradiance.
High levels of anthropogenic runoff essentially create the opposite environment with algae dominating the area instead of corals.
causes of runoff can come from Deforestation + agriculture + urbanization + mining. which could also lead to higher levels of sedimentation.
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Why is sedimentation negative for corals.
Worldwide, coastal coral reefs are threatened by eutrophication and sedimentation from terrestrial runoff. Sedimentation events after terrestrial runoff or wave resuspension expose corals to fine nutrient-rich sediment that, when settled on reef-building corals, can bleach or kill exposed tissues.
Sedimentation has been identified as a primary stressor for the existence and recovery of coral species and their habitats. Sediment deposited onto reefs can smother corals and interfere with their ability to feed, grow, and reproduce.
Due to this it will also Greatly effect juvenile survival which would in turn reduce recruit survival.
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Mangrove accretion
Accretion: growth or increase by the gradual accumulation of additional layers or matter.
To persist, mangrove ecosystems must adjust to rising sea level by building vertically or become submerged. Mangroves may directly or indirectly influence soil accretion processes through the production and accumulation of organic matter, as well as the trapping and retention of mineral sediment.
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Impacts on growth and survival of sedimentation in corals
Sedimentation will:
Reduce calcification rates
Tissue thickness
Zooxanthellae density
photosynthesis
Adult colony survival
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Sedimentation impacts on fishes: overview
Its increases larval development time.
It decreases settlement success
Decrease foraging performance
Has varying effects on predator-prey interaction.
Overall condition of the animal decreases.
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More Harmful effects of run off regarding Phase Shifts
Increasing nutrient input to coastal systems (mostly N and P)
Leads to Eutrophication (overload of water bodies with nutrients).
This then causes excess algal growth with then can cause a phase shift rom coral to algal dominance.
These impacts can be elevated by other factors (e.g. overfishing, sedimentation)
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What is Ocean turbidity?
Ocean turbidity is a measure of the amount of cloudiness or haziness in sea water caused by individual particles that are too small to be seen without magnification. Highly turbid ocean waters are those with many scattering particulates in them.
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Light pollution in corals.
Artificial Light Pollution at Night (ALAN)
22% of the worlds coastline affected by artificial light.
Sources:
-Urban areas
-Fishing vessels
-Oil drilling platforms
Can disrupt natural biological cycles, e.g.:
-Circadian rhythms
-Diel vertical migrations
-Spawning times
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Coral exposed to ALAN exhibit altered patterns of gene expression
ALAN overrides endogenous biological clock
ALAN can reduce coral settlement success by 30%
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Noise pollution in reefs
Anthropogenic noise pollution can cause many effects:
Can induce stress, disrupt communication and orientation which leads to reduces fitness.
Noise will cause stress to the animals and cause an elevated heart rate.
This leads to reduces reaction time which decreases escape capacity in juveniles due to the noise pollution interfering with the sound of the reef which fish use to direct themselves.
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What is overfishing? (definition)
Removal of organisms from the ocean at a rate that exceeds the natural rate of replacement
One third of global fish stocks are overexploited
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what are the negative effects of cyanide and dynamite fishing (destructive fishing)?
Cyanide fishing stuns the fish and allows people to capture the fish alive so they can sell them for more profit. However, the cyanide will have adverse effects on the near by environment.
Dynamite fishing is where people use a sort of bomb to destroy the fishes' swim bladder. The sound can travel kilometres under water causing effects on the reef environment.
Both methods are illegal in most countries, but still widespread.
Unfortunately, this is done by bad people and get a lot of money from the fish they sell. However, they amount of damage they cause to the reef is greater than the total of their catch.
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Why are lion fish a good example of an invasive species/
They get into the Caribbean by people either putting them there illegally or they get carried over by storms.
They are very problematic because they have no predators and are dangerous due to their venomous barbs. They also lie in wait for food and eat the young of other fish. So they are a pest of the water.
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What is functional redundancy?
The concept of functional redundancy implies that species loss is compensated by other species contributing similarly to functioning. Functional redundancy can be revealed by the relationship between biodiversity and ecosystem functioning (e.g., biomass growth).
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How does El Nino effect coral bleaching?
This causes reefs to erode, destroying fish habitat and exposing previously protected shorelines to the destructive force of ocean waves. Warmer ocean temperatures caused by El Niño and global warming can lead to coral bleaching. The first widespread mass bleaching occurred during the 1982-83 El Niño.
An El Niño condition occurs when surface water in the equatorial Pacific becomes warmer than average and east winds blow weaker than normal. The opposite condition is called La Niña. During this phase of ENSO, the water is cooler than normal and the east winds are stronger. El Niños typically occur every 3 to 5 years.
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General coral dispersal fact.
There are a lot more corals in the pacific compared to the Caribbean.
around 800 species vs 60.
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How is black band disease caused?
Any point of impact such as a fish fin striking the coral will damage the protective cell wall. This then allows micro-organisms to invade the coral. As the organisms grow they take up the oxygen in the coral causing the black anoxia ring.
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Stoney Coral Tissue Loss Disease (SCTLD)
SCTLD, affecting over 20 species of hard corals in the Caribbean since 2001
It is currently causing significant damage to coral reefs in Florida and beginning to be reported in other Caribbean islands.
SCTLD poses a particularly significant threat to Caribbean reefs because of its large geographic range, extended duration, high rates of mortality, and large number of coral species affected.
SCTLD is suspected to be caused by bacterial pathogens and can be transmitted to other corals through direct contact and water circulation.
Many current efforts are under way to identify disease agents, relationships with environmental factors, strategies to treat diseased colonies, and identify genotypes of corals that are resistant.
Doesn't effect Acropora which is the most abundant species. So you have SCTLD effecting rarer corals with black band disease effecting acropora.
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Corallivore activity on reefs.
Any animal that eats corals!
Fish Examples:
-Chaetodontidae (butterfly fish)
-Scaridae (parrot fish)
Invertebrate Examples:
-Acanthaster planci (Crown of thorns)
-Drupella
Corallivore activity causes direct tissue loss, also increases potential for infections e.g. ciliates
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Case Study: Acanthaster planci (COTSF)
Crown of thorns star fish are a huge problems because they have risen in number and cause great damage to reefs by turning their stomach inside out and digestive the coral.
Main way of managing them is by getting people to catch them. However, it is very labour intensive.
Females produce up to 60 million eggs each year.
Are capable of reproducing within 2 years.
they have high juvenile mortality
eat a variety of different prey.
Live in a wide range of environments.
Run-off will cause algal blooms which COTSF thrive in which would put coral reefs at an even higher risk.
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What is the natural causes hypothesis?
Pre-Settlement and natural.
The Gaia hypothesis, named after the ancient Greek goddess of Earth, posits that Earth and its biological systems behave as a huge single entity. This entity has closely controlled self-regulatory negative feedback loops that keep the conditions on the planet within boundaries that are favourable to life.
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planktotrophic vs lecithotrophic
Planktotrophy in this species involves production of many small ova that develop into feeding larvae with a two- to three-week planktonic period. Lecithotrophy involves production of fewer, larger ova that develop into nonfeeding larvae that are brooded longer and have a brief planktonic stage.
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What effects could rising carbon have on the sea.
Increase in atmospheric carbon:
it could lead to: increased sea surface temperature, storm activity such as category 4-5 hurricanes becoming more common, sea level rise leading to coral reefs drowning, environmental anomalies such as marine heatwaves. and finally ocean acidification which leads to aragonite saturation.
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Why is Ocean acidification bad. including aragonite saturation.
It leads to an increase in ocean pH (around 7.8 -8.2) However, this doesn't do that much.
However, the increase in Hydrogen ions will discount the carbonate ions leading to the corals not being able to build their skeleton. This then leads to aragonite saturation.
Aragonite saturation state is commonly used to track ocean acidification because it is a measure of carbonate ion concentration. When aragonite saturation state falls below 3, these organisms become stressed, and when saturation state is less than 1, shells and other aragonite structures begin to dissolve.
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Why are increased temperatures bad for coral?
Rising (or even falling) water temperatures can stress coral polyps, causing them to lose algae (or zooxanthellae) that live in the polyps' tissues. This results in “coral bleaching,” so called because the algae give coral their colour and when the algae “jump ship,” the coral turns completely white.
Also coral are adapted to live at the highest temp they can. However, a slight increase to the bassline will cause great stress on the coral.
Higher temps will melt ice, which will increase sea level and will make corals sink. This is bad for Caribbean corals because they grow a lot slower and smaller.
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Affects that storms can have on coral reefs.
Storms cause damage to reefs which will produce rubble in the sea. Coral is then not able to settle on this new rubble in the future.
However, there is an antagonistic impact where storms can cool the ocean after a heat level increase.
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What is Calicoblastic epithelium?
v
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Sea level rise: Associated with rise in atmospheric temp
Thermal expansion
Glacier melting
Terrestrial storage
Thawing of permafrost
Deposition of additional; sediment.
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Aragonite saturation
Carbonate mineral, crystal form calcium carbonate, CaCO3
Naturally formed in mollusc shells/coral skeleton
Indicator of calcification potential
Reduced aragonite -> reduced calcification -> reduced coral growth -> ???
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What exactly is coral bleaching
When corals bleach they commonly lose 60-90% of their zooxanthellae and each zooxanthellae may lose 50-80% of its photosynthetic pigments (Glynn 1996).
Bleaching, or the paling of zooxanthellate invertebrates, occurs when the densities of zooxanthellae decline and / or the concentration of photosynthetic pigments within the zooxanthellae fall (Kleppel et al.1989).
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How does coral bleaching Occur?
Loss by the coral animal of some or all of its symbiotic algae due to external stressors
-> White calcium carbonate skeleton becomes visible
- Short-term stress: possible for coral to recover
-Long-term stress: coral likely to die because of energy deficit
-Overgrowth by algae
---------------------------------
Can be triggered by range of different stressors:
Low salinity, Runoff and pollution, Air exposure during extreme low tides, High solar irradiance, high temperature.
Stress can alter algal photosynthetic activity
- production of excess reactive oxygen species (ROS) -> oxidative stress
- Expulsion of algal cells by coral host.
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Is the frequency and severity of coral bleaching increasing??
YES
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How can we increase coral survival?
Corals may be able to acclimate and/or adapt to climate change to some degree
Reciprocal transplant experiments: corals can shift their thermal tolerance
Corals from variable or naturally hot regions have higher capacity to adapt.
Colonies can also partner with more tolerant symbionts after bleaching.
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How does coral bleaching effect fishes?
Many reef fish depend on structural complexity provided by live coral.
Shelter, food, settlement habitat.
Coral bleaching leads to a reduction in structural complexity (dead corals degrade over time)
Impact more severe for habitat specialists.
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Effects of habitat degradation on settlement
Coral reefs emit characteristic biophysical sound signal.
Fish larvae can use reef sound as settlement cue.
Reef degradation alters the soundscape
Negative feedback loop may hamper recovery.
Meaning less larvae will be attracted leading to further degradation.
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Effects on habitat degradation on post-settlement selection
Settlement in bleached and/or dead coral reduces survival in juvenile damsel fish
Settlers exhibit differential behaviour in degraded habitat
Stray further away rom shelter higher vulnerability to predation
Impacts on population viability and reef recovery ??
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Direct effects of rising temperature on fishes
Fishes are ectotherms and thus sensitive to changes in temperature
Temperature has positive effects on metabolism up to a certain point, but negative beyond that.
Increased ambient temperature -> reduced fertility.
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Drivers of variable responses in reefs
Coral Species variability
Coral holobiont variability
Coral population variability
Regional variability
Temporal variability
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What is an MPA ? (marine protected area) and different types.
Multiple Use: Allows extractive uses (like fishing) with some restrictions.
No-Take: MPAs that allow people to use the area but prohibit extraction or any destruction to the area. These are also called marine reserves.
No Impact: MPAs that allow people to use the area but extraction, disposal of possible pollutants, the installation of materials, and disruption to the environment of any kind is not permitted.
No Access: MPAs that restrict all access to the area. Also, very rare and may only be used for research purposes
IUCN (International Union for Conservation of Nature) defines a protected area as an: Area of land and/or sea especially dedicated to the protection and maintenance of biological diversity, and of natural and associated cultural resources, and managed through legal or other effective means.
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What are the 2 main factors that affect coral bleaching?
Thermal induced bleaching/paling
They could also pale because of too much light causing a degradation of pigments or zooxanthellae being dispelled -> coral tissue peeling off of the skeleton leading to an impossible recovery.
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Different types of coral susceptibility to coral bleaching/paling
Type 2 corals shows recovery, such as massive corals like Porites are usually type 2.
Type 1 corals do not show recovery, such as branching corals like Acropora, meaning they are more vulnerable.
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Active vs passive conservation
Active restoration is where management techniques such as planting seeds or seedlings are implemented, and passive restoration is when no action is taken except to cease environmental stressors such as agriculture or grazing.
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What is the ridge to reef idea?
The ridge to reef approach aims to provide a holistic intervention for protecting the coastal area by targeting environmental degradation in the uplands ("ridge") that impact coastal ecosystems through sedimentation, by restoring the shoreline and protecting marine ecosystems ("reef"), thereby mitigating storm surges, coastal and inland flooding and reduce people’s exposure and vulnerability to these hazards. At the same time, aiming to provide direct livelihood benefits to targeted households and stakeholders in the project. This includes run off as well from nearby land which can cause adverse effects.
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What is a spill-over effect in reefs?
Fish in the protected area will get too abundant and venture off outside the area/ fish may get too big and produce more larvae.
Abstract. The net movement of individuals from marine reserves (also known as no-take marine protected areas) to the remaining fishing grounds is known as spill-over and is frequently used to promote reserves to fishers on the grounds that it will benefit fisheries
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What are the 4 steps in coral reef recovery. (the 4 R's)
Restoration
Rehabilitation
Regeneration
Rewilding
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The definitions of the 4 R's
Rehabilitation: returning a systems ability to provide the ecosystem systems services it was once capable of providing
Restoration: returning a reef through active measures back to its original state or on a path to that state
Regeneration: Intervening to assist the recovery of an ecosystem that has been degraded, damaged or destroyed
Rewilding: restore (an area of land) to its natural uncultivated state (used especially with reference to the reintroduction of species of wild animal that have been driven out or exterminated).
Restoring a coral reef is done so that it is able to assist in the regeneration of the wider coastal ecosystems.
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Guiding principles of Ecological Restoration
Restoration is a critical tool for achieving biodiversity conservation, mitigating and adapting to climate change, enhancing ecosystem services, fostering sustainable socioeconomic development, and improving human health and well-being.
Requires the integration of knowledge and practice. Science and other forms of knowledge are essential for designing, implementing and monitoring restoration projects and programs.
An engaging and inclusive process enabling full and effective participation of indigenous, local and disenfranchised communities
Practiced locally with global implications.
Policy-relevant and essential.
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How does HOPE reef assist with coral conservation?
Reefs are destroyed from blast fishing which creates rubble which then stops corals from settling. MARRS have decided to coat these spider webbed frame that they can put sand on from the site that they are trying to preserve. This then allows lots of corals to attach to this frame rather than the rubble on the sea floor.
These web frames also give a place for juvenile fish to live which in turn makes the coral reefs more diverse and healthy which helps improve reef complexity.
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What is ocean stratification and how does it affect the marine environment?
Stratification is a term used to describe when two distinct layers occupy the vertical water column in the sea: the near-surface one is less dense than the near-bed one (see also Stratification / potential energy anomaly assessment).
For example, periods of increased ocean stratification have been associated with decreases in surface phytoplankton biomass. In coastal waters, prolonged periods of stratification can lead to hypoxia (low oxygen), causing mortality of fish, crabs, and other marine organisms.
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Precursors to Active Reef Restoration
Active restoration should be a last resort/ sledgehammer approach.
Reef restoration should not be used in isolation
Protective management and legal frameworks
You Need an understanding of the natural ecological system.
understand factors impacting the system.
Reducing these or eliminating these impacts – or adapting techniques to overcome impacts
Restoration requires multi-disciplinary approaches
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Coral Reef Restoration: where has it come from?
Exponential increase in the number of restoration projects
Huge variability in the scales on which they operate
Dealing with local and global issues
Need to be very clear on objectives
Major problems are cost and scalability (we should be doing a lot more restoration.
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Harvesting corals
Harvesting fragments from nearby donor reefs
-Surgical bone cutters, wire cutters or hammer
-Larger fragments > survival but can be detrimental to donor colonies.
-The 10% rule
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Corals of Opportunity
-Non-destructive method - fragments that are already detached’
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Coral Gardening
-Nurseries = Biomass Production Systems
-an “intermediate” nursery phase
-Land or Sea based
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Direct Out-planting
Most common method of coral restoration (used in ca 70%)
Bypasses the post-settlement demographic bottleneck of coral larvae,
Larval and early stage settlement = high mortality and slow growth
From Harvesting, COPS or Coral Gardens or land based aquaria
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Attachment of Corals
Corals must be firmly attached
Most common method uses epoxy
Also cable ties
Cement can be cast into disks ex-situ with the base of coral fragments encased in the cement, or attached with glue
New initiatives: the Coral Clip
Survival of corals between 60-70%
Methods differ in terms of time and labor costs
Techniques used depends on objectives; Scale, Resources: Environment
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Mars Assisted Reef Restoration System
Mars used supply chain thinking to debottleneck restoration and maximise efficiency of project diversity.
Also diversifies participation of local community groups.
They have now used sound levels to detect how well the restored reefs are getting on. and that after 3 years they sound almost identical to healthy reefs.
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Coral gardening
Field based nurseries tend to be more successful and less expensive than laboratory
Choose a site that is has right environmental setting
- exposure
-flow
-water quality
-ecology
-impacts and hazards
Use material of long durability underwater for your nursery
Fragments grown to a size that offers a high likelihood of survival
Maintenance for corallivores, pests and fouling organisms
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Floating or Mid-Water Nursery eg Rope Nurseries
Floating structures must be constructed in a manner that reduces the likelihood of entanglement with other marine life, such as sea turtles or marine mammals.
Keeping structures at least 1 meter above the seafloor reduces predation and sedimentation during periods of high wave energy.
If nurseries are built in an area where bleaching is a concern, nursery structures can be lowered during high temperatures to reduce the likelihood of bleaching. This same concept may be applicable for high energy conditions such as storms,
Increase coral growth and decrease the prevalence of disease and predation, depending on the location. However, faster coral growth may result in reduced coral skeleton density, resulting in fragile fragments that are prone to breakage.
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What is micro fragmentation?
Massive corals not used often in restoration - slow growth and morphology
A diamond blade saw used to cut small fragments (1 cm2) which are mounted on tiles.
Tiles kept in artificially lit and aerated aquaria for weeks,
Placed in outdoor flow-through aquaria.
> 12 months, fragments sub-divided to generate new micro-fragments or outplanted.
Micro-fragments in an array will readily fuse together to form a larger colony (i.e. ‘re-skinning’).
High survival and rapid growth of fragments
Re-skinned corals reach sexual maturity more rapidly (~18 months) than naturally growing corals (~10 years)
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Larval Propagation in coral reef conservation.
Out-planting sexually propagated corals is a recent technique aimed at increasing coral cover on degraded reefs, while preserving genetic variation within recipient populations. While this approach is increasingly successful, several challenges currently prevent its application on large scales.
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Different mangrove roots and their functions?
Stilt roots: As soon as stilt roots reach the ground the tip of the stilt root develops an underground root system with which it connects the stilt root into the ground and then develops one or more further stilt roots which grow arcuately into the air to again run into the ground to develop an underground root system, this process repeats several times.
Another important ability of stilt roots is to allow the exchange of gas in oxygen-poor sediments using lenticels on the roots.
Knee roots: Knee roots emerge as a root loop from the underground root system and allow the exchange of gases in oxygen-poor sediments. Each underground horizontally growing root develops several knee roots at regular intervals. Most knee roots have numerous lenticels with the ability to exchange gas.
Pneumatophores: are roots that grow vertically up from the underground root system. used for gas exchange at the surface.
Buttress roots: Buttress roots are developed by many trees, concerning mangroves especially Heritiera littoralis and Pelliciera rhizophorae are famous for their buttress roots.
Buttress roots provide huge trees stability, especially in tropical areas, and the buttress roots can grow up to 10 meters in height. Buttress roots, also called buttresses do not continue their growth underground as they do above, underground buttresses develop a huge amount of small roots that grow in the soil under the buttress root.
