Rob's lectures Flashcards
Distribution patters influenced by environmental gradients
1.Particle size (grain size gradient)
2.Salinity
3.Vertical (emersion, depth)
4.Wave exposure
5.Latitude + temperature
6.Anthropogenic disturbance
1 particle size
-Muddy shores (mangroves)- terrestrial plants, halophyte (salt tolerant), anoxic sediments (adaptation), sediment accretion, coastal erosion and protection. Infaunal communities. Serve as sponges for refuge for other species, they also buffer and absorb storms for us.
-Sandy beaches- physical substrate shifts and is unstable. Burrow to avoid stress and predation, substrate disturbance from waves, fauna rely on imported food. Low primary production.
-Stones + boulders- intermediate disturbance hypothesis, disturbed habitats can have more diversity than undisturbed/pristine habitats.
-Rocky shore- hard and stable substrate, organisms are visible. Live on top of substrate as epifauna and epifloral. Tend to be abundant and small, or sessile and sedentary.
2 salinity gradients
-catchment to coast. Fully marine = 35 psu/ppt. Can be fully stratified, moderately stratified (tide mixing or wind), vertically homogenous.
-estuaries- variable salinity regime with few true estuarine species (that complete the whole cycle. Many visitors; both anadromous, catadromous. Adaptations include Osmoconforming and osmoregulation.
-rivers- broader biogeographic impacts of freshwater input. Yangtze river plume has been going on for years and speciation is occurring now.
3 Vertical- shallow subtidal to intertidal terrestrial
Ecotones = abrupt changes in vegetation or two adjacent and homogenous community types, producing a narrow ecological zone between them. Zonation also within coral reefs (also in forests).
4 wave exposure gradients
Horizontal along shore line. If waves change the coastline, the coastline changes the biodiversity.
6 anthropogenic disturbance gradient
There is normally a functional homogenization. Artificialisation of coastline.
Upwelling
Driven by surface winds, either seasonal or constant. Normally drags water up from the bottom and pushes warm surface water down.
Aragonite
A crystal form of calcium carbonate, which is the primary mineral used by corals to build their skeleton. It’s more soluble than calcite so it dissolves more in acidic waters. It forms coral reefs; they extract calcium and carbonate from seawater to make the aragonite.
Aragonite saturation State (Ωₐ )
-Ωₐ > 3.3 → Favourable for coral growth.
-Ωₐ ~2.5 → Growth slows, dissolution increases.
-Ωₐ < 2.0 → Corals struggle to grow, reef erosion outpaces growth.
Natural acidification in Bahía Culebra
-Seasonal upwelling bring carbon dioxide rich waters and low pH waters
-Non-upwelling seasons still sees acidification events
-Daily or seasonal fluctuations are controlled by photosynthesis and offshore water input
Aragonite saturation (Ωₐ): upwelling vs none
-Non-upwelling: Ωₐ > 3.3
-Upwelling: Ωₐ < 2.5 (reduced calcification & increased dissolution).
Coral growth in low pH
Showed high coral extension rates despite natural acidification. When the conditions aren’t right their growth slows, but then when the conditions are right, they grow even faster. But reefs are really thin despite how they are spread out. This may be because there is high bio-erosion and dissolution, which prevents long-term reef accumulation since it’s hollowing out from the bottom.
Red tides
Pollution when there is a lot of shit in the sea. Normally with heavy rains and strong upwelling.
Succession
The non-seasonal, directional + continuous pattern of colonisation + extinction of species populations.
Primary succession
Succession in an area where no organisms are present. For example, if artificial pontoons are introduced and algae starts growing on it.
Secondary succession
Succession in an area where a biological community is partially intact. Like extreme wave exposure on a rocky shore.
Degradative succession
Succession on or in dead or dying organic matter.
1883 eruption of Krakatoa
70% of island was blown out, including jungle, animals, humans. It put so much ash in the atmosphere that the earth actually cooled. It was the first time Europeans started studying succession. However, nature came back over time.
The climax state: differing hypothesis
An emergent stable community in a successional series is called the climax state, which is self-perpetuating and in equilibrium with the physical and biotic environment.
-Monoclimax hypothesis = only one climax community toward which all communities are developing
-Polyclimax hypothesis = many climax communities may be recognised in an area
-Climax-pattern hypothesis = natural communities are adapted to the environmental factors.
Regime shifts
Or phase shifts
-When the ecosystem state shifts due to an environmental driver
-Also known as alternative stable states
Coral reefs
-Non-reef building is called ahermatypic, globally distributed
-Reef-building is called hermatypic, but are mainly restricted to the tropics. They live in colonies, skeletons deposit CaCO3, polyps have zooxanthellae, and do photosynthesis by day and feed with nematocysts by night.
Corals resource availability
coral have improved resource availability through the coral-polyp associations through obligate mutualism and trophic interactions. Zooxanthellae provide nutrition to the corals as photosynthate, and they get nitrogen as a coral waste product.
Coral landscapes of fear
-There are grazing halos which are made by the predator-prey interactions. Sharks push all of the grazers into limited patches around the reefs.
-Without predators there are no halos.
EU habitats directive definitions of a reef
Reefs can be either biogenic concretions or of geogenic origin. They are hard compact substrata on solid & soft bottoms, which arise from the sea floor in the sublittoral & littoral zone. Reefs may support a zonation of benthic communities of algae & animal species as well as concretions & corallogenic concretions.
Ecosystem services
Disturbed reefs become colonised by invasive oysters from nearby farms in France. Gaps between reefs are taken over by invasive slipper limpets, and surrounding sediment is home to bivalves and polychaetes.
How to help fish on degraded coral reef
-Acoustic enrichment can enhance fish community development on degraded coral reef habitats.
-He played the sound of a healthy coral reef to the degraded ones, which attracted fish enough to come back and colonise it
-By adding a sound landscape, more fish came in (particularly parrotfish) and reproduced as well.
Refuge from physical stress on saltmarsh ecosystems
-Habitat modification by plant and animal
-By reducing salinity there was a positive effect on sea grass, new interactions shifted it from positive to negative with marsh elevation.
r-selected species
r = pr capita rate of increase (expanding populations, faster LH (more allocation to reproduction))
short-lived, rapid development, many offspring, disturbed environments
k-selected species
k = carrying capacity of pop (stable populations, slower LH (more allocation to survival))
long-lived, slow development, few offspring, stable environment
Coral holobionts
Zooxanthellae,
viruses, bacteria.
Healthy holobionts = healthy reefs.
Coral ecosystem services
Worth between 6 - ten trillion dollars per year, without reefs, that whole industry and local livelihoods are done. There has been a 30% loss of coral cover from 2016-2017 alone.
Coral reef restoration
Increases coral abundance, carbon sink, but are no more tolerant than parent corals. There is a 65% success rate, and is estimated to cost 1.6 million dollars per hector.
Tolerance + how to measure it
-Use immune systems as a measure of stress
-The maintenance of homeostasis (being healthy) = immunity
coral immunity
They do have diseases or disorders, a response to this could be coral fluorescence. Corals can, for example, produce darker spots (melanin) around affected areas.
Levels of immunity parameters underpin bleaching and disease susceptibility of reef corals.
Melanin synthesis in vertebrate community
Role = to defend mechanisms in innate human response, and its triggered by the detection of pathogens or wounds. <enzyme phenoloxidase (PO) initiates melanin production. Prophenoloxidase (proPO) is activated by pathogen recognition, it converts tyrosine to dopa + dopaquinone. This leads to melanin polymerization.
Function = encapsulates parasites and pathogens, can form melanotic nodules, produce reactive oxygen species (ROS which have antimicrobial properties.
Regulated = by serine protease cascades to prevent overactivation. In arthropods, and molluscs too.
Coral bleaching
Different categories of bleaching.
Those that bleach the quickest are those least able to process phenoloxidase.
Fast growing corals get sick and die quickly, but if they survive, they also bounce back quickly.
Healing in corals
There is cell filtration. If you plug a hole (injury) in coral and don’t allow anything else in, it begins to heal, like humans. They struggle to heal in dirty, murky waters. Warmer water affects the immunity of tolerant reef coral. In warmer water they are unable to have an immune response, they are helpless.
Why are corals fluorescent?
Fluorescent proteins have antioxidant proteins, they all respond differently to different wave lengths. When corals have inflamed tissue, they have more fluorescent proteins. It’s a way for coral to build an immune system, but they also have to shut down the pathway for melanin, otherwise they could go into overdrive.
Damage threshold hypothesis
the immune activity vs the damage burden
coral immunity mechanisms
include melanin synthesis, antimicrobial peptides, and fluorescent proteins that contribute to disease resistance
Coral conservation
Long-term success depends on integrating immune resilience into conservation strategies.
We must prioritise immune monitoring and identifying tolerant coral species to enhance outcomes.
mangrove facts
Some of most productive ecosystems in the worlds, nearly 30% of commercial fish in the world depend on the mangrove in some stage of their lifecycle. Areas with more than 1km of mangrove can leave infrastructure unaffected by hurricanes, even category 3.
67% of historical mangrove habitat has been lost or degraded worldwide, 35% has been lost globally over the last two decades.
mangrove locations
Normally within 20 degrees isotherms, like corals (coral triangle). And are replaced by salt marshes at higher latitudes. Most mangroves are found in developing countries (Indonesia).
Main mangrove genera
Avicennia (black mangroves)- roots emerge from the ground in tubes, leaves are opposite and opaque green.
Rhizophora (red mangroves)- can be found in rainforests too, stilt-shaped roots that detach laterally from the trunk. There can also be hanging roots, leaves are opposite and arranged in groups.
family combretaceae
Also a type of mangrove, don’t have particular roots, distinguished by two glandular structures on the petiole.
Why do mangroves zonate?
Due to different abilities to deal with waterlogged sediment, salt levels or nutrient levels.
Waterlogging + solutions
Waterlogged sediment- normally anoxic, tree roots need oxygen, so they have special aerating devices.
Knee roots (in Bruguiera)- that periodically break at the surface and then submerge again to get oxygen.
Aerial roots (in Rhizophora)- which leave the tree up to 2m from the group, provide aeration through lenticles which are pores.
Pneumatophores (in Avicennia)- which are shallow roots which extend metres from the tree and have tubes that emerge from the water, also with lenticles.
salt uptake in mangroves
Disrupts cellular mechanisms + is fatal for most plants.
-Exclusion of salt by roots
-Tolerance of salt in tissue
-Secretion of excess salt via bark or they shed leaves
Mangrove reproduction
-Pollination (wind, bees, moths, butterflies)
-Propagule development and fecundity
-Dispersal and settlement
Propagules and fecundity
-Seeds need to tolerate inundation and high-salt levels
-Following pollination, the growing embryo remains on the parent plant for up to three months (vivipary)
-Leaves the parent plant as a fully developed seedling or propagule, can be up to 1m
-Represents 10-40% net primary production
Dispersal and settlement
-Rhizophora seedlings drop from parent plant into the water
-Initially they float horizontally, turning vertically after about a month when roots develop
-Roots drag on bottom and seedlings can get stranded horizontally or sink
-Seedlings erect themselves after rooting in the mud
-If not rooted within 30 days, they remain buoyant for more than a year
mangroves + corals
-Mangroves act as sediment traps to keep coral reef water clear, protecting them from runoff
-Act as a nursery ground for coral reef fish
Mumby et al. 2004: individual fish are larger on reefs near mangroves, biomass of reef fish was higher closer to mangroves.
