Solar Radiation and Heat Transfer

Radiation

Differential solar heating of low and high latitudes is what drives the large-scale atmospheric and oceanic circulations of the planet. Most solar energy reaches the Earth as short-wave radiation (insolation) that reaches the surface, although some is reflected back in to space according to the albedo effect; the remained is absorbed and warms the atmosphere above it. The atmosphere and surface radiate thermal (long-wave) radiation back in to space. 

This differential solar heating fostered an equator-to-pole gradient in atmospheric and surface ocean temperatures, and Stefan-Boltzmann's law states that every body above absolute 0 (-273C) radiates. Wein's law describes that all bodies at a high temperatures radiates short wavelengths, whilst colder bodies radiate longer wavelengths. The sun behaves virtually as a black body, absorbing all energy received, and radiating energy at the maximum possible rate for a given temperature. 

Atmospheric layering is a consequence of the absorption of incoming radiation by water vapour gasses in the atmosphere. The amount of heat absorbed will depend on the specific heat capacity of the surface; land has a lower heat capacity than water, therefore it heats and cools much faster. The oceans are a huge source of stored heat.

Mid-Latitude Disturbances

In the westerly belt there is a complex pattern of moving high and low pressure systems: between 6,000-20,000m there remains a distinct westerly flow. Jinman (1861) held that storms develop where opposing air currents form lines of confluence, which were later called fronts.

The Global Climate System

This is composed of the unstable and rapidly changing atmosphere; the sluggish ocean with a thermal inertia, important for moderating atmospheric variation; the snow and ice cover (a.k.a cryosphere); and land surface - biosphere and lithosphere. The most important interaction is between the dynamic atmosphere and regulating ocean, althought he living matter of the biosphere also plays a key role in the system. The biosphere influences incoming radiation, out-going re-radiation, and the atmospheric composition. Marine biota further play a fundamental role in dissolution and storage of carbon dioxide. 

The driving mechanism of global climate is named 'radiative forcing' and anthropogenic forcings has added a new dimension to this. Radiation imbalances have arisen from natural processes and anthropogenic activity. The systems of climate and weather display extreme sensitivity to their initial conditions, and a small change in a weather system may have a disproportionately large impact on the whole. This is known as the Butterfly Effect. 

Heat

Heat may be transferred via conduction, and water is far more efficient at this than air - conduction is the means of transfer by molecular agitation. 

Free convection is another method, and describes the free rise and movement of air parcels to form cumular-type clouds. 

Forced convection describes orogenic displacement, when the air is forced to rise, forming strata-form clouds. This is the movement of heat energy by mass movement. 

Advection describes the nearly-horizontal transport of heat by oceans and the atmosphere, such as that found in the Jet Stream. 

Sensible heat is that which is exchanged by a body or thermodynamic system that changes the temperature and some macroscopic variables of the body. Volume and pressure will not be affected.

Latent heat is that which is released in a changing material state; in the process of evaporation a vast amount of heat is required to turn water in to vapour, ergo it is stored as the latent heat of vapourisation. This energy is taken from the surface of the oceans. Latent heat transport is responsible for the transfer of large quantities of heat energy in the ocean atmosphere system. 

Temperature Variation

Insolation is the absorption of solar radiation by the ground, and the nature of the surface conditions, sucha s moisture content, affects this radiative process. The specific heat capacity for the land is larger than that for the ocean, which warms and cools much more slowly. Cooling the oceans by 0.1C releases enough heat to raise surface air temperature by 10C. Diurnal ranges across the earth are moderated by the oceans. Asia, for instance, warms madly in the summer months, while the converse occurs in the winter, as cold, dense and dry air masses frequently block others, affecting the temperature globally. 

The Tragedy of the Commons

Economist Mancur Olson argued that local governance develops a vested interest in maintaining local resources, whilst the sequential exploitation of roving bandits severs the local feedback and motivation to implement conservation practices. Berkes et al., 2006, examine the effect of roving bandits, and describe it as 'the tragedy of the commons.' This effect has been commonly recognised in the process of globalisation and the increased harvesting capabilities of fisheries.

The tragedy of the commons: A shared, open-pool resource is competitively depleted by harvesters who have no incentive to conserve; the dictating approach is that whatever one individual does not take another will, therefore there is no point in conserving the natural capital, so one may as well gain as much from the resource as one possibly can at the time. 

Commercial fishing was generally recognised as unsustainable after the process became industrialised and the diesel engine was introduced. The catchability coefficient of one given species is expressed as F = qf, where f describes fishing effort and q represents the effectiveness of a gear. The problem with this model is that q is subject to technologial fluctuations, and f cannot be effectively recorded. So there a gaping holes in fisheries science.

The idea of coral reef fisheries being sustainable is laughable: local fishers employ blasting methods and poisions such as cyanide, which actively devastates the habitats that support the communities they seek to fish - Cheilinus undulatus (humphead wrasse) has suffered serial depletion. How can a fishery, which destroys the habitats of the species upon which they rely, ever be considered sustainable?

Ecological Implications

Sequential exploitation of a marine resource or species that will often be a significant conduit for the flow of energy and materials within a community structure naturally poses great risk. One example is the historic exploitation of sea otters for their pelts in the Aleutian Islands (SE Bering Sea) - this key stone predator would control sea urchin populations, but their depletion caused mass deforestation of kelp beds by plagues of sea urchins for over a century. 

Of course, sea urchins themselves were also being harvested; in 1945 only around the east coast of Asia - by 1995 across the world. In Maine, this green sea urchin (Strongylocentrotus droebachiensis) population was rapidly depleted, after the trade-induced increase in demand occurred too rapidly for the local human governance to effectively respond with species conservation intent. 

Simplifying the food webs by rapidly depleting one element or species is the tragedy of the commons, and the resilience of the marine ecosystems towards global/natural threats such as climate change are significantly eroded. 

Management Implications

Often in the past, a local resource will have vanished before a problem is even noticed - further, serial depletions of local stocks may be masked by shifts in exploitation, i.e. changing where you fish, for instance. MPA's and NTAs currently existing are generally too small to sustain processes within the broader seascape - it must be remembered that protected zones are not closed systems. The Great Barrier Reef Marine Park is too small to sustain populations of marine mammals, turtles and migratory sharks.

Addressing the ecological impacts of globalisation and roving bandits means the demand from growth must be matched in alternative ways - substitutions perhaps. According to Berkes et al., 2006, the solution lies, ultimately, with the local populations, but the problem must be approached on multiple scales.

• Continuous monitoring of trade and resource trends to ensure the problem-solving practices are consistent with local behaviour/activities
• Align individual self-interest with long-term health of the resource 
• Compare cost of regulation with cost of losses if no actions were to be taken

Basically, no single approach can solve the problems of roving bandits and globalisation: people are terrible at sharing common-pool resources. Combined approaches may slow down the exploits of roving bandits however, and replace destructive incentives with a resource rights framework that encourages environmental stewardship.

Failure of single-species stock assessment

There are four key broad problems with single-species assessments, as described by Pauly et al., 2002:

• Assessment results have often been ignored on the grounds that they are not precise enough to use as evidence for the economically painful rsetriction of fishing practice: a.k.a. the "burden of proof" problem.
• Assessments have failed and grossly underestimated the severity of stock decline in conjunction with the depensatory impacts of fishing during the decline. 
• Too little attention has been given towards regulatory tactics; reasonable management targets have been produced through modelling and study, but have not been implemented, even in the short-term.
• Cultivation and depensation effects result in recruitment failure after a severe decline, which is associated with changes in feeding interactions, particularly when predators or competitors are removed: this produces an alternate stable state ecosystem with severe implications for fisheries management. 

It all leads back to the tragedy of the commons: increases in fishing-fleet capacity advanced the overcapitalisation of the world's fisheries, particularly due to their open-access nature. Common-pool fisheries (amongst most resources) are not managed cooperatively. The basic theory of bioeconomics suggests that if fleet reduction (reducing the amount of active fishing vessels) is done properly, then an increase in net benefits from the resources would be produced. Taxing the net benefit increase from the remaining fishers could then be used to support fishers who had to stop fishing. 

Instead, what is currently happening is that taxes are taken externally from the fishing sector in order to maintain biologically unsustainable levels of fishing, and this is supported by the public at large because it seems that there is this underlying general opinion that the oceans will yield as much as we need - just because we need it. What we actually get is a variety of different forms of extinction.

Local extinction: Defaunation can drive species in to local extinction, and is particularly severe amongst large pelagic fishes, 90% of which experience range contractions. This range contraction often results in the direct elimination of vulnerable subpopulations. For instance, consider the Asian tigers, who have lost 93% of their historical range, while the tiger shark, which its much less extreme range constriction, still roams the world's oceans (McCauley et al., 2015). 

Ecological extinction: Reduction in population abundance can filter through an entire trophic system; for example when marine vertebrates have decreased in abundance by 22%, fishes have declined in aggregate by 38%, and baleen whales by 80-90%. These declines are termed ecological extinctions, and on land this process leads to the phenomenon of 'empty forests.' Ecological extinction of forest fauna alters tree recruitment, plant dispersal and causes population explosions of small mammals. 

Commercial extinction: This occurs when species drop below an abundance level where they can be economically harvested - it might be considered ironic that a commercial extinction might be what saves a species, from a "you're dead to me" perspective. This is not always the case and not all species are so lucky to be spared once they stop being economically viable - some species may become highly prized as soon as they become rare; their value increases as the anthropogenic Allee effect takes grip.  

The Questions of Sustainability Science

How can we better represent the coupled system that is nature and society

within models and conceptualisations designed

to present the landscape system, human system, and sustainability?

How are modern cultures responding and learning from emergent long-term

 trends between the environment and human development, regarding the 

sustainability of the human-landscape system?

How can the vulnerability or resilience of individual ecosystems and

human livelihoods be recognised within the coupled system,

and how may they be managed?

Can a model or set of boundaries be produced that could

predict the degradation of an environment according to current 

activities and the socio-economic/environmental climate?

What is the best approach to direct the human-landscape system

towards sustaibability? Appealing to the market, governance,

culture or scientific field?

How can modern operational systems for monitoring and reporting on 

environmental and social conditions be integrated

to provide more useful guidance for efforts to navigate

a transition toward sustainability?

HOw can independent activities of research planning, monitoring, 

assessment and decision support be better integrated in to systems 

for adaptive management and societal learning?

Further reading: Kates et al., 2001. Science's Compass: Sustainability Science. SCIENCE Vol 292 

Western Parasite Behaviour: Repeating the mistakes of the past

In this entry I am looking to explore how we, as humans, try to exonerate our species with a variety of scapegoats that diverts attention and blame away from our own activities. 45,000 years ago, Homo sapiens was not particularly bothered about how they came off as a species, and the historical record presents our species as an ecological serial killer (Harari, 2011, p.75).  Within 2,000 years of the arrival of Homo sapiens in to North America, the continent had lost 34/47 genera of large mammals - Harari described the movement in 10,000BC as 'the human blitzkrieg.' Of course, in our more primal evolutionary days, this was simply the mark of an animal exceedingly good at adapting to a wide range of environments, and surprising the bountiful megafauna with the deadly intelligence and superior handicraft encased in a physically meagre body not worth particular attention.

Homo sapiens habits have not changed that much, and we continue to make excuses for what might be regarded as bad behaviour. This has emerged in the concept of 'weak sustainability,' and it is even more important that this concept is swallowed, since the true result of the exploitation it excuses has, often times, decimated a human population's ability to survive in its long-standing environment: the resource-draining Western society has on multiple occasions shrivelled the carrying capacity of many environments that support other human populations. Here, the concept of 'weak sustainability' in the context of neoclassical economics is explored and critiqued, based on a paper by Gowdy and McDaniel, 1999.

Weak sustainability: An economy is sustainable if its capacity to generate an income for future generations. Weak sustainability is achieved if an economy saves more than the combined depreciation of its total capital, even if it is drawing down its stock of natural resources (Gowdy & McDaniel, 1999, p. 333). 

Weak sustainability: Z (sustainability index) = [(savings/income) - (depreciation of manufactured capital/income) - (depreciation of natural capital/income)] x 100. If Z > 0 , than an economy is weakly sustainable. 
Notice the problem with this? According to this equation (Pearce & Atkinson, 1993), Japan, Costa Rice and the Netherlands are the most sustainable countries in the world. They have high savings rates and low rates of natural capital depletion. Japan and the Netherlands have completely destroyed their original natural environments, meaning their depreciation of natural capital is incredibly low. There is nothing much left to depreciate. Further, a country with a low income because it has run out of capital will generate a higher overall score. The flaws in this equation make it night impossible to run a negative score: this means every economy is, by the standards of Pearce & Atkinson, at the very least weakly sustainable.

Case Study: The selling of Nauru

Nauru is a central Pacific island with a circumference of ~20km, and originally supported a human population of around 1,000, who were subsistence livers dependent upon the bounty of the natural environment, and lived, for the most part, within the carrying capacity of the island. In 1886 however, it became a German possession, and shortly after, phosphate was discovered on the island. From 1907, 630,000 tons of phosphate was mined from the island, worth around £1,000,000 - the Nauruans received at most £1300 - 1/700th of its value. 80% of the island (a plateau called Topside) now looks like this: 

(https://turismifannklubi.wordpress.com/2013/11/03/evaluating-destination-nauru/)

The phosphate was scraped from between columns of ancient coral, and the mined areas are completely inaccessible, unusable for human habitation, or anything else that might support the local community. Eventually, a local market formed and with the increasing population, even fresh water had to be imported (Gowdy & McDaniel, 1999, p. 335). Imported food replaced all natural capital, to the extent that diet-related health problems became prevalent: 50% over 50's suffer diabetes, and high rates of heart disease/hypertension have been reported.

But Nauru IS sustainable according to Pearce & Atkinson's equation from 1993.

Phosphate mining was the only intensive manufactured capital, economic activity on the island: when it crashed in 2000, the depreciation of the manufactured capital became negligible. As had the natural capital already. This gives the island a sustainability index of 33. Weak sustainability depends upon substitution of capital when manufactured or natural stuffs becomes depleted, which in our economic system comes principally in the form of trade. For Nauru, this means the people live off of the interest generated by a trust fund created on their behalf - one bad investment or financial crisis in one sector could dramatically reduce the fund and jeopardise the community. Their health depends not on the local resources, but on the stock market values, and whims of individual investors - natural environments are steady and unchanging; market economies are volatile and unstable.

Gowdy & McDaniel highlight whilst the consequences of such violent exploitation are easily recognised on such a small island nation as Nauru, this same fallout is also occuring all over the world; consider logging part of a rainforest in Indonesia, or developing land in New York.

It has long been a human habit to increase growth, then substitution and technological complexity as resources degraded and collapsed: the more the natural world is devastated, the more reliant our populations become on the manufactured world we build. Money, it has been pointed out, cannot be converted back in to extinct species.

Is our modern society different to that of the ancients? Or any different to our BC habits as Homo erectus, Homo floresiensis, or Homo neanderthalensis?

Marine Conservation: The Basics.

Human activities have exerted an incredibly significant influence over the marine sphere; the coastal margins are undoubtedly affected the most by human activities, particularly around river mouths, where there are greater opportunities for ports and commerce. It is impossible to cover the range of human activities detrimental to the marine environment in one blog post, but the documented responses may be better explored.
What is Marine Conservation? What does it mean to 'protect' or to 'conserve?' And what is the marine sphere?

The marine environment is a source of employment, and contributes a substantial amount to the UK economy - the Firth of Clyde supports the incomes of 75% of nearby coastal populations. The social and economic benefits gained from the marine environment are inexorably connected to its quality - therefore it demands maintenance.

Fisheries 

The exploitation of marine species has caused large-scale changes in populations of predator and prey species throughout the world's oceans. The secondary effects of fishing are just as diverse as the number of fishing techniques used: consider by-catches of marine mammals, seabirds, fish and invertebrates, or ghost fishing by lost nets. Further, habitat disruption, changes in predator-prey relationships and distruption to the benthic zone. Artisanal fishers in the tropics use poisons such as arsenic, drive netting and blasting which causes direct damage to reefs. 

The crisis of over-fishing is well-known, and approached with no-take zones, statutory restrictions on fishing effort and gear used, and replaced in some instances with aquaculture. An example of fish stocks is that of the North Sea Cod, which as declined rapidly from the 1980's to today. In response to that, in the North Sea there are limitations on the amount of allowable sea time per vessel, and catch effort. There are also limits towards catch weight, a minimum mesh size of nets, a max. net size and attempts to zone the ocean. 

White alabone, Haliotis sorenseni are highly prized by gourmets and are harvested by divers in the shallow, inshore waters of California - it is a classic example of over-exploitation leading to a massive crash in population, which happened in the early 1970's. The Haliotis sorenseni has shown no signs of recovery, because in common with many marine invertebrates, this species releases eggs and sperm in to the water column. The reproductive success of the females is connected to the distribution, abundance and synchrony of spawning males. However, for the white alabone, the population was exploited to the point where individuals were too dispersed for successful reproduction, leading to a continuous decline.This negatively density-dependant phenomenon is known as the Allee effect. 

               

Biological diversity describes the variety/variability of living organisms and the ecological complexes in which they occur; diversity is defined as the number of different items and their relative frequency. 

Going completely the other way is the case of the Sandeels (Ammodytes marinus), which are fundamental for fisheries, are used for human consumption, livestock and as food for salmon fish farms. Its exploitation has been completely unregulated, and seabird breeding in 2004 was the lowest on record, because the birds also depend upon it as a food source. But there has been very little.

Lundy Island is a better case example: it is a designated no-take zone in New Zealand, and once this was implemented in 1977 by 1993 lobster population densities were 8x more dense. Lobster population has increased by 200% in 18 months.  

Aquaculture 

Britain's first cod farm may be found in Vidlin Voe, Shetlands. Its annual output is aimed at 2,000 tons a year. Three farms were proposed for the Island of Arran, and salmon farming is widespread around the west coast of Scotland, although sales have slumped due to health scares of disease. Whilst it is thought by some that fish farming reduces fishing pressures on wild stocks, there may be implications to wild populations due to escapees. The pollution effects first of all of the hormones injected, alongside parasites and disease all have significant detrimental impacts on wild species when introduced by captive breeds. Fish food requirements such as the sandeel case have proven negative impacts, and the waste/food impacts must all be accounted for. 

For this very reason, WWF aims to create stable marine networks that encompass 100 marine protected areas, and recognises that it is equally important to end destructive fishing practice, stop illegal trade in marine wildlife, and reduce land/sea pollution. The Marine Nature Conservation Review in 1987 on behalf of the conservation agencies was established to encourage the provision of protection to species and habitats considered under threat or in decline.

The Ecosystem Approach

Top-down control has been proven ineffective overtime, hence the ecosystem approach. This involves integrating marine conservation with sustainable social and economic goals. Objectives are set for marine nature conservation alongside the full range of human activities and demands. This is a switch from the traditional approach to focus only on rare/threatened features and instead encompass all ecological components of the system, particularly the functional processes that support them. This is what the Marine Nature Conservation Review focusses on, alongside how overarching policy goals could be translated in to action to improve conservation quality. 

The Working Group

The Working Group recommends the Government should apply an overarching policy framework of goals, objectives, targets and indicators to apply to all elements of its strategic goals for the marine environment. The Review tested a framework to address marine nature conservation at five spatial levels: the Wider Sea; Regional Seas; Marine Landscapes; Important Marine areas and Priority marine features. 

From this, they recommended that the government establishes conservation objectives at each level of the marine nature conservation framework in order to create an ecologically-coherent and representative network of MPA's. Policy and legislation should be introduced as is appropriate, and procedures to assess human impact should be maintained to determine the appropriate strength of response. 

The Habitats Directive and Birds Directive (Berne Convention) 1979

This was a European initiative designed to protect biodiversity through the conservation of natural habitats, wild plants and animals. The framework provides for the creation of a network of protected areas across the EU, to be known as Natura 2000 sites: SAC; SPA's and SSSI. 

Hydrothermal Vents: Hostile Environment II

Hydrothermal vents in the deep sea bed support anomalously large biomasses, and are a relatively recent discovery - the first vent was found in 1977 by ALVIN. They are associated with depths of 2000-3000m and issue water rich in bacterial floc at up to 350C. At the prevailing pressure, the water does not boil until 450C.
They form along the Mid-Atlantic ridge, amonst other expansion and subduction zones, as water is cycled down through cracks in the benthos, is heated by a magma chamber or dike, and cycled back up at a reduced density owing to the temperature increase. The water, now filled with elements and minerals as it has filtered through the rock, re-emerged in a mega-plume with steady venting.A smoker may be black or white depending on its chemistry.

Hydrothermal Vent Life

There IS light down at the vents, in the form of crystalloluminescence - seawater quenches the 350C brine, and so dissolved minerals re-crystallise, causing a luminescence effect. In chemiluminescence, energy is released by chemical reactions in the vent water, enough to emit light, but not to produce significant quantities of heat. During triboluminescence, mineral crystals crack from the cold or bang together in the turbulent erupting plume, and a flash of light is produced from the friction, impact or breakage. Somoluminescence is the luminescence that is excited in a substance by the passage of sound waves through it - in the deep, this is primarily what happens when microscopic bubbles in the hot fluid collapse. This light energy is not enough for any living organism to be able to depend upon. Instead, sulphur is utilised in chemosynthesis. The Anglerfish uses bio-luminescence to attract and confuse its prey!

                                   

The metabolic rate of abyssal bacteria is 100x slower than that of bacteria at atmospheric pressure, same temperature but maintained in the dark. This was discovered when the water-filled, sunken ALVIN was recovered after one year of submergence, and an exposed lunch was found to still be in perfect condition! 

A hydrothermal vent is colonised by the vestimentiferans - huge worms, which in this case are Tubeworms. Jericho worms, Avinella pompejana (Pompeii worm) and small crustaceans then appear, before the appearance of the Riftia pachyptila worm species, amongst further crustaceans and Zoarchid fish. 

                      

The Pompeii Worm (Alvinella pompejana) lives in the highest temperature known for any higher organism: their head stays in the seawater at 22C, but their butt is rooted in the vent water at 80C. It also has a carpet of bacteria on its back. Riftia pachyptila ingest a significant quantity of bacteria in to its trophosome, a special tissue that forms half of its body mass. 

The fauna is dominated by animals with chemoautrophic bacterial symbionts that oxidise the various reduced compounds issued from the fumaroles - sulphides, sulphur and thiosulphates.

Giant white clams were the first vent animals discovered, and they live on nutrients produced by symbiotic bacteria in their gills; they wedge their muscular foot in to cracks where vent fluid wells up. The Deep-sea mussel is knwon as Bathymodiolus thermophilus. 

Galatheid Crabs/Bythograea thermydron alongside the spider crab also colonise hydrothermal vents.

Hydrothermal Vent shrip - Rimicaris exoculata will feed on copepods and amphipods (opportunistic animals), but their main nutrition is from the bacteria they farm on large gills. It scrapes off this bacteria with modified clays, and has a dorsal organ which may be a far red eye. 

Zoarcidae fish including Thermarces cerberus feed on amphipods such as Ventiella sulfuris, as well as limpets, brachyruan crabs and copepods. 

Feeding

The larger macrofauna are broken up in to a few feeding types; deposit (ooze) feeders, suspension feeders and carnivores-scavengers. However, species cannot be definitively assigned to any of these, since some deep-sea bryozoans and ascidians are deposit feeders, whilst their shallow-water relatives are suspension feeders. Bivalves and ascidian tunicates may be macrophagous predators.

The mobile and wide-ranging scavengers and carnivores are far less abundant than the detritus-feeding types, but when carrion appears, ophiuroids, crustaceans and fish accumulate around it very quickly. The first to the scene is usually the Hagfish, of the family Myxini. 

Croppers are organisms that roam over the deep-sea bed cropping any food organisms they can find. Mobile deposit feeders may act as croppers, and ingest smaller deposit feeders. Gigantism is widespread amongst the opportunistic scavengers and predators. Croppers maintain the benthic prey species populations below the carrying capacity of their habitat. This means the croppers prevent competition for food amongst prey, competitive exclusion and dominance by a few superior species. 

Hagfish are disgusting. 

Extreme Marine Habitats I: Antarctica

A brief bit of background info on Antarctica: it is surrounded by the Weddell Sea in the north, and in the South, the Ross Sea fills a noticable inlet. The Southern Ocean surrounds its entirety, and in the winter (August time), its continental ice sheet extends out to the sea. Or so I'm told. It definitely used to anyway. But slamming humans and climate change and the Day After Tomorrow future is for another blog another time.

Antarctic Marine Biota

Understandably, the diversity in this hostile region is pretty low, but the primary producers include planktonic algae - chiefly diatoms, ice algae, benthic algae and some microalgae. Consumers include krill, soft corals, annelids, molluscs, crustaceans, fish, birds and marine mammals.

DONE!!

Kidding. 

The food chain in the Antarctic is pretty simple, but starting with primary production, benthic algal biofilms form on sediments and ice. An example of ice algae includes Melosira arctica. Macroalgae includes Phyllophora antarctica. Unsure why it's not Melosira antarctica. 

Euphausia superba, or krill is a keystone organism in the system, and it is commercially fished for human foodstuffs. Dense swarms of up to 10,000 individuals per square meter can form, and these swarms are dynamic, swimming closer to the surface in the night time. Swarms do not mix, have different sex ratios and different sizes. They have pleopods (swimming legs), upon which grow thoracopods with rake setae, which translates to filter-feeding appendages. They feed on sea ice algae by scraping the algae off with their rake setae. The algae is crushed and digested in the hepatopancreas. It takes three years for them to mature, and they release fertilised eggs which hatch in to nauplii, and these slowly ascend the water column over three year, if they are not hiding in ice caverns. 

Other invertebrates include molluscs; Adamussium colbecki (Antarctic scallop), Neobuccinum eatoni (Antarctic whelk), and the Tritonia antarctica that lives upon the Alcyonium antarcticum - The Tritoniid nudibranch upon a soft coral.

Cnidarians include the Desmonema glaciale, or Scyphomedusa spp., alongside the Trachymedusa spp. 

Echinoderms include the Ctenocidaris perrieri or Pencil urchin, and the Odontaster meridionalis (sea star) which eats Perkinsiana spp., - featherduster worms. 

Antarctic fish have no swim bladder but are neutrally buoyant, and are also without haemoglobin, e.g. Chaenocephalus aceratis, or White crocodile fish. They have slower metabolisms, large gills and scale-less skin, with a high cardiac output and high blood volume. Pagothenia borchgrevinki fish have antifreeze - macromolecular antifreeze glycopeptides (AFGPs) that lower the freezing point of their body fluids beneath that of the seawater. It is synthesised in the liver, secreted in to the blood and distributed to body fluids. It prevents freezing by inhibiting ice crystal formation on fish interiors. Ice presence in the spleen of a fish indicates the spleen itself removes ice crystals from the fishes circulation. 

Ice fish are endangered owing to the heavy overfishing; 400,000 tonnes of Paraliparis devriesi were cought between 1969-1970. Notothenia coriiceps or Antarctic Cod is also incredibly popular in the fishing market. The Convention for the Conservation of Antarctic Marine Life Resources in 1982 (CCAMCR) was implemented, but despite this the Patagonian toothfish (Dissotichus eleginoides) and Antarctic toothfish (D. mawsoni) were still over-fished by the Japanese, who sold it as Chilean Seabass at $1000 per fish. On the longlines in which they were fished, over 191,700 seabirds were found dead.

Antarctic birds migrate away in the winter, exluding some penguin species. The Catharacta macormicki (South-polar Skua) replaces birds of prey in Antarctica, and feeds on Adelie penguin chicks and fish. The Macronectus giganteus, or Giant Antarctic Petrel is the largest flying Antarctic bird, weighing 5kg. It feeds on fish, offal and carrion, and arrives in late winter. Oceanites oceanicus or Wilsons Storm petrel is the smallest Antarctic bird, but has the longest migration, flying 40,000 km per year. It feeds off of krill and organic waste.

Penguins belong to the order Sphenisciformes, family Spheniscidae. The Adelie Penguin, or Pygoscelis adeliae)is the most abundant species, and 99% feeds on krill, nesting in rookeries. Its main predators include skuas and petrels, alongside Killer Whales and Leopard Seals.
Aptenodytes forsteri, or the Emperor Penguin, is found on the Antarctic coastal ice zones, where it resides and mates once a year. The male incubates the egg in the winter within a large colony, and the females return in July, before both parents feed the young.

Marine mammals include seals and fur seals e.g. the Weddell Seal and the Ross Seal, fairly easy to remember. The Leopard Seal is the top predator here. A large range of cetaceans also exist in the Antarctic.

Marine Mammals

To continue the saga of tragic high-intensity exam cramming, I have moved on to marine mammals, which nearly concludes this module: Marine Ecosystems. I may well update these with inserts from extra reading I've not already included over the next few weeks, but for the moment I am highly anticipating the end. Gotta say. Not that marine biology isn't interesting. It is. Good to know what you want to conserve and study before you try and well, conserve or study it. Too bad trying to remember the latin is about as easy as removing your lungs, stitching them to your back and using them to fly backwards around the Earth in order to reverse time and give yourself a little bit more leniency to memorise the crap out of the marine world.
Anyway.

Marine Mammals. 

Screw you.

A mammal is a higher vertebrate with a well-developed brain and neural system. It is warm-blooded with homeostatic control in order to ensure a maintained core body temperature. They give birth to live young and feed this young through mammary glands. They breathe air and contain epidermis with hair. Marine mammals must be able to swim and dive to great depths in many instances; be able to control their body temperature as they are doing so, all the while often supporting offspring.

Marine mammal taxonomy

• Pinnipeds - seals, fur seals and walruses. There are 33 species of pinnipeds, and they all have an amazing ability to dive up to depths of 1500 feet, and can hold their breath for 2 hours straight. The Caribbean Monk Seal was hunted to extinction in 1952 - humans love(d) them. 

Seals have an internal ear with no external features, just a closeable hole; they have clawed front flippers, whcih are all they walk with, and they swim with their hind flippers. They are mainly polar animals, and the arctic seals haver a wide range of threats including commercial fishing, pollution, and other predators. Antarctic seals have reduced problems with predation, pollution and fishing however, under the CCAS (Convention for the Conservation of Antarctic Seals). They control temperature with blubber and blood circulation, the former being rich in fatty oils to insulate and provide a rich energy source, the latter constrict to reduce periphery blood supply. They have a high oxygen store in blood and body tissues, 4x that of a human athlete, and bradychardia - the slowing of the heart whilst blood pressure is maintained, and this is all to facilitate diving. Usually each mature female will have one pup per year, give birth on land, and feed the pup with milk that is up to 50% fat. A dominant male will have a hareem of females. Arctic seals feed upon cod, shrimps and squid; bearded seals feed upon shrimps, crabs, clams and whelks; Antarctic seals meanwhile almost solely feed upon Krill. 

Phoca hispida - Ringed seal: digs holes in the ice sheat up to 7ft thick, offspring weaned in 2 months.

Erignathus barbalus - Bearded seal: Head-rams the ice to make holes, pups can dive 200ft after 1 month, weaned in 3 weeks. 

Lobodon carcinophagus - Crabeater seal: don't eat crabs but have ridged teeth to filter krill.

Hydrurga leptonyx - Leopard seal: top predator up to 12ft long, weaned after 3-4 months. 

Phoca vitulina - Harbour seal

Phoca caspica -  Caspian seal

Fur seals and sea lions have ears that extend out from the head, use their longer front flippers for swimming and rear flippers for walking. They're found in the N. Pacific, Australia and New Zealand. Sea lions (Otariidae) include:

Eumetopius jubalus - Stellers Sea lion

Neophoca cinerea - Australian sea lion 

Fur seals (Actocephalinae) include: 

Callaorhirinus ursinus - Northern Fur Seal

South African and Guadalupe Fur Seals 

80% of the Pacific Walrus (Odebenus rosmarus) population reside in the Bering sea in the winter, but females and immatures move north in to the Chuckchi Sea in the spring, whilst males migrate south. Their principle food is clams.

• Carnivora - polar bear and sea otter: Polar bears (Ursus maritimus) are distributed circumpolar around the ice pack, mainly on landfast ice and floe edges. They have no natural predators and are controlled by the abundance of prey, and the hunting of man. Sea Otters (Enhydra lutris) weigh the same as Kylie Minogue - 45kg, and have the thickest fur in the animal kingdom. They sleep in the water and roll up in kelp at the surface to prevent drifting off. They are a keystone predator to maintain the kelp system free of over-grazing by urchins, but also feed off of mussels, clams and abalone. They are threatened chiefly by habitat loss, oil spills, pollution and hunting.  

• Sirenians - manatees and dugong: vegetarians that may eat up to 15kg of sea-grass a day, and are found in salt, fresh and brackish waters. They are solitary animals, the mother-calf being the only social bond. The gestation period is one year, therefore reproduction rate is quite low, females giving birth every 2-5 years. Chief threats include habitat loss and boat collisions. 

Trichechus manatus - West Indian manatee

Trichechus senegalensis - West African manatee 

Trichechus inunguis - Amazonian manatee

Dugong dugon - Dugong

• Cetaceans - whales and dolphins. 

Whales may be split up in to the Mysticeti and Odontoceti - baleen and toothed. The Mysticeti whales have no teeth, but keratin baleen plates suspended from the roof of the mouth, alongside two nasal openings in a symmetrical skull. They have no echolocation capabilities, with the melon only being present in the foetal stage. Odontoceti have teeth - up to 250 in some dolphin species, and a single nasal opening in an asymmetrical skull. The melon is well-developed and plays a major role in echolocation. Their taxonomy is constantly under review, based on genetic analysis of their ribosomal RNA sequences, which has suggested Odontocetes, Sperm Whales, may be more closely related to the Mysticetes.

Echolocation and Vocalisation

There is discussion as to whether echolocation/vocalisation is communication in the form of language, or akin to that of bird song. The clicks and whistles of dolphins (echolocation and communication) have distinct signatures, and dolphins can imitate the whistles of others to attract their attention. In captivity, dolphins will imitate the human voice so well local accents can be detected. Male dolphins are better at imitating and have a signature close to its mother; females are more distinctive, owing to the social grouping, where females remain in the pod. It is much the same for Sperm Whales. Whale song typically lasts 20 minutes or longer, and is then repeated. It may be changed completely between breeding seasons, potentially to increase the attraction of females - maybe the last song just didn't cut it!! 
Blue Whale vocalisation is composed of trills and moans, called A-calls and B-calls. They have a very low frequency of 10-39Hz, nothing humans can hear. Megaptera novaeangliae (Humpback Whales) range from 30 Hz - 8 KHz, using moans, grunts, blasts and shrieks. In Mysticetes, air is moved from the lungs, and the nasal/larangeal sacs act as resonators. In Odontocetes, it is less well understood, but sound is produced by two pairs of phonic lips in nasal passages, not the larynx. The phonic lips are connected to the dorsal bursa, organs which vibrate when air passes through the lips. Most species have two sets of phonic lips and dorsal bursa. Sperm whales and other Odontocetes use a similar method but have Spermacetti instead of dorsal bursa.

The melon structure found in the forehead of Odontocetes focuses sound waves, since water is denser than air, so sound waves travel 5x faster. They detect reflected waves through the mandibular nerve, transmitting the signals to the brain.
Ocean waters are stratified due to surface warming by long-wave thermal radiation, forming distinct layers around the thermocline. The buffer zone of the metalimnion just below the thermocline is ideal to transmit sound waves slowly over longer distances, because due to refraction, the sound waves are entrained in the buffer zone and transmitted horizontally in all directions. Whales take advantage of this in breeding season.

Ecology and adaptations of Cetaceans 

They have an aquatic lifestyle, feeding mating and giving birth in the water. They have complex hunting and feeding methods, with vocalisation including echolocation, and a complex community structure. Only Baleen whales are solitary but can form feeding groups, if only for a few hours. Methods of feeding include bubble nets, used by Humpback Whales; kerplunking by Bottlenose Dolphins, and listening by Killer Whales. 

Mysticetes: Feeding and prey

Mysticetes are batch feeders, that gulp and create a suction in the rear part of their mouths to draw in water; this the Grey Whale and Blue Whale does. They also skim a continuous flow of water through their mouths, such as the Pygmy Right Whale and Bowhead Whale. Mysticetes feed upon krill and other zooplankton, alongside cephalopods and fish. 

Mysticetes: Feeding and prey

Odonticetes are raptorial, grabbing their prey with rapid swimming motions, but they also use oral or larangeal expansion to draw in prey. The Delphinidae feed upon cephalopods; Phocenidae feed upon cephalopods and fish; Ziphiidae feed upon cephalopods; Monodonticidae feed upon fish, cephalopods and benthic invertebrates. 

Threats

• By-catch from fisheries; porpoises and dolphins in particular are threatened by this.
• Food competition between dolphins and porpoises
• Cetacean Decompression Sickness, which is linked to active sonar blasts that interfere with their orientation and communication.
• Phocine Distemper Virus, amongst other diseases. 

Coral Reef Ecology

Coral reefs are generally acknowledged as one of the most threatened ecosystems in the world, as well as one of the most vital. They are of critical significance for humans through their provision of subsistence food for many coastal populations, and serve as a primary coastal protection structure for most tropical islands. They are also a major pull factor for tourism and foreign exchange earnings - the value of living resources and services provided by reefs is an estimated $375 billion annually. They further provide a habitat for some of the greatest biological diversities in the world. 60,000 biotic species have been identified within the reefs, but an estimated 423,000 exist.

Reefs are described as "an oasis in a nutrient desert," and occur in oligotrophic waters, but are three times as productive as coastal upwellings. Reefs are not found on western continental coasts as the Coriolis gyre brings cold waters on to the coastal region, e.g. East Africa has fringing coral reefs, whilst West Afriac does not. Their optimum temperature is 23-25C, and they typically occur in warm oceanic currents such as within Bermuda.

Reef development

There are two primary types of coral: order Hexacorallia (hard corals) and order Octocorallia (soft corals). They are cnidarians, multicellular, simple organisms of the lower Metazoa, and have nematocysts for predation and defence. Once a nematocyst has been fired, they regenerate within a few hours. Scleractinic reef-building corals undergo extensive calcification processes, and they are called hermatypic corals - meaning reef-building and symbiotic. A colony is called a Coenosarc, and growth results from polyp division and the gradual accumulation of calcium carbonate between corallites, alongside growth from Stolons. This is a root-like growth that polyps grow out of and lay down cellular layers on the substratum. Monopodal growth describes the development of a young polyp trunk from an old polyp. Sympodal growth describes young polyps growin at the edges of older polyps, and dychotomic growth occurs from the symmetric division of polyps.  

                       

Asexual Reproduction

This is the main cause of colony growth, and occurs through three main processes. The first is fragmentation, which occurs mainly in unfavourable conditions or following storm damage: an entire colony branches off to form a new colony. In budding, new polyps 'bud' off from parent polyps to form new colonies. Colony fission can also occur. The polyps may divide longitudinally, wherein the polyp broadens and divides longitudinally, leading to the growth of two smaller polyps. Transverse division may also occur where the polyp divides horizontally, and one polyp forms from the mouth region, one from the base. Intratentacular budding occurs where a new polyp forms from the oral disc of an old polyp. Extratentacular budding describes the formation of a new polyp from the base of an old polyp. 

Sexual Reproduction

"Broadcasters" are spawners in hermatypic corals, and around 75% of all known coral species spawn positively buoyant gametes at very specific times so as to ensure fertilisation. Many coral species may mass spawn within a narrow time-frame, and intra-species fertilisation is common, although mass spawning raises the possibility of hybridisation by congeneric species. Mass spawning is vulnerable to catastrophic events, and can smother corals.

Brooders are ahermatypic corals that live in disturbed, nearshore reef zones. Here, sperm, but never eggs are released in to the water, and brooding produces mature, often negatively buoyant plantulae ready to settle, e.g Favia fagum. The larvae float to the top, sink back and settle, before metamorphing in to a founder polyp to become another colony. Acropora spp., release brooded larvae. 

The time of spawning is affected by:

• Sea temperature
• Lunar cycle
• Day length
• Irradiance
• Wind and currents
• Rainfall
• Chemical stimuli
• Latitude (higher latitudes have shorter breeding seasons)

Spawning corals:

• Montpora spp., - a broadcaster that spawns between 8-10pm following a new moon in June and August.
• Porites spp., - a broadcaster from 11pm-1am following a full moon from June to August.
• Pocillopora spp., - a brooder that follows the lunar cycle, releases fertilised eggs throughout the year.
• Acropora spp., - a brooder viviparous in nature that releases planulae (see mangal communities for more info on viviparous flora). 

The Algae

Scleractinian (reef-building) corals are highly dependent on zooxanthellae such as Symbiodinium spp., symbiotic single-celled algae that provide 95% of the carbon required by the corals for growth, reproduction and maintenance. They have an outer membrane that is thin and leaks metabolites, which is beneficial for the coral polyp, which can harness all that is leaked. The algae becomes non-motile once it forms a symbiotic relationship with the polyp, therefore becomes more vulnerable and depends upon the polyp for structural support and protection. They are both highly vulnerable to environmental stresses that impact on the symbiotic relationship and often cause bleaching. 

                         

Reef types and morphology 

1. The lagoon: Has a sandy substratum, sea-grass beds e.g. Syringodium spp., and are important nursery grounds for reef fish, alongside echinoderms and holothuroidae. Halimeda spp., (green algae) are prevalent, and coral growth occurs from fragments broken off by wave and storm damage. Sea cucumbers are important to bioturbate the sediment and provide organics for other species. In defence they will eject their stomachs and evicerate. Black-tipped reef sharks (Carcharhinus melanopterus) is also commonly found here, alongside mushroon corals. 

2. The reef back: Inshore from the reef flat, this has limited water movement, therefore a higher turbidity and lower diversity. It is a habitat for massive corals such as Porites spp., alongside the hydroid fire coral Milepora spp., with a very powerful sting, alongside Octacorallia in the low-energy region e.g. Lobophyton spp. Giant clams (Tridacna spp.) are also found secreting calcium carbonate.

3. Reef flat: At low tide, this section is very shallow or even exposed. The coral is generally branching, for example dominantly Acropora spp., and is home to Damsel fish, Butterfly fish, Surgeon fish and Parrot fish, alongside a tummult of invertebrates - bivalves, gastropods, crustaceans, and porifera.  

4. Reef crest and reef front: The crest is quite shallow, with high wave action and no corals since it is frequently exposed: encrusting red algae such as Porolithon is more commonly found. Down the reef-front, fast growing corals such as Acropora spp., may once again be found, alongside the massive and encrusting corals. Competitor corals come in which are slow-growing and flat, tabular species, adapted to lower light levels. Larger Humpead Parrotfish, Jacks and Humphead Wrasse fish species are also found amongst oceanic fish, turtles and marine mammals. 

                        

Species Interaction

Species mutualism may be seen between predatory fish and the Labroides spp., which are small, cleaner fish. The Trapezia crab spp., defend their host coral Pocillopora against the invasive, grazing asteroidae Acanthaster spp. Clown fish also lay residence within anemones - Hetractic spp. 

Threats to the systems

The primary natural pressure is grazing from urchins such as Diadema spp., and the Crown-of-Thorns starfish, Acanthaster planci, A greater threat however, is bleaching.

Bleaching occurs when the coral animals expell the zooxanthellae out of stress, alongside their photosynthetic pigments. Stresses that cause this include freshwater flooding, pollution, sedimentation, disease, increased or decreased light and elevated sea surface temperatures. In such an event the corals may lose up to 90% of their zooxanthellae, and the zooxanthellae themselves may lose up to 80% of their photosynthetic pigments. This may be recovered from, but prolonged or extreme exposure can result in the mortality of entire reef assemblages. 

CASE STUDY: The Live Reef Food Fish Trade: Cyanide Fishing in Indonesia.

The LRFFT has rapidly expanded throughout SE Asia, and the trade concentrates on groupers such as Plectropomus spp., and Napoleon wrasse (Cheilinus undulatus). These top-predators are long-lived and slow-growing, but the overexplotiation of target species is not the key stress on coral reefs: the method of capture is. Cyanide is applied to stun the fish, causing severe reef degradation from secondary bleaching and polyp death. The estimated loss in live coral cover from cyanide fisheries for food is between 0.05-0.06m^2 per 100m^2 per year. However, this estimate should not be taken optimistically, as coral cover recovery does not equate to a return to a healthy state of being, and the longer-lived hard corals such as Porites spp., struggle much more to recolonise an area. Further, removing top predators significantly affects the trophic cascade of the system, and the preferential removal of larger individuals affects the sex ratio and reproductive success of the exploited species, leading to a positive feedback loop. 

                        

Resistance: The ability of individual corals to resist bleaching or to survive after they have been bleached, or been subject to another such stress. This may be due to an intrinsic species/colony-specific tolerance or extrinsic environmental factors that afford some protection from the stress. 

Resilience:Stable states respond to change through their ability to absorb disturbance, recover or reorganise, and adapt to different circumstances. The speed of return to equilibrium after a disturbance.