An Assessment of Ocean Ecology: How Natural and Anthropologic Mechanisms Affect Ocean Populations

and Habitats

By

Justin F. Marcus

J. Marcus

Abstract:

This review discusses the several challenges that ocean ecosystems are currently facing due to human causes and fluctuations in natural cycles. The sections cover natural

oscillations in climate, chemical changes in the ocean, habitat manipulation, the changes in tropic flow, impacts of ocean fisheries and changes in genetic frequencies. Many of these issues can be indirectly or directly related to anthropogenic practices, while others can be connected to fluctuations of global cycles. Since the ocean is such a massive and dynamic ecosystem, it can be challenging to correlate particular affects with their exact

cause. Progressing our knowledge of the ocean will require an increase in the understanding of the ocean’s ecology and how species react to climactic, habitat and chemical changes. The goal of this review is to detail how each alteration affects the

ocean, and to show the interconnectedness of the ocean.

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1 - Introduction:

For human’s existence the ocean has provided an array of uses that are being

exploited. Macro and micro changes have occurred within our atmosphere and ocean

because of the intensive demands for products that the ocean provides. Geological shifts

in cycles such as El Niño Southern Oscillation (ENSO) and surface temperatures have

changed, which has altered several ocean ecosystems (Murphy et al. 2007). Ocean

habitats like coral reefs have been affected by the dumping of fish waste and physical

destruction from fishing gear dragged on the ocean floor (Bo et al. 2014). These

anthropogenic changes have created several issues for the population dynamics of ocean

organisms (Catherine et al. 2002).

Due to the ocean’s massive size, tropic levels are intimately related and each

species has an important part in the ocean’s productivity. This specialization is why

minor alterations to groups of organisms can become catastrophic to the overall biota

(Bacalso et al. 2014). Any localized change can have the potential to create regional

alterations that are detrimental to several populations.

Fortunately there has been an increase in ecological studies to discover the

sources of the ocean’s ecology. Many new technologies and breeding techniques are

being introduced in countries around the world to reduce the stress and waste put into the

ocean. Some of these technologies include aquaponics, which can occur both on land and

within the ocean. Aquaponics have been a source of food and reduce anthropogenic

harm to the ocean, however there are setbacks such as the limiting of gene pools and

increased spreading of diseases (Frost et al 2006).

There are several population dynamic issues that have occurred fishing has

increased in quantity and area. It is important for humans to decrease their use of the

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ocean in order for its habitats and populations to recover. This relief will also increase

population size, genetic pools, and limit artificial evolutionary selection by fisheries. The

increases of environmental stressors and anthropogenic harm affecting the ocean and its

inhabitance have the potential to compound collectively, and lead to an ecosystem

collapse.

2 – How Changes in the Ocean’s Chemical State Affect Organisms:

Several ecological communities in the ocean have been affected by habitat

manipulation. Climate changes have been responsible for several alterations to ocean

habitats. Studies have linked geological cycles (Murphy et al. 2007), ocean pH levels

(Richards et al. 2014) and ocean temperatures (Reist et al. 2006) to these changes in

climate, which have had varied negative impacts on ocean fisheries and primary

productivity.

2.1 - El Niño Southern Oscillation:

The ENSO weather pattern is an important and destructive climactic cycle in the

Pacific Ocean. ENSO historically has occurred every 7 years and varies in strength,

however recently it has been occurring every 3-4 years, and has increased in average

amplitude (Murphy et al. 2014). When it is not an El Niño year, cold water flows at the

bottom of the ocean from west to east (Australia to Peru), while the surface water of the

ocean is significantly warmer, flowing from east to west in a cyclical fashion. The

atmosphere affects this current’s flow as well. A warm front running east to west,

delivering a warm, wet and low pressure Australia; that then cycles back above the ocean

surface to Peru bringing a cold, dry and high pressure front (Dankos, 2009). The ocean

level is also higher in the west because warm water is less dense than cold water, causing

the east Pacific Ocean to have a lower ocean level.

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When it is an El Niño year, pressure increases over the Pacific Ocean’s surface,

causing for surface water to flow east, also bringing heavy storms. This event changes

the sea surface temperature (SST), sea level distribution and the direction of the current

in the Pacific Ocean. These changes impact ocean organisms’ lifecycles by altering their

environment and the dynamics of the ocean. (Collins et al. 2010).

Global warming has caused for an increase in the atmosphere’s temperature,

pressure distribution, SST and ocean currents (Collins et al 2010). Scientists believe

these changes correlate with ENSO events having larger amplitudes and occurring more

regularly (Murphy et al. 2014). If global warming continues, there will likely be more

frequent ENSO cycles with larger impacts, which will affect ocean organisms and their

habitats.

Sea Surface Temperatures:

Since the 1880’s there has been documentation of ocean temperatures.

Over the last century there has been a noted increase in the Pacific Ocean average

temperature (Zhang et al. 2007). Figure one shows this graphically.

Fluctuations of the Pacific Ocean temperatures in degrees Celsius from 1870-1980:

Figure 1: (Zhang et al. 2007)

Ocean temperatures fluctuate, however using climate models, carbon dating in

glacial ice sheets and historical data, scientists have found correlations between human

impact and these temperature increases. For example, the spike of temperatures in the

1880’s has been attributed to the industrial revolution using carbon dating (Wilson et al.

1992). This process is done by drilling ice cores, which have several layers, each of

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which containing a different isotope of carbon depending on age. Because carbon

decays, each isotope can be dated with accuracy up to 3-4 years, allowing us to discover

the amount of atmospheric carbon in each decade.

After World War 2 in 1945, the ocean temperature increases over the next 40

years to the highest in record. Those decades were during a time of increased

manufacturing and expansion in many countries, both of which increased the amount of

CO2 in the atmosphere. These anthropological actions have an affect on the ocean’s

temperatures (Zhang et al. 2007).

Temperature can have varied affects on different species. Negative affects on

species have been a decrease in stable population sizes, fewer species interactions, and

changes in their male/female life cycles (Murphy et al. 2007). A species that has been

studied for these issues is the Arctic Krill (AK), a keystone species in the Southern

Pacific ocean. A study by Murphy et al. used several years of recorded ocean

temperatures, sea ice concentrations and body length of AK to see what affects of

increased ocean temperatures had. Figure 2 below shows the data that was compiled.

Changes in krill biomass, abundance and size compared to sea surface temperature from 1990-2005.

Figure 2: (Murphy et al. 2007)

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Graph C (left) compares the abundance of AK, to the biomass of AK individuals

between 1990-2005. There is a trend that as abundance increases, biomass decreases;

and as abundance decreases, biomass increases. This suggests biomass and abundance of

AK are inversely related. For this to occur, AK would need to decrease their body size as

their population increased over time. Population trend occur often for all species,

however there must be an influence causing this trend (Murphy et al. 2007).

Graph E (right) shows the average length of AK, compared to SST off of

Southern Georgia from years 1990-2005. There is a trend in the graph as SST increased,

the average length of AK decreased. The relationship between AK body length and SST,

suggests they are inversely related. If this is true, increases in SST are potentially

harmful to AK, and possibly other species of the ocean (Murphy et al. 2007).

Combining these graphs, it is seen that SST increased, body length decreased, and

individual abundance increased over 15 years (Murphy et al. 2007). This relationship

should not be overlooked because SST is likely causing these physiological changes, and

SSTs are currently increasing (Dankos, 2009). If a new threshold of SST is reached,

there may be amplified changes to the AK populations, making it impossible for them to

survive, along with the other organisms they interact with.

2.2 - Deep Ocean Temperatures

Along with changes in SST and global climatic trends, the deep ocean has also

increased in temperature (Smith et al. 2009). SST often fluctuates due to its immediate

interaction with sunlight and the atmosphere. The deep ocean remains more stable

because the sea surface buffers these factors. Water in the deep ocean moves slower that

the sea surface, however it has a higher consistency of pH, pressure and temperature.

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Research conducted in the North Pacific oceans has found that deep ocean temperatures

are being increased, which is affecting the biota.

Smith et al. looked at mobile megafuana in the North Pacific from 1989-2004.

Median body size and population density were analyzed, all of which can be seen

graphically in Figure 3.

How changes temperature affects population density and body size:

Figure 3: (Smith et al. 2009):Blue circles represent density of populations; Red circles represent body size.

Using this graph, trends in population density, body size and temperature can be

seen. It should be noted that between the years of 1992-1996, there were normal

temperature cycles, while beginning in 1997 there was a change where temperatures

increased, which continued through 2003, afterwards decreasing slightly in 2004.

Although consistent data of species density and median body size was unable to

be collected for each year, population densities decreased from 1998-1999. Elpidia

minutissima (graph C) and Echinocrepis rostarata were both affected by temperature

increases in 1998. E. minutissima did not have a fast recovery from this change in

temperature. E. rostarata was able to acclimate to this temperature more readily. It is

possible that in an effort to maintain population size, E. rostarata reduced their median

body size to conserve energy, allowing for more individuals to spawn (Smith et al. 2009).

Comparison of different species’ ability to recover and alternate their physiology due to

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changes in temperature can be valuable for predicting how these organisms will survive

in the future, and estimate how other species might adapt as well.

Changes in Ocean Acidity:

Along with a change in ocean temperatures, there has also been a tread of ocean

acidity increasing (Richards et al. 2014). Acidity naturally increases with temperature,

however there has also been a rise in the amount of CO2 in the atmosphere. The ocean is

a reservoir for CO2, and has also seen an increase in the amount of dissolved CO2, which

increases acidity. This change in ocean conditions is likely to affect organisms’ life

cycles and habitats.

Off the coast of Queensland Australia there was a study conducted on several

shellfish to test their abilities to survive increased acidity. Organisms were checked for

calcification rates, physiological processes, lifecycle and hypercapnia (increases in

normal CO2 concentrations). All species of both prawns and scallops showed impaired

development and hindered reproductive abilities with increased acidity. Scallop species

had issues calcifying (sequestering calcium to build a shell) and surviving with increased

hypercapnia and acidity. Prawns were able to rapidly digest the high levels of CO2; and

calcification rates were unaffected or increased depending on the species (Richards et al.

2014). An increase in ocean acidity appears to negatively affect shellfish lifecycles,

however there are traits within some species’ genomes that allow certain characteristics

to acclimate and thrive.

Research suggests that the ocean is dynamic and fluctuates on its own, as well as

through human influences. Raised ocean temperatures and increased ocean acidity are

having negative affects on various ocean organisms. To allow for the ocean to regain its

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natural chemical and physical levels, there must be a reduction in the quantity of

contaminants that enter our atmosphere and hydrosphere.

3 - Manipulation of Ocean Habitats:

Fishing vessels do not always follow proper procedure, and often damage the

ecosystems they are fishing (Bacalso et al. 2014). There have been documentations of

dumping excessive amounts of by-catch, damaging coral reefs and not removing used

fishing gear from an area that is no longer being used. Beyond these issues, there are

several techniques that are destructive to ocean communities and their habitats by design.

These poor practices are occurring all over the world, and are collectively leading to a

polluted ocean with diminishing habitats for organisms to spawn and live.

3.1 - Trophic Flow Alterations

Fishers will target one species because specification allows them to sell their

product as one unit, which increase efficiency. Targeting of selected species can be

dangerous to that population because predation is increased for that organism and other

natural variables remain constant (Ban et al. 2014).

Research on fishing methods in the Danajon Bank (DB) of the Philippines looked

to see how removal of selected species could have larger implications. This study used

Ecopath, a program that is able to give flexible ecosystem models (Bacalso et al. 2014).

These models can show all of the interactions between trophic levels (TL) in this

community, as well as be used to predict changes in populations if variables remain

constant, increased or are introduced.

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37 organisms that spanned four TL were studied. Figure 3 below shows the four

TL within the ecosystem (y-axis), and the organism’s relative biomass (size of the

circles). Each of the lines represents the linkages of each species to another.

Trophic level flow in an ocean ecosystem:

Figure 3: (Bacalso et al. 2014).

This diagram depicts how entire ecosystems revolve around primary producing

species, and how interconnected ocean ecosystems are. The DB was also compared to

other reefs in the area to evaluate the productivity of the primary producers. It was found

that the DB had a lower total production per total biomass compared to three other fished

reefs (Cathrine et al 2002).

With an increase in harvesting 2nd and 3rd TL organisms, there was also a decrease

of organisms in the 4th TL. It is likely this has occurred because there is less available

food due to increased predation of the 2nd and 3rd TL (Bacalso et al. 2014).

The majority of fish that have been harvested in the DB were from the 2nd and 3rd

TL of their food webs. Their removal has likely lead to this increased in biomass because

there is less predation of primary produces. It is concerning however that even though

the primary producers have increased in biomass, their productivity has not. Speculations

behind this are that 1st TL organisms have reached their carrying capacity and expanded

to an unsustainable size (Barcalso et al. 2014).

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If the middle TLs continue to be farmed at these rates, their populations may

dwindle to the point that top-level consumers will be driven to extinction because of their

lack of prey. The ecosystem could collapse because of unnatural predation rates of the

middle TLs. (Barcalso et al. 2014). As ocean habitats are destroyed, increased

competition will occur for several species, creating a bottleneck allowing for few species

to survive.

3.2 - Physical Ecosystem Destruction

Like any habitat, physical disruption can create issues for the organisms living

within it. Much of the harm caused to ocean habitats is from fishing equipment in a

variety of ways. The affects of fishing tactics can vary from direct contact with the

physical habitat, or by the removal of keystone species that lack natural predators

(Cheryl A, 2010).

Studies have attached cameras to Remotely Operated Vehicles (ROV) to fishing

gear, to track the damage that it causes to ocean habitats, and assess the state that the

habitat is currently in. One study in the Mediterranean focused on the coasts of Italy’s

reefs, which are subject to several fishing operations. Using ROVs, they found excessive

amounts of non-biodegradable trash, much of which was discarded fishing gear that was

causing destruction to the reefs (Bo et al. 2014). This area is known for a large

biodiversity of several organisms, including corals. These coral forests are slow growing

ecosystems, and at the current rate of destruction they are unable to replenish, thus

leaving no habitat for the organisms living there. Tracking this progression and finding

methods to stop destruction will be important to conserve the biodiversity of this area.

New technology has increased the capabilities of fishing, allowing fishermen to

go deeper into the ocean by 350m since 1950 (Watson et al. 2013). This study looked at

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trends in how capabilities to access more of the ocean have affected species. There has

been a larger diversity of organisms fished by 40%, primarily from the deep ocean. This

increase is alarming and potentially harmful. Deeper sections of the ocean adapt and

replenish at slow rates. These areas are also more challenging for researchers to get to,

making it hard to study the health of the community. Deep-sea fishing allows for more

fish to be farmed, however there is little knowledge of several deep-sea habitats. It is

concerning because we cannot make accurate predictions on when or if these populations

will recover.

Habitat fragmentation in the deep ocean and its coral reefs is harmful to the

biodiversity of the world, because it has the some of the highest species diversity, and

preserved ecosystems that have previously been untouched (Pitcher et al. 2005). Since

these organisms have specialized niches, it is challenging to relocate them to a new

habitat. Organisms living in these habitats will likely face one of two outcomes: continue

evolution at increased rates to adapt to the new conditions; or natural selection will lead

to speciation or extinct. Conserving the habitats and biodiversity that these organisms

live in is essential for their survival.

3.3 - Fish Waste Dumping

Upon harvesting fish, many fishers discard by-catch, and the undesired parts of

harvested fish (organs) back into the ocean (Shester et al. 2011). This practice is

unfavorable to ocean habitats in particular because: by-catch is usually damaged to a

point where it will not survive; and the organic matter being discarded is typically

released in one concentrated location on the ocean floor where it can create a blanket

over the habitat it lands on (Kilpatrick et al. 2011). Both of these scenarios result in

unnecessary organisms’ deaths, affecting the community’s TLs.

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Many organisms that inhabit the ocean floor are photosynthetic (Kilpatric et al.

2011). Photosynthetic organisms cannot survive without access to sunlight, which is

blocked when anything is covering them, such as decomposing organic matter. As

photosynthetic organisms become blanketed by discarded fish waste, they loose their

ability to produce energy and survive. Habitats can become dead zones that cannot

reproduce, cannot oxygenate the water and cannot provide a habitat for organisms.

Studies have documented these areas have decreased oxygen production, community

composition alterations and loss of life (Ban et al. 2014). These issues are all impactful

towards the ocean as a whole, and because the areas are in the deep ocean it is nearly

impossible to remediate them via human conservation. In order to alleviate the ocean of

this habitat destruction, there must be monitoring of these practices to prevent ocean

dumping.

The ocean provides the most habitats on earth due to its size. Poor practices and

climactic changes are damaging these ecosystems in ways that hinder populations to have

healthy carrying capacities, a large diversity of biota, and continuity of habitats spanning

the ocean (Pritcher et al. 2005). Unfortunately as populations decline due to these issues,

their dynamics will dwindle as well, and the possibility of rapid adaption will be less

possible. In order for natural evolution to continue and species diversity to remain, ocean

habitats will need to remain healthy to provide breeding and living grounds to sustain

population dynamics.

4 – Ocean Population Dynamics That Are Being Altered:

The ocean has many layers of species interactions that are increased by its

size. The changes mentioned in previous sections are causing for disruptions of these

population dynamics. For the ocean’s health, it is important to maintain flow of

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nutrients, a strong population biodiversity with genetic variation, and populations with a

carrying capacity that allows for a sustainable existence.

4.1 - Horizontal and Vertical Integration:

All of the oceans combined amasses to ~70% of the earth’s surface. This

area allows for large amounts of species to exist. It is important to consider the three-

dimensionality of the ocean that is not as apparent upon land. Generally organisms on

land, with the exception of birds, have a limited range of area to live in, revolving around

the earth’s surface because of gravity. The ocean adds a dimension, giving organisms the

potential to move both vertically and horizontally. Nutrient distribution becomes less

readily available in the deep ocean as species are more spread out, making this increase

of interactions needed for nutrients to span the food web (Ban et al. 2014).

A factor that interrupts this flow of nutrients is fishing, because it causes a

decrease in populations. With more biomass removed, the progression and amount of

nutrients in the ecosystem is either reduced or stopped (Ban et al. 2014). Elimination of

functional organisms and decreasing the supply of nutrients of a habitat, forces

inhabitance to adapt their diet, migrate to a new location or decrease population size.

Studies have shown, these outcomes, however different organisms have different

vulnerabilities to stressors (Smith et al. 2009). For nutrient flow to be sustained,

organisms will need to go through physiological changes as their environment shifts.

4.2 - Fishing as an Artificial Predator

For populations to remain stable, they must not exceed or go below their carrying

capacity. To ensure that this upper limit is not exceeded, it is important to have predators

to keep populations stable, and to promote competition so that the best-adapted

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organisms reproduce. Introducing fishing to an environment is similar to introducing a

new predator that is not governed by population laws.

A study in the Bay of Biscay used life-history parameters to predict the mass of

fish in a heavily fished area vs. an area that was not fished (Ravard et al. 2014). Figure 4

shows the species that were sampled in this area, and the relative percent difference the

two groups’ mass compared to surveys from other research. Light grey bars represent

fish from areas that were not exploited, while dark grey represents exploited areas.

Difference in body size of organisms in heavily fished habitats compared to untouched habitats:

Figure 4: (Ravard et al. 2014).

The largest decrease in mass of individuals in fished areas occurred in Conger

conger and Merluccius merluccius. These two species are the most commonly fished

organisms in the area. Fishers targeted larger individuals of the populations because it is

easier to capture them, and their size increases economic value. As fewer large

organisms were left in the population, this caused for the only reproductive organisms to

be individuals that have a small body sizes. Targeting and removing larger fish from

populations is likely causing smaller overall populations in fished areas through

removing the larger individuals before they reproduce (Ravard et al. 2014).

The species Dicentrarchus labrax, Merlangius merlangus, Lepidorhombus

whiffiagonis, Scyliorhinus canicula and Dicologlossa cuneata are all R-species (grow fast

with small body sizes and produce several offspring), and are eaten by C. conger and M.

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merliuccius. Both C. conger and M. merluccius are K-species (fewer offspring, larger

overall growth, and longer maturity period). Because R-species do not grow to larger

body sizes, fishers do not target them. In areas that are fished, the R-species increased in

body size (Ravard et al. 2014). There is a strong possibility this change is because with

fewer predators, a larger body size is no longer affecting survival. Areas that are not

fished have R-species with significantly smaller body sizes, helping support this

hypothesis.

The species C. conger and M. meriuccius have a reduction in overall mass in

fished areas, which could mean species are not reaching maturity, and are not

repopulating their environment effectively. Organisms that were not fished in these areas

had their predators removed, which allowed for those populations to increase body size.

This study supports the theory that fishing introduces an uncontrolled predator that alters

the affected organism’s lifecycle, and the organisms that are their prey.

4.3 - Migratory Patterns:

Population migrations are common for ocean species, which changes the biota of

areas annually. Recent issues with these migrations have included destruction of

spawning areas, and fishing organisms during their migration. These impacts have

changed the biota of some ocean communities (Pitcher T, 2005).

The life cycle of migrating fish is to spawn in a location outside of the ocean

(generally fresh water) that is removed from predators, leave that location to nurse, then

move to the ocean to feed and mature, then repeat (Ban et al. 2014). If these spawning

habitats are destroyed, the fish will have no location to spawn, causing an immediate drop

in population size, genetic pool and biodiversity of the community (Catherine et al.

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2002). As these spawning areas are destroyed by human actions, entire generations are

unable to be spawned. These areas are essential for populations to be sustained.

Fishing populations on migratory routes have also caused problems for ocean

communities. Migrations are challenging for species and there are mortalities before

reaching the spawning grounds (Ban et al. 2014). Species have adapted to this migration

and its natural challenges, however the addition of fishing is reducing populations even

more. Reducing populations by an unnatural amount before they can reproduce

decreases the possible amount of offspring (Pitcher T, 2005).

Behavioral changes have also been seen in some fish migratory patterns. In

Norway a group of Atlantic cod was researched to see how their migratory patterns were

altered due to fishing boats (Jørgensen et al. 2008). Fish with migratory routes that made

contact with fishing boasts were seen to shorten the distance they traveled from their

spawning grounds. Other populations that did not have a fishing route in their migration

path did not exhibit changes. It is suggested that in order to increase chances of survival,

migratory paths were decreased to limit interaction with fishing vessels. It is unclear if

this change in behavior is more beneficial to the population, because individuals will not

mature as quickly since there is less food in a smaller migratory route. However not

coming in contact with fishing boats does increase the amount of individuals. Fishing

vessels seem to be impacting migration patterns of ocean organisms.

Migratory ocean species are competing against the fishing industry as their

habitats are destroyed and the quantity of fish that can reproduce is diminished before

they reach spawning grounds. This situation calls for a change in fishing practices and

need for increased research. Spawning sites and migratory patterns should be avoided at

all costs to allow for species to replenish annually. These locations are generally

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concentrated, and thus would not impact the industry dramatically if they were to be

made protected areas. If these areas do not control fishing, it will be challenging to

restore several populations and habitats.

5 – Genetic Shifts Induced by Fishing:

As fisheries continue to act as predators there will be an increase in interspecific

and intraspecific competition for ocean resources, and evolutionary changes will occur

(Uusi et al. 2008). Due increased fishing around the world, there have been different

characteristics that may benefit an individual’s fitness to survive fishing. These genetic

alterations may be positive for individuals, however they do decrease the population’s

gene pool.

5.1 - Fishing Induced Evolution:

Studies have found in several fisheries, fish that have a smaller body size and

reach reproductive maturity faster have higher chances of surviving than individuals with

larger body sizes that reach sexual maturity (Uusi et al. 2008). This genetic manipulation

is likely related to human interference, because naturally faster sexual maturity with a

larger body size are the individuals that reproduce more. Species that show these

changes are 3rd and 4th TL consumers. If fishing was decreased, it is probable larger body

sizes would again become important characteristics for survival.

5.2- Habitat Change Affect on Genetics:

Recently off of New Zealand there has been habitat destruction over the past

several decades. Nearly 70% of the once virgin biomass has been removed from its

habitat. As this change has occurred, researchers have taken samples from Hoplostethus

atlanticus, using gel electrophoresis to test several polymorphic loci’s change in

frequency. It has been seen at the beginning of the study more of the adults were

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heterozygous, while after 15 years the remaining population was primarily homozygous

(Smith et al. 1991). It appears gene pools are being decreased by the removal of

individuals. As well, fewer fish can be spawned in the area because the habitat has been

reduced. These issues are causing problems for ocean organisms’ genetics.

Ocean fisheries have the ability to manipulate the habitats and genetics of the

individuals they breed. It is common practice to take a selected group of brood stock

(mature males) and mate them with one female’s eggs. This greatly reduces genetic

diversity because all offspring are at least 50% genetically identical. Some farms have

documented generations where 55% of the population was genetically identical (Frost et

al. 2006). It is alarming that a large population of fish could have such a similar genome,

and if the habitat were natural, this would not likely occur. The massive decrease in

genetic diversity due to fish farming and contained habitats is beneficial for feeding the

human population. It is likely this change will cause issues for fish survival if enough

genes are lost through these artificial breeding. Another concern is if the nets that these

fish are contained in were to break, an influx of selected bred individuals will be entering

the natural environment, disturbing gene frequencies. In order for gene pools to remain

healthy, fish farms must reduce impacts on natural populations to allow for gene pools to

retain variation.

Natural selection is an important process that should benefit organisms into

becoming a population with a high fitness or result in speciation. This process is ever

changing, as the natural environment is dynamic. Ideally selection would still be natural,

however with the changes humans have been making to environments and fishing

populations directly and indirectly, it is unlikely that population dynamics are

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uninfluenced. These studies suggest that fish are now adapting for human desires instead

of to nature.

6 – Potential Solutions:

Ideally the best solution to these ecological problems would be reducing fishing

so that ocean communities’ interactions could be studied before devastation occurs.

Given our growing population and the increase that fish is taking in feeding our planet, it

is unlikely this will be possible in the near future. Instead new solutions for fish

breeding, and ecosystem management have been put forth and are being used for

commercial business or are still being tested.

Iron fertilization

A recent idea to decrease hypercapnia and ocean acidification is to use iron dust

to spur algal blooms. Iron dust rapidly spurs phytoplankton growth because iron is a

limiting nutrient in the ocean since it does not dissolve well in saline environments.

Phytoplankton is a productive species at sequestering carbon for photosynthesis and

producing oxygen. Removing dissolved CO2 from the ocean will increase the ocean’s pH

to more normal levels, and reduce hypercapnia (Buesseler et al. 2014). Both of these

changes will help ocean habitats and populations recover.

Currently there is not enough data to know what happens to the iron if it is not

absorbed, and the phytoplankton after they die and to the ocean habitat that was living

there (Buesseler et al. 2014). It is likely the phytoplankton will have a ‘boom and bust’

growth because a specific amount of iron is released. This may cause the same issues

that fish waste dumping does if the phytoplankton die and blanket the ocean floor.

However this option should be considered because of its benefits. So far iron fertilization

has only been done in remote areas without much aquatic life. Because this technology is

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new, there have not been definite answers to these questions, however if controlled and

done in a proper location, iron fertilization may be a rapidly productive mechanism.

Aquaponics

Aquaponics is man made habitats suitable for the mass breeding of fish. An

ocean environment is created on land or in nets in a small body of water, for example a

fjord inland of the ocean (Tyson et al. 2004). Nutrients are distributed to the fish, which

are selectively bred or are genetically modified. A large amount of fish can be grown in a

small area.

This practice reduces the amount of space that can be disrupted by fishing vessels

in the ocean, stops the removal of fish from their environment, both of which have many

benefits to ocean communities. Aquaponics does however release large concentrations of

fish waste that could cause a local ecosystem collapse similar to fish dumping. Genetic

diversity of the fish bred is low as few parents are used to produce offspring. The spread

of diseases is rapidly heightened because of the limited space that the fish are given to

live in (Tyson et al. 2004). These issues impact a smaller number of populations and

habitats that using ocean fisheries, and provides food in equal amounts of the ocean.

Each side of aquaponics should be considered, and advancements should be made to the

technology to increase its effectiveness.

Both of these technologies have clear uses that are needed for the ocean to sustain

populations, however it is hard to predict the amplitude of the consequences they may

incur. With increased testing and product development, they should be safe to use and

affective at changing the impacted state of the ocean.

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7 - Conclusion:

Humans have been fortunate to have the ocean as an ecosystem that provides a

wide variety benefits. We are provided with food, transportation, economic potential,

climactic stability and reservoirs for the emissions that we produce. As we look towards

the future, it is important that we maintain a focus on the ocean’s health. Research has

been done on the ocean, however there is more that can be done so that we can use it

without harm.

Compiling several different factors has made it clear that there have been negative

anthropogenic actions affecting several parts of the ocean, from global cycles to allele

frequencies. These changes are not minor, and it is impressive how our society has

become capable of controlling the dynamics of the natural world. It is time to step back

and humble ourselves as a society. A new focus must be instated to explore the

intricacies of our natural environment. It will be important for survival to progress the

knowledge of the ocean as a fishery.

New ideas are spreading to alleviate us of the pending ocean problems such as

aquaponics to reduce pressure on ocean habitats, and iron fertilization to cause

phytoplankton blooms that will consume massive amounts of CO2 in the ocean. These

technologies will likely be implemented as knowledge is increased. The downfalls of

them should be noted from the start.

Therefore, I propose that a focus should be placed on the recovery and

sustainability of ocean habitats. Climate change is already upon us, and it is unlikely

humans will be able to slow its progression because our societies revolve around fossil

fuel use; and as our world continues to heat, more carbon is released from glaciers

creating a positive feedback. Healthy habitats allow for organisms to spawn in a location

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that has several available nutrients and less danger of predators. Having safe breeding

grounds promotes gene pools to increase, biodiversity and populations to grow. It may

be challenging to alleviate ocean acidification and the warming of ocean temperatures,

however if specific habitats like coral reefs and spawning areas can be protected, species

growth will be promoted. With these features, speciation and evolution can occur,

allowing for organisms to adapt to the inevitable change of ocean chemistry. Aquaponics

can be utilized to produce food for the world’s demands, and iron fertilization can be

developed to begin to reduce the amount of carbon in our atmosphere. Habitat protection

will be vital to ensure the survival of species in the oceans being that other variables are

out of control and there is no viable way to stop their progression.

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Acknowledgments:I would like to thank my initial research partners, Nicolas De Castro and Mathew Aitkin

for their help critiquing, strengthening and expanding my knowledge of ocean ecosystems. Dr. Gammon who always made himself available via email or in person to answer questions, provide guidance and improve understanding. Finally I would like to

extend my gratitude to the entire biology, chemistry and physics faculty at Elon University who have germinated my growth in the field of science. I thank you all

whole-heartedly.

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