Bulow, E.S. and Ferdinand, T.J. 2013

08 Fall

The Effect of Consumptive Waste on Mangrove Functionality: A Comparative Analysis

M c G i l l U n i v e r s i t y P a n a m a F i e l d S t u d y S e m e s t e r C e n t r o d e I n c i d e n c i a A m b i e n t a l ( C I A M )

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CIAM

Centro de Incidencia Ambiental

Urb. Los Ángeles, Calle Los Periodistas,

Casa G-14 Planta Alta.

Teléfono: (507) 236-0866 / (507) 236-0868

Tele-fax: (507) 236-0872

Naos Marine Laboratories

Bldg. 356, Amador Causeway, Naos Island

Panama, Rep. de Panamà

McGill University

845 Sherbrooke Street West, Montreal

QC, Canada

H3A 0G4

(514) 398-4455

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Table of Contents

Host Information

Background 5

Contact Information 6

Project Personnel 6

Project Information

Background and Basis 7

The Mangrove 7

Mangroves in Panama 8

Crabs: Mangrove Engineers 11

Mangroves and Salinity 12

The Black Mangrove Ecosystem 13

Waste Management in Panama City 14

Juan Diaz: Study Site #1 15

Punta Chame: Study Site #2 17

The Question 18

Methodology 19

Site Locations 19

Sampling Crabs, Garbage and Trees 19

Sampling and Testing Salinity 20

Results 21

Discussion 25

Limitations and Obstacles Encountered 28

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Looking Forward 28

Logistical Information

Work Log 29

Financial Expenditures 29

Official Recognition Requests 29

Additional Acknowledgments 30

Bibliography 31

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Host Information

Background

CIAM, el Centro de Incidencia Ambiental or the Environmental Advocacy

Center, is a non-profit organization that is dedicated to legally defending the lands, rivers,

oceans and cultural heritages of Panama. Before the creation of CIAM in 2007 Panama

lacked a major environmental group containing activists that initiated legislative

processes. The Board of Directors consists of members independently recognized for

their expertise in their respective fields and their resolute integrity and commitment to

environmental and human rights. Since its creation, the NGO has had enormous

successes in such areas as: climate change, open-pit mining, hydroelectric plants and,

more recently, mangrove and wetland protection.

In all of their endeavors CIAM aims to provide citizens with public information,

promote and facilitate civic participation, advocate sound environmental public policy

and legislate a healthy environment as a human right.

CIAM relies on consensus building across all sectors and scales of society in

order to produce greater influential leverage and construct a productive common vision.

Besides working with individual citizens and communities, CIAM finds partnership in

ANCON, Fundación Almanaque Azul, Sociedad Audubon de Panamá, Fundación

Natura, Fundación Albatros Media, Fundación ProMar, Asociación Oceánica de Panamá

and Fundación MarViva. On an International level CIAM has made alliances with such

groups as the Environmental Law Alliance Worldwide (ELAW), the Inter-American

Association for the Defense of the Environment (AIDA), the Center for International

Environmental Law (CIEL), and Mining Watch, along with major U.S. and Canadian

universities.

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Contact Information

CIAM

Centro de Incidencia Ambiental

Urb. Los Ángeles, Calle Los Periodistas,

Casa G-14 Planta Alta.

Teléfono: (507) 236-0866 / (507) 236-0868

Tele-fax: (507) 236-0872

Correo electrónico: info@ciampanama.org

Project Personnel

McGill University Staff

Tyler Ferdinand (Internship Student)

Email: tyler.ferdinand@mail.mcgill.ca

Telephone: 6585-6552

Ella (Elise) Bulow (Internship Student)

Email: elise.bulow@mail.mcgill.ca

Roberto Ibanez (Internship Supervisor)

Victor Frankel (Internship Teaching

Assistant)

CIAM Staff

Lourdes Lozano

Private Consultant and Internship

Coordinator

Email: lozano.centella@gmail.com

Telephone: 6676-5797

Sonia Montenegro

Deputy Director

Email: smontenegro@ciampanama.org

Telephone: 6675-8021

Tania Arosemena

Director of Legal Affairs

Email: tarosemena@ciampanama.org

Telephone: (507) 6781-4278

Nathalie Vásquez Cabrera

Project Assistant

Email: nvasquez@ciampanama.org

Telephone: 6780-8481

Gustavo Cárdenas

Universidad de Panamá Intern

Email: gustavocardenas507@gmail.com

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Project Information

Background and Basis

The Mangrove

Mangroves are among the most productive and biologically complex ecosystems

on earth, scattering intertidal regions within 30 degrees of the equator (Warne, n.d).

These vital ecosystems are critically important for ecological and social communities

around the world. Mangroves play an important role guarding the low-lying coastal land

by forming a protective barrier which reduces damage caused by storms, limiting wave

energy and preventing the land from being flooded and eroded. This has become much

more globally recognized after the 2004 Asian tsunami that left areas with previously

destroyed mangroves with a much higher rate of casualties and destruction than areas

with intact, healthy mangrove forests (Danielsen et al.2005; Radhika, 2006).

Fig 1 - (http://www.flmnh.ufl.edu)

Their physical presence not only serves as a barrier to protect human populations

but also provides shelter and a food resource for estuarine and coastal fishery food

chains. Many fish, shellfish, birds and other wildlife adopt mangrove ecosystems as

breeding, feeding and nursery habitats. This habitat allows the growth of numerous

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seafood species that make up a significant portion of many countries economies; for

example it contributes $86 million a year to Panama’s economy (Audubon de Panamá,

n.d). Additionally, these wetlands act as an essential filter for hazardous agricultural

effluent as well as urban pollution, safeguarding marine trophic systems.

While these forests have proven to be essential to animals and humans alike, they

have been severely threatened by anthropogenic exploitations. More than 35% of the area

of mangrove forests has been destroyed in the past two decades. This is equivalent to an

annual loss of 3,000 km2 of mangrove forests along shorelines around the world since the

1980’s (EcoLogic, n.d). This alarming loss of mangrove ecosystems plays an important

role in the global climate crisis, as mangroves are one of the most carbon rich of all

tropical forest biomes. Although this particular ecosystem only accounts for 0.7% of all

tropical forests, their

degradation is responsible for

10% of the global carbon

emissions caused by

deforestation. These

ecosystems are among the

most carbon-rich forests in the

tropics not necessarily because

of the tree’s high wood

biomass, but because of the

high organic-rich soils that

account for 49-98% of the

biome’s carbon storage (Fig 2,

Donato et al., 2011).

Mangroves in Panama

Since its geography includes extensive coastlines, Panama has become an

important focus in Central America for mangrove conservation and management. The

topography, climate and varying oceanic conditions across the isthmus gives rise to a

variety of mangrove species on both the Pacific and Caribbean coasts, with the majority

Fig 2 - (Donato et al., 2011)

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of mangroves found on the Pacific perimeter. Out of 172, 000 hectares of mangrove

forest in Panama, around 166,000 hectares are found on the Pacific coast. Of the thirteen

mangrove species present in the Americas, eleven species are native to Panama that fall

under the genera of Laguncularia, Avicennia, Rhizophora, or Pelliciera. The most

common species are the red and white mangroves, Rhizophora mangle y Rhizophora

racemosa respectively. Although the different species may have extremely different

phenotypes, they do share common traits: propagule dispersal by seawater, vivipary, and

their capability to easily adapt. Each mangrove has some form of a salinity filtration

system and a complex root system that allows it to survive in the intertidal zone. Some

have snorkel-like roots called pneumatophores that stick out of the mud to help them take

in air; others use prop roots or buttresses to keep their trunks upright in the soft sediments

at the tide's edge. (Warne, n.d; Betts, 2006).

Although mangroves only account for 5.6% of the total forest cover in Panama,

they are being destroyed at a distressing rate. Between the years of 1980 and 1990

Panama lost 75% of it’s mangrove forests (Ecologic, n,d). Even though some

conservation frameworks have been developed, rampant development continues to

eradicate mangroves from certain regions. Land clearing, aquaculture expansion, over-

harvesting, and private and corporate development are main drivers for mangrove

decline.

In 2003 Panama signed the Ramsar convention declaring the Panama Bay area as

a “wetland of international importance” and in 2005 the bay was declared as a “Site of

Hemispheric Importance” due to its recognition as the most important shorebird site in

Central America. Between one and two million shorebirds of over 30 different species

use Panama during their migration route. For certain bird species, as much as 50% of

their global population depend specifically on Panama Bay for their migration.

(Audubon, n.d).

On top of these significant international recognitions, the Panama Bay Wetlands,

consisting of 80,000 ha, became a National Protected Area in 2009. However, on August

16th

, 2010 Panamanian courts began annulment trials, which ended in the revocation of

the protective law. This impugnment resulted from a dispute over a matter of “prior and

informed consent” inspired by the pressure for urban and resort development (AIDA,

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2011). Under pressure from urban and resort developers, the government suspended this

protected area clause in May 2012 under Article AG-0072. Not only were developers

allowed to take advantage of the protected mangroves, but the Panama’s Aquatic

Resources Authority also reduced the fees for the use of mangroves and the fines for

illegal mangrove clearance, greatly facilitating the destruction of this vital ecosystem.

The fines for illegal cutting of mangroves went from $300,000 per hectare to $40,000 per

hectare, and the fee to get a permit to legally clear cut mangroves went from $150,000

per hectare to $10,000 per hectare (Jackson, 2012). Panama has no large -scale mangrove

reforestation program and these tidal zone trees are difficult to successfully germinate

and replant. At the current state of science and given the cost of the skilled labor required,

$10,000 is not enough to restore a hectare of mangroves. Thus the concept of a developer

replacing trees that are destroyed by construction by planting trees elsewhere becomes

immaterial when corporations discuss their project logistics (Jackson, 2012). Not only

will the continued destruction of the mangroves in Panama release vast amounts of

detrimental carbon into the atmosphere, but will also have drastic deleterious effects on

numerous species that depend on the mangroves for survival. Despite the direct loss of

several at risk mangrove tree species, many globally threatened species like Crocodylus

acutus, Caretta caretta, Tapirus terrestris and Ateles geoffroyi will also be negatively

affected (Audobon, nd).

Something that has seen international attention recently is the severe flooding of

Panama’s main international airport, Tocumen. The Panama Bay mangroves are a major

shield for flooding and extreme weather events like storms and tsunamis by providing a

sink for mass amounts of incoming water. Panama’s major airport has been flooding in

the past years due to the intense destruction of mangroves in Panama Bay, and instead

putting efforts towards restoring the mangroves, the government is building a new airport

further inland.

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Services Goods Qualities

Water Quality Timber Products Biodiversity

Protection against storm surges Ornamental Plants Cultural values

Protection against floods Fish Spiritual values

Retention of nutrients Mollusks and

crustaceans

Ethical values of

conservation

Retention of sediments Other wildlife Values of an alternative use

system

Avenue for aquatic transport Honey Production

Opportunity for recreation Salt production

Opportunity for research

Support of external economies

Stabilization of the

microclimate

Carbon Sequestration

Refuge and nursery for species

with high ecological and

commercial importance

Table 1 – (McHugh, 2007)

Crabs: Mangrove Engineers

There are currently an estimated 275 species of brachyurans associated with

mangrove biomes (Amarasinghe 2009). Of these crabs those of the genus Uca, or fiddler

crabs, are particularly important to the functioning of the mangrove ecosystems. Fiddler

crabs are typically quite abundant in such environments and can be found in densities of

up to 70 crabs/m2 . Fiddlers can be identified most easily by noting the males enlarged

claw which is usually used in social displays and in jousting with rival males. The

carapace and claw of the males are commonly brightly colored depending on the species

while females are less vibrant and possess two claws of smaller, equal size (Hogarth

2007).

The importance of this family of crustaceans to mangrove health emerges from

the crab’s burrowing activity and therefore, the interactions with the soil structure and

composition (Stieglitz, 2000; Wang et al. 2010). The fiddler crab creates burrows to hide

from predators and to take refuge during the higher tides that inundate the mangrove

forests. Burrowing activity alters the topography and micro-hydrology while also

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functioning as a system of channels that carry water, dissolved nutrients and oxygen to

the anaerobic soils around mangrove roots. This bioturbation, the process of changing the

physical, chemical and biological nature of the ecosystem via burrowing, increases the

reactive anaerobic area of the mangrove soils helping to facilitate the decomposition and

mineralization provision of nutrients to improve mangrove viability. The absence of

crabs, and therefore their burrows, could result in plant nutrient deficiencies and

unfavorable soil conditions that would reduce mangrove primary production and damage

the overall ecosystem functionality (Amarasinghe 2009).

Particularly relevant to this study, the presence of crab burrows helps to reduce

soil salinity when, during tidal events, the lining of burrows are flushed and cycled

(Amarasinghe 2009). Although these changes in groundwater and soil composition may

only represent small fluctuations in salinity, without crab burrows a chronic occurrence

of elevated salinity contrary to normal dynamics can hinder not only tree fitness but also

the survivorship of crab populations. In one study conducted in a Kenyan mangrove

ecosystem, two crab species could osmoregulate for a certain period of time in elevated

salinity conditions but could not withstand long-term hypersalinity (Gillikin et al. 2004).

Mangroves and Salinity

The uniqueness of the mangrove is especially evident when discussing its

relationship with the ocean and therefore, an existence in a terrestrially adverse

environment in which vegetation must cope with higher levels of salinity. Mangrove

species are obligated halophytes, growing in habitats with a salinity between that of

freshwater and seawater, seawater being approximately 35 g/l salt (Hogarth 2007,

Suaarez and Medina 2005). Due to these conditions there is generally an osmotic

potential of -2.5 MPa meaning that desalinated water must be taken in against this

pressure (Hogarth 2007). As salinity increases, the ability for the mangrove to counteract

this pressure becomes increasingly difficult. However, evolutionary adaptations to salty

environments have allowed mangroves to thrive along global coastlines.

The main mechanisms of managing salinity are preferential assimilation by roots,

a tolerance of high tissue salt concentrations and elimination of excess salt by secretion

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(Khan and Aziz 2001; Lovelock et al. 2010). The genus Avicennia is capable of

excluding 90-97% of salt at the root surface. Like other halophytes, this is possible by

generating a negative hydrostatic pressure that overcomes the negative osmotic pressure

in the root environment allowing water to be drawn in while excluding potentially

harmful ions (Khan and Aziz 2001, Hogarth 2007). This form of salt exclusion can result

in higher salinity measurements in areas surrounding the root system (Hogarth 2007).

This can become problematic if the available soil is not cycled and redistributed, resulting

in decreased stomatal conductance, lower water potential and accumulation of inorganic

ions (Khan and Aziz 2001).

In some mangrove species, including Avicennia, sodium chloride is deposited in

the bark of stems, roots and also in senescent leaves. When salt deposits accumulate

within the tree’s leaves they are eventually shed, most likely as a method to remove salt

from metabolic tissue (Hogarth 2007). Under chronic salinity stress, leaf mortality is

accompanied by a notable decrease in leaf production rate, which in most cases can lead

to the tree’s death. The ratio of leaf production to leaf death, as well as leaf life span is

extremely important to overall plant fitness due to the leaf surface area being directly

related to the tree’s carbon, nutrient and photosynthetic economy (Suaarez 2005, Sobrado

2000).

Mangrove seedling success is also determined by certain salinity ratios, each

species thriving at a particular salinity ratio (Basak et al. 2004). Avicennia propagules

generally grow best in 50% seawater, but at later stages the optimal salinity is lower (Ball

1988a). This may result in a forest structure in which tree demography is skewed towards

younger individuals when salinity is too high for mature individuals to survive.

The Black Mangrove Ecosystem

The black mangrove, Avicennia germinans, is probably the most widespread

neotropical mangrove. Black mangrove populations are located globally, including the

eastern tropical coasts of North and South America, the Caribbean Islands and parts of

Africa (Houck & Neill, 2009; Ellison et al., 2010). It is generally found at higher tidal

elevations than Rhizophora mangle, the red mangrove, which colonizes the ocean-shore

interface. Black mangroves can only persist where there is adequate protection from

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wave action, and is adapted to sandy, silty clay loam, and muck soils (NRCS, 2005). The

spatial distribution across the intertidal zone for black mangrove, red mangrove and white

mangrove (Laguncularia racemosa) suggests differential flooding tolerance among these

species (Fig 3).

Fig 3 - http://www.dcbiodata.net/explorer/info/habitats

This species is characterized by its opposite leaf pattern and leaves which are

narrow and elliptical in shape, often found encrusted with salt. The root system of

A.germinans consists of long underground cable roots that produce hundreds of thin,

upright pneumatophores that penetrate the soil´s superficial layer to allow root respiration

in anaerobic, waterlogged soils.

On average they grow to around 3-12 m in height, in areas with tidal amplitude

ranges of 2-6 meters (WWF, 2010). It is widely believed that the flowers of Avicennia

germinans are pollinated by insects, principally bees. Reproductive adaptations enable

seedlings to germinate while still attached to the parent tree, a phenomenon known as

cryptovivipary, in which the embryo emerges from the seed coat, but remains in the fruit

before falling from the parent plant. The seedlings, lima bean-shaped propagules, sprout

into 1 inch (2-3 cm), and eventually fall from the parent plant and are able, in the absence

of suitable location, to float for an indefinite period in salt water without rooting.

(FLMNH, n.d)

Waste Management in Panama City

Currently in Panama there is limited legislation in regards to waste management.

Approximately 1,300 tons of garbage is produced daily in the capital city, a number that

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is rapidly rising as the population grows and tourism increases. Public media estimates

that 70% of Panamanian’s waste is collected in urban areas and moved to local dumps to

be burned. The remaining 30% is accumulated in public areas including beaches, forests

and waterways. That is approximately 390 tons of garbage a day that is discarded into

non-managed environmental systems.

In 2010 the national government established the Autoridad de Aseo Urbano y

Domiciliario (AAUD) via Act 51. This institution was designed to take charge of

administering, directing, planning, and developing a waste management framework while

investigating, inspecting and auditing institutions in relation to urban sanitation.

However, after several years there is still the lack of a provision dealing with the

treatment of waste and no prominent education campaigns aimed at redirecting

consumption trends and sparking recycling initiatives (Pereira 2012).

With the existence of the AAUD, the Ministry of Education and Health and the

Autoridad Nacional de Ambiente (ANAM) there is enough political organization to

create legislation but there appears to be no political initiative. A presentation given by

ANAM in 2007 listed problems in regards to waste management ranging from

institutional issues such as the lack of training for the municipal staff to economic issues

such as the lack of availability of loans and investment for the management sector

(Hernandez 2007).

Until the creation of legislation, perhaps fueled by a shift in the cultural paradigm,

garbage will rapidly continue to fill natural niches, negatively affecting ecosystem

functionality and services along with threatening the incredible biodiversity of the

isthmus of Panama.

Juan Diaz: Study Site #1

The Juan Diaz basin, found among the 150 km extent of wetlands that comprises

Panama Bay, has recently received a lot of attention from environmental advocacy

groups. A large portion of Panama Bay, including the bay of Juan Diaz, was part of the

territory declared a Wetland of International Importance in 2003 under the Ramsar

Convention (Ramsar, 2000) and designated a Site of Hemispheric Importance in 2005 as

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the most important shorebird site in Central America (Audubon, n.d). This section was

also part of the protected area that was recently suspended and is now the location of a

series of new construction projects.

The main three developers that spurred the legal challenge to lift the protected

area status are Santa Maria Golf and Country Club, Panama Bay Development and

Compañia Lefevre, the former of which is responsible for a huge portion of mangrove

clearance in the Juan Diaz basin. In the same location Odebrecht has also built a large

water treatment facility to help mitigate Panama City’s water management issues. The

first of three installments will be operational this year, and they are expanding to three

times the current size in the coming years (Fig 4).

Fig 4 – Study Site #1 in the Juan Diaz Basin (Google Maps)

In addition to deforestation, the intact mangrove forest in the Juan Diaz basin is

facing pollution issues stemming from the inefficient waste management system in

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Panama City. Scattered across the forest floor are large amounts of consumptive debris

left behind from fluctuations of the Juan Diaz river level and ocean tides. During the

rainy season, all the street garbage in the local area gets washed into the Juan Diaz river

which discharges into the basin and the mangrove forests.

Punta Chame: Study Site #2

The second black mangrove forest site was located on the northern edge of the

Punta Chame peninsula. This forest also consisted majoritively of the Avicennia

germinans specie however, the surrounding areas also consisted of other species of

mangrove. This forest was not located next to any major industrial enterprises yet was

close to some private homes and tourist hostels. Although there were no direct signs of

such activity in the sampled area, the only notable anthropogenic activity affecting

mangroves within the Punta Chame region is burning for the use of charcoal.

Fig 5 – Study Site #2 in Punta Chame (Google Maps)

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Fig 6 – Map of Both Study Sites (Google Maps)

The Question

This study was created to discover how consumptive waste affects the

bioturbation processes within the mangrove ecosystems and therefore, indirectly, the

health of the mangroves.

The thought process behind the project is as follows:

Fig 7 – Biological Concept

Garbage Crabs Salinity Tree

Fitness

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This simple graphic entails garbage limiting the physical space for crabs to create

burrows. Without the existence of burrows there is limited bioturbation occurring

resulting in an accumulation of salt content and decrease in available nutrients. The

measurement of salinity was used to verify if the waste debris was actually affecting the

crab’s ability to cycle and redistribute soil contents. Salinity was selected as a good

indicator because it also has a very important relationship with the health of the trees.

With elevated salinity ratios there will be consequences for tree functionality and

therefore fitness. We are quantifying fitness, or tree health, through total aboveground

biomass calculated in the quadrats.

With this in mind the resulting question is: Will consumer trash inhibit crab

bioturbation therefore creating higher ratios of salinity which will affect the biomass and

health of the forest?

Methodology

Site Locations

Two site locations were selected for similar climatic conditions and forest

composition, both being in Pacific coast bays and consisting of majoritively Avicennia

germinans. The Juan Diaz location was selected for its condition of being heavily

polluted by consumptive waste, such as plastic and styrofoam debris. The Punta Chame

location was selected for its condition of being pristine and garbage free.

Sampling Crabs, Garbage and Trees

At both locations a 4 transect by 5 quadrat sampling design was utilized, transects

being spaced 10 meters apart and quadrats being spaced 10 meters apart along those

transects. Quadrats were 1 m2. Within quadrats the number of crab holes and percent

garbage cover were calculated. Percent garbage cover was calculated by laying a 1 m2

piece of plastic fencing with 127 holes over the quadrat and counting how many holes

contained garbage. This was converted in percentages by dividing the number of garbage

containing holes by 127 and multiplying it by 100. Note that the Punta Chame location

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was selected due to its garbage free condition and therefore garbage cover was always

zero percent. From the center of each quadrat a 2.5 meter radius was used to incorporate

all surrounding trees. The circumference at breast height of each tree within the 2.5-meter

radius was measured and later converted to diameter at breast height (DBH). Many

researchers have used the following formulas to calculate biomass based on the work

done by Fromard et al. (1998):

If 1<dbh<4 (cm); then y = 200.4*DBH^2.1 (g)

dbh> 4 (cm); then y = b(DBH)^a; where a = 2.4 and b = 0.14 (kg)

Sampling and Testing Salinity

In every quadrat a soil sample was taken. This was done by inserting a spade in a

randomized spot within the quadrat until it reached a depth of 10 cm. Soil was then

collected from the bottom of the remaining hole and stored in ziplock bags to be later

tested in the lab.

Testing of the soil samples followed procedures outlined by the Salt Action

initiative of the government of New South Wales (NSW). Soil samples were left to dry in

open containers in room temperature (~27 C) for a period of 2 days. In the lab dried

samples were crushed to eliminate any large aggregates. Five grams of each soil sample

were separately weighed and combined with 25 ml of distilled water in glass beakers.

Each soil solution was mixed until any noticeable clumps were dissolved and allowed to

settle for at least two minutes. The top layer liquid was then transferred to a separate

beaker where an OysterTM Portable pH/Conductivity/TDS/ORP Salinity kit

conductometer (accuracy +/- 2%FS) was used to measure the salinities of the solutions

by placing the meter electrodes directly into the solution. Readings were recorded and

equipment was washed with distilled water before proceeding to the next sample. Once

all samples were measured the salinity meter readings were converted to soil salinity

(ECe) by multiplying the value by the conversion factor based on the texture of the soil

sample (Table 2).

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Conversion Factors

Soil Texture Multiplication Factor

Sands 17

Sandy Loams 13.8

Loams 9.5

Clay Loams and Light Clays 8.6

Medium and Heavy Clays 7

Table 2 – Soil Conversion Factors

Results

Table 3 – Qualitative Observations

Salinity

A two-tailed t-test revealed a significant difference in the soil salinity at Juan Diaz

and at Punta Chame. Average soil salinity in Juan Díaz was 42.8 ppt while Punta Chame

had an average soil salinity of 33.8 ppt. (Figure 8, two-tailed t-test, t=2.024, df=38,

p=0.024). There is also a significant linear relationship between soil salinity and percent

garbage cover in the Juan Diaz forest (Figure 9, n = 20, R² = 0.31, P = 0.013).

Juan Díaz Punta Chame

Large amounts of leaf litter Small amounts of leaf litter

Limited Branching Complex branching

Weak, dry branches Strong, thick branches

Drier soil Moist soil

Low density of seedlings Medium density of seedlings

Some birds Birds, lizards, insects

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Crab Holes

A two-tailed t-test revealed a significant difference between the number of crab

holes in Punta Chame and Juan Díaz yielding an average of 147 and 6.5 holes per quadrat

respectively (Figure 10, t = 2.024, df=38, P < 0.0001). Punta Chame had a total of 2944

crab holes within its 20 quadrats, while Juan Diaz had 130 crab holes in total.

Additionally, the number of crab holes decreases linearly with increasing percent garbage

cover in the Juan Diaz forest (Fig 11, n=20, R² = 0.33, P<0.008).

10

20

30

40

50

60

70

80

Soil

Sal

init

y (

ppt)

Punta Chame Juan Diaz

A Comparasin of Soil Salinity (ppt)

Across both Sites

Fig 8 - Soil salinity levels in parts per

thousand (ppt) from two black mangrove

forests, n=20 in each site, measured with

an Osyter conductivity meter. (t = 2.024, df=38, P=0.024)

0

10

20

30

40

50

60

70

80

0 10 20 30 40 50

Soil

Sal

init

y (

ppt)

Percent Garbage Cover (%)

Soil Salinity (ppt) vs Percent Garbage

Cover in Juan Diaz

Fig 9 - Soil salinity levels (ppt) as a function of

percent garbage cover in the Juan Diaz black

mangrove forest, n=20, measured with an Osyter

conductivity meter. (R²=0.31, P=0.013)

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Biomass

The amount of trees within the radii of the quadrats in Punta Chame numbered 53 alive

and 1 dead. In Juan Díaz there were 159 alive and 212 dead. Within the quadrats, Punta

Chame had a total biomass of 159.194 kg while Juan Díaz had a total of 38.093 kg.

0

50

100

150

200

250

300

# C

rab H

ole

s

Punta Chame Juan Diaz

Number of Crab Holes per Quadrat

0

2

4

6

8

10

12

14

0 10 20 30 40 50

Num

ber

of

Cra

b H

ole

s p

er Q

uad

rat

Percent Garbage Cover (%)

Relationship between percent garbage

cover and number of crab holes per

quadrat in Juan Diaz

Fig 10 - Number of crab holes per quadrat in two

black mangrove forests n=20 in each location,

(t=2.024, df=38, P < 0.0001)

Fig 11 - Number of crab holes per quadrat as a

function of percent garbage cover in a black

mangrove forest, n=20, (R² = 0.33, P < 0.008)

24 | P a g e

53

159

1

212

0

50

100

150

200

250

Punta Chame Juan Diaz

Num

ber

of

Indiv

idual

s

Number of Individuals

Species Density

Dead Trees

159 194

38 093

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

Punta Chame Juan Diaz

Bio

mas

s (k

g)

Location

Total Biomass (kg)

Fig 13 - Total number of individual black

mangrove trees ± SD in both locations. Blue

represents alive trees and red represents dead

trees

Fig 12 - Total above ground biomass (kg) ± SD measured

in 20^2 in Punta Chame and Juan Diaz black mangrove

forests.

Number of Individuals

Dead Trees

25 | P a g e

Discussion

Simple qualitative observations indicate that Juan Diaz, in comparison to Punta

Chame, is in a degraded state. While the ground cover in Punta Chame mostly consisted

of moist soil, crab activity, sapling growth and minimal leaf litter, the Juan Díaz forest

was composed of garbage, large amounts of leaf litter and dead tree matter. Although this

study does not explicitly prove that the rampant quantity of trash is the main cause of the

degraded condition of the Juan Diaz’s, it does suggest that there is a quantifiable

difference between the two forests despite their abiotic and biotic similarities. These

results support our initial model where garbage decreases crab burrowing capabilities

leading to a change in soil quality that in turn affects the health of the mangrove (Fig 7).

There was a significant difference between the number of crab holes per quadrat

in both forests (P < 0.0001) suggesting that less soil was subject to bioturbation processes

(Fig 10). As mentioned earlier, a lack of bioturbation processes reduces the provision of

nutrients to improve mangrove viability and may also promote the accumulation of

harmful proportions of certain soil compounds. Literature suggests that a large absence of

crabs could result in plant nutrient deficiencies and unfavorable soil conditions that

would reduce mangrove primary production and damage the overall ecosystem

functionality (Amarasinghe 2009).

Our results also yielded a significant difference between forests in terms of soil

salinity (P = 0.024) potentially indicating a lower soil quality in Juan Diaz (Fig 8 ).

Another aspect keeping the level of salinity high, could be in part due to the fact that one

of the main mechanisms of managing salinity is excess salt secretion by roots (Khazn and

26 | P a g e

Aziz 2001; Lovelock et al. 2010) Due to the large amount of garbage in the Juan Diaz

forest, salt secreted by roots and pneumatophores may be accumulating in the

surrounding soil since garbage could be inhibiting tidal flushing. In Avicennia, sodium

chloride is also deposited in senescent leaves, and when accumulated, the tree’s leaves

eventually shed, most likely as a method to remove salt from metabolic tissue (Hogarth

2007). Therefore, if the roots cannot successfully excrete the salt, then the leaves must

regulate salinity levels. Previous studies show that under chronic salinity stress, leaf

mortality is accompanied by a notable decrease in leaf production rate, which in most

cases can lead to the tree’s death. Our data and recorded observations coincide very well

with the literature as we observed a high quantity of leaves on the forest floor and many

dead trees indicating that it is quite possible that higher salinity levels are in part

responsible for the forest’s degradation.

Contrary to the original hypothesis, salinity was lower in areas with higher

garabage cover. The initial thought process behind this hypothesis was that garbage

would inhibit crabs from being able to cycle salt within the soil. However, based on the

results it may be the case that salt is settling on garbage and leaf litter instead of on the

superficial layer of the soil. This being said, the average salinity being higher in Juan

Diaz rather than Punta Chame could still be explained by a limited amount of

bioturbation. Although salt may be settling on garbage and leaf litter, the salt being

excreted or excluded from the mangroves may be accumulating around the root systems

due to the lack of bioturbation. Therefore, this study still demonstrates a negative impact

of elevated salinity levels.

27 | P a g e

One way we have come to this conclusion is based on the forest composition and

biomass. Not only was there a large reduction in biomass in Juan Diaz despite the much

higher number of individuals, but there were more dead trees present than alive trees,

inferring a damaged ecosystem (Figure 13).

Our results reveal a significant difference between Juan Diaz and Punta Chame in

terms of their crab populations and their soil salinity levels giving rise to a large

difference in biomass and tree composition. The presence of garbage could be

influencing the deterioration of the Juan Diaz black mangrove forest, since it significantly

influenced the salinity (p = 0.013) and number of crab holes (p < 0.008). It is hard to

know exactly what factors are influencing mangrove health and to what magnitude. There

are numerous indicators of health that this study could have utilized which could have

potentially offered different results. With this realization it is recommended that more

studies are designed to identify the key sources of degradation and their importance.

Despite the degradation of the Juan Díaz mangroves, conservation action may

reverse existing degradation trends. This study was not only designed to bring insight to

mangrove dynamics but was also carried out to encourage political action towards

mangrove preservation and environmentalism. This study suggests that Panama needs a

more effective waste management system to keep consumptive waste out of natural

systems. This may entail the formation of new legislation but may also require a shift in

the Panamanian cultural paradigm in which the common citizen is more conscious of

daily consumption habits.

28 | P a g e

Limitations and Obstacles Encountered

Throughout the course of our internship and research project we encountered

several obstacles and limiting factors. Of all of these the three that were the most

impacting were transport, contacts and funding. Transport was extremely difficult

considering the amount of equipment that we needed to transfer to our study sites. With

the lack of a personal vehicle, much time, effort and money was spent carrying pounds of

equipment via public transportation in crowded conditions. Access to both of our study

sites were also very difficult to get to in general and always dependent on other people.

These study site contacts were difficult to find, maintain and utilize. Access to Juan Diaz

was granted by a stroke of good fortune while access to a control site took almost two

months of contact searching, communicating and planning. Finally, funding may have

been the greatest obstacle and limitation. This is due to the fact that the original study

included measuring nitrogen soil content rather than salinity. Almost $400 was spent to

design an experiment that looked at nitrogen on a temporal scale. However, after the

necessary chemicals ran out, additional expenses were deemed too costly to purchase the

remaining chemicals needed to complete the experiment. Therefore, the original

equipment purchased had no final value and approximately 2 months of work was

nullified.

Additional minor obstacles included:

-Access to technical expertise

-Time constraints when balancing course load and contact availability

-Manpower

29 | P a g e

Looking Forward

The main objective of supplying this study to the Centro de Incidencia Ambiental

was to add to an index of citable knowledge in hopes that they will be able to utilize it in

some shape or form when suggesting conservation legislation or educating the greater

public. Additionally, the research team would like to see this study encourage additional

and similar investigations that may in the long run contribute to sparking political

initiatives that will aid in formulating environmental policy and frameworks. Research,

like the type conducted in this project, will help to elucidate biological details that in turn

will support effective environmentalism.

Logistical Information

Work Log

Throughout our internship approximately 35 days were dedicated to work either in the

CIAM office, performing literature review and research or attending CIAM coordinated

events. Additionally, 7 full days were spent in the field.

Financial Expenditures

Hardware 352.43

Taxis ~$58

Bus ~$40

Lodging $30

Total $480.43

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Table 4 - Expenses

Official Recognition Requests

Official acknowledgement letters should be sent to the following individuals:

1. Lourdes Lozano

2. Tania Arosemena

3. Natty Vasquez

4. Rodrigo Noriega

5. Sonia Montenegro

6. Gustavo Cárdenas

The above six individuals can have their letter addressed to:

Urb. Los Ángeles, Calle Los Periodistas

Casa G-14 Planta Alta.

Panamá, Rep. de Panamá

Additionally:

7. Ivania Cerno

Naos Marine Laboratories

Bldg. 356, Amador Causeway, Naos Island

Panama, Rep. de Panamà

8. Carlos Manuel Peralta

cmperalta@odebrecht.com

Additional Acknowledgments

We would like to thank:

Rose Marie and Gilles for their hospitality and guidance.

César Rodríguez for his assitance in Punta Chame.

Elana Evans and Samuel Bulow for their assitance in Juan Diaz.

Catherine Lovelock for all the information she provided.

31 | P a g e

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