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The increasing urbanization of much of the world’s coasts threatens irreversible damages to beach ecosystems, if unchecked. Unfortunately, beach monitoring programmes for remediation actions are uncommon, especially for less developed nationswhere infrastructural development and socio-economic goals are regarded more important than environmental goals. This study aimed at obtaining information about the effects of themodification and use of beaches and dunes on beach biota using ghost crab burrow density and size as variables. The study tested a hypothesis that themean densities and sizes of ghost crab burrows on six beaches under three categories of human use in the Central Region of Ghana are different. Results indicated that low use beaches had significantly higher numbers of burrows and larger burrow sizes compared tomediumuse and high use beaches. Since physical and environmental parameters were consistently the same amongst the six surveyed beaches, the paper concluded that the differences in the observed beach use and dune modifications were responsible for the observed differences in ghost crab abundance and sizes. Major beach use such as intense trampling levels and clearing of dune vegetation for infrastructural developments are most likely responsible for the observed differences. On account of ecological considerations, it is recommended that beach land use reforms by coastalmunicipal authorities inGhana should ensure that infrastructure development along undeveloped sections of the coast is limited to a safe distance from the shoreline. There should also be consideration of natural vegetation barriers between development and the beach to enhance natural beach–dune ecosystem interaction.
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Regional Studies in Marine Science 2 (2015) 87–94
Contents lists available at ScienceDirect
Regional Studies in Marine Science
journal homepage: www.elsevier.com/locate/rsma
Human use and modification of beaches and dunes are linked to ghost
crab (Ocypode spp) population decline in Ghana
F.E. Jonah a,, D.W. Aheto a, D. Adjei-Boateng b, N.W. Agbo b, I. Boateng c, M.J. Shimba d
aDepartment of Fisheries and Aquatic Sciences, University of Cape Coast, Cape Coast, Ghana
bDepartment of Fisheries and Watershed Management, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
cSchool of Civil Engineering & Surveying, University of Portsmouth, Portsmouth, UK
dDepartment of Natural Sciences, Sebastian Kolowa Memorial University, Department of Natural sciences, Tanzania
highlights
The study assessed the response of ghost crabs to human stressors.
Beaches were categorized into high use, medium use and low use beaches.
Burrow sizes and densities were significantly higher at the low use beaches.
Several human uses are attributed to low crab numbers recorded on impacted beaches.
There is the need to pursue direct ecological beach management policy in Ghana.
article info
Article history:
Received 20 May 2015
Received in revised form
12 August 2015
Accepted 19 August 2015
Available online 21 August 2015
Keywords:
Human impacts
Beach management
Beach ecology
Ghost crab populations
Ghana
abstract
The increasing urbanization of much of the world’s coasts threatens irreversible damages to beach
ecosystems, if unchecked. Unfortunately, beach monitoring programmes for remediation actions are
uncommon, especially for less developed nations where infrastructural development and socio-economic
goals are regarded more important than environmental goals. This study aimed at obtaining information
about the effects of the modification and use of beaches and dunes on beach biota using ghost crab burrow
density and size as variables. The study tested a hypothesis that the mean densities and sizes of ghost crab
burrows on six beaches under three categories of human use in the Central Region of Ghana are different.
Results indicated that low use beaches had significantly higher numbers of burrows and larger burrow
sizes compared to medium use and high use beaches. Since physical and environmental parameters were
consistently the same amongst the six surveyed beaches, the paper concluded that the differences in the
observed beach use and dune modifications were responsible for the observed differences in ghost crab
abundance and sizes. Major beach use such as intense trampling levels and clearing of dune vegetation
for infrastructural developments are most likely responsible for the observed differences. On account of
ecological considerations, it is recommended that beach land use reforms by coastal municipal authorities
in Ghana should ensure that infrastructure development along undeveloped sections of the coast is limited
to a safe distance from the shoreline. There should also be consideration of natural vegetation barriers
between development and the beach to enhance natural beach–dune ecosystem interaction.
©2015 Elsevier B.V. All rights reserved.
1. Introduction
Beaches and associated dunes serve as essential habitats for
plants and invertebrates, as well as feeding and nesting sites for
birds and sea turtles (Baird and Dann, 2003;Lastra et al.,2010).
Corresponding author.
E-mail address: fredrick.jonah@ucc.edu.gh (F.E. Jonah).
Beaches are well sought after by people for recreational, tourism
and residential purposes (Klein et al.,2004;Noriega et al.,2012).
These multiple competing uses have contributed to the ever-
increasing human pressure on beaches and dunes especially for
recreational access and development of coastal lands (Defeo et al.,
2009). Indeed, the degradation of beaches has been a matter of
global concern in recent years (Ramsay and Cooper, 2002). It is
confirmed that over 70% of the world’s beaches are experiencing
coastline retreat because of coastal erosion, largely due to human-
http://dx.doi.org/10.1016/j.rsma.2015.08.013
2352-4855/©2015 Elsevier B.V. All rights reserved.
88 F.E. Jonah et al. / Regional Studies in Marine Science 2 (2015) 87–94
induced impacts (Bird,1985;Anthony,2005). The competing mul-
tiplicity of demand for beach and dune resources has severely mod-
ified them around the world (Nordstrom,2000;Coombes et al.,
2008). Indeed, beaches are not just piles of sand; they support a
wide range of biodiversity that play key ecological roles and hence
require conservation and management.
All the world over, limited management interest have been
traditionally directed towards ecological damage of beaches and
dunes caused by human development and over-exploitation of
sandy coastlines (Nordstrom et al.,2000;Noriega et al.,2012).
However, more attention has been given to shoreline stabiliza-
tion, erosion management and maintaining the aesthetic appeal
of beaches over the years (Schlacher et al., 2008). Environmen-
tal monitoring and assessments of sandy beach ecosystems is rare
across the globe despite the great social, economic and environ-
mental importance of sandy shores (Lucrezi et al.,2009a,b). The
effects of the massive trampling that metropolitan beaches may
endure either seasonally or year-round remain largely unexam-
ined (James, 2000). Poor management of coastal ecology is even
more evident along the coastlines of developing nations, where
there are often trade-offs between development goals and environ-
mental protection. However, development and implementation of
monitoring programmes on coastal systems may aid in the timely
detection and remedy of possible irreversible ecological damages
resulting from human use of beaches and dunes.
Ghost crabs (Fam. Ocypodidae, Gen. Ocypode), are one of the
most efficient biological indicators used to monitor human dis-
turbances on sandy beaches (Barros,2001;Lucrezi et al.,2009a,b;
Aheto et al.,2011). It has been applied to measure the effects of
various human disturbances on sandy beach ecology, including
off-road vehicles (Blankensteyn,2006;Moss and McPhee, 2006;
Schlacher et al.,2007), shore armouring (Barros,2001;Aheto et al.,
2011), beach nourishment and bulldozing (Peterson et al., 2000),
tourism (Schlacher et al., 2011) and urbanization (Noriega et al.,
2012). In these studies, ghost crabs densities were reported to be
lower at human affected areas. Most coastal ecologists have ac-
cepted ghost crabs as useful biological indicators because they oc-
cur at both unvegetated beach and dunes (Noriega et al., 2012) and
they are the top invertebrate predator living on beaches (Barrass,
1963;Schlacher et al.,2007). Changes in their density and popu-
lation structure are also easy to estimate by counting and measur-
ing the burrow openings (Barros,2001;Schlacher et al.,2007) and
indeed, they are widespread and abundant on tropical to warm-
temperate beaches (Quijon et al.,2001;Noriega et al.,2012).
This paper uses ghost crabs as bio-indicators to estimate beach
health conditions. This approach is often perceived by coastal
authorities in developing countries as expensive due to the labour-
intensive nature of estimating beach biodiversity. However, recent
studies such as Aheto et al. (2011) and Jonah et al. (2015b)
have established this technique to be inexpensive, simple to
undertake and easily funded by coastal authorities in developing
nations taking cognisance of the useful ecological benefits of such
programmes.
In Ghana, beaches of the Central Region are the most sought-
after for tourism purpose, with a combination of other human
stressors leading to severe transformations of beach and dune
systems. Beach ecological studies are particularly important in
the context of sea level rise resulting from climate change and
poor land use in coastal areas of the country (Adotey et al.,
in press). Other human pressures include urbanization in the
active coastal strip, sand mining on commercial scale, destruction
of beach vegetation, fishing activities, waste disposal and beach
nourishment. Unfortunately, the environmental impacts of these
activities have received little considerations in the past (Armah,
1991;Appeaning-Addo,2009). This makes it essential to conduct
studies on these beaches to gauge the ecological change resulting
from these multiple human use and stressors to inform beach
management decisions at the municipal and national levels.
During the past 40 years, beaches near Cape Coast in the Cen-
tral Region of Ghana have undergone significant changes due to
increased human activities within the active coastal zone (Jonah,
2015;Adotey et al.,in press). In recent years, there has been an
increasing demand for coastal lands for tourism activities, with
infrastructure constructed on land previously occupied by dune
vegetation. Beach sand mining is also widely practised on most
sandy beaches at varying scales, to feed the local construction in-
dustry (Mensah,1997;Jonah et al.,2015a). These have contributed
to accelerated beach and dune erosion, making facilities along the
zone vulnerable to sea waves. In response, the central government
has constructed a 1.5 km rock revetment sea defence and sev-
eral gabions to protect communities and road infrastructure, whilst
property owners have also undertaken several small-scale projects
to protect their investments. In addition, most beaches show signs
of human impacts including campfires, trampling, litter and ‘bush
toilets’.
The objective of this paper is to contribute to existing knowl-
edge on the ecological conditions, habitat properties and human
use of selected beaches in the Central Region of Ghana using Ghost
crab burrow densities and size variations, intensity of beach tram-
pling and other physical environmental conditions such as sedi-
ment temperatures as primary data sources.
2. Materials and methods
2.1. Study sites
This study was conducted on beaches in the mid-portion of the
Central Region coast of Ghana from October 2013 to February 2014.
Study sites were selected based on field observations made by
Jonah (2014) and preliminary field surveys carried out in October
2012. Six beach sites were selected based on level of human
activities (Figs. 1 and 2). The selected sites were qualitatively
classified as ‘low use’, ‘medium use’ and ‘high use’ based on
levels of human disturbances (Table 1). Two sites (Saltpond I and
Saltpond II) located on the same beach stretch in the Mfantseman
District and southeast of the town of Saltpond were selected as the
‘low use’ beaches. These two sites were 1 km apart, situated about
2 km from the nearest community in Saltpond, and receive very
low levels of visitors. The term ‘medium use’ was associated with
beaches that support moderate levels of trampling, sand mining
and infrastructure development. The term ‘high use’ was used for
beaches that support small to medium scale beach sand mining
activities, high levels of trampling, cleared dune vegetation and
high levels of infrastructure development on the adjoining dune
(Table 1).
2.2. Data collection
Two species of ghost crabs, Ocypode cursor and Ocypode africana,
are found on sandy beaches in Ghana (Aheto et al., 2011). This study
assessed the differences in densities and sizes of the ghost crabs
burrows across the six selected beaches. In addition, some physical
environmental parameters that affect ghost crabs distribution
were measured. Surveys were done at approximately the same
tidal period using standard tide tables from the Ghana Ports
and Harbours Authority (GHAPOHA, 2013). During each survey
period, all surveys took place very early in the morning to ensure
consistency and minimize variation in environmental conditions.
Early morning sampling helps to reduce and eliminate the effect
of overlooking burrow openings due to ghost crabs plugging the
openings during the heat of the day (Lucrezi et al.,2009b;Moss
and McPhee, 2006).
F.E. Jonah et al. / Regional Studies in Marine Science 2 (2015) 87–94 89
Fig. 1. Map showing surveyed beaches in the Central Region of Ghana.
Fig. 2. Aerial photographs of surveyed beaches in the Central Region of Ghana.
Estimates of the population density of ghost crabs were
achieved by counting the number of burrow openings occurring
within 1 m2quadrats (Aheto et al., 2011). This follows the assump-
tion that the presence of a burrow on the beach corresponds to the
presence of the crab (Wolcott, 1978). Burrows need to be main-
tained daily or they collapse, thus it is reasonable to assume that
the presence of a burrow corresponds to the presence of a ghost
crab (Valero-Pacheco et al.,2007;Noriega et al.,2012) and there-
fore useful in estimating the number of crabs present on particular
beaches. Preliminary surveys identified that the intertidal zone of
all the surveyed beaches varied between 17 and 31 m, depending
on tidal conditions, with about 20–25 m of the beach berm inhab-
ited by ghost crabs on the individual beaches. On each beach, five
replicate samples were taken along three line transects oriented
perpendicular to the direction of the shoreline at 50 m intervals.
Surveys on each transect was initiated by casting quadrats at 1–2 m
above the low water mark line. On each transect, five different sam-
pling using quadrats of 1 m2dimension was done at 4.5 m line
interval. Burrow diameters were also measured using a vernier cal-
liper within quadrats to estimate sizes (carapace length) of crabs.
This methodology follows the findings of Strachan et al. (1999) and
Tureli et al. (2009), that there is a strong positive correlation be-
tween carapace length of ghost crab and burrow diameter. Diam-
eters of all encountered burrows within all quadrats were taken
during three surveys.
Additional data on physical environmental conditions includ-
ing sediment and air temperatures were taken and analysed as
key environmental and habitat metric of the beaches. Sediment
90 F.E. Jonah et al. / Regional Studies in Marine Science 2 (2015) 87–94
Table 1
Summary of classification of human uses and habitat parameters of surveyed beaches.
Parameter High use Medium use Low use
Castle Philip Quaicoe Ola Moree Saltpond I Saltpond II
Latitude 5°611.80′′N 5°611.15′′ N 5°559.61′′ N 5°819.38′′ N 5°122.77′′ N 5°124.20′′ N
Longitude 1°1434.08′′W 1°1437.97′′ W 1°1723.81′′ W 1°1130.66′′ W 1°146.75′′ W 1°117.75′′ W
Manual beach cleaning Weekly Daily–weekly Monthly Occasional Never Never
Dune vegetation Cleared Moderately
modified
Strongly
modified/cleared
Cleared Intact Intact
Trampling Very high Moderate to high Moderate Moderate Very low Very low
Sand mining Small to medium scale
commercial
Small to medium
scale
Small scale Small to large
scale
None None
Sea defence (seawall, wire
mesh revetment)
Present Present Absent Absent Absent Absent
Infrastructure
development
High High Moderate Low None None
All-terrain vehicle (ATV)
use
Yes No No No No No
Scarp height, m (S.E) 0.682 (0.14657) 0.256 (0.10595) 1.096 (0.07916) 0.874 (0.05026) 0.048 (0.02396) 0.056 (0.02731)
Mean grain size, µm (S.E) 0.5783 (0.03186) 0.5783 (0.02909) 0.4783 (0.03624) 0.7117
(0.05871)
0.4783
(0.02519)
0.4783 (0.02693)
Mean beach users per
30 min (n=8)
79.38 28.38 10.38 26.25 1.5 0.75
samplings were done using sediment corers (15 mm diameter,
300 mm deep) to collect samples to a depth of 200 mm from
the five quadrats. Five replicate sediment cores were taken within
each quadrat and analysed separately to obtain the variability in
grain sizes across the entire beach. Sediment cores were used
wholly to ensure that the variability in sediment sizes up to a
depth of 200 mm was captured. Samples were analysed using the
‘sieve method’. In the laboratory, sediment granulometry was de-
termined by dry-sieving samples through a nested series of nine
sieves arranged in decreasing order of mesh aperture (4750, 2000,
1000, 710, 600, 425, 300, 200, 75 µm). The heights of beach scarps
were also measured once during the study at 20 m intervals over a
distance of 200 m on each beach. Scarp heights have been identi-
fied as being the consequence of human use of beaches and dunes
(Mensah,1997;Esteves et al.,2002). Sand and air temperatures
were taken at all the beaches during each survey using a mer-
cury thermometer. Sediment temperature were taken at a depth
of 200 mm. Wave period for each beach was also determined by
counting the number of waves breaking in the surf zone during a
3-min period. In addition to these, the number of beach users was
recorded over 30 min time interval, on each Saturday afternoon
before Sunday morning ghost crab surveys and used as a proxy to
human trampling. This procedure was achieved with the assistance
of enumerators placed concurrently on each beach.
2.3. Data analysis
A one-way analysis of variance, followed by a post hoc Bonfer-
roni’s test was used to compare burrow densities and diameters
among sites. Mean sediment grain was calculated with the GRADI-
STAT software, using the Folk and Ward method (Blott and Pye,
2001). Spearman’s rank correlation was used to assess the rela-
tionships between physical and environmental factors and burrow
density of ghost crabs.
3. Results
3.1. Environmental conditions, habitat properties and human use
Wave periodicity was relatively constant at all sites with values
ranging from 5.1 to 5.3/min. All six surveyed beaches had medium
energy waves with an average height of 1 m breaking in the surf
zone (GHAPOHA, 2013). Mean scarp heights ranged from 0.048 m
at Saltpond I to 1.096 m at Ola (Table 1). The weather conditions
that prevailed during the study period were mostly warm and
dry. Sediment temperature ranged from 25°to 39 °C during
surveys, but did not vary significantly among sites (ANOVA, p>
0.05). Sediment temperature was positively correlated with air
temperature (Pearson’s r=0.716,p<0.0001). Air temperature
at the time of survey (0500–0800) ranged from 24°to 33 °C. Sand
from all sites fell in the medium sand category and ranged from a
mean grain size of 0.4783 µm at three sites (Ola, Saltpond I and
Saltpond II) to 0.7117 µm at Moree. Sediment grain sizes did not
vary significantly among the six beaches (ANOVA, p>0.01).
Data pooled for all sites showed no correlation between
sediment grain size and ghost crab burrow density (Spearman’s
ρ, r= −0.741,p=0.092). Erosion scarp height was found
not to have an effect on burrow density at all sites (Spearman’s
ρ, r= −0.429,p=0.397). The number of beach users varied
significantly amongst the categories of beaches (ANOVA, F5,42 =
16.65,p<0.0001).
3.2. Burrow density and size variation
Nine hundred and sixty (960) quadrats were surveyed during
this study. O. africana and O. cursor were observed to co-habit
at all surveyed beaches (Fig. 3). Ghost crabs were observed to
occur 1–3 m from the low water line, across the beach into the
dune vegetation. Mean burrow density was highest at the low
use beaches, with values of 44 m2±5.05 burrow m2and
38 ±5.35 burrow m2for Saltpond II and Saltpond I respectively,
followed by the medium use and high use beaches (Table 2).
Mean burrows densities were found to be significantly differ-
ent between sites (Table 3). Mean burrow densities were signif-
icantly higher at low use beaches (Saltpond I and Saltpond II)
compared with medium use beaches (Ola and Moree) and high
use beaches (Castle and Philip Quaicoe) (Bonferroni, p<0.0001).
No significant differences were found between burrow densities
at the medium use and high use beaches (Bonferroni, p>0.01),
though recorded burrow density means were slightly higher at the
medium use beaches. The highest monthly ghost crab abundance
occurred at Saltpond II (56.53 ±13.01 burrow m2, mean ±S.E)
in February, whereas the lowest monthly abundance was recorded
in Moree (7.56 ±2.48 burrow m2, mean ±S.E) also in February
(Fig. 4).
Mean diameters of burrows differed significantly among sites
(ANOVA, Table 4). Mean ghost crab burrow diameters were also
significantly higher at the low-used beaches compared to mean
F.E. Jonah et al. / Regional Studies in Marine Science 2 (2015) 87–94 91
Fig. 3. Ghost crab species found in Ghana: (A) O. cursor and (B) O. africana. (Photos by F.E. Jonah.)
Table 2
Summary of mean burrow densities and mean burrow diameters at six sites with standard error.
Castle Philip Quaicoe Ola Moree Saltpond I Saltpond II
Mean burrow density (±S.E) 14.48 17 19 18.38 38 44
(1.80) (1.98) (2.34) (2.59) (5.35) (5.05)
Burrow diameter means (±S.E) 6.23 8.43 9.28 10.09 19 20.8
(0.82) (0.84) (1.59) (1.89) (2.41) (2.58)
Table 3
Summary of one way ANOVA of ghost crab population densities at eight beaches.
ANOVA table df MS F P Fcrit
Treatment (between sites) 5 18 830 12.81 <0.0001 3.04
Residual (within sites) 714 1 470
Total 719
Table 4
Summary of one way ANOVA of ghost crab burrow sizes from eight surveyed
beaches.
ANOVA table df MS F P Fcrit
Treatment (between sites) 5 1646 11.02 <0.0001 3.15
Residual (within sites) 264 149.3
Total 269
burrow diameters recorded at both the medium-used and high-
used beaches (Bonferroni, p<0.0001). However, no significant
differences were observed between the means of burrow diame-
ters at the medium-used and low-used beaches (Bonferroni, p>
0.05).
4. Discussion
4.1. Effect of human use and modification of beaches and dunes on
ghost crabs
The objective of this study was to determine the ecological
impacts of human activity on sandy beaches at selected sites in the
Central Region of Ghana as a case study. Ghost crab burrow density
and sizes were used as the main indicating factor coupled with
other relevant physical environmental conditions. Three different
categories of beaches were investigated: high-used, medium-used
and low-used, based on the intensity of identified human activities.
Results showed that ghost crab burrow densities at the low-used
beaches were twice or more times higher than those recorded at
the medium-used and high-used beaches. Similar patterns were
observed in the mean burrow diameters, where mean diameters
recorded at the low-used beaches were almost twice or more the
diameters recorded at the medium-used and high-used beaches.
The results indicate that physical variables were very consistent
and did not vary statistically among the different categories of
beaches and hence appeared unlikely that physical environmental
factors are the main causes of the observed differences in mean
Fig. 4. Temporal variation (mean ±S.E) in ghost crab burrow densities recorded at
the six study beaches in the Central Region of Ghana.
burrow densities and burrow diameter among sites. It is however
more likely that these spatial differences in ghost crab burrow
densities and diameters are as a result of the varying human
disturbances identified on the sites.
Along this study area, human modifications of beaches have
been carried out by residents (for residential facilities), investors
(for tourism activities) and the municipal authorities (for social in-
frastructure development). These have resulted in the conversion
of sandy beaches and dunes into highly utilized urbanized areas
patronized by both local residents and tourists. Such multiple ur-
ban uses of sandy beaches also present a major challenge to coastal
managers when trying to distinguish which one may be responsi-
ble for the decrease or loss of biodiversity (Veloso et al., 2009).
In this study, beaches with the highest human use and mod-
ification had the lowest ghost crab populations. Similar observa-
tions of the effects of various human activities on Ocypode spp
have been documented in several recent studies, such as trampling
(Noriega et al.,2012;Reyes-Martínez et al.,2015), beach sand min-
ing (Jonah et al., 2015b), off-road vehicles (Lucrezi and Schlacher,
2010;Schlacher and Lucrezi, 2010), beach sweeping (Yong and
Lim, 2009) and dune modification and shoreline armouring (Lu-
crezi et al.,2009b;Hubbard et al.,2013). Such activities cause di-
rect changes to the habitat, destroy the dune systems, change the
92 F.E. Jonah et al. / Regional Studies in Marine Science 2 (2015) 87–94
natural physical characteristics of the beaches, eliminate food
sources, and reduce habitats and shelter areas (Reyes-Martínez
et al., 2015).
In this study, we found a strong negative correlation between
the number of beach users and ghost crab density. Trampling
resulting from beach users is known to cause the clogging of ghost
crabs burrows, the direct and indirect crushing of ghost crabs
(Defeo et al., 2009). In Ghana, most urban beaches are open to
visitors. However, poor accessibility is a major reason for the low
usage of certain beaches such as the beaches classified as ‘low
use’ in this study. Urban beach patronage is especially high during
weekends and on national holidays. Large numbers of individuals
patronize the area to engage in recreational activities. Field
surveys for this study were carried out on early Sunday mornings;
following recreational activities on urban beaches on Saturdays.
The low densities of ghost crab burrows encountered at the high
and medium used beaches may therefore be partly associated with
the high levels of trampling that occurred on the preceding day.
Burrows of ghost crabs need to be maintained daily and especially
at night when they are most active (Wolcott, 1978). Hence, it is
reasonable to assume that low records of burrows at the ‘high
use’ beaches during early morning surveys following the previous
day’s recreational activities directly corresponds to the actual
densities of ghost crabs present on those beaches (Valero-Pacheco
et al., 2007). Similar observations have been made in other studies
including Neves and Bemvenuti (2006) and Noriega et al. (2012).
The two species of ghost crabs found in Ghana are Ocypode
africana and Ocypode cursor. The former is known to inhabit the
supratidal zone and the latter both the intertidal and supratidal
zones (Lucrezi and Schlacher, 2014). In all, the surveys found ghost
crab burrows were located across the beach face, from the low tide
line to the base of erosion scarp, shore armour or vegetation line
on the beach. However, at the Castle and Philip Quaicoe beaches,
there were no records of ghost crab burrows at sections with signs
of intense trampling but not affected by tidal swash. Burrows were
found to occur at other sections of the same beaches with signs
of equally intense trampling, but influenced by tidal actions and
also at sections not influenced by tides and had very low signs
of trampling. It is likely that trampled areas not influenced by
wave run-up are less suitable for ghost crab burrow construction
since soils from those areas are less compact (less stability for
burrow construction). It is also possible that the effect of trampling
may be reduced by periodic wave run-up, which may increase the
compactness of sediment and consequent stability of burrows.
Driving of all-terrain vehicles (ATV) was occasionally observed
at the Castle beach. The use of these vehicles is likely to have
contributed to some direct and indirect mortality of ghost crabs.
The use of ATVs and other off-road four wheel vehicles have been
identified in several studies to negatively affect the population of
ghost crabs and other invertebrates in the intertidal area (Moss
and McPhee, 2006;Schlacher and Morrison, 2008;Thompson and
Schlacher, 2008). Ghost crabs may also be vulnerable to crushing
whilst in their burrows by such four wheel drive vehicles (Hobbs
et al., 2008) even though such crab mortalities may be strongly
dependent on burrow depth (Schlacher et al., 2007).
Similarly, ghost crab burrow densities were observed to be sig-
nificantly low at the beaches that receive more frequent beach
cleaning with brooms (Castle and Philip Quaicoe). These are done
to make beaches more appealing to visitors. Beach sweeping to re-
move rubbish, natural debris and to improve the aesthetic appeal
of the beach can cause disruption in the natural ecological pro-
cess and modify beach ecosystems (Gheskiere et al.,2005;Dav-
enport and Davenport, 2006). At the study sites, beach cleaning
took the form of litter picking and sweeping of the shoreline and
adjacent dunes. Similar beach cleaning activities were observed
by Yong and Lim (2009) in their study of beaches in Singapore.
They observed that while litter picking may not be damaging to
the shore, sweeping can disturb the sand surface and cover up the
ghost crab burrows, or destroy the sand piles made by the crabs. In
addition, Yong and Lim (2009) observed that beach sweeping re-
moves sea wrack and other marine debris that can serve as food
sources for ghost crabs and other strandline species that in turn
may be fed on by ghost crabs. Veloso et al. (2009) observed that
beach cleaning not only directly compromise the survival of At-
lantorchestoidea brasiliensis by reducing its population abundance,
but also indirectly remove the stranded material, which can be uti-
lized by lower trophic levels.
The effects of various aspect of beach and dune modifications on
ghost crab populations have been studied, including nourishment
and bulldozing (Peterson et al., 2000), shoreline armouring (Barros,
2001;Lucrezi et al.,2009a;Aheto et al.,2011) and urbanization
(Xiang and Jingming, 2002;Souza et al.,2008;Magalhaes et al.,
2009;Noriega et al.,2012). Undertaking coastal urban projects,
such as construction of beachfront tourist facilities and residential
infrastructure usually involves clearing or modification of dune
vegetation. With time, most of such facilities become threatened
by sea erosion needing additional engineering interventions such
as nourishment, bulldozing and shoreline armouring (Nordstrom,
2000). Such coastal developments and interventions may directly
affect the habitat size and range of ghost crabs which become
trapped between coastal development on the terrestrial side and
tidal actions on the other side.
Ghost crabs are known to construct their burrows with respect
to the level of the drift line (Noriega et al., 2012). On beaches
with significant human modifications, such as shoreline armours
and urbanized dunes, the flexibility of ghost crabs to migrate up
and down the beach in response to changing tidal levels may
become limited. Ghost crabs may only have the option of migrating
across the beach face to find more suitable habitats (Lucrezi et al.,
2009b). Seawalls, clearing of dune vegetation and construction on
dunes may prevent access or limit the mobility of ghost crabs to
food sources. At the Ola beach where part of the original dune
vegetation had been cleared and a wooden beachfront tourist
facility installed, burrows were found up to about 18 m inland from
the base of the erosion scarp. Here, ghost crabs were observed to
inhabit very shallow burrows; such as a 3 cm burrow occupied by
a crab with carapace width of about 1.10 cm at almost 7 m inland
of the erosion scarp line. Ghost crabs in this area may however
receive a trophic subsidy from food scraps left by visitors. Along
several beaches of the Central Region where vegetation are intact,
ghost crabs burrows have been found as far back as 40 m from the
beach vegetation line and thus demonstrating the ability of ghost
crabs to migrate up the beach vegetation in search of food. Other
studies such as Jones and Morgan (2002) have also observed ghost
crabs constructing burrows some distance of the actual beach, up
to 200 m from the water’s edge.
4.2. Beach management and ecology
Beach management programmes in many developing nations
including Ghana have largely focused on protecting life and
property as well as enhancing the recreational and aesthetic value
of the beaches for tourism, with little or no attention given to beach
living organisms such as the ghost crabs. Such programmes have
caused severe impacts on the factors that support the survival of
many living organisms that use the beach environment as habitat,
nesting or spawning grounds in both developed and developing
countries (Nordstrom,2005;Cartwright,2014). This could lead to
a possible loss of coastal and marine organisms that depend on the
beach either as habitat or as spawning grounds (e.g. ghost crabs
and sea turtles). There is the need therefore, to reduce the negative
F.E. Jonah et al. / Regional Studies in Marine Science 2 (2015) 87–94 93
effects of human activities and the impacts of beach management
programmes on beach living organisms.
Management interventions to issues of human use of beaches,
and regulation in Ghana have been reactive rather than strategic
(Boateng, 2006). Most often, beach management regulations seek
to control commercial activities such as sand mining, but regula-
tion on recreational use is less strict. The limited control on the
recreational use of beaches has led to ad hoc beach development
and siting of unapproved infrastructure for recreational purpose.
The unregulated recreational use of beaches and ‘‘ad hoc’’ infras-
tructure development may cause ‘unacceptable’ changes to natural
systems and thus influencing negatively on ghost crabs and other
living organisms on the beach.
Apart from scavenging scraps and dead organisms on the beach,
ghost crabs contribute significantly to the ecological functioning of
the beach. Schlacher et al. (2011) identified a strong correlation
between higher ghost crab abundance at sites with higher
vegetation. It is assumed that the ghost crabs borrows facilitate
soil aeration and percolation and thus enhance the growth of
vegetation. Therefore, the reduction in ghost crab population
may affect beach vegetation. Vegetation is an important habitat
component for ghost crabs for reasons such as; plants provide more
shade, which protect the ghost crab from harsh physical conditions
caused by high temperature and high evaporation rates, and taller
vegetation may provide better camouflage from predators such as
birds and foxes. Furthermore, leaf litter from plants influences the
abundance and distribution of invertebrates in coastal dunes.
There is the need to pursue direct ecological beach management
policies and interventions to protect the ecosystems of recreational
beaches. Direct management of the ecological resources of beaches
is less prominent in developing countries such as Ghana. The au-
thors recommend that coastal authorities should develop plans
for recovery and protection of beach species and their habitats.
The following direct beach ecological management programmes
is therefore suggested; protection of birds nesting grounds on
beaches, creation of small pockets of sanctuary and habitats on
recreational beaches to protect ghost crabs and other beach organ-
isms. The size of a beach sanctuary will depend on the beach size
and the conservation needs. However, we assume that a minimum
of 100 m to a maximum of 1 km of undisturbed beach and adjoin-
ing backshore maintained at various locations along the shoreline
depending on conservation needs can be useful. In addition, there
is the need to control the destruction of sand dunes and regulate
human activities, particularly, sand mining and other the ‘‘ad hoc’’
recreational infrastructure development along the coast.
5. Conclusion
In this study, beaches and dunes with low human use and modi-
fication recorded significantly higher ghost crab densities and bur-
row sizes compared to beaches with medium to high human use.
Since physical and environmental parameters were similar across
the sites, human activities are the most likely cause of the observed
differences in burrow size and abundance of ghost crabs. Contin-
ued unregulated anthropogenic use of beaches in Ghana may lead
to increased negative effects on habitat conditions; compromising
the survival of beach fauna and resulting in wider implications for
local marine and coastal resources conservation.
Acknowledgements
This research was funded by Seafront Environmental (www.
seafrontenvironmental.com). We are very grateful to Robert Ebo
Jonah and Wisdom Agbeti for their help during the field data
collection.
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http://dx.doi.org/10.1163/001121609X12530988607470.
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Mining of sand and stone from the coasts provides an inexpensive source of materials for the construction industry while providing income to contractors. However, these activities come at a cost to the coastal environment and pose a threat to the tourism industry along the Ghanaian coast. This paper identified the various types of coastal sand and stone mining activities, the level at which they are undertaken and covers the trends in coastal erosion along the coast of Cape Coast, Ghana. ArcGIS (ESRI, Redlands, CA, USA) and Digital Shoreline Analysis System (DSAS; ESRI) tools were used to determine short-term (2005–2012) coastline changes using 2005 and 2012 coastlines data. This study estimates that tipper-truck-based beach sand mining activities alone account for the loss of about 285,376 m/year of sand from the littoral zone in the Cape Coast area. It was also established that the average erosion rate for the Cape Coast area within the seven year period is 0.85 m/year with two areas recording high erosion rates of 4.35 m/year and 4.25 m/year. The study concludes that sand mining is the main cause of erosion along the coastline of Cape Coast.