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Evolution of mangrove crabs distribution in the Atlantic coast ofCameroon
Ndongo Din1*, Vanessa Maxemilie Ngo-Massou1,2, Ernest Kotte Mapoko1, Marie Christine Essoh
Mongo1 and Guillaume Leopold Essome-Koum1
1Department of Botany, Faculty of Science, the University of Douala, P.O. Box: 8948, Douala-
Cameroon,
2Department of Biological Sciences, High Teacher’s Training College, the University of Yaounde I,
P. O. Box 47 Yaounde, Cameroon
*Tel. (237) 99 83 37 63/79 64 70 68; Email: ndongodin@yahoo.com
Mangroves forests are sheltered a diverse and distinctive macro-faunal assemblage mainly
made of brachyuran crabs. These invertebrates operate relevant ecological roles in terms of
structure and function in mangroveecosystems. This study aims to check off investigations of
mangrove crabs in Cameroon. Study areas were selected between Limbe and Kribi where
mangrove stands are dominated by Rhizophora spp.Transectswere opened in the forest
perpendicularly to the main channel, from land to water in order to identify zonation. Inside
each vegetation belt, a plot of 10 × 10 m2 was established to observe crabs using three
sampling methods (excavation, sight harvest and visual count). Scientific data have been
produced by four teams since 1975. The results present 33 species among which some have
not been identified at the species level. The harvested species are grouped into19 genera and
ten families. Sesarmidaewith eleven species is the most species richness and the most
abundant family. Grapsidae,Ocypodidaeand Portunidaeare respectively represented by seven,
four and three species. Gecarcinid crabs are represented by a single genus with two species as
Panopeidaewhile the last fourfamilies (Macrophthalmidae, Majidae,Pilumnidae and
Varunidae)are represented by a single species. PerisesarmakamermaniDe Man 1883 appear to
be the most abundant species while ArmaseselegansHerklots1851,
PerisesarmaalbertiRathbun 1921 and P. huzardiDesmarest 1925 are the most frequent.
Mangroves in Cameroon are critically threatened by human activitiesmainly around large
cities. Management and conservation strategies are necessary to protect the ecosystem
properties and its biological diversity. Investigations are going on in the northern and the
southern parts of the actual study area in order to improve the Cameroon mangrove crabs
diversity.
Keywords: brachyuran crabs, Cameroon Estuary, diversity,frequency, vegetation belt.
1
INTRODUCTION
Mangroves are tropical and subtropical forest ecosystems, composed by several
elements associated in the land-sea interface, which delays coastal erosion, contributes to
expansion of the continent and acts like a buffer zone in the areas prone to the cyclones and
supports significantly fisheries production (Din and Baltzer 2008). Mangroves are also salt
tolerant trees which evolved from rainforest trees, unique in their adaptation to the distinct
environmental requirements of the intertidal habitat (Tomlinson 1986; Ellison et al. 1999).
In these intertidal forests, terrestrial species have re-adapted to marine life, and marine
species have undergone the transition to terrestrial species. Mangrove species are dominated
by a diverse and distinctive macro-faunal assemblage mainly consisting by snails, crabs and
even fish (Ravichandran and Wilson 2012), whichexert a strong influence on ecosystem
functions and regulate mangroves forests productivity (Cannicci et al. 2008).
Brachyuran crabs are dominant in most mangrove habitats, high in species number,
abundance and biomass compared with many other animals (Lee 1998), thus adequate for
modelling settlement in these systems (Paula et al. 2003). They are dominated by various
burrowing decapods (Kristensen 2008). About 93 families and 38 subfamilies have so far
been discovered worldwide which 6 793 are valid species (Ng et al. 2008). Six of these
families are mostly represented in and around mangrove forests: Gecarcinidae, Portunidae,
Ocypodidae, Xanthidae, Sesarmidae and Grapsidae (Lee 1998). Fiddler crabs are considered
to be the most abundant crabs in mangroves (Smith et al. 2009). They form an important link
between the primary detritus at the base of the food web and consumers of higher trophic
levels (Sousa and Dagremond 2011).
Crab burrowing activities significantly decrease ammonium and sulphide
concentrations in mangrove soil, thus positively benefiting mangrove productivity (Ferreira et
al. 2007). By consuming litter, crabs can promote nutrient mineralization and recycling within
the forest. Furthermore, their role as bioturbators doubtlessly contributes to alter
physiochemical characteristics of the soil (Kristensen 2008) and enhance its capability to
retain organic carbon (Andreetta et al. 2014). More recently, however, other mesocosm
experiments carried out in East Africa, showed that the beneficial effect of Ucaspp. activities
on mangrove soil biogeochemistry can be strongly impaired by organic waste discharge.
Mangroves in Africa cover over 3.2 million ha, corresponding to about 20 % of its
global coastline coverage, with approximately 1.5 million ha located along the Atlantic coast
(MassóiAlemán et al. 2010). As a consequence of the enormous anthropogenic pressures and
multiple threats, a decline of more than 25 % of the Western African mangroves has been
observed over the past 25 years (Giri et al. 2011). In West Africa, Cameroon harbours
approximately 2000 km2 land-area of mangroves, distributed along the coast of the Guinean
gulf (Din and Baltzer 2008). Almost 53,216 ha of the Cameroon’s mangrove forests have
been lost over the last 13 years (Spalding et al. 2010). These disturbances in mangroves have
been attributed to a combination of factors such due to the absence of adequate legislation
regarding mangrove protection, and pollution in the peri-urban settings (Nfotabong-Atheull et
al. 2013).
However, mangrove macrobenthos diversity and functionality are relatively poorly
known compared to other aspects of these productive ecosystems, such as floristics and
trophic ecology (Lee 1998, 2008; Nagelkerken et al. 2008). Thus, it is of great importance to
determine the macrobenthos assemblages of the mangroves. Information on the macrobenthos
of West African mangroves is limited compared to the more comprehensive research
conducted in East Africa (Cannicci et al. 1993, 2008, 2009;Dahdouh-Guebas et al. 2000,
2004; Hartnoll et al. 2002; Pape et al. 2008;Vannini et al. 2008a, 2008b). For Cameroon, the
Brachyuran crab data analyzed in this survey have been carried out by Boyé et al. (1975),
2
Guiral et al. (1999), Longonje (2008) and Ngo-Massou et al. (2012, 2014). So, the aim of this
study is to check off investigations of mangrove crabs in Cameroon.
MATERIAL AND METHODS
Study area
The study was carried out between Limbe and Kribi(Figure 1) where mangrove stands
are dominated by Rhizophora spp. The area is dominated by two types of climate. In the north
and center part, the climate belongs to a particular equatorial regime called Cameroonian
regime, characterized by a long rainy season (March–November) and a short dry season
(December–February) with annual average temperature around 26.7 °C (Din et al. 2008). In
the south (Kribi), the climate is a typical equatorial regime with four seasons (two rainy
seasons and two dry seasons well individualized),marked by high and stable temperatures
around 28.7 °C.
Heavy annual rainfalls are observedfrom more than 5000 mm at Limbe and decreased
to about 3000 mm at Kribi. In the spring tide, the tidal regime reaches 3 m in the Cameroon
Estuary, 1.2 m in the mouth of Nyong and 1.5 m in Kribi(Giresseet al. 1996).The annual
variation in salinity ranges between 0 and 20 ‰.The relative humidity is always close to the
rate of saturation. Soils are grey or black muds, of silty, sandy or clayey texture, derived from
fluvial sediments. The content of organic matter is relatively weak, 1 to 3 % with carbon:
nitrogen ratio (C:N) often lower than 10 in the whole area.
The flora consists essentially of tree species. The herbaceous stratum represents < 1 %
of all vegetation. However, the flora remains poor with Rhizophoraracemosa GF Meyer being
largely the dominant vegetation in all sites. The faunal component includes vertebrates, such
as birds, reptiles and fish, and a wide range of invertebrates, mainly crabs and molluscs which
constitute the bulk of benthic diversity in the region (Ngo-Massou et al. 2012).
Macrobenthos survey
For some studies, the mangrove forest was divided from landward to seaward into
three main zones: landward fringe, tree species belts, sand flat or mudflat. Transects between
70 and 500 m were established across the zoneaccording to the vegetation spread. To assess
the abundance and density of the crab populations, 10 × 10 m2 quadrats were sampled inside
each zonation throughout transect. Several techniques have been used for sampling mangrove
crabs: excavation, crab catch, visual count and pitfall depending species found.
However, all these methods are markedly affected by the heterogeneity of the
environment, nocturnal behavior and conspicuous species. Crabs were sedated in cold water
for a few minutes, washed and stored in 70 % alcohol for later operations. Identifications have
been made in the field or later in the laboratories and lastly by specimens and photos sent to
other specialists, mainly in Italy.
Measurement of parameters
At low tide, a 20 cm deep hole has been dug into the ground. Some physicochemical
parameters (conductivity, temperature, salinity and pH) were measured in situ from this
groundwater using portable field equipment (WTW: Standard Conductivity Cell, TetraCon
325 and pH Meter 330/7/SET).
Data analysis
3
The following ecological parameters were assessed to describe the structure and
composition of crabs (absolute density: number of individuals/m2; relative density: number of
individuals per species/total number of individuals; species occurrenceor frequency (number
of plots the species has been seen/total number of plots); specific diversity has been expressed
in Shannon-Weaver index (H′) and Pielou’s evenness (J) or equitability index).
The relationship between salinity and conductivity was established and evaluated
using Pearson’s correlation. The Mann-Whitney (U) test was also used to observe differences
between transects. Spearman’s Rank Correlation Test was used to determine the relationship
between environmental parameters and biotic variables (abundance, diversity and species
richness).
RESULTS AND DISCUSSIONS
Migrations
The behaviour of crabs changes according to tides. As many studies occurred in low
tide, crabs migrations varied from deep burrow to plant roots and trunks. Many species have
been found in different substrates and used different areas to avoid to be caught. Many crabs
can’t be easily observed in mangrove area dueto their reactions of defence. It’s therefore
difficult to assume that the place of harvesting correspond to their effective habitat. Some
species used camouflage because of the slowness of their migration. Others preferred to be
around the place of concealing. The last group and the most abundant is consisted of swift
species which can be observed anywhere. With a few exceptions (ChiromantesangolenseDe
Britocapello 1864, Goniopsis spp., Perisesarma spp.), the migrations of species are unique
(Table 1).
Inventory
Up to now, 33 species have been recorded among which some have not been clearly
identified at the species level. The harvested species are grouped into 19 genera and ten
families. Sesarmid represents the most species richness and the most abundant family. Inside
this family, five genera have been recorded and eleven species. The second family in terms of
species richness is Grapsidae with seven species divided into three genera, followed by
Ocypodidae with four species (two genera) and Portunidae with three species grouped also
into two genera. Panopeidae is represented by two genera with a sole species each. Gecarcinid
crabs contained a single genus (Cardisoma) with two species while the four last families
(Macrophthamidae, Majiidae, Pilumnidae and Varunidae) are represented by a sole species
(Table 1).
The different surveys carried out in the Cameroon mangrove ecosystems have shown
33 species where the ongoing studies have contributed by the addition of nine species
belonging to seven families among which four have been already described in the area and
three other families, Majidae,Macrophthalmidaeand Varunidaewith a single species each. As
in most mangrove forests, crabs dominates the macrobenthos (Lee 2008;Nagelkerken et al.
2008) of mangrove ecosystems in this country. Most identified species in Cameroon
mangrove forests are the same since the beginning of scientific data collection, indicating the
relative stability of the macrobenthic fauna in this ecosystem.
4
Table 1: Inventory and migrations of mangrove crabs found in Cameroon.
Family Species Collected sites Substrate Migration/behaviour
Gecarcinidae
Cardisomaarmatum Limbe, Tiko, Douala,
Londji
Sand, mud Burrows, land
Cardisomasp. Tiko Sand, mud Burrows
Grapsidae
Goniopsiscruentata Londji, Kribi Mud Under litter, plant roots and
trunk
G. pelii Limbe, Tiko, Douala,
Londji
Mud Under litter, plant root and
trunk
Grapsusgrapsus Limbe, Kribi Rocky Rocky bottom
Pachygrapsusgracilis Limbe, Tiko Sand, mud Plant roots
P. transverses Limbe, Tiko, Douala,
Yoyo, Kribi
Mud Burrows
Pachygrapsus sp.1 Limbe, Tiko Rocky Rocky bottom
Pachygrapsussp. 2 Douala Mud Under the litter
Macrophthalmidae Macrophthalmus sp. Douala Mud Burrows
Majiidae Majasp. Londji Sand Water
Ocypodidae
Ocypodeafricana Limbe, Kribi Sand Burrows
O. cursor Kribi Sand Burrows
O. ippeus Limbe Sand Burrows
Ucatangeri Limbe, Tiko, Douala,
Londji
mud Burrows
Panopeidae
Panopeusafricanus Yoyo Mud Water
Eurypanopeusblanch
ardi
Limbe, Tiko, Douala Sand, mud Under litter
Pilumnidae Pilumnopeusafricanu
s
Limbe, Tiko, Douala Sand, mud Under litter
Portunidae
Callinectesamnicola Limbe, Tiko Mud Water
C. pallidus Limbe, Tiko, Douala Sand Water
Portunusvalidus Limbe, Tiko Mud, sand Water
Sesarmidae
Armaseselegans Limbe, Tiko, Douala,
yoyo, Londji, Kribi
Mud, sand,
rocky
On plant roots and trunk
Chiromantesbuettikof
eri
Limbe, Tiko, Douala,
Yoyo, londji
Mud, sand Under the litter
C. angolense Limbe, Tiko, Douala,
Yoyo, londji
Mud Muddy burrow, dead wood,
under the litter
Metagrapsuscurvatus Limbe, Douala,
Yoyo, Londji, Kribi
Mud Muddy burrow
Perisesarmaalberti Limbe, Tiko, Douala,
yoyo, Londji, Kribi
Mud Under the litter and dead
wood, burrows
P. huzardi Limbe, Tiko, Douala,
yoyo, Londji, Kribi
Mud Burrows
P. kamermani Douala, yoyo, Londji,
Kribi
Mud Under the litter and dead
wood, burrows
Sesarmasp. 1 Limbe, Tiko Sand, mud Under the litter and dead
wood
Sesarmasp. 2 Douala, yoyo, Londji,
Kribi
Mud, sand Under the litter and dead
wood
Sesarmasp. 3 Douala Mud Under the litter and dead
wood
Sesarmasp. 4 Douala Mud Under the litter and dead
wood
Varunidae Helicesp. Douala Mud Under litter
The checklist of the mangrove and freshwater Decapod Crustaceans of West Africa
has indexed 39 crab species (Cumberlidge 2006). Twenty species identified in this study are
5
common, given the similarities in the biological composition of Atlantic mangroves. The
sevensesarmid species reported in the above checklist have been clearly identified. A new
contribution of about four other species (Sesarma spp.) might improve the inventory of
African Atlantic mangrove crabs. The ongoing procedure of identification up to the specific
level could therefore generate another genus among the Sesarma species or simply reduce the
number of species (Figure 2).
The four grapsid species reported were found with another contribution of two other
species belonging to the genus Pachygrapsus. Three of the four portunid species reported
were found, except Callinectesmarginata. Two Gecarcinid species belonging to the genus
Cardisomawere found. It’s possible that the unidentified specimens at the species level
(Cardisoma sp.) correspond toCardisomaweileriSendler 1912 already reported in the
checklist. Two of the eight xanthid species (Panopeusafricanus and Pilumnopeusafricanus)
also reportedhave been transferred to two new families,Panopeidae and Pilumnidae obtained
in the present study. Seven ocypodid species have been reportedin that checklist; three of
them have been already foundin Cameroon mangrove ecosystems. Beside the four missing
species (Calabariumcrinodyte Manning &Holthius 1981, Ecphantormodestus Manning
&Holthius 1981,Lilleyanellaplumipes Manning &Holthius 1981 andTelmatothrixpowelli
Manning &Holthius 1981)there is a contribution with another species(Ocypodeippeus Olivier
1804). In the same order, the family of Varunidae has been found with a sole species (Helice
sp. De Haan 1833) but different from that reported in the checklist (Cyclograpsus integer H.
Milne Edwards 1837).
West Africanmacrobenthos fauna remains poor in both generaUca and Cardisoma
especially. The first genus is represented by a single species (U.tangeriEydoux 1835) and the
second genus by two species (C. armatumHerklots 1851 and C. weileri).Elsewhere, they were
reported to include several species (Ng et al. 2008; Lim and Wong 2010). These two crabs
appeared as the most terrestrial crabs of mangroves environment.
Finally, surveys concerning mangrove crabs inventory in Cameroon have significantly
improved the West African aquatic crab’s diversity. In spite of changes in biological
nomenclature, three additional families have been recorded in the country, meaning that West
African mangrove and freshwater crabs belong at least to twelve families instead of nine. In
the same order, four genera and 13 species, different from the checklist up cited, had
improved the inventory from 25 to 29 genera and from 39 to 52 species of crabs.
Contributors
The inventory of mangrove crabs in Cameroon produced scientific data towards the
end of the 20th century. The first studies were carried out in the Cameroon Estuary, especially
in the Wouri River mangroves, around the city of Douala. The evolution of this inventory
depends on about five teams among which two local research groups. From seven species
published by Boyé et al. (1975), nine others have been added near a quarter century later by
Guiral et al. (1999). In terms of time, this result showed clearly that this question was not the
top interest of scientific surveys in the country. Lest than a decade later, Longonje (2008)
brought this inventory to 22 species (six more species added) and our research group
hadimproved these results by two species (Ngo-Massou et al. 2012) and actually nine species
in the ongoing surveys. The first years of the 21st century havebeen more productive for
6
mangrove crabs inventory in Cameroon. In about a decade, species richness has increased
with eight families, eleven generaand 17 species (Table 2).
The evolution of the inventory has shown a sort of specificity in each survey. Up to
now, none work had recorded all crab species reported by previous data. Each team had at
least two species which have not been reported by further data. Boyé et al. (1975) had
reported aloneOcypodeippeus and Pachygrapsusgracilis;Guiral et al. (1999) had recorded the
same withEurypanopeusblanchardiandPilumnopeusafricanuswhileLongonje (2008) added
alone Grapsusgrapsus, Pachygrapsussp.1 and Sesarma sp.1. For both last species, it must be
noted that the final identification could lead to species encountered by the last team,
Pachygrapsus sp.2 and one of the threeunidentified species of the genus Sesarma (Table 2).
Table 2: Evolution of mangroves crabs inventory in Cameroon. Some specimens have not been identified at the
species level.
Boyéet al. (1975) Guiral et al. (1999) Longonje (2008) Ngo-Massouet al.
(2012)
Unpublished data
Callinectesamnicola
C. pallidus
Chiromantesangolense
Goniopsispelii
Ocypodeippeus
Pachygrapsusgracilis
Ucatangeri
Armaseselegans
Cardisomaarmatum
Eurypanopeusblanchardi
Metagrapsuscurvatus
Panopeus africanus
Perisesarmaalberti
P. huzardi
Pilumnopeus africanus
Sesarmabuettikoferi
Grapsusgrapsus
Ocypodeafricana
Pachygrapsustransversu
s
Pachygrapsussp.1
Portunusvalidus
Sesarmasp.1
Perisesarmakamermani
Sesarmasp.2
Cardisomasp.
Goniopsiscruentata
Helicesp.
Macrophthalmussp.
Maja sp.
Ocypodecursor
Pachygrapsussp.2
Sesarmasp.3
Sesarmasp.4
Distribution
The distribution of mangrove crabs along the Atlantic coast of Cameroon appears to
be few linked to the nature of the substrate. From Limbe to Kribi, mangroves are grown on
rocky, sand and mostly muddy substrates. Three species (Armaseselegans,
Perisesarmaalberti and P. huzardi) have been found in the six study sites while ten species
have been reported only in one site (Table 3). The mangrove ecosystem of Limbe has
appeared to get the most number of species of crabs (21), followed by the Douala mangrove
stands (20) and Yoyo mangroves being the last. Nevertheless, the low number of species in
Yoyo mangrove site could be related to the low number of studies carried out in this site
because of the distance and the accessibility conditions.
Sesarmid crabs (12 species) were best represented in terms of species richness and
they were the most abundant (85 %) in the Wouri Estuary mangroves (Ngo-Massou et al.
2012). These crabs are reported to be the most diverse in the mangrove forests in the world
(Ashton et al. 2003). They form an important organic component because they play a major
role in the structure and functioning of mangrove ecosystem (Dahdouh-Guebas et al. 2011;
Van Nedervelde et al. 2012). Recently, some authors suggested a possible ‘mutual
relationship’ between sesarmid crabs and mangroves. Under this model, mangroves provide
food and a suitable habitat for the crabs, which in turn reduce competition through propagule
predation (Bosire et al. 2005; Cannicci et al. 2008).
7
Table 3: Frequency distribution of crabs in the coastal mangroves of Cameroon.
Species Limbe Tiko Douala Yoyo Londji Kribi Frequency
Armaseselegans + + + + + + 1
Callinectesamnicola + + - - - - 0.33
C. pallidus + + + - - - 0.50
Cardisomaarmatum + + + - + - 0.67
Cardisomasp. - + - - - - 0.17
Chiromantesangolense + + + + + - 0.83
C. buettikoferi + + + + + - 0.83
Eurypanopeusblanchard
i
+ + + - - - 0.50
Goniopsiscruentata - - - - + + 0.33
G. pelii + + + - + + 0.83
Grapsusgrapsus + - - - - + 0.33
Helicesp. - - + - - - 0.17
Macrophthalmus sp. - - + - - - 0.17
Maja sp. - - - - + - 0.17
Metagrapsuscurvatus + - + + + + 0.83
Ocypodeafricana + - - - - + 0.33
O. cursor - - - - - + 0.17
O. ippeus + - - - - - 0.17
Pachygrapsusgracilis + + - - - - 0.33
Pachygrapsussp.1+ + - - - - 0.33
Pachygrapsussp.2- - + - - - 0.17
P. transversus + + + + - + 0.83
Panopeus africanus - - - + - - 0.17
Perisesarmaalberti + + + + + + 1
P. huzardi + + + + + + 1
P. kamermani - - + + + + 0.67
Pilumnopeus africanus + + + - - - 0.50
Portunusvalidus + + - - - - 0.33
Sesarmasp.1+ + - - - - 0.33
Sesarmasp.2- - + + + + 0.67
Sesarmasp.3- - + - - - 0.17
Sesarmasp.4- - + - - - 0.17
Ucatangeri + + + - + - 0.67
Total 21 18 20 10 13 12 /
+ = Present ; - = Absent
Ucatangeri was the only species encountered in all studies, while Goniopsispelii and
Chiromantesangolense were found by four authors.Ucatangeri and Ocypode spp. arethe only
species in the study area which were not counted since they do not live under the forest
canopy.They are found in the muddy or sand river banks with no tree cover for the first
species and only in the sand river banks for the second. The phenomenonhas been observed
8
for U.tangeri in east African forests where this speciesoccupies a vast whole of microhabitats
(mudflats, sand and rocks beaches, zones beyond and inside tide line and mangroves) which is
the equivalents of several ecological niches distinct occupied by several species from
mangroves(Cannicci et al. 2009).
Some species have shown a specific behavior. In particular the species of genera
Cardisoma, Goniopsis,Pachygrapsus, Perisesarma andMetagrapsuswere identifiedas
burrowing crabs,Armasesas climber,Eurypanopeus, Grapsus, Panopeus and Pilumnopeusnon
burrowers and Chiromantesas potentially phytothelmic (Ngo-Massou et al. 2012; Fusi et al.,
unpublished data). The intertidal distribution of these crabs does not appear to be strongly
influenced by sediment type, but some species such as those with arboreal habits are
associated with certain species of mangroves or habitat types withinmangal forest (Cannicci et
al. 1996). The Grapsid, Ocypodid and Sesarmid crabs are restricted with brackish water prone
to daily fluctuations due to the tide, while the Gecarcinid crabs are terrestrial and saw almost
independently of water (Cumberlidge 2006).
Crabs patterns of distribution are related to abiotic conditions and associated biotic
factors (Pedersen et al. 2003; Rodri’Guez-Fourquet and Sabat 2009; Esenowo and Ugwumba
2010). The importance of vegetation in distribution of macro-fauna has been widely studied
(Wang et al. 2005; Zhou et al. 2010). Some species had been shown a preferential distribution
for mangrove plants in the Wouri Estuary river mangroves, perhaps for feeding behavior or
for a suitable refuge. Armaseselegans,Cardisomaarmatum, Chiromantesbuettikoferi and
Perisesarmahuzardi were found in Guibourtiademeusei(Harms), Pandanus candelabrumP.
Beauv., Hibiscus tiliaceusL. andCynometramanniiOliv.belts respectively while
Perisesarmakamermani, PachygrapsustransversusandChiromantesangolense have shown
ubiquitous behaviors (Ngo-Massou et al. 2014). It has therefore become difficult to determine
which plant directly influences their distribution.
Salinity is considered as a key ecological factor in estuarine and coastal zones that are
characterized by a high variability. The crab species do not have the same capacities of
osmoregulation and their physiological answers with respect to various salinities are different
(Nobbs 2003). In the same area, Pachygrapsustransversus,Portunusvalidus and
Chiromantesangolense have been dominated in the high salinity zones (8 - 9 g l-1) while
Cardisomaarmatum was found only in the low salinity conditions (≤ 2.4 g l-1).
Chiromantesbuettikoferi, Sesarma sp.2.andU. tangeri tolerate medium level of salinity. U.
tangeri was only found in the high temperature zones. The temperatures of 24oC to 29°C are
optimum surface temperature to stimulate emergence of Ucaspecies from burrows (Lim and
Wong 2010). However, it’s still difficult to relate crab distribution to salinity instead of
vegetation properties.
Studies have been also carried out to relate crab distribution to distance from water
channels. Some crab species were found in many distance classes, but others were only
encountered in specific interval. All mangrove crabs have some degree of behavioral,
morphological, physiological and biochemical adaptationto their habitat.
Pachygrapsustransversus, Portunusvalidusand Chiromantesangolensehave been found near
channels. Cardisomaarmatumand U. tangeriappeared as the most terrestrial crabs of
mangroves environment (Ngo-Massou et al. 2014).
CONCLUSION
9
The macrobenthos inventory in the Cameroon mangrove ecosystem has been
intensified in the first years of the present century. Significant scientific data on mangrove
crabs have been recorded and ongoing studies might improve the actual results. Investigations
are carrying on in the northern and the southern parts of the actual study area in order to
improve the mangrove crabs diversity.The most worry concerns the degradation of mangrove
stands around important cities (Douala, Kribi and Limbe) due to intensive and uncontrolled
anthropic activities which will lead to the total disappearance of mangrove ecosystems.
REFERENCES
Andreetta A, Fusi M, Cameldi I, Cimò F, Carnicelli S,Cannicci S. 2014. Mangrove carbon
sink. Do burrowing crabs contribute to sediment carbon storage? Evidence from a
Kenyan mangrove system.Journal of Sea Research 85: 524-533.
Ashton EC, Hogarth PJ, Macintosh DJ. 2003. A baseline study of the diversity and
community ecology of crab and molluscanmacrofauna in the Semantan Mangrove
forest, Sarawak, Malaysia. Journal of Tropical Ecology 19: 127-142.
Bosire JO, Kairo JG, Kazungu J, Koedam N, Dahdouh-Guebas F. 2005. Predation on
propagules regulates regeneration in a high-density reforested mangrove plantation.
Marine Ecology Progress Series299: 149-155.
Boye M, Baltzer F, Caratini C, Hampartzoumian A, Olivry JC, Paziat JC, Viliiers JF. 1975.
Mangrove of the Estuary, Cameroon. In: Walsh GE, Snedaker SC, Teas HJ (eds)
Biology and Management of Mangroves. Proceedings of International Symposium,
Honolulu, October 8-11th, 1974. I.F.A.S. Univ. Florida, Gainesville (USA). Pp. 431-
455.
Cannicci S, Ruwa RK, Ritossa S, Vannini M. 1996. Branch-fidelity in the tree crab
Sesarmaleptosoma (Decapoda, Grapsidae).Journal of Zoology London 238: 795–801.
Cannicci S, Burrows D, Fratini S, Lee SY, Smith III TJ, Offenberg J, Dahdouh-Guebas F.
2008. Faunistic impact on vegetation structure and ecosystem function in mangrove
forests: a review. Aquatic Botany89: 186-200.
Cannicci S, Bartolini F, Dahdouh-Guebas F, Fratini S, Litulo C, Macia A, Elisha Mrabu J,
Penha-Lopes G, Jose P. 2009. Effects of urban waste water on crab and subtropical
mangroves of East Africa. EstuarineCoastal and Shelf Science 30: 1-14.
Cumberlidge N. 2006. Inventaire rapide des crustacés décapodes de la préfecture de Boké en
Guinée. In: Wright HE, McCullough J, Saliou Diallo M (eds) Un inventaire biologique
rapide de la préfecture de Boké dans le nord-ouest de la Guinée. RAP Bulletin of
Biological Assessment 41. Washington, DC: Conservation International. Pp. 38-46.
Dahdouh-Guebas F, Mathenge C, Kairo JG, Koedam N. 2000.Utilization of mangrove wood
products around Mida Creek (Kenya) amongst subsistence and commercial
users.Economy Botany 54(4): 513-527.
Dahdouh-Guebas F, Van Pottelbergh I, Kairo JG, Cannicci S, Koedam N. (2004). Human-
impacted mangroves in Gazi (Kenya): predicting future vegetation based on
retrospective remote sensing, social surveys, and distribution of trees. Marine Ecology
Progress Series272, 77-92.
10
Dahdouh-Guebas F, Koedam N, Satyanarayana B, Cannicci S. 2011. Human hydrographical
changes interact with propagule predation behaviour in Sri Lankan mangrove forests.
Journal of Experimental Marine Biology and Ecology 399: 188-200.
Din N, Baltzer F. 2008. Richesse Floristique et Evolution des mangroves de l’Estuaire du
Cameroun. African Geosciences Review2: 119-130.
Din N, Saenger P, Priso RJ, Dibong DS, Blasco F. 2008.Logging activities in mangrove
forests: A case study of Douala Cameroon.African Journal Environmental Science
and Technology 2 (2): 022-030.
Ellison AM, Farnsworth EJ, Merkt RE. 1999. Origins of mangrove ecosystems and the
mangrove biodiversity anomaly. Global Ecology and Biogeography 8: 95-115.
Esenowo IK, Ugwumba AAA. 2010. Composition and abundance of macrobenthos in
Majidun River, Ikorordu Lagos State, Nigeria. Research Journal of the Biological
Sciences5 (8): 556-560.
Ferreira TO, Otero XL, Vidal-Torrado P, Macías F. 2007.Effects of bioturbation by root and
crab activity on iron and sulfur biogeochemistry in mangrove substrate.Geoderma
142: 36-46
Giresse P, Megope-Foonde JP, Ngueutchoua G, Aloisi JC, Kuete M, Monteillet J. 1996. Carte
sédimentologique du plateau continental du Cameroun à1: 200000. ORSTOM, Paris,
France.
Giri C, Ochieng E, Tieszen LL, Zhu Z, Singh A, Loveland T, Duke N. 2011. Status and
distribution of mangrove forests of the world using earth observation satellite data.
Global Ecology and Biogeography20(1): 154-159.
Guiral D, Albaret JJ, Baran E, Bertrand F, Debenay JP, Diouf PS, Guillou JJ, Le Loeuff P,
Montoroi JP, Sow M. 1999. Rivières du Sud: Sociétés et Mangroves Ouest-africaines.
IRD, Paris, France. Pp, 23-36.
Hartnoll RG, Cannicci S, Emmerson WD, Fratini S, Macia A, Mgaya Y, Porri F, Ruwa RK,
Shunnula JP, Skov MW, Vannini M. 2002. Geographic trends in mangrove crab
abundance in East Africa. Wetlands Ecology and Management10: 203-213.
Kristensen E. 2008. Mangrove crabs as ecosystem engineers; with emphasis on sediment.
Journal of Sea Research 59: 30-43.
Lee SY. 1998. Ecological role of Grapsid crabs in mangrove ecosystems: a review. Marine
and Freshwater Research 49: 335-343.
Lee SY. 2008. Mangrove macrobenthos: Assemblages, services, and linkages. Journal of
Sea59: 16-29.
LimSSL, Wong JAC. 2010. Burrow residency and re-emergence rate in a droving species,
Ucavocans (Linnaeus, 1758) and its sympatric associate, U. annulipes (H. Milne
Edwards, 1837) (Brachyura, Ocypodidae). Crustaceana 83 (6): 677-693.
Longonje S. 2008. Distribution, diversity and abundance of crabs in Cameroon
mangroves.PhD thesis, University of York, UK.
MassóiAlemán S, Bourgeois C, Appeltans W, Vanhoorne B, De Hauwere N, Stoffelen P,
Heaghebaert A, Dahdouh-Guebas F. 2010. The “Mangrove Reference Database and
Herbarium”.Plant Ecology and Evolution143 (2): 225-232.
11
Nagelkerken I, Kirton LG, Meynecke JO, Pawlik J, Penrose HM, Blaber SJM, Bouillon S,
Green P, Haywood M, Sasekumar A, Somerfield PJ. 2008. The habitat function of
mangroves for terrestrial and marine fauna: A review. Aquatic Botany 89: 155-185.
Nfotabong AA, Din N, Dahdouh-Guebas F. 2013.Qualitative and
QuantitativeCharacterization of Mangrove VegetationStructure and Dynamics in a
Peri-urbanSetting of Douala (Cameroon): AnApproach Using Air-Borne Imagery.
Estuaries and Coasts36:1181-1192.
Ng PKL, Daniele G, Peter JFD. 2008. SystemaBrachyuroran: part I. An annotated checklist of
extant Brachyuran crabs of the world. Raffles bulletin of Zoology 17: 1-286.
Ngo-Massou VM, Essomè-Koum GL, Ngollo-Dina E, Din N. 2012.Composition of
macrobenthos in the Wouri River estuary mangrove, Douala, Cameroon. African
Journal of Marine Science34(3): 349-360.
Ngo-Massou VM, Essome-Koum GL, Kotte ME, Din N. 2014. Biology and Distribution of
Mangrove Crabs in the Wouri River Estuary, Douala, Cameroon.Journal of Water
Resource and Protection 6: (In press).
Nobbs M. 2003. Effect of vegetation differs among three species of fiddler crabs (Uca spp.).
Journal of Experimental Marine Biology and Ecology 284: 41-50.
Pape E, Muthumbi A, Kamanu CP, Vanreusel A. 2008. Size-dependent distribution and
feeding habits of Terebraliapalustrisin mangrove habitats of Gazi Bay,
Kenya.Estuarine Coastal and Shelf Science 76: 797-808.
Paula J, Dornelas M, Flores AAV. 2003. Stratified settlement and moulting competency of
Brachyuran megalopae in Ponta Rasa mangrove Swamp, Inhaca Island (Mozambique).
Estuarine Coastal and Shelf 56: 325-337.
Pedersen C, Everett B, Fielding P. 2003. Subsistence utilization of the crab
Neosarmatiummeinerti in the Kosi Lakes ecosystem, KwaZulu-Natal, South
Africa.African Zoology 38: 15-28.
Ravichandran S, Wilson FS.2012. Variations in the crab diversity of the mangrove
environment from Tamil Nadu, Southeast coast of India. VLIZ Special Publication
57:152.
Rodri´Guez-Fourquet C, Sabat AM. 2009. Effect of harvesting, vegetation structure and
composition on the abundance and demography of the land crab Cardisomaguanhumi
in Puerto Rico. Wetlands Ecology and Management17: 627-640.
Sousa WP,Dangremond EM. 2011. Trophic Interactions in Coastal and Estuarine Mangrove
Forest Ecosystems. In: Wolanski E and McLusky DS (eds.).Treatise on Estuarine and
Coastal Science. Waltham: Academic Press.Vol 6, pp. 43-93.
Smith FN, Wilcox C, Lessmann JM. 2009. Fiddler crab burrowing affects growth and
production of the white mangrove (Lagunculariaracemosa) in a restored Florida
coastal marsh. Marine Biology 156: 2255-2266.
Spalding M, Kainuma M, Collins L. 2010. World atlas of mangroves. Okinawa, Japan: The
International Society for Mangrove Ecosystems.
Tomlinson PB. 1986. The botany of mangroves Cambridge UnivPress UK. 419p.
Vannini M, Lori E, Coffa C, Fratini S. 2008. Cerithideadecollata: a snail that can foresee the
future? Animal Behaviour76: 983-992.
12
Van Nedervelde F, Koedam N, Bosire JO, Berger U, Cannicci S, Dahdouh-Guebas F. 2012.
The bidirectional relationship between mangrove vegetation and sesarmid crabs:
complex interaction amongst density and composition of vegetation, crab density and
propagule density. VLIZ Special Publication 57: 183.
Wang YD, Xiong BX, Chen CB, Hu HS. 2005. The effect of environment factors on life
activity of Zoobenthos. Journal of Zhejiang Ocean University.Natural Science 42:
644-647.
Zhou X, Cai L, Fu S, Wang W. 2010. Comparative study of the macrobenthic Community in
intertidal mangrove and non-mangrove habitats in Tong’an Bay, Fujian
Province.Biodiversity and Science 18 (1): 60-66.
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