Aquatic Ecology Assessment at Boteka Aquatic Ecology

Transcription

Aquatic Ecology Assessment at
Boteka
Aquatic Ecology
Project Number:
CDC2950
Prepared for:
Feronia PHC
August 2015
_______________________________________________________________________________________
Digby Wells and Associates (South Africa) (Pty) Ltd
(Subsidiary of Digby Wells & Associates (Pty) Ltd). Co. Reg. No. 2010/008577/07. Fern Isle, Section 10, 359
Pretoria Ave Randburg Private Bag X10046, Randburg, 2125, South Africa
Tel: +27 11 789 9495, Fax: +27 11 789 9498, [email protected], www.digbywells.com
_______________________________________________________________________________________
Directors: DJ Otto, GB Beringer, LF Koeslag, AJ Reynolds (Chairman) (British)*, J Leaver*, GE Trusler
(C.E.O)
*Non-Executive
_______________________________________________________________________________________
This document has been prepared by Digby Wells Environmental.
Report Type:
Aquatic Ecology
Project Name:
Aquatic Ecology Assessment at Boteka
Project Code:
CDC2950
Name
Responsibility
Company
Date
Russell Tate (Pr.
Sci. Nat.)
Survey and report
writer
Digby Wells
Environmental
August 2015
Brett Reimers
Report Reviewer
Digby Wells
Environmental
May 2015
Marion Thomas
Report Reviewer
Digby Wells
Environmental
May 2015
This report is provided solely for the purposes set out in it and may not, in whole or in part, be used for any other purpose
without Digby Wells Environmental prior written consent.
Digby Wells Environmental
i
Aquatic Ecology
CDC2950
EXECUTIVE SUMMARY
Digby Wells Environmental was commissioned by Feronia PHC to conduct aquatic
ecological specialist studies on their Boteka oil palm concession, located within the central
Congo basin. The aim of this study was to establish the conservation value of the aquatic
ecosystems associated with the oil palm concession. As such, this study aims to establish
the ecological status, degree of endemism, conservation status of species and overall
conservation value of the associated river courses.
The river systems associated with the Boteka concession were found to be in an unmodified
state with instream and riparian habitats that were natural.
A total of 43 different fish species were captured during the February 2015 survey which
included 5 endemic species. The majority of the sampled species were found to be classified
as “Least Concern” (40) with 4 “not evaluated” and 1 “data deficient” classification. An
endemic assessment revealed a total of 30 endemic taxa expected to be present in the
Boteka concession. Of the total expected endemic taxa, 28 are of “least concern” with 2
species “data deficient”. No Rare, Threatened or Endangered species were captured or
expected within the Boteka oil palm concession.
The presence of several endemic taxa resulted in the classification of the river systems
considered as highly endemic. Furthermore, the presence of an abundance of juvenile fish
species in the larger Western and Loleka Rivers provides an indication that the rivers are
important nursery areas.
Recommendations have been made to study further the smaller tributaries considered in this
study as well as confirm the nursery function of the larger Western and Loleka Rivers.
Additionally, it was found that, the current planting regime on the Boteka oil palm concession
is adequate to allow for the presence of an effective buffer zone which has reduced the
potential for aquatic ecological impacts by the agricultural activity.
ii
Aquatic Ecology
CDC2950
TABLE OF CONTENTS
1
Introduction ....................................................................................................................... 1
1.1
2
Expertise of the Aquatic Specialist .......................................................................... 1
Methodology...................................................................................................................... 1
2.1
Surveys ................................................................................................................... 1
2.2
Water Quality .......................................................................................................... 2
2.3
Aquatic Habitat ........................................................................................................ 2
2.3.1
2.4
Fish ......................................................................................................................... 5
2.4.1
3
Intermediate Habitat Integrity Assessment........................................................ 2
Conservation Status and Expected Species ..................................................... 6
Study Sites, General Aquatic Habitat and Expected Diversity .......................................... 6
3.1
General Aquatic Habitat and Expected Diversity ..................................................... 6
3.2
Aquatic Habitat of the Boteka Concession ............................................................... 8
4
Results ............................................................................................................................ 13
4.1
Water quality ......................................................................................................... 14
4.2
Intermediate Habitat Assessment Index ................................................................ 14
4.2.1
Fish community assessment .......................................................................... 16
4.2.2
Endemic and Conservation Assessment ........................................................ 30
5
Discussion ....................................................................................................................... 31
5.1
Water quality ......................................................................................................... 31
5.2
Intermediate Habitat Integrity Assessment ............................................................ 32
5.3
Fish ....................................................................................................................... 34
5.3.1
Fish Community Assessment ......................................................................... 34
5.3.2
Endemic and Conservation Status Assessment ............................................. 35
6
Recommendations .......................................................................................................... 36
7
High Conservation Value related aspects ....................................................................... 36
8
Conclusions..................................................................................................................... 38
9
References ...................................................................................................................... 39
iii
Aquatic Ecology
CDC2950
LIST OF FIGURES
Figure 3-1: Freshwater fish species richness of the various Freshwater Ecoregions of the
world (Abel et al. 2008). ........................................................................................................ 7
Figure 3-2: Endemic freshwater fish species richness of the various Freshwater Ecoregions
of the world (Abel et al. 2008). .............................................................................................. 7
Figure 3-3: Location of the aquatic sampling points for the Boteka aquatic survey (February
2015). ................................................................................................................................... 9
Figure 3-4: Thick detritus substrate observed in the smaller tributaries (BOT5, February
2015). ................................................................................................................................. 10
Figure 3-5: Extensive lily pads (Nymphaea sp.) observed in the Loleka River (February
2015). ................................................................................................................................. 11
Figure 3-6: Floodplains observed in the Western River (February 2015). ............................ 11
Figure 5-1: Barriers present on the Boteka concession (February 2015). ............................ 32
Figure 5-2: Man-made burrows, Boteka concession (February 2015). ................................ 33
Figure 5-3: Nets left permanently in the rivers, Boteka concession (February 2015). .......... 34
Figure 5-4: Small-mesh seine net used to catch juvenile/small fishes (February 2015) ....... 34
LIST OF TABLES
Table 2-1: Criteria in the Assessment of Habitat Integrity (Kleynhans, 1996). ....................... 2
Table 2-2: Table giving descriptive classes for the assessment of modifications to habitat
integrity (Kleynhans, 1996).................................................................................................... 3
Table 2-3: Criteria and weights used for the assessment of habitat integrity (Kleynhans,
1996). ................................................................................................................................... 4
Table 2-4: Intermediate habitat integrity assessment categories (Kleynhans, 1996). ............ 5
Table 3-1: Global Positioning System (GPS) co-ordinates for the aquatic sampling points of
the Boteka oil palm concession (February 2015 survey). .................................................... 10
Table 3-2: General habitat photographs at each site during the February 2015 survey. ...... 12
Table 4-1: In situ water quality results obtained during the February 2015 survey for the
Boteka concession. ............................................................................................................. 14
Table 4-2: The instream assessment for the Western River. ............................................... 14
iv
Aquatic Ecology
CDC2950
Table 4-3: The riparian assessment for the Western River. ................................................. 15
Table 4-4: The instream assessment for the Loleka River. .................................................. 15
Table 4-5: The riparian assessment for the Loleka River. ................................................... 16
Table 4-6: Sampling effort, taxa sampled and Margalef’s richness index results obtained
during the February 2015 survey......................................................................................... 17
Table 4-7: Photographs and conservation status of Captured Fish (February, 2015): {Not
Evaluated (NE), Least Concern (LC), Data Deficient (DD)}. ................................................ 20
Table 4-8: Endemic taxa, their conservation status and distribution expected on the Boteka
concession. ......................................................................................................................... 30
Table 7-1: High Conservation Values for freshwater systems (Brown et al., 2013).............. 37
LIST OF APPENDICES
Appendix A: Fish community assessment
v
Aquatic Ecology
CDC2950
1
Introduction
The Feronia PHC (Feronia) business includes the restoration and operation of three Oil
Palm concessions on the Congo River and its associated tributaries: in Lokutu (Orientale
province), and Yaligimba and Boteka in Equateur Province. Feronia targets a RSPO
(Roundtable on Sustainable Palm Oil) certification for its three concessions. Digby Wells
Environmental (hereafter Digby Wells) was commissioned by Feronia to conduct aquatic
ecological specialist studies on their Boteka oil palm concession in the central Congo basin,
as part of an environmental assessment. The Congo River has the second greatest
discharge of any river in the world (the Amazon River has the largest), with the central
Congo basin being host to swamps and wetlands estimated to cover at least 120,000 km2.
There is a generally poor scientific understanding of the aquatic ecology due to poor
infrastructure, as well as socio-economic factors such as political instability and social unrest
(Campbell, 2005). Based on observations made by Digby Wells, it is clear that the health of
the aquatic ecosystems is currently threatened by activities which are causing loss of habitat
and, therefore, aquatic biodiversity.
The aim of this study was to establish the conservation value of the aquatic ecosystems
associated with the oil palm concession. The assessment enabled the baseline condition of
the rivers to be established and therefore, the current conservation status of the aquatic
ecosystems. The objective of the study was to establish the current ecological status, degree
of endemism, conservation status of species and overall conservation value of the river
courses.
This study forms a component of the overall biodiversity assessment incorporated into the
High Conservation Value (HCV) assessment for the Boteka concession.
1.1
Expertise of the Aquatic Specialist
Russell Tate is an aquatic ecologist in the Biophysical Department of Digby Wells, he is a
Professional Natural Scientist who holds a Master’s degree in aquatic health from the
University of Johannesburg (South Africa). Russell has published multiple scientific papers
and has completed aquatic assessments in several African countries including Botswana,
Democratic Republic of Congo (DRC), Mali, Senegal, Ivory Coast, South Africa, and
Mozambique. He has carried out focused tropical assessments in Cameroon, Liberia and
Ghana.
2
Methodology
For ease of reading the methodology has been divided into subsections which deal with
specific components.
2.1
Surveys
A single survey was completed at the Boteka concession from the 6th to the 13th February
2015. This coincides with the lower flow period in DRC. The rationale for surveying at this
1
Aquatic Ecology
CDC2950
time of year is that the river systems on the Boteka concession would be flowing adequately
(not flooding) which allows for effectively undertaking a biological assessment.
2.2
Water Quality
Water quality was measured using a calibrated Extech DO 700 multimeter. In situ
constituents considered in this study included temperature (ºC), pH, dissolved oxygen (mg/l)
and conductivity (µS/cm).
2.3
Aquatic Habitat
The availability and diversity of habitat is important to consider in assessments due to the
reliance and adaptations of aquatic biota to specific habitats (Barbour et al., 1996). Habitat
quality and availability assessments are usually conducted alongside biological assessments
that utilise fish and macroinvertebrates. Aquatic habitat (habitat) was assessed through
observations on each river system considered. The methods used for the assessment are
set out by Bain and Stevenson (1990), Vannote et al., (1980), and Gerber and Gabriel
(2002).
The assessment and description of habitat in this study has been used to ascertain the
potential presence of HCV/Rare, Threatened and Endangered (RTE) taxa. Furthermore, in
order to determine the conservation value of the considered river systems, an assessment
for the potential of “natural conditions” was completed (Brown et al., 2013).
2.3.1 Intermediate Habitat Integrity Assessment
In order to define a general habitat, for baseline purposes, the instream and riparian habitat
was assessed and characterised according to “Procedure for Rapid Determination of
Resource Directed Measures for River Ecosystems (Section D), 1999”.
The Intermediate Habitat Integrity Assessment (IHIA) model was used to assess the integrity
of the habitats from a riparian and instream perspective. The habitat integrity of a river refers
to the maintenance of a balanced composition of physico-chemical and habitat
characteristics on a temporal and spatial scale that are comparable to the characteristics of
natural habitats of the region (Kleynhans, 1996). The criteria utilised in the assessment of
habitat integrity in the current study are presented in Table 2-1.
Table 2-1: Criteria in the Assessment of Habitat Integrity (Kleynhans, 1996).
Criterion
Relevance
Water
abstraction
Direct impact on habitat type, abundance and size. Also implicated in flow, bed,
channel and water quality characteristics. Riparian vegetation may be influenced
by a decrease in the supply of water.
Flow
modification
Consequence of abstraction or regulation by impoundments. Changes in temporal
and spatial characteristics of flow can have an impact on habitat attributes such as
an increase in duration of low flow season, resulting in low availability of certain
2
Aquatic Ecology
CDC2950
Criterion
Relevance
habitat types or water at the start of the breeding, flowering or growing season.
Bed
modification
Regarded as the result of increased input of sediment from the catchment or a
decrease in the ability of the river to transport sediment (Gordon et al., 1993).
Indirect indications of sedimentation are stream bank and catchment erosion.
Purposeful alteration of the stream bed, e.g. the removal of rapids for navigation
(Hilden & Rapport, 1993) is also included.
Channel
modification
May be the result of a change in flow, which may alter channel characteristics
causing a change in marginal instream and riparian habitat. Purposeful channel
modification to improve drainage is also included.
Water quality
modification
Originates from point and diffuse point sources. Measured directly, or alternatively
indicated by human settlements, agricultural and industrial activities. Aggravated
by a decrease in the volume of water during low or no flow conditions.
Inundation
Destruction of riffle, rapid and riparian zone habitat. Obstruction to the movement
of aquatic fauna and influences water quality and the movement of sediments
(Gordon et al., 1992).
Exotic
macrophytes
Alteration of habitat by obstruction of flow and may influence water quality.
Dependent upon the species involved and scale of infestation.
Exotic aquatic
fauna
The disturbance of the stream bottom during feeding may influence the water
quality and increase turbidity. Dependent upon the species involved and their
abundance.
Solid waste
disposal
A direct anthropogenic impact which may alter habitat structurally. Also a general
indication of the misuse and mismanagement of the river.
Indigenous
vegetation
removal
Impairment of the buffer the vegetation forms to the movement of sediment and
other catchment runoff products into the river (Gordon et al., 1992). Refers to
physical removal for farming, firewood and overgrazing.
Exotic
vegetation
encroachment
Excludes natural vegetation due to vigorous growth, causing bank instability and
decreasing the buffering function of the riparian zone. Allochtonous organic matter
input will also be changed. Riparian zone habitat diversity is also reduced.
Bank erosion
Decrease in bank stability will cause sedimentation and possible collapse of the
river bank resulting in a loss or modification of both instream and riparian habitats.
Increased erosion can be the result of natural vegetation removal, overgrazing or
exotic vegetation encroachment.
The relevant criteria is then weighted and scored according to Kleynhans (1996), as seen in
the tables below (Table 2-2 and Table 2-3).
Table 2-2: Table giving descriptive classes for the assessment of modifications to
habitat integrity (Kleynhans, 1996).
3
Aquatic Ecology
CDC2950
Impact
Category
Description
Score
None
No discernible impact or the modification is located in such a way that
it has no impact on habitat quality, diversity, size and variability.
0
Small
The modification is limited to very few localities and the impact on
habitat quality, diversity, size and variability are also very small.
1-5
Moderate
The modifications are present at a small number of localities and the
impact on habitat quality, diversity, size and variability are also limited.
6-10
Large
The modification is generally present with a clearly detrimental impact
on habitat quality, diversity, size and variability. Large areas are,
however, not influenced.
11-15
Serious
The modification is frequently present and the habitat quality, diversity,
size and variability in almost the whole of the defined area are
affected. Only small areas are not influenced.
16-20
Critical
The modification is present overall with a high intensity. The habitat
quality, diversity, size and variability in almost the whole of the defined
section are influenced detrimentally.
21-25
Table 2-3: Criteria and weights used for the assessment of habitat integrity
(Kleynhans, 1996).
Instream Criteria
Weight
Riparian Zone Criteria
Weight
Water abstraction
14
Indigenous vegetation removal
13
Flow modification
13
Exotic vegetation encroachment
12
Bed modification
13
Bank erosion
14
Channel modification
13
12
Water quality
14
Water abstraction
13
Inundation
10
Inundation
11
Exotic macrophytes
9
Flow modification
12
Exotic fauna
8
Water quality
13
Solid waste disposal
6
TOTAL
100
TOTAL
100
Scores are then calculated based on ratings received from the assessment. The estimated
impacts of the criteria are then summed and expressed as a percentage to arrive at a
4
Aquatic Ecology
CDC2950
provisional habitat integrity assessment. The scores are then placed into the intermediate
habitat integrity assessment categories (Kleynhans, 1996) as seen in Table 2-4.
It should be noted that the IHIA was based on regions assessed in the current studies and
therefore may only constitute the assessment of conditions within a 50 km length of the
considered water courses.
Table 2-4: Intermediate habitat integrity assessment categories (Kleynhans, 1996).
Category
2.4
Description
Score
A
Unmodified, natural.
90-100
B
Largely natural with few modifications. A small change in natural
habitats and biota may have taken place but the ecosystem
functions are essentially unchanged.
80-90
C
Moderately modified. A loss and change of natural habitat and
biota have occurred but the basic ecosystem functions are still
predominantly unchanged.
60-79
D
Largely modified. A large loss of natural habitat, biota and basic
ecosystem functions has occurred.
40-59
E
The loss of natural habitat, biota and basic ecosystem functions
is extensive.
20-39
F
Modifications have reached a critical level and the lotic system
has been modified completely with an almost complete loss of
natural habitat and biota. In the worst instances the basic
ecosystem functions have been destroyed and the changes are
irreversible.
0-19
Fish
A variety of techniques were applied to sample fish species. The sampling methods
depended on site characteristics and included cast nets, fyke nets, gill nets, angling and
electro-fishing (Smith and Root LR-24).
A quantitative and qualitative fish assessment was completed. Fish community structures
and diversity were determined for each sampling site; this information was used to
investigate basic community characteristics. The information and specific characteristics of
dominant fish species, and the species occurring, allows for the analysis of the present
ecological state of the aquatic ecosystem.
The endemic and endangered species lists were compiled based on information from
Fishbase (www.fishbase.org) and Eschemeyer (2012). The range distribution of species was
taken from range maps of the International Union for Conserved Nature (IUCN) red list.
5
Aquatic Ecology
CDC2950
Identification of fish was completed using Paugy et al. (2003), Skelton (2001) and Verlag
(2004).
Furthermore,
photos
were
uploaded
to
the
Africhthy
website
(https://www.flickr.com/groups/africhthy) in order to solicit further identification of species.
2.4.1 Conservation Status and Expected Species
The conservation status of all captured fish species and those expected to be found during
the assessment was compared with reference to the following:
■ IUCN (IUCN) Red list of threatened species (IUCN);
■ Fishbase (www.fishbase.org); and
■ Eschmeyer (2012).
3
3.1
Study Sites, General Aquatic Habitat and Expected Diversity
General Aquatic Habitat and Expected Diversity
The focus area for this study was approximately 16 km east of the town Ingende, Equateur
province. The study considered tributaries of the Momboyo River. The Momboyo and
Tshuapa rivers flow into the Ruki River which is a tributary of the Congo River.
The study focus area is in the Cuvette Centrale freshwater Ecoregion (Thieme et al. 2005).
Based on available desktop information, the major aquatic habitat type in this region is
tropical/subtropical floodplain rivers with wetland complexes. The ecoregion has topography
that is almost totally flat, at about 300 m above sea level. The climate of the ecoregion is
characterised by an equatorial and wet climate with rainfall consistent almost year round.
According to Theime et al. (2005), the average annual rainfall in the ecoregion is between
1,500 mm and 2,000 mm with mean annual temperatures at 24 ºC.
The Cuvette Centrale freshwater ecoregion contains a variety of habitats which include:
open waters, small streams, coves, meadows of aquatic vegetation, permanent swamps and
extensive floodplains. In addition to physical habitats, floating Eichhornia masses are
associated with this ecoregion. Seasonally flooded riparian zones are associated with this
ecoregion which can result in permanent swamp forests with few dominant species but with
rich floral diversity.
According to Abel et al. (2008), the Cuvette Centrale freshwater ecoregion is host to a rich
fish fauna with approximately 300 fish species (Figure 3-1) and 12 (known) taxa that are
specifically endemic to the Cuvette Centrale freshwater ecoregion (Figure 3-2).
6
Aquatic Ecology
CDC2950
Figure 3-1: Freshwater fish species richness of the various Freshwater Ecoregions of
the world (Abel et al. 2008).
Figure 3-2: Endemic freshwater fish species richness of the various Freshwater
Ecoregions of the world (Abel et al. 2008).
7
Aquatic Ecology
CDC2950
It should be noted that although 300 taxa are expected to be present, only 240 species have
been documented in scientific journals. A recent study of fishes of the Salonga National Park
revealed the presence of 152 species within the immediate region (Iyaba and Stiassny,
2013).
In general, the Cuvette Centrale freshwater ecoregion is considered to have a limited
number of threatened taxa (Brooks et al. 2011). The main factor contributing to the low
number of threatened taxa is the remote locations of tributaries (undisturbed areas).
Furthermore, regional endemism is low due to the interconnected nature and historical
climatic shifts of the of the Cuvette Centrale freshwaters (Iyaba and Stiassny, 2013).
3.2
Aquatic Habitat of the Boteka Concession
A total of 6 sites were considered during the Boteka aquatic assessment (Figure 3-3 and
Table 3-1)), with the specific details provided below for future assessments. Due to the
timing the sites were selected in annual river systems and therefore non-perennial systems
were not considered.
8
Aquatic Ecology
CDC2950
Figure 3-3: Location of the aquatic sampling points for the Boteka aquatic survey
(February 2015).
9
Aquatic Ecology
CDC2950
Table 3-1: Global Positioning System (GPS) co-ordinates for the aquatic sampling
points of the Boteka oil palm concession (February 2015 survey).
Site
GPS co-ordinate
River
Western River
BOT1
-0.412968° 19.054632°
BOT4
-0.444996° 19.065845°
BOT5
-0.473760° 19.067043°
River
Loleka River
BOT2
-0.483893° 19.200348°
BOT3
-0.456719° 19.181370°
BOT6
-0.459870° 19.146510°
The sampling sites were selected on two separate tributaries of the Momboyo River; the
Loleka River is the largest of the tributaries. All sites were found to be dominated by swamp
habitats with limited flow and deep leafy detritus substrate (Figure 3-4).
Figure 3-4: Thick detritus substrate observed in the smaller tributaries (BOT5,
February 2015).
The dominant aquatic habitats in the smaller tributaries were swamp conditions presenting
abundant submerged root wads. In the larger tributaries different habitats types were
observed and are described in the following sections. Deep channels and extensive
10
Aquatic Ecology
CDC2950
floodplains allowed for the proliferation of large areas of lily pads (Nymphaea sp.) (Figure
3-5). In the larger river systems (±15–20m width), large areas submerged swamp vegetation
were observed. This habitat is likely flooded during the higher flow periods and will provide
important breeding habitats for various fish species (Figure 3-6). The water column of the
larger rivers was dark and tea coloured, which is attributed to the large amount of decaying
detritus and swamp-like conditions. Table 3-2 presents photographs that illustrated the
aquatic habitat for each study site (BOT1–BOT6); the biological assessment refers to each
of these.
Figure 3-5: Extensive lily pads (Nymphaea sp.) observed in the Loleka River (February
2015).
Figure 3-6: Floodplains observed in the Western River (February 2015).
11
Aquatic Ecology
CDC2950
Table 3-2: General habitat photographs at each site during the February 2015 survey.
Site
Photograph
General Habitat
BOT1
Swamp, Submerged
vegetation and sandy
substrate
BOT2
Swamp, Submerged
vegetation and sandy
substrate
BOT3
Sand, deep channels
with detritus
12
Aquatic Ecology
CDC2950
Site
4
Photograph
General Habitat
BOT4
Sand, deep detritus
and roots
BOT5
Sand, deep detritus
and roots
BOT6
Sand, deep detritus
and roots
Results
The results section has is presented in the same layout as the methodology section above.
13
Aquatic Ecology
CDC2950
4.1
Water quality
In situ water quality results from the February 2015 survey are presented in Table 4-1.
Table 4-1: In situ water quality results obtained during the February 2015 survey for
the Boteka concession.
Constituent
BOT1
BOT2
BOT3
BOT4
BOT5
BOT6
Temperature (ºC)
21
22
23
26
24
26
pH
4.2
4.5
4.1
4.6
4.8
4.8
Conductivity
(µS/cm)
28
37
35
27
30
19
Dissolved oxygen
(mg/l)
2.4
3.5
3.3
2.1
2.3
3.2
The results of the in situ analysis indicated that temperatures were consistent across the
sites; ranging from 21 ºC at BOT1 to 26 ºC at BOT4 and BOT6. The power of hydrogen (pH)
varied between 4.1 at BOT3 to 4.8 at BOT5 and BOT6. Dissolved solids, measured as
electrical conductivity (µS/cm) ranged from a low of 19 µS/cm at BOT6 to 37 µS/cm at
BOT2. Dissolved oxygen concentrations ranged from 2.1 mg/l at BOT4 to 3.5 mg/l BOT2.
4.2
Intermediate Habitat Assessment Index
The intermediate habitat assessment was carried out in the Western and Loleka Rivers. The
Western River included BOT1, BOT4 and BOT5; results are presented in Table 4-2 and
Table 4-3.
Table 4-2: The instream assessment for the Western River.
Instream
Average score
Score
Water abstraction
0
0
Flow modification
5
2.6
Bed modification
5
2.6
5
2.6
Water quality
1.6
0.9
Inundation
1.6
0.6
Exotic macrophytes
0
0
14
Aquatic Ecology
CDC2950
Instream
Average score
Score
Exotic fauna
0
0
0
0
Total Instream
90.6
Category
class A
Table 4-3: The riparian assessment for the Western River.
Riparian
Indigenous vegetation
removal
Exotic vegetation
encroachment
Average score
Score
5
2.6
1
0.48
Bank erosion
0
0
1.6
0.8
Water abstraction
0
0
Inundation
1.6
0.8
Flow modification
2.6
1.28
Water quality
1.6
0.86
Total Riparian
93.2
Category
class A
The results of the IHIA show that instream and riparian habitat of the Western River is
currently in an unmodified state (class A).
Sites included in the Loleka River IHIA were BOT2, BOT3 and BOT6. The results of the
assessment are presented in Table 4-4 and Table 4-5.
Table 4-4: The instream assessment for the Loleka River.
Instream
Average score
Score
Water abstraction
0.00
0.00
Flow modification
5.00
2.60
Bed modification
3.33
1.73
1.67
0.87
Water quality
0.00
0.00
15
Aquatic Ecology
CDC2950
Instream
Average score
Score
Inundation
1.67
0.67
Exotic macrophytes
0.00
0.00
Exotic fauna
0.00
0.00
0.00
0.00
Total Instream
94
Category
class A
Table 4-5: The riparian assessment for the Loleka River.
Riparian
Indigenous vegetation
removal
Exotic vegetation
encroachment
Average score
Score
1.67
0.8
1.67
0.8
Bank erosion
0.00
0
0.00
0
Water abstraction
0.00
0
Inundation
1.67
0.7
Flow modification
1.67
0.8
Water quality
0.00
0
Total Riparian
96.8
Category
class A
Considering the above results, it is clear that the instream and riparian habitat of the Loleka
River system is in an unmodified status (class A).
4.2.1 Fish community assessment
A total of 43 species were sampled during the February 2015 survey; results are presented
in Table 4-6.
16
Aquatic Ecology
CDC2950
Table 4-6: Sampling effort, taxa sampled and Margalef’s richness index results
obtained during the February 2015 survey.
Site
Effort
Species
Amount
Taxa
Individual
s
Margalefs
richness
index
Ctenopoma kingsleyae
Aplocheilichthys brichardi
Barbus holotaenia
Brycinus imberi
Ctenopoma gabonense
Hemichromis bimaculatus
BOT
1
Local
gill nets
Hemichromis elongatus
N/A
Hepsetus odoe
Hylopanchax cf. silvestris
Micralestes humilis
Papyrocranus congoensis
Petrocephalus cf. catostoma
Tilapia cf. tholloni
Alestes macrophthalmus
Brycinus bimaculatus
Bryconaethiops boulengeri
Charra obscura
Distichodus fasciolatus
BOT
2/3
Local
gill nets
Hepsetus odoe
Macrusenius sp.
N/A
Mormyrops anguilloides
Polypterus weeksii
Tilapia cf congica
Type 1.
17
Aquatic Ecology
CDC2950
Site
Effort
Species
Amount
Taxa
Individual
s
Margalefs
richness
index
13
62
2.9
11
79
2.2
12
117
2.3
Xenomystus nigri
BOT
28
4 Minutes
BOT
23
5 minutes
BOT
38
6 minutes
Xenomystus nigri
3
Aphyosemion cf. elegans
16
Barbus hulstaerti
6
Clarias theodorae
2
Epiplatys fasciatus
2
4
Microctenopoma ansorgii
4
Microctenopoma sp1
1
Nanochromis teugelsi
3
Neolebias trewavasae
18
Parauchenoglanis
ngamensis
Schilbe marmoratus
1
Tilapia cf. cabrae
1
Channallabes apus
3
5
Barbus holotaenia
4
Barbus hulstaerti
43
Congochromis dimidiatus
5
Ctenopoma multispine
1
Epiplatys fasciatus
1
Hepsetus odoe
1
6
9
Phractolaemus ansorgii
1
Channallabes apus
1
5
Barbus hulstaerti
62
1
18
Aquatic Ecology
CDC2950
Site
Effort
Species
Amount
Clarias theodorae
4
5
Epiplatys sp1.
1
Hepsetus odoe
5
6
Microctenopoma fasciolatum
4
8
15
Pantodon buchholzi
1
Taxa
Individual
s
Margalefs
richness
index
The results of the fish community assessment are provided in appendix A. The diversity of
fish ranged at the sites (selected for quantitative sampling) from 11 species at BOT5 to 13
species at BOT4. Total individuals captured at the sites ranged from 62 at BOT4 to 117 at
BOT6. The result of the Margalefs richness index showed ranges from 2.2 at BOT5 to 2.9 at
BOT4. Photographs and the conservation status of the captured fish are presented in the
table below (Table 4-7).
19
Aquatic Ecology
CDC2950
Table 4-7: Photographs and conservation status of Captured Fish (February, 2015):
{Not Evaluated (NE), Least Concern (LC), Data Deficient (DD)}.
Species
Photo
Ctenopoma kingsleyae
Native/Indigenous
LC
Ctenopoma gabonense
Native/Indigenous
NE
Microctenopoma nanum
Native/Indigenous
LC
Native/Indigenous
LC
20
Aquatic Ecology
CDC2950
Species
Photo
Native/Indigenous
LC
Microctenopoma
fasciolatum
Native/Indigenous
LC
Hemichromis bimaculatus
Native/Indigenous
LC
Tilapia cf. tholloni
Native/Indigenous
LC
21
Aquatic Ecology
CDC2950
Species
Photo
Tilapia cf congica
Native/Indigenous
LC
Tilapia cf. cabrae
Native/Indigenous
LC
Congochromis dimidiatus
Native/Indigenous
LC
22
Aquatic Ecology
CDC2950
Species
Photo
Native/Indigenous
LC
Petrocephalus cf.
catostoma
Native/Indigenous
NE
Marcusenius sp.
Native/Indigenous
NE
Mormyrops anguilloides
Native/Indigenous
LC
Xenomystus nigri
Native/Indigenous
LC
23
Aquatic Ecology
CDC2950
Species
Photo
Native/Indigenous
LC
Pantodon buchholzi
Native/Indigenous
LC
Polypterus weeksii
Native/Indigenous
LC
Parauchenoglanis
ngamensis
Native/Indigenous
LC
Native/Indigenous
LC
24
Aquatic Ecology
CDC2950
Species
Photo
Channallabes apus
Native/Indigenous
LC
Clarias theodorae
Native/Indigenous
LC
Charra obscura
Native/Indigenous
LC
Schilbe marmoratus
Native/Indigenous
LC
Epiplatys sp1.
N/A
N/A
25
Aquatic Ecology
CDC2950
Species
Photo
Epiplatys fasciatus
Native/Indigenous
NE
Aphyosemion elegans
Native/Indigenous
LC
Neolebias trilineatus
Endemic
LC
Native/Indigenous
LC
26
Aquatic Ecology
CDC2950
Species
Photo
Hylopanchax cf. silvestris
Endemic
NE
Endemic
LC
Barbus holotaenia
Native/Indigenous
LC
Barbus hulstaerti
Endemic
LC
27
Aquatic Ecology
CDC2950
Species
Photo
Type 1.
Native/Indigenous
LC
Native/Indigenous
LC
Hepsetus odoe
Native/Indigenous
LC
Endemic
LC
28
Aquatic Ecology
CDC2950
Species
Photo
Brycinus imberi
Native/Indigenous
LC
Micralestes humilis
Native/Indigenous
LC
Bryconaethiops boulengeri
Native
LC
Alestes macrophthalmus
Native/Indigenous
LC
Native
LC
29
Aquatic Ecology
CDC2950
A total of 43 species were captured during the assessment. Five endemic species were
captured. The majority of the sampled species were classified as “Least Concern” (40) with 4
“not evaluated” and 1 “data deficient” classification (IUCN, 2015).
4.2.2 Endemic and Conservation Assessment
The results of the assessment for potential endemic species are presented in Table 4-8.
Table 4-8: Endemic taxa, their conservation status and distribution expected on the
Boteka concession.
Species
Conservation Status
Distribution
LC
Regional
Barbus hulstaerti
Barbus matthesi
Clariallabes centralis
Congocharax olbrechtsi
Ctenopoma weeksii
LC
LC
LC
LC
LC
LC
Regional
Regional
National
Regional
Regional
National
Distichodus decemmaculatus
LC
Regional
Dolichallabes microphthalmus
LC
Regional
Hemistichodus lootensi
LC
Regional
Hemistichodus mesmaekersi
LC
Regional
Marcusenius ghesquierei
LC
Regional
Marcusenius kutuensis
Micralestes congicus
LC
LC
Regional
Regional
Microstomatichthyoborus bashforddeani
LC
National
Nannothrissa parva
Neolebias gracilis
Neolebias trilineatus
Paradoxoglanis parvus
LC
DD
LC
LC
Regional
Local
National
National
Phenacogrammus deheyni
LC
Regional
Phenacogrammus interruptus
LC
National
Phenacogrammus polli
Phractura lindica
Pollimyrus schreyeni
LC
LC
LC
Regional
National
Regional
30
Aquatic Ecology
CDC2950
Species
Conservation Status
Distribution
Stomatorhinus fuliginosus
LC
Regional
Stomatorhinus patrizii
Synodontis aterrimus
LC
LC
Regional
Regional
Synodontis camelopardalis
DD
Regional
Tricuspidalestes caeruleus
LC
Regional
Tylochromis aristoma
LC
Regional
Least Concern (LC) and Data Deficient (DD). National labels refer to the distribution range
lying over the upper, middle or lower Congo basin. Regional labels refer to the taxa being
defined to the middle and/or upper Congo basin.
Based on the results of the endemic assessment completed by Digby Wells, a total of 30
endemic taxa are expected to be present in the Boteka concession. According to the IUCN
Red list, 28 of the expected taxa are considered to be of “least concern” with 2 species “data
deficient”. When considering the total list of endangered taxa in the DRC, no RTE taxa are
expected to be present on the Boteka concession.
5
Discussion
For ease of understanding and navigation the discussion has been divided as per the
methodology and results sections above.
5.1
Water quality
In summary, water quality analyses are as follows:
■ The water temperature of the rivers in the Boteka concession averaged around 23ºC.
These are natural temperatures when considering the habitat type is tropical streams.
■ The pH was found to be relatively consistent within the rivers of the Boteka
concession. The majority of the sites had slightly acidic pH levels (4-5).
The acidic nature of the sites are likely due to the decomposition of allochthonous
material and seepage of plant derived acids/tannins and other chemicals from
decaying leafy material, these pH levels are therefore seen as natural (Deano and
Robinson, 1985).
■ Dissolved solids, measured as conductivity, were in notably low concentrations on the
Boteka concession with the highest levels recorded at BOT2. These low
concentrations show that anthropogenic activities on the concession do not contribute
a large amount of solutes to the local river systems. In addition, these low dissolved
solid concentrations indicate the large degree of dilution capacity available in these
local river systems and illustrate typical and natural tropical conditions (Balek, 1983).
31
Aquatic Ecology
CDC2950
■ Dissolved oxygen concentrations were low which is typical of low gradient swampy
habitats. These low concentrations are a result of the reducing environment, caused
by the removal of oxygen by decaying organic matter and are, therefore, viewed as
natural.
In conclusion, water quality results illustrate conditions which would be expected when
assessing a tropical river system.
5.2
Intermediate Habitat Integrity Assessment
The integrity of aquatic habitats has a direct impact on the aquatic biota (certain species are
more sensitive than others). When considering the results obtained for the IHIA for the
Western River system, modification was found to be “uncommon” in terms of the habitat
model.
Man-made barriers (Figure 5-1) and burrows (Figure 5-2) were found near villages on the
Boteka concession; it is assumed such barriers are only near villages and so have a little
impact. The barriers and burrows are used to attract larger fishes which are captured using
hooks and lines, or gill nets. These instream impacts are viewed as temporary as they are
washed away in heavy rain.
Figure 5-1: Barriers present on the Boteka concession (February 2015).
Communities use the rivers for bathing and general washing (laundry and cooking utensils)
which has caused deterioration of water quality. However, this has been assessed as having
a small impact because contamination is diluted and sediments are disturbed but settle
downstream.
The overall status of the instream habitat of the Western River was found to be unmodified
(class A); anthropogenic impacts in the river system are infrequent.
32
Aquatic Ecology
CDC2950
Figure 5-2: Man-made burrows, Boteka concession (February 2015).
The riparian habitat assessment for the Western River showed it was in natural state (class
A).
Removal of indigenous vegetation in the buffer zone of tributaries was assessed as having a
small impact in the Western River riparian habitat. It was concluded the impact was small
due to riparian areas being remote and inaccessible.
In conclusion, the habitat of the Western River was natural with isolated impacts attributed to
activities such as barriers, washing and fishing are all small impacts.
The Loleka River instream habitat assessment had similar results to that of the Western
River:
■ The presence of infrequent and small impacts resulted in the unmodified classification
(class A).
■ The riparian habitat of the Loleka River is unmodified (class A) with no discernible
impacts to the riparian conditions of the river system.
Fishing and associated activities are placing pressure on local fish resources (e.g. gill nets
are left in many places (Figure 5-3)). Furthermore, local fishing techniques include small
mesh seine nets which are used to capture the abundant small fish (Figure 5-4). These small
fish are predominantly juvenile fish or fry which are using cover, created by the swamp, as a
nursery. It is unlikely that the fishing impacts would have a negative impact on aquatic
habitat, but the impact on local fish communities would be large.
33
Aquatic Ecology
CDC2950
Figure 5-3: Nets left permanently in the rivers, Boteka concession (February 2015).
Figure 5-4: Small-mesh seine net used to catch juvenile/small fishes (February 2015)
5.3
Fish
5.3.1 Fish Community Assessment
Ichthyological surveys in the Congo River basin have mostly focused on the main stems of
the large river systems. Therefore, there is very little information on the fish communities of
smaller tributaries (Brooks et al. 2011). Thus, this study and the description of the
community structures in small tributaries provide important baseline information for
management, monitoring and conservation.
The most abundant fish captured was the endemic species Barbus hulstaerti with 111
individuals captured during the survey. This small Barb inhabits shallow rainforest streams
and swamps with dense marginal vegetation. During electrofishing the species was
34
Aquatic Ecology
CDC2950
encountered as large shoals which were under the ample submerged vegetation. The
species is classified as least concern due to its wide distribution and lack of major threats.
The second most abundant species captured was Neolebias trewavasae. This distichodontid
fish is known to occur in central Africa and has a wide distribution. This species was
electrofished in the small impoundments created by the local people; the fish were in shoals
along with Barbus hulstaerti.
The third-most abundant species sampled was Aphyosemion cf. elegans. This species
prefers shallow rainforest streams with full cover and submerged vegetation. The species
was sampled in abundance in the small streams throughout the Boteka concession. The
species is considered to be an indicator of riparian integrity due to its reliance on the
rainforest canopy for cover (Toham and Teugels, 1999). The conservation status of the
species is least concern due to its wide distribution and lack of serious threats.
When the dominant taxa are compared to a recent study completed in several larger rivers
upstream of the study area, clear differences are noted (Inogwabini, 2005). Dominant taxa in
the study consisted of small fishes with adaptations to shallow swamps and full canopy
cover whereas dominant taxa in the study by Inogwabini (2005) comprised taxa adapted to
deeper waters (Synodontis and Auchenoglianus).
The dominance of species adapted to rainforest (full cover) conditions illustrates the largely
natural status of the riparian zones in the Boteka concession. Thus, it is apparent that the
current management measures, in terms of the layout of oil palms, are sufficient to support
buffer zones of riparian habitat. These intact buffer zones reduce potential impacts on water
quality and sedimentation on the main reaches of the rivers within the Boteka concessions.
The highest diversity of fishes was observed at BOT4 and, based on the community
structure, the site also received the highest richness score. The increased diversity at the
site is thought to be a result of the variety of habitat created through man-made burrows
which is the ideal habitat for species such as Xenomystus nigri and Schilbe marmoratus
which prefer darker and deeper habitats, respectively.
At BOT5 and BOT6, the predatory Hepsetus odoe was captured illustrating the overall
complete nature of the fish communities on the Boteka concession. In addition, an
interesting species Phractolaemus ansorgii was captured during the survey; it is adapted to
low oxygen habitats and supports the in situ oxygen water quality data findings.
During the survey an abundance of juvenile fish were observed in the larger river systems,
including the Western and Loleka Rivers. The presence of these juveniles indicates that the
tributaries are nursery areas and are of great importance.
5.3.2 Endemic and Conservation Status Assessment
The assessment of potential endemic fish in the Boteka concession revealed that 30
endemic taxa may be present. Five of these were confirmed by Digby Wells. The majority of
the endemic species captured are small species specialised and adapted to rainforest
conditions. In addition to the five endemic taxa, an additional four species are possibly
35
Aquatic Ecology
CDC2950
restricted to the Ruki River. However, due to the large area of the Ruki River, the endemic
species are still considered to be regionally endemic by Digby Wells.
The majority of the expected endemic taxa are regionally endemic and have a “least
concern” conservation status. The central cause for the regional endemism can be linked to
the interconnected nature of the central Congo basin. It is a result of “repeated climatic shifts
resulting in fluctuating forest contraction and expansion since the Middle Pleistocene” (Iyaba
and Stiassny, 2013).
Threats to fish species within the Middle Congo River basin are few because of the
inaccessible nature of the flooded wetlands and forests. However, according to Brooks et al.
(2011) in the early 1990s, 37% of the total exploitable rainforest had been designated as
timber concessions. Thus forestry and associated sedimentation could present a limiting
factor and potential threat to fish species in the future. Further threats to fish species in the
Middle Congo River include extensive fishing as observed during this study.
Although threats to the fish species are currently increasing, due to the wide distributions
and high levels of interconnectivity between the various freshwater regions in the Congo
River basin, the effect of these potentially threatening activities on a larger scale (during the
present-day) do not present serious threats to the fish communities in the Ruki River
drainage.
Overall it was found by Digby Wells that the fish in the river systems in the Boteka
concession are regarded as endemic and the larger Western and Loleka Rivers are
important nursery areas.
6
Recommendations
Based on the results of this study the following recommendations can be made:
■ Future studies should focus on the smaller tributaries on the Boteka Concession.
Furthermore, the nursery status of the larger rivers associated with the concession
should be investigated further.
■ Migratory and temporal use of the rivers in the Boteka concession by aquatic ecology
should be investigated further and the nursery status of the larger rivers confirmed.
■ The current activities by local communities have had limited effects on the ecological
status of the rivers on the Boteka concession. Excessive netting with small mesh
sizes was also observed. It is recommended that future studies assess the impacts of
these activities.
■ The current riparian buffer zones in place between the oil palm plantations and the
local river systems should be maintained.
7
High Conservation Value related aspects
The guidelines listed in Brown et al. (2013) were used to derive Table 7-1. It should be noted
that the table has only been populated based on the preliminary findings of this report;
detailed information is presented in the HCV report (Digby Wells, 20151).
36
Aquatic Ecology
CDC2950
Table 7-1: High Conservation Values for freshwater systems (Brown et al., 2013).
HCV1
Present/absent
Rationality
Presence of RTE species
Absent
Not found to be present
in studies
Presence of protected areas
for RTE taxa
Absent
Not within study focus
area
Presence of endemic, highly
range limited species
Absent
Wide range of endemic
species
Critical dispersal routes for
fish
Absent
Not major river systems
HCV2
Present/absent
Rationality
Rivers with natural flow
regimes
Present
Unmodified systems
Rivers without downstream
and upstream barriers
Present
Unmodified systems
Unmodified river channels
Present
Unmodified systems
Unmodified thermal,
sediment and nutrient
regimes
Present
Unmodified systems
Land cover conversion below
threshold of concern
Not considered
Not considered
Rivers without invasive taxa
Possible
Invasive taxa not
observed
HCV3
Present/absent
Rationality
Rare, threatened or
endangered freshwater
ecosystems
Absent
Not unique or rare
HCV4
Present/absent
Rationality
Floodplains and wetlands
Present
Floodplains present
37
Aquatic Ecology
CDC2950
Riparian forests
Present
Observed on site
Unleveed floodplains
Present
Observed on site
Areas with a critical
recharging effect on aquifers
used for potable water
Absent
Not observed
High surface water yield
areas
Present
Not unique/uncommon
Vegetated areas upstream of
critical water supplies
Present
Not unique/uncommon
HCV5
Present/absent
Rationality
Water sources necessary for
access to basic drinking
water and sanitation
Present
Observed on site
Freshwater animal
populations relied upon by
local communities
Present
Observed on site
HCV6
Present/absent
Rationality
Water bodies of high religious
or cultural significance
Digby Wells, 20152
Digby Wells, 20152
Freshwater products with
cultural values
Digby Wells, 20152
Digby Wells, 20152
8
Conclusions
The conclusions to the studies are:
■ The assessment of aquatic ecological conditions in the rivers associated with the
Boteka concession revealed the systems are unmodified and near natural condition.
■ Biological assessments revealed a largely intact riparian zone in the rivers
considered.
■
There is sufficient buffer capacity between oil palm plantations and the considered
river systems to promote and maintain typical tropical riparian habitats which will allow
for the proliferation of natural species.
■ The assessment for RTE ichthyofaunal taxa revealed the general absence of
endangered fish species in the Boteka concession.
38
Aquatic Ecology
CDC2950
■ The assessment for endemic fish taxa revealed that endemic taxa would be expected
and confirmed the high level of endemism on the Boteka concession.
■ Further assessment by Digby Wells revealed that the endemic taxa expected and
confirmed to be present, have wide distributions and are considered least concern in
terms of conservation statuses.
9
References
Abel R, Thieme ML, Revenga C, Bryer M, Kottelat M, Bogutskaya N, Coad B, Mandrak N,
Contreras Balderas S, Biussing W, Stiassny MLJ, Skelton P, Allen GR, Unmack P, Naseka
A, Ng R, Sindorf N, Robertson J, Armijo E, Higgins JV, Heibel TJ, Wikramanayake E, Olson
D, Lopez HL, Reis RE, Lundberg JG, Mark H, Perez S, Petry P. 2008. Freshwater
Ecoregions of the World: A new map for biogeographic units for freshwater biodiversity
conservation. Bioscience. 58:403–414.
Bain MB, Stevenson N. 1999. Aquatic habitat assessment: Common methods, American
Fisheries Society, Bethesda, Maryland.
Balek J. 1983. Hydrology and water resources in tropical regions. Elsevier Science.
Amsterdam, Netherlands.
Barbour MT, Gerritsen J, White JS. 1996. Development of a stream condition index (SCI) for
Florida. Florida Department of Environmental Protection: Tallahassee, Florida.
Brooks EGE, Allen DJ, Darwall WRT. 2011. The status and distribution of freshwater
biodiversity in central Africa. IUCN. Cambridge. United Kingdom.
Brown E, Dudley N, Lindhe A, Muhtanian DR, Stewart C, Synnott T. 2013. Common
guidance for the identification of High Conservation Values. HCV Resource Network.
Campbell D. 2005. The World’s Largest Wetlands: Ecology and Conservation. Cambridge
University Press.
Deano PM, Robinson JW. 1985. The effect of decaying leaves on the pH and buffer capacity
of water. Journal of Environmental Science and Health. 20: 903–911.
Digby Wells Environmental 1. 2015 High Conservation Value Assessment, Lokutu Oil Palm
Concession, CDC2950.
Digby Wells Environmental2. 2015. Social Assessment for Feronia PHC’s Oil Palm
Plantations in the Democratic Republic of Congo, Stakeholder Engagement Plan. CDC2950.
Eschmeyer, WN. 2012. Catalog of Fishes. Electronic database accessible at
http://research.calacademy.org/ichthyology/catalog/fishcatmain. asp accessed May 2015.
Fishbase. 2015. Available at: http://www.fishbase.org/. Accessed 2015/04/14.
Gerber A, Gabriel MJM. 2002. Aquatic Invertebrates of South African Rivers: Field Guide.
Institute for Water Quality Services, Department of Water Affairs and Forestry, Pretoria.
Hellawell K. 1977. Biological surveillance and water quality monitoring. Biological monitoring
of inland fisheries. 69–88.
39
Aquatic Ecology
CDC2950
Inogwabini BI. 2005. Fishes of the Salonga National Park, Democratic Republic of Congo:
Survey and conservation issues. Orxy, 39: 78–81.
IUCN. 2015. Available at http://www.iucnredlist.org/details/181572/0. Accessed 2015/04/14.
Iyaba RJCM, Stiassny MLJ. 2013. Fishes of the Salonga National Park (Congo basin,
central Africa)): A list of species collected in the Luilaka, Salonga, and Yenge Rivers
(Equateur Province, Democratic Republic of Congo). Checklist 9: 246–256.
Kleynhans CJ. 1996 A qualitative procedure for the assessment of the habitat integrity status
of the Luvuvhu River. Journal of Aquatic Ecosystem Health 5: 41–54.
Margalef R. 1961. Information Theory in Ecology. General Systems 3: 36–71.
McMillan PH, 1998. An integrated habitat assessment system (IHAS v2) for the rapid
biological assessment of rivers and streams. Division of the Environment and Forestry
Technology, Report No. ENV-P-`I 98132. CSIR, Pretoria.
Palmer RW, Taylor ED. 2004. The Namibian Scoring System (NASS) version 2 rapid bioassessment method for rivers. African journal of aquatic science. 29: 229–234.
Paugy D, Leveque C, Teugels GG, Bigorne R, Romand R. 1990. Freshwater fishes of Sierra
Leone and Liberia: Annotated checklist and distribution. Revision Hydrobiology tropical. 23:
329–350.
Rowntree KM, Ziervogel G. 1999. Development of an index of stream geomorphology for the
assessment of river health. National Aquatic Ecosystem Biomonitoring Programme. Report
Series No.7.
Skelton PH. 2001. A Complete Guide to the Freshwater Fishes of Southern Africa. Struik
Publishers, Cape Town, South Africa.
Thieme ML, Abell R, Stiassny MLJ, Skelton P. 2005. Freshwater Ecoregions of Africa and
Madagascar: A Conservation Assessment. World Wildlife Fund.
Toham AK, Teugels GG. 1999. First data on an Index of Biotic Integrity (IBI) based on fish
assemblages for the assessment of the impact of deforestation in a tropical West African
river system. Hydrobiologia. 397: 29–38.
United States Environmental Protection Agency. 2006. Wadeable streams assessment: A
collaborative survey of the nation’s streams. EPA/841/B-06/002.
Vannote RL, Minshall GW, Cummins KW, Sedell JR Cushing CE. 1980. The River
Continuum Concept. Canadian Journal of fisheries and Aquatic Science. 37: 130–137.
Verlag BS. 2004.The Cichlid Fishes of Western Africa. First edition. Germany.
40
Aquatic Ecology
CDC2950
Appendix A: Fish community assessment
Aquatic Ecology
Aquatic Assessment at Boteka
CDC2950
Taxa
Xenomystus nigri
Barbus hulstaerti
Clarias theodorae
Epiplatys fasciatus
Hemichromis fasciatus
Microctenopoma sp1
Nanochromis squamiceps
Neolebias gracilis
Parauchenoglanis ngamensis
Schilbe cf. uranoscopus
Figure 1-1: BOT4 fish community assessment.
Taxa
Channallabes apus
Barbus holotaenia
Barbus hulstaerti
Chromidotilapia cf. schoutedeni
Epiplatys fasciatus
Hepsetus odoe
Nanochromis squamiceps
2
Aquatic Ecology
Aquatic Assessment at Boteka
CDC2950
Taxa
Channallabes apus
Barbus hulstaerti
Clarias theodorae
Epiplatys fasciatus
Epiplatys sp1.
Hepsetus odoe
Microctenopoma fasciolatum
Nanochromis cf. squamiceps
Neolebias gracilis
Pantodon buchholzi
3

Aquatic Ecology Assessment at Boteka Aquatic Ecology

Transcription

Similar documents

Camp Manitoqua Aquatic Center - Iprm Construction Management

Springbank Aquatic Center - Iprm Construction Management In

Star Wars Aquatic Special Event

Issue 3 - June 7, 2008

10 species of sea anemones

To this: Davidsonville Wildlife Sanctuary Wetland Restoration Best

Therapy Times - Performance Rehabilitation

VihtaVuori

Long Island Aquatic Club

Red-eared sliders and yellow-bellied sliders are semi