Biodiversity Data Journal :
Research Article
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Corresponding author: Johan Ismail (ijohan@upm.edu.my)
Academic editor: Dimitris Poursanidis
Received: 16 Apr 2021 | Accepted: 01 May 2021 | Published: 17 Jun 2021
© 2021 Johan Ismail, Abu Hena Mustafa Kamal, Mohd Hanafi Idris, S. M. Nurul Amin, Hadi Hamli, Leong Sui Sien, Abdulla Al-Asif, Muyassar Abualreesh
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Ismail J, Mustafa Kamal AH, Idris MH, Amin SMN, Hamli H, Sien LS, Al-Asif A, Abualreesh MH (2021) Zooplankton species composition and diversity in the seagrass habitat of Lawas, Sarawak, Malaysia. Biodiversity Data Journal 9: e67449. https://doi.org/10.3897/BDJ.9.e67449
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Seagrass habitats are considered to be some of the most biodiverse ecosystems on the planet and safeguard some ecologically and economically important fauna, amongst which are some globally threatened species, including dugong. Malaysian seagrass ecosystems are not widespread, but their existence supports some significant marine fauna. A rigorous zooplankton study was conducted from May 2016 to February 2017, in the seagrass habitat of Lawas, Sarawak, Malaysia, to examine their temporal composition and diversity, together with their ecological influences. A total of 45 zooplankton species from 13 significant groups were recorded in the seagrass habitat. The population density of zooplankton ranged between 2,482 ind/m³ and 22,670 ind/m³ over three different seasons. A single zooplankton copepod was found to be dominant (47.40%), while bivalves were the second largest (31.8%) group in terms of total abundance. It was also noticed that the average relative abundance (0.62) and important species index (62.08) of copepods were higher than for other groups that exist in the seagrass meadow, whereas copepod Parvocalanus crassirostris showed both the highest average relative abundance (0.41) and the highest important species index (41.15). The diversity (H') and richness index of the intermediate season were found to be highest due to favourable physico-chemical conditions. Within the referred seasonal cluster, the wet and dry seasons were almost similar in terms of species abundance, while the intermediate season was distinct, with high species diversity backed by ANOSIM analysis results. Copepod and bivalves formed one group with a common similarity level of 0.80. The CCA (Canonical Correspondence Analysis) model established that abiotic factors, especially turbidity, NO2, rainfall, dissolved oxygen and pH were significantly correlated with abundance of individual groups of zooplankton. Zooplankton assemblage and abundance in Lawas were found to be very rich in multiple seasons, indicating that the productivity of uninterrupted seagrass habitat might be high and the system rich in biodiversity.
tropical, copepod, bivalve, mangrove, coastal, Borneo
Seagrass habitats are well known for their large spectrum of ecological services, including shelter, nursing, feeding and provision of breeding places for many marine organisms, such as fishes (
The fish feeding habit for zooplankton species varies between day and night and with presence of surface- and benthic-dwelling zooplankton species, while the presence of the maximum number of zooplankton taxa in a specific habitat, co-existing with different trophic level fishes correlates to the health of an ecosystem (
Copepods represent the major zooplankton group of primary consumers, playing a crucial role in the cycling of nutrients and energy, both in the marine ecosystem and seagrass meadows, by forming a trophodynamic link between primary (phytoplankton) and tertiary (planktivorous fish) production (
Some zooplankton studies were performed in different habitats, including freshwater lakes, river estuaries and coastal water in both West Malaysia (
Sarawak is a significant Province located in East Malaysia, where the existence of seagrass meadows is relatively confined to one place, Punang-Sari River Estuary, Lawas (
The seagrass habitat of Lawas is located on the south-eastern corner of the South China Sea, within Brunei Bay (Fig.
Zooplankton was collected using a plankton net with a mesh size of 150 μm and diameter of 0.3 m. The plankton net was towed horizontally at a constant speed for three minutes at near-surface depth. The volume of water filtered by the plankton net was determined from a flow meter attached to the net and net dimensions. Three sampling exercises were conducted with three replications, once during each season. Three zooplankton samples were collected randomly within the study area for each season. All the samples were collected during the day time only. The zooplankton samples were preserved in 4% formalin (
Water pH, temperature, salinity, turbidity, conductivity and dissolved oxygen were recorded in situ using a Hydrolab DS5X multiparameter water quality sonde. Besides, triplicate surface water samples were collected from the sampling location for further analysis. The water samples were brought to the laboratory and were tested for dissolved inorganic phosphate following the ascorbic acid method, ammonia following the Phenate method (
Important Species Indices (ISIs) were calculated for each taxon through the multiplication of average relative abundance and frequency data from all sampling sites, according to the methods described by
A total of 45 zooplankton species were identified and documented from the seagrass bed of Lawas, which belonged to 13 significant groups of zooplankton comprising copepods, cnidarians, bivalves, gastropoda, cladocerans, lucifer, mysids, chaetognaths, appendicularian, larvae of polychaeta, larvae of crustacean, larvae of echinoderm and fish larvae (Table
Taxa |
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Phylum Arthropoda Class Hexanauplia Order Calanoida Acartia erythraea Acartia pacifica Acartia sp. Canthocalanus pauper Centropages furcatus Acrocalanus gibber Acrocalanus gracilis Bestiolina similis Delibus nudus Parvocalanus crassirostris Parvocalanus elegans Paracalanus parvus parvus Calanopia sp. Labidocera pavo Pontellidae Pseudodiaptomus sp. Temora turbinata Tortanus barbatus Order Cyclopoida Oithona attenuata Oithona fallax Dioithona oculata Oithona plumifera Oithona simplex Hemicyclops sp. Ditrichocorycaeus andrewsi Ditrichocorycaeus asiaticus Ditrichocorycaeus erythraeus Ditrichocorycaeus subtilis Oncaea sp. |
Phylum Arthropoda Class Hexanauplia Order Mormonilloida Mormonillidae Order Harpacticoida Clytemnestra scutellata Microsetella norvegica Euterpina acutifrons Nitokra sp. Class Branchiopoda Cladocera Class Malacostraca Mysid Class Decapoda Lucifer sp. Crustacea larvae Phylum Chaetognatha Sagitta sp. Phylum Mollusca Class Bivalvia Bivalvia larvae Class Gastropoda Gastropoda larvae Phylum Polychaeta Polychaeta larvae Phylum Cnidaria Cnidaria larvae Phylum Echinodermata Echinodermata larvae Phylum Phoronida Phoronida larvae Phylum Chordata Class Appendicularia Oikopleura sp. |
The population density of zooplankton ranged from 2,482.3 ind/m³ to 22,670.0 ind/m³ in three different seasons. The single dominant group copepod had the highest abundance in the intermediate season (8,827.33 ± 3,228.95 ind/m³), followed by the wet season (3,491.00 ± 1,252.38 ind/m³) and dry season (1,610.67 ± 1,095.29 ind/m³), respectively. Larvae of bivalves was the other major group found besides copepods, with the highest abundance of bivalve observed in the intermediate season (8,787.67 ± 1,711.78 ind/m³), followed by the dry season (445.0 ± 298.82 ind/m³) and wet season (111.33 ± 45.32 ind/m³) (Table
Seasonal zooplankton distribution (mean value ± SE, ind/m3) of seagrass beds in Lawas Estuary.
Zooplankton Group |
Intermediate |
Wet |
Dry |
Copepod |
8827.33 ± 3228.95a (38.94%) |
3491.00 ± 1252.38a (82.46%) |
1610.67 ± 1095.29a (64.89%) |
Cnidaria |
43.33 ± 43.33a (0.19%) |
2.67 ± 2.67a (0.06%) |
3.67 ± 2.33a (0.15%) |
Bivalvia |
8787.67 ± 1711.78a (38.76%) |
111.33 ± 45.32b (2.63%) |
445.0 ± 298.82b (17.93%) |
Gastropoda |
3291.33 ± 608.68a (14.52%) |
36.0 ± 17.09b (0.85%) |
142.0 ± 34.95b (5.72%) |
Cladocera |
71.67 ± 57.32a (0.32%) |
0.00 ± 0.00a (0%) |
3.0 ± 3.0a (0.12%) |
Luciferidae |
9.67 ± 9.67a (0.04%) |
13.0 ± 8.14a (0.31%) |
2.0 ± 1.0a (0.08%) |
Mysida |
20.0 ± 10.02a (0.09%) |
6.33 ± 3.28a (0.15%) |
9.67 ± 6.89a (0.39%) |
Chaetognatha |
477.67 ± 251.42a (2.11%) |
139.33 ± 92.96a (3.29%) |
36.0 ± 31.51a (1.45%) |
Appendicularia |
174.67 ± 36.04a (0.77%) |
305.0 ± 204.78a (7.20%) |
28.33 ± 23.85a (1.14%) |
Polychaeta larv. |
522.67 ± 62.52a (2.31%) |
24.0 ± 16.65b (0.57%) |
10.67 ± 6.69b (0.43%) |
Crustacean larv. |
405.00 ± 156.56a (1.79%) |
97.33 ± 37.74a (2.30%) |
191.33 ± 37.34a (7.71%) |
Echinoderm larv. |
4.67 ± 4.67a (0.02%) |
0.00 ± 0.00a (0%) |
0.00 ± 0.00a (0%) |
Actinotroch larv. |
24.67 ± 12.81a (0.11%) |
0.00 ± 0.00a (0%) |
0.00 ± 0.00a (0%) |
Fish larvae |
9.67 ± 4.84a (0.04%) |
7.33 ± 4.06a (0.17%) |
0.00 ± 0.00a (0%) |
Total |
22670 ± 6198.62 |
4233.33 ± 1685.073 |
2482.33 ± 1541.67 |
**Different superscripts within the same row indicate significant differences (p < 0.05).
The major groups of zooplankton during the study periods were non-copepod (52.6%), while the copepod group comprised 47.40%, whereas a single copepod was found dominant. Non-copepods included: larvae of Bivalvia (31.80%), larvae of Gastropoda (11.8%), larvae of Crustacean (2.36%), Chaetognatha (2.22%), larvae of Polychaeta (1.90%), Appendicularia (1.73%) and others (0.78%) inclusive of Cladocera (0.25%), larvae of Cnidaria (0.17%), larvae of Mysida (0.12%), larvae of Echinoderm (0.02%), larvae/egg of fishes (0.06%), Luciferidae (0.08%) and larvae of Actinotroch (0.08%). The intermediate season showed an abundance of copepod (38.94%) and bivalves (38.76%) that was almost similar, but, in the wet and dry season, copepod was the largest group in terms of zooplankton abundance, at 82.46% and 64.89%, respectively.
The average abundance within zooplankton groups revealed that copepod (13,929.3 ± 2,161.47 ind/m³) (47.4%) was the most abundant in all three seasons, amongst all groups, followed by larvae of Bivalvia (9,344.24 ± 2838.11 ind/m³), larvae of Gastropoda (3,468.92 ± 1067.90 ind/m³), larvae of Crustacean (693.67 ± 91.03 ind/m³) and larvae of Echinoderm (4.80 ± 1.60 ind/m³) with the lowest abundance (Table 3). The average relative abundance maintained a similar trend to the average abundance, where copepod (0.62) was the highest in relative abundance, followed by larvae of Bivalvia (0.20), larvae of Gastropoda (0.07), larvae of Crustacean (0.04) and larvae of fishes (0.0007) with the lowest relative abundance. The frequency of most species was almost 100% in every season, as members from most of the groups were observed in every season. The important species index showed that copepod (62.08) was the most important zooplankton group in the seagrass habitat, whereas Bivalvia (19.76) and Gastropoda (7.02) also had importance to maintain the biotic integrity of the seagrass habitat (Table
Zooplankton groups with their total abundance (mean value ± SE, ind/m3), mean Relative Abundance (RA), occurrence frequency (%F) and Important Species Index (ISI).
Zooplankton Group |
Total Abundance |
RA |
F |
ISI |
Copepod |
13929.3 ± 2161.47 (47.4%) |
0.62 |
100.0 |
62.08 |
Cnidaria |
49.67 ± 13.39 (0.17%) |
< 0.01 |
100.0 |
0.13 |
Bivalvia |
9344.24 ± 2838.11 (31.8%) |
0.20 |
100.0 |
19.76 |
Gastropoda |
3468.92 ± 1067.90 (11.8%) |
0.07 |
100.0 |
7.02 |
Cladocera |
74.53 ± 23.30 (0.25%) |
< 0.01 |
66.7 |
0.10 |
Luciferidae |
24.63 ± 3.22 (0.08%) |
< 0.01 |
100.0 |
0.14 |
Mysida |
35.86 ± 4.07 (0.12%) |
< 0.01 |
100.0 |
0.21 |
Chaetognatha |
653.34 ± 133.44 (2.22%) |
0.02 |
100.0 |
2.28 |
Appendicularia |
508.07 ± 79.87 (1.73%) |
0.03 |
100.0 |
3.04 |
Polychaeta larv. |
557.34 ± 168.55 (1.9%) |
0.01 |
100.0 |
1.10 |
Crustacean larv. |
693.67 ± 91.03 (2.36%) |
0.04 |
100.0 |
3.93 |
Echinoderm larv. |
4.80 ± 1.60 (0.02%) |
< 0.01 |
33.3 |
< 0.01 |
Actinotroch larv. |
24.67 ± 8. 22 (0.08%) |
< 0.01 |
33.3 |
0.01 |
Fish larvae |
17.0 ± 2.91 (0.06%) |
< 0.01 |
66.7 |
0.05 |
As copepod is a significant and abundant zooplankton group found at Lawas seagrass habitat, the present study also focused on species composition, average relative abundance, frequency and important species index of this group. Where revealed, the Relative Abundance (RA) and Important Species Index (ISI) of Parvocalanus crassirostris (RA; 0.41 and ISI; 41.15) was the highest amongst all copepod species and found in every season of the year (frequency, 100), followed by Bestiolina similis (RA; 0.13 and ISI; 12.82), Oithona simplex (RA; 0.12 and ISI; 11.52), Pontellidae sp.1 (RA; 0.1and ISI; 9.51) and so on (Table
Copepod species with their annual mean Relative Abundance (RA) and Important Species Index (ISI).
Species |
RA |
ISI |
Species |
RA |
ISI |
Acartia erythraea |
0.02 |
1.51 |
Labidocera pavo |
0.0007 |
0.03 |
Acartia pacifica |
0.003 |
0.13 |
Microsetella norvegica |
0.0003 |
0.01 |
Acartia sp. |
0.04 |
4.02 |
Mormonillidae sp. |
0.004 |
0.42 |
Acrocalanus gibber |
0.003 |
0.32 |
Nitokra sp. |
0.005 |
0.54 |
Acrocalanus gracilis |
0.0003 |
0.01 |
Oithona attenuate |
0.0007 |
0.05 |
Bestiolina similis |
0.13 |
12.82 |
Oithona fallax |
0.02 |
1.23 |
Calanopia sp. |
0.0001 |
0.006 |
Dioithona oculate |
0.04 |
4.04 |
Canthocalanus pauper |
0.004 |
0.41 |
Oithona plumifera |
0.001 |
0.06 |
Centropages furcatus |
0.004 |
0.27 |
Oithona simplex |
0.12 |
11.52 |
Clytemnestra scutellata |
0.0005 |
0.02 |
Oncaea sp. |
0.0008 |
0.03 |
Ditrichocorycaeus andrewsi |
0.01 |
1.39 |
Parvocalanus crassirostris |
0.41 |
41.15 |
Ditrichocorycaeus asiaticus |
0.0001 |
0.006 |
Parvocalanus elegans |
0.02 |
1.18 |
Ditrichocorycaeus erythraeus |
0.0007 |
0.02 |
Paracalanus parvus parvus |
0.02 |
1.6 |
Ditrichocorycaeus subtilis |
0.006 |
0.67 |
Pontellidae sp. |
0.1 |
9.51 |
Delibus nudus |
0.009 |
0.65 |
Pseudodiaptomus sp. |
0.0003 |
0.01 |
Euterpina acutifrons |
0.008 |
0.84 |
Temora turbinate |
0.02 |
1.72 |
Hemicyclops sp. |
0.005 |
0.5 |
Tortanus barbatus |
0.001 |
0.1 |
The intermediate season recorded the highest number of species (45 species/group) or groups of zooplankton amongst all seasons, followed by the wet and dry seasons (both with 30 species/group). The wet season (0.31) showed a significantly (p < 0.0001) higher Simpson Dominance Index, followed by the dry season (0.17) and intermediate season (0.13). The Diversity Index was significantly (p < 0.0001) higher in the intermediate season (2.55), followed by the dry season (2.26) and wet seasons (1.78), while the Evenness Index was found significantly (p < 0.0001) highest at dry season (0.32). Species Richness Index was found significantly (p < 0.0001) higher in the intermediate season (4.15), followed by dry (3.34) and wet seasons (3.11) (Fig.
Amongst all the parameters, dissolved oxygen was found significantly different (p < 0.03) in all three seasons, where dissolved oxygen in the intermediate season was found the highest (6.66 mg/l) and lowest in the dry season (3.76 mg/l). Water-NH4 concentration was found significantly different (p < 0.0005) in all three seasons, where the dry season showed the highest (0.52 mg/l) NH4 concentration and intermediate season the lowest (0.08 mg/l). Water-NO2 concentration was found significantly different (p < 0.0001) in all three seasons, where the intermediate season showed the highest (0.39 mg/l) and the dry season the lowest (0.04 mg/l). Rainfall was found significantly different (p < 0.0001) in all three seasons, where the intermediate season showed the highest rainfall (706.10 mm) and dry season the lowest (515.75 mm) (Table
Summary result of two-way ANOVA and Tukey HSD test on various abiotic factors.
Water quality parameters |
Intermediate |
Wet |
Dry |
p-value |
Temperature (⁰C) |
27.03 ± 0.14a |
29.79 ± 0.29a |
29.26 ± 1.47a |
> 0.05 |
pH |
7.88 ± 0.04a |
7.72 ± 0.02a |
7.10 ± 0.45a |
> 0.05 |
Salinity (PSU) |
25.63 ± 0.04a |
27.31 ± 0.51a |
20.20 ± 4.72a |
> 0.05 |
Conductivity (mS/cm) |
40.10 ± 0.05a |
42.47 ± 0.73a |
32.19 ± 6.75a |
> 0.05 |
DO (mg/l) |
6.66 ± 0.03a |
5.31 ± 0.05ab |
3.76 ± 0.93b |
< 0.05 |
Turbidity (NTU) |
52.90 ± 28.29a |
28.83 ± 1.48a |
45.17 ± 8.41a |
>0.05 |
NH4 (mg/l) |
0.08 ± 0.01b |
0.14 ± 0.07b |
0.52 ± 0.01a |
< 0.05 |
NO3 (mg/l) |
0.63 ± 0.17a |
0.84 ± 0.23a |
1.01 ± 0.22a |
> 0.05 |
NO2 (mg/l) |
0.39 ± 0.02a |
0.14 ± 0.02b |
0.04 ± 0.02c |
< 0.0001 |
PO4 (mg/l) |
0.002 ± 0.00a |
0.006 ± 0.00a |
0.02 ± 0.02a |
> 0.05 |
TSS (mg/l) |
15.64 ± 1.79a |
41.40 ± 9.99a |
29.67 ± 6.68a |
> 0.05 |
Chl a (mg/m3) |
0.10 ± 0.02a |
0.84 ± 0.43a |
1.27 ± 0.53a |
> 0.05 |
Rainfall (mm) |
706.10 ± 0.00a |
589.38 ± 0.00b |
515.75 ± 0.00c |
< 0.0001 |
Values mean ± SE; **Different superscripts within the same row indicate significant differences (p < 0.05) (Adopted from
Cluster analysis of zooplankton abundance, based on Bray-Curtis, showed a clear inter-seasonal grouping in all three seasons. The dendrogram presents zooplankton density in three seasons, generally classified into two groups at the similarity level of 0.58, based on the difference of seasons (Cophen. Correlation, 0.9624) (Fig.
The intermediate season is separated from dry and wet seasonal clusters, which indicates that the intermediate season was found very different from the other two seasons. Cluster analysis of zooplankton abundance in species and groups, based on Bray-Curtis (Cophen. Correlation, 0.9387), showed several similar groups, where copepods and bivalves together formed one group with a similarity level of 0.80, indicating that these two groups of zooplankton had the highest abundance in all three seasons (Fig.
The ANOSIM analysis revealed that the dry and wet seasons had very similar species abundance, with the intermediate season found to be very dissimilar to wet (similarity index, 0.1075) and dry seasons (similarity index, 0.0966). However, the wet season was found to be very similar to the dry season (similarity index, 0.5943).
The first Canonical axis of the variance in zooplankton abundance accounted for 90.81% (Eigenvalue, 0.14) and the second axis accounted for 9.19% (Eigenvalue, 0.01). Thus, the first two axes comprised cumulative 100% of the variance. The CCA model confirmed that key abiotic factors, turbidity, NO2, rainfall, dissolved oxygen and pH, were all highly correlated with the individual group of zooplankton abundance; where turbidity (Eigenvalue, 0.97), NO2 (Eigenvalue, 0.73), total rainfall (Eigenvalue, 0.66), dissolved oxygen (Eigenvalue, 0.49) and pH (0.22) were positively correlated to zooplankton abundance in the first axis, while salinity (Eigenvalue, -0.99) and specific conductivity (Eigenvalue, -0.99) both showed negative correlation with zooplankton abundance in the second axis (Fig.
The present study exhibits the distribution, seasonal zooplankton dynamics and ecological abiotic factors that impact the zooplankton population in Malaysia's tropical seagrass habitat. Previous studies have denoted planktonic communities as indicators of water quality (
The present study revealed the zooplankton ranges from 2,482.33 ind/m³ to 22,670.0 ind/m³ in the three mentioned seasons, where the intermediate season (22,670 ± 6,198.62 ind/m³) recorded the highest zooplankton abundance amongst seasons. Comparative zooplankton studies with zooplankton number and abundance are recorded in Table
Comparison of zooplankton abundance with other studies in the different habitat.
Habitat |
Abundance (ind/m3) |
Mesh size |
Reference |
Seagrass meadow Johor, Malaysia |
17.0 to 104.00 |
100 μm |
|
Seagrass bed, Merambong shoal |
3,030.16 to 4,006.50 |
140 μm |
|
Seagrass bed, Pulau Tinggi, Johor |
1,245.00 |
100 μm |
|
Lupar & Sadong river estuary, Sarawak |
447.50 to 27812.90 |
150 μm |
|
Bintulu coastal water, Sarawak |
183 to 7,238.00 |
153 μm |
|
Seagrass bed, south-western Atlantic |
7,113.00 |
300 μm |
|
Seagrass bed, Mandapam Coast |
935,300.00 |
NA |
|
Seagrass, Punang-Sari Estuary, Lawas |
2482.33 to 22670.00 |
150 μm |
Present study |
Studies have revealed that, as a single group, copepod comprises a significant portion of zooplankton in different habitats, including estuarine, mangrove and seagrass (
Copepod, ranged from 1,610.67 ± 1,095.29 to 8,827.33 ± 3,228.95 ind/m³ in dry and intermediate seasons, with an average of 13,929.3 ± 2,161.47 ind/m³, followed by larvae of Bivalvia 31.80%, larvae of Gastropoda 11.8%, larvae of Crustacean 2.36%, Chaetognatha 2.22%, larvae of Polychaeta 1.90%, Appendicularia 1.73% and others (0.78%). The intermediate season being found rich in various species and groups might have been due to nutritional abundance, availability of rich phytoplankton and ocean current. However, the present findings are similar to the studies of
The relative abundance of zooplankton followed the abundance pattern, such that copepods (0.62) were the highest in average relative abundance, followed by larvae of Bivalvia (0.20), larvae of Gastropoda (0.07), larvae of Crustacean (0.04) and fish larvae (0.0007) with the lowest relative abundance.
As copepods were the largest zooplankton group, the current study has accounted for copepod zooplankton as the most important biotic fauna in seagrass meadows. We have calculated the relative abundance (RA) and Important Species Index (ISI) of all available copepods in Lawas. Parvocalanus crassirostris was the highest in density amongst all copepod species and found in every season of the year, followed by Bestiolina similis, Oithona simplex, Pontellidae sp.1, Dioithona oculata, Acartia sp., Temora turbinata, Paracalanus parvus parvus, Acartia erythraea, Ditrichocorycaeus andrewsi, Oithona fallax, Parvocalanus elegans and so on.
The majority of the copepod species from the genus of Paracalanus, Oithona and Acartia are predominant in Malaysian waters and especially abundant in the nearshore and within estuaries (
Fluctuations in zooplankton communities and their distribution have noteworthy impacts on fishery resources because of the significant role they play within the aquatic food web. The temporal changes in abundance of zooplankton affect the availability of dependent species, fishes for example. Temporal variation of zooplankton in the current study of Lawas seagrass meadows, revealed that the abundance of bivalves (38.76%) and copepods (38.94%) were almost similar in the intermediate season, but in the wet and dry seasons, copepods formed the largest, most abundant zooplankton group at 82.46% and 64.89%, respectively.
In the present study, the Diversity Index was the highest in the intermediate season (2.55), followed by the dry season (2.26) and the wet season (1.78), while the Evenness Index was found the highest in the dry season (0.32). Species Richness Index was found the highest in the intermediate season (4.15), followed by the dry (3.36) and wet seasons (3.11), which it was found similar to other studies, including those of
Water quality plays a vital role to maintain zooplankton abundance, with some parameters considered significant, such as dissolved oxygen. In the present study, dissolved oxygen was the highest in the intermediate season and lowest in the dry season. Water-NH4 concentration was found significantly different (p < 0.0005) in all three seasons, with the dry season showing the highest NH4 concentration and intermediate season the lowest. The NO2 concentration was found significantly different (p < 0.0001) in all three seasons, with the intermediate season showing the highest concentration and dry season the lowest. Rainfall was found significantly different (p < 0.0001) in all three seasons with the intermediate season having the highest, and dry season the lowest rainfall. The present findings are very similar to the studies of
Cluster analysis of zooplankton abundance, based on Bray-Curtis, showed a clear inter-seasonal and inter-group clustering in all three seasons. Two clear groups were formed in seasonal clustering at the similarity level of 0.58, but as several group clusters. Amongst these, the most crucial cluster was the bivalve-copepod group, which was the most abundant group in all seasons with a similarity level of 0.80. A similar cluster analysis was performed by
Canonical Correspondence Analysis (CCA) revealed some key abiotic factors, including turbidity, NO2 concentration, rainfall, dissolved oxygen and pH, which were highly correlated with an individual group of zooplankton abundance.
The seagrass meadows of Punang-Sari Estuary, Lawas, are very rich in species diversity, including zooplankton, fishes and macrobenthos, which contribute ecologically and economically to both the alpha biodiversity and the local population, respectively. Abundance of year-round zooplankton will ensure the availability of a variety of fishes and support some ecologically and economically essential species within the area. As seagrass meadows are such a productive habitat, made rich by the presence of zooplankton, zooplankton can be considered for establishment as a baseline indicator in this habitat. Further study of zooplankton abundance, composition and ecology on available fish species is recommended.
The authors extend gratitude to Mr. Othman bin Dinin (Kampung Punang resident and fisherman), Mr. Awangku Nizam Awang Saberan (UPM) and Mr. Meruni Merchang (UPM) for assistance during field sampling.
This research was supported by Universiti Putra Malaysia through Project UPM/800/2/2/4-Geran Putra, Vot. No. 9662800.
UPM/800/2/2/4-Geran Putra
Universiti Putra Malaysia
None to declare.
Conceptualisation—JI and AHMK; methodology—JI; statistical analysis— AAA; data curation— JI and AAA; writing original-draft preparatiton—JI, AHMK and AAA; writing, review and editing— MHI, SMNNA, HH, LSS and MHA all authors have read and agreed to the published version of the manuscript.
None to declare.