Meiofauna from Almirante Câmara Canyon and Its Adjacent Open Slope, Southwest Atlantic Ocean
by
, ,
André M. Esteves
1,*
,
Verônica S. Oliveira
1,
Paulo J. P. dos Santos
1,
Tatiana F. Maria
2 and
Adriane P. Wandeness
1 1
Departamento de Zoologia, Universidade Federal de Pernambuco, Recife 50670-901, Brazil
2
Departamento de Ecologia e Recursos Marinhos, Universidade Federal do Estado do Rio de Janeiro, Rio de Janeiro 22290-240, Brazil
*
Author to whom correspondence should be addressed.
Coasts 2025, 5(2), 14; https://doi.org/10.3390/coasts5020014
Submission received: 12 December 2024
/
Revised: 14 April 2025
/
Accepted: 15 April 2025
/
Published: 17 April 2025
Abstract
:The patterns of meiofaunal distribution in a submarine canyon and adjacent open-slope habitats at Campos Basin, southwest Atlantic, were investigated. A total of eight stations was sampled, four inside the Canyon Almirante Câmara and four on the adjacent open slope. These stations represented four isobaths (400, 700, 1000, 1300 m) and were sampled during two distinct periods (2008, 2009). At each station, three replicates were obtained and sectioned into layers of 0–2, 2–5 and 5–10 cm. Nematoda was the most abundant group in both habitats, comprising more than 85% of the total meiofauna in both sampling periods. The density and assemblage structure of the meiofauna showed high variability between the 400 m isobath and the other three isobaths in the canyon habitat. These results reinforce the roles of habitat heterogeneity and the availability of food sources as key factors strongly influencing the deep-sea meiofauna in the southwest Atlantic Ocean. Phytopigments were significantly correlated with the two major meiofaunal groups (Nematoda and Copepoda), as well as with total meiofaunal density, only in the canyon habitat. On the adjacent open slope, only copepods showed a significant correlation with sediment characteristics (mean grain size and carbonates), suggesting that distinct environmental factors influence the distribution of meiofauna in the two habitats.
1. Introduction
Most continental margins are cut by submarine canyons [1], which are spectacular features of the continental margin and contribute substantially to the channeling of water, sediment and organic matter from the land to the deep basins. Some canyons are also considered “hot spots” of benthic diversity; these are typically characterized by high levels of endemism and patterns of local species exhibiting peculiar life histories [2]. These deep and relatively narrow U- or V-shaped valleys are largely unexplored environments [3] and have an important role in transporting sediments from coastal areas to the deep sea, where these sediments support a wide diversity of life [4,5,6].
A variety of organisms inhabiting marine sediments play important roles in many ecosystem processes, including the recycling of nutrients, food-web dynamics, decomposition, mineralization and storage of organic matter. These processes are maintained by the relationships between organisms and their physical and chemical environments [7].
Among these organisms, the meiofauna are the most abundant group of animals in marine benthic systems. It is usually dominated by nematodes and copepods (which generally comprise more than 80% of the total assemblage) [7]. Due to the enhanced deposition of organic matter in canyons, meiofaunal biomass and diversity tend to be higher in these areas [8] and it is also concentrated in the top few centimeters of the marine seabed. The assessment of meiofauna is crucial to understanding the dynamics of deep-sea ecosystems and biogeochemical cycling since these organisms play a variety of ecological roles, including bioturbation, biochemical cycling, trophic cascades, grazing and predation [9].
The southwest Atlantic deep sea is characterized by the presence of several canyons, and previous investigations have revealed that canyons in the Atlantic Ocean are subjected to lateral transport, which promotes sediment enrichment in phytodetritus, particulate organic carbon and nucleic acids, particularly near the head of the canyon [10]. Some of these canyons are considered active or mature, i.e., they are characterized by gravitational fluxes [3] and may act as traps for labile organic matter. The combination of these conditions may allow a higher density and diversity of meiofaunal organisms to live in the canyon area than on the adjacent open slope. especially in shallow isobaths. In this study, we aimed to characterize the distribution of meiofauna in and near a submarine canyon at Campos Basin, SW Atlantic. Benthic fauna was sampled at eight stations, four inside Canyon Almirante Câmara and four on the adjacent open slope.
2. Materials and Methods
2.1. Study Area and Sampling
The Campos Basin is located in the southwest margin of the South Atlantic Ocean and occupies a portion of the Brazilian continental margin between 20.5° S (Vitória Ridge) and 24° S (Cabo Frio Ridge) over an area of more than 100,000 km2 [11]. This area contains several canyons that carry sediment into the deep sea, and it is commercially important for oil and gas exploitation [12]. The Canyon Almirante Camera is 28 km long and 4 km wide and has a “characteristic zig-zag general trend”. The V-shaped thalweg (central channel) is 3.5 km wide and 150 m deep [5].
Sampling was carried out during the cruises of the HABITATS project, which was coordinated by Petrobras S.A (Rio de Janeiro, Brazil). For this study, four stations within Almirante Câmara Canyon and four stations on the adjacent open slope were sampled (Figure 1). Canyons and adjacent slope areas were considered to represent habitats. Stations were located in four different isobaths (400 m, 700 m, 1000 m and 1300 m) in each habitat. Samplings were carried out in two sampling periods, May 2008 and February 2009. The sediment samples were collected using a box corer (Benthic Solutions, Norwich, UK) with dimensions of 50 cm × 50 cm × 50 cm, divided into 25 sub-squares of 10 × 10 cm. After each deployment of the box corer, a single sample with a depth of 10 cm was obtained from one subsquare, and each sample was vertically sliced into layers of 0–2 cm, 2–5 cm and 5–10 cm. A total of three independent replicates for each layer, were included in the analysis of the meiofauna. In the analyses of phytopigment (chla and pheophytin) concentrations, granulometry and total organic carbon (TOC), only the surface layer was analyzed at each sampling station.
2.2. Sample Processing
For the analysis of environmental sediment variables (granulometry, carbonates, TOC, phytopigments), the samples were preserved at −20 °C until analysis in the laboratory [13].
Sediment particle-size distribution was determined using a Beckman Coulter LS100_ particle-size counter (Malvern Panalytical Ltd., Malvern, UK). The sediment fractions were defined according to the Wentworth scale. Chlorophyll a was extracted in 90% acetone and measured with a Turner fluorometer [13].
For meiofaunal analysis, each sediment sample was transferred to a plastic flask and fixed in 10% formalin buffered with borax. Samples were sieved through a 500 μm mesh, and a 45 μm mesh was used to retain the meiobenthic organisms. The fraction remaining on the 45 μm mesh was extracted six times using a flotation method based on colloidal silica (diluted with distilled water to a final density of 1.18 g cm−3) [14]. The meiofauna were counted and identified to the level of major taxa under a stereomicroscope (OLYMPUS SZ 40, Olympus, Hamburg, Germany).
2.3. Data Analysis
Total density (ind. 10 cm−2) was calculated for each station and habitat. A PERMANOVA analysis was carried out to test for differences in number of groups, density, diversity and assemblages (total meiofauna and rare taxa) among stations [15]. For univariate data, a Euclidian distance matrix was used, while for multivariate data, a Bray–Curtis similarity matrix was applied. For all PERMANOVA analyses, four fixed factors were considered: habitats—HA (two levels: canyon vs. adjacent open slope), isobaths—ISO (four levels: 400 m, 700 m, 1000 m and 1300 m), layer—LAY (three levels: 0–2 cm, 2–5 cm and 5–10 cm), and sampling period—PD (two levels: May 2008 vs. February 2009). Meiofaunal assemblage data were square-root transformed and environmental factors were normalized. In cases of significant interactions, pairwise tests were performed.
Based on the similarity matrix, a nonmetric multidimensional scaling ordination (nMDS) was performed. Spearman’s rank correlation coefficient was used to detect relationships between densities of meiofauna, nematodes and copepods and environmental variables [16]. To assess which environmental variable most strongly influenced the distribution of the meiofaunal assemblage, a DistLM (Distance-Based Linear Models) was generated after assessment for highly correlated variables, which were excluded from the analysis. This analysis was performed on transformed (log x + 1) and normalized environmental variables, using a sequential stepwise selection procedure with the Akaike information selection criterion (AIC) for multivariate response variables.
All multivariate analyses and calculations of univariate diversity indices were performed using the PRIMER v6.1.15 with PERMANOVA + v1.0.5 add-on software package [17].
3. Results and Discussion
The meiofauna were composed of 21 groups: Turbellaria, Rotifera, Gastrotricha, Kinorhyncha, Loricifera, Nematoda, Priapulida, Sipuncula, Aplacophora, Bivalvia, Gastropoda, Tardigrada, Oligochaeta, Polychaeta, Acari, Amphipoda, Copepoda, Cumacea, Isopoda, Ostracoda and Tanaidacea. The taxonomic compositions of the meiofaunal assemblages recorded in the canyon and on its adjacent open slope were similar to those found in other studies of deep-sea areas in the northeastern Mediterranean Sea [18], the northeastern Atlantic Ocean [19] and the Atlantic Ocean and Mediterranean Sea [4].
The meiofaunal richness ranged from 5 to 14 taxa and showed significant differences for the interaction term HA × ISO × LAY. The highest richness was found in the upper layer of the canyon habitat in the 1000 m isobath (Figure 2 and Table 1). Apart from this difference, results indicate that the canyon and its adjacent open area supported a similar number of meiofaunal groups regardless of layers, depths and sampling periods (Appendix A, Table A1). Previous studies comparing canyons with adjacent open slopes reported similar numbers of taxa between these two habitats in the Northeastern Atlantic Ocean and Mediterranean Sea [4].
As was expected, Nematoda was the most abundant group, representing more than 93% and more than 89% of the total meiofauna in May 2008 and February 2009, respectively. Copepoda, the second-most-abundant group, composed approximately 3% of the total in May 2008 and doubled in abundance to over 6% in February 2009. The other meiofaunal groups composed less than 2% of the total abundance (Figure 3). The dominance of nematodes and copepods in samples of meiofauna is normal for several ecosystems and is widely reported for deep-sea areas worldwide [20,21,22,23].
The structure of the meiofaunal assemblages, as determined based exclusively on the rare taxa, is shown in Figure 4. Temporary fauna accounted for 42–92% and 50–92% of the total abundance of rare taxa in the canyon and adjacent open-slope habitats, respectively. These abundances surpass those encountered in other deep-sea areas [4]. Most of the temporary fauna were found in both habitats, except for Cumacea, Cnidaria and Nemertea, with the latter two taxa found exclusively in the adjacent open-slope habitat. Polychaetes showed increased abundance towards the subsurface layers in both habitats (Figure 4). The results of the PERMANOVA tests carried out for the assemblages of rare taxa revealed differences based on the interaction term HA × ISO × LAY (Table 1). The assemblages of rare taxa from canyons and the adjacent open slope were different in the subsurface layer (2–5 cm) in the 400 m and 1000 m isobaths and at the deeper layer (5–10 cm) in the 400 m isobath (Appendix A, Table A1). Polychaetes become more important in the subsurface layer of the adjacent open-slope habitat in the 400 and 700 m isobaths, but their abundance was reduced in the 1000 m isobath in this habitat (Figure 4). Several of the polychaete families reported in this study are considered subsurface deposit feeders and are commonly found in deep-sea canyon and noncanyon habitats [6].
Meiofaunal densities in sediments of the canyon and its adjacent open slope from Campos Basin were higher than those reported by other studies (Table 2). Although high densities of meiofauna are usually attributed to differences in the sedimentary matrix [7], this explanation may not apply to the deep sea, as the sediments in these geographic regions have similar grain sizes (e.g., they are mostly silt and clay).
The highest meiofaunal densities were observed in the canyon habitat, independent of the sediment layer, in May 2008 (Figure 5). PERMANOVA tests detected significant differences for total meiofaunal density for the interaction term HA × PD × LAY (Table 1). Pairwise tests indicated that significant differences were present between the habitats among layers only for the first sampling period (Table 3).
Previous studies in the same area dealing with organisms belonging to different size classes (from foraminiferans to macrofauna/megafauna), have found a greater abundance of fauna in canyon systems than in the adjacent open areas [5,26]. A similar pattern was also observed in different areas of canyons in the eastern North Atlantic and the Mediterranean Sea [4]. A clear pattern of reduced density with increasing depth [27,28] is well documented in the literature. Similarly, a lack of consistent bathymetric patterns among canyons and between canyons and slopes for meiofauna has been well documented [29] and is mostly attributed to local differences concerning the physical and geological complexity of the continental slope and interactions with overlying water-column processes [30]. Here, no bathymetric profile was evident, but a markedly high variability in meiofaunal density was observed in the 400 m isobath.
In Almirante Canyon, the lateral transport of nutrients favors enrichment in phytodetritus, with increasing levels of particulate organic carbon and nucleic acids at the head of this habitat [31], as has been observed in other Atlantic canyons [5]. This process also favors increasing heterogeneity on both habitats. The oceanographic processes caused by the Brazilian Current over two other masses (e.g., Superficial Tropical Water and South Atlantic Central Water), even with relatively low-velocity currents [11], may also contribute to a high heterogeneity in the sedimentary matrix. The surrounding areas at the 400 m sampling station in the canyon habitat include spots of calcareous and sandy sediment (Figure 1). In contrast to faster currents, slow bottom currents allow the settlement of geological and food particles in the sea bottom [31]. These two phenomena may reflect the high variability in meiofaunal density found in the superficial layer in the 400 m canyon isobath. Therefore, the conjunction of complex hydrodynamic conditions and high local primary production in canyons systems is thought to be responsible for positive effects on the benthic fauna [4,32,33,34,35]. However, the addition of organic matter (POM) in this system occurs seasonally and in pulses, with higher inputs during the summer and seems to be reflected in a time-lagged response (e.g., two months later), with increasing meiofaunal densities in all sediment layers.
Phytopigments and carbonates were significantly correlated with the abundances of the two major groups and the total meiofaunal densities only in the canyon system (Table 4). On the adjacent open slope, only copepods showed a significant correlation with sediment characteristics (mean grain size and carbonates). These observations seem to indicate that the abundances of total meiofauna and the major groups are controlled by different environmental factors in the canyon and on the adjacent open slope. In this case, the productivity at a regional scale (e.g., in the canyon) is one of the significant positive factors influencing total densities of the meiofaunal assemblage and nematode and copepod densities. These findings indicate a strong dependence of meiofaunal density on the quantity of organic matter, as previously reported [30]. Furthermore, it emphasizes the role of meiofauna in transferring organic matter into deep-sea benthic food webs from canyon systems.
Patterns in meiofaunal community structure along the bathymetric sampling stations in canyons and on adjacent open slopes of Campos Basin are presented as a multidimensional ordination (nMDS), which showed a separation of meiofaunal assemblages by habitat, depth and layer (Figure 6, Table 1). PERMANOVA tests detected significant differences for meiofaunal assemblages for the interaction term habitat × isobath × layer (Table 1). The meiofaunal assemblage from canyons and adjacent open slopes were different in the subsurface layer (2–5 cm) in the 400 m and 1300 m isobaths and in the deeper layer (5–10 cm) in the 400 m isobath (Appendix A, Table A1). The difference observed between habitats contrasts with the findings of previous studies performed with meiofaunal assemblages from Portuguese, Catalan and South Adriatic margins [4], where canyons and open slopes were found to share the same meiofaunal assemblages. Our result reinforces the role of submarine canyons as traps for organic material of diverse origins and showcases how meiofauna react directly to the lateral transport of sedimentary organic matter from the adjacent open slope, as was already evidenced in Almirante Canyon for foraminiferans [5], though with a limited effect. In the analysis of the bathymetric stations, in both habitats, dissimilar meiofaunal assemblages were found in the 400 m isobath compared to the other, deeper isobaths from the subsurface layer onwards, but there was no bathymetric gradient with increasing depth in either habitat. The DistLM routine showed that three environmental variables (carbonates, TOC and chla) best explained the meiofaunal assemblages (24%) in the two habitats. Among the three environmental variables, chla explained 13% of the meiofaunal assemblage. Although these environmental variables accounted for a limited portion of the total variance in the meiofaunal assemblage, they reflect the importance of combined sediment features and availability of food sources in explaining meiofaunal distribution in canyons and adjacent areas.
In conclusion, our results clearly indicate that oceanographic patterns strongly influenced the variability in meiofaunal density in the surface sediment layer, particularly at the 400 m canyon station, where the taxonomic composition of rare meiofaunal taxa was also quite distinct. Organic enrichment, measured via chlorophyll a and pheophytin, together with carbonate concentration, was significantly related to variations in the density of major meiofaunal taxa at canyon stations, but not on the adjacent slope, where environmental variables such as sediment grain size affected only copepods. Although our results reinforce the role of submarine canyons in structuring the meiofaunal assemblage, the lack of a bathymetric effect on densities between depths of 700 and 1300 m was surprising. A combination of habitat heterogeneity and food sources are key factors influencing the structure and biodiversity of deep-sea meiofaunal assemblages in the Almirante Câmara Canyon and on its adjacent slope in the Campos Basin.
Author Contributions
Conceptualization: A.M.E.; methodology: V.S.O.; validation: A.M.E. and A.P.W.; formal analysis: A.M.E., P.J.P.d.S. and T.F.M.; investigation: A.M.E., A.P.W. and V.S.O.; data curation: A.M.E., A.P.W. and V.S.O.; writing—original draft preparation: A.M.E., A.P.W. and V.S.O.; writing—review and editing: A.M.E., A.P.W., P.J.P.d.S. and T.F.M. All authors have read and agreed to the published version of the manuscript.
Funding
This research received no external funding.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
The data is contained within the article.
Acknowledgments
The present study is part of the multidisciplinary environmental research project “Campos Basin Environmental Heterogeneity—HABITATS”, the main objective of which is to characterize physically, chemically and biologically the different environments on the continental margin of the Campos Basin, southeast Atlantic. So, we are grateful to CENPES/PETROBRAS for the opportunity created by the project HABITATS, which made the material available for analysis.
Conflicts of Interest
The authors declare no conflicts of interest.
Appendix A
Table A1.
Results of pairwise tests for biological variables of HA within HA × IS × LAY. Significant p-values are bold.
Table A1.
Results of pairwise tests for biological variables of HA within HA × IS × LAY. Significant p-values are bold.
| RICHNESS | 400 m | 700 m | 1000 m | 1300 m |
| 0–2 cm | 0.347 | 0.090 | 0.039 | 0.076 |
| 2–5 cm | 0.532 | 0.736 | 0.648 | 0.245 |
| 5–10 cm | 0.149 | 0.681 | 0.733 | 0.891 |
| RARE TAXA | 400 | 700 | 1000 | 1300 |
| 0–2 cm | 0.066 | 0.209 | 0.085 | 0.336 |
| 2–5 cm | 0.007 | 0.717 | 0.002 | 0.070 |
| 5–10 cm | 0.002 | 0.517 | 0.821 | 0.337 |
| MEIO ASSEMBLAGE | 400 | 700 | 1000 | 1300 |
| 0–2 cm | 0.139 | 0.320 | 0.002 | 0.009 |
| 2–5 cm | 0.020 | 0.642 | 0.118 | 0.026 |
| 5–10 cm | 0.038 | 0.604 | 0.406 | 0.843 |
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Figure 1.
Sampling design showing eight stations along four isobaths (400 m, 700 m, 1000 m and 1300 m) in Almirante Câmara Canyon (CANYON) and on the adjacent open slope (SLOPE).
Figure 1.
Sampling design showing eight stations along four isobaths (400 m, 700 m, 1000 m and 1300 m) in Almirante Câmara Canyon (CANYON) and on the adjacent open slope (SLOPE).
Figure 2.
Mean richness (number of taxa) of meiofauna in the canyon and slope habitats. (A) 400 m, (B) 700 m, (C) 1000 m, (D) 1300 m. Error bars represent the standard deviations.
Figure 2.
Mean richness (number of taxa) of meiofauna in the canyon and slope habitats. (A) 400 m, (B) 700 m, (C) 1000 m, (D) 1300 m. Error bars represent the standard deviations.
Figure 3.
Relative abundances of nematodes, copepods and “other” (less abundant) groups in each habitat: (A) canyon, (B) adjacent open slope.
Figure 3.
Relative abundances of nematodes, copepods and “other” (less abundant) groups in each habitat: (A) canyon, (B) adjacent open slope.
Figure 4.
Rare meiofaunal taxa reported in the meiofaunal assemblages at all investigated stations after removal of the dominant taxa (Nematoda and Copepoda) in the two habitats: (A) surface layer, (B) subsurface layer, (C) deep layer.
Figure 4.
Rare meiofaunal taxa reported in the meiofaunal assemblages at all investigated stations after removal of the dominant taxa (Nematoda and Copepoda) in the two habitats: (A) surface layer, (B) subsurface layer, (C) deep layer.
Figure 5.
Mean densities (ind. 10 cm−2) of total meiofauna in the canyon and on the adjacent open slope by isobath: (A,B) 400 m, (C,D) 700 m, (E,F) 1000 m, (G,H) 1300 m. Error bars: standard error.
Figure 5.
Mean densities (ind. 10 cm−2) of total meiofauna in the canyon and on the adjacent open slope by isobath: (A,B) 400 m, (C,D) 700 m, (E,F) 1000 m, (G,H) 1300 m. Error bars: standard error.
Figure 6.
Multidimensional analysis (nMDS) based on the Bray–Curtis similarity index, as derived from square root-transformed density values of meiofaunal groups: (A) 0–2 cm, (B) 2–5 cm, (C) 5–10 cm. Solid and hollow symbols represent adjacent open slopes and canyons, respectively. The different bathymetric sampling stations are represented by different symbols (triangle: 400 m, square: 700 m, circle: 1000 m and inverted triangle: 1300 m).
Figure 6.
Multidimensional analysis (nMDS) based on the Bray–Curtis similarity index, as derived from square root-transformed density values of meiofaunal groups: (A) 0–2 cm, (B) 2–5 cm, (C) 5–10 cm. Solid and hollow symbols represent adjacent open slopes and canyons, respectively. The different bathymetric sampling stations are represented by different symbols (triangle: 400 m, square: 700 m, circle: 1000 m and inverted triangle: 1300 m).
Table 1.
Results of the three-way PERMANOVA performed for meiofaunal total density, richness, meiofaunal assemblage and rare taxa. Significant p-values are bolded.
Table 1.
Results of the three-way PERMANOVA performed for meiofaunal total density, richness, meiofaunal assemblage and rare taxa. Significant p-values are bolded.
| Factors/Variables | Richness | Density | Assemblage | Rare Taxa | |
|---|---|---|---|---|---|
| HA (1, 143) | MS | 23.3 | <0.001 | 4090.2 | 4401.8 |
| pseudo-F | 3.82 | 23.46 | 8.05 | 3.09 | |
| p (perm) | 0.0543 | 0.0001 | 0.0001 | 0.0011 | |
| ISO (3, 143) | MS | 1.9 | <0.001 | 2969.3 | 4087.4 |
| pseudo-F | 0.31 | 16.22 | 5.84 | 2.87 | |
| p (perm) | 0.8168 | 0.0001 | 0.0001 | 0.0001 | |
| LAY (2, 143) | MS | 558.2 | <0.001 | 40735.0 | 43243.0 |
| pseudo-F | 91.32 | 36.39 | 80.18 | 30.33 | |
| p (perm) | 0.0001 | 0.0001 | 0.0001 | 0.0001 | |
| PD (1, 143) | MS | 3.4 | <0.001 | 794.3 | 2217.0 |
| pseudo-F | 0.55 | 4.76 | 1.56 | 1.56 | |
| p (perm) | 0.460 | 0.0277 | 0.1617 | 0.1248 | |
| HA × ISO (3, 143) | MS | 3.0 | <0.001 | 1151.4 | 3525.2 |
| pseudo-F | 0.49 | 10.70 | 2.27 | 2.40 | |
| p (perm) | 0.6894 | 0.0001 | 0.0077 | 0.0002 | |
| HA × PD (1, 143) | MS | 28.4 | <0.001 | 1287.2 | 2296.6 |
| pseudo-F | 4.64 | 10.77 | 2.53 | 1.61 | |
| p (perm) | 0.0326 | 0.0005 | 0.0382 | 0.1108 | |
| HA × LAY (2, 143) | MS | 2.0 | <0.001 | 891.2 | 2349.4 |
| pseudo-F | 0.32 | 6.60 | 1.75 | 1.65 | |
| p (perm) | 0.7337 | 0.0007 | 0.0747 | 0.0458 | |
| ISO × PD (3, 143) | MS | 7.2 | <0.001 | 816.3 | 1502.5 |
| pseudo-F | 1.18 | 4.94 | 1.61 | 1.05 | |
| p (perm) | 0.3144 | 0.0014 | 0.0851 | 0.3905 | |
| ISO × LAY (6, 143) | MS | 6.1 | <0.001 | 1636.3 | 2742.8 |
| pseudo-F | 1.00 | 3.38 | 3.22 | 1.92 | |
| p (perm) | 0.4301 | 0.0019 | 0.0001 | 0.0002 | |
| PD × LAY (2, 143) | MS | 5.7 | <0.001 | 416.2 | 2021.4 |
| pseudo-F | 0.93 | 2.74 | 0.8192 | 1.42 | |
| p (perm) | 0.3969 | 0.0584 | 0.5964 | 0.1166 | |
| HA × ISO × PD (3, 143) | MS | 13.1 | <0.001 | 602.5 | 1300.5 |
| pseudo-F | 2.14 | 2.61 | 1.18 | 0.91 | |
| p (perm) | 0.0973 | 0.0500 | 0.2782 | 0.5908 | |
| HA × ISO × LAY (6, 143) | MS | 14.9 | <0.001 | 979.3 | 2584.8 |
| pseudo-F | 2.43 | 2.67 | 1.93 | 1.81 | |
| p (perm) | 0.0285 | 0.0104 | 0.0051 | 0.0005 | |
| HA × PD × LAY (2, 143) | MS | 6.0 | <0.001 | 547.9 | 1870.1 |
| pseudo-F | 0.99 | 7.23 | 1.08 | 1.31 | |
| p (perm) | 0.3666 | 0.0004 | 0.3613 | 0.1763 | |
| IS × PD × LAY (6, 143) | MS | 3.8 | <0.001 | 196.0 | 892.0 |
| pseudo-F | 0.61 | 3.00 | 0.39 | 0.62 | |
| p (perm) | 0.7281 | 0.0027 | 0.9993 | 0.9833 | |
| HA × IS × PD × LAY (6, 143) | MS | 4.2 | <0.001 | 302.1 | 1533.1 |
| pseudo-F | 0.68 | 1.97 | 0.59 | 1.07 | |
| p (perm) | 0.6678 | 0.0622 | 0.9537 | 0.3323 |
Table 2.
Densities (mean ± SE, ind. 10 cm−2) of total meiofauna found by different studies in canyons and their adjacent open-slope areas.
Table 2.
Densities (mean ± SE, ind. 10 cm−2) of total meiofauna found by different studies in canyons and their adjacent open-slope areas.
| Mediterranean Sea [24] | Nazaré Canyon [25] Iberian Margin North Atlantic | Almirante Câmara Canyon Southeast Atlantic | ||||||
|---|---|---|---|---|---|---|---|---|
| Box Corer | Multiple Corer | Box Corer | ||||||
| Depths (m) | Mean ±SE | Depth (m) | Mean ±SE | Depth (m) | Mean ±SE | |||
| Canyon | Adjacent | Canyon | Adjacent | Canyon | Adjacent | |||
| 165 | 1399 ** | 743 ** | 300 | 60 ±25 | 150 ±30 | 400 | 2843 ±603 | 580 ±105 |
| 370 | 1856 ** | 629 ** | 1100 | 250 100 | 110 ±20 | 700 | 527 ±149 | 308 ±60 |
| 990 | * | 611 ** | 2850 | 10 ±2 | * | 1000 | 662 ±269 | 224 ±40 |
| 1220 | * | 383 ** | 4800 | 20 ±5 | 30 ±5 | 1300 | 782 ±183 | 229 ±46 |
* not sampled. ** not available.
Table 3.
Result of pairwise tests for meiofaunal density of HA within HA × PD × LA. Significant p-values are bolded.
Table 3.
Result of pairwise tests for meiofaunal density of HA within HA × PD × LA. Significant p-values are bolded.
| Layer | 2008 | 2009 |
|---|---|---|
| 0–2 cm | 0.0006 | 0.7135 |
| 2–5 cm | 0.0150 | 0.1024 |
| 5–10 cm | 0.0044 | 0.3157 |
Table 4.
Results of Spearman correlation analyses for total meiofauna, nematodes and copepods and environmental variables (mean grain size, carbonates, TOC, chlorophyll a and pheophytin a).
Table 4.
Results of Spearman correlation analyses for total meiofauna, nematodes and copepods and environmental variables (mean grain size, carbonates, TOC, chlorophyll a and pheophytin a).
| Area | Environmental Variables | Total Meiofauna | Copepoda | Nematoda |
|---|---|---|---|---|
| Canyon | Mean grain size (Phi) | −0.01 | −0.29 | 0.01 |
| Carbonates (%) | 0.60 * | 0.71 * | 0.57 * | |
| TOC (%) | 0.22 | 0.33 | 0.21 | |
| Chlorophyll a (μg) | 0.69 * | 0.69 * | 0.67 * | |
| Pheophytin a (μg) | 0.62 * | 0.62 * | 0.60 | |
| Adjacent open slope | Mean grain size (Phi) | −0.38 | −0.89 * | −0.30 |
| Carbonates (%) | 0.40 | 0.87 * | 0.32 | |
| TOC (%) | 0.00 | −0.37 | 0.03 | |
| Chlorophyll a (μg) | 0.28 | 0.47 | 0.24 | |
| Pheophytin a (μg) | 0.39 | 0.47 | 0.36 |
* p < 0.05.
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MDPI and ACS Style
Esteves, A.M.; Oliveira, V.S.; Santos, P.J.P.d.; Maria, T.F.; Wandeness, A.P. Meiofauna from Almirante Câmara Canyon and Its Adjacent Open Slope, Southwest Atlantic Ocean. Coasts 2025, 5, 14. https://doi.org/10.3390/coasts5020014
AMA Style
Esteves AM, Oliveira VS, Santos PJPd, Maria TF, Wandeness AP. Meiofauna from Almirante Câmara Canyon and Its Adjacent Open Slope, Southwest Atlantic Ocean. Coasts. 2025; 5(2):14. https://doi.org/10.3390/coasts5020014
Chicago/Turabian StyleEsteves, André M., Verônica S. Oliveira, Paulo J. P. dos Santos, Tatiana F. Maria, and Adriane P. Wandeness. 2025. "Meiofauna from Almirante Câmara Canyon and Its Adjacent Open Slope, Southwest Atlantic Ocean" Coasts 5, no. 2: 14. https://doi.org/10.3390/coasts5020014
APA StyleEsteves, A. M., Oliveira, V. S., Santos, P. J. P. d., Maria, T. F., & Wandeness, A. P. (2025). Meiofauna from Almirante Câmara Canyon and Its Adjacent Open Slope, Southwest Atlantic Ocean. Coasts, 5(2), 14. https://doi.org/10.3390/coasts5020014
