High Species Richness and Extremely Low Abundance of Cumacean Communities Along the Shelf and Slope of the Gulf of Guinea (West Africa)

The Gulf of Guinea belongs to the most scarcely sampled marine basins in the oceans of the world. We have analyzed diversity and distribution patterns of cumacean communities on the shelf and slope, along the coast of Ghana. The material was collected in October and November of 2012 using a van Veen grab (0.1 m2) on nine transects. Six stations were located at each transect (25, 50, 100, 250, 500, and 1,000 m). Sixty-three species of Cumacea were recorded with Leucon and Eocuma as the most speciose genera, with 12 and eight species, respectively. Comparisons of species richness with literature data pointed that the Ghanaian coast hosts very diverse communities. About 95% of species were new to science, and the number of cumacean species known from the West Africa increased by over 100%. Nevertheless, most of the species had extremely low abundance, 13 singletons and 15 doubletons were found. Mean density of cumaceans was estimated at only 1.5 ind./0.1 m2. Species accumulation curve did not reach the asymptotic level, suggesting undersampling, despite the fact that sampling effort was high (250 samples). The highest species richness was recorded in the inner shelf (25–50 m) and on the slope (1,000 m). Cluster analysis separated shallow water communities from deeper regions on the shelf and upper slope. The most unique species composition was found at 1,000 m. Principal component analysis showed the importance of oxygen, sediments, and human-related disturbance for distribution of cumacean communities. In the shallows, oxygen content and presence of gravel were the most important factors structuring communities. In the deeper bottom areas (250–1,000 m), cumacean fauna was affected by local pollution, mainly by higher concentration of barium, other heavy metals, and THC.publishedVersio

Natural and anthropogenic factors influencing abundance of the benthic macrofauna along the shelf and slope of the Gulf of Guinea, a large marine ecosystem off West Africa

The West African continental margin belongs to the least known areas in terms of the ecology of benthic ecosystems. At the same time, this region is influenced by various threats associated with human activities, including industrialisation and oil excavation. Here, we analyse the abundance and distribution patterns of macrozoobenthic communities along the coast of Ghana. The material was collected in 2012 on nine transects at depths ranging from 25 to 1000 m. Over 200 quantitative samples were collected using a 0.1-m2 van Veen grab. Generally, the mean density of macrozoobenthos decreased gradually from the shallow zone (25 m: 231.4 ± 262.2 ind./0.1 m2) down to bathyal depths (1000 m: 55.4 ± 51.4 ind./0.1 m2), but we observed intermediate scale variability in distribution patterns among the transects along the Ghanaian coast. Analysis of environmental factors showed no evidence of substantial pollution, although levels of hydrocarbons, barium and some other toxic metals show some local increases at particular stations, especially on the continental slope. Cluster analysis based on Bray–Curtis similarity and abundance of higher taxonomic groups of macrofauna yielded five groups of stations, while SIMPER analysis demonstrated that polychaetes and amphipods contributed most significantly to within-group similarity. Canonical Correspondence Analysis demonstrated that PAH, THC and toxic metal levels (Ba, Cd, Pb), as well as oxygen concentration, were the most important factors structuring benthic communities.publishedVersio

Eulalia picta Kinberg, 1866 – tube builder or specialized predator?

Twenty six specimens of the polychaete Eulalia picta were found in fine-grained sand tubes. Material was collected in the Antarctic fjord, Admiralty Bay at the depth of about 100 m. The comparison of tube sediment with the sediment composition at the collection site demonstrated that tubes were created with a high degree of particle selection. Our findings might suggest presence of the tube-building behavior in E. picta or show that this species is a highly specialized predator crawling into the tubes of other sessile polychaetes and uses their tubes as protective cases

Taxonomic surrogacy in monitoring of tropical polychaete communities along the West African continental margin

Efficacy tests of surrogacy measures are a very important element of marine benthic monitoring studies that may be used not only in pollution assessment and protection management but also in conservation planning. This approach is very important in the Large Marine Ecosystems that are influenced by numerous environmental factors and threatened by human activities associated with oil excavation and other types of industry. Here we analysed polychaete communities in the Gulf of Guinea (a poorly studied but highly important centre of marine biodiversity in the tropical East Atlantic) at species, genus and family levels. We demonstrated good efficacy of surrogates (genus- and family-level data) in the assessment of richness, diversity and evenness (Shannon, Simpson, Margalef, Pielou indices) along a 25–1000 m depth gradient. The lowest usefulness of higher taxa surrogates was demonstrated in the analysis of faunistic similarity, such as clustering and Similarity Percentage (SIMPER), based on the Bray-Curtis formula. Canonical Correspondence Analysis (CCA) and generalised linear models (GLM) based on Poisson distribution were also used, and demonstrated that genus-level patterns were relatively similar to those at species level. We recorded a substantial loss of information at the family level (as expressed by the modification of eigenvalues and the statistical significance of the axes, as well as the number of most parsimonious models and the smaller weight of each model). Higher taxa analysis at both genus and family levels failed to identify pollution indicator taxa. Since practical aspects of surrogacy require fast identification of the material, family-level data are the most desirable surrogates. Nevertheless, our data demonstrated that, in the case of clustering and ordination based on large numbers of environmental variables, their usefulness is doubtful and they should be used cautiously in order to avoid reaching biased conclusions

A Paradise for Rare Species: Tanaidacean Fauna of the West African Continental Margin

The benthic ecology of the Gulf of Guinea is critically understudied, and knowledge about the composition and biodiversity of the tanaidacean communities remains lacking. Our analysis of tanaidacean collection from 270 quantitative samples collected using 0.1 m2 van Veen grab along the Ghanaian coast (nine transects, six stations at each transect, 25–1,000 m depth range) reveals a high species richness and very low abundance. The mean density of Tanaidacea across all the samples equals only 0.03 ± 0.55 ind./0.1 m2. A total of 87 tanaidacean species were recorded, of which only three were known for science (3.4%), emphasizing the need for intensified taxonomic effort in this region. Circa 40% of the species were singletons, 98% of the species had a total abundance lower than 10 individuals, and approximately half of the species were found only in one sample. The highest species richness was recorded in the slope (500–1,000 m), despite the elevated levels of barium and hydrocarbons at those depths. This area was also characterized by the most unique species composition. Species accumulation curves did not reach an asymptote, suggesting an undersampling of the area and a great rarity of the species. Results of the canonical correspondence analysis (CCA) and cluster analysis demonstrated a positive influence of oxygen concentration and fluorescence, particularly in the shallow shelf sites (25–50 m), which were characterized by a higher abundance of Tanaidacea. Depth zonation of tanaidacean communities with a division between shallow-water taxa (Leptocheliidae Lang, 1973 and Kalliapseudidae Lang, 1956) through families with wide bathymetric range (Pseudotanaidae Sieg, 1976, Apseudidae Leach, 1814) to the true deep-sea forms (Paranarthrurellidae Błażewicz, Jóźwiak and Frutos, 2019) is also evident. We further discuss the problems associated with multivariate analysis of highly speciose but less abundant taxa

A Paradise for Rare Species: Tanaidacean Fauna of the West African Continental Margin

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Plant–moth community relationships at the degraded urban peat‐bog in Central Europe

Abstract Peatlands have their own, specific insect fauna. They are a habitat not only for ubiquistic but also stenotopic moths that feed on plants limited to wet, acid and oligotrophic habitats. In the past, raised bogs and fens were widely distributed in Europe. This has changed since 20th c. Due to irrigation, modern forestry, and increasing human settlement, peatlands have become isolated islands in an agricultural and urban landscape. Here, we analyze the flora in a degraded bog situated in a large Lodz city agglomeration in Poland in relation to the diversity and composition of moth fauna. Over the last 40 years since the bog has become protected as a nature reserve, birch, willow, and alder shrubs replaced the typical raised bog plant communities due to the decreased water level. The analysis of moth communities sampled in 2012 and 2013 indicates dominance of ubiquistic taxa associated with deciduous wetland forests and rushes. Tyrphobiotic and tyrphophile moth taxa were not recorded. We conclude that the absence of moths typical of bog habitats and the dominance of common, woodland species are associated with hydrological changes, the expansion of trees and brushes over typical bog plant communities, and light pollution

Natural and anthropogenic factors influencing abundance of the benthic macrofauna along the shelf and slope of the Gulf of Guinea, a large marine ecosystem off West Africa

The West African continental margin belongs to the least known areas in terms of the ecology of benthic ecosystems. At the same time, this region is influenced by various threats associated with human activities, including industrialisation and oil excavation. Here, we analyse the abundance and distribution patterns of macrozoobenthic communities along the coast of Ghana. The material was collected in 2012 on nine transects at depths ranging from 25 to 1000 m. Over 200 quantitative samples were collected using a 0.1-m2 van Veen grab. Generally, the mean density of macrozoobenthos decreased gradually from the shallow zone (25 m: 231.4 ± 262.2 ind./0.1 m2) down to bathyal depths (1000 m: 55.4 ± 51.4 ind./0.1 m2), but we observed intermediate scale variability in distribution patterns among the transects along the Ghanaian coast. Analysis of environmental factors showed no evidence of substantial pollution, although levels of hydrocarbons, barium and some other toxic metals show some local increases at particular stations, especially on the continental slope. Cluster analysis based on Bray–Curtis similarity and abundance of higher taxonomic groups of macrofauna yielded five groups of stations, while SIMPER analysis demonstrated that polychaetes and amphipods contributed most significantly to within-group similarity. Canonical Correspondence Analysis demonstrated that PAH, THC and toxic metal levels (Ba, Cd, Pb), as well as oxygen concentration, were the most important factors structuring benthic communities