scholarly journals Abundance of sedentary consumers and sessile organisms along the wave exposure gradient of subtropical rocky shores of the south-west Atlantic

2010 ◽  
Vol 91 (5) ◽  
pp. 961-967 ◽  
Author(s):  
Ronaldo A. Christofoletti ◽  
Camila K. Takahashi ◽  
Diogo N. Oliveira ◽  
Augusto A.V. Flores
Keyword(s):  
Prey Availability ◽  
Temporal Distribution ◽  
Wave Exposure ◽  
Ecosystem Dynamics ◽  
Rocky Shores ◽  
The South ◽  
Ecological Processes ◽  
Bare Rock ◽  
South West ◽  
Sessile Organisms

Sedentary consumers play an important role on populations of prey and, hence, their patterns of abundance, distribution and coexistence on shores are important to evaluate their potential influence on ecosystem dynamics. Here, we aimed to describe their spatio-temporal distribution and abundance in relation to wave exposure in the intertidal rocky shores of the south-west Atlantic to provide a basis for further understanding of ecological processes in this system. The abundance and composition of the functional groups of sessile organisms and sedentary consumers were taken by sampling the intertidal of sheltered and moderately exposed shores during a period of one year. The sublittoral fringe of sheltered areas was dominated by macroalgae, while the low midlittoral was dominated by bare rock and barnacles. In contrast, filter-feeding animals prevailed at exposed shores, probably explaining the higher abundance of the predator Stramonita haemastoma at these locations. Limpets were more abundant at the midlittoral zone of all shores while sea urchins were exclusively found at the sublittoral fringe of moderately exposed shores, therefore, adding grazing pressure on these areas. The results showed patterns of coexistence, distribution and abundance of those organisms in this subtropical area, presumably as a result of wave action, competition and prey availability. It also brought insights on the influence of top-down and bottom-up processes in this area.

Observations on the ultrastructure of the spermatozoon of two mytilids from the south-west coast of England

1986 ◽  
Vol 66 (2) ◽  
pp. 385-390 ◽  
Author(s):  
A. N. Hodgson ◽  
R. T. F. Bernard
Keyword(s):  
West Coast ◽  
Rocky Shores ◽  
Firm Conclusion ◽  
The South ◽  
Separate Species ◽  
Systematic Status ◽  
South West ◽  
South West Coast

INTRODUCTIONTwo forms of the genus Mytilus, M. edulis L. and M. galloprovincialis Lmk inhabit the rocky shores of Devon and Cornwall (Hepper, 1957). According to Gosling (1984), controversy has existed since 1860 as to whether M. galloprovincialis is a separate species or a subspecies of M. edulis. In a review of the systematic status of M. galloprovincialis, Gosling (1984) analysed the criteria used to identify and classify this form of Mytilus. Gosling did not reach any firm conclusion on the systematic status of these mytilids, but did suggest that the evidence favoured placing M. galloprovincialis as a variety, ecotype or even subspecies of M. edulis.

Defining conservation units in a rich and fragmented flora: implications for the management of genetic resources and evolutionary processes in south-west Australian plants

2000 ◽  
Vol 48 (3) ◽  
pp. 329 ◽  
Author(s):  
David J. Coates
Keyword(s):  
Genetic Structure ◽  
Species Diversity ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Conservation Strategies ◽  
The South ◽  
Conservation Units ◽  
Ecological Processes ◽  
South West ◽  
Australian Flora

The south-west Australian flora shows a diverse array of evolutionary patterns and exceptionally high species diversity. A significant component of this flora consists of relictual species which often have naturally fragmented and geographically restricted distributions. Many of these species appear to apportion significant levels of genetic diversity among populations. Diversity at both the population and species level presents a major challenge to the development of appropriate conservation strategies for this flora. To be effective these strategies should not only aim to preserve current levels of species diversity, but also consider intraspecific variation and the evolutionary and ecological processes associated with the generation and maintenance of that variation. The identification and characterisation of conservation units, based on population genetic structure and phylogeographic patterns within species, provide a useful basis upon which more general conservation principals can be developed for the maintenance of these processes. Population genetic structure and phylogeographic studies are used to show how conservation units can be identified in Lambertia orbifolia, Acacia anomala, Stylidium coroniforme, Stylidium nungarinense and Banksia cuneata, and taxa from a range of other genera. Determining conservation units in these taxa defines not only suitable units for their conservation but also the appropriate geographical scale for management. These findings indicate the potential this approach can have in determining strategies and priorities for the conservation of the south-west Australian flora.

Dynamics of Odontella spp. in the Atlantic Ocean of Nigeria

Nova Hedwigia ◽  
2020 ◽  
Vol 110 (3) ◽  
pp. 227-246
Author(s):  
Medina Omo Kadiri ◽  
Osasere Abike Omoruyi
Keyword(s):  
Atlantic Ocean ◽  
Temporal Distribution ◽  
Marine Phytoplankton ◽  
Distributional Pattern ◽  
Centric Diatom ◽  
The South ◽  
West Region ◽  
South West ◽  
Dry Seasons ◽  
South West Region

Odontella is a planktonic centric diatom widely distributed in saline waters. Although some studies on marine phytoplankton in Nigeria mention the genus, there is a considerable dearth of information on its distribution in the Atlantic Ocean (Nigeria). This paper examined the density, diversity, spatial and temporal distribution of Odontella species in the Atlantic Ocean, in the Bight of Benin and Bight of Bonny (Nigeria). Phytoplankton samples were collected from 10 locations on the stretch of the Atlantic Ocean (Nigeria), in four seasons (dry-wet, wet, wet-dry and dry). Results revealed that eight species of Odontella, namely O. aurita, O. granulata, O. longicruris, O. mobilensis, O. obtusa, O. regia, O. rhombus and O. sinensis occurred in the Atlantic Ocean (Nigeria). The eight Odontella species showed differential distributional pattern, both spatially and temporally. Akwa Ibom location had the highest Odontella abundance in the South-South region while Ondo was highest in the South-West region. Higher Odontella abundance was recorded in the transition seasons (dry-wet and wet-dry seasons) than in the typically wet and dry seasons. The species O. regia was dominant and widely distributed in the South-West region, while O. aurita was dominant in the South-South region. Relatively, the density of O. longicruris was low throughout the Atlantic Ocean (Nigeria) and at all seasons. O. regia and O. sinensis were the most widely distributed species in the Atlantic Ocean (Nigeria) and occurred all through the seasons studied while O. obtusa occurred sparingly throughout all the seasons.

Middle and Late Iron Age Occupation at Cadnam Farm, Alton, Hampshire

2018 ◽  
Vol 73 (1) ◽  
pp. 110-136
Author(s):  
Oliver Good ◽  
Richard Massey
Keyword(s):  
Iron Age ◽  
The South ◽  
Late Iron Age ◽  
South West ◽  
Middle Iron Age

Three individual areas, totalling 0.55ha, were excavated at the Cadnam Farm site, following evaluation. Area 1 contained a D-shaped enclosure of Middle Iron Age date, associated with the remains of a roundhouse, and a ditched drove-way. Other features included refuse pits, a four-post structure and a small post-built structure of circular plan. Area 2 contained the superimposed foundation gullies of two Middle Iron Age roundhouses, adjacent to a probable third example. Area 3 contained a small number of Middle Iron Age pits, together with undated, post-built structures of probable Middle Iron Age date, including a roundhouse and four and six-post structures. Two large boundary ditches extended from the south-west corner of Area 3, and were interpreted as the funnelled entrance of a drove-way. These contained both domestic and industrial refuse of the late Iron Age date in their fills.

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