scholarly journals Reef Flat Community Structure of Atol das Rocas, Northeast Brazil and Southwest Atlantic

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Adriana C. Fonseca ◽  
Roberto Villaça ◽  
Bastiaan Knoppers
Keyword(s):  
Community Structure ◽  
Reef Flat ◽  
Temporal Stability ◽  
Coralline Algae ◽  
Brazilian Coast ◽  
Southwest Atlantic ◽  
Green Macroalgae ◽  
Red Macroalgae ◽  
Sw Atlantic ◽  
Definition Of

This study was conducted during 1999 to 2002 and addresses the community structure and some ecological aspects of the benthic reef flat assemblages of Atol das Rocas, located offshore the NE brazilian coast. It corresponds to the sole atoll of the SW Atlantic, which characterized by a shallow topography and is almost completely built by coralline algae. The turf forming red macroalgaeDigenea simplexand the crustose corallineHydrolithon pachydermumwere the dominant species of the reef flat. The crustose green macroalgaeDictyosphaeria ocellataand the turf forming red macroalgaeGelidiella acerosawere the subdominant species. Biomass values ofD. simplexwere about twice higher than the other species, pointing out to its relevance in the community structure of this reef zone. Biodiversity indices indicated a high equitability within the few species observed and a relative temporal stability of the community structure. Some local spatial variations were found in the community structure of the reef flat zone, enabling the definition of three subhabitats. The patterns of distribution and abundance of the benthic organisms seem to be related to the environmental conditions of the reef flat, such as low water turbulence, lengthy periods of aerial exposure, and low herbivore pressure.

Reef‐building coralline algae from the Southwest Atlantic: filling gaps with the recognition of Harveylithon (Corallinaceae, Rhodophyta) on the Brazilian coast

2019 ◽  
Vol 55 (6) ◽  
pp. 1370-1385
Author(s):  
Iara Oliveira Costa ◽  
Priscila Barreto de Jesus ◽  
Tiana da Silva de Jesus ◽  
Poline dos Santos Souza ◽  
Paulo Antunes Horta ◽  
...  
Keyword(s):  
Coralline Algae ◽  
Brazilian Coast ◽  
Southwest Atlantic

scholarly journals Macroalgae

Encyclopedia ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 177-188
Author(s):  
Leonel Pereira
Keyword(s):  
Carbon Dioxide ◽  
Chlorophyll A ◽  
Red Algae ◽  
Great Variability ◽  
Marine Macroalgae ◽  
Brown Macroalgae ◽  
Green Macroalgae ◽  
Red Macroalgae ◽  
Photosynthetic Organisms ◽  
Green Pigments

What are algae? Algae are organisms that perform photosynthesis; that is, they absorb carbon dioxide and release oxygen (therefore they have chlorophyll, a group of green pigments used by photosynthetic organisms that convert sunlight into energy via photosynthesis) and live in water or in humid places. Algae have great variability and are divided into microalgae, small in size and only visible through a microscope, and macroalgae, which are larger in size, up to more than 50 m (the maximum recorded was 65 m), and have a greater diversity in the oceans. Thus, the term “algae” is commonly used to refer to “marine macroalgae or seaweeds”. It is estimated that 1800 different brown macroalgae, 6200 red macroalgae, and 1800 green macroalgae are found in the marine environment. Although the red algae are more diverse, the brown ones are the largest.

scholarly journals Community structure and carbonate production of a temperate rhodolith bank from Arvoredo Island, southern Brazil

2004 ◽  
Vol 52 (3-4) ◽  
pp. 207-224 ◽  
Author(s):  
Douglas F. M. Gherardi
Keyword(s):  
Community Structure ◽  
Coralline Algae ◽  
Carbonate Content ◽  
Production Rates ◽  
Percentage Cover ◽  
Coralline Red Algae ◽  
Carbonate Production ◽  
Random Dispersal ◽  
Long Run ◽  
Main Bank

A small (100,000 m²) rhodolith bank located at the Arvoredo Marine Biological Reserve (Santa Catarina, Brazil) has been surveyed to determine the main bank components, the community structure, and carbonate production rates. Data from five photographic transects perpendicular to Arvoredo Island shore were complemented with sediment samples and shallow cores, all collected by scuba diving. The main bank component is the unattached, nongeniculate, coralline red algae Lithophyllum sp., used as substrate by the zoanthid Zoanthus sp. Percentage cover of living and dead coralline algae, zoanthids and sediment patches account for nearly 98% of the investigated area. Classification and ordination of samples showed that differences in the proportion of live and dead thalli of Lithophyllum sp. determine the relative abundances of zoanthids. Results also indicate that similarity of samples is high and community gradients are subtle. Significant differences in percentage cover along transects are concentrated in the central portion of the bank. Low carbonate content of sediments from deeper samples suggests low rates of recruitment and dispersal of coralline algae via fragmentation. However, carbonate production of Lithophyllum sp ranging from 55-136.3 g m-2 yr-1 agrees with production rates reported for other temperate settings. In the long run, rhodolith density at Arvoredo Is. is likely to be dependent upon random dispersal of spores and/or fragments from other source areas.

scholarly journals Taxonomic status of two morphotypes of Coryphaena hippurus (Perciformes: Coryphaenidae)

2017 ◽  
Vol 15 (1) ◽  
Author(s):  
Alan Bonner ◽  
Michelle R. Duarte ◽  
Rosa C. C. L. Souza ◽  
Cassiano Monteiro-Neto ◽  
Edson P. Silva
Keyword(s):  
Genetic Variation ◽  
Taxonomic Status ◽  
Brazilian Coast ◽  
Gene Pools ◽  
Fishing Pressure ◽  
Allozyme Electrophoresis ◽  
Coryphaena Hippurus ◽  
Biological Matter ◽  
Electrophoresis Method ◽  
Definition Of

ABSTRACT Two Coryphaena hippurus morphotypes (dourado and palombeta) are found along the Brazilian coast and are considered by Rio de Janeiro’s fisherman and fishmongers as two different species. Furthermore, these morphotypes are commercialized under different values and suffer different fishing pressure. Therefore, a definition of their taxonomic status is an important economic and biological matter. In order to investigate this problem, allozyme electrophoresis method was undertaken for seventeen loci on 117 individuals of C. hippurus sampled at Cabo Frio/RJ (Brazil). The data indicate homogeneity between the morphotypes gene pools. Nevertheless, differences were found for genetic variation among dourado and palombeta, especially due to alcohol dehydrogenase locus. Natural selection hypothesis is discussed in explaining these findings.

scholarly journals Slow Community Development Enhances Abiotic Limitation of Benthic Community Structure in a High Arctic Kelp Bed

2021 ◽  
Vol 8 ◽  
Author(s):  
Christina Bonsell ◽  
Kenneth H. Dunton
Keyword(s):  
Community Structure ◽  
Community Development ◽  
Benthic Community ◽  
Beaufort Sea ◽  
High Arctic ◽  
Coralline Algae ◽  
Physical Factors ◽  
Crustose Coralline Algae ◽  
Benthic Community Structure ◽  
Kelp Bed

We examined the patterns of propagule recruitment to assess the timescale and trajectory of succession and the possible roles of physical factors in controlling benthic community structure in a shallow High Arctic kelp bed in the Beaufort Sea, Alaska. Spatial differences in established epilithic assemblages were evaluated against static habitat attributes (depth, distance from river inputs) and environmental factors (temperature, salinity, current speed, underwater light) collected continuously over 2–6 years. Our measurements revealed that bottom waters remained below freezing (mean winter temperatures ∼−1.8°C) and saline (33–36) with negligible light levels for 8–9 months. In contrast, the summer open water period was characterized by variable salinities (22–36), higher temperatures (up to 8–9°C) and measurable irradiance (1–8 mol photons m–2 day–1). An inshore, near-river site experienced strong, acute, springtime drops in salinity to nearly 0 in some years. The epilithic community was dominated by foliose red algae (47–79%), prostrate kelps (2–19%), and crustose coralline algae (0–19%). Strong spatial distinctions among sites included a positive correlation between cover by crustose coralline algae and distance to river inputs, but we found no significant relationships between multi-year means of physical factors and functional groups. Low rates of colonization and the very slow growth rates of recruits are the main factors that contribute to prolonged community development, which augments the influence of low-frequency physical events over local community structure. Mortality during early succession largely determines crustose coralline algal and invertebrate prevalence in the established community, while kelp seem to be recruitment-limited. On scales > 1 m, community structure varies with bathymetry and exposure to freshwater intrusion, which regulate frequency of primary and physiological disturbance. Colonization rates (means of 3.3–69.9 ind. 100 cm–1 year–1 site–1) were much lower than studies in other Arctic kelp habitats, and likely reflect the nature of a truly High Arctic environment. Our results suggest that community development in the nearshore Beaufort Sea occurs over decades, and is affected by combinations of recruitment limitation, primary disturbance, and abiotic stressors. While seasonality exerts strong influence on Arctic systems, static habitat characteristics largely determine benthic ecosystem structure by integrating seasonal and interannual variability over timescales longer than most ecological studies.

scholarly journals Temporal and between-site variation in helminth communities of bank voles (Myodes glareolus) from N.E. Poland. 1. Regional fauna and component community levels

Parasitology ◽  
2008 ◽  
Vol 135 (8) ◽  
pp. 985-997 ◽  
Author(s):  
J. M. BEHNKE ◽  
A. BAJER ◽  
P. D. HARRIS ◽  
L. NEWINGTON ◽  
E. PIDGEON ◽  
...  
Keyword(s):  
Community Structure ◽  
Temporal Stability ◽  
Similarity Index ◽  
Helminth Fauna ◽  
Myodes Glareolus ◽  
Component Community ◽  
Bank Voles ◽  
Helminth Infections ◽  
Site Variation ◽  
Jaccard's Similarity Index

SUMMARYHelminth infections were studied in bank voles (Myodes glareolus) from 3 woodland sites in N.E. Poland in the late summers of 1999 and 2002, to assess the temporal stability of derived statistics describing the regional helminth fauna and component community structure, and spatial influence on the latter. Regional helminth fauna changed dramatically between the two years, primarily due to a fall in the abundance ofSyphacia petrusewiczibut was partially compensated for by an increase inMesocestoides lineatusandCladotaenia globifera. It was dominated by nematodes overall, but more so in 1999 than in 2002 when larval cestodes were more frequent. Most derived parameters for component community structure varied considerably between sites and the two surveys, the hierarchical order for sites not being maintained between surveys. They were susceptible to the disproportionate influence of three relatively rare, unpredictable species with the greatest overall aggregated distribution among hosts. Jaccard's similarity index was less influenced by the rare species, showing greater stability between sites and across years. In conclusion, temporal variation confounded any site-specific characteristics of the summary measures quantified in this study and their usefulness is therefore restricted to the years in which the surveys were conducted.

scholarly journals Zooplankton Community Response to Seasonal Hypoxia: A Test of Three Hypotheses

Diversity ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 21 ◽  
Author(s):  
Julie E. Keister ◽  
Amanda K. Winans ◽  
BethElLee Herrmann
Keyword(s):  
Community Structure ◽  
Puget Sound ◽  
Temporal Stability ◽  
Zooplankton Community ◽  
Community Response ◽  
Crustacean Zooplankton ◽  
Zooplankton Abundance ◽  
Calanoid Copepods ◽  
Low Oxygen ◽  
Seasonal Hypoxia

Several hypotheses of how zooplankton communities respond to coastal hypoxia have been put forward in the literature over the past few decades. We explored three of those that are focused on how zooplankton composition or biomass is affected by seasonal hypoxia using data collected over two summers in Hood Canal, a seasonally-hypoxic sub-basin of Puget Sound, Washington. We conducted hydrographic profiles and zooplankton net tows at four stations, from a region in the south that annually experiences moderate hypoxia to a region in the north where oxygen remains above hypoxic levels. The specific hypotheses tested were that low oxygen leads to: (1) increased dominance of gelatinous relative to crustacean zooplankton, (2) increased dominance of cyclopoid copepods relative to calanoid copepods, and (3) overall decreased zooplankton abundance and biomass at hypoxic sites compared to where oxygen levels are high. Additionally, we examined whether the temporal stability of community structure was decreased by hypoxia. We found evidence of a shift toward more gelatinous zooplankton and lower total zooplankton abundance and biomass at hypoxic sites, but no clear increase in the dominance of cyclopoid relative to calanoid copepods. We also found the lowest variance in community structure at the most hypoxic site, in contrast to our prediction. Hypoxia can fundamentally alter marine ecosystems, but the impacts differ among systems.

Rapid dissolution of shells of weakly calcified Antarctic benthic macroorganisms indicates high vulnerability to ocean acidification

2009 ◽  
Vol 21 (5) ◽  
pp. 449-456 ◽  
Author(s):  
James B. McClintock ◽  
Robert A. Angus ◽  
Michelle R. Mcdonald ◽  
Charles D. Amsler ◽  
Shane A. Catledge ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Marine Invertebrates ◽  
Experimental Studies ◽  
Coralline Algae ◽  
Coralline Alga ◽  
Compensatory Mechanisms ◽  
Dissolution Rates ◽  
Rapid Dissolution ◽  
Definition Of ◽  
Macroinvertebrate Species

AbstractAntarctic calcified macroorganisms are particularly vulnerable to ocean acidification because many are weakly calcified, the dissolution rates of calcium carbonate are inversely related to temperature, and high latitude seas are predicted to become undersaturated in aragonite by the year 2100. We examined the post-mortem dissolution rates of aragonitic and calcitic shells from four species of Antarctic benthic marine invertebrates (two bivalves, one limpet, one brachiopod) and the thallus of a limpet shell-encrusting coralline alga exposed to acidified pH (7.4) or non-acidified pH (8.2) seawater at a constant temperature of 4°C. Within a period of only 14–35 days, shells of all four species held in pH 7.4 seawater had suffered significant dissolution. Despite calcite being 35% less soluble in seawater than aragonite, there was surprisingly, no consistent pattern of calcitic shells having slower dissolution rates than aragonitic shells. Outer surfaces of shells held in pH 7.4 seawater exhibited deterioration by day 35, and by day 56 there was exposure of aragonitic or calcitic prisms within the shell architecture of three of the macroinvertebrate species. Dissolution of coralline algae was confirmed by differences in weight loss in limpet shells with and without coralline algae. By day 56, thalli of the coralline alga held in pH 7.4 displayed a loss of definition of the conceptacle pores and cracking was evident at the zone of interface with limpet shells. Experimental studies are needed to evaluate whether there are adequate compensatory mechanisms in these and other calcified Antarctic benthic macroorganisms to cope with anticipated ocean acidification. In their absence, these organisms, and the communities they comprise, are likely to be among the first to experience the cascading impacts of ocean acidification.

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