scholarly journals Coral community structure at pooled random sites between Cabritte Horn and White Point in St. John before and after five hurricanes from 1988–2017

2018 ◽  
Author(s):  
Peter Edmunds
Keyword(s):  
Community Structure ◽  
Coral Community ◽  
Before And After ◽  
White Point

scholarly journals Transects, quadrats, or points? What is the best combination to get a precise estimation of a coral community?

2019 ◽  
Author(s):  
Luis M. Montilla ◽  
Emy Miyazawa ◽  
Alfredo Ascanio ◽  
María López-Hernández ◽  
Gloria Mariño-Briceño ◽  
...  
Keyword(s):  
Community Structure ◽  
Coral Reef ◽  
Effect Size ◽  
Standard Error ◽  
Scleractinian Coral ◽  
Statistical Power ◽  
Coral Community ◽  
Sampling Effort ◽  
Precise Estimation

ABSTRACTThe characteristics of coral reef sampling and monitoring are highly variable, with numbers of units and sampling effort varying from one study to another. Numerous works have been carried out to determine an appropriate effect size through statistical power, however, always from a univariate perspective. In this work, we used the pseudo multivariate dissimilarity-based standard error (MultSE) approach to assess the precision of sampling scleractinian coral assemblages in reefs of Venezuela between 2017 and 2018 when using different combinations of number of transects, quadrats and points. For this, the MultSE of 36 sites previously sampled was estimated, using four 30m-transects with 15 photo-quadrats each and 25 random points per quadrat. We obtained that the MultSE was highly variable between sites and is not correlated with the univariate standard error nor with the richness of species. Then, a subset of sites was re-annotated using 100 uniformly distributed points, which allowed the simulation of different numbers of transects per site, quadrats per transect and points per quadrat using resampling techniques. The magnitude of the MultSE stabilized by adding more transects, however, adding more quadrats or points does not improve the estimate. For this case study, the error was reduced by half when using 10 transects, 10 quadrats per transect and 25 points per quadrat. We recommend the use of MultSE in reef monitoring programs, in particular when conducting pilot surveys to optimize the estimation of the community structure.

Effects of forestry activities (clearfelling) on stream macroinvertebrate fauna in south-western Australia

1994 ◽  
Vol 45 (6) ◽  
pp. 963 ◽  
Author(s):  
IO Growns ◽  
JA Davis
Keyword(s):  
Species Richness ◽  
Community Structure ◽  
Western Australia ◽  
Macroinvertebrate Community ◽  
Total Abundance ◽  
Inorganic Solids ◽  
South West ◽  
Before And After ◽  
Stream Macroinvertebrate ◽  
Macroinvertebrate Fauna

The effects of forestry activities on macroinvertebrate community structure were examined in the headwaters of Carey Brook in the south-west of Australia. The fauna at four sites on an upland stream that ran through a logging coupe were compared, before and after clearfelling, with the fauna at four nearby undisturbed sites. Mean species richness and mean total abundance declined at the treatment sites relative to the control sites after the commencement of clearfelling activities. The composition of the macroinvertebrate fauna in the disturbed stream changed in comparison with that in the undisturbed sites after logging started but returned to the pre-logging composition after winter and spring rains had stopped. The observed changes in the macroinvertebrate fauna occurred during the periods of high loads of suspended inorganic solids at the treatment sites. The possible reasons for the observed results are discussed.

scholarly journals Subtidal littering: Indirect effects on soft substratum macrofauna?

2008 ◽  
Vol 9 (2) ◽  
pp. 35 ◽  
Author(s):  
I. AKOUMIANAKI ◽  
P. KONTOLEFAS ◽  
S. KATSANEVAKIS ◽  
A. NICOLAIDOU ◽  
G. VERRIOPOULOS
Keyword(s):  
Community Structure ◽  
Sediment Surface ◽  
Long Run ◽  
Significant Difference ◽  
Before And After ◽  
Soft Substratum ◽  
One Year ◽  
The Impact ◽  
Control Surfaces ◽  
Macrofauna Community

Changes in macrofauna community structure, abundance and species richness were examined both before and one year after the deployment of plastic and glass bottles at littered (litter density: 16 items / 100 m2) and non-littered (control) surfaces at three unimpacted coastal areas of the western Saronikos Gulf (Greece). In parallel, LOI% at the adjacent sediments and changes in the composition of feeding types of the megaepifauna that colonized the litter were examined across treatments. Significant changes in macrofauna community structure were demonstrated between before and after littering. At only one of the sites was there detected a significant difference in macrofauna community structure between control and littered plots after littering. This difference was linked with a significant increase in the abundance of opportunistic polychaete species and LOI% levels in the sediment surface due to the entrapment of macrophytal debris within the littered surface. The study did not show a consistent direct response of macroinfauna community to litter and the associated megafauna. Unlike the megafauna attracted by litter items, soft-substratum macrofauna is less responsive to the addition of novel hard substrates in adjacent sediments. Alternatively, it could be that the impact of littering with small items triggers a macrofauna response detectable in the long-run.

scholarly journals Coral communities condition in varying wave exposure: the gulf of Cazones, Cuba

2016 ◽  
Vol 64 (1) ◽  
pp. 79 ◽  
Author(s):  
Hansel Caballero Aragon ◽  
Pedro M Alcolado ◽  
Néstor Rey-Villiers ◽  
Susana Perera Valderrama ◽  
Juliett González Méndez
Keyword(s):  
Species Richness ◽  
Community Structure ◽  
Marine Protected Area ◽  
Coral Cover ◽  
Coral Community ◽  
Wave Exposure ◽  
Maximum Diameter ◽  
Live Coral ◽  
Coral Mortality ◽  
Coral Communities

Wave exposure can influence community structure and distribution of shallow coral reefs, by affecting organisms both directly and indirectly. To assess the current stony coral community condition under different degrees of wave exposure at a marine protected area of the Gulf of Cazones (SW Cuba), two expeditions were carried out in May 2010 and June 2012. Four sampling sites were sampled at reef crests (1.5 m deep), and twelve at fore-reefs, at 10, 15 and 20 m deep in four geographic locations. Live coral cover, species richness and composition, colony density, and maximum diameter were assessed using the AGRRA 2001 methodology. Multivariate and non-parametric statistics were applied to compare sites. The coral community structure within reef crests was not homogenous. The observed variability of indicators apparently was determined by great coral mortality events resulting from natural disturbances that occurred in the past (hurricanes, bleaching and diseases). Fore-reef coral communities displayed better condition and lower coral mortality than reef crests. Species richness and coral composition varied, while multivariate and statistical methods did not reveal site grouping with regard to wave exposure. The remaining biological condition indicators were similar among sites, except in the most exposed one, where coral cover and coral size were slightly lower. Wave exposure in the gulf of Cazones seemed not to have a significant influence on differences in condition and structure of the assessed coral communities.

scholarly journals Temperature regimes impact coral assemblages along environmental gradients on lagoonal reefs in Belize

2016 ◽  
Author(s):  
Justin H. Baumann ◽  
Joseph E. Townsend ◽  
Travis A. Courtney ◽  
Hannah E. Aichelman ◽  
Sarah W. Davies ◽  
...  
Keyword(s):  
Life History ◽  
Community Structure ◽  
Coral Reefs ◽  
Coral Species ◽  
Environmental Gradients ◽  
Coral Community ◽  
Life History Strategies ◽  
Percent Cover ◽  
Chl A ◽  
Reef System

AbstractCoral reefs are increasingly threatened by global and local anthropogenic stressors such as rising seawater temperature, nutrient enrichment, sedimentation, and overfishing. Although many studies have investigated the impacts of local and global stressors on coral reefs, we still do not fully understand how these stressors influence coral community structure, particularly across environmental gradients on a reef system. Here, we investigate coral community composition across three different temperature and productivity regimes along a nearshore-offshore gradient on lagoonal reefs of the Belize Mesoamerican Barrier Reef System (MBRS). A novel metric was developed using ultra-high-resolution satellite-derived estimates of sea surface temperatures (SST) to classify reefs as exposed to low (lowTP), moderate (modTP), or high (highTP) temperature parameters over 10 years (2003 to 2012). Coral species richness, abundance, diversity, density, and percent cover were lower at highTP sites relative to lowTP and modTP sites, but these coral community traits did not differ significantly between lowTP and modTP sites. Analysis of coral life history strategies revealed that highTP sites were dominated by hardy stress tolerant and fast-growing weedy coral species, while lowTP and modTP sites consisted of competitive, generalist, weedy, and stress-tolerant coral species. Satellite-derived estimates of Chlorophyll-a (chl-a) were obtained for 13-years (2003-2015) as a proxy for primary production. Chl-a concentrations were highest at highTP sites, medial at modTP sites, and lowest at lowTP sites. Notably, thermal parameters correlated better with coral community traits between site types than productivity, suggesting that temperature (specifically number of days above the thermal bleaching threshold) played a greater role in defining coral community structure than productivity on the MBRS. Dominance of weedy and stress-tolerant genera at highTP sites suggests that corals utilizing these two life history strategies may be better suited to cope with warmer oceans and thus may warrant protective status under climate change.

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