scholarly journals Variation in herbivore grazing behavior across Caribbean reef sites

2021 ◽  
Vol 168 (4) ◽  
Author(s):  
Margaret W. Wilson ◽  
Steven D. Gaines ◽  
Adrian C. Stier ◽  
Benjamin S. Halpern
Keyword(s):  
Coral Reefs ◽  
Ecological Impact ◽  
Coral Growth ◽  
Future Research ◽  
Grazing Impact ◽  
Feeding Rates ◽  
Grazing Behavior ◽  
Growth And Survival ◽  
Caribbean Reef ◽  
Ecological Implications

AbstractHerbivorous fish can increase coral growth and survival by grazing down algal competitors. With coral reefs in global decline, maintaining adequate herbivory has become a primary goal for many managers. However, herbivore biomass targets assume grazing behavior is consistent across different reef systems, even though relatively few have been studied. We document grazing behavior of two scarid species in Antigua, Barbuda, and Bonaire. Our analyses show significant differences in intraspecific feeding rates, time spent grazing, and intensity of grazing across sites, which may alter the ecological impact of a given scarid population. We suggest several hypothesized mechanisms for these behavioral variations that would benefit from explicit testing in future research. As managers set targets to enhance herbivory on reefs, it is critical that we understand potential differences in scarid grazing impact. Our findings demonstrate the variability of grazing behavior across different reef sites and call for further investigation of the drivers and ecological implications of these inconsistencies.

Coral defences: the perilous transition of juvenile crown-of-thorns starfish to corallivory

2021 ◽  
Vol 665 ◽  
pp. 115-125
Author(s):  
DJ Deaker ◽  
B Mos ◽  
C Lawson ◽  
SA Dworjanyn ◽  
C Budden ◽  
...  
Keyword(s):  
Coral Reefs ◽  
Recovery Time ◽  
Adult Population ◽  
Ecological Impact ◽  
Diet Shift ◽  
Growth And Survival ◽  
Ontogenetic Diet Shift ◽  
Seed Population ◽  
Tropical Coral ◽  
Population Outbreaks

The transition from the post-settlement herbivorous juvenile to the coral-eating stage of crown-of-thorns starfish (COTS) is a fundamental step to seed population outbreaks that decimate tropical coral reefs. How the highly cryptic juveniles fare during this transition is poorly understood. We show that the juveniles are vulnerable to attack by coral during this ontogenetic diet shift to coral prey. We monitored the condition, growth, and survival of juvenile COTS during the first 3.5 mo on a diet of Acropora sp. In initial encounters, juveniles often withdrew their arms to avoid the defensive nematocysts of the corals. Within the first 67 d of being offered coral, 37.8% of the juveniles experienced various levels of sublethal and lethal damage. Damaged arms were reduced to ~65.4% of the length of an intact arm, but most injured juveniles were able to regenerate their arms with an average predicted recovery time of ~4 mo. Although sublethal damage slowed the growth of injured juveniles, their capacity to regenerate is likely to contribute to the success of this highly prolific species. Despite being the prey of COTS, coral can influence the survival of juveniles, and potentially reduce their ecological impact by prolonging their growth to reproductive maturity, delaying their transition into a coral predator, and thereby hindering recruitment into the adult population.

scholarly journals The Phytopathogen Dickeya dadantii (Erwinia chrysanthemi 3937) Is a Pathogen of the Pea Aphid

2006 ◽  
Vol 72 (3) ◽  
pp. 1956-1965 ◽  
Author(s):  
Anne-Marie Grenier ◽  
Gabrielle Duport ◽  
Sylvie Pagès ◽  
Guy Condemine ◽  
Yvan Rahbé
Keyword(s):  
Acyrthosiphon Pisum ◽  
Ecological Impact ◽  
Sitophilus Oryzae ◽  
Pea Aphid ◽  
Erwinia Chrysanthemi ◽  
Future Research ◽  
Close Relative ◽  
Bacterial Cells ◽  
Dickeya Dadantii ◽  
Phytopathogenic Bacterium

ABSTRACT Dickeya dadantii (Erwinia chrysanthemi) is a phytopathogenic bacterium causing soft rot diseases on many crops. The sequencing of its genome identified four genes encoding homologues of the Cyt family of insecticidal toxins from Bacillus thuringiensis, which are not present in the close relative Pectobacterium carotovorum subsp. atrosepticum. The pathogenicity of D. dadantii was tested on the pea aphid Acyrthosiphon pisum, and the bacterium was shown to be highly virulent for this insect, either by septic injury or by oral infection. The lethal inoculum dose was calculated to be as low as 10 ingested bacterial cells. A D. dadantii mutant with the four cytotoxin genes deleted showed a reduced per os virulence for A. pisum, highlighting the potential role of at least one of these genes in pathogenicity. Since only one bacterial pathogen of aphids has been previously described (Erwinia aphidicola), other species from the same bacterial group were tested. The pathogenic trait for aphids was shown to be widespread, albeit variable, within the phytopathogens, with no link to phylogenetic positioning in the Enterobacteriaceae. Previously characterized gut symbionts from thrips (Erwinia/Pantoea group) were also highly pathogenic to the aphid, whereas the potent entomopathogen Photorhabdus luminescens was not. D. dadantii is not a generalist insect pathogen, since it has low pathogenicity for three other insect species (Drosophila melanogaster, Sitophilus oryzae, and Spodoptera littoralis). D. dadantii was one of the most virulent aphid pathogens in our screening, and it was active on most aphid instars, except for the first one, probably due to anatomical filtering. The observed difference in virulence toward apterous and winged aphids may have an ecological impact, and this deserves specific attention in future research.

Ecological implications of reduced forage quality on growth and survival of sympatric geese

2014 ◽  
Vol 84 (1) ◽  
pp. 284-298 ◽  
Author(s):  
Samantha E. Richman ◽  
James O. Leafloor ◽  
William H. Karasov ◽  
Scott R. McWilliams
Keyword(s):  
Forage Quality ◽  
Growth And Survival ◽  
Ecological Implications

scholarly journals Coral transplantation on a multilevel substrate of Artificial Patch Reefs: effect of fixing methods on the growth rate of two Acropora species

2020 ◽  
Vol 21 (5) ◽  
Author(s):  
M Munasik ◽  
AGUS SABDONO ◽  
AZELIA N. ASSYFA ◽  
DIAH PERMATA WIJAYANTI ◽  
SUGIYANTO SUGIYANTO ◽  
...  
Keyword(s):  
Growth Rate ◽  
Environmental Changes ◽  
Patch Reef ◽  
Concrete Block ◽  
Coral Growth ◽  
Growth And Survival ◽  
Lower Survival Rate ◽  
Shallow Reef ◽  
Patch Reefs ◽  
Central Java

Abstract. Munasik, Sabdono A, Assyfa AN, Wijayanti DP, Sugiyanto, Irwani, Pribadi R. 2020. Coral transplantation on a multilevel substrate of Artificial Patch Reefs: effect of fixing methods on the growth rate of two Acropora species. Biodiversitas 21: 1816-1822. Branching Acropora is generally used in coral transplantation to rehabilitate coral reefs. However, these corals are sensitive to environmental changes. Artificial Patch Reef  (APR) is an artificial structure that provides a multilevel hard substrate. The purpose of the study was to investigate the effectiveness of the APR structure to facilitate the growth and survival of Acropora branching. Two species Acropora aspera and Acropora copiosa were transplanted vertically and horizontally on a modular concrete block in different levels of APR situated in the shallow reef of Panjang Island, Central Java. The results showed that the coral growth rate varied from 96.7 to 346.9 cm3/month, while survival ranged from 30 to 100% after 8 months. Lower survival rate mostly was found in the upper level of APR. The statistical analyses showed that the growth rate of A. copiosa fragment was significantly higher than that of A. aspera  (p<0.05). Moreover, there were also significant differences in the treatments of transplantation method  (p<0.05) to enhance coral growth. However, multilevel substrates were not significantly influenced by coral growth. This study suggested that A. copiosa which has high-level complexity in branching pattern will be selected to apply in shallow reef rehabilitation with transplanted vertically.

scholarly journals THE ECONOMIC IMPACT OF OCEAN ACIDIFICATION ON CORAL REEFS

2012 ◽  
Vol 03 (01) ◽  
pp. 1250002 ◽  
Author(s):  
LUKE M. BRANDER ◽  
KATRIN REHDANZ ◽  
RICHARD S. J. TOL ◽  
PIETER J. H. VAN BEUKERING
Keyword(s):  
Coral Reefs ◽  
Ocean Acidification ◽  
Economic Impact ◽  
Economic Value ◽  
Future Research ◽  
Atmospheric Concentration ◽  
Value Transfer ◽  
Rapid Economic Growth ◽  
Order Of Magnitude ◽  
Coral Reef Area

Because ocean acidification has only recently been recognized as a problem caused by CO2 emissions, impact studies are still rare and estimates of the economic impact are absent. This paper estimates the economic impact of ocean acidification on coral reefs which are generally considered to be economically as well as ecologically important ecosystems. First, we conduct an impact assessment in which atmospheric concentration of CO2 is linked to ocean acidity causing coral reef area loss. Next, a meta-analytic value transfer is applied to determine the economic value of coral reefs around the world. Finally, these two analyses are combined to estimate the economic impact of ocean acidification on coral reefs for the four IPCC marker scenarios. We find that the annual economic impact rapidly escalates over time, because the scenarios have rapid economic growth in the relevant countries and coral reefs are a luxury good. Nonetheless, the annual value in 2100 in still only a fraction of total income, one order of magnitude smaller than the previously estimated impact of climate change. Although the estimated impact is uncertain, the estimated confidence interval spans one order of magnitude only. Future research should seek to extend the estimates presented here to other impacts of ocean acidification and investigate the implications of our findings for climate policy.

scholarly journals Grazing Effects of Fish versus Sea Urchins on Turf Algae and Coral Recruits: Possible Implications for Coral Reef Resilience and Restoration

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Leor Korzen ◽  
Alvaro Israel ◽  
Avigdor Abelson
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Sea Urchins ◽  
Benthic Algae ◽  
Herbivorous Fish ◽  
Grazing Impact ◽  
Turf Algae ◽  
Coral Reef Resilience ◽  
Drastic Increase ◽  
The Impact

Herbivory is an important structuring factor in coral reefs, influencing seaweed abundance, competitive interactions between seaweeds and corals, and coral reef resilience. Despite reports of a drastic increase in the cover of benthic algae and turf dominancy in the coral reefs of Eilat, Red Sea, very little is known about the factors responsible for this phenomenon or the possible effects of herbivory on turf algae and coral recruits. Here, we examine the effects of herbivory by experimentally exposing turf algae and coral recruits to grazing activities of herbivorous fish and sea urchins. Using remote video cameras to document removal of algae and coral spats, we show that the main grazing impact is due to daily grazing by fishes, whereas the significant impact of sea urchins is mainly expressed in their adverse effect on the survival of coral recruits, with a relatively low effect on algal biomass. These findings contribute to our understanding of the factors influencing turf algae establishment and proliferation, and the survival of coral recruits on the coral reefs of Eilat. The clear differences between the impact of herbivorous fish and that of sea urchins, on the Eilat reefs, have critical implications for reef resilience and restoration measures.

scholarly journals The evolution and functional significance of leaf shape in the angiosperms

2011 ◽  
Vol 38 (7) ◽  
pp. 535 ◽  
Author(s):  
Adrienne B. Nicotra ◽  
Andrea Leigh ◽  
C. Kevin Boyce ◽  
Cynthia S. Jones ◽  
Karl J. Niklas ◽  
...  
Keyword(s):  
Functional Significance ◽  
Leaf Shape ◽  
Future Research ◽  
Shape Variation ◽  
Growth And Survival ◽  
Developmental Sequences ◽  
Evolutionary Context ◽  
Biomechanical Constraints ◽  
Flower Form ◽  
Hot Environments

Angiosperm leaves manifest a remarkable diversity of shapes that range from developmental sequences within a shoot and within crown response to microenvironment to variation among species within and between communities and among orders or families. It is generally assumed that because photosynthetic leaves are critical to plant growth and survival, variation in their shape reflects natural selection operating on function. Several non-mutually exclusive theories have been proposed to explain leaf shape diversity. These include: thermoregulation of leaves especially in arid and hot environments, hydraulic constraints, patterns of leaf expansion in deciduous species, biomechanical constraints, adaptations to avoid herbivory, adaptations to optimise light interception and even that leaf shape variation is a response to selection on flower form. However, the relative importance, or likelihood, of each of these factors is unclear. Here we review the evolutionary context of leaf shape diversification, discuss the proximal mechanisms that generate the diversity in extant systems, and consider the evidence for each the above hypotheses in the context of the functional significance of leaf shape. The synthesis of these broad ranging areas helps to identify points of conceptual convergence for ongoing discussion and integrated directions for future research.

Gastrointestinal nematode parasites and the stability and productivity of intensive ruminant grazing systems

1988 ◽  
Vol 321 (1207) ◽  
pp. 541-563 ◽  
Keyword(s):  
Plant Density ◽  
Gastrointestinal Nematode ◽  
Future Research ◽  
Feeding Rates ◽  
Nematode Parasites ◽  
Relevant Field ◽  
Grazing Systems ◽  
The Stability ◽  
Grass Growth ◽  
The Impact

This paper uses mathematical models, describing the transmission dynamics of directly transmitted gastrointestinal nematode parasites of sheep and cattle, to examine the impact of these parasites on the stability and productivity of ruminant grazing systems. Current models of the ecology of grass growth under grazing, and the epidemiology of trichostrongylid nematode parasites of ruminants, are combined in a formulation that captures the general features of the plant - (ruminant) herbivore - parasite interaction. The simplest case, in which herbivore numbers are constant and not food limited (the norm for m any agricultural systems) is considered in detail. T he effect of gastrointestinal parasitism in reducing herbivore feeding rates is shown to act as a potential density-dependent constraint on the parasite’s infection rate. T he process is manifested in the model as a progressive linearization of the relation between herbivore feeding rate and plant density at the parasite equilibrium . This effect acts to stabilize the dynamics of the model grazing system and significantly affects its predictions about the impact of parasite control and the pattern of host productivity. Model predictions are discussed in the light of relevant field observations, and areas for future research are identified.

Feathers in the spotless starling nests: a sexually selected trait?

Behaviour ◽  
2011 ◽  
Vol 148 (11-13) ◽  
pp. 1355-1371 ◽  
Author(s):  
José P. Veiga ◽  
Vicente Polo
Keyword(s):  
Sexual Selection ◽  
Alternative Hypothesis ◽  
Chemical Defence ◽  
Passerine Bird ◽  
Future Research ◽  
Feeding Rates ◽  
Male Display ◽  
Pair Mating ◽  
Spotless Starling ◽  
Second Clutch

AbstractThe carrying of feathers to adorn the nest has been recently described as a female behaviour that indicates quality in a passerine bird — the spotless starling (Sturnus unicolor) —, but the consequences that the variability of this trait may have on breeding success are still unknown. The feather-carrying behaviour is a sexual behaviour that is performed in response to a male display: the carrying of green plants. In this paper we explore whether foreign feathers affect male investment on chick rearing or reinforce the pair mating bonds. The experimental addition of feathers to nests caused an increase in clutch size and a reduction of nestling mortality, although it did not affect feeding rates or the removal of faecal sacs by males or females. Nest feathers did not increase the frequency with which females laid a second clutch in the same nest and with the same male. Thus, our results do not support the sexual selection hypothesis for the evolution of the carrying feathers behaviour. An alternative hypothesis that deserves to be addressed in specifically designed studies is that foreign feathers may be taken to nests as a sort of chemical warfare against nest parasites. The sexual selection and the chemical defence hypotheses are, however, not mutually exclusive and future research should evaluate whether the pre-existence of a behavioural trait arising by natural selection may drive the evolution of a signalling trait.

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