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 Contrasting size and fate of juvenile crown-of-thorns starfish linked to ontogenetic diet shifts

2020 ◽  
Vol 287 (1931) ◽  
pp. 20201052
Author(s):  
Jennifer C. Wilmes ◽  
Andrew S. Hoey ◽  
Morgan S. Pratchett
Keyword(s):  
Population Dynamics ◽  
Body Size ◽  
Coralline Algae ◽  
Phenotypic Traits ◽  
Diet Shift ◽  
Growth And Survival ◽  
Ontogenetic Diet Shift ◽  
Individual Fitness ◽  
Ontogenetic Diet Shifts ◽  
Diet Shifts

Population dynamics of organisms are shaped by the variation in phenotypic traits, often expressed even among individuals from the same cohort. For example, individual variation in the timing of ontogenetic shifts in diet and/or habitat greatly influences subsequent growth and survival of some organisms, with critical effects on population dynamics. Few studies of natural systems have, however, demonstrated that marked phenotypic variation in growth rates or body size among individuals within a modelled cohort is linked to dietary shifts and food availability. Population irruptions of the crown-of-thorns starfish are one of the foremost contributors to the global degradation of coral reefs, but causes of irruptions have been debated for decades. Here we demonstrate, based on extensive field sampling of juvenile starfish ( n = 3532), that marked variation in body size among juvenile starfish is linked to an ontogenetic diet shift from coralline algae to coral. This transition in diet leads to exponential growth in juveniles and is essential for individuals to reach maturity. Because smaller individuals experience higher mortality and growth is stunted on an algal diet, the ontogenetic shift to corallivory enhances individual fitness and replenishment success. Our findings suggest that the availability of coral prey facilitates early ontogenetic diet shifts and may be fundamental in initiating population irruptions.

scholarly journals Putative long distance gene flow of the Crown-of-Thorns Starfish in the Pacific Ocean

2015 ◽  
Author(s):  
Sergio Tusso ◽  
Kerstin Morcinek ◽  
Catherine Vogler ◽  
Peter J Schupp ◽  
Ciemon F Caballes ◽  
...  
Keyword(s):  
Gene Flow ◽  
Genetic Structure ◽  
Pacific Ocean ◽  
Coral Reefs ◽  
Long Distance ◽  
The Pacific ◽  
Tropical Coral ◽  
Population Outbreaks ◽  
Geographical Regions ◽  
The Pacific Ocean

Population outbreaks of the corallivorous crown-of-thorns starfish (COTS), Acanthaster ‘planci’ L., are considered among the most important biological disturbances of tropical coral reefs. A local COTS outbreak, a “primary outbreak”, can lead to so-called “secondary outbreaks” in adjacent coral reefs due to increased larval release and subsequent dispersion. Previous analyses have shown that in the Pacific Ocean, this dispersion may be geographically restricted to certain regions. Guam, an island in the western Pacific region, suffered from several severe COTS outbreaks in the last 50 years, and in this study we tested whether Guam is genetically connected with surrounding long distant regions. We used microsatellites to measure gene flow and genetic structure among 14 localities in the Pacific Ocean. Our results show substantial genetic structure between geographical regions. There was, however, a lack of significant genetic differentiation between localities separated by large geographic distances (e.g., Guam, Kingman Reef and Johnston Atoll) – a finding consistent with the existence of contemporary long distance larval dispersion and the gradual erasing of ancestral signatures of divergence. Our findings highlight the importance of addressing likely triggers of both primary and secondary outbreaks in conservation efforts using highly variable markers that provide enough variance to infer contemporary patterns of gene-flow and allow to implement programs that strive to control the growth and spread of A. ‘planci’ in the Pacific Ocean.

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.

scholarly journals Impact of marine heatwaves for sea turtle nest temperatures

2021 ◽  
Vol 17 (5) ◽  
Author(s):  
Graeme C. Hays ◽  
William J. Chivers ◽  
Jacques-Olivier Laloë ◽  
Charles Sheppard ◽  
Nicole Esteban
Keyword(s):  
Coral Reefs ◽  
Marine Protected Area ◽  
Ecological Impact ◽  
Sea Turtle ◽  
Sandy Beaches ◽  
Extreme Weather Events ◽  
Weather Events ◽  
Model Predictions ◽  
Causality Testing ◽  
Nesting Beaches

There are major concerns about the ecological impact of extreme weather events. In the oceans, marine heatwaves (MHWs) are an increasing threat causing, for example, recent devastation to coral reefs around the world. We show that these impacts extend to adjacent terrestrial systems and could negatively affect the breeding of endangered species. We demonstrate that during an MHW that resulted in major coral bleaching and mortality in a large, remote marine protected area, anomalously warm temperatures also occurred on sea turtle nesting beaches. Granger causality testing showed that variations in sea surface temperature strongly influenced sand temperatures on beaches. We estimate that the warm conditions on both coral reefs and sandy beaches during the MHW were unprecedented in the last 70 years. Model predictions suggest that the most extreme female-biased hatchling sex ratio and the lowest hatchling survival in nests in the last 70 years both occurred during the heatwave. Our work shows that predicted increases in the frequency and intensity of MHWs will likely have growing impacts on sea turtle nesting beaches as well as other terrestrial coastal environments.

scholarly journals Onychophorology, the study of velvet worms, historical trends, landmarks, and researchers from 1826 to 2020 (a literature review)

Uniciencia ◽  
2021 ◽  
Vol 35 (1) ◽  
pp. 210-230
Author(s):  
Julián Monge-Nájera
Keyword(s):  
Costa Rica ◽  
Conservation Status ◽  
Diet Shift ◽  
Mass Extinctions ◽  
Half Century ◽  
Ontogenetic Diet Shift ◽  
Velvet Worms ◽  
History Of ◽  
Experimental Taphonomy ◽  
New Research

Velvet worms, also known as peripatus or onychophorans, are a phylum of evolutionary importance that has survived all mass extinctions since the Cambrian period. They capture prey with an adhesive net that is formed in a fraction of a second. The first naturalist to formally describe them was Lansdown Guilding (1797-1831), a British priest from the Caribbean island of Saint Vincent. His life is as little known as the history of the field he initiated, Onychophorology. This is the first general history of Onychophorology, which has been divided into half-century periods. The beginning, 1826-1879, was characterized by studies from former students of famous naturalists like Cuvier and von Baer. This generation included Milne-Edwards and Blanchard, and studies were done mostly in France, Britain, and Germany. In the 1880-1929 period, research was concentrated on anatomy, behavior, biogeography, and ecology; and it is in this period when Bouvier published his mammoth monograph. The next half-century, 1930-1979, was important for the discovery of Cambrian species; Vachon’s explanation of how ancient distribution defined the existence of two families; DNA and electron microscopy from Brazil; and primitive attempts at systematics using embryology or isolated anatomical characteristics. Finally, the 1980-2020 period, with research centered in Australia, Brazil, Costa Rica, and Germany, is marked by an evolutionary approach: from body and behavior to geographic distribution; the discovery of how they form their adhesive net; the reconstruction of Cambrian onychophoran communities, the first experimental taphonomy; the first country-wide map of conservation status (in Costa Rica); the first model of why they survive in cities; the discovery of new phenomena like food hiding, parental feeding investment, and ontogenetic diet shift; and the birth of a new research branch, onychophoran ethnobiology. While a few names often appear in the literature, most knowledge was produced by a mass of researchers who entered the field only briefly.

scholarly journals Feeding behavior of Costa Rican velvet worms: food hiding, parental feeding investment and ontogenetic diet shift (Onychophora: Peripatidae)

2019 ◽  
Vol 11 (2) ◽  
pp. 85-88
Author(s):  
José Pablo Barquero González ◽  
Alvaro Vega-Hidalgo ◽  
Julián Monge-Nájera
Keyword(s):  
Feeding Behavior ◽  
Costa Rican ◽  
Diet Shift ◽  
Ontogenetic Diet Shift ◽  
Parental Feeding ◽  
Velvet Worms ◽  
First Time

We report, for the first time in onychophorans, food hiding, parental feeding investment and an ontogenetic diet shift two weeks after birth: from the parent’s adhesive used to capture prey, to the prey itself. 

scholarly journals Genetic structure of the crown-of-thorns seastar in the Pacific Ocean, with focus on Guam

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1970 ◽  
Author(s):  
Sergio Tusso ◽  
Kerstin Morcinek ◽  
Catherine Vogler ◽  
Peter J. Schupp ◽  
Ciemon F. Caballes ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Pacific Ocean ◽  
Long Distance ◽  
The Past ◽  
The Pacific ◽  
Tropical Coral ◽  
Population Outbreaks ◽  
Geographical Regions ◽  
The Pacific Ocean ◽  
The Western Pacific

Population outbreaks of the corallivorous crown-of-thorns seastar (COTS),Acanthaster ‘planci’ L., are among the most important biological disturbances of tropical coral reefs. Over the past 50 years, several devastating outbreaks have been documented around Guam, an island in the western Pacific Ocean. Previous analyses have shown that in the Pacific Ocean, COTS larval dispersal may be geographically restricted to certain regions. Here, we assess the genetic structure of Pacific COTS populations and compared samples from around Guam with a number of distant localities in the Pacific Ocean, and focused on determining the degree of genetic structure among populations previously considered to be isolated. Using microsatellites, we document substantial genetic structure between 14 localities from different geographical regions in the Pacific Ocean. Populations from the 14 locations sampled were found to be structured in three significantly differentiated groups: (1) all locations immediately around Guam, as well as Kingman Reef and Swains Island; (2) Japan, Philippines, GBR and Vanuatu; and (3) Johnston Atoll, which was significantly different from all other localities. The lack of genetic differentiation between Guam and extremely distant populations from Kingman Reef and Swains Island suggests potential long-distance dispersal of COTS in the Pacific.

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