scholarly journals Evidence for a trophic cascade on rocky reefs following sea star mass mortality in British Columbia

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1980 ◽  
Author(s):  
Jessica A. Schultz ◽  
Ryan N. Cloutier ◽  
Isabelle M. Côté
Keyword(s):  
British Columbia ◽  
Trophic Cascade ◽  
Sea Urchins ◽  
Fold Increase ◽  
Mass Mortality ◽  
Strongylocentrotus Droebachiensis ◽  
Population Declines ◽  
Sea Star ◽  
Sea Stars ◽  
Study Sites

Echinoderm population collapses, driven by disease outbreaks and climatic events, may be important drivers of population dynamics, ecological shifts and biodiversity. The northeast Pacific recently experienced a mass mortality of sea stars. In Howe Sound, British Columbia, the sunflower starPycnopodia helianthoides—a previously abundant predator of bottom-dwelling invertebrates—began to show signs of a wasting syndrome in early September 2013, and dense aggregations disappeared from many sites in a matter of weeks. Here, we assess changes in subtidal community composition by comparing the abundance of fish, invertebrates and macroalgae at 20 sites in Howe Sound before and after the 2013 sea star mortality to evaluate evidence for a trophic cascade. We observed changes in the abundance of several species after the sea star mortality, most notably a four-fold increase in the number of green sea urchins,Strongylocentrotus droebachiensis, and a significant decline in kelp cover, which are together consistent with a trophic cascade. Qualitative data on the abundance of sunflower stars and green urchins from a citizen science database show that the patterns of echinoderm abundance detected at our study sites reflected wider local trends. The trophic cascade evident at the scale of Howe Sound was observed at half of the study sites. It remains unclear whether the urchin response was triggered directly, via a reduction in urchin mortality, or indirectly, via a shift in urchin distribution into areas previously occupied by the predatory sea stars. Understanding the ecological implications of sudden and extreme population declines may further elucidate the role of echinoderms in temperate seas, and provide insight into the resilience of marine ecosystems to biological disturbances.

scholarly journals Jenis-Jenis Bintang Laut Dan Bulu Babi (Asteroidea, Echinoidea: Echinodermata) Di Perairan Pulau Cilik, Kepulauan Karimunjawa

2018 ◽  
Vol 21 (1) ◽  
pp. 41
Author(s):  
Retno Hartati ◽  
Endika Meirawati ◽  
Sri Redjeki ◽  
Ita Riniatsih ◽  
Robertus Triaji Mahendrajaya
Keyword(s):  
Sea Urchin ◽  
Sea Urchins ◽  
Habitat Type ◽  
Line Transect ◽  
Sea Star ◽  
Acanthaster Planci ◽  
Sea Stars ◽  
Transect Line ◽  
Linckia Laevigata ◽  
Diadema Setosum

Abstract Types of Star Fish and Sea Urchins (Asteroidea, Echinoidea: Echinodermata) In Cilik Island, Karimunjawa WatersEchinoderms are fundamentally good indicators of health and status of coralline communities in marine waters.  Substrat of  sandy, rububle and coral reefs are good habitat for Asteroidea dan Echinoidea.  This study aim to identify sea star (Asteroidea) and sea urchin (Echinoidea) species from Pulau Cilik waters of Karimunjawa Islands. Asteroidea and Echinoidea observed using the line transect method used, ie subjects within the same distance between the transect and the transect square with observations of 2.5 m on the right and left of transect line line. Morphology, habitat type (substrate & depth) and total number of sea stars and sea urchins at each station were determined. The results showed that Pulau Cilik has six species of Asteroidea (Sea star), ie Linckia laevigata, L. multifora, Neoferdifla ocellata (Family Ophidiasteridae), Luidia alternate (Luidiidae Family), Culcita novaeguineae (Family Oreasteridae) and Acanthaster planci which belongs to Family Acanthasteridae. There were 4 species of Echinoidea Sea urchin) found, i.e. Diadema setosum, D. antillarum, D. savignyi and Echinothrix calamaris, which all were family members of Diadematidae Keywords: Ophidiasteridae, Luidiidae, Oreasteridae, Acanthasteridae, Diadematidae AbstrakEchinodermata pada dasarnya merupakan indikator kesehatan dan status dari terumbu karang di laut. Dasar perairan yang landai dengan substrat pasir, terumbu karang dan pecahan karang yang merupakan habitat bagi hewan jenis Asteroidea dan Echinoidea. Penelitian ini bertujuan untuk mengidentifikasi henis-jenis bitang laut dan bulu babi dari perairan Pulau Cilik, Kepulauan Karimunjawa. Pengamatan Asteroidea dan Echinoidea menggunakan metoda line transect yang dimodifikasi, yaitu mengamati subjek dalam jarak yang sama sepanjang garis transect dan kuadrat transect dengan pengamatan 2,5 m di sebelah kanan dan kiri garis line transect. Morfologi, tipe habitat (substrat & kedalaman) dan jumlah total bintang laut dan bulu babi di tiap stasiun dicatat selanjutnya sampel diidentifikasi berdasarkan ciri morfologi tersebut. Hasil penelitian menunjukkan bahwa di perairan Pulau Cilik ditemukan enam spesies Asteroidea (Bintang Laut), yaitu Linckia laevigata, L. multifora, Neoferdifla ocellata (Famili Ophidiasteridae), Luidia alternate (Famili Luidiidae), Culcita novaeguineae (Famili Oreasteridae) dan Acanthaster planci yang termasuk dalam Famili Acanthasteridae. Species Echinoidea (Bulu Babi) ditemukan 4 spesies  Diadema setosum, D. antillarum, D. savignyi dan Echinothrix calamaris  semua anggota famili Diadematidae.Kata kunci : Ophidiasteridae, Luidiidae, Oreasteridae, Acanthasteridae, Diadematidae

Rate of natural mortality in the sea star Archaster angulatus (Echinodermata: Asteroidea)

2017 ◽  
Vol 98 (7) ◽  
pp. 1689-1693
Author(s):  
John K. Keesing
Keyword(s):  
Size Structure ◽  
Sea Urchins ◽  
Maximum Size ◽  
Life History Strategies ◽  
Natural Mortality ◽  
Sea Star ◽  
Sea Stars ◽  
Instantaneous Rate ◽  
Peak Abundance ◽  
Size At Age

The population size structure from a total of 876 individuals, together with published values of growth rate, maximum size and size at age were used to estimate an instantaneous rate of natural mortality (M) of 0.46–0.59 year−1 in a population of the sea star Archaster angulatus from south-western Australia. Peak abundance (17%) of all animals sampled was 105–109 mm arm radius (means of 4.2–4.8 years of age) and only one per cent of sea stars are predicted to live beyond 8 years in the population studied. There are few comparable studies on sea stars but when compared with rates of natural mortality in other echinoderms (sea urchins), A. angulatus is intermediate among species which exhibit the extremes of life history strategies, that is, those which grow very rapidly and may live just two years or less and those with very slow growth rates and which may live for decades.

scholarly journals Reciprocal abundance shifts of the intertidal sea stars, Evasterias troschelii and Pisaster ochraceus , following sea star wasting disease

2019 ◽  
Vol 286 (1901) ◽  
pp. 20182766 ◽  
Author(s):  
Sharon W. C. Kay ◽  
Alyssa-Lois M. Gehman ◽  
Christopher D. G. Harley
Keyword(s):  
Indirect Effects ◽  
Interference Competition ◽  
Disease Outbreaks ◽  
Ecological Communities ◽  
Population Declines ◽  
Sea Star ◽  
Sea Stars ◽  
Wasting Disease ◽  
Field Surveys ◽  
Pisaster Ochraceus

Disease emergence occurs within the context of ecological communities, and disease driven declines in host populations can lead to complex direct and indirect ecological effects. Varying effects of a single disease among multiple susceptible hosts could benefit relatively resistant species. Beginning in 2013, an outbreak of sea star wasting disease (SSWD) led to population declines of many sea star species along the west coast of North America. Through field surveys and laboratory experiments, we investigated how and why the relative abundances of two co-occurring sea star species, Evasterias troschelii and Pisaster ochraceus , shifted during the ongoing wasting epidemic in Burrard Inlet, British Columbia, Canada. We hypothesized that Evasterias is competitively inferior to Pisaster but more resistant to SSWD. Thus, we predicted that SSWD-induced declines of Pisaster could mitigate the negative effects of SSWD on Evasterias , as the latter would experience competitive release. We document shifts in sea star abundance from 2008–2017: Pisaster abundance and mean size declined during the outbreak, while Evasterias abundance increased from relatively rare to numerically dominant within the intertidal. When exposed to symptomatic sea stars, Pisaster and Evasterias both showed signs of SSWD, but transmission and susceptibility was lower in Evasterias. Despite diet overlap documented in our field surveys, Evasterias was not outcompeted by Pisaster in laboratory trails conducted with the relatively small Pisaster available after the outbreak. Interference competition with larger Pisaster , or prey exploitation by Pisaster during the summer when Evasterias is primarily subtidal, may explain the rarity of Evasterias prior to Pisaster declines. Our results suggest that indirect effects mediated by competition can mask some of the direct effects of disease outbreaks, and the combination of direct and indirect effects will determine the restructuring of a community after disturbance.

scholarly journals The Use of Larval Sea Stars and Sea Urchins in the Discovery of Shared Mechanisms of Metazoan Whole-Body Regeneration

Genes ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 1063
Author(s):  
Andrew Wolff ◽  
Veronica Hinman
Keyword(s):  
Sea Urchin ◽  
Sea Urchins ◽  
Whole Body ◽  
Life Stages ◽  
Sea Star ◽  
Sea Stars ◽  
Regenerative Capacity ◽  
New Models ◽  
Ability To Regenerate ◽  
New System

The ability to regenerate is scattered among the metazoan tree of life. Further still, regenerative capacity varies widely within these specific organisms. Numerous organisms, all with different regenerative capabilities, have been studied at length and key similarities and disparities in how regeneration occurs have been identified. In order to get a better grasp on understanding regeneration as a whole, we must search for new models that are capable of extensive regeneration, as well as those that have been under sampled in the literature. As invertebrate deuterostomes, echinoderms fit both of these requirements. Multiple members regenerate various tissue types at all life stages, including examples of whole-body regeneration. Interrogations in two highly studied echinoderms, the sea urchin and the sea star, have provided knowledge of tissue and whole-body regeneration at various life stages. Work has begun to examine regeneration in echinoderm larvae, a potential new system for understanding regenerative mechanisms in a basal deuterostome. Here, we review the ways these two animals’ larvae have been utilized as a model of regeneration.

scholarly journals The development and neuronal complexity of bipinnaria larvae of the sea star Asterias rubens

2021 ◽  
Author(s):  
Hugh F. Carter ◽  
Jeffrey R. Thompson ◽  
Maurice R. Elphick ◽  
Paola Oliveri
Keyword(s):  
Nervous System ◽  
Sea Urchins ◽  
Developmental Studies ◽  
Sea Star ◽  
Asterias Rubens ◽  
Sea Stars ◽  
Experimental Systems ◽  
Developmental Progression ◽  
Staining Methods ◽  
Molecular Anatomy

AbstractFree-swimming planktonic larvae are a key stage in the development of many marine phyla, and studies of these organisms have contributed to our understanding of major genetic and evolutionary processes. Although transitory, these larvae often attain a remarkable degree of tissue complexity, with well-defined musculature and nervous systems. Amongst the best studied are larvae belonging to the phylum Echinodermata, but with work largely focused on the pleuteus larvae of sea urchins (class Echinoidea). The greatest diversity of larval strategies amongst echinoderms is found in the class Asteroidea (sea-stars), organisms that are rapidly emerging as experimental systems for genetic and developmental studies. However, the bipinnaria larvae of sea stars have only been studied in detail in a small number of species and the full complexity of the nervous system is, in particular, poorly understood. Here we have analysed embryonic development and bipinnaria larval anatomy in the common North Atlantic sea-star Asterias rubens, employing use of a variety of staining methods in combination with confocal microscopy. Importantly, the complexity of the nervous system of bipinnaria larvae was revealed in greater detail than ever before, with identification of at least three centres of neuronal complexity: the anterior apical organ, oral region and ciliary bands. Furthermore, the anatomy of the musculature and sites of cell division in bipinnaria larvae were analysed. Comparisons of developmental progression and molecular anatomy across the Echinodermata provided a basis for hypotheses on the shared evolutionary and developmental processes that have shaped this group of animals. We conclude that bipinnaria larvae appear to be remarkably conserved across ~200 million years of evolutionary time and may represent a strong evolutionary and/or developmental constraint for species utilizing this larval strategy.

Repopulation of the shallow subtidal zone by green sea urchins (Strongylocentrotus droebachiensis) following mass mortality in Nova Scotia, Canada

2005 ◽  
Vol 85 (6) ◽  
pp. 1511-1517 ◽  
Author(s):  
Sheanna M. Brady ◽  
Robert E. Scheibling
Keyword(s):  
Sea Urchins ◽  
Disease Outbreak ◽  
Mass Mortality ◽  
Strongylocentrotus Droebachiensis ◽  
Subtidal Zone ◽  
Test Diameter ◽  
Lower Margin ◽  
Primary Means ◽  
Kelp Bed ◽  
Shallow Subtidal

Repopulation by green sea urchins Strongylocentrotus droebachiensis of a steeply sloping rock bottom was monitored at a wave-exposed headland (Chebucto Head) following a disease outbreak that caused mass mortality in September 1999. Density and size of urchins were sampled in four depth strata: at 8–10 m in an urchin grazing aggregation (front) along the lower margin of a kelp bed, at 12 m and 16 m on a bedrock ramp, and at 24 m on a cobble and boulder field where urchins were unaffected by the disease. Shoreward migration of adults along the ramp from the surviving population at 24 m was the primary means of repopulation, which was augmented by recruitment via planktonic larvae. At 16 m, urchin density stabilized (at ∼50 urchins m−2) within six months of the die-off while repopulation at 12 m took more than eight months. A grazing front of large urchins (40–60 mm, test diameter) had formed along the lower edge of a kelp bed by January 2002, which reached densities of up to 284 urchins m−2. Video surveys at Chebucto Head and two adjacent locations of similar bathymetry revealed an extensive urchin population between 25 and 55 m depth, with a mean density on rocky substrata of 73 urchins m−2.

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