scholarly journals Depletion of coastal predatory fish sub-stocks coincided with the largest sea urchin grazing event observed in the NE Atlantic

AMBIO ◽  
2020 ◽  
Vol 50 (1) ◽  
pp. 163-173 ◽  
Author(s):  
Kjell Magnus Norderhaug ◽  
Kjell Nedreaas ◽  
Mats Huserbråten ◽  
Even Moland
Keyword(s):  
Sea Urchin ◽  
Sea Urchins ◽  
Local Population ◽  
Population Connectivity ◽  
Strongylocentrotus Droebachiensis ◽  
Predatory Fish ◽  
Ne Atlantic ◽  
Laminaria Hyperborea ◽  
Fish Stocks ◽  
Coastal Fisheries

AbstractIn this contribution, we propose fishery driven predator release as the cause for the largest grazing event ever observed in the NE Atlantic. Based on the evolving appreciation of limits to population connectivity, published and previously unpublished data, we discuss whether overfishing caused a grazer bloom of the sea urchin (Strongylocentrotus droebachiensis) resulting in overgrazing of more than 2000 km2 kelp (Laminaria hyperborea) forest along Norwegian and Russian coasts during the 1970 s. We show that coastal fisheries likely depleted predatory coastal fish stocks through modernization of fishing methods and fleet. These fish were important predators on urchins and the reduction coincided with the urchin bloom. From this circumstantial evidence, we hypothesize that coastal predatory fish were important in regulating sea urchins, and that a local population dynamics perspective is necessary in management of coastal ecosystems.

Evidence for Association of Vibrio Echinoideorum with Tissue Necrosis on Body Shell of the Green Sea Urchin Strongylocentrotus Droebachiensis

2021 ◽  
Author(s):  
Jonathan Hira ◽  
Klara Stensvåg
Keyword(s):  
Sea Urchin ◽  
Virulence Genes ◽  
Vibrio Vulnificus ◽  
Sea Urchins ◽  
Opportunistic Pathogen ◽  
Significant Degree ◽  
Strongylocentrotus Droebachiensis ◽  
Host Immune System ◽  
Progressive Development ◽  
Green Sea Urchin

Abstract “Sea urchin lesion syndrome” is known as sea urchins disease with the progressive development of necrotic epidermal tissue and loss of external organs, including appendages on the outer body surface. Recently, a novel strain, Vibrio echinoideorum has been isolated from the lesions of green sea urchin (Strongylocentrotus droebachiensis), an economically important mariculture species in Norway. V. echinoideorum has not been reported elsewhere in association of with green sea urchin lesion syndrome. Therefore, in this study, an immersion based bacterial challenge experiment was performed to expose sea urchins (wounded and non-wounded) to V. echinoideorum, thereby mimicking a nearly natural host-pathogen interaction under controlled conditions. This infection experiment demonstrated that only the injured sea urchins developed the lesion to a significant degree when exposed to V. echinoideorum. Pure cultures of the employed bacterial strain was recovered from the infected animals and its identity was confirmed by the MALDI-TOF MS spectra profiling. Additionally, the hemolytic phenotype of V. echinoideorum substantiated its virulence potential towards the host, and this was also supported by the cytolytic effect on red spherule cells of sea urchins. Furthermore, the genome sequence of V. echinoideorum was assumed to encode potential virulence genes and were subjected for in silico comparison with the established virulence factors of Vibrio vulnificus and Vibrio tasmaniensis. This comparative virulence profile provided novel insights about virulence genes and their putative functions related to chemotaxis, adherence, invasion, evasion of the host immune system, and damage of host tissue and cells. Thus, it supports the pathogenicity of V. echinoideorum. In conclusion, the interaction of V. echinoideorum with injured sea urchins appears to be essential for the development of lesion syndrome and therefore, revealing its potentiality as an opportunistic pathogen.

Geographic and environmental factors affecting the distribution of kelp beds and barren grounds and changes in biota associated with kelp reduction at sites along the Norwegian coast

1997 ◽  
Vol 54 (12) ◽  
pp. 2872-2887 ◽  
Author(s):  
Knut Sivertsen
Keyword(s):  
Environmental Factors ◽  
Sea Urchins ◽  
Strongylocentrotus Droebachiensis ◽  
The Arctic ◽  
Laminaria Hyperborea ◽  
Factors Affecting ◽  
Kelp Beds ◽  
The Mean ◽  
Transition Areas ◽  
Barren Grounds

Sites at 244 locations along the west and north Norwegian coasts were investigated to evaluate whether kelp (Laminaria hyperborea) beds had been overgrazed by the sea urchins Strongylocentrotus droebachiensis and Echinus esculentus in the years 1981-1992. Barren ground communities were found in sheltered and moderately wave-exposed areas mainly in the inner and middle archipelago from Nordmøre (63°N) northwards. Densities of large-sized (adult and intermediate) L. hyperborea were 20.7 individuals ·m-2 in kelp beds and 9.7 individuals ·m-2 in transition areas. Juvenile Laminaria spp. were present at densities of 23.9 individuals ·m-2 in kelp beds, 3.6 individuals ·m-2 in transition areas, 0.0 individuals ·m-2 in barren grounds, and 59.1 individuals ·m-2 in kelp-harvested locations. Both the densities and the mean size of S. droebachiensis in barren grounds decreased northwards. The mean densities were 52.2 and 26.1 individuals ·m-2 for the areas south and north of the Arctic Circle, respectively. Multivariate analysis (CANOCO) showed that seven ``environmental'' factors (i.e., kelp depth gradient, distance (latitude), time of sampling, nematode infection in S. droebachiensis, wave exposure, coastal gradient, and substratum) contributed significantly to variability in the distribution of kelp beds and barren grounds. Species in hard-bottom communities in shallow waters could be divided into three distinct BIOTA.

Effect of unidirectional water currents on displacement behaviour of the green sea urchin Strongylocentrous droebachiensis

2013 ◽  
Vol 93 (7) ◽  
pp. 1923-1928 ◽  
Author(s):  
Bryan L. Morse ◽  
Heather L. Hunt
Keyword(s):  
Sea Urchin ◽  
Sea Urchins ◽  
Flow Speed ◽  
Strongylocentrotus Droebachiensis ◽  
Movement Speed ◽  
Water Current ◽  
Flume Experiments ◽  
Water Currents ◽  
Green Sea Urchin ◽  
The Impact

Sea urchins can have important ecological effects on benthic communities through their aggregation and feeding behaviour. Urchin movement has been demonstrated to be negatively affected by wave action, but the impact of unidirectional tidal currents on urchin movement has not been investigated. This study examines the effect of unidirectional water velocity on the direction of displacement and movement rate of the green sea urchin, Strongylocentrotus droebachiensis. In laboratory flume experiments there was a clear effect of water currents on the displacement of sea urchins. At speeds ≤30 cm s−1 urchins moved across the current in a downstream direction, but at speeds of ≥36 cm s−1 the urchins switched directions by more than 90° and moved across the current in an upstream direction. There was a significant effect of flow speed on urchin movement speed, with urchin movement speed decreasing as water current speed increased.

scholarly journals The challenge of managing the commercial harvesting of the sea urchin Paracentrotus lividus: advanced approaches are required

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10093
Author(s):  
Simone Farina ◽  
Maura Baroli ◽  
Roberto Brundu ◽  
Alessandro Conforti ◽  
Andrea Cucco ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Sea Urchin ◽  
Sea Urchins ◽  
Paracentrotus Lividus ◽  
Current Speed ◽  
Predatory Fish ◽  
Bottom Current ◽  
Environmental Constraints ◽  
Calcareous Rock ◽  
Commercial Size

Sea urchins act as a keystone herbivore in marine coastal ecosystems, regulating macrophyte density, which offers refuge for multiple species. In the Mediterranean Sea, both the sea urchin Paracentrotus lividus and fish preying on it are highly valuable target species for artisanal fisheries. As a consequence of the interactions between fish, sea urchins and macrophyte, fishing leads to trophic disorders with detrimental consequences for biodiversity and fisheries. In Sardinia (Western Mediterranean Sea), regulations for sea urchin harvesting have been in place since the mid 90s. However, given the important ecological role of P. lividus, the single-species fishery management may fail to take into account important ecosystem interactions. Hence, a deeper understanding of population dynamics, their dependance on environmental constraints and multispecies interactions may help to achieve long-term sustainable use of this resource. This work aims to highlight how sea urchin population structure varies spatially in relation to local environmental constraints and species interactions, with implications for their management. The study area (Sinis Peninsula, West Sardinia, Italy) that includes a Marine Reserve was divided into five sectors. These display combinations of the environmental constraints influencing sea urchin population dynamics, namely type of habitat (calcareous rock, granite, basalt, patchy and continuous meadows of Posidonia oceanica), average bottom current speed and predatory fish abundance. Size-frequency distribution of sea urchins under commercial size (<5 cm diameter size) assessed during the period from 2004 to 2007, before the population collapse in 2010, were compared for sectors and types of habitat. Specific correlations between recruits (0–1 cm diameter size) and bottom current speeds and between middle-sized sea urchins (2–5 cm diameter size) and predatory fish abundance were assessed. Parameters representing habitat spatial configuration (patch density, perimeter-to-area ratio, mean patch size, largest patch index, interspersion/juxtaposition index) were calculated and their influence on sea urchin density assessed. The density of sea urchins under commercial size was significantly higher in calcareous rock and was positively and significantly influenced by the density and average size of the rocky habitat patches. Recruits were significantly abundant in rocky habitats, while they were almost absent in P. oceanica meadows. The density of middle-sized sea urchins was more abundant in calcareous rock than in basalt, granite or P. oceanica. High densities of recruits resulted significantly correlated to low values of average bottom current speed, while a negative trend between the abundance of middle-sized sea urchins and predatory fish was found. Our results point out the need to account for the environmental constraints influencing local sea urchin density in fisheries management.

Sea Urchins in the Saint Lawrence Estuary: Their Abundance, Size-Structure, and Suitability for Commercial Exploitation

1983 ◽  
Vol 40 (4) ◽  
pp. 474-486 ◽  
Author(s):  
John H. Himmelman ◽  
Yves Lavergne ◽  
Fritz Axelsen ◽  
André Cardinal ◽  
Edwin Bourget
Keyword(s):  
Growth Rate ◽  
Shallow Water ◽  
Sea Urchin ◽  
Size Structure ◽  
Sea Urchins ◽  
Strongylocentrotus Droebachiensis ◽  
Lawrence Estuary ◽  
Algal Abundance ◽  
Ice Conditions ◽  
Intermediate Size

Quantitative transects were made at nine locations along the Saint Lawrence Estuary, Québec, to examine changes in the abundance and size-structure of populations of the green sea urchin, Strongylocentrotus droebachiensis, in relation to the estuarine gradient. Near the seaward extremity of the estuary, sea urchin densities are very high and small urchins are particularly abundant in shallow water. In contrast, midway up the estuary, small urchins are scarce in shallow water, probably because they cannot tolerate the periodic drops in surface salinities which occur there. Where urchin densities are high, urchin grazing severely limits algal production, and because of low algal food availability, the urchin growth rate is exceedingly low. In the Upper Estuary, urchin numbers are low and no urchins are found near the surface. There is feeble recruitment of urchins, and the near absence of urchins of intermediate size suggests that there is a high probability that juveniles are killed before they reach intermediate size. The urchin growth rate is accelerated because of the abundance of algae present, and below 10 m deep some juveniles survive through the intermediate size range. After they reach 40–50 mm in diameter, they can move up to the 2- to 10-m-depth zone and can tolerate the periods of hypo-osmotic conditions which occur there. Suitable populations for commercial use are most likely found where salinity or winter ice conditions reduce urchin numbers to a level permitting greater algal abundance and an elevated somatic and gonadal growth of the remaining urchins.

Effects of the parasitic nematode Echinomermella matsi on growth and survival of its host, the sea urchin Strongylocentrotus droebachiensis

1999 ◽  
Vol 77 (1) ◽  
pp. 139-147 ◽  
Author(s):  
Audun Stien
Keyword(s):  
Population Dynamics ◽  
Sea Urchin ◽  
Parasitic Nematode ◽  
Sea Urchins ◽  
Strongylocentrotus Droebachiensis ◽  
Probability Models ◽  
Negative Effects ◽  
Growth And Survival ◽  
Host Growth ◽  
Reproductive Rates

It has been suggested that the parasitic nematode Echinomermella matsi significantly affects the population dynamics of its host, the sea urchin Strongylocentrotus droebachiensis. The effects of infection on both host fecundity and host survival may be of importance. The fecundity of sea urchins is related to their size. Negative effects of infection on host growth will therefore reduce reproductive rates. I estimated the effect of infection on host growth and survival in two naturally infected wild sea urchin populations using a capture-mark-recapture approach. Infected and uninfected sea urchins were captured and marked with unique tags or recaptured seven times from June 1994 to September 1996. The increment in the diameter of marked sea urchins between captures was used to measure sea urchin growth. The effect of E. matsi infection on host growth was small. Mortality rates were estimated using survival probability models based on the methodology developed by Cormack, Jolly, and Seber. The effect of infection on host survival was pronounced, with estimated sea urchin life expectancies reduced by 33-86% by E. matsi infection. This suggests that E. matsi may affect the population dynamics of S. droebachiensis significantly through the effect on host survival.

Seaweeds, Sea Urchins, and Lobsters: A Reappraisal

1985 ◽  
Vol 42 (12) ◽  
pp. 2061-2072 ◽  
Author(s):  
Robert J. Miller
Keyword(s):  
Sea Urchin ◽  
Sea Urchins ◽  
Stomach Contents ◽  
Homarus Americanus ◽  
Strongylocentrotus Droebachiensis ◽  
Sea Otter ◽  
Feeding Rates ◽  
Growth And Survival ◽  
Definition Of ◽  
Urchin Grazing

A popular hypothesis, that on the south coast of Nova Scotia the green sea urchin (Strongylocentrotus droebachiensis) has been released from control by predators, is critically reviewed. Predator control is given the functional definition of limiting sea urchin grazing sufficient to permit abundant growth of seaweed. Of the predators identified, the American lobster (Homarus americanus) is the least likely to have been important in sea urchin control in recent decades. Feeding rates, stomach contents, and field biomass are available for this species. A smaller amount of data available for the rock crab (Cancer irroratus) and benthic feeding fish points to the conclusion that they likewise cannot control urchin populations. Among other temperate sea urchin species the case is strongest for sea otter control of Strongylocentrotus sp. in some areas of the west coast of North America. The formation of sea urchin grazing fronts, a usual step in the destruction of seaweed beds, has been explained as a behavioral response to predators. This may in fact be merely a response to the location of food. Evidence for suspected enhancement of lobster production by seaweeds is equivocal, and comparative field data collected in and out of seaweed beds (e.g. lobster abundance, food, growth, and survival) have not been published.

Atlantic wolffish (Anarhichas lupus L.; Pisces: Anarhichidae) predation on green sea urchins (Strongylocentrotus droebachiensis (O.F. Mull.); Echinodermata: Echinoidea) in eastern Newfoundland

1986 ◽  
Vol 64 (9) ◽  
pp. 1920-1925 ◽  
Author(s):  
D. W. Keats ◽  
D. H. Steele ◽  
G. R. South
Keyword(s):  
Gastrointestinal Tract ◽  
Sea Urchin ◽  
Sea Urchins ◽  
Strongylocentrotus Droebachiensis ◽  
Rocky Subtidal ◽  
Anarhichas Lupus ◽  
The Mean ◽  
Atlantic Wolffish ◽  
Turn Over

The diet of the Atlantic wolffish was studied by examining the contents of the gastrointestinal tracts of 90 individuals collected from the sea urchin dominated rocky subtidal in eastern Newfoundland. Green sea urchins comprised 75% of the overall diet by weight. Horse mussels ranked second but comprised only 9.5% of the diet. The remainder of the diet consisted of several species of invertebrates and fish. The average (over the whole season) wolffish contained 120 g of urchins, equivalent to the biomass of urchins on 0.23 m2 in the middle of the urchin-dominated zone. During April–September, prior to breeding, the average male wolffish contained 174 g of urchins, and the average female contained 85 g of urchins, biomass values representing, respectively, 0.33 and 0.16 m2. Assuming that the contents of the gastrointestinal tract turn over every 3 days, it was calculated that during May through August each wolffish consumes on average 5.29 kg of urchins (males, 7.09 kg; females, 3.50 kg). Based on these figures, a density of 1 wolffish pair per 20 m2 would be required to consume the mean biomass (532 g m−2) of urchins present in the urchin-dominated zone in 1 year.

scholarly journals Observations from the Hydrolysis of the Green Sea Urchin (Strongylocentrotus Droebachiensis)

2021 ◽  
Author(s):  
Runar Gjerp Solstad ◽  
Philip James
Keyword(s):  
Molecular Weight ◽  
Acid Composition ◽  
Sea Urchin ◽  
Sea Urchins ◽  
Strongylocentrotus Droebachiensis ◽  
Sensory Panel ◽  
Green Sea Urchin ◽  
The World ◽  
Northern Atlantic ◽  
Hydrolysis Of

Abstract There is a large amount of co-product generated by the sea urchin fisheries around the world, as well as a growing interest in removing large quantities of undersize and low value sea urchins from barren areas in the northern Atlantic and Pacific coasts. The authors believe there is scope to develop a hydrolysate product from this and this study gives preliminary observations on the characteristics of hydrolysate from the sea urchin Strongylocentrotus droebachiensis. The biochemical composition for S. droebachiensis were; water 64.1%, protein 3.4%, oil 0.9% and ash 29.8%. Amino acid composition, molecular weight distribution, lipid-class and fatty acid composition are also presented. The authors suggest a sensory-panel mapping be undertaken on future sea urchin hydrolysates. Possible uses for the hydrolysate are unclear at this stage but the combination of amino acids and the relatively high levels of Glycine, Aspartic acid, and Glutamic acid should be further investigated.

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