scholarly journals EVIDENCE OF MASS MORTALITY OF THE LONG-LIVED BIVALVE MERCENARIA STIMPSONI CAUSED BY A CATASTROPHIC TSUNAMI

Radiocarbon ◽  
2021 ◽  
pp. 1-16
Author(s):  
Kaoru Kubota ◽  
Kotaro Shirai ◽  
Naoko Murakami-Sugihara ◽  
Koji Seike ◽  
Masayo Minami ◽  
...  
Keyword(s):  
Mass Mortality ◽  
Individual Species ◽  
Benthic Organisms ◽  
Nuclear Bomb ◽  
Growth Increments ◽  
Sea Bottom ◽  
Northeastern Japan ◽  
Dating Method ◽  
Ecological Importance ◽  
Benthic Ecosystems

ABSTRACT Tsunamis are huge disasters that can significantly damage benthic organisms and the sea-bottom environment in coastal areas. It is of great ecological importance to understand how benthic ecosystems respond to such destructive forces and how individual species are affected. Investigating the effect of such disasters on animals that are seldom caught alive is particularly difficult. Bivalve mollusks are especially suitable for investigating how a tsunami affects coastal benthic species because they preserve an environmental record in their shells that can be extended back in time by crossdating the records of multiple individuals. Here we studied dead shells of Mercenaria stimpsoni, a long-lived clam, and precisely determined the time of death by using nuclear bomb–induced radiocarbon (bomb-14C) and by counting annual growth increments. First, a quasi-continuous, regional bomb-14C record was created by analyzing the shells of 6 live-caught M. stimpsoni individuals. Then 27 dead shells collected from the seafloor of Funakoshi Bay were 14C-dated and analyzed. The results showed that the huge tsunami that struck northeastern Japan on 11 March 2011 caused mass mortality of this bivalve in Funakoshi Bay. Nine of the 27 clams died during the March 2011 tsunami, probably by starvation after burial by tsunami deposits or exposure above the seafloor as a result of sediment liquefaction during the earthquake. The dating method used in this study can help us understand how long-lived marine organisms with low population density are affected by huge natural disasters such as a tsunami.

Responses by benthic organisms to inputs of organic material to the ocean floor: a review

1990 ◽  
Vol 331 (1616) ◽  
pp. 119-138 ◽  
Keyword(s):  
Organic Material ◽  
Euphotic Zone ◽  
Ocean Floor ◽  
Sediment Surface ◽  
Benthic Organisms ◽  
Faecal Pellets ◽  
Reproductive Cycles ◽  
Benthic Ecosystems ◽  
Deposit Feeding ◽  
Northeastern Atlantic

Most of the photosynthetically produced organic material reaching the ocean-floor is transported as settling particles, among which larger particles such as faecal pellets and macroaggregates (marine snow) are particularly important. Recent studies in the northeastern Atlantic have demonstrated that macroaggregates originating from the euphotic zone settle at a rate of approximately 100-150 m d -1 to form a deposit (phytodetritus) on the sediment surface. Bacteria and protozoa (flagellates and foraminifers) rapidly colonize and multiply on phytodetritus, while large deposit feeding animals ingest it. Other inputs, for example Sargassum , wood and vertebrate carcasses, also evoke a rapid response by benthic organisms. However, the taxa that respond depend on the form of the organic material. The intermittent or seasonally pulsed nature of phytodetritus and many other inputs regulate the population dynamics and reproductive cycles of some responding species. These are often opportunists that are able to utilize ephemeral food resources and, therefore, undergo rapid fluctuations in population density. In addition, the patchy distribution of much of the organic material deposited on the ocean-floor probably plays a major role in structuring deep-sea benthic ecosystems.

scholarly journals Physiological effects of hydrocarbons on phytoplankton

1978 ◽  
Author(s):  
Μιχαήλ Καρύδης
Keyword(s):  
Gas Chromatography ◽  
Individual Species ◽  
Physiological Effects ◽  
Marine Diatoms ◽  
Laboratory Cultures ◽  
Oil Concentration ◽  
Ecological Importance ◽  
The Individual ◽  
Photosynthetic Activities ◽  
Paraffin Fraction

The effect of hydrocarbons on phytoplankton has been studied using laboratory cultures of marine diatoms and flagellates. Low oil concentrations ,stimulate photosynthetic activities while high oil concentration« cause inhibition. The concentrations required for both stimulation and toxicity depend on the individual species. The toxic effects become more obvious after a few days due perhaps to the slow penetration of the oils. The toxicity levels are also affected by the presence of organic material in the medium.. Studies on the ultrastructure hasrshown an effect of the paraffin fraction on the cell wall although the external morphology was not affected. Assimilation of hydrocarbons by the diatoms has also been proved by using gas chromatography. The competition between two species in the presence and absence of oil has been studied to obtain an idea of the ecological importance of this form of pollution.

Reproductive biology of the starfishPharia pyramidatus(Echinodermata: Asteroidea) from the Mexican tropical Pacific

2012 ◽  
Vol 92 (6) ◽  
pp. 1409-1418 ◽  
Author(s):  
Francisco Benítez-Villalobos ◽  
Maritza Martínez-García
Keyword(s):  
Reproductive Biology ◽  
Gonad Index ◽  
Pyloric Caecum ◽  
Tropical Pacific ◽  
Tropical Species ◽  
Generalist Predator ◽  
Reproductive Pattern ◽  
Sea Bottom ◽  
Males And Females ◽  
Ecological Importance

The starfishPharia pyramidatusis a tropical species of high ecological importance, mainly because of its role as generalist predator. Nevertheless, there are no studies about its reproduction. This study analysed the reproductive biology ofP. pyramidatusbased on monthly time-series samples from April 2008 to March 2009 at Isla Montosa in the Mexican tropical Pacific. The gonad index (GI), and pyloric caecum index (PCI) were determined and the results were corroborated by histological examination of the gonads.Pharia pyramidatusis a gonochoric asteroid and the ratio of males to females was not significantly different throughout the year. Gametogenesis showed high synchrony among males and females and five stages were recognized for both sexes. Spawning occurred from July to September. Maximum oocyte size was ~150μm and mean fecundity was 7.3 ± 1.2 millions of oocytes per female. GI and PCI showed seasonal variations and an inverse relationship from May to August. Sea-bottom temperature and photoperiod showed a direct relationship with GI, and apparently constitute the proximate causes of the seasonal reproductive pattern observed inP. pyramidatus, while the highly seasonal rainfall and strong upwelling probably act as ultimate causes.

scholarly journals Biotic effects of the Ordovician Kinnekulle ash-fall recorded in northern Estonia

2003 ◽  
Vol 50 ◽  
pp. 115-123
Author(s):  
Olle Hints ◽  
Linda Hints ◽  
Kadri Sohar
Keyword(s):  
Species Diversity ◽  
Volcanic Ash ◽  
Late Ordovician ◽  
Individual Species ◽  
Benthic Organisms ◽  
Direct Effects ◽  
Ash Fall ◽  
Ash Layer ◽  
Biotic Effects

The Late Ordovician (455 Ma) Kinnekulle volcanic ash-fall represents one of the largest ash eruptions known in Phanerozoic history. The dynamics of ostracodes, polychaete annelids and some shelly macrofauna across the Kinnekulle Bed in the Pääsküla section, northern Estonia indicate some significant faunal changes. The ostracod assemblage underwent major reorganization, including the replacement of predominant forms, a drop in taxon frequency and species diversity, and the probable extinction of some species following the ash-fall. The abrupt response of ostracodes indicates that the sediment surge and the resulting seafloor environment significantly affected the ostracodes. Jaw-bearing polychaetes (as represented by scolecodonts) display changes in their diversity curve and in the abundance of individual species above the altered ash layer. This change occurred after some delay indicating that polychaetes were not affected directly by the sediment influx but indirectly, probably by a change in their relationships with other biotas during a gradual rearrangement of seabed communities triggered by the ash-fall. Macrofaunal data also contains some evidence of the possible direct effects of the ash-fall. Thus, the biotic effects of the Kinnekulle ash-fall were probably larger than previously suggested. Many benthic organisms were strongly affected and the influence of this event persisted some time after the ash-fall.

scholarly journals Heavy metals in benthic organisms from Todos os Santos Bay, Brazil

2008 ◽  
Vol 68 (1) ◽  
pp. 95-100 ◽  
Author(s):  
GM. Amado-Filho ◽  
LT. Salgado ◽  
MF. Rebelo ◽  
CE. Rezende ◽  
CS. Karez ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Scientific Information ◽  
Local Population ◽  
Marine Ecosystems ◽  
Food Sources ◽  
Marine Biota ◽  
Benthic Organisms ◽  
Metal Levels ◽  
Padina Gymnospora ◽  
Ecological Importance

The marine ecosystems of Todos os Santos Bay (TSB, The State of Bahia, Brazil) have been impacted by the presence on its coast of a large metropolitan area as well as of chemical and petrochemical activities. Despite its ecological importance, there is a lack of scientific information concerning metal contamination in TSB marine biota. Thus, we analyzed concentrations of metals in four species of marine benthic organisms (two seaweeds, Padina gymnospora and Sargassum sp. one seagrass, Halodule wrightii and one oyster, Crassostrea rhizophorae) in three sites from the TSB region that have been most affected by industrial activities. The concentrations of Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn were determined by Atomic Absorption Spectrophometry. The obtained data indicates that cadmium and copper in seaweeds, oysters and seagrass, as well as Ni concentrations in oysters, were in range of contaminated coastal areas. Cadmium and copper are available to organisms through suspended particles, dissolved fraction of water column and bottom sediment interstitial water. As oysters and other mollusks are used as food sources by the local population, the metal levels found in oysters in TSB may constitute a health risk for this population. Our results suggest implanting a heavy metals biomonitoring program in the TSB marine ecosystems.

scholarly journals Ecological importance of survival of unwanted invertebrates discarded in different NW Mediterranean trawl fisheries

2018 ◽  
Vol 82 (S1) ◽  
pp. 189 ◽  
Author(s):  
Montserrat Demestre ◽  
Paolo Sartor ◽  
Alfredo Garcia-de-Vinuesa ◽  
Mario Sbrana ◽  
Francesc Maynou ◽  
...  
Keyword(s):  
Marine Ecosystem ◽  
Mortality Estimation ◽  
Fisheries Resources ◽  
Eu Directive ◽  
Management Measures ◽  
Fisheries Policy ◽  
Nw Mediterranean ◽  
Ecological Importance ◽  
Benthic Ecosystems ◽  
Trawl Fisheries

There is currently very little information on the survival of discards of unwanted and unregulated catches of invertebrates after the stresses caused by capture. A great number of the unregulated invertebrate species form the basis of essential fish habitats for important fisheries resources such as hake, red mullet and cuttlefish. Thus, data on their survival after discarding may help to interpret the role of these species within the benthic ecosystems. Furthermore, descriptor 6 of the Marine Strategy Framework Directive (EU Directive 2008/56/E) foresees maintaining sea floor integrity at a level that ensures that the structure and functions of the ecosystems are safeguarded, and Article 7(d) of the Common Fisheries Policy (EU Reg. 1380/2013) foresees the implementation of management measures for fishing with low impact on the marine ecosystem and fishery resources. Survival measurements by direct recovery of tagged discarded species are not effective in bottom trawl fisheries, for which alternative studies such as semi-quantitative measures obtained on board prior to discarding can be considered as appropriate for mortality estimation. The present work assessed the survival of unwanted species using a semi-quantitative assessment on the deck of trawlers and at the laboratory for a period of 96 hours in two Mediterranean areas (the Catalan coast and the Ligurian and Northern Tyrrhenian seas). A high number of discarded invertebrates showed a high percentage of survival (>70%) in both assessments. The results can be used to provide information that can help to achieve higher survival levels of discarded specimens and enhance the productivity of fishing grounds by increasing the health of benthic ecosystems.

scholarly journals GEOMORPHIC AND SEDIMENTARY IMPACTS ON THE CONTINENTAL SHELFAFTER ACCUMULATED DREDGE DISPOSAL FROM RIO DE JANEIRO HARBOR, BRAZIL

2019 ◽  
Vol 37 (4) ◽  
pp. 515
Author(s):  
Gilberto Tavares de Macedo Dias ◽  
Luiz Henrique P. Fontana ◽  
Cleverson Guizan Silva ◽  
Rafael Cuellar de Oliveira e Silva ◽  
Uirá Cavalcanti Oliveira ◽  
...  
Keyword(s):  
Grain Size ◽  
Continental Shelf ◽  
Rio De Janeiro ◽  
Sediment Accumulation ◽  
Dredged Material ◽  
Side Scan Sonar ◽  
Sea Bottom ◽  
Negative Impacts ◽  
Benthic Ecosystems ◽  
Seabed Sediments

ABSTRACT.Marine dredging is a subaquatic excavation activity executed around the globe for various purposes by many industries. The negative impacts ofdredged material discharge on benthic ecosystems are diverse. Researches on the results of dredging on estuarine geomorphology and its sedimentary regime areusual. Still, the results of dumping dredged material off the coast, in the Brazilian continental shelf, are not easily found in the literature. The present research evaluatedthe geomorphic disturbance resulted from discharging dredged material from Rio de Janeiro Harbor in the inner Rio de Janeiro continental shelf. Grain size analysisof the dredged and dumped sediments was compared to the inner shelf original seabed sediments. The geomorphological impact was evaluated through bathymetricand high resolution seismic and side scan sonar imagery methods. Obtained data revealed significant geomorphologic changes on the offshore bottom caused by theaccumulation of compacted mud from the dredge site underlying the recent soft mud bottom of the harbor area. Besides the morphological sea bottom disturbance,sediment accumulation, and local grain size characteristics exhibited significant change, potentially impacting the surrounding benthic environment.Keywords: Guanabara Bay, seafloor geomorphology, marine sediments, marine pollution.RESUMO.A dragagem marinha é uma atividade de escavação subaquática executada em todo o mundo por muitas indústrias para diferentes fins. Os impactosnegativos do descarte de material dragado nos ecossistemas bentônicos são diversos. Pesquisas sobre os resultados da dragagem na geomorfologia estuarina e o seuregime sedimentar são frequentes. Ainda assim, os resultados do despejo de material dragado ao longo da costa, na plataforma continental brasileira, não são facilmenteencontrados na literatura. A presente pesquisa avaliou o distúrbio geomórfico resultante do descarte de material dragado do Porto do Rio de Janeiro na plataformacontinental interna do Rio de Janeiro. A granulometria dos sedimentos dragados e descartados foi comparada com os sedimentos originais do fundo marinho naplataforma interna. O impacto geomorfológico foi avaliado através de métodos batimétricos, sísmica de alta resolução e imageamento por sonar de varredura lateral.Os dados obtidos revelaram mudanças geomorfológicas significativas no fundo causadas pelo acúmulo de lama compactada do local dragado, subjacente ao fundode lama mole recente da área do porto. Além do distúrbio morfológico do fundo marinho, o acúmulo de sedimentos e as características locais de tamanho de grãoapresentaram mudança significativa, potencialmente impactando o ambiente bentônico circundante.Palavras-chave: Baía de Guanabara, geomorfologia submarina, sedimentos marinhos, poluição marinha.

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