• Climate crisis drives Mediterranean cora

    From ScienceDaily@1:317/3 to All on Wed Jan 19 21:30:36 2022
    Climate crisis drives Mediterranean coral populations to collapse
    Mass mortality events

    Date:
    January 19, 2022
    Source:
    University of Barcelona
    Summary:
    A new study has revealed that marine heatwaves associated with
    the climate crisis are bringing down the populations of coral in
    the Mediterranean, the biomass of which in some cases has been
    reduced by 80 to 90%.



    FULL STORY ==========================================================================
    A new study led by teams of the Faculty of Biology, the Biodiversity
    Research Institute (IRBio) of the University of Barcelona, and the
    Institute of Marine Sciences (ICM-CSIC) of Barcelona has revealed that
    marine heatwaves associated with the climate crisis are bringing down
    the populations of coral in the Mediterranean, the biomass of which in
    some cases has been reduced by 80 to 90%.


    ========================================================================== According to the study, published in the journal Proceedings of the
    Royal Society B, coral populations of the Mediterranean -- essential for
    the functioning of the coral reefs, one of the most emblematic habitats
    in this sea -- could be unable to recover from the recurrent impact of
    these extreme episodes, with water temperatures reaching high degrees
    for days and even weeks.

    This is the first study to assess the long-term recovery capacity of populations of two emblematic species of Mediterranean coral: the red
    gorgonian (Paramuricea clavata) and the red coral (Corallium rubrum),
    which provide complex habitats that are essential for a great diversity
    of associated fauna.

    Therefore, it is essential to understand their resilience regarding the
    more frequent and intense heatwaves.

    Mass mortality events The climate crisis is severely affecting the
    marine ecosystems worldwide, and the Mediterranean is no exception. In particular, the marine heatwaves associated to the climate crisis are
    causing mass mortality events in all the coastal ecosystems of this basin,
    and among the most affected species are the Mediterranean corals.

    Knowledge on the coral's long-term resilience is still scarce, despite
    the studies that analysed the immediate impact of marine heatwaves on
    these organisms. These are long-lived species (more than a hundred years
    in some cases) and with slow populational dynamics (that is, organisms
    with low growth and recruitment rates), and therefore researchers need
    long temporary series (decades) to assess their recovery capacity.



    ==========================================================================
    As part of the study, the team analysed the results obtained in a
    long-term monitoring on different populations of coral affected by a
    great mass mortality caused by a heatwave in 2003 in the protected marine
    area of Scandola (Corsega, France). In particular, they analysed data
    on the state of these populations (density, size structure and biomass) collected during the following fifteen years to the heatwave, by the researchers of the MedRecover research group, formed by experts of the
    UB and ICM-CSIC, among other centres.

    Far from recovery, the results show that all the analysed populations
    tended to collapse since they were affected by the 2003 heatwave. Fifteen
    years after this event, these populations are practically considered to
    be extinct from a functional perspective.

    "We observed an average biomass loss regarding the initial biomass of 80%
    in populations of red gorgonian, and up to a 93% regarding the studied population of red coral," notes Daniel Go'mez, researcher at ICM-CSIC.

    "These data are worrying for the conservation of these emblematic species,
    and it indicates that the effects of the climate crisis are speeding up
    with obvious consequences for the submarine landscapes, where the loss
    of coral equals the loss of trees in forests," notes Joaquim Garrabou,
    also member of ICM-CSIC.

    Recurrent exposure to heatwaves Cristina Linares, professor at the
    Department of Evolutionary Biology, Ecology and Environmental Sciences
    of the Faculty of Biology and member of IRBio, says that "we believe one
    of the main reasons why we observed these collapse trajectories is the potential recurrent exposure to heatwaves, incompatible with the slow populational dynamics of these species." In particular, during the study
    period (2003-2018), they registered important heatwaves in at least four
    years: 2009, 2016, 2017, 2018.



    ========================================================================== "During these heatwaves," continues Linares, "the temperature conditions
    in the studied area reached extreme levels which are incompatible with
    the life of these corals, which probably caused new mortality events to
    the decimated populations and made the recovery impossible." Since we
    expect the number and intensity of marine heatwaves to increase over
    the following decades due to the climate crisis, the viability of many
    coral populations could be seriously threatened.

    "However, there will probably be some areas in the Mediterranean in
    which, due to several factors, the recurrence of such climate impacts
    may be lower. This makes it especially relevant to keep -- regarding
    other potential impacts - - these climate refuges where the trajectories
    of coral populations could be more positive than those observed in this
    study," notes the research team.

    "Nevertheless, there is an urgent need for stronger measures to be
    implemented against the climate crisis before the loss of biodiversity
    becomes irreplaceable," conclude the experts.

    This study has been carried out thanks to the support of the
    Regional Natural Park of Corsica, the HEATMED National Plan project (RTI2018-095346-B-485 I00), the European projects H2020, MERCES, H2020 Futurmares, Interreg MED MPA-Engage and Interreg MED MPA-Adapt.

    ========================================================================== Story Source: Materials provided by University_of_Barcelona. Note:
    Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. D. Go'mez-Gras, C. Linares, A. Lo'pez-Sanz, R. Amate, J. B. Ledoux,
    N.

    Bensoussan, P. Drap, O. Bianchimani, C. Marschal, O. Torrents, F.

    Zuberer, E. Cebrian, N. Teixido', M. Zabala, S. Kipson,
    D. K. Kersting, I. Montero-Serra, M. Page`s-Escola`, A. Medrano,
    M. Frleta-Valić, D.

    Dimarchopoulou, P. Lo'pez-Sendino, J. Garrabou. Population
    collapse of habitat-forming species in the Mediterranean: a
    long-term study of gorgonian populations affected by recurrent
    marine heatwaves. Proceedings of the Royal Society B: Biological
    Sciences, 2021; 288 (1965) DOI: 10.1098/rspb.2021.2384 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/01/220119121355.htm

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