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The Strait to come

In 2015 an Asian brown alga, Rugulopteryx okamurae, appeared in Ceuta. Within a few years it covered the rocky bottoms of both shores, displaced entire communities and filled the beaches with thousands of tonnes of wrack. It is the largest ecological change the Strait has seen in a decade, and the open data barely records it.

Asian brown alga · Photograph: Donald Davesne, CC BY, via iNaturalist

This page shows both things at once: which species have arrived, and how many openly licensed observations each has in the area. The distance between the two columns is the size of the gap Bioestrecho has to fill with agreements, with REDIAM and with its own observation.

When they arrived

Each species placed on the year of its first record in the area. A dot is a known year; a band, an approximate decade; an arrow, an arrival before the series.

200020052010201520202025TODAYHarpoon weedbefore 2000 · 15Tropical Asparagopsis2000–2009 · 3Sally Lightfoot crab2000–2009 · 0Caulerpa2000–2009 · 0Asian brown alga2015 · 9Feather duster worm2019 · 3Blue crab2021 · 30
year of first recordapproximate decadebefore 2000The figure next to the name is the total of open records.

Non-native species of the area and open observations per year

  • Photo: Donald Davesne, CC BY

    Alga

    Asian brown alga

    Rugulopteryx okamurae

    The greatest recent transformation of the Strait's rocky seabed. The first alga in the Spanish Catalogue of Invasive Alien Species.

    First record
    2015 (Ceuta)
    Open observations
    9
    Per year, 2010–2026
  • Photo: Neto AIA, Prestes ACL, Azevedo JMN, Resendes R, Álvaro NV, Neto RMA, Moreu I (2020) Marine algal flora of Formigas Islets, Azores. Biodiversity Data Journal 8: e57510. https://doi.org/10.3897/BDJ.8.e57510, CC BY 4.0

    Alga

    Harpoon weed

    Asparagopsis armata

    Established on both shores; forms seasonal mats in spring.

    First record
    20th century
    Open observations
    15
    Per year, 2010–2026
  • Photo: Andre Hosper, CC BY

    Alga

    Tropical Asparagopsis

    Asparagopsis taxiformis

    A warm-water species; its spread accompanies the tropicalisation of the Mediterranean.

    First record
    2000s
    Open observations
    3
    Per year, 2010–2026
  • Photo: Reuven Martin, CC0

    Crustacean

    Blue crab

    Callinectes sapidus

    Arrived from the eastern Mediterranean; already in the Palmones estuary.

    First record
    2021 (bay)
    Open observations
    30
    Per year, 2010–2026
  • Photo: Silke Baron, CC BY

    Crustacean

    Sally Lightfoot crab

    Percnon gibbesi

    Frequent on breakwaters, although the open data for the area does not record it.

    First record
    2000s
    Open observations
    0
    No open records in the area across the whole series.
  • Photo: Paulo Nogueira, CC BY

    Annelid

    Feather duster worm

    Branchiomma luctuosum

    A coloniser of harbours and moorings; typical of port waters.

    First record
    2019
    Open observations
    3
    Per year, 2010–2026
  • Photo: Julien Renoult, CC BY

    Alga

    Caulerpa

    Caulerpa cylindracea

    Widespread in the Mediterranean; no open observations in the area, which says more about the data than about the alga.

    First record
    2000s
    Open observations
    0
    No open records in the area across the whole series.

CC0 and CC BY records in the extended area, GBIF. Few records for a species does not mean it is rare: it means nobody has uploaded it to an open database. First-occurrence dates come from the literature and from the Spanish Catalogue of Invasive Alien Species.