Tomás Gallardo’s research while affiliated with Complutense University of Madrid and other places

Canopy-forming seaweeds sustain critical ecosystem services in coastal habitats. Around the world, many of these seaweeds are suffering strong declines, mainly attributed to the progressive increase in sea surface temperature, in combination with other stressors due to current global changes. The southernmost part of the NE Atlantic is among those areas most affected by climate change. In this study, we estimated the distributional contractions of seven of the most conspicuous seaweeds from the Atlantic coasts of the Iberian Peninsula using an "Extent of Occurrence" methodology. Overall, during the last three decades , range shifts have been more pronounced east of the Cantabrian Sea than along the western coast of the Iberian Peninsula. In particular, regions with a semi-permanent summer upwelling seem to be critical to the persistence of brown seaweeds, fucoids and kelps. Range contractions of the cold-temperate fucoids were estimated to be ca. 21% and 45% for Himanthalia elongata and Fucus serratus, respectively; and for the kelps Saccharina latis-sima and Laminaria hyperborea, 6% and 14%, respectively. Range contractions for warm-temperate kelps were estimated to be ca. 13% and 10% for Saccorhiza polyschides and L. ochroleuca, respectively. Finally, a decline in the warm-temperate red algae Gelidium corneum occurred only in the easternmost area of the Cantabrian Sea (Basque Country), leading to a distributional contraction of 7%. We recommend conservation actions to better manage the remnant populations of these canopy-forming seaweeds, and their inclusion in national and regional catalogues of endangered species and on international Red Lists.

En 2012 responsables del Ministerio de Agricultura, Alimentación y Medioambiente de España (MAGRAMA) a través de su División para la Protección del Mar, se pusieron en contacto con la Sociedad Española de Ficología (SEF), solicitando su colaboración en la elaboración de la denominada Lista Patrón de las Especies Marinas Presentes en España, elemento básico de la Ley 41/2010 de Protección del Medio Marino. El compromiso de la SEF y de algunos de su miembros, fue el de participar de manera desinteresada en la elaboración de la parte de la Lista correspondiente a las algas bentónicas y fanerógamas marinas españolas. La Lista se ha estructurado siguiendo los criterios sistemáticos y taxonómicos de la base de datos AlgaeBase (Guiry & Guiry 2016), ampliamente aceptados en la actualidad. Se han catalogado las especies y taxones subespecíficos (subespecies, variedades y formas) citados para el litoral ibérico, baleárico, norteafricano y canario, indicando su presencia en cada una de las Demarcaciones Marinas.

Geographical range shifts of two canopy-forming seaweeds, Himanthalia elongata (L.) S.F. Gray and Fucus serratus L. were investigated at their southern range boundary in Northern Spain from the end of nineteenth century to 2009. Given the good dispersal abilities of H. elongata and its short life-span, we hypothesize that this species will track environmental changes at a faster rate than the perennial and short-distance disperser F. serratus. Our results show a continuous and drastic westward retraction of H. elongata, which has nowadays virtually vanished in Northern Spain, whereas F. serratus is still found in the westernmost area. Despite this, the first species is still relatively abundant in the Iberian Peninsula, whereas the presence of the latter is scattered and reduced. Overall, range shifts fit with the warming trend in sea surface temperature (SST), whereas it is unlikely that increases in grazing pressure or coastal pollution have driven the observed changes, particularly the rapid trend in recent years. Differences in species traits are linked to range dynamics. The higher persistence of F. serratus at eastern shores may thus be related to its longer life span and its greater thermal tolerance. The presence of sporadic populations of H. elongata outside the zone of continuous distribution can be attributed to long-distance dispersal events during cold pulses. Relict populations in isolated and estuarine locations were left behind in the contracting range margins, particularly for F. serratus. In Northern Spain, the westward retreat of large canopy-forming algae seems to be a general phenomenon, involving other species such as kelps. Therefore, an evident reorganization of coastal assemblages is expected, though the temporal extent of changes and the consequences for ecosystem services need to be evaluated.

Pseudopolyides furcellarioides gen. et sp. nov. (Gigartinales, Rhodophyta) was described from the Atlantic coasts of the northern Iberian Peninsula based on morphological and molecular evidence. This plant was found growing in the lower intertidal to the upper subtidal of moderately exposed rocky coasts, the bases anchored to rocks and often covered by sand. Thalli were perennial, terete, dichotomously branched and erect from a mammillate crustose holdfast. Fronds were multiaxial with a compact filamentous medulla, a densely pseudoparenchymatous inner cortex and an anticlinal outer cortex. Gametophytes were dioecious and isomorphic to tetrasporophytes. Spermatangia were superficial on swollen branch tips. Gonimocarps were spindle-shaped and directed to the thallus interior, while tetrasporangia were zonate. The habit and internal structure resembled those of both Polyides rotundus (characterized by crustose holdfasts, dichotomous or trichotomous branching and similar longitudinal section) and Furcellaria lumbricalis (distinguished by internal gonimocarps and zonate tetrasporangia). All three species occasionally occurred sympatrically in the Iberian Peninsula and were easily misclassified. Molecular phylogenetic analyses placed Pseudopolyides furcellarioides within the previously monogeneric Cruoriaceae, making it the first non-crustose representative of this family.