Notas corológicas del macrofitobentos de Andalucía (España). IX

La flora de macroalgas marinas de Andalucía se recoge en los catálogos de Flores-Moya et al. (1995a, 1995b) y Conde et al. (1996a), y en las adiciones posteriores de Conde et al. (1996b), Báez et al. (2001), Altamirano et al. (2006, 2008) e Invernón et al. (2009). En este trabajo, se aportan tres nuevas citas para Andalucía (señaladas con un asterisco), seis citas nuevas para la provincia de Cádiz y una confi rmación para esta provincia. El material recolectado fue identifi cado, y depositado (bien en formol al 4% o bien en pliegos) en el herbario MGC Phyc. Se ha utilizado ALGAEBASE (Guiry & Guiry, 2010) como referencia a la hora de nombrar los diferentes taxones

Interaction between hydrodynamics and seagrass canopy structure: Spatially explicit effects on ammonium uptake rates

The hypotheses that (1) different seagrass morphologies may facilitate different nutrient uptake rates under similar hydrodynamic forcing and (2) this effect on nutrient uptake rates is spatially explicit, with the highest uptake rates at edges of patches, where currents and turbulence are highest, were examined under unidirectional flow conditions.We thank Jos van Soelen, Bas Koutstaal, and Louie Haazen for invaluable technical assistance. In addition, we are grateful to Britta Gribsholt, Bart Veuger, Miguel Bernal, Juan Jose Vergara, and Alfredo Izquirdo for helpful discussion. In addition, we thank Josef D. Ackerman and the anonymous reviewers for comments that greatly improved the manuscript. This work and the first author were supported by an EU Marie Curie host fellowship for transfer of knowledge, MTKD-CT-2004-509254, and the Spanish national project EVAMARIA, CTM2005-00395/MAR. F.G.B. holds an EU Marie Curie individual fellowship, MEIF-CT-2005-515071. This is publication 4251 of the Netherlands Institute of Ecology (NIOO-KNAW)

Recuperación Fotosintéctica de Cymodocea nodosa (Ucria) Ascherson después un periodo de cuatro meses en oscuridad

P align=justify>Cymodocea nodosa plants were dark incubated for four months. The potential of reactivating photosynthesis was tested in an experiment in which half of the plants were reilluminated (HL) while the other half were grown under very low irradiance levels (LL). Photosynthesis was measured using PAM fluorescence and tissue nutrient and carbohydrate contents were analysed. Photosynthetic efficiency (Fv/Fm) in HL plants increased from 0 to 0.58, whereas LL plants remained inactive. Photosynthetic parameters also increased, resulting in a final Ik of 97.5 µmol m-2 s-1. Leaf shedding led to a negative mean RGR in HL plants. Tissue C and N dropped considerably during dark incubation in both rhizomes and shoots. Starch content was nearly equal for rhizomes and shoots (4.3 mg /g DW) and was not affected by dark incubation. In contrast, sucrose content dropped from 40.0 mg /g DW to zero in shoots and from 240 to 40.0 mg /g DW in rhizomes in HL plants. We conclude that C. nodosa is capable of recovering photosynthetic activity after four months darkness, which is considerably longer than the 80 d recorded so far for a seagrass. Stored carbohydrates, more specifically sucrose, play an important role in both survival and reactivation.  La capacidad de recuperación de la fotosíntesis se ha investigado en la fanerógama marina Cymodocea nodosa. Para ello, se diseñó un experimento en el que la mitad de las plantas se cultivaron en condiciones de luz saturante (HL) y la otra mitad en condiciones de luz muy baja (LL), tras un precultivo de 4 meses en oscuridad. Se examinó la actividad fotosintética mediante la señal de fluorescencia del PAM y se determinó el contenido interno en nutrientes y de hidratos de carbono. La eficacia fotosintética (Fv/Fm) se incrementó desde 0 hasta 0,58 en las plantas de HL, mientras las plantas de LL permanecieron fotosintéticamente inactivas. Los parámetros fotosintéticos también se incrementaron, obteniéndose valores finales para Ik de 97,5 μmol fotones m-2 s-1. Las plantas de HL mostraron valores medios negativos de la tasa de crecimiento relativo, atribuible al desprendimiento de hojas. El contenido interno de carbono y nitrógeno disminuyó considerablemente durante el periodo de oscuridad tanto en la biomasa epigea como hipogea. El contenido interno en almidón permaneció constante en ambos tejidos (4,3 mg /g DW), no estando afectado por el periodo de oscuridad. El contenido interno de sacarosa mostró un patrón opuesto, disminuyendo desde 40 mg /g DW a valores cercanos a cero en haces, y en rizomas desde 240 a 40 mg /g DW, en plantas de HL. En conclusión, C. nodosa recuperó la actividad fotosintética tras 4 meses en oscuridad, un periodo considerablemente mayor al registrado anteriormente para otras especies de fanerógamas (80 días). Los carbohidratos de reserva, y más concretamente la sacarosa, juega un papel crucial tanto en la supervivencia como en la reactivación fotosintética.

New aspect in seagrass acclimation: leaf mechanical properties vary spatially and seasonally in the temperate species Cymodocea nodosa Ucria (Ascherson)

Seagrasses may acclimate to environmental heterogeneity through phenotypic plasticity. In contrast to leaf morphology, which has been a central point in seagrass acclimation studies, plasticity in leaf biomechanics and fibre content is poorly understood, despite being crucial in plant ecological performance, especially regarding physical forces. We hypothesised that mechanical traits (e.g. breaking force, strength, toughness, and stiffness) and fibre content of seagrass leaves vary as morphology does under differential environments. Cymodocea nodosa was seasonally monitored at three locations around Ca´diz Bay (southern Spain) with hydrodynamic regime as the most noticeable difference between them. Leaves showed plasticity in both morphology and mechanical traits, with wave-exposed individuals presenting short but extensible and tough leaves. Leaf fibre content was invariant along the year and with little spatial variability. Cross-sectional area rather than material properties or fibre content differentiates leaf mechanical resistance. Seagrass capacity to thrive under a range of mechanical forces may be dictated by their plasticity in morpho-biomechanical traits, a key element for the hydrodynamical performance and, hence, for species colonisation and distribution.info:eu-repo/semantics/publishedVersio

Notas corológicas del macrofitobentos de Andalucía (España). XII.

New records for the macrophytobenthos of Andalusia (Spain). XIIPalabras clave. Andalucía, corología, macroalgas marinas.Key words. Andalusia, geographical distribution, seaweeds

Sedimentary organic carbon and nitrogen stocks of intertidal seagrass meadows in a dynamic and impacted wetland: Effects of coastal infrastructure constructions and meadow establishment time

Seagrass meadows, through their large capacity to sequester and store organic carbon in their sediments, contribute to mitigate climatic change. However, these ecosystems have experienced large losses and degrada-tion worldwide due to anthropogenic and natural impacts and they are among the most threatened ecosystems on Earth. When a meadow is impacted, the vegetation is partial-or completely lost, and the sediment is exposed to the atmosphere or water column, resulting in the erosion and remineralisation of the carbon stored. This paper addresses the effects of the construction of coastal infrastructures on sediment properties, organic carbon, and total nitrogen stocks of intertidal seagrass meadows, as well as the size of such stocks in relation to meadow establishing time (recently and old established meadows). Three intertidal seagrass meadows impacted by coastal constructions (with 0% seagrass cover at present) and three adjacent non-impacted old-established meadows (with 100% seagrass cover at present) were studied along with an area of bare sediment and two recent-established seagrass meadows. We observed that the non-impacted areas presented 3-fold higher per-centage of mud and 1.5 times higher sedimentary organic carbon stock than impacted areas. Although the impacted area was relatively small (0.05-0.07 ha), coastal infrastructures caused a significant reduction of the sedimentary carbon stock, between 1.1 and 2.2 Mg OC, and a total loss of the carbon sequestration capacity of the impacted meadow. We also found that the organic carbon stock and total nitrogen stock of the recent -established meadow were 30% lower than those of the old-established ones, indicating that OC and TN accu-mulation within the meadows is a continuous process, which has important consequences for conservation and restoration actions. These results contribute to understanding the spatial variability of blue carbon and nitrogen stocks in coastal systems highly impacted by urban development.info:eu-repo/semantics/publishedVersio

Seagrass Patch Complexity Affects Macroinfaunal Community Structure in Intertidal Areas: An In Situ Experiment Using Seagrass Mimics

[EN] Seagrasses, as key ecosystem engineers in coastal ecosystems, contribute to enhancing diversity in comparison with nearby bare areas. It has been proved mainly for epifauna, but data on infauna are still scarce. The present study addresses how seagrass structural complexity (i.e., canopy properties) affects the diversity of infaunal organisms inhabiting those meadows. Canopy attributes were achieved using seagrass mimics, which were used to construct in situ vegetation patches with two contrasting canopy properties (i.e., shoot density and morphology) resembling the two seagrass species thriving in the inner Cadiz Bay: Zostera noltei and Cymodocea nodosa. After three months, bare nearby areas, two mimicked seagrass patches (‘Zostera’ and ‘Cymodocea’), and the surrounding natural populations of Zostera noltei were sampled in a spatially explicit way. Shifts in organism diets were also determined using15N and13C analyses in available food sources and main infaunal organisms, mixing models, and niche metrics (standard ellipse area). Seagrass-mimicked habitats increased the species richness (two-fold), organism abundance (three to four times), and functional diversity compared with bare nearby areas. The clam Scrobicularia plana (deposit/filter feeder) and the worm Hediste diversicolor (omnivore) were dominant in all of the samples (> 85%) and showed an opposite spatial distribution in the reconstructed patches: whilst S. plana accumulated in the outer-edge parts of the meadow, H. diversicolor abounded in the center. Changes in the isotopic signature of both species depending on the treatment suggest that this faunal distribution was associated with a shift in the diet of the organisms. Based on our results, we concluded that facilitation processes (e.g., reduction in predation and in bioturbation pressures) and changes in food availability (quality and quantity) mediated by seagrass canopies were the main driving forces structuring this community in an intertidal muddy area of low diversitySIThis work was supported by the Spanish Project PAVAROTTI (CTM2017-85365-R) from the Ministry of Science and Innovation and by the Junta de Andalucía Excellence Project PAMBIO (P08-RNM-03783

On the use of sediment fertilization for seagrass restoration: a mesocosm study on Zostera marina

Abstract The use of nitrogen and phosphorus sediment fertilization for seagrass restoration is explored. Special attention was given to the effects of nitrogen sediment fertilization. The sediment fertilization treatment combined different levels of nitrogen (0, 30, 500 mg N g DW −1 ) with sufficient phosphorus to avoid P-limitation (fertilizer N:P ratio < 0.25). Using indoor mesocosms, we studied the effects of sediment fertilization, and its interactions with light availability (55, 200 mol m −2 s −1 ) and sediment redox conditions (300, −100 mV), on Zostera marina L. We assessed (1) treatment effects on growth and plant biomass distribution, (2) the capacity of Z. marina roots to meet the plant nutrient demand, (3) plant tolerance to high nutrient porewater concentration, and (4) pro's and con's of use NH 4 NO 3 as the N source in sediment fertilization for seagrass restoration. Plant biomass, growth and leaf turnover rate were stimulated by light and sediment fertilization. Biomass partitioning was not affected by light availability, whereas the relative root production was decreased in fertilized sediments. Root uptake following fertilization met nutrient plant demand. After high sediment fertilization, ammonium porewater concentration was high (30 mM) regardless of redox conditions. On the other hand, nitrate availability was also high, but 80% lower in reduced sediments (0.7-4 mM) compared to non-reduced ones (20 mM). Plants of Z. marina exhibited a remarkable tolerance to high N + P sediment fertilization. However, plant inhibition (reduction in plant weight, leaf growth and leaf turnover rate) was detected when porewater N concentrations exceeded 30 mM. The effects of phosphorus and ammonium toxicity were discarded because availability was similar for both inhibited and non-inhibited plants. Peralta et al. / Aquatic Botany 75 (2003) [95][96][97][98][99][100][101][102][103][104][105][106][107][108][109][110] porewater nitrogen available as nitrate (20 mM). Experimental treatments did not inhibit the photosynthetic apparatus of Z. marina. The mechanisms of inhibition might be related with deficiencies in energy or C-skeletons, since inhibitory effects were buffered when saturating irradiance and/or nitrate levels decreased in reduced sediments. In conclusion, we consider that the combined N + P sediment fertilization, with NH 4 NO 3 as N source and high P supply, is highly beneficial for Z. marina restoration. This species has positive response to N + P sediment fertilization, high tolerance to the extensive porewater enrichment, and bacterial metabolism may reduce the porewater nitrate availability in anoxic seagrass sediments. However, for adequate sediment fertilization for restoration purposes, several precautions are suggested