José M. Rico

SEASONAL VARIATION OF P CONTENT AND MAJOR N POOLS IN PALMARIA PALMATA (RHODOPHYTA)1

The annual variation of major nitrogen pools, phosphorus, carbon, ash, and thallus water content in relation to seasonal environmental changes was studied in two northern Spanish populations of the edible seaweed Palmaria palmata (Linnaeus) Kuntze. Observed patterns were investigated using Spearman rank order correlation coefficients. There were significant relationships between thallus nutrient content and nitrate and orthophosphate seawater concentration, irradiance, temperature, and wave force. The highest levels of total N and P and nitrogenous compounds were observed during autumn and winter because the thallus stored N‐ and P‐rich compounds in response to high nutrient seawater concentration when growth was limited by low light and temperature. Phycoerythrin and other proteins were the main N reserves. Thallus P content was higher in algae from the eutrophic site. During spring, reduced N and P thallus content and increased ash, water, and C content were observed in the growing fronds. N and P seawater concentrations were undetectable during summer when nutrient reserves were low and growth was reduced and eventually suppressed, suggesting nutrient limiting conditions. Palmaria palmata clearly could take advantage of elevated N and P concentrations to create storage reserves in winter to support early summer growth. This storage response reduced the dependence of algal nutrition on the external nutrient supply and supports the use of pulse fertilization to diminish summer nutrient limitation of cultured algae.

Climate driven changes in subtidal kelp forest communities in NW Spain

Reconstructions suggest a massive decline of nearly 1400 ha of kelp forest in North Western Spain in 2007. In line with global rising temperatures, we hypothesized that Sea Surface Temperature (SST) surpassed a lethal threshold for kelp. We examined whether changes in SST correlated to the proposed decline in kelp forest. All investigated SST characteristics suggested to affect kelp abundance increased significantly during the past thirty years, reaching extreme values during the last decade. In addition over the past two decades, the landscape formerly dominated by both cold and warm temperate canopy forming and understory species changed to one dominated by warm temperate understory species, resulting in a loss of vertical community structure. Fisheries landing data of kelp associated species was used to support the suggested change in kelp abundance. Subsequent recovery of the kelp appears to be occurring in deeper waters.

Seasonal nitrogen metabolism in an intertidal population of Gelidium latifolium (Gelidiaceae, Rhodophyta)

The nitrogen status of Gelidium latifolium on the north coast of Spain was monitored for a 2 year period from 1990 to 1991. Each summer, the population showed obvious symptoms of nitrogen (N) limitation, such as thallus ‘bleaching’. Minimum N content (as % of dry weight), highest C/N ratio (above 45) and lowest protein (< 10% dry weight) and phycobilin contents were observed during summer, when nitrate availability in seawater was lowest, and temperature and light levels were highest. However, tissue N content did not respond to a short local upwelling period that increased nitrate levels in seawater more than ten-fold. The effect of seawater N concentration and increased light levels on pigment content was established experimentally. N-starved plants placed in N-enriched seawater during summer 1990 showed increased levels of phycobilin and chlorophyll a compared with an unenriched control. Screens which transmitted different proportions of natural light placed over a Gelidium latifolium population during...

INORGANIC NITROGEN AND PHOSPHORUS UPTAKE KINETICS IN PALMARIA PALMATA (RHODOPHYTA) 1

The N and P uptake responses were studied in a northern Spanish population of the edible red seaweed Palmaria palmata (Linnaeus) Kuntze. The fronds were incubated at different concentrations, and the nutrient depletion in the medium was measured at successive times to calculate uptake rates. Palmaria palmata uptake response was biphasic and nonsaturable for inorganic P. This would allow the species to exploit transient pulses of high P concentration in natural and fertilized conditions. Such a response is a common feature of algae avoiding nutrient deficiency. At average concentrations measured in the ocean, the response was nonsaturable for inorganic N sources, except for ammonium in autumn and winter when it is not the major N source. In contrast to the general rule of ammonium being taken at a higher rate than nitrate, we found similar affinity for both nutrients corresponding to the minor role of ammonium as N source for field populations over the year.

Field studies and growth experiments on Gelidium latifolium from Asturias (northern Spain)

Seasonal cycles of environmental factors (temperature, day-length, nutrient concentration) and changes in Gelidium latifolium biomass, percentage reproduction and size are given, and non-parametric correlation is used to quantify possible relationships. The results are compared with growth experiments, testing effects of total light dosage, agitation, temperature and Photon Flux Density (PFD). Results of total light dosage × agitation growth experiment show that maximum growth is obtained when plants are cultured at a long photoperiod (16 : 8 L/D) with agitation. Results of temperature × PFD experiment show that maximum growth is obtained at PFD values higher than 50 µE m−2 s−1 at temperatures between 20–25 °C. Possible applications of field studies and culture experiments in management of wild resources and industrial cultivation are proposed.

Morphology and systematics of Gelidiella tenuissima (Gelidiales, Rhodophyta) from Gran Canaria (Canary Islands, Spain)

Abstract Fertile male gametophytes of Gelidiella tenuissima are described for the first time, from cultured plants collected in Gran Canaria (Canary Islands, Spain). The morphology of male reproductive structures in this species is similar to other gametophytes referred to the Gelidiales, but different from the recently described male gametophyte of the type species of Gelidiella, G. acerosa. Morphological comparisons between these two species, using the male gametophyte and the tetrasporangial stichidia, and also molecular analyses, suggest that two different groups of species are included in the genus Gelidiella.

CHANGES IN NUTRIENT CONTENT OF PALMARIA PALMATA IN RESPONSE TO VARIABLE LIGHT AND UPWELLING IN NORTHERN SPAIN1

Light has been identified as one of the main factors affecting seaweed ecophysiology. We investigated the dependence of nutrient metabolism on sun and shade light conditions and whether episodes of upwelling of nutrient‐rich subsuperficial water could reduce the summer nutrient limitation driving physiological changes in Palmaria palmata (L.) Kuntze. We measured the major nutrient pools, photosynthetic pigments, and light curves, under sun and shade conditions during a summer period when one upwelling was recorded. The redundancy analysis (RDA) produced two clear groups: sun‐ and shade‐acclimated algae. Light was the major predictive factor. Sun‐acclimated algae exhibited higher carbon (C) and lower nitrogen (N) and phosphorus (P) content in association with the storage of floridoside (main C reserve) to benefit from higher irradiance (under nutrient limitation). Among N pools, N reserves (phycoerythrin, nitrate) were a lower proportion of the total N in sun‐acclimated algae, suggesting their degradation to fulfill the N demands of the cell. The orthophosphate content was also lower in sun‐acclimated algae, indicating its utilization as a nutrient reserve. In contrast, N within cell walls and membranes and chl a contributed to a similar proportion of the total N in sun‐ and shade‐acclimated algae, suggesting a response to sustain cell integrity. Transient high nutrient concentration due to the upwelling was unrelated to the nutrient content of the thallus. The storage of C as floridoside from high light exposure was shown to be the driving force for the metabolic adjustment of P. palmata at the end of summer before the onset of dormancy.

A comparison of the degree of implementation of marine biodiversity indicators by European countries in relation to the Marine Strategy Framework Directive (MSFD)

The degree of development and operability of the indicators for the Marine Strategy Framework Directive (MSFD) using Descriptor 1 (D1) Biological Diversity was assessed. To this end, an overview of the relevance and degree of operability of the underlying parameters across 20 European countries was compiled by analysing national directives, legislation, regulations, and publicly available reports. Marked differences were found between countries in the degree of ecological relevance as well as in the degree of implementation and operability of the parameters chosen to indicate biological diversity. The best scoring EU countries were France, Germany, Greece and Spain, while the worst scoring countries were Italy and Slovenia. No country achieved maximum scores for the implementation of MSFD D1. The non-EU countries Norway and Turkey score as highly as the top-scoring EU countries. On the positive side, the chosen parameters for D1 indicators were generally identified as being an ecologically relevant reflection of Biological Diversity. On the negative side however, less than half of the chosen parameters are currently operational. It appears that at a pan-European level, no consistent and harmonized approach currently exists for the description and assessment of marine biological diversity. The implementation of the MSFD Descriptor 1 for Europe as a whole can therefore at best be marked as moderately successful.

Occurrence and speciation of arsenic and mercury in estuarine sediments affected by mining activities (Asturias, northern Spain)

Sediments contaminated by Hg and As from two historical mining areas have been deposited in the Nalón estuary (Asturias, northern Spain) since 1850. Total mercury (Hgtotal) concentrations in the sediments range from 0.20 μg g-1 to 1.33 μg g-1, most of it in the form of sulphides. Concentrations of methylmercury (303.20-865.40 pg g-1) are up to two orders of magnitude lower than the concentration of Hgtotal. Total As concentration (Astotal) is enriched compared to the background level for the area. The relative abundance of As(V) on As(III) in the sediments ranges from 97.6% to 100%, whereas inorganic Hg accounts for more than 99% of the total Hg. The occurrence of the most toxic species, inorganic As(III) and organic methylmercury, seem to be related to redox conditions together with the amounts of sulphur which act as natural barriers which inhibit the biological and chemical speciation processes. Despite the high amounts of Hg and As present in the sediments, their transference to the water column appear to be limited thus converting sediments in an effective sink of both elements. Special attention should be paid to potential variations of the environmental conditions which might increase the element mobility and exchange between sediments and the water column.

Morphological and molecular methods reveal the Asian alga Grateloupia imbricata (Halymeniaceae) occurs on Cantabrian Sea shores (Bay of Biscay)

Abstract: Introduction of nonindigenous species (NIS) via anthropogenic activities (i.e. shipping) has serious consequences for marine ecosystems. On shores of the Cantabrian Sea (northern Spain), there is no routine NIS screening combining molecular and anatomical methods. This makes the detection of inadvertent expansions of exotic species difficult. In this work, a screening of nonfoliose Grateloupia specimens combining morphological and DNA barcoding procedures (COI-5P and rbcL genes) was conducted in the marina of Gijón, Bay of Biscay. A reproductive population of G. imbricata was found. This is the first report of this introduced Asian seaweed in continental Atlantic Europe. The detection of this species on shores of the Spanish Atlantic is relevant biogeographically since other previous records in the North Atlantic suggest a stepping-stones route via the Azores and Canary Islands. Routine screenings for early detection of exotic algae is becoming a powerful risk assessment tool for further introductions.