Cape Creus Research Articles

Surface oceanographic fronts influencing deep-sea biological activity: Using fish stable isotopes as ecological tracers

Ecotones can be described as transition zones between neighbouring ecological systems that can be shaped by environmental gradients over a range of space and time scales. In the marine environment, the detection of ecotones is complex given the highly dynamic nature of marine systems and the paucity of empirical data over ocean-basin scales. One approach to overcome these limitations is to use stable isotopes from animal tissues since they can track spatial oceanographic variability across marine systems and, in turn, can be used as ecological tracers. Here, we analysed stable isotopes of deep-sea fishes to assess the presence of ecological discontinuities across the western Mediterranean. We were specifically interested in exploring the connection between deep-sea biological activity and particular oceanographic features (i.e., surface fronts) occurring in the pelagic domain. We collected samples for three different abundant deep-sea species in May 2004 from an experimental oceanographic trawling cruise (MEDITS): the Mictophydae jewel lanternfish Lampanyctus crocodilus and two species of the Gadidae family, the silvery pout Gadiculus argenteus and the blue whiting Micromesistius poutassou. The experimental survey occurred along the Iberian continental shelf and the upper and middle slopes, from the Strait of Gibraltar in the SW to the Cape Creus in the NE. The three deep-sea species were highly abundant throughout the study area and they showed geographic variation in their isotopic values, with decreasing values from north to south disrupted by an important change point around the Vera Gulf. Isotopic latitudinal gradients were explained by pelagic oceanographic conditions along the study area and confirm the existence of an ecotone at the Vera Gulf. This area could be considered as an oceanographic boundary where waters of Atlantic origin meet Mediterranean surface waters forming important frontal structures such as the Almeria-Oran front. In fact, our results relate geographical variation in stable isotopes of deep-sea fishes to regional changes in surface oceanography, highlighting the importance of mesoscale oceanographic features.

Seasonal and interannual variability of dissolved oxygen around the Balearic Islands from hydrographic data

Oceanographic data obtained between 2001 and 2011 by the Spanish Institute of Oceanography (IEO, Spain) have been used to characterise the spatial distribution and the temporal variability of the dissolved oxygen around the Balearic Islands (Mediterranean Sea). The study area includes most of the Western Mediterranean Sea, from the Alboran Sea to Cape Creus, at the border between France and Spain. Dissolved oxygen (DO) at the water surface is found to be in a state of equilibrium exchange with the atmosphere. In the spring and summer a subsurface oxygen supersaturation is observed due to the biological activity, above the subsurface fluorescence maximum. Minimum observed values of dissolved oxygen are related to the Levantine Intermediate Waters (LIW). An unusual minimum of dissolved oxygen concentrations was also recorded in the Alboran Sea Oxygen Minimum Zone. The Western Mediterranean Deep Waters (WMDW) and the Western Intermediate Waters (WIW) show higher values of dissolved oxygen than the Levantine Intermediate Waters due to their more recent formation. Using these dissolved oxygen concentrations it is possible to show that the Western Intermediate Waters move southwards across the Ibiza Channel and the deep water circulates around the Balearic Islands. It has also been possible to characterise the seasonal evolution of the different water masses and their dissolved oxygen content in a station in the Algerian sub-basin.

Physical characteristics and dynamics of the coastal Latex09 Eddy derived from in situ data and numerical modeling

AbstractWe investigate the dynamics of a coastal anticyclonic eddy in the western part of the Gulf of Lion (GoL) in the northwestern Mediterranean Sea during the Latex campaign in the summer 2009 (Latex09). The sampling strategy combines sea surface temperature satellite imagery, hull‐mounted acoustic Doppler current profiler data, conductivity‐temperature‐depth casts, and drifter trajectories. Our measurements reveal an anticyclonic eddy (Latex09 eddy) with a diameter of ~23 km and maximum depth of 31 m, centered at 3°34′E, 42°33′N. We use a high resolution, three‐dimensional, primitive equation numerical model to investigate its generation process and evolution. The model is able to reproduce the observed eddy, in particular its size and position. The model results suggest that the Latex09 eddy is induced by a large anticyclonic circulation in the northwestern part of the GoL, pushed and squeezed toward the coast by a meander of the Northern Current. This represents a new generation mechanism that has not been reported before. The post generation dynamics of the eddy is also captured by the model. The collision of the Latex09 eddy with Cape Creus results in a transient structure, which is depicted by the trajectories of two Lagrangian drifters during Latex09. The transient structure and its advection lead to a transfer of mass and vorticity from the GoL to the Catalan shelf, indicating the importance of mesoscale structures in modulating such exchanges in the region.

Exploiting the closest productive area: geographical segregation of foraging grounds in a critically endangered seabird

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 429:291-301 (2011) - DOI: https://doi.org/10.3354/meps09126 Exploiting the closest productive area: geographical segregation of foraging grounds in a critically endangered seabird M. Louzao1,2,*, J. Navarro3, M. G. Forero4, J. M. Igual1, M. Genovart1, K. A. Hobson5, D. Oro1 1Institut Mediterrani d’Estudis Avançats IMEDEA (CSIC-UIB), Miquel Marquès 21, 07190 Esporles, Mallorca, Spain. 2Helmholtz Centre for Environmental Research-UFZ, Permoserstraße 15, 04318 Leipzig, Germany 3Institut de Ciències del Mar (CSIC), Passeig Marítim de la Barceloneta 37–49, 08003 Barcelona, Spain 4Departamento de Biología de la Conservacíon, Estación Biológica de Doñana (CSIC), Apartado 1056, 41013 Sevilla, Spain 5Environment Canada, 11 Innovation Blvd., Saskatoon, Saskatchewan S7N 3H5, Canada *Email: maite.louzao@ufz.de ABSTRACT: While breeding, seabirds are limited to exploiting resources within a restricted area around their breeding site and should exploit the closest productive marine areas within their distribution range. We investigated this hypothesis in one of the most endangered European seabirds, the Balearic shearwater Puffinus mauretanicus (ca. 3200 breeding pairs), restricted to the Balearic Islands. Our aims were (1) to assess whether isotopic evidence (i.e. stable isotopes of δ13C and δ15N) of foraging habitat partitioning occurs among northern, central and southern populations, (2) to geographically locate population-specific potential foraging grounds along the Iberian continental shelf, and (3) to assess whether oceanographic conditions could explain observed patterns of stable isotopes (SI). SI values showed a latitudinal gradient, with birds from the northern population having lower δ15N and δ13C values than central and southern populations. Potential foraging grounds of northern, central and southern populations were centred in Cape Creus, Ebro Delta and Cape La Nao, respectively, results which were supported by habitat models. Oceanographic conditions in each potential foraging ground were different; the northern population used richer, colder and deeper waters compared to the central and southern populations. Chlorophyll a was the main oceanographic variable that explained variation in SI values. We hypothesised that SI differences among Balearic shearwater populations might be a consequence of differences in baseline isotopic values among potential foraging grounds rather than real differences in diet. Our comprehensive study also provides important information for management strategies to conserve this critically endangered shearwater. KEY WORDS: Balearic shearwater · Geographical foraging ground segregation · Habitat modelling · Mediterranean Sea · Oceanography · Puffinus mauretanicus · Stable isotopes Full text in pdf format Supplementary material PreviousCite this article as: Louzao M, Navarro J, Forero MG, Igual JM, Genovart M, Hobson KA, Oro D (2011) Exploiting the closest productive area: geographical segregation of foraging grounds in a critically endangered seabird. Mar Ecol Prog Ser 429:291-301. https://doi.org/10.3354/meps09126Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 429. Online publication date: May 16, 2011 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2011 Inter-Research.

Biological implications of recreational shore angling and harvest in a marine reserve: the case of Cape Creus

Abstract Recreational shore fishing along the coast of the marine reserve of Cap de Creus (NW Mediterranean) was studied in 2007 and 2009 based on roving creel surveys (on‐site angler surveys during which anglers' harvests are examined by the survey clerk). The study aimed to assess the biological impacts of this leisure activity on coastal fish stocks and the potential risks arising from the use of exotic baits. Recreational shore fishers employ seven different fishing techniques, of which the bottom fishing rod (a fishing rod whose hooks, together with the bait, lie on the bottom or near it by means of a heavy weight) is by far the most widely used method (nearly 90% of observations). In total, 25 fish species were identified in the catch from the bottom fishing rod. The estimated annual shore fishing catches (c.3 tons) are much lower than those obtained by recreational boat and spear fishing (c.20 tons each), and those from commercial (artisanal) fishing (c.50 tons). The weighted mean vulnerability index and trophic level values in the catch from the bottom fishing rod are 52.2 and 4.03, respectively. A minimum of 43% of the baits used by the shore anglers were live, non‐native species (mostly polychaetes). Overall, results highlight the impact of shore angling on coastal fish communities of a protected area and the increasing environmental risks arising from the use of exotic marine baits, which constitute a potential and unregulated vector of introduction of non‐native species in the Mediterranean. Copyright © 2011 John Wiley & Sons, Ltd.

Combining vessel-based surveys and tracking data to identify key marine areas for seabirds

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 391:183-197 (2009) - DOI: https://doi.org/10.3354/meps08124 Combining vessel-based surveys and tracking data to identify key marine areas for seabirds M. Louzao1,5,*, J. Bécares2, B. Rodríguez2, K .D. Hyrenbach3, A. Ruiz4, J. M. Arcos2 1Centre d’Etudes Biologiques de Chizé, CNRS, 79360 Villiers en Bois, France 2Sociedad Española de Ornitología/BirdLife, C/Múrcia 2-8, local 13, 08026 Barcelona, Spain 3Duke University Marine Laboratory, 135 Duke Marine Laboratory Road, Beaufort, North Carolina 28516, USA 4Sociedad Española de Ornitología/BirdLife, C/Melquíades Biencinto 34, 28053 Madrid, Spain 5Present address: Helmholtz Centre for Environmental Research-UFZ, Permoserstraße 15, 04318 Leipzig, Germany *Email: maite.louzao@ufz.de ABSTRACT: An understanding of the distribution and habitat associations of far-ranging marine predators is being increasingly applied to protect these species from anthropogenic threats at sea (e.g. oil spills and fisheries bycatch). Within this framework, this research on Cory’s shearwater Calonectris diomedea integrates vessel-based survey and tracking data to provide 2 distinct, yet complementary, perspectives of the habitats of this species in the western Mediterranean during incubation in June and chick rearing in August of 2007. We used a hierarchical modelling approach to (1) delineate the foraging habitat of the species using vessel-based surveys and (2) identify its feeding habitat based on tracking data within the Information-Theoretic framework. Our habitat modelling analyses suggest that shearwaters respond to complex bio-physical coupling, illustrated by their association with frontal features and elevated ocean productivity. Our models yielded moderate predictions of Cory’s shearwater habitats within 2 distinct spatial scales. At the mesoscale, the foraging range of the species comprised the continental and insular shelf-slope waters of the Iberian Peninsula and the Balearic Islands, between the Gulf of Lions to the north and Cape Palos to the south. At the coarse scale, the tracking data highlighted important feeding areas within this larger foraging range: 3 continental shelf-slope ‘hotspots’—(1) Gulf of Lions, (2) Cape Creus–Barcelona–Ebro Delta and (3) Cape La Nao–Cape Palos; from north to south—as well as the insular shelf-slope areas around the Balearic Islands. These results match previous observations of the foraging range and feeding patterns of the species, and are consistent with the interpretation of the regional oceanography. This study highlights how the integration of tracking and vessel-based survey data can provide a wider understanding of the predictability of aggregation (i.e. hotspots) and the key oceanographic habitats of far-ranging seabirds at multiple spatial scales. Thus, complementary data integration is a step forward in conservation studies of far-ranging marine top predators. KEY WORDS: Calonectris diomedea · Cory’s shearwater · Feeding hotspot · Foraging range · Habitat modelling · Important Bird Area (IBA) · Information-Theoretic approach · Ocean remote sensing · Conservation · Western Mediterranean Full text in pdf format Supplementary material PreviousNextCite this article as: Louzao M, Bécares J, Rodríguez B, Hyrenbach KD, Ruiz A, Arcos JM (2009) Combining vessel-based surveys and tracking data to identify key marine areas for seabirds. Mar Ecol Prog Ser 391:183-197. https://doi.org/10.3354/meps08124Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 391. Online publication date: September 28, 2009 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2009 Inter-Research.

Evolution of a Mediterranean Coastal Zone: Human Impacts on the Marine Environment of Cape Creus

This study presents an integrated analysis of the evolution of the marine environment and the human uses in Cape Creus, a Mediterranean coastal area where intense commercial fisheries and recreational uses have coexisted over the last fifty years. The investigation synthesizes the documented impacts of human activities on the marine environment of Cap de Creus and integrates them with new data. In particular, the evolution of vulnerable, exploited species is used to evaluate the fishing impacts. The effects of area protection through the establishment of a marine reserve in the late 1990s and the potential climate change impacts are also considered. The evolution of the human uses is marked by the increasing socioeconomic importance of recreational activities (which affect species and habitats) in detriment to artisanal and red coral fisheries (which principally affect at a species level). Overall, populations of sedentary, vulnerable exploited species, hard sessile benthic invertebrates, and ecologically fragile habitats, such as seagrass meadows, the coralligenous and infralittoral algal assemblages have been the most negatively impacted by anthropogenic activities. Albeit human uses currently constitute the largest negative impact on the marine environment of Cap de Creus, climate change is emerging as a key factor that could have considerable implications for the marine environment and tourism activities. The establishment of the marine reserve appears to have had little socioeconomic impact, but there is some evidence that it had some positive biological effects on sedentary, littoral fishes. Results demonstrate that the declaration of a marine reserve alone does not guarantee the sustainability of marine resources and habitats but should be accompanied with an integrated coastal management plan.

Spearfishing pressure on fish communities in rocky coastal habitats in a Mediterranean marine protected area

This study constitutes the first empirical investigation in the Mediterranean Sea quantifying in situ the pressure of spearfishing on fish communities in rocky coastal habitats in the Mediterranean. The investigation was carried out in the Cape Creus Marine Protected Area (MPA). Overall, 20 fish species and 1 invertebrate species were identified (three were coastal pelagic and the rest rocky benthic or demersal). In terms of abundance, two omnivorous species made up the 44% of the catch but in terms of weight, the main part (77%) of the catches relied on seven piscivorous (i.e. top-predator) fish (with trophic level values greater than 3.80). With the exception of three fish, the specie's intrinsic vulnerability values ranged between 40 and 90 (out of 100), implying a moderate to very high vulnerability to fishing. Spearfishing mainly targets large individuals measuring more than 30 cm in length. It is estimated that the total annual biomass extracted by spearfishing in the MPA is equivalent to ca. 40% of the total biomass extracted annually by artisanal (commercial) fishing. Overall, results highlight the pressure spearfishing exerts on the reproductive potential of fish species in rocky habitats along the Mediterranean coast, particularly those that are vulnerable (i.e. long lived and slow growing species with low reproductive potential) and have a higher trophic level. Results support the assumption that spearfishing can induce changes in both the trophic structure and the intrinsic vulnerability of taxa in the catch. Considering the biological implications of spearfishing, management should be supported by additional regulations in order to protect species that are vulnerable and have a higher trophic level.

Impacts of recreational boating on the marine environment of Cap de Creus (Mediterranean Sea)

A study was set up in summer 2004 in the marine reserve of Cape Creus (Mediterranean Sea) to estimate the environmental impacts of this activity. The large numbers of recreational boats (most of which are motor powered) that can be found affect the marine environment. In particular, results show that Posidonia oceanica meadows, which constitute an ecologically and vulnerable habitat, are suffering from mechanical damage caused by anchors. Anchoring was the largest threat on the marine environment of the area; the activities conducted by boaters such as sunbathing, swimming, snorkelling and scuba diving had little or negligible environmental impact. Overall, our results indicate that a primary element for coastal management in busy boating areas must be the anchoring of recreational boats and the specific impacts associated with motor craft, such as speed and the discharge of bilge waters.

Analysis and objective mapping of extreme daily rainfall in Catalonia

AbstractThe main objective of this study is to determine the maximum daily precipitation in Catalonia for several established return periods with a high spatial resolution. For this purpose, the maximum daily rainfall annual series from 145 pluviometric stations of the Instituto Nacional de Meteorología (INM) (Spanish Weather Service) in Catalonia have been analyzed. Using the L‐moments method of Hosking, every series has been fitted by the extreme value distribution function of Gumbel. From this fitting, the maximum daily precipitation for each of the pluviometric stations corresponding to return periods between 2 and 500 years, have been determined. Applying the Cressman method, the spatial analysis of these values has been achieved. Monthly precipitation climatological data, obtained from the application of Geographic Information Systems (GIS) techniques, have been used as the initial field for the analysis. The maximum daily precipitation at 1 km2 spatial resolution on Catalonia has been objectively determined by the method employed, and structures with wavelength longer than approximately 35 km can be identified. The results show that places where the maximum daily precipitation values are expected are the zone of Guilleries in the Transversal Range, in the highest zones of the Catalan Pyrenees and Cape Creus zone at the northeastern end of Catalonia and in the south, around the Prelittoral Mountain Range between the Mountains of Prades and Montsià. A good fit between the distribution of minimum values and the driest Catalan areas has been found, the lowest values being on the western end of the Central Basin. Copyright © 2006 Royal Meteorological Society.

The Decline of the Artisanal Fisheries in Mediterranean Coastal Areas: The Case of Cap de Creus (Cape Creus)

This article examines the sociocultural, economic, and environmental causes of the decline of the artisanal fisheries in the rocky coast of Cape Creus (NW Mediterranean) over the past decades. The changes that have occurred over time have favored trawlers, purse-seiners, shellfish fisheries, and tourism activities, to the detriment of artisanal fisheries. This article shows that the establishment of a marine reserve in 1998 could not reverse the observed decline in the artisanal fisheries. This raises the necessity of implementing a fishery management plan integrated into a coastal management plan, which should accompany the habitat protection. These plans could assist in the maintenance and the sustainable development of the artisanal fishing sector in Cape Creus as well as in other Mediterranean coastal areas where artisanal fisheries are also declining.

Geographic, bathymetric and inter-annual variability in the distribution of <i>Liocarcinus depurator</i> (Brachyura: Portunidae) along the Mediterranean coast of the Iberian peninsula

The patterns of occurrence and density of Liocarcinus depurator along the western Mediterranean coast (from Gibraltar to Cape Creus) were measured at depths between 25 and 800 m. Bottom trawl surveys were carried out from 1994 to 2003. For analysis, the area was divided into eight geographic sectors and eight depth intervals. The highest crab occurrences (~80% of trawls) and densities (985 crabs km-2 on average) were found on the shallow muddy continental shelf at depths of 51-100 m with the next highest densities on the upper slope between 201 and 300 m depth (~130 crabs km-2 on average) and occurrence (66% of trawls) between 301 and 400 m. Below 500 m, both crab occurrence and density dropped sharply and L. depurator occurred in less than 10% of all trawls. Thus L. depurator appears to slightly avoid areas on the continental shelf break which are characterised by coarser sediments than on the adjacent continental shelf and slope. Geographically, maximum crab occurrence and density were observed off Valencia (86%, 1187 crabs km-2) and West Alboran (83%, 974 crabs km-2), followed by the Ebro Delta (75%, 502 crabs km-2). Off Alicante L. depurator were relatively common (74% of trawls) but at lower densities (294 crabs km-2 on average). Abundance off the coast of North Catalonia (317 crabs km-2) was equivalent to that off Alicante but the crabs were generally less common (53% of trawls). In general, the highest densities of L. depurator occurred in areas with a wide continental shelf and muddy sediments. During the ten years from 1994 to 2003, densities decreased at a rate of 8 and 4% per annum in shallower water and water deeper than 150 m respectively with a similar decrease in percentage occurrence. This pattern is discussed in relation to the physiological tolerance of the species and reported trends of warming in the Mediterranean Sea.

Male and female carapace shape differences in Liocarcinus depurator (Decapoda, Brachyura): An application of geometric morphometric analysis to crustaceans

Liocarcinus depurator is the most abundant brachyuran by—catch from commercial trawl fisheries along the Spanish Mediterranean coast. Individuals of this species were collected from bottom trawl surveys covering the entire Iberian Mediterranean coast (from Gibraltar to Cape Creus), throughout the species’ depth distribution. Geometric morphometric techniques were used to determine any differences in shape between male and female crabs. Differences in shape not observed with traditional morphometric techniques were detected. Females were found to have a larger base of the abdomen which is discussed in the context of reproductive success.

Simulation and analysis of the mesoscale circulation in the northwestern Mediterranean Sea

Abstract. The large-scale and mesoscale circulation of the northwestern Mediterranean Sea are simulated with an eddy-resolving primitive-equation regional model (RM) of 1/16° resolution embedded in a general circulation model (GM) of the Mediterranean Sea of 1/8° resolution. The RM is forced by a monthly climatology of heat fluxes, precipitation and wind stress. The GM, which uses the same atmospheric forcing, provides initial and boundary conditions for the RM. Analysis of the RM results shows that several realistic features of the large-scale and mesoscale circulation are evident in this region. The mean cyclonic circulation is in good agreement with observations. Mesoscale variability is intense along the coasts of Sardinia and Corsica, in the Gulf of Lions and in the Catalan Sea. The length scales of the Northern Current meanders along the Provence coast and in the Gulf of Lions’ shelf are in good agreement with observations. Winter Intermediate Water is formed along most of the north-coast shelves, between the Gulf of Genoa and Cape Creus. Advection of this water by the mean cyclonic circulation generates a complex eddy field in the Catalan Sea. Intense anticyclonic eddies are generated northeast of the Balearic Islands. These results are in good agreement with mesoscale activity inferred from satellite altimetric data. This work demonstrates the feasibility of a down-scaling system composed of a general-circulation, a regional and a coastal model, which is one of the goals of the Mediterranean Forecasting System Pilot Project. Key words. Oceanography: physical (currents; eddies and mesoscale processes; general circulation)

The Atmospheric Boundary-Layer Structure Within A Cold Air Outbreak: Comparison Of In Situ, Lidar And Satellite Measurements With Three-Dimensional Simulations

A cold-air outbreak over the Mediterranean, associated with a Tramontane event, has been simulated with the atmospheric non-hydrostatic model Meso-NH using a horizontal resolution of 2 km. Results are compared with in situ aircraft, airborne lidar and satellite measurements. On average, the mean and turbulent parameters simulated in the surface layer and mixed layer compared well with in situ measurements. The model was able to reproduce accurately the Foehn effect in the wake of Cape Creus, as well as the occurence of rolls in the coastal region in connection with cloud streets observed with AVHRR. Over the sea, the threshold value of turbulent kinetic energy defining the height of the atmospheric boundary-layer top in the model (defined as 25% of the maximum turbulent kinetic energy in the profile) enables the simulated atmospheric boundary-layer height to match the one retrieved from lidar measurements. Nevertheless, the model did not handle very well the abrupt gradients of all meteorological parameters observed at the top of the atmospheric boundary-layer. Reasons for this are investigated.

Distribution characteristics of pandalid shrimps (Decapoda: Caridea: Pandalidae) along the western Mediterranean Sea

The main characteristics of the bathymetric and zonal distribution of the populations of pandalid shrimps along the western Mediterranean continental shelf and upper slope were studied. Samples were collected by trawling along the Iberian Mediterranean from Gibraltar to Cape Creus in spring 1994, 1995 and 1996. A total of 291 hauls was performed between the depths of 30 and 800 m approximately. A total of nine species of pandalid shrimps was identified in the samples: Chlorotocus crassicornis, Pandalina profunda, Plesionika acanthonotus, P. antigai, P. edwardsii, P. gigliolii, P. heterocarpus, P. martia and Parapandalus narval. A tendency of increasing size with depth was especially marked for P. heterocarpus, P. edwardsii and P. martia. The study areas within the Alborán Sea were characterized by the highest values of abundance of pandalid shrimps, and also by the tendency of species to be present in shallower waters compared with the other study areas.

Estudio de la comunidad de <i>Cystoseira mediterránea</i> en dos localidades de la península del cabo de Creus (Alt Empardà, Nordeste de España)

A survey has been carried out of the Cystoseira mediterranea community from eight samples seasonally collected in two localities of the cape Creus peninsula (N. E. Spain ).The results obtained are related to the environmental conditions and they are compared with those obtained by other authors.