Bythocaris cosmetops (Decapoda: Caridea: Hippolytidae) in the western Mediterranean Sea

The capture of the species Bythocaris cosmetops in the Alboran Sea (southern Spain, western Mediterranean Sea), previously known from only two specimens from the Atlantic, Sierra Leone (south-west Africa) and the northern Bay of Biscay (north-west Europe), represents the first record of the genus and species in the Mediterranean Sea and Iberian Peninsula (south-west Europe). New data on morphology, biology and habitat are provided and discussed.Postprint0,000

Damage assessment and survival estimates in the wedge clam (Donax trunculus) caught by mechanical dredging in the northern Alboran Sea

This paper describes the impact of dredging on populations of the wedge clam (Donax trunculus) at two sites along the northern Alboran coast. Damage was assessed by quantifying shell and foot damage on commercial clams caught with mechanical dredges. Survival experiments were carried out to assess their survival capacity after 24 h purification treatment and 72 h cold storage, which represents an issue of great interest for fisheries research, management and marketing. Overall, 2.4% of wedge clams suffered any type of damage, including chipped edges and scratched valves. Higher proportions of shell-damaged individuals were positively correlated to bottom features (e.g. gravel content in sediment). Moreover, higher towing speed significantly increased shell damage. Analyses of shell damage areas revealed that the anterior dorsal and ventral parts of the shell are the most vulnerable to dredging. A total of 15.9% of individuals showed damage on the foot, which seems not to affect their survival. The incidence of foot damage was mostly linked to sublethal predation, reflected in a positive correlation between the proportion of foot-damaged individuals and biomass of decapod crustaceans in the fishing ground. Finally, D. trunculus exhibited very low mortality rates after 24 h purification treatment (0.2–0.4%) and 72 h cold storage (0.3–3.2%). The survival rate at the end of the experiment was high (>96%), with the highest mortality observed 96 h after the fishing day. No correlations were found between mortality rates and bottom type or towing speed.Postprin

Molluscan assemblages associated with photophilous algae in the Alboran sea (western Mediterranean Sea)

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Posidonia oceanica (L.) Delile in its westernmost biogeographical limit (northwestern Alboran Sea): Meadows characterisation, phenology and flowering events

Posidonia oceanica is a Mediterranean endemic seagrass species that forms meadows covering ca. 2.5–4.5 millions of hectares, representing ca.25 % of the infralittoral and shallow circalittoral (down to 50m) bottoms of the Mediterranean. This seagrass is considered a habitat-engineer species and provides an elevated number of ecosystem services. In addition the Marine Strategy Framework Directive (MSFD, 2008/56/EC) includes seagrass like elements to evaluate the “Good Environmental Status” of the European coasts. Information about their phenological characteristic and structure of the meadows is needed for indicator estimations in order to establish their conservation status. The studied meadows are located in the westernmost limit of the P. oceanica distribution (North-western Alboran Sea) in the vecinity of the Strait of Gibraltar, an Atlantic-Mediterranean water transition area. Four sites were selected from East to West: Paraje Natural de Acantilados de Maro-Cerro Gordo (hereafter Maro), Special Area of Conservation “Calahonda” (hereafter Calahonda), Site of Community Importance Estepona (hereafter Estepona) and Punta Chullera (hereafter Chullera) where P. oceanica present their westernmost meadows. Phenological data were recorded from mid November to mid December in P. oceanica patches located at 2 – 3 m depth. At each site three types of patches (patch area 2 m2, large patches) were sampled. At each patch and site, 3 quadrants of 45 x 45 cm were sampled for shoot and inflorescences density measurements. In each quadrant, 10 random shoots were sampled for shoot morphology (shoot height and number of leaves). Shoot and inflorescences densities were standardized to squared meters. All the studied P. oceanica meadows develop on rocks and they present a fragmented structure with a coverage ranging between ca. 45% in Calahonda and Estepona and ca. 31% in Maro. The meadows of Chullera are reduced to a few small - medium patches with areas ranging between 0.5-1.5 m2 (Fig. 1). The meadows of Chullera and Estepona presented similar values of shoot density (ca. 752 – 662 shoots m-2, respectively) and leaf height (ca. 25 cm). Similarly, the Calahonda and Maro meadows also showed similar values of shoot density (ca. 510 – 550 shoots m-2, respectively) but displaying lower values than those of sites located closer to the Strait of Gibraltar. Regarding patch sizes and leaf height, the longest leaves (ca. 25 cm) were found in medium and large patches, but the number of leaves per shoot were higher in the small and the medium size patches (ca. 6.3 leaves per shoot). Flowering was only detected at the Calahonda meadows with maximum values of ca. 330 inflorescences m-2 (115.2 ± 98.2 inflorescences m-2, n= 9; mean ± SD) (Fig.1). Inflorescence density was not significant different among patches of different sizes. In the Alboran Sea and unlike the studied meadows, extensive beds of P. oceanica occur at the National Park of Cabo de Gata (northeastern Alboran Sea), but from east to west (Strait of Gibraltar), meadows are gradually fragmenting and their depth range decrease from 30m to 2m depth between Cabo de Gata and Chullera, respectively. Probably, the Atlantic influence and the characteristic oceanographic conditions of the Alboran Sea (i.e., higher turbidity, higher water turbulence) represent a developmental limiting factor for P. oceanica at higher depths. Similarities between the meadows located closer to Strait of Gibraltar (Chullera and Estepona) were detected as well as between those more distant (Calahonda and Maro). The first ones showed higher values of shoot densities and leaf heights than the formers, which could be relating to the higher hydrodynamic exposure found at Chullera and Estepona meadows. Regarding flowering events, sexual reproduction in P. oceanica is not common in different locations of the Mediterranean Sea. The available information seems to indicate that flowering represent an irregular event and it is related to high seawater temperature. In fact, the flowering episodes that occurred in Calahonda in November 2015, match with the warmest year ever recorded. This is the third flowering event registered in these meadows located close to the westernmost distributional limit of P. oceanica (Málaga, Alboran Sea), which could indicates that these meadows presents a healthy status. Furthermore, the absence of significant differences in relation to inflorescence density between patches of different sizes may be indicating that the fragmentation does not necessarily influence on the flowering of this seagrass species

Molluscs as bioindicators of the regression of a Zostera marina bed in southern Spain

Seagrass beds are experiencing a sharp decline worldwide and, unfortunately, a continued decrease is expected, mainly due to anthropogenic influence, with negative repercussions for coastal biodiversity. One of these declining seagrasses is Zostera marina L. which is the most widespread in the northern hemisphere (North America, Europe and Asia). One of the most recent observed cases of eelgrass decline occurred in the Special Area of Conservation “Acantilados de Maro - Cerro Gordo” (southern Spain) between 2005 and 2007. These eelgrass beds were probably the deepest ones (5–18 m depth) in Europe and supported a highly diverse associated fauna (Rueda et al., 2009). Different methods have been designed for evaluating ecological integrity or condition status of coastal waters. In general, there is an increasing interest in developing assessment tools for different physicochemical or biological elements of the ecosystems. Taking this into account, what might be the characteristics of a good ecological indicator? In Europe, and within the Water Framework Directive (Directive 2008/56/EC), biological elements are limited to composition, abundance (and biomass) of phytoplankton, other aquatic flora, benthic invertebrate fauna, and fishes. The data used to quantify these biological elements describe distributions/gradients, ratios, biodiversity indices and classification schemes. Environmental science must complement the structural ecosystem properties through an approach towards the ecosystem function and dynamics. In this way, trophic webs constitute probably an appropriate type of measurement of the ecosystem function. Molluscs constitute ca. 25% of the benthos and their dynamics have been shown to reflect the dynamics of the whole community. Therefore, we analyzed the changes in the molluscan taxocoenosis associated with the regression of a Zostera marina bed from the SAC of Acantilados de Maro - Cerro Gordo from 2005 to 2009. We analyzed changes in biotic variables: species richness, abundance, diversity index, biotic indexes and trophic diversity of the molluscan assemblage, and abiotic variables: grain size and percentage of organic matter in sediment. The aim was to check which of these indicators expressed better the environmental changes caused by the regression of the eelgrass bed. Species richness was the best indicator for showing loss of species and the Trophic Index (Danovaro et al., 2004) was the indicator that better expressed the drastic change of the assemblage, with a strong reduction of the trophic groups. Regarding biotic indexes, AMBI, MAMBI and MEDOCC, the absence of eutrophication makes these indicators less accurate to reflect the environmental change caused by the loss of the eelgrass bed. In fact, the best descriptor for this event would be the integrity of seafloor, because the regression of the eelgrass bed changes completely the bottom landscape. The loss of seagrasses and its effects are going to be one of the important topics in future scientific studies due to this continuous declining trend, so tools allowing us to anticipate this threat are becoming essential. In southern Spain, protection of seagrasses is urgently needed for preserving not only the beds but also the diverse communities associated with them

Spatial and temporal distribution of the larval fish assemblage of the bay of Malaga (Western Mediterranean).

The REMALA Project studied the spatial and temporal distribution of the larval fish assemblage over an annual cycle, in the bay of Malaga (Northwest Alboran Sea). More than 80 larval fish taxa were identified in the study area highlight its high biodiversity, jointly with the presence of larvae of species with a high commercial interest, such as e.g. Sardina pilchardus, Engraulis encrasicolus or Pagrus pagrus. The larval fish assemblage in the bay of Malaga appears to be a relatively stable community with some intra-annual and onshore-offshore variability.Versión del edito

Asociaciones de crustáceos decápodos ligadas a fondos de algas fotófilas dominadas por Stypocaulom scoparium (Linnaeus) Kützig en el Mar de Alborán

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Spatial distribution of fishing fleets in a future Fishery Protected Area in the Malaga Bay (Northwestern Alboran Sea).

Málaga Bay is an important area from the icthyoplankton viewpoint where it is possible to find more than 80 species belonging to 68 genera and 41 families. Furthermore, the bay is an essential spawning and nursery area for many species of commercial interest, such as sardine (Sardina pilchardus), anchovy (Engraulis encrasicolus), Atlantic horse-mackerel (Trachurus trachurus), Mediterranean horse-mackerel (T. mediterraneus) or hake (Merluccius merluccius). Local bottom trawl, purse seine and polyvalent artisanal fleets, have traditionally fished in this bay targeting on many species of fishes, crustaceans and molluscs. An ecological and fisheries study was undertaken in 2013 and 2014 with the purpose of assessing the suitability of Málaga Bay as a Fishery Protected Area. One of the important aspects taken into account is the spatial distribution of the fishing effort to evaluate its impact in the area. The findings achieved in this study are essential and valuable information for a proper fisheries management integrating the ecosystem-based approach into fisheries advice. The results show that Málaga Bay supports a heavy fishing pressure in all the fishing grounds which may affect both its commercial resources and sedimentary habitats.Versión del edito

New Marine Protected Areas for the benthic biodiversity conservation in the Alboran Sea

The Alboran Sea displays oceanographic and biogeographical highlighting characteristics that promote one of the most important areas for marine biodiversity of the Mediterranean and European waters. Nevertheless, anthropogenic activities are threatening some coastal habitats that are highly important for species currently threatened or in danger of extinction (e.g. Patella ferruginea, Pinna nobilis). Consequently, new marine protected areas have been recently declared in the northern Alboran Sea in order to preserve species, habitats and ecosystems. The Sites of Community Importance “Calahonda” (Málaga) and “Acantilados y Fondos Marinos de Calahonda- Castell de Ferro” (Granada) contain Mediterranean characteristic habitats (e.g. Posidonia oceanica beds, coralligenous communities) with an important Atlantic faunistic component, as well as with protected species and others that are extremely rare or absent in other European locations. In addition, ecological processes that are representative of the Alboran Sea (e.g. upwellings, high productivity) take place in these areas, supporting the development of local artisanal fisheries.Versión del edito