Maite Vázquez-Luis

Changes in amphipod (Crustacea) assemblages associated with shallow-water algal habitats invaded by Caulerpa racemosa var. cylindracea in the western Mediterranean Sea.

The effects of the invasive species Caulerpa racemosa var. cylindracea (hereafter C. racemosa) on amphipod assemblages associated with shallow-water rocky habitats were studied. Two habitats located along the SE Iberian Peninsula were compared; invaded and non-invaded. The results showed that growth of C. racemosa affects habitat structure, influencing the species composition and biomass of macroalgae, and detritus accumulation. In turn, such changes in habitat features affected the associated amphipod assemblages with different ecological requirements. However, the species richness of amphipods was relatively high in both habitats, while the species composition of amphipods changed completely. For example, some species such as Ampithoe ramondi and Hyale schmidti did not colonize invaded habitats, while others such as Apocorophium acutum were favoured by the spread of C. racemosa. Habitat invasion by C. racemosa can have an important influence on biotic assemblages, modifying both habitat structure and the associated fauna, with unknown effects on the overall ecosystem.

Caprellid assemblages (Crustacea: Amphipoda) in shallow waters invaded by Caulerpa racemosa var. cylindracea from southeastern Spain

Growth of the invasive algae Caulerpa racemosa var. cylindracea in shallow habitats may influence the faunal assemblage composition. We studied its effects on caprellid assemblages associated with shallow-water habitats of hard and soft bottoms from the SE Iberian Peninsula (native rocky-bottom algae, C. racemosa from hard and soft bottoms, and Caulerpa prolifera, Cymodocea nodosa and Posidonia oceanica from soft bottoms). Samples were taken in two different sampling periods (September 2004 and March 2005). A total of seven caprellid species were identified, with important differences in their distribution in different habitats. Total abundance of caprellids was very high in March on native algae on hard bottoms, and on C. racemosa on both soft and hard bottoms. On both hard and soft bottoms, abundances of Caprella hirsuta recorded from C. racemosa were low. On the other hand, a higher abundance of other species, namely C. acanthifera, C. santosrosai, Phtisica marina and Pseudoprotella phasma, was recorded from C. racemosa. The results indicate that C. racemosa may have a positive influence on some caprellid species, while seasonal changes are also evident. It is concluded that introduced C. racemosa may serve as a new habitat, promoting and maintaining caprellid populations in shallow Mediterranean habitats.

The tropical caprellid amphipod Paracaprella pusilla: a new alien crustacean in the Mediterranean Sea.

Paracaprella pusilla Mayer (Fauna und Flora des Golfes von Neapel 17:1–55, 1890), originally described from Brazil, is one of the most abundant caprellid amphipod species in tropical and subtropical seas around the world. During a survey of caprellid amphipods from marinas along the Balearic Island (Western Mediterranean Sea) carried out between November 2011 and August 2012, we found two established populations of P. pusilla in Mallorca and Ibiza, respectively. So far, its occurrence in European waters was reported only from southwestern Spain in 2010. This record represents a northward range expansion of the species’ distribution, which is found for the first time in the Mediterranean. This is also the first record of the genus Paracaprella in the Mediterranean Sea. The most probable introduction vector was ship fouling. We also found the invasive caprellid Caprella scaura Templeton (Trans Entomol Soc Lond 1:185–198, 1836) in Mallorca and Menorca, which is recorded for the first time in the Balearic Islands, confirming its rapid expansion along the Mediterranean. When comparing reproductive traits between both alien species, we found that P. pusilla has a higher fecundity than C. scaura for the same female size. Taking into account this evidence, the species may be expected to appear in other Mediterranean and adjacent areas.

Does the invasion of Caulerpa racemosa var. cylindracea affect the feeding habits of amphipods (Crustacea: Amphipoda)?

maite va’ zquez-luis, pablo sanchezQ1 jerez and just t. bayle-sempere I.E.O., Centre Oceanogràfic de les Balears, Moll de Ponent s/n, 07015 Palma de Mallorca, Spain, Centro de Investigación Marina de Santa Pola (CIMAR), Ayto. de Santa Pola y Universidad de Alicante, Torre d’Enmig s/n, Cabo de Santa Pola, Alicante, Spain, Departamento de Ciencias del Mar y Biologı́a Aplicada. Edificio Ciencias V. Universidad de Alicante, POB. 99, E-03080 Alicante, Spain

Influence of boat anchoring on Pinna nobilis: a field experiment using mimic units

Anchoring by recreational boats causes several different effects on marine habitats and species. The influence of boat anchoring on the Mediterranean endemic bivalve Pinna nobilis was assessed experimentally in the field by deploying non-biological mimic units of the bivalve around the islands of Mallorca and Malta. In each of these two localities, two study areas having different levels of boat anchoring activities, namely, ‘control’ (no anchoring allowed) and ‘affected’ (anchoring allowed), were used for the field experiment. A significant number of P. nobilis mimic bivalves were affected by boat anchoring; the influence was three times higher at anchoring sites than in control areas. Boat anchoring also had an adverse effect on Posidonia oceanica meadows, with seagrass cover, shoot density and global density being lower in the anchoring areas. Moreover, lower values of natural P. nobilis density and size classes were recorded from the anchoring areas.

The Pen Shell, Pinna nobilis

The pen shell Pinna nobilis (also known as the fan mussel) is an endemic bivalve of the Mediterranean Sea. Threatened by human activities, it has been listed as an endangered and protected species under the European Council Directive 92/43/EEC since 1992. The ecological role of this species is of importance because it filters and retains large amounts of organic matter from suspended detritus contributing to water clarity. In addition, as a hard substrate in the soft-bottom seafloor, it provides a surface that can be colonized by other (floral and faunal) benthic species. Here, we provide an overview of all available published studies on the pen shell, compiling available data and summarizing current knowledge on the conservation status and viability of populations over the full range of the Mediterranean Basin. Additionally, we discuss the different practices in applied methodology and identify gaps and new research areas in order to render conservation programmes of the species more effective.

The Pen Shell, Pinna nobilis: A Review of Population Status and Recommended Research Priorities in the Mediterranean Sea

The pen shell Pinna nobilis (also known as the fan mussel) is an endemic bivalve of the Mediterranean Sea. Threatened by human activities, it has been listed as an endangered and protected species under the European Council Directive 92/43/EEC since 1992. The ecological role of this species is of importance because it filters and retains large amounts of organic matter from suspended detritus contributing to water clarity. In addition, as a hard substrate in the soft-bottom seafloor, it provides a surface that can be colonized by other (floral and faunal) benthic species. Here, we provide an overview of all available published studies on the pen shell, compiling available data and summarizing current knowledge on the conservation status and viability of populations over the full range of the Mediterranean Basin. Additionally, we discuss the different practices in applied methodology and identify gaps and new research areas in order to render conservation programmes of the species more effective.

Comparison of epifaunal assemblages between Cymodocea nodosa and Caulerpa prolifera meadows in Gran Canaria (eastern Atlantic)

Epifaunal invertebrates are sensitive to changes in the identity of the dominant host plant, so assessing differences in the structure of epifaunal assemblages is particularly pertinent in areas where seagrasses have been replaced by alternative vegetation (e.g. green seaweeds). In this study, we aimed to compare the diversity, abundance and structure of epifaunal assemblages, particularly amphipods, between meadows dominated by the seagrass Cymodocea nodosa and the green rhizophytic algae Caulerpa prolifera on shallow soft bottoms of Gran Canaria Island, determining whether patterns were temporally consistent between two times. The epifaunal assemblage structure (abundance and composition) consistently differed between both plants, those assemblages associated with C. prolifera-dominated beds being more diverse and abundant relative to C. nodosa meadows. Amphipods constituted 70% of total crustaceans for the overall study, including 37 species belonging to 16 families. The amphipod abundance was 3 times larger in C. prolifera-dominated beds than in C. nodosa meadows. We detected species-specific affinities; for example, Microdeutopus stationis, Dexamine spinosa, Aora spinicornis, Ischyrocerus inexpectatus and Apherusa bispinosa were more abundant in C. prolifera-dominated beds; while the caprellid Mantacaprella macaronensis dominated in C. nodosameadows. However, some species, such as Pseudoprotella phasma and Ampithoe ramondi, were found in both habitats with varying abundances between times.

S.O.S. Pinna nobilis: A Mass Mortality Event in Western Mediterranean Sea

A mass mortality event impacting the bivalve Pinna nobilis was detected across a wide geographical area of the Spanish Mediterranean Sea (Western Mediterranean Sea) in early autumn 2016. Underwater visual censuses were conducted across several localities separated by hundreds of kilometres along the Spanish Mediterranean coasts and revealed worrying high mortality rates reaching up to 100% in the center and southernmost coasts of the Iberian Peninsula including Balearic Islands. Populations on the northern coasts of the Spanish Mediterranean Sea seemed to be unaffected (Catalonian region). Histological examination of affected individuals revealed the presence of a haplosporidan-like parasite within the digestive gland being probably the pathogen that causes this mortality. The present mass mortality event has spread rapidly, causing high mortality rates in infected populations. Taking into account the degree of impact, the geographic extent, and the high probability that the infection is still in a spreading phase; this might be considered the largest mass mortality event ever registered for P. nobilis up to date, forcing this emblematic bivalve into a critical viability status over hundreds of kilometers of coast.

Human Stressors Are Driving Coastal Benthic Long-Lived Sessile Fan Mussel Pinna nobilis Population Structure More than Environmental Stressors

Coastal degradation and habitat disruption are severely compromising sessile marine species. The fan shell Pinna nobilis is an endemic, vulnerable species and the largest bivalve in the Mediterranean basin. In spite of species legal protection, fan shell populations are declining. Models analyzed the contributions of environmental (mean depth, wave height, maximum wave height, period of waves with high energy and mean direction of wave source) versus human-derived stressors (anchoring, protection status, sewage effluents, fishing activity and diving) as explanatory variables depicting Pinna nobilis populations at a mesoscale level. Human stressors were explaining most of the variability in density spatial distribution of fan shell, significantly disturbing benthic communities. Habitat protection affected P. nobilis structure and physical aggression by anchoring reveals a high impact on densities. Environmental variables instead played a secondary role, indicating that global change processes are not so relevant in coastal benthic communities as human-derived impacts.