Does the invasion ofCaulerpa racemosavar.cylindraceaaffect the feeding habits of amphipods (Crustacea: Amphipoda)?

Abstract

<jats:p>Ecological interactions involving introduced seaweeds constitute an important research gap, since they could alter the trophic dynamics of native populations, but indirect effects on trophic levels are poorly known. The seaweed<jats:italic>Caulerpa racemosa</jats:italic>is one of the most notable invaders in the Mediterranean Sea. It is well known that<jats:italic>C. racemosa</jats:italic>modifies the amphipod community with respect to native habitats, but nothing is known regarding the common use of the same trophic resources. Therefore, the aim of this study was to assess if the feeding habits of amphipods associated with algal habitats are affected by the spread of the invasive<jats:italic>C. racemosa</jats:italic>, through stomach content analysis of amphipods living in both native and invaded seaweed assemblages. A total of 240 specimens of 14 species of amphipods were examined. Ten species were present in both studied habitats (native and invaded), while two were exclusive to native and invaded habitats, respectively. Ten individuals of each species at each habitat were selected and their gut contents were examined. A total of 11 different items was found in the gut contents: detritus; vegetal detritus; algae; animal tissue; Oligochaeta; Polychaeta; Foraminifera; Crustacea; Sipuncula; diatoms; and non-identified items. The expansion of<jats:italic>C. racemosa</jats:italic>into the native algal community changes the feeding habits of herbivorous amphipods, since their preferred food (epiphytic algae) is not available in the new habitat produced by<jats:italic>C. racemosa</jats:italic>. This community change occurs because of the presence of caulerpenyne in<jats:italic>C. racemosa</jats:italic>, which retards the growth of epiphytic algae. Nevertheless, other species are not affected or benefited by the invasion, such as detritivorous species whose main food source and habitat remains available. Altogether, slight changes in the trophodynamism of amphipod assemblages have been detected, which are not seen as relevant in an initial stage. However, they might be promoting some indirect effects in the energetic budget of populations, which may affect the life history. Further studies on food-web interactions in the ecosystems affected by invasive species are necessary.</jats:p>

Dietary analysis of caprellids Caprella penantis and Caprella grandimana (Crustacea: Amphipoda) in southern Spain

“…Detritus was always the greatest contributor to the diets of these caprellids, which was consistent with several studies (Jeong et al 2012;Vazquez-Luis et al 2013;GuerraGarcía et al 2014). Detritus plays a key role in marine invertebrate food webs and trophic pathways in marine ecosystems (Valiela 1995).…”

“…We suggest that C. penantis and C. grandimana should be considered omnivores based on these definitions. Vazquez-Luis et al (2013) considered C. grandimana to be an omnivore and Guerra-García and Tierno de Figueroa (2009) referred to both species as opportunistic.…”

“…The gut examination methodology used in this study has been applied previously by entomologists (Tierno de Figueroa et al 2006) and was successfully used for amphipods (Navarro-Barranco et al 2013;Vazquez-Luis et al 2013;Guerra-García et al 2014). Gut content analyses are an accurate direct indicator, which is an advantage compared with indirect indicators, such as stable isotope and fatty acid analyses.…”

“…Gut content analyses are an accurate direct indicator, which is an advantage compared with indirect indicators, such as stable isotope and fatty acid analyses. However, a combination of these methods, together with mouthpart morphological studies and behavioral observations, is needed to obtain complete data on caprellid feeding habits and food web interactions in ecosystems where they dominate (Vazquez-Luis et al 2013), particularly when studying seasonal variations. Although our understanding of amphipod feeding habits has increased during the last few years, several authors have pointed out that qualitative and quantitative characterizations of the amphipod species-specific trophic ecology are needed to better understand their potential role in the trophic dynamics, structure, and nutrient fluxes in marine ecosystems (Graeve et al 2001;Jeong et al 2012).…”

Diets of peracarid crustaceans associated with the orange coral Astroides calycularis in southern Spain

“…Sarvala & Uitto, 1991) and show a wide range of feeding habits (Conradi & Cervera, 1995). They also constitute an important food source for a large variety of marine predators (Vázquez-Luis et al, 2013); hence playing a key role in energy flow through food webs (Guerra-García et al, 2014). Consequently, the main objective of the present study is to explore if peracarids associated with A. calycularis feed on the host coral's tissues, in an effort to highlight the nature of the association.…”