Peracarid assemblages of Zostera meadows in an estuarine ecosystem (O Grove inlet, NW Iberian Peninsula): spatial distribution and seasonal variation

Abstract

The Galician rias are singular and complex estuarine systems of great economic importance. Seagrasses are key elements of the ecosystem and favor the maintenance of high species diversity in benthic communities. Nevertheless, the ecological role of seagrass meadows in the Galician rias has been only partially assessed. Peracarid crustaceans are an important component of soft-bottom faunas and have great importance for the structure of benthic assemblages. In this work, species diversity, patterns of distribution and seasonal fluctuations of peracarids (Crustacea, Peracarida) are studied in estuarine sediments colonized by two species of Zostera (Z. marina and Z. noltii) at the O Grove inlet (Ría de Arousa, Galicia, NW Iberian Peninsula). The spatial distribution of peracarid assemblages was characterized by high numerical dominances due to a few species, particularly tanaidaceans. The temporal study at a Z. marina meadow showed a strongly seasonal pattern defined by great fluctuations of the amphipod population, the latter being the dominant group in abundance and number of species. The highest numbers of species and individuals were observed in September, with minimum values in March. Analyses pointed out a high correlation among the granulometric features of the studied bottoms and the faunistic attributes. Nevertheless, the presence of the seagrasses should influence in a major way the hydrodynamic and sedimentary features of the habitat and utterly the spatial and temporal patterns observed in the peracarid assemblage in the O Grove inlet.

Apseudopsis adami, a new species of tanaidacean (Crustacea: Peracarida) from the NW Iberian Peninsula: postmarsupial development and remarks on morphological characters

“…Guţu (2002) proposed a number of characters as useful for identification of species of the genus Apseudopsis (as Apseudes Leach 1814), revalidating species synonymized with A. acutifrons by Lang (1955), but included characters that vary intraspecifically between instars (see above, and Esquete et al 2011), and thus are valid solely for adults. Among the characters that remain stable throughout the life history of A. adami sp.…”

“…Several characters have been proposed as indicative of the developmental stage of an individual in tanaidacean species, e.g., the number of segments of the antennular and uropodal flagella (Vengayil et al 1988), the presence of hyposphenia (Guţu 2002(Guţu , 2006 and the ornamentation of the mandibular palp (Esquete et al 2011). Although the number of segments and the type of ornamentation in each stage varies from one species to another, these characters are stable within each developmental stage.…”

“…The genus is common and widely distributed on the shallow sedimentary bottoms of the North Atlantic and the Mediterranean Sea (see Guţu 2002 (as Apseudes); Bamber et al 2009;Bamber 2011). The only species known to date from the Atlantic coasts of Europe is Apseudopsis latreillii (Milne-Edwards 1828), which is considered common to abundant and therefore represents an important component of soft bottom assemblages (Riggio 1996;De-la-OssaCarretero et al 2010 [as Apseudes]; Bamber 2011; Esquete et al 2011Esquete et al , 2012.…”

Ecology and systematics of a new species of Uromunna (Crustacea: Isopoda) from Spanish eelgrass beds

“…Eelgrasses, in particular, have a great capacity to provide food resources, substrate and shelter to many taxonomic groups (Fredette et al 1990;Boström and Mattila 1999;Hasegawa et al 2008). Recent sampling of peracarid crustaceans in Spanish seagrass habitats (Esquete et al 2011) found several species of the asellotan isopod family Munnidae. Species of Munnidae have been described or reported in eelgrasses, such as Uromunna brevicornis (Thomson, 1946) (Poore 1984), Uromunna peterseni (Pires, 1985), Uromunna reynoldsi (Frankenberg and Menzies, 1966) (Kensley et al 1995).…”

“…Most species of Uromunna live in shallow, brackish waters, where they can be locally found in high densities (e.g. Esquete et al 2011). Nevertheless, the geographic distribution of Uromunna species still is poorly known, most records being restricted to the species' type locality.…”