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Hyperbenthic Mysidae Haworth, 1825 (Peracarida, Mysida) from the continental shelf of the northern Adriatic Sea
Abstract
Species composition, distribution, and spatio-temporal dynamics of hyperbenthic Mysidae Ha-worth, 1825 (Peracarida, Mysida) were studied on the continental shelf of the northern Adriatic Sea. A total of seven species was collected: Anchialina agilis, Erythrops elegans, Haplostylus lobatus, Leptomysis gracilis, Mysidopsis angusta, Mysidopsis gibbosa, and Paraleptomysis banyulensis. The hyperbenthic mysid assemblage was dominated by A. agilis, E. elegans, and L. gracilis, in terms of frequency of occurrence, abundance, and biomass. Notable seasonal fluctuations in the abundance of the catches were observed, with a minimum reached in the period July-September, probably due to the species' life cycles as well as to environmental factors, such as the presence of mucilaginous aggregates close to the bottom.
... P < 0.001). The same test highlighted a significant trend for amphipods (G = Se encontraron hembras con bolsa marsupial bien desarrollada de varias especies (e.g., los mísidos E. elegans y L. gracilis) en dos periodos distintos del año (Ligas et al. 2007). Cartes et al. (Table 2. Production and production/biomass ratio (P/B) estimations of the 13 eucarid and peracarid target species. ...
... P << 0.01; T = 4.00, P < 0.05), mientras que los mísidos y los decápodos lo hicieron en U. presencia de naufragios y plataformas puede modificar las comunidades bénticas locales (Hall et al. 1993, Jennings y Kaiser 1998, Ball et al. 2000, Pranovi et al. 2001), varios estudios han indicado que sus efectos sobre las comunidades bénticas son localizados y menores (Currie y Isaacs 2005). Desde la expedición Hvar (Hoenigman 1968), este estudio es la primera contribución al conocimiento de las comunidades bénticas de crustáceos del Mar Adriático con especial énfasis en el suprabentos (Ligas et al. 2007). Los crustáceos bénticos son considerados una de las principales fuentes de alimento para los mayores predadores marinos como los peces; por tanto, el conocimiento de su composición específica y dinámica de producción secundaria es de importancia económica para las comunidades bentónicas explotadas por las pesquerías (Cartes y Sorbe 1999). ...
... CL = cephalothorax length. Since the Hvar expedition (Hoenigman 1968), the present study is the first contribution to the knowledge of Adriatic Sea crustacean benthic assemblages with special reference to suprabenthos (Ligas et al. 2007 ). Benthic crustaceans are considered one of the main food source for marine top predators such as fish; hence, knowledge of their species composition and their secondary production dynamics assumes an economic importance in those benthic communities subject to fisheries exploitation (Cartes and Sorbe 1999). ...
Towing gears are known to produce several kinds of effects on benthic ecosystems. As small organisms and benthic species with faster growth rates and shorter life histories can withstand the fishing mortality and benefit from reduced competition or predation, trawl fishing can enhance their proliferation. Thus, trawl fishing can lead to biomass loss and production increase, since smaller specimens are more productive than bigger ones. In the present study we evaluate the effects, if any, of trawling on benthic crustacean macrofaunal production rates. Sampling was carried out in two neighbouring sites in the central Adriatic Sea (central Mediterranean), one affected by fishing activity and one not. Production and production/biomass (P/B) ratio of 13 species of peracarid and eucarid crustaceans were estimated using the Hynes sizefrequency method. Estimates measured at both sites were compared in order to test the hypothesis that higher production and P/B values should occur in the fished area rather than in the unfished one. Our results indicated that the effects on the species are more complex than expected in regard to this hypothesis, and that they depend on the ecological and behavioural characteristics of the selected species.
... P < 0.001). The same test highlighted a significant trend for amphipods (G = Se encontraron hembras con bolsa marsupial bien desarrollada de varias especies (e.g., los mísidos E. elegans y L. gracilis) en dos periodos distintos del año (Ligas et al. 2007). Cartes et al. (Table 2. Production and production/biomass ratio (P/B) estimations of the 13 eucarid and peracarid target species. ...
... P << 0.01; T = 4.00, P < 0.05), mientras que los mísidos y los decápodos lo hicieron en U. presencia de naufragios y plataformas puede modificar las comunidades bénticas locales (Hall et al. 1993, Jennings y Kaiser 1998, Ball et al. 2000, Pranovi et al. 2001), varios estudios han indicado que sus efectos sobre las comunidades bénticas son localizados y menores (Currie y Isaacs 2005). Desde la expedición Hvar (Hoenigman 1968), este estudio es la primera contribución al conocimiento de las comunidades bénticas de crustáceos del Mar Adriático con especial énfasis en el suprabentos (Ligas et al. 2007). Los crustáceos bénticos son considerados una de las principales fuentes de alimento para los mayores predadores marinos como los peces; por tanto, el conocimiento de su composición específica y dinámica de producción secundaria es de importancia económica para las comunidades bentónicas explotadas por las pesquerías (Cartes y Sorbe 1999). ...
... CL = cephalothorax length. Since the Hvar expedition (Hoenigman 1968), the present study is the first contribution to the knowledge of Adriatic Sea crustacean benthic assemblages with special reference to suprabenthos (Ligas et al. 2007 ). Benthic crustaceans are considered one of the main food source for marine top predators such as fish; hence, knowledge of their species composition and their secondary production dynamics assumes an economic importance in those benthic communities subject to fisheries exploitation (Cartes and Sorbe 1999). ...
Towing gears are known to produce several kinds of effects on benthic ecosystems. As small organisms and benthic species with faster growth rates and shorter life histories can withstand the fishing mortality and benefit from reduced competition or predation, trawl fishing can enhance their proliferation. Thus, trawl fishing can lead to biomass loss and production increase, since smaller specimens are more productive than bigger ones. In the present study we evaluate the effects, if any, of trawling on benthic crustacean macrofaunal production rates. Sampling was carried out in two neighbouring sites in the central Adriatic Sea (central Mediterranean), one affected by fishing activity and one not. Production and production/biomass (P/B) ratio of 13 species of peracarid and eucarid crustaceans were estimated using the Hynes size-frequency method. Estimates measured at both sites were compared in order to test the hypothesis that higher production and P/B values should occur in the fished area rather than in the unfished one. Our results indicated that the effects on the species are more complex than expected in regard to this hypothesis, and that they depend on the ecological and behavioural characteristics of the selected species.
... In the Mediterranean basin most studies on suprabenthos have focused on the surf zone and on the deep sea (Cartes, 1998;Cartes and Sorbe, 1999;San Vicente and Sorbe, 1999;Cartes et al., 2001;Fanelli et al., 2009b), whereas the continental shelf suprabenthic assemblages have rarely been investigated, despite their productivity for fisheries Ligas et al., 2007;Fanelli et al., 2009c). Coastal and estuarine environments are typically subjected to important fluctuations that are associated to a variety of oceanographic processes, such as changes in water masses (temperature, salinity, etc.), changes in river inputs, pulses of organic matter derived from primary production and vertical fluxes (Grémare et al., 1997), that have a direct influence on the dynamics of the suprabenthos (Cartes et al., , 2009. ...
... Despite the marked oligotrophy of the study area, suprabenthos was quite abundant and diversified if compared to the Catalan Sea and the northern Adriatic Sea (Ligas et al., 2007) and more similar in terms of diversity to extra-Mediterranean temperate areas (SW France and Netherlands: Mees et al., 1995;English Channel: Dauvin et al., 2006). Ligas et al. (2007) found similar dominant species in the northern Adriatic samples. ...
... Despite the marked oligotrophy of the study area, suprabenthos was quite abundant and diversified if compared to the Catalan Sea and the northern Adriatic Sea (Ligas et al., 2007) and more similar in terms of diversity to extra-Mediterranean temperate areas (SW France and Netherlands: Mees et al., 1995;English Channel: Dauvin et al., 2006). Ligas et al. (2007) found similar dominant species in the northern Adriatic samples. ...
Meso-scale spatial variability of coastal suprabenthic communities inhabiting muddy bottoms at 50e80 m depth in three gulfs of northern Sicily (Western Mediterranean) was here investigated. Although similar as concerns the hydrological and oceanographic conditions, the three areas, that encompass a large portion of the continental shelf (135 km), are characterized by different geo-morphological features. In addition, they are subjected to different trawl fishery pressures. The Gulf of Castellammare is a semi-enclosed bay, where the trawling activity has been banned since 1990. The Gulf of Termini Imerese and the Gulf of Sant'Agata are open areas, subjected to high trawl fishing intensity. In terms of density, gammarid amphipods showed differences among the three gulfs; in terms of biomass, cumaceans and amphipods were more abundant in the Gulf of Castellammare than in the other two areas. Multivariate analyses provided evidence for separation of suprabenthic assemblages between the Gulf of Castellammare and the other two gulfs. The Gulf of Castellammare seemed to host the most diversified and stable community according to a-and b-diversity indices. In the same way the low value of d 13 C vs. d 15 N correlation found in the gulf of Castellammare, which evidences the occurrence of several food sources, supports the idea of a higher stability in the semi-enclosed, trawl-ban area. In the other two areas d 13 C vs. d 15 N correlations were high, suggesting the existence of a pelagic source sustaining the suprabenthic communities. This is also confirmed by the lower d 13 C concentrations found in suprabenthic species. Taking into account the homogeneous oceanographic conditions among gulfs, other factors, such as geo-morphology and trawling pressure should be involved in the observed differences among the three areas in terms of assemblage structure, diversity, and trophodynamics of suprabenthic communities.
... The suprabenthos or hyperbenthos communities are macrofaunal assemblages of smallsized organisms living in the benthic boundary layer for different periods of their lives or at different times of the day (Mees & Jones, 1997;Ligas et al., 2007). Suprabenthos may also be considered as the assemblage composed of small swimming animals, mainly crustaceans, that live directly above the sediment and can migrate on a daily or seasonal basis (Brunel et al., 1978;Munilla & San Vicente, 2005). ...
... Finally, Ligas et al. (2007) argued that seasonal patterns in the suprabenthos and suprabenthic crustacean fluctuations may be related to biological and ecological characteristics rather than environmental factors. Perhaps these biological factors may be the major determinants of the suprabenthic assemblages in Venezuela. ...
The suprabenthos or hyperbenthos is the macrofaunal assemblage of small-sized organisms that interact for some time in the benthic boundary layer. Information about the taxonomic composition and role of suprabenthic species, especially in littoral zones, is scarce and scattered. This work attempts to contribute alleviate this problem. We analyze the temporal and spatial variations of suprabenthic assemblages in the swash-zone from four beaches of the littoral coast of Venezuela. For each beach, two sites were chosen, and special attention was given to water and sediment characteristics. 12 environmental variables were measured: Dissolved oxygen, oxygen saturation percentage, pH, salinity, surface temperature, total, organic and inorganic suspended solids, total organic carbon, organic matter in sediment, grain size of sediment, and amount of dragged material of sample. All faunal samples were taken on a monthly basis during 2011; these were extracted using a manual suprabenthic sledge towed parallel to the shoreline. Samples were sorted and identified to their lowest possible taxonomic level. A total of 24 141 specimens (mean abundance: 26.16±55.35ind./m²) belonging to 21 taxonomic groups were identified. Analysis suggests that seasonality does not explain observed changes either in fauna or environmental variables. It was found that suprabenthic assemblages, total suprabenthos density, richness and environmental variables changed in a dissimilar fashion between months and beaches. The most frequent groups were amphipods and decapods; and at the species/categories level post-larval shrimp (Penaeidae), Grapsidae crab megalopae and Arenaeus cribarius megalopae were common. Dissimilarity between months in each beach was primarily explained by the abundance of amphipods, ctenophores, decapods and mysids. For particular months and selected beaches very high abundances of ctenophores were found. This group dominated the sample even though it is not usually a representative group in suprabenthos. Samples showed low correlations between suprabenthos and environmental variables. A somewhat stronger correlation could be established between water characteristics and dragged material abundance. The studied suprabenthos assemblage was found to have high taxa richness and very dynamic behaviour at spatial and temporal scale. Further analysis suggested that there is no evident pattern of distribution and that causality can not be directly attributed to temporal variation only. Possibly there is an influence of a synergy of environmentals or biological factors, rather than a single variable. The species Americamysis bahia and Americamysis taironana are reported for the first time in Venezuela. This study represents the first ecological research of the suprabenthos in the Caribbean region.
... The suprabenthos or hyperbenthos communities are macrofaunal assemblages of smallsized organisms living in the benthic boundary layer for different periods of their lives or at different times of the day (Mees & Jones, 1997;Ligas et al., 2007). Suprabenthos may also be considered as the assemblage composed of small swimming animals, mainly crustaceans, that live directly above the sediment and can migrate on a daily or seasonal basis (Brunel et al., 1978;Munilla & San Vicente, 2005). ...
... Finally, Ligas et al. (2007) argued that seasonal patterns in the suprabenthos and suprabenthic crustacean fluctuations may be related to biological and ecological characteristics rather than environmental factors. Perhaps these biological factors may be the major determinants of the suprabenthic assemblages in Venezuela. ...
The suprabenthos or hyperbenthos is the macrofaunal assemblage of small-sized organisms that interact for some time in the benthic boundary layer. Information about the taxonomic composition and role of suprabenthic species, especially in littoral zones, is scarce and scattered. This work attempts to contribute alleviate this problem. We analyze the temporal and spatial variations of suprabenthic assemblages in the swash-zone from four beaches of the littoral coast of Venezuela. For each beach, two sites were chosen, and special attention was given to water and sediment characteristics. 12 environmental variables were measured: Dissolved oxygen, oxygen saturation percentage, pH, salinity, surface temperature, total, organic and inorganic suspended solids, total organic carbon, organic matter in sediment, grain size of sediment, and amount of dragged material of sample. All faunal samples were taken on a monthly basis during 2011; these were extracted using a manual suprabenthic sledge towed parallel to the shoreline. Samples were sorted and identified to their lowest possible taxonomic level. A total of 24 141 specimens (mean abundance: 26.16 +/- 55.35 ind./m2) belonging to 21 taxonomic groups were identified. Analysis suggests that seasonality does not explain observed changes either in fauna or environmental variables. It was found that suprabenthic assemblages, total suprabenthos density, richness and environmental variables changed in a dissimilar fashion between months and beaches. The most frequent groups were amphipods and decapods; and at the species/categories level post-larval shrimp (Penaeidae), Grapsidae crab megalopae and Arenaeus cribarius megalopae were common. Dissimilarity between months in each beach was primarily explained by the abundance of amphipods, ctenophores, decapods and mysids. For particular months and selected beaches very high abundances of ctenophores were found. This group dominated the sample even though it is not usually a representative group in suprabenthos. Samples showed low correlations between suprabenthos and environmental variables. A somewhat stronger correlation could be established between water characteristics and dragged material abundance. The studied suprabenthos assemblage was found to have high taxa richness and very dynamic behaviour at spatial and temporal scale. Further analysis suggested that there is no evident pattern of distribution and that causality can not be directly attributed to temporal variation only. Possibly there is an influence of a synergy of environmentals or biological factors, rather than a single variable. The species Americamysis bahia and Americamysis taironana are reported for the first time in Venezuela. This study represents the first ecological research of the suprabenthos in the Caribbean region.
... Suprabenthos or hyperbenthos is the macrofaunal assemblage composed of small-sized organisms (particularly peracarid crustaceans) that live in the benthic boundary layer over different periods of their lives or at different times of the day (Mees & Jones, 1997;Ligas et al., 2007). It has also been defined as the assemblage composed by small swimming animals, mainly crustaceans, which live directly above the sediment and can migrate on a daily or seasonal basis (Brunel et al., 1978;Munilla & San Vicente, 2005). ...
... Thus, the input and output of these organisms which are good swimmers is another contribution to the dynamics of the community. Ligas et al. (2007) suggested that seasonal patterns and fluctuations of hyperbenthic crustaceans should be mainly related to biological and ecological characteristics, such as life cycles, population dynamics and migrations, among others, rather than to environmental factors. Given that we found very little correlation between amphipod density and biomass with environmental parameters, it is likely that these factors may be related to biological parameters. ...
Peracarid crustaceans are a very diverse benthic group and one of the dominant taxa within the suprabenthic community. The Barlovento beaches in Venezuela are characterised by large inputs of organic matter and an important assemblage of amphipods has been observed to thrive in this area. In this paper we describe the species composition of this amphipod assemblage along with their spatial and temporal variation and relationship with some environmental variables on four beaches (Agua Sal, Los Timones, Las Cabañas, Valle Seco). Results showed no significant differences in the amphipod community structure and total density of organisms regardless of the season (rainy and dry). From the 7569 amphipods collected, a total of 20 species were identified within 14 families and 17 genera. The species Apohyale media (Dana, 1953), Metatiron tropakis (J. L. Barnard, 1972) and Nototropis minikoi (A. O. Walker, 1905) were the most abundant species in terms of density, and the last two also in terms of frequency of occurrence. Differences in biomass were not significant at any level (season, beach and their interactions); however, the highest amphipod biomass throughout the year was observed at Valle Seco Beach with peaks in January, August and December coinciding with large accumulations of bryozoans and wood debris. Amphipod density and biomass had low correlation values with the environmental variables; the material caught in the suprabenthos net being the most common variable influencing the community.
... Mysids occur in a huge variety of habitats (algal beds, corals, seagrass meadows, sand, caves; Obrien 1988, Ohtsuka et al. 1995, Wittmann and Ariani 1998, San Vicente and Monniot 2014, and their life styles vary between distinctly hyperbenthic and benthopelagic to different degrees, to clearly pelagic (Clutter 1969, Mauchline 1980, Mees et al. 1993, Macquart-Moulin and Maycas 1995, Roast et al. 1998b, Aguzzi et al. 2007. Hyperbenthic species occupy the benthic boundary layer immediately above the sea bottom and depend on the proximity of the bottom (Mees and Hamerlynck 1992, Mees and Jones 1997, Ligas et al. 2007). Benthopelagic species, in contrast, are only associated with the bottom by day, but display distinct vertical migration up into the water column at night (Wishner 1980, Macquart-Moulin and Maycas 1995, Takahashi and Kawaguchi 1997, Kibirige et al. 2003b. ...
In the highly dynamic environment of an estuary, environmental factors such as salinity,
temperature, light and hydrodynamics as well as biogenic factors such as predator/prey interactions
influence the population dynamics of estuarine species. The aim of my study was to explore the
potential for resource partitioning between four commonly co-existing estuarine mysid species,
Tenagomysis chiltoni, Tenagomysis novae-zealandiae, Tenagomysis macropsis, and Gastrosaccus
australis, by investigating their life histories, seasonalities and distributions within an estuary. Mysid
samples were collected along the shoreline (water depth: 0.5 – 0.6 m) of the Taieri Estuary (South
Island, New Zealand) using a sweep net and in the deeper water (water depth: 4 – 6 m) with a set of
3 drift nets.
A lateral segregation in the estuary was found between the two hyperbenthic species, T. chiltoni and
T. novae-zealandiae, and the two benthopelagic species, G. australis and T. macropsis with
hyperbenthic mysids mainly occurring in the shallow waters along the estuary shoreline and
benthopelagic species in deeper central-channel waters. The life cycle and breeding dynamics of all
four mysid species were similar to those described in the literature for other temperate estuarine
mysid species, although the breeding period in the study estuary was noticeably shorter than in
estuaries of lower latitudes in New Zealand and elsewhere. The observed seasonal migrations and
life-stage specific segregation between adults and juveniles may reduce competition, inter-specific
predation, and cannibalism by allowing different life stages to utilise the same habitats or food
sources, but at different times.
Water temperature seems to play a key role for the timing of the breeding season, abundance, and
reproductive effort, whereas salinity, total suspended solids and phytoplankton biomass (measured
as chlorophyll a) were associated with the distribution of the mysid species. Thus, the spatial
distribution of these four mysid species within the Taieri Estuary reflects the complex linkages and
interactions between favourable temperature and salinity conditions, food availability and
reproduction.
As a consequence of confirming the lateral and longitudinal segregation of species and life history
stages within the estuary, the question arose of how relatively small aquatic organisms, such as
mysids, orient themselves in a large three-dimensional body of moving water. Therefore the role of
turbulence as an orientation aid was investigated in a flume tank experiment, using Gastrosaccus
australis as the test organism. The mysids actively tracked areas of shear, when turbulence was
present, but favoured reduced flow in the absence of turbulence. These different swimming
responses might be an adaptation of G. australis to its pelagic habitat. By moving to reduced flow
areas in an absence of mid-water turbulence, mysids could avoid seaward displacement.
Change in riverine management such as by water abstraction, damming for hydropower plants, or
extreme weather events associated with climate change will impact distribution, densities and
population dynamics of the resident mysid species in estuaries. These changes in abundance or, in
the worst case scenario, even the loss of mysid species could potentially have severe consequences
for estuarine food webs, which may result in decreased food availability and therefore impact the
nursery function of estuaries for commercial fish species.
... Lately, expeditions for investigation of the hyperbenthic fauna have taken place in Arctic and Antarctic areas by using modified RP and Macer-GIROC sledges, respectively (Brandt, 1995; Brandt & Barthel, 1995; Brandt & Schnack, 1999; Brandt & Berge, 2007; San Vicente et al., 1997; 2009). However, surveys conducted on the continental shelf of the western Mediterranean Sea are scarce, e.g. the Gulf of Marseille (Champalbert & Macquart-Moulin, 1970), the Ebro River Delta (Cartes et al., 2007), the northern Adriatic Sea and the northern Sicily coasts (Ligas et al., 2007; Fanelli et al., 2009a;). The Macer-GIROQ sledge was used for most of these studies. ...
... The presence of these species together with several less abundant ones, such as the mysids Leptomysis gracilis, Siriella norvegica, the amphipods Westwoodila rectirostris, Phtisica marina, and the cumaceans Diastylis rugosa, Pseudocuma simile, characterizes the deeper oligotrophic part of the continental shelf. They are also commonly found in other shelf areas of the western Mediterranean Sea, e.g. the Ebro River Delta ( Cartes et al., 2007), the Gulf of Marseille (Macquart-Moulin, 1984, 1991Macquart-Moulin and RiberaMaycas, 1995), the northern Adriatic Sea and the northern Sicily coasts ( Ligas et al., 2007;Fanelli et al., 2009aFanelli et al., , 2011. Though the upper continental slope (stations 3 and 4) of Heraklion Bay is characterized by totally different faunal elements such as the mysid Hypererythrops sp., the amphipod Rhachotropis integricauda and the cumacean Campylaspis sulcata, which are not common in the western basin of the Mediterranean Sea, it is also dominated by species inhabiting the shelf area, such as the mysids E. cf. ...
The community structure of hyperbenthos on continental shelves and upper slopes of oligotrophic areas have been little studied. The present study, located in the eastern Mediterranean (Heraklion Bay, Crete) gives the first description of this using samples collected at depths ranging between 50 and 300 m in two seasonal occasions (March and September 2001) using a modified hyperbenthic sledge (0.5 mm mesh size) specifically designed to resuspend the sediment surface and to sample simultaneously the hyperbenthic macrofauna. The analysis revealed 96 different taxa (Peracarida and Decapoda) with densities ranging from 198 to 2618 ind 100 m(-2) and indicated the presence of a clear zonation of the hyperbenthic communities along a depth gradient as well as different diel and seasonal adaptations to the prevailing environmental conditions of the community structure. Artificial resuspension of the sediment surface revealed that the highest proportion of the hyperbenthic macrofauna collected in this oligotrophic environment (74-100 %) was found to reside at the sediment-water interface (0-0.05 m). This demersal behaviour seems to be a response to high light levels close to the seabed and availability of food sources associated with the sediment surface.
Supporting information 2nd file.
In the 19th century the lophogastrids, mysids and euphausiids were united in the order Schizopoda, mainly based on the biramous thoracopods. With the classification of Calman (1904) the euphausiids were grouped together with the decapods as Eucarida, and the designation Schizopoda became invalid. Until just recently the mysids and lophogastrids were then grouped in the order Mysidacea, also reflected by the previous checklists of the Italian fauna (Froglia et al., 1995; Ariani & Wittmann, 2005). Based on morphological data (Schram, 1984; Richter & Scholz, 2001) and increasing genetic evidence (Meland & Willassen, 2007), a possible monophyly of the formerly acknowledged Mysidacea became increasingly unlikely, and therefore the two groups are now classified separately as the orders Lophogastrida and Mysida. Both orders are treated here in a single contribution exclusively for reasons of
brevity.
The present paper describes the Mysidacea associated with seagrass meadows on sandy bottoms from the southeast Iberian coast (El Campello, Alicante). The mysids were obtained using the hand-net method in different types of habitats: Posidonia oceanica (L.) Delile, 1813 and Cymodocea nodosa (Ucria) Ascherson, 1869 meadows, posidonia meadows edges and sandy bottoms, at deep of 10 and 16 m. Eight species were identified: Siriella clausii, S. armata, Mysidopsis gibbosa, Anchialina agilis, Leptomysis posidoniae, L. buergii, Mesopodopsis slabberi y Paramysis helleri. Abundance varied according to the habitat. A key for the identification of these species is provided.
Using available data from the literature, we compared the production-biomass ratios (P/B) between the suprabenthic (= hyperbenthic) and the benthic (infauna-epifauna) species within the group of the macrofaunal marine crustaceans. This data set consists of 91 P/B estimates (26 for suprabenthos and 65 for infauna-epifauna) for 49 differ- ent species. Suprabenthic crustacean P/B was significantly higher than P/B of benthic crustacean (post-hoc Scheffé test; one-way analysis of covariance, ANCOVA; p
Mysidacea associated with seagrass meadows off the southeast Iberian coast The present paper describes the Mysidacea associated with seagrass meadows on sandy bottoms from the southeast Iberian coast (El Campello, Alicante). The mysids were obtained using the hand-net method in dif- ferent types of habitats: Posidonia oceanica (L.) Delile, 1813 and Cymodocea nodosa (Ucria) Ascherson, 1869 meadows, posidonia meadows edges and sandy bottoms, at deep of 10 and 16 m. Eight species were identified: Siriella clausii, S. armata, Mysidopsis gibbosa, Anchialina agilis, Leptomysis posidoniae, L. buergii, Mesopodopsis slabberi y Paramysis helleri. Abundance varied according to the habitat. A key for the identification of these species is provided.
For four species of Paraleptomysis, revised or new descriptions are given based on type material and partly on additional material from a large distribution range. P. banyulensis (Băcescu) is elevated to species rank, and a new taxon, P. dimorpha sp.n., from equatorial West Africa is described. One may distinguish two biogeographically definable groups: 1) Atlantic and Mediterranean species, P. apiops, P. banyulensis, and P. dimorpha, with one spiniform projection at sympod of antenna; and 2) eastern Indian Ocean and China Sea species, P. xenops and P. sinensis, with two projections at this sympod.
Seven species of gastrosaccini mysids, one species of GaslrosacclIs and six species of Haploslyllls, are reported from the coastal waters of Australia, based on specimens deposited in the Western Australian Museum, Perth. Among them, one HaploMt/llIs species from Western Australia is considered new and described as if. ICl/lIicalldlls sp. novo The new species resembles the Australian congeners, H. qllccl/slal/dcl/sis (Bacescu and Udrescu, 1(82), H. /ldrCSC11I Greenwood cl al., 1991, H. a/lslralicl/sis Wooldridge cl al., 1992, and if. dispar Panampunnayil, 1997, but differs from all the related species by having the following characters: the telson is relatively more slender, length 3 times basal width, laterally armed with more than 10 spines, including the terminal spine, with the subterminal spine smaller than and placed close to the terminal spine; the exopod of the male third pleopod has the terminal segment consistently longer than the penultimate segment. A key to all known Haploslyllls species is presented.
Mucilage events, i.e. the accumulation of a gelatinous material at and below the water surface during summer months, have been known to occur at irregular intervals in the Northern Adriatic Sea for over 200 years, but events of the severity of those of 1872 and 1905 were less noted later in this century. The phenomenon reappeared in 1988 and in the years that followed. In 1991 it was also noted in the Tyrrhenian Sea. Our studies cover the events of 1988–1991 in the Northwest Adriatic and some aspects of the Tyrrhenian Sea. The results presented in this paper provide additional insight into the problem. In general, it can be stated that while we have a fair understanding of the phenomenological and dynamic aspects, and of the environmental consequences of the events, we know little about the causal factors which trigger and maintain the process.
Enlarged versions of the MACER sled-mounted suprabenthic sampler were tested, improved, calibrated and used extensively (598 tows) at depths of 10—384 m since 1968 in the Gulf and Estuary of the St. Lawrence. Two half-metre zooplankton nets are mounted at 28—64 and 106—142 cm from the sea-bed, on a steel chassis and toboggan plate. Each has a flow-meter and 3 horizontal shutters which open via a lever upon contact with the sea floor. They close automatically, through springs and water pressure, whenever the sled leaves the bottom, ensuring uncontaminated suprabenthic samples. Although heavy (228 kg), the device is sturdy, used like a beam trawl, reliable, and collects very little sediment. It has been used to study micro-stratification above bottom. Data on filtered water volumes, special problems encountered and future improvements are discussed.
A first estimate of secondary production in populations of deep-water suprabenthic peracarids of the Catalan Sea slope (northwestern Mediterranean) was attempted. Estimates are based both on the size-frequency Hynes-Hamilton method and on two empiric models. Our data set was based on four oceanographic cruises carried out in 1991 and 1992 between 391 and 1255 m depth, covering the four annual seasons (April 1991, December 1991, March 1992, and July 1992). Production oscillated, depending of each species, between 0.129 mg DW/m2/year for the Cumacea Leucon longirostris and 9.002 mg DW/m2/year for the mysid Boreomysis arctica. P/B ratios ranged between 1.56 for L. longirostris and 12.64 for the Amphipoda Rhachotropis glabra. The extreme results cited were always obtained with the Hynes-Hamilton method. Comparing the two empiric models used, Brey’s (1990) equation values were always lower than the results obtained with the Morin and Bourassa (1992) model, both for production and P/B ratios. Our production values for deep-sea peracarids were always lower ( 4–5 orders of magnitude lower in the case of Amphipoda) than available data for marine littoral and shallow-water peracarids. However, P/B ratios obtained from our suprabenthic deep-water peracarids were within the same range as that cited for coastal and neritic species. Also, and summarising the available data, suprabenthos crustaceans showed higher P/B ratios than infauna, whereas P/B for our suprabenthic species were within the range cited for mesopelagic euphausiids.
The specific composition of peracarid Crustacea (suprabenthos) caught at bathyal depths (473-603 m) in the Ionian Sea (eastern Mediterranean) is presented. A total of 66 species were identified (11 mysids, 16 cumaceans, 25 gammaridean amphipods, 13 isopods, and 1 tanaid). At least 19 of the peracarids cited are new records for the eastern Mediterranean: Arrhis mediterraneus, Bathymedon longirostris, Oediceroides pilosus, Pardaliscoides stebbingi, and Syrrhoe affinis (Amphipoda); Dactylamblyops sp., Euchaetomeropsis merolepis, Pseudomma nanum, Calyptomma puritani, and Erythrops neapolitanus (Mysidacea); Belonectes parvus, Disconectes cf. furcatus, Disconectes cf. phallangium, Ilyarachna longicornis, and Eurydice cf. grimaldii (Isopoda); Campylaspis
horridoides, Cumella gracillima, Cumellopsis puritani, and Eudorella truncatula (Cumacea). Mysids, particularly Boreomysis arctica, were the dominant species of this bathyal community. Qualitative comparison with the deep suprabenthic fauna from the western Mediterranean showed that a similar species composition and diversity is found in both areas. However, a number of dominant species (e.g., Rhachotropis caeca and Bathymedon longirostris) are distributed shallower in the Ionian Sea than they are in the Catalan Sea (western basin) where they are dominant on the lower slope (1200-1350 m). Se presenta la composición específica de los crustáceos peracáridos (suprabentos) capturados en profundidades batiales (473-603 m) del Mar Jónico (Mediterráneo oriental). Un total de 66 especies han sido identificadas (11 misidáceos, 16 cumáceos, 25 anfípodos gammarideos, 13 isópodos y 1 tanaidáceo). Por lo menos 19 de los peracáridos capturados son nuevas citas para el Mediterráneo oriental: Arrhis mediterraneus, Bathymedon longirostris, Oediceroides pilosus, Pardaliscoides stebbingi, y Syrrhoe affinis(Amphipoda); Dactylamblyops sp., Euchaetomeropsis merolepis, Pseudomma nanum, Calyptomma puritani, y Erythrops neapolitanus (Mysidacea); Belonectes
parvus, Disconectes cf. furcatus, Disconectes cf. phallangium, Ilyarachna longicornis, y Eurydice grimaldii (Isopoda); Campylaspis horridoides, Cumella gracillima, Cumellopsis puritani, y Eudorella truncatula (Cumacea). Los misidáceos, especialmente Boreomysis arctica, han sido las especies dominantes en esta comunidad batial. La comparación cualitativa con la fauna suprabentónica de profundidad del Mediterráneo occidental mostró que la composición de las especies y la diversidad es similar en ambas zonas. Sin embargo, algunas especies dominantes (p.e., Rhachotropis caeca y Bathymedon longirostris) se distribuyen a menor profundidad en el Mar Jónico que en el Mar Catalán ( cuenca occidental), donde estas especies se encuentran en el talud inferior (1200-1350 m).
In summer 1997, gelatinous aggregates appeared in the Adriatic Sea, covering large areas of the northern basin. This study deals with the comparison between the biochemical composition of the sedimentary organic matter in summer, 1996 (when no aggregates appeared), and in summer, 1997 (during the appearance of aggregates). the biochemical composition of organic matter in surface sediments (determined in terms of proteins, carbohydrates, lipids, phytopigments and nucleic acids) has been investigated in two areas along the coast of the NW-Adriatic Sea in order to characterize benthic processes during aggregate deposition on the sea floor. During mucilage accumulation, a significant increase of biochemical compounds was observed, and chlorophyll-a and carbohydrate concentrations doubled their concentrations. in contrast, protein concentrations decreased, so that overall biopolymeric carbon content (expressed as the sum of lipid, protein and carbohydrate carbon equivalents) did not display significant differences between sampling periods (1579.3 in June, 1996 1678.8 μgCg and June, 1997). the protein to carbohydrate ratio decreased from 4.9 in June, 1996 to 1.8 in June, 1997. Mucilage production in June, 1997, modified significantly the biochemical composition of the sedimentary OM, thus affecting the potential availability of OM to benthic consumers. We hypothesise that the production of highly refractory composition of the sedimentary OM during mucilage accumulation might have an important biogeochemical implications.
Stomach contents of 144 specimens of Oblada melanura were analyzed for diet composition. All specimens belonged to the 1-year age group. Material was collected from the localities of Kornati Archipelago and Murter Island in the eastern central Adriatic during 1992–1993. Copepod crustaceans were the main food, while Cladocera crustaceans were the second most important. Feeding intensity was very high as indicated by high stomach fullness index and low vacuity index.
Reproduction in peracarid crustaceans is characterized by direct development with the young carried by the female in a ventral brood pouch made from overlapping oostegites. The major exception occurs in thermosbaenaceans where the young develop under a posterior extension of the carapace. Sexual reproduction is the norm, as is standard genetic development of males and females, but intersexes, males with unusual chromosome numbers and hermaphrodites occur in some species.General anatomy of the female reproductive tract is similar for all orders, differing only in the specific details. Asellote isopods develop a unique spermathecal duct for sperm storage. The male reproductive system is much more variable. In some orders it consists of paired tubes, and in others it is unpaired; sperm may be stored in the posterior region of the testes or in vas deferens; and the external genitalia may be located on the coxae or the sternites, with or without penes or other sperm transfer appendages.Sperm morphology has been considered a unifying trait for the Peracarida but, in fact, there are some significant differences among the orders. Peracaridan sperm are aflagellate. Most consist of a head piece and a rigid, non-motile, fibrillar tail of varying design by which the sperm are bundled in spermatophores. Tanaid sperm are round and tailless, and spermatophores are absent. Oögenesis follows a common pattern in those peracarids that have been studied. A period of previtellogenic growth is followed by slow primary vitellogenesis with endogenous yolk synthesis Prior to molting and fertilization, rapid secondary vitellogenesis, utilizing exogenous yolk synthesis, occurs.Life cycles in the more diverse peracaridan orders can be compared. Temperate species often have long overwintering generations interspersed with several shorter summer generations. Polar and deep-sea pericaridans have much longer generations whereas tropical species may produce broods year-round in rapid succession. Mating usually occurs when the mature oöstegites appear, with copulation occurring shortly after the female molts. Precopulatory pairing and mate guarding by males using specially modified appendages is common, but some males cruise from one female to another. Sperm is generally deposited into the marsupium where fertilization occurs, but some isopods store sperm for later use.Development follows the general crustacean pattern of superficial cleavage, with the details of organ and appendage formation varying from order to order. Some special brood pouch structures exist, primarily in isopods, and in some tube-dwelling tanaids the young develop in the female's tube rather than in the marsupium. Peracarids generally hatch in the brood pouch as fully developed juveniles or as mancas (without the last pair of thoracic legs).With a few exceptions, brood size is a function of female marsupial volume. The trade-off between egg size and egg number varies with both habitat and, in some cases, with season. Since egg size affects incubation time, these complex interrelationships and the adaptive value of specific reproductive strategies are still unresolved.
The life-histories and the secondary production of four dominant peracarid crustaceans (the mysids Boreomysis arctica and Parapseudomma calloplura, the amphipod Rhachotropis caeca, and the isopod Ilyarachna longicornis) in bathyal depths of the Bay of Biscay (NE Atlantic; between 383 and 420 m) and the Catalan Sea (Northwestern Mediterranean; between 389 and 1355 m) were established. Both the Atlantic and the Mediterranean populations of the major part of the target-species had two generations/year with mean cohort-production intervals (CPI) ranging from 5.5 mo for Ilyarachna longicornis to 6.3 mo for Parapseudomma calloplura. The Hynes method showed secondary production to vary in the Bay of Biscay between 0.113 mg DW m−2 yr−1 for I. longirostris and 3.069 mg DW m−2 yr−1 for P. calloplura, with P/B ratios between 4.57 (I. longirostris) and 7.93 (Boreomysis arctica). In the Catalan Sea, production varied between 0.286 mg DW m−2 yr−1 for I. longirostris and 1.096 mg DW m−2 yr−1 for P. calloplura, with P/B between 5.72 (I. longirostris) and 6.66 (P. calloplura). Application of two different empiric models to the whole peracarid assemblage gave similar levels of secondary production in both study areas (between 29.26 and 32.14 mgDWm−2 yr−1 in the Bay of Biscay; between 26.23 and 26.54 mg DW m−2 yr−1 in the Catalan Sea). From the analysis of gut contents of 22 species the dominant species in each study area were assigned to two basic trophic levels, detritus feeders and predators. Also, cumulative curves of dominance showed high diversity (low dominance) for peracarid assemblages distributed at mid-bathyal depths (524–693 m) both in the Bay of Biscay off Arcachon and in the Catalan Sea off Barcelona. We also discuss and compare, both within and between areas, how environmental features may explain the observed diversity patterns, the trophic structure, and the production results obtained for the suprabenthos assemblages.
In June 2000 and July 2002, two mucous aggregation events of large proportion occurred in the Adriatic Sea. In order to assess the possible effects that the events had on the macrofauna, we studied macro-zoobenthic assemblages and mussel culture (Mytilus galloprovincialis). Structural parameters of macro-zoobenthos and growth parameters of mussels were recorded. The study area was a mussel farm located 5 nautical miles off Porto Caleri (Rovigo, Italy) in the Northern Adriatic Sea. Between May 2000 and August 2002, two sites were sampled in this area and univariate and multivariate techniques were used to describe the macrobenthic community. Two-way ANOVA showed that mean values of species number, density (individuals m(-2)) and Shannon-Wiener's diversity were significantly influenced (p<0.01) by site and period of sampling and by the interactions of these factors. The Pielou's J averages were significantly influenced only by period (p<0.01). Application of Tuckey's HSD test (p<0.05) to factors detected to be significant by ANOVA did not show significant differences between samples collected after the mucous aggregation events and the other periods. Cluster analysis and MDS ordination did not allow a clear distinction between the samples. Concerning mussels, one-way ANOVA showed that mean values of the shell length and the condition index (dry weight/shell weight) were significantly influenced (p<0.001) by the months. The mean values both for shell length and condition index were higher in 2001. The shell length trend revealed a slowing down of growth in June-July 2000 and July-August 2002, and the condition index trend showed a significant fall in samples of June 2000 and July 2002. The growth of M. galloprovincialis might be influenced negatively by mucous aggregates, whereas the soft-bottom macro-zoobenthos seems not to be directly affected by the event.
Description de Haplostylus bacescui n. sp. et révision de la nomenclature des Haplostylus et Gastrosaccus méditerranéens
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appareil amélioré pour l'échantillonage quantitatif étagé de la petite faune nageuse au voisinage du fond
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The British Mysidacea: 1-460
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