Showing papers in "Journal of the Marine Biological Association of the United Kingdom in 2009"
TL;DR: There is broad agreement that certain species and populations are likely to be especially vulnerable to climate related changes, including those with a limited habitat range, or those for which sea ice provides an important habitat for the cetacean population and/or that of their prey.
Abstract: At least a quarter of the world's cetaceans were recently confirmed as endangered and the situation may be worse as the status of many others remains unclear. Climate change is affecting the oceans and a number of studies have recently highlighted its potential impact on cetacean species - for example, there are important linkages between sea ice and krill, the primary prey for baleen whales in Antarctica. This paper provides a synthesis of new information available on this theme and considers its implications for the future conservation and management of cetacean populations and species. The more mobile (or otherwise adaptable) cetaceans may be able to respond to climate related changes, although the extent of this adaptability is largely unknown. However, there is broad agreement that certain species and populations are likely to be especially vulnerable to climate related changes, including those with a limited habitat range, or those for which sea ice provides an important habitat for the cetacean population and/or that of their prey. International conservation bodies, such as the Convention for Migratory Species and the International Whaling Commission, are striving to address these issues. The challenges presented by climate change require an innovative, large scale, long term and multinational response from scientists, conservation managers and decision makers. This response that should encompass a precautionary approach, including addressing the detrimental effects of other factors negatively impacting populations and species.
89 citations
TL;DR: In the Mediterranean Sea, changes in bio-chemical and physical seawater properties resulting from global warming are likely to alter marine biodiversity and productivity, trigger trophic web mismatches and encourage diseases, toxic algal bloom and propagation of thermophilic species as mentioned in this paper.
Abstract: The combustion of fossil fuels and the resultant impacts on climate may now represent one of the largest environmental threats. In the Mediterranean Sea, changes in bio-chemical and physical seawater properties resulting from global warming are likely to alter marine biodiversity and productivity, trigger trophic web mismatches and encourage diseases, toxic algal bloom and propagation of thermophilic species. This review highlights the current and potential threats of climate change to the Mediterranean marine ecosystems, including cetaceans, and stresses the emergent necessity for more integrated regulations and policies for the protection of marine biodiversity. For instance, in the Mediterranean Sea, the distribution and abundance of the small euphausid species Meganyctiphanes norvegica is correlated with specific hydrobiological parameters including seawater temperature, salinity and current patterns. Situated at the northern limit of its ecological tolerance, this species, which constitutes the only known food supply of the fin whales (Balaenoptera physalus) in this region, might be affected by climate change-induced alteration of ocean circulation.
75 citations
TL;DR: Results suggest that the PFES system is more effective than the conventional slide method for periphytic ciliate colonization with high species diversity, evenness and sensitive temporal dynamics mainly due to the reduction of disturbances from tidal current and circulation in marine ecosystems.
Abstract: Structural parameters of periphytic ciliate communities on a modified substrate were studied in Korean coastal waters during the period August-November 2007. In order to reduce the strong disturbances from tidal current and circulation in marine ecosystems, a modified slide method, named the polyurethane foam enveloped slide (PFES) system, was used to host ciliate communities. A total of 37 ciliate species, about half of which belong to the orders Hypotrichida and Cyrtophorida, were identified using living observation and silver impregnation method with this system. The sessile ciliates belonged to the orders Peritrichida and Suctorida, while the motile forms were represented primarily by the species of the orders Hypotrichida, Cyrtophorida and Pleurostomatida. The species diversity and evenness were significantly higher in the PFES system than those on the conventional slides (paired t-test: t = 2.384, 2.415; P < 0.05). Multivariate analysis revealed that the ciliate communities from both sampling systems had similar species composition, but represented significant differences in species distribution and temporal dynamics mainly due to the most dominant peritrich Zoothaminium duplicatum, which overly colonized the conventional slides. Results suggest that the PFES system is more effective than the conventional slide method for periphytic ciliate colonization with high species diversity, evenness and sensitive temporal dynamics mainly due to the reduction of disturbances from tidal current and circulation in marine ecosystems.
70 citations
TL;DR: Results obtained in this work suggest that, at this invasion stage, there is no evidence of interspecific competition, Nevertheless, since density and diversity of the fauna associated with the holdfast is different, the authors expect community changes if the U. pinnatifida invasion continues to expand.
Abstract: Biological invasions can alter the biodiversity of native communities generating an ecological impact that in many cases is irreversible. In 2001 , Undaria pinnatifida invaded Macrocystis pyrifera kelp in Cracker Bay (42°56'S, 64°27'W; Northern Patagonia, Argentina). The possible impact of that invasion was evaluated in March 2004 with a study of population and morphological parameters of both kelp species and their associated holdfast biodiversity. Three nearby areas of spatial distribution of the kelps were differentiated, one dominated by M. pyrifera (M), an intermediate area characterized by M. pyrifera and U. pinnatifida (M + U), and another dominated by U. pinnatifida (U). In each area, sporophytes in nine quadrats of 1 m 2 were collected. The density and biomass m -2 , the height of the sporophytes and the size of the holdfast of M. pyrifera did not diminish in the presence of U. pinnatifida. The richness, abundance and diversity of the flora associated with the holdfast of both kelps were similar, whereas these parameters were higher in the case of the fauna associated to M. pyrifera than U. pinnatifida Results obtained in this work suggest that, at this invasion stage, there is no evidence of inter-specific competition. Nevertheless, since density and diversity of the fauna associated with the holdfast is different, we expect community changes if the U. pinnatifida invasion continues to expand.
64 citations
TL;DR: The digenean fauna of one of the dominant intertidal hosts, the common cockle Cerastoderma edule, in terms of biomass, off north-eastern Atlantic shores is described and an identification key is prepared and an up-date of the large-scale distributional patterns are provided.
Abstract: We describe the digenean fauna of one of the dominant intertidal hosts, the common cockle Cerastoderma edule, in terms of biomass, off north-eastern Atlantic shores. Using published and unpublished literature we have prepared an identification key and provide an up-date of the large-scale distributional patterns of digenean species of the common cockle. At least sixteen digenean species, belonging to seven families, use cockles as intermediate host. Among these species two utilize cockles as first intermediate host only, whereas two species utilize cockles as both first and second intermediate host. The remaining eleven species have cockles as their second intermediate host. Water birds and fish are the definitive hosts to twelve and four species, respectively.Cockles are infected with digeneans along the latitudinal gradient from southern Morocco to the western region of the Barents Sea often with high infection levels. Whereas some of these digenean species occur along most of the latitudinal gradient others show a more restricted northern or southern distribution mostly caused by an underlying latitudinal gradient of host species.Knowledge of digenean species and their large-scale distribution pattern may serve as a baseline for future studies dealing with the effects of climate change on parasite–host systems. For such studies the cockle and its digenean community could be an ideal model system.
64 citations
TL;DR: In this paper, the authors describe the peracaridean fauna associated to the algae Corallina elongata from the Strait of Gibraltar, and explore possible biodiversity and biogeographical patterns of variation along the north-south and Atlantic-Mediterranean axes across the Strait.
Abstract: The objectives of this study were to describe the peracaridean fauna associated to the algae Corallina elongata from the Strait of Gibraltar, and explore possible biodiversity and biogeographical patterns of variation along the north–south and Atlantic–Mediterranean axes across the Strait of Gibraltar. Twenty-five stations were selected along the north and south coasts of the Strait to cover the broadest possible range of human pressure and environmental conditions, including both natural rocky shores and artificial breakwaters. The alga Corallina elongata was selected as substrate, and the peracaridean crustaceans were identified to species level and classified in geographical distribution groups. Univariate and multivariate analyses were conducted to explore and confirm patterns of variation. Forty peracarid species were collected, most of them with an Atlantic–Mediterranean distribution (67%) with only the gammarid Parhyale eburnea, being an endemic Mediterranean species. The most common species collected during the present study were the gammarids Hyale stebbingi, Jassa marmorata, Stenothoe monoculoides and Ampithoe spp., the caprellids Caprella grandimana and C. penantis, the isopod Ischyromene lacazei and the tanaid Tanais dulongi. The number of species per station and the diversity index were significantly higher in the stations located along the north side of the Strait of Gibraltar. However, the two-way ANOVA discarded differences between north and south due to the type of substrate (natural versus artificial) and degree of human pressure. Based on peracaridean assemblages, the Strait of Gibraltar behaves as a whole and homogeneous region, with a very similar faunal composition in all stations and there is not a clear gradient of species substitution from the Mediterranean to the Atlantic stations. Provided that we selected the same substrate in all stations, and that statistical analyses revealed that differences between north and south stations were not due to environmental factors such as anthropogenic stress or type of substrate, we should look to historical biogeographical reasons to explain the higher diversity in the north side of the Strait of Gibraltar.
60 citations
TL;DR: The correspondence analysis showed strong relationships between high salinity range and the abundance of Brevoortia aurea, Cynoscion guatucupa and Pomatomus saltatrix, and high temperatures and high abundance of Odontesthes argentinensis and Oligosarcus jenynsii were corresponded to low temperatures.
Abstract: Mar Chiquita, an irregularly shaped brackish-water coastal lagoon, is located in the Buenos Aires province of Argentina and considered since 1996 by the Coordination Council of the Man and Biosphere Program of UNESCO as a World Reserve of Biosphere. The present paper aims to study both the spatial and temporal variation of fish composition in this coastal lagoon and the influence of some environmental variables on the relative abundance of the main fish species. Monthly sampling surveys over a two-year period in three different areas were conducted, using a beach-seine net and three monofilament-gill nets with different mesh size. Twenty-eight species belonging to four bio-ecological categories were identified, five of them are new records for Mar Chiquita fish community. The correspondence analysis showed strong relationships between high salinity range and the abundance of Brevoortia aurea, Cynoscion guatucupa and Pomatomus saltatrix. Conversely, low salinity range corresponded to high abundance of Mugil platanus and Odontesthes argentinensis. High temperatures were corresponded with abundance of Micropogonias furnieri and Brevoortia aurea. In contrast, high abundance of both Odontesthes argentinensis and Oligosarcus jenynsii were corresponded to low temperatures. Brevoortia aurea, Mugil platanus and Odontesthes argentinensis were the most abundant species, representing more than 80% of the total capture. The group of estuarine-nondependent-marine fish presented the highest species richness. Estuarine-dependent-marine species presented for both juveniles and adults specimens the highest abundance values.
55 citations
TL;DR: Most of the prey species identified are not of commercial interest but one of the sperm whales contained a fishing hook among the stomach contents, with big plastic items being taken by deep diving teuthophagous whales.
Abstract: Stomach contents were analysed from 23 cetaceans, including individuals of 12 species from the families Delphinidae, Physeteridae, Kogiidae and Ziphiidae, stranded between 199 6 and 2006 in the Canary Islands. Cephalopod mandibles (beaks) were found in 21 stomachs and fish remains (otoliths and jaw bones) appeared in 4 stomachs. Two stomachs contained only eye lenses. Cephalopods eaten by dolphins were mainly from the families Ommastrephidae, Sepiidae and Enoploteuthidae, whereas whales had mainly taken specimens of the oceanic squid families Histiotheutidae and Cranchiidae. Fish remains included a pelagic species (i.e. garfish, Belone belone) in dolphin stomachs and bathypelagic (i.e. black scabbard fish, Aphanopus carbo, lantern fish, Lampadena luminosa) and demersal species (Lophius sp.) in a pygmy sperm whale (Kogia breviceps) stomach. Most of the prey species identified are not of commercial interest but one of the sperm whales (Physeter macrocephalus) contained a fishing hook among the stomach contents. Five ( 22 %) of the cetaceans examined had also plastic debris in their stomachs, with big plastic items being taken by deep diving teuthophagous whales.
53 citations
TL;DR: In this article, the authors investigated the patterns of habitat use with respect to depth for 181 individuals of different age, size, gender and reproductive condition off Rio Grande do Sul, southern Brazil.
Abstract: The patterns of habitat use by the franciscana dolphins (Pontoporia blainvillei) along its distribution are poorly known. This study investigates the patterns of habitat use with respect to depth for 181 individuals of different age, size, gender and reproductive condition off Rio Grande do Sul, southern Brazil. The results reveal that franciscanas are very homogeneously distributed according to depth. Individuals from all lengths utilize nearly the entire range of depths of the surveyed area. Larger or older animals do not use deeper waters than younger animals, indicating that body size and age are not limiting factors for franciscanas that occupy deeper or offshore waters. Gestation seems to not cause a change in the distribution of females. Although the sex-ratio of the overall data did not vary from 1:1 in different depth intervals, a small-scale comparison between the northern and southern coast demonstrated the existence of some kind of sexual segregation. Franciscana by-catch in Rio Grande do Sul is not sustainable and it is agreed that management procedures are needed. Nevertheless, the available data on species distribution do not allow the designing of a protected area in order to minimize the by-catches of a particular sex/reproductive class.
52 citations
TL;DR: All known records from peer-reviewed and broader public literature of the jellyfish R. octopus and R. pulmo are reviewed across western Europe to reveal distinct hotspots where regular Rhizostoma spp.
Abstract: Jellyfish (Cnidaria: Scyphozoa) are increasingly thought to play a number of important ecosystem roles, but often fundamental knowledge of their distribution, seasonality and inter-annual variability is lacking. Bloom forming species, due to their high densities, can have particularly intense trophic and socio-economic impacts. In northern Europe it is known that one particularly large (up to 30 kg wet weight) bloom forming jellyfish is Rhizostoma spp. Given the potential importance, we set out to review all known records from peer-reviewed and broader public literature of the jellyfish R. octopus (Linnaeus) and R. pulmo (Macri) (Scyphozoa: Rhizostomae) across western Europe. These data revealed distinct hotspots where regular Rhizostoma spp. aggregations appeared to form, with other sites characterized by occasional abundances and a widespread distribution of infrequent observations. Surveys of known R. octopus hotspots around the Irish Sea also revealed marked inter-annual variation with particularly high abundances forming during 2003. The location of such consistent aggregations and inter-annual variances are discussed in relation to physical, climatic and dietary variations.
49 citations
TL;DR: In this article, the authors investigated the nursery areas of European sea bass (Dicentrarchus labrax, L.) from spring 2005 to summer 2006 in areas along the French Mediterranean coast of the Gulf of Lion.
Abstract: Nursery areas of European sea bass (Dicentrarchus labrax, L.) were investigated from spring 2005 to summer 2006 in areas along the French Mediterranean coast of the Gulf of Lion. Nurseries were identified by the presence of settling individuals of sea bass and young juveniles. These nurseries represent different types of sheltered shallow habitats, both natural such as coastal lagoons, estuaries, and artificial such as marinas. Settlement occurred from April to June during both years. The number of settling individuals varied between sites from just a few individuals to several thousand. In one given site, settlement also varied between 2005 and 2006. The size distribution of sampled individuals revealed that several pulses arrived in each nursery. At this stage, sea bass already exhibited a strong orientation capacity but a limited swimming ability. The magnitude of sea bass settlement in marinas requires better environmental management of such artificial areas.
TL;DR: This study is the first attempt to monitor dolphin–fisheries interactions and assess depredation rates in Italy, providing information on the areas where future investigation should be concentrated.
Abstract: Conflict between dolphins and fisheries is an important management issue in many parts of the world. In 2002, we examined the extent of depredation in the Italian small scale fishery by means of in situ interviews. Overall, 245 landing sites were investigated, representing 11.09% of the whole Italian artisanal fleet. The association between the commonly used artisanal fishing gear and the interacting fauna was investigated by means of correspondence analysis. Set gillnet and trammel nets were the types of the fishing gear most vulnerable to dolphin depredation; the interaction with these gear amounted to 66.4% while fish damage was reported in 72.2% of the cases. A regional ranking of the interactions in terms of both fishing gear alteration and fish damage, shows that the problem is most pressing in the Friuli, Campania, Sardinia and Apulia regions. This study is the first attempt to monitor dolphin–fisheries interactions and assess depredation rates in Italy, providing information on the areas where future investigation should be concentrated.
TL;DR: The ecology of the indigenous species resulted similar to what is known for the more studied western Mediterranean, with some exceptions, and the total of hydroid species known from the Levant Sea rises to 70, indicating the need for future investigation in this sector of the Mediterranean Sea.
Abstract: Despite the hydroid fauna of the Mediterranean Sea being considered one of the best known in the world, the eastern basin of the Mediterranean Sea remains nearly unexplored. This paper reports on 38 species collected along the Levant Sea coast (mainly Lebanon), of which three are new records for the Mediterranean and nine for the Levant Sea. Six alien species, i.e. Eudendrium carneum, Sertularia marginata, Sertularia techocarpa, Macrorhynchia philippina, Diphasia digitalis and Dynamena quadridentata, are described in detail and illustrated on the basis of Levant Sea material. The last four species are considered as immigrants from the Red Sea. The synonymy of Sertularia stechowi, described from Japan, with S. techocarpa is established. Taken as a whole, the collection comprised a majority of circum-(sub)tropical species, and a reduced proportion of Atlantic–Mediterranean elements and Mediterranean endemics. The ecology (seasonality, depth distribution and habitat preference) of the indigenous species resulted similar to what is known for the more studied western Mediterranean, with some exceptions. Adding the present species inventory to the scanty published information, the total of hydroid species known from the Levant Sea rises to 70, indicating the need for future investigation in this sector of the Mediterranean Sea.
TL;DR: In this paper, the first bottleneck test for the Pacific and Atlantic populations of A. australis based on the analysis of seven microsatellite loci was performed, and moderate support for deviation from neutrality-equilibrium for Pacific population of fur seals and none for the Atlantic population.
Abstract: The South American fur seal, Arctocephalus australis, was one of the earliest otariid seals to be exploited by humans: at least 6000 years ago on the Atlantic coast and 4000 on the Pacific coast of South America. More than 750,000 fur seals were killed in Uruguay until 1991. However, a climatological phenomenon—the severe 1997–1998 El Nino Southern Oscillation (ENSO)—was responsible for the decline of 72% of the Peruvian fur seal population due to starvation as a consequence of warming of sea-surface temperatures and primary productivity reduction. Currently, there is no precise information on global population size or on the species' conservation status. The present study includes the first bottleneck test for the Pacific and Atlantic populations of A. australis based on the analysis of seven microsatellite loci. Genetic bottleneck compromises the evolutionary potential of a population to respond to environmental changes. The perspective becomes even more alarming due to current global warming models that predict stronger and more frequent ENSO events in the future. Our analysis found moderate support for deviation from neutrality–equilibrium for the Pacific population of fur seals and none for the Atlantic population. This difference among population reflects different demographic histories, and is consistent with a greater reduction in population size in the Pacific. Such an event could be a result of the synergic effects of recurrent ENSO events and the anthropogenic impact (sealing and prey overfishing) on this population.
TL;DR: In the study area, Sotalia guianensis, P. macrocephalus and Steno bredanensis were the most abundant cetacean species, whereas Lagenodelphis hosei, Pseudorca crassidens, Orcinus orca, Kogia sima, Mesoplodon europaeus and Balaenoptera bonaerensis are probably rare in the area.
Abstract: This study reviews and updates information on cetacean strandings in the state of Ceara, Brazil (02°30′S 41°15′W– 04°30′S 36°45′W), comprising 573 km of coastline. In the years 1992–2005, there were 252 cetacean stranding events, representing 19 species: three species of Balaenopteridae, three Physeteridae, two Kogiidae, two Ziphiidae and 11 Delphinidae. Three species comprised the majority (78.9%) of stranding events: estuarine dolphin, Sotalia guianensis (61.9%); sperm whale, Physeter macrocephalus (10.3%); and rough-toothed dolphin, Steno bredanensis (6.7%). There was an increasing trend in the number of cases reported in the first five years with a highest frequency achieved in 1996. Stranding events occurred throughout the year, with the lowest frequency occurring in the autumn (March–May). Approximately 4% of the events were attributed to natural causes while 24.6% were human-related, mainly incidental captures. Meat removal for human consumption or bait was recorded in 6.7% of events. In the study area, Sotalia guianensis, P. macrocephalus and Steno bredanensis were the most abundant cetacean species, whereas Lagenodelphis hosei, Pseudorca crassidens, Orcinus orca, Kogia sima, Mesoplodon europaeus, Balaenoptera acutorostrata and Balaenoptera bonaerensis are probably rare in the area.
TL;DR: The analysis connected the shifts in primary production with hemispheric and regional scale climate variations, and supports the hypothesis that atmospheric variability can trigger the ecosystem changes.
Abstract: Interannual variability of the primary production in the middle Adriatic Sea for the period 1961-2002 was examined and correlated to the various atmospheric and oceanographic parameters. The Locally-weighted scatter plot smoothing (LOWESS) method (Cleveland, 1979) and Sequential algorithm for regime shift detection (SARS, Rodinov, 2004) were applied to the primary production mean annual and spring-summer values, revealing the three periods with significantly different mean productivity rate: 1961-1979, 1980-1996 and 1997-2002. Moreover, the period from 1980 to 1996, with the highest primary production, consists of the two distinguished regimes: periods of increasing (1980-1986) and decreasing (1987-1996) primary production. Whereas in the first period the ecosystem was under the influence of warmer and nutrient richer Levantine Intermediate Water (LIW) intrusions into the Adriatic, in the second period, which started with cold winter 1987, the Eastern Mediterranean Transient (EMT) occurred in the Mediterranean. The new circulation regime prevented the LIW intrusions in the Adriatic, causing its reduced productivity. Weak ventilation in the Adriatic was evidenced in the lower than normal sea temperature and oxygen concentrations bellow the thermocline depth. Analysed atmospheric data: air temperature, precipitation, evaporation, air-sea fluxes and the North Atlantic Oscillation (NAO) index showed similar fluctuation pattern as oceanographic data. Changed regime in the ecosystem, observed around 1980s till the end of 1996 can be also associated to the lower than normal precipitation rate, which is connected with more clear days and higher solar radiation input in the sea. Our analysis connected the shifts in primary production with changes in the climate system via changes in the atmosphere and confirmed the hypothesis that atmospheric variability can trigger the ecosystem changes.
TL;DR: The daily presence of spinner dolphins, Stenella longirostris, inside a small reef offshore the Red Sea coast of southern Egypt was monitored from January 2004 to January 2006.
Abstract: The daily presence of spinner dolphins, Stenella longirostris, inside a small reef offshore the Red Sea coast of southern Egypt was monitored from January 2004 to January 2006. Observations indicated marked seasonal and daily variations in the use of the reef as a resting and socializing area by the dolphins, consistent during the two years of monitoring. Overall, the mean number of dolphins present in the reef at any day was 39.2 (SD = 39.34, range 0-210), with the lowest presence in February to April and the highest in June. Similar to other populations of this species in other oceans, dolphins entered the reef between daybreak and mid-morning, and started exiting during the afternoon hours. Although calves were seen in all seasons, a sharp peak was observed in June. Monitoring data provided indications relevant to governmental management efforts, which were implemented in 2004 to ensure that the dolphins could continue using the reef for their resting needs while a sustainable, respectful tourist activity is allowed in a designated zone of the reef adjacent to the dolphins' core habitat.
TL;DR: A strong correlation was found between oviduct fullness and nidamental glands development, which suggest that spawning is extended and intermittent in large jumbo squid.
Abstract: Ovaries of 39 large jumbo squid Dosidicus gigas (415―875 mm mantle length (ML)) of different stages of maturity from the Gulf of California and Nicaragua were analysed. Oocyte development is asynchronous during female ontogenesis, with predominance (>85 ―90%) of small protoplasmic oocytes 0.1―0.2 mm in diameter for all stages of female maturity. Potential fecundity (PF) is determined at late immature stage II with average values around 18―21 million oocytes. The maximum PF estimated, 32 million oocytes, is so far the largest recorded for any cephalopod. PF is closely related to female size. Nicaraguan females, of smaller size ( 4 15 -7 20 mm ML), show lower fecundity (5―15 million oocytes). Eggs were analysed in oviducts of mature females (540―875 mm ML), 7 from the Gulf of California and three females from Nicaragua. Eggs measured 0.9 x 1.1 mm in diameter and weighed 0.45 mg on average. The oviducts of the largest female (8 75 mm ML) held 1.2 million eggs, representing 4 .6% of PF and no more than 14% of all vitelline oocyte stock of that squid. Variability in oviduct filling is very high and unrelated to ovary weight. However, a strong correlation was found between oviduct fullness and nidamental glands development. These observations suggest that spawning is extended and intermittent. A female spawns no less than half of the initial PF, and the minimal number of spawning activity events (egg batches) is roughly estimated at 8―12. During this terminal spawning stage females continue actively feeding and grow between egg-mass laying periods.
TL;DR: There is evidence that the changes in composition of the macrobenthic infauna were driven by fishing impacts, but also influenced by the trend in climate warming and altered fluxes of phytoplankton to the benthos.
Abstract: Since 1971 the macro-benthic infauna at Station P, 185 km off the Northumberland coast (central western North Sea), have been sampled by grabbing each January/February The data series now includes over 260 taxa from 173 genera The most abundant taxa are Heteromastus, Levinsinia and Priospio which between them account for nearly 45% of the individuals recorded while the top 10 ranked taxa between them include almost 70% of the individuals recorded Both total abundance and genera richness have varied through the 36 year series, particularly during the late 1980s - early 1990s but there was no trend and values in the 20005 are similar to those at the start of the series However, MDS ordination of the entire genera abundance series shows a trend in composition of the macrobenthos through time There is evidence that the changes in composition were driven by fishing impacts, but also influenced by the trend in climate warming and altered fluxes of phytoplankton to the benthos Given that the dominant taxa have not changed and the total abundance and richness are similar this implies a turnover and redistribution of individuals across many taxa and raises the possibility of shifts in the ecological functioning of the system
TL;DR: In both species, a tendency was observed for the egg mass to increase with size of females, and the capture per unit of effort presented the lowest values in summer, while the largest values occurred from March, August and November.
Abstract: The capture of crabs of the genus Callinectes is one of the oldest extractive activities practised by waterside communities, due to the abundance of brachyurans along the Brazilian coast. The present paper aimed to provide basic information on the population biology of C. sapidus and C. danae during the period of December 2003 to November 2004, in Babitonga Bay, Joinville, Santa Catarina. The size of the first maturation of C. danae was estimated as 7.1 cm in total carapace width for females, and as 8.6 cm for males. Fecundity of the 20 females of C. danae with carapace width from 7.0 to 11.0 cm varied from 618,667 to 811,267 eggs. Fecundity of C. sapidus was higher, with a median of 978,000 eggs per female, but carapace widths in this species were also larger, with the highest frequency of females attaining 19.01 cm on average. In both species, a tendency was observed for the egg mass to increase with size of females. The capture per unit of effort presented the lowest values in summer, while the largest values occurred from March, August and November. A total of 80 males and 117 females of C. sapidus were captured in the four collecting areas, with the largest abundances in Area III (45.18%), followed by Areas II, IV and I. The size of the first maturation of C. sapidus was estimated as 10.2 cm for females and as 9.0 cm for males. Fishing effort was in relative equilibrium for adult stock (males = 58.75% and females = 52.99%) and juveniles (males = 41.25% and females = 47.01%). The largest monthly rates of biomass of C. sapidus occurred from April to November, with a peak of capture in August, without significant differences in the participation of males and females.
TL;DR: A total of 870 blue sharks ranging from 70 to 349 cm in total length (LT) were sampled from the swordfish longline fishery in the Mediterranean Sea during the period 1998–2003 and Gonad observation revealed that females smaller than 120 cm LT had immature ovaries with no mature oocytes, while mature Ovaries with visible yolky oocytes were present in specimens larger than 203 cm LT.
Abstract: A total of 870 blue sharks ranging from 70 to 349 cm in total length (LT) were sampled from the swordfish longline fishery in the Mediterranean Sea during the period 1998–2003. Males predominated and the sex-ratio (1:1.8) showed an increase in the proportion of males as size of fish increased. Gonad observation revealed that females smaller than 120 cm LT had immature ovaries with no mature oocytes, while mature ovaries with visible yolky oocytes were present in specimens larger than 203 cm LT. Ovary weight varied from 4–137 g and maximum oocyte diameter was 21.1 mm in mature females. All males smaller than 125 cm LT were immature while males larger than 187 cm LT were mature, as indicated by the presence of heavily calcified claspers, which extended beyond the posterior end of the pelvic fins. Length at 50% maturity (L50) was estimated to be 202.9 cm LT for males and 214.7 cm LT for females. Age estimates using caudal vertebrae ranged from 1 to 12 years, while age at 50% maturity was estimated at 4.9 years for males and 5.5 year for females.
TL;DR: The spatial variation in abundance and composition of subtidal meiobenthos communities was studied in two Portuguese estuaries under distinct degrees of anthropogenic pressure and suggests natural stressors may be the major factors controlling the physicochemical conditions that determine meiOBenthos community patterns.
Abstract: The spatial variation in abundance and composition of subtidal meiobenthos communities was studied in two Portuguese estuaries under distinct degrees of anthropogenic pressure. Samples were collected from 20 sampling stations along both estuarine gradients from freshwater ( 30). Of these stations 11 were located in the Mondego estuary, a system exposed to high anthropogenic stress, and 9 in the Mira estuary, a naturally stressed system located inside the Natural Park ‘Costa Vicentina’ (south-western coast of Portugal).Total meiobenthos density was higher in the Mira estuary and in both estuaries the community was dominated by nematodes. Among the twelve taxa identified in the Mira estuary, Harpacticoid copepods and Polychaeta were the second and the third most abundant groups respectively. In the Mondego estuary, Polychaeta was the second while Harpacticoid copepods was the third most abundant group in the thirteen total taxa recorded.Estuarine gradients of salinity, particles size and water nutrients were clearly detected in both estuaries and there was significant spatial heterogeneity in abundance and composition of the subtidal meiobenthos communities along these environmental gradients. Accordingly, three distinct sections were identified in both estuaries: (i) freshwater sections, where total density, and density of nematodes and Harpacticoid copepods reached minimum values; (ii) oligohaline and mesohaline sections, where the total density was low and diversity was poor; and (iii) polyhaline and euhaline sections, where both total density and diversity reached the highest values.The similar spatial distribution of meiobenthos assemblages in both estuaries suggests that natural stressors may be the major factors controlling the physicochemical conditions that determine meiobenthos community patterns. The mesoscale variability of subtidal meiobenthos density and composition within estuaries (in the order of kilometres) seems to be more important than the variability between estuaries (at the scale of hundreds of kilometres), a common feature in intertidal systems. From the management point of view, these results, based on higher taxa resolution, represent an obvious constraint to the applicability of ecological quality evaluation tools.
TL;DR: The results highlight a feeding strategy that is more related to the habitat of the species than to the food availability and underlining a food partitioning that prevents competitive exclusion between swordfish and spearfish.
Abstract: The present study attempts to give information on the resource partitioning between the Mediterranean spearfish (Tetrapturus belone) and the swordfish (Xiphias gladius). The contents of 53 T. belone and 95 X. gladius non-empty stomachs were analysed from specimens caught in the central Mediterranean Sea (Strait of Messina), from 2004 to 2006, by the harpoon fishery. Daily catches (expressed as number of fish) showed the contemporary occurrence of both species in the studied area then allowing direct comparison of diets. Epipelagic fish were the dominant prey (%IRI = 99.1) of T. belone. Eight families were identified among them, with the dominance of Belonidae and Clupeidae, which represented 40.9% and 36.8%, respectively, of the total preyed items in terms of %IRI and were mostly composed of Sardinella aurita and Belone belone. Xiphias gladius preyed mainly on teleosts and cephalopods, which represented 59% and 39.1%, respectively, of the total preyed items in terms of %IRI. Eleven teleost and five cephalopod families were recognized among them with the dominance of Trichiuridae (IRI% = 30.5) and Ommastrephidae (IRI% = 27.6). The first was represented only by Lepidopus caudatus (IRI% = 30.5), while the latter by the squid Todarodes sagittatus (IRI% = 21.1) and Illex coindettii (IRI% = 6.5). Results of a multivariate statistical analysis demonstrated that the dietary compositions differed significantly between swordfish and spearfish. Diet overlap analysed with the Schoener and Horn indices showed low values (0.23 and 0.21 for the two indices) underlining a food partitioning that prevents competitive exclusion. Our results highlight a feeding strategy that is more related to the habitat of the species than to the food availability. In fact, migration patterns of the two predators are quite different. Swordfish show vertical migrations from o to 800 m while spearfish are characterized by limited migrations, ranging between o and 200 m depths. The observation of specific prey items in the stomach content of both billfish confirmed the bathymetric range of their migrations.
TL;DR: The seasonality of feeding, low density, rarity of large feeding aggregations, prey selection and aspects of the feeding behaviour, that is, generally only consuming the coral's coenenchyme (the polyps surviving), suggest that while D. rugosa is widespread in Hong Kong, and contrary to other views, it poses little, if any, threat to local coral communities.
Abstract: Sixteen coral sites in the coastal waters of Hong Kong were examined for the corallivorous muricid gastropods Drupella rugosa and Cronia margariticola. These were recorded from all sites where there was significant hard coral cover and observed feeding upon species of Platygyra, Leptastrea, Stylocoeniella, Porites, Favites, Cyphastrea, Goniastrea, Favia, Acropora, Montipora, Pavona, Lithophyllon, Hydnophora, Echinophyllia and Plesiastrea. One large aggregation (∼2000 individuals) of mainly, D. rugosa was observed but much smaller groups (<20 individuals) were more typical. Five sites were chosen for more detailed study and surveyed during winter and summer. Despite being characterized by different coral communities, inter-site densities of D. rugosa were not significantly different and, usually, ∼2 individuals · m 2 were recorded. Seasonal differences were, however, significant with numbers greater during the summer, possibly related to reproduction. Feeding activity followed a similar pattern and was also largely confined to summer. Prey selection by Drupella rugosa was complex in the field and changed according to the relative abundance of each coral taxon. Acropora was strongly selected for at all sites where it was present and Montipora, Platygyra and Pavona were usually fed upon in greater proportions than their abundances. Leptastrea, Cyphastrea, Favites, Favia and Goniastrea were fed upon but in proportions lower than suggested by their abundances. Goniopora was never fed upon despite being relatively common. The seasonality of feeding, low density, rarity oflarge feeding aggregations, prey selection and aspects of the feeding behaviour, that is, generally only consuming the coral's coenenchyme (the polyps surviving), suggest that while D. rugosa is widespread in Hong Kong, and contrary to other views, it poses little, if any, threat to local coral communities. Thus, reported feeding clusters of D. rugosa are probably not 'plague' outbreaks but examples of seasonally fostered 'aggregations' of feeding (and probably reproducing) individuals. Indeed, no 'plague-like' outbreak of any species of Drupella has been reported upon in the literature since 1999.
TL;DR: The spatial and temporal variations of the microphytoplankton communities were examined during four oceanographic cruises conducted between July 2005 and March 2007 aboard the RV ‘Hannibal’.
Abstract: The spatial and temporal variations of the microphytoplankton communities were examined during four oceanographic cruises conducted between July 2005 and March 2007 aboard the RV ‘Hannibal’. Water thermal stratification started in May–June, and a thermocline established at 20 m depth, but ranged between 25 m during July and more than 30 m during September. The high concentrations of chlorophyll-a were observed during the May–June semi-mixed conditions and were mainly correlated with the concentrations of phosphate, suggesting a potential limitation by this nutrient. The Bacillariophyceae were dominant in the coastal samples, whereas they declined in the offshore area, most likely due to silicate shortage. Cyanobacteriae developed over semi-mixed conditions and at the thermocline depth. Relatively constant abundance of dinoflagellates was observed during the sampling periods from the coast to the offshore area, mainly explained by the high diversity species of this group. The results suggest that some phytoplankton taxa are generally adapted to specific hydrological conditions, whereas the dinoflagellates did not seem to follow this trend. Our findings have important biogeochemical implications in relationship with the export fluxes of the particulate matter throughout the water column.
TL;DR: Data show that scaldfish is a selective feeder and consumes similar prey items in the three gulfs, although between-site differences in the relative prey abundance in the stomachs were detected, and changes in the source of carbon were evident between juveniles and adults, evidencing a shift from a suprabenthic to a benthic diet.
Abstract: This study assesses the effects of bottom trawling on the feeding ecology of the scaldfish Arnoglossus laterna, by contrasting diets in an untrawled area and in two trawled areas off northern Sicily (western Mediterranean): the Gulf of Castellammare (which hosts a 200 km2 no-trawl area) and the gulfs of Termini Imerese and Sant'Agata. Scaldfish were collected in May–June 2005 using a commercial otter trawler between 40 and 80 m on muddy bottoms. Our data show that scaldfish is a selective feeder and consumes similar prey items in the three gulfs, although between-site differences in the relative prey abundance in the stomachs were detected. In the three gulfs scaldfish fed mainly on the crab Goneplax rhomboides and on the fish Lesueurigobius suerii, but there was an increase in the consumption of L. suerii and the shrimp Alpheus glaber in the trawled areas. Ontogenetic changes were evident in the diet of scaldfish, with juveniles preying mainly upon suprabenthic species, e.g. mysids and small decapods. While significant differences occurred in the diet of juveniles among all areas due to natural spatial variability, variations in the diet of adults, which feed on benthic prey, occurred between untrawled and trawled areas. These variations were clearly due to trawling disturbance, and no significant difference was detected in the diet of adults between the two trawled areas. On the contrary, the trophic level (δ15N values) of scaldfish did not vary between trawled and untrawled areas and between juveniles and adults. Changes in the source of carbon, as detected by δ13C values, were evident between juveniles and adults, evidencing a shift from a suprabenthic (juveniles) to a benthic (adults) diet.
TL;DR: The results showed that abundance of eukaryotic microorganisms decreased with increasing salinity of the ponds whereas prokaryotes were abundant in the hyper-saline ponds.
Abstract: The distribution of abundance and biomass of prokaryotes, flagellates, ciliates and phytoplankton, were studied in five ponds of increasing salinity in the Sfax solar saltern (Tunisia) coupled with environmental factors. The results showed that abundance of eukaryotic microorganisms decreased with increasing salinity of the ponds whereas prokaryotes (heterotrophic bacteria and Archaea) were abundant in the hyper-saline ponds. Phototrophic picoplankton was found in a large range of salinity values (70 and 200‰). Phototrophic non-flagellated nanoplankton which dominated in the first sampled pond was substituted by phototrophic flagellated nanoplankton in the other ponds. Heterotrophic nanoplankton dominated in the crystallizer pond but its quantitative importance declined in the less saline ponds. Diatoms and dinoflagellates were the major contributors to phytoplankton abundance in the first ponds (>90% of total abundance). Ciliated protozoa were found in all the ponds except in the crystallizer in which prokaryotes proliferated. Oligotrichida and Heterotrichida were the most abundant ciliate groups. Overall, species richness decreased with salinity gradient. We propose a simplified diagram of the Sfax saltern's food web showing the dominant role of the microbial loop along the salinity gradient.
TL;DR: Results suggest that breeding periods are becoming longer in southern species and shorter in northern species, with well-defined breeding and resting periods.
Abstract: The reproductive cycles of four limpet species, Patella depressa, Patella ulyssiponensis, Patella vulgata and Patella rustica are described for several locations in northern and central Portugal. Patella depressa and P. ulyssiponensis displayed almost continual gonad activity, with two main spawning periods, September–January and March–June, and minor spawning events dispersed throughout the year. Patella vulgata and P. rustica exhibited highly synchronized reproductive cycles, with well-defined breeding and resting periods. Gonad development in P. vulgata started in September and spawning took place from November–December to March. In P. rustica development started in June and spawning occurred from September–October to December–January. Compared to the 1980s these results suggest that breeding periods are becoming longer in southern species and shorter in northern species.
TL;DR: As high individual variations occurred in response to tagging of harbour porpoises, it is not possible to give general advice based on the factors investigated, on how to reduce stress during handling, but pouring water over the animal and lowering it into the water seem to stabilize a stressed animal.
Abstract: During satellite tagging of harbour porpoises (Phocoena phocoena), heart rate, respiration rate and cortisol value were measured to evaluate stress effects during handling and tagging. Respiration rates were obtained using video recordings, heart rates were recorded and serum cortisol levels were analysed from blood samples. Differences in heart rates, respiration rates and cortisol levels before and during the tagging events were investigated. An overall significant decrease of 31.5% in respiration rate was found during the tagging event period, while mature porpoises respired significantly more often than immature individuals. Though significant differences in heart rates were found for some individuals, no general significant change for all animals was detected. We found no correlation between cortisol concentration and either heart rate or respiration rate, nor did we find any relationships between cortisol and month of year, sex and body length. As high individual variations occurred in response to tagging of harbour porpoises, it is not possible to give general advice based on the factors investigated, on how to reduce stress during handling. However, pouring water over the animal and lowering it into the water seem to stabilize a stressed animal. Therefore, general precaution and individual judgement based on experience is essential when handling wild harbour porpoises.
TL;DR: The diagnosis of Pionosyllis is emended, and five new genera are proposed: SynmerosyllIS, Basidiosyllis, Westheidesyllis; Perkinsyllis and Brevicirrosyllis, which are newly named within the frame of a new Linnean classified group.
Abstract: Pionosyllis Malmgren, 1867 is revised based on a cladistic analysis of the 41 species considered herein as valid, two newly described species in this paper (Basidiosyllis victoriae and Opisthodonta russelli), 11 species from other genera actually belonging, or related to, Pionosyllis, and 13 syllid species from different subfamilies The phylogenetic analysis is based on 55 characters; a strict consensus of 1200 equally parsimonious trees (length = 314 steps) was obtained The clades containing species usually included within Pionosyllis are newly named within the frame of a new Linnean classification of the group (except for one, belonging to another subfamily) The diagnosis of Pionosyllis is emended, and five new genera are proposed: Synmerosyllis, Basidiosyllis, Westheidesyllis, Perkinsyllis and Brevicirrosyllis Paraehlersia San Martin, 2003, proved to be closely related to Pionosyllis Seven species are transferred to Opisthodonta Langerhans, 1879, here emended, and three transferred to Nudisyllis Knox & Cameron, 1970 (according to San Martin & Hutchings, 2006) Opisthodonta uraga (Imajima, 1966) comb nov and Perkinsyllis longisetosa comb nov are redescribed Pionosyllis compacta Malmgren, 1867, P stylifera Ehlers, 1913, P gigantea Moore, 1908, P enigmatica (Wesenberg-Lund, 1950), and Nudisyllis magnidens (Day, 1953) comb nov, are redescribed Pionosyllis marquesensis Monro, 1939 and P procera Hartman, 1965 likely belong to the Syllinae, thus they are not treated in the taxonomic account