Spring Surveys Research Articles

Role of hydro-climatic and demographic processes on the spatio-temporal distribution of cephalopods in the western Mediterranean

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 514:105-118 (2014) - DOI: https://doi.org/10.3354/meps10972 Role of hydro-climatic and demographic processes on the spatio-temporal distribution of cephalopods in the western Mediterranean Patricia Puerta1,*, Manuel Hidalgo1, María González2, Antonio Esteban3, Antoni Quetglas1 1Instituto Español de Oceanografía, Centre Oceanogràfic de les Balears, Moll de Ponent s/n, Apdo. 291, 07015 Palma de Mallorca, Spain 2Instituto Español de Oceanografía, Centro Oceanográfico de Málaga, Puerto Pesquero s/n, 29640 Fuengirola, Málaga, Spain 3Instituto Español de Oceanografía, Centro Oceanográfico de Murcia, Varadero 1, 30740 San Pedro del Pinatar, Murcia, Spain *Corresponding author: patricia.puerta@ba.ieo.es, patrix.puerta@gmail.com ABSTRACT: Fluctuations in marine populations occur both in terms of abundance and distributional ranges, and this has major implications for marine ecology and fisheries management. However, little is known about the variability in, and factors influencing, spatial dynamics in marine groups other than fish. Using time series data from trawl surveys conducted in the western Mediterranean Sea from 1994 to 2012, we analysed the variability in population distribution (latitude, longitude and depth) of 2 cephalopod species with contrasting life histories, viz. the nektobenthic squid Illex coindetii and the benthic octopus Eledone cirrhosa. We investigated the influence of demographic information (population density and mean individual size) together with environmental variables (including chlorophyll a concentration, runoff, precipitation, temperature and climate) to identify the main drivers shaping the cephalopod distributions in 4 shelf regions with contrasting oceanographic and geographic conditions. Marked inter-annual fluctuations were found in the distribution of the 2 species. In general, squid and octopus populations were affected by the same variables, but the effect of each variable depended on the species and study region. Different life strategies resulted in contrasting responses to the environment, with I. coindetii associated with variables contemporary to spring surveys. In contrast, E. cirrhosa was primarily affected by conditions during the previous winter. Vertical distribution was mainly explained by individual body length, while chlorophyll, temperature or local climate proved to be more important for geographical displacements. KEY WORDS: Spatio-temporal distribution · Spatial ecology · Illex coindetii · Eledone cirrhosa · Demography · Hydro-climatic conditions Full text in pdf format Supplementary material PreviousNextCite this article as: Puerta P, Hidalgo M, González M, Esteban A, Quetglas A (2014) Role of hydro-climatic and demographic processes on the spatio-temporal distribution of cephalopods in the western Mediterranean. Mar Ecol Prog Ser 514:105-118. https://doi.org/10.3354/meps10972 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 514. Online publication date: November 06, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.

Twenty Years of Elfin Enumeration: Abundance Patterns of Five Species of Callophrys (Lycaenidae) in Central Wisconsin, USA.

We recorded five species of elfins (Callophrys) during annual spring surveys targeting frosted elfin C. irus (state-listed as threatened) in 19 pine-oak barrens in central Wisconsin USA during 1994–2013. At the northwest end of its range here, C. irus co-varied with spring temperature, but declined significantly over time (eight sites verified extant of originally 17). Two other specialists increased significantly. The northern specialist, hoary elfin C. polios (nine sites), correlated positively with the previous year’s growing season precipitation. The southern specialist, Henry’s elfin C. henrici (11 sites), co-varied with winter precipitation and spring temperature and dryness. The two resident generalists had stable trends. For all species, the first observed date per year became earlier over time and varied more than the last observed date. Thus, flight period span increased with earlier first observed dates. Elfin abundance increased significantly with earlier first observed dates in the current and/or prior year. Three species (C. irus, C. henrici, a generalist) had more positive population trends in reserves than non-reserves. This suggests that C. irus declines correspond to habitat conditions. Thus, monitoring programs and habitat management specifically for C. irus appear necessary to obtain a long-term stable trend for this species in Wisconsin.

Water temperature affects life-cycle duration of tadpoles of Natal cascade frog

Direct and indirect effects of climate change on amphibians include range shifts and changes in community structure. The Natal cascade frog Hadromophryne natalensis has an altitudinal range of some 2 400 m in KwaZulu-Natal, and presents an opportunity to assess how increased water temperatures may impact on widely distributed amphibians. We sampled populations of tadpoles at three sites near the upper and lower altitudinal extremes of their range, measuring total length, mass and habitat water temperatures. Except for the spring survey, frequency–size class data showed bimodal curves at the two high-altitude sites and unimodal curves at the low-altitude site, suggesting a two-year aquatic life cycle in the cooler, higher rivers and a one-year life cycle at the warmer site. These data were consistent with cumulative degree days, which doubled from the higher- to the lower-altitude sites. Tadpoles at the warmer, lower-altitude site were in worse condition than those at the cooler, higher-altitude sites. We hypothesise that, while thermal changes may not result in rapid, large range shifts for this species, there are a number of unknown variables that may result from potential reductions in life-cycle length, including changes in competitive behaviour and community structure linked to asynchronies between species.

Population abundance, size structure and sex-ratio in an insular lizard

Estimating population size and understanding its variation is a fundamental, yet complicated, aim of many ecological studies. We considered the problem of estimating spring and autumn population abundance, size-dependent population structure and sex-ratio of the endemic Balearic Lizard, Podarcis lilfordi from a three occasions capture-recapture study. We used a Bayesian formulation of individual covariate models to incorporate individual sex, size and trap-response. We first considered a set of simulated data with a medium-to-low probability of recapture and individual recapture heterogeneity to evaluate potential problems in model fitting and selection. Results from simulated data indicated a low performance in parameter estimation and model selection when probability of detection was low (0.15–0.30). We found a negative permanent trap response and a positive effect of size on detection probability in the spring survey but not in the autumn one. The estimated mean densities varied from about 800 to 1000lizardsha−1, a high value when comparing with mainland lizard populations. The observed increase in abundance was probably due to a drop in territorial behaviour and the immigration of females into the area sampled. As a consequence, sex-ratio changed from nearly even in June (mean posterior, 95%CRI; 0.928, 0.676–1.167) to a female-skewed population in October (0.612, 0.478–0.772).

Biological controls on resuspension and the relationship between particle size and the Kolmogorov length scale in a shallow coastal sea

Abstract Measurements of suspended particle matter (SPM) and turbulence have been obtained over five tidal surveys during spring and summer 2010 at station L4 (50.25° N 04.22° W, depth 50 m), in the Western English Channel. The relationship between turbulence intensity and bed stress is explored, with an in-line holographic imaging system evaluating the extent to which material is resuspended. Image analysis allows for the identification of SPM above a size threshold of 200 μm, capturing particle variability across tidal cycles and the two seasons. Dissipation of turbulent kinetic energy, which exceeds 10− 5 W kg− 1, yields maximum values of bed stress of between 0.17 and 0.20 N m− 2, frequently resulting in the resuspension of material from the bed. Resuspension is shown to promote aggregation of SPM into flocs, where the size of such particles is theoretically determined by the Kolmogorov microscale, lk. During the spring surveys, flocs of a size larger than lk were observed, though this was not repeated during summer. It is proposed that the presence of gelatinous, biological material in spring allows flocculated particles to exceed lk. This suggests that under specific circumstances, the limiting factor on the growth of flocculated SPM is not only turbulence, as previously thought, but the presence or absence of certain types of biological particle.

Spatial and temporal distribution of Atlantic mackerel (Scomber scombrus) along the northeast coast of the United States, 1985–1999

Abstract Radlinski, M. K., Sundermeyer, M. A., Bisagni, J. J., and Cadrin, S. X. 2013. Spatial and temporal distribution of Atlantic mackerel (Scomber scombrus) along the northeast coast of the United States, 1985–1999. – ICES Journal of Marine Science, 70: 1151–1161. The distribution of Atlantic mackerel (Scomber scombrus) during their spring migration along the Mid-Atlantic Bight and into the Gulf of Maine has historically been associated with spring warming along the continental shelf. Variations in mackerel distributions based on National Marine Fisheries Service spring surveys were compared with variations in sea surface temperature (SST) from satellite remote sensing for the eastern US continental shelf for the period 1985–1999. The mackerel stock was first analysed as a unit, then separated into three size classes to assess differences in distribution among years and individuals of various lengths. Results showed an across-shelf correlation between catch and March SST in the Mid-Atlantic Bight for both the entire population and each size class. Along-shelf catch variations were correlated with SST for large mackerel, but not total stock or smaller size classes. Finally, the distribution of mackerel length in the Gulf of Maine was negatively correlated with March SST in the Great South Channel. Results suggest surface temperature along the northeast continental shelf may be used to predict certain, but not all, aspects of annual migration along the shelf, and that factors in addition to temperature are also important in controlling distributions of Atlantic mackerel.

Geophysical Monitoring of Simulated Clandestine Graves Using Electrical and Ground‐Penetrating Radar Methods: 0–3 Years After Burial*,†

This study provides forensic search teams with systematic geophysical monitoring data over simulated clandestine graves for comparison to active cases. Simulated "wrapped" and "naked" burials were created. Multigeophysical surveys were collected over a 3-year monitoring period. Bulk ground resistivity, electrical resistivity imaging, multifrequency ground-penetrating radar (GPR), and grave and background "soil-water" conductivity data were collected. Resistivity surveys revealed the naked burial had consistently low-resistivity anomalies, whereas the wrapped burial had small, varying high-resistivity anomalies. GPR 110- to 900-MHz frequency surveys showed the wrapped burial could be detected throughout, with the "naked" burial mostly resolved. Two hundred and twenty-five megahertz frequency GPR data were optimal. "Soil-water" analyses showed rapidly increasing (year 1), slowly increasing (year 2), and decreasing (year 3) conductivity values. Results suggest resistivity and GPR surveys should be collected if target "wrapping" is unknown, with winter to spring surveys optimal. Resistivity surveys should be collected in clay-rich soils.

Polychaete response to fresh food supply at organically enriched coastal sites: Repercussion on bioturbation potential and trophic structure

We investigated the vertical distribution, abundance, specific and functional structure of polychaete assemblages at four organically enriched sites. The effects of fresh organic matter input from the water column driving by upwelling were evaluated. Temperature and salinity values indicate the intrusion of South Atlantic Central Water (SACW) in spring, a nutrient-rich water mass. The dominance of the conveyor belt transport (CONV) in the station influenced by SACW, in the spring survey, is associated with fresh organic matter input as indicated by higher amounts of polyunsaturated fatty acids. Conversely, the predominance of the diffusive mixing (DIFF) bioturbation category, in the sites without SACW influence is related to the preferential accumulation of more refractive food resources as indicated by higher concentrations of short chain saturated fatty acids. At the site influenced by SACW, the changes in polychaete assemblages were not all evident during proceeding upwelling conditions, but may persist at the end of the upwelling. Polychaetes in the study area seemed to be limited by the quality but not the quantity of food. The delay in polychaete response to fresh food supply may be related to the organic enrichment and the prevalence of refractory material in the sediments.

Parasitoids of the painted apple moth Teia anartoides Walker (Lepidoptera: Lymantriidae) in Australia

Painted apple moth Teia anartoides Walker (Lepidoptera: Lymantriidae), a native to Australia, was discovered in Auckland, New Zealand in late 1999 and eradicated by 2006. It was recognised in 2002 that biological control would be the most effective long-term control strategy if eradication was unsuccessful, and a search was initiated for potential biocontrol agents in Australia. In 2003, autumn and spring surveys were undertaken in Victoria, Tasmania and South Australia of the guild of parasitoid natural enemies of T. anartoides. Eggs, larvae and pupae were collected and held to rear out any parasitoids. In addition, localised searches were made in Queensland in late 2003 early 2004 and laboratory-reared juvenile stages of T. anartoides were released for recapture in both Victoria and Queensland. Acacia dealbata Link (Fabales: Fabaceae) was the main plant from which T. anartoides was recovered, followed by apple. Most T. anartoides samples were collected from Victoria and Tasmania. Eighteen species from 13 genera of egg, larval and pupal parasitoids were reared and included Diptera (Tachinidae) and Hymenoptera (Braconidae, Encyrtidae, Eulophidae and Ichneumonidae). Of the seven Hymenopteran genera recovered from the larval stage, the most common in Victoria and Tasmania was a previously unidentified larval parasitoid Cotesia Cameron (Hymenoptera: Braconidae) sp. Echthromorpha intricatoria (Fabricius) (Hymenoptera: Ichneumonidae) was the dominant pupal parasitoid. The survey showed that the parasitoid complex associated with T anartoides is structurally very similar to that on other pest Lymantriidae in the northern hemisphere such as gypsy moth (Lymantria dispar L.) (Lepidoptera: Lymantriidae). Meteorus pulchricornis (Wesmael) (Hymenoptera: Braconidae) was recorded for the first time in Australia.

Spatial variability and temporal dynamics of surface water pCO 2, ΔO 2/Ar and dimethylsulfide in the Ross Sea, Antarctica

We report results from two surveys of pCO 2, biological O 2 saturation (ΔO 2/Ar) and dimethylsulfide (DMS) in surface waters of the Ross Sea polynya. Measurements were made during early spring (November 2006–December 2006) and mid-summer (December 2005–January 2006) using ship-board membrane inlet mass spectrometry (MIMS) for high spatial resolution ( i.e. sub-km) analysis. During the early spring survey, the polynya was in the initial stages of development and exhibited a rapid increase in open water area and phytoplankton biomass over the course of our ∼3 week occupation. We observed a rapid transition from a net heterotrophic ice-covered system (supersaturated pCO 2 and undersaturated O 2) to a high productivity regime associated with a Phaeocystis-dominated phytoplankton bloom. The timing of the early spring phytoplankton bloom was closely tied to increasing sea surface temperature across the polynya, as well as reduced wind speeds and ice cover, leading to enhanced vertical stratification. There was a strong correlation between pCO 2, ΔO 2/Ar, DMS and chlorophyll a (Chl a) during the spring phytoplankton bloom, indicating a strong biological imprint on gas distributions. Box model calculations suggest that pCO 2 drawdown was largely attributable to net community production, while gas exchange and shoaling mixed layers also exerted a strong control on the re-equilibration of mixed layer Ο 2 with the overlying atmosphere. DMS concentrations were closely coupled to Phaeocystis biomass across the early spring polynya, with maximum concentrations exceeding 100 nM. During the summer cruise, we sampled a large net autotrophic polynya, shortly after the seasonal peak in phytoplankton productivity. Both diatoms and Phaeocystis were abundant in the phytoplankton assemblages during this time. Minimum pCO 2 was less than 100 ppm, while ΔO 2/Ar exceeded 30% in some regions. Mean DMS concentrations were ∼2-fold lower than during the spring, although the range of concentrations was similar between the two surveys. There was a significant correlation between pCO 2, ΔO 2/Ar and Chl a across the summer polynya, but the strength of these correlations and the slope of O 2 vs. CO 2 relationship were significantly lower than during the early spring. Summertime DMS concentrations were not significantly correlated to phytoplankton biomass (Chl a), pCO 2 or ΔO 2/Ar. In contrast to the early spring time, there were no clear temporal trends in summertime gas concentrations. Rather, small-scale spatial variability, likely resulting from mixing and localized sea-ice melt, was clearly evident in surface gas distributions across the polynya. Analysis of length-scale dependent variability demonstrated that much of the spatial variance in surface water gases occurred at scales of <20 km, suggesting that high resolution analysis is needed to fully capture biogeochemical heterogeneity in this system.

Waterfowl population survey of the Marcali reservoir (2007–2008)

This study has shown that the Marcali reservoir is an important waterbird wetland habitat especially during the migration period. Based on our findings early springtime season proved to be the most important season concerning bird activities on the reservoir. The reservoir and its surroundings are not specifically important as breeding areas; although, some strictly protected species can be found among the breeding species. It is noteworthy to mention the strong disturbance (waterfolw hunting, intensive fishing, poaching) in the area that can have a negative impact on the breeding success of bird species. The results of similarity measures showed remarkable differences between the bird communities of different seasons. Waterbird communities of the spring season and summer season showed the highest similarity, since part of the species observed during the spring surveys were most probably breeding species that remained in the reservoir area for the summer. Comparison based on bird species diversity showed significant differences between communities of the different seasons. Diversity was higher both in the breeding and the migration season compared with the winter period characterized by the lowest species richness and number of individuals. Water level has proved to be an important determining factor of waterbird species richness.

Influencing Adolescent Social Perceptions of Alcohol Use to Facilitate Change through a School-Based Intervention

The current study examines the effectiveness of a voluntary high school-based alcohol intervention by investigating one proposed mechanism of change in adolescent alcohol involvement: perception of peer use. High school students reporting lifetime drinking (N = 2055) completed fall and spring surveys that assessed demographic information, substance use, risk factors, and intervention attendance (N = 327). The motivational enhancement-based intervention used school and grade-specific normative data to facilitate change in adolescent perceptions regarding the frequency and quantity of peer alcohol use. Results indicate that intervention participants were more likely to increase the accuracy of their peer frequency estimates over the course of the year in comparison to the general student body. Furthermore, students demonstrating decreases in peer perceptions of alcohol use exhibited a greater reduction in number of binge episodes, lower maximum number of drinks consumed per episode, and average number of drinks consumed per drinking occasion (ps < .05); teens with the greatest alcohol use history demonstrated the largest reductions. Although we found no significant main effect for intervention attendance, findings support the role of reduced peer drinking estimates in decreasing alcohol involvement among teen drinkers.

Temporal and spatial distribution of floating objects in coastal waters of central–southern Chile and Patagonian fjords

Floating objects are suggested to be the principal vector for the transport and dispersal of marine invertebrates with direct development as well as catalysts for carbon and nutrient recycling in accumulation areas. The first step in identifying the ecological relevance of floating objects in a specific area is to identify their spatio-temporal distribution. We evaluated the composition, abundance, distribution, and temporal variability of floating objects along the continental coast of central–southern Chile (33–42°S) and the Patagonian fjords (42–50°S) using ship surveys conducted in austral winter (July/August) and spring (November) of the years 2002–2005 and 2008. Potential sources of floating items were identified with the aid of publicly available databases and scientific reports. We found three main types of floating objects, namely floating marine debris (mainly plastic objects and Styrofoam), wood (trunks and branches), and floating kelps ( Macrocystis pyrifera and Durvillaea antarctica). Floating marine debris were abundant along most of the examined transects, with markedly lower abundances toward the southern fjord areas. Floating marine debris abundances generally corresponded to the distribution of human activities, and were highest in the Interior Sea of Chiloé, where aquaculture activities are intense. Floating wood appeared sporadically in the study area, often close to the main rivers. In accordance with seasonal river run-off, wood was more abundant along the continental coast in winter (rainy season) and in the Patagonian fjords during the spring surveys (snow melt). Densities of the two floating kelp species were similar along the continental coast, without a clear seasonal pattern. M. pyrifera densities increased towards the south, peaking in the Patagonian fjords, where it was dominant over D. antarctica. Densities of M. pyrifera in the Patagonian fjords were highest in spring. Correlation analyses between the abundances of floating objects and the distance to the nearest sources were generally non-significant, suggesting that post-supply processes affect the distribution of the floating objects in the study region. The identification of several major retention zones supports this idea. Accumulation areas of floating objects appear to be more common in the fjord zones. In general, the results underscore the abundance of floating objects throughout the study region and the fact that floating marine debris sources are mostly local, whereas floating algae may be dispersed over greater distances. Future studies should focus on the ecological role of floating objects in biota dispersal and nutrient cycling.

Biological Diversity Associated with Bigtooth Aspen Patches in a Mixed Oak Landscape

Abstract This study evaluated the ability of bigtooth aspen (Populus grandidentata Michx.) patches to contribute to the understory diversity of southeastern Ohio's mixed oak forests by providing unique microenvironments embedded within the larger mixed vegetation matrix. Twenty bigtooth aspen patches and adjacent mixed oak forest were selected for study. Microenvironmental parameters were assessed in both the patch and surrounding matrix and included light, relative humidity, soil and air temperature, soil moisture, nitrate, texture, pH, O and A horizon depth, organic matter content, and cation (Mg, Ca, P, K, Al) availability. Spring and summer vegetation surveys were conducted to investigate differences in floristic composition between aspen patches and surrounding forest. A MANOVA revealed significant (P < 0.001) differences in the microenvironment between aspen patches and the oak matrix resulting from differences in soil texture, organic matter content, soil and air temperature, soil pH, magnesium, ca...

Soil cultivation, nitrogen fertilization and weeds

The cultivation methods used in the experiments resulted in marked differences in the weediness of maize and wheat. The least weediness was found in the conventional tillage treatment. The crucial question in the conservation and no tillage for sustainable agriculture is the weed problem, especially if the technology of weed controls is unaltered as compare to the traditional one. The lower yield in this cultivation system can be attributed to the competition of weeds. To clarify the question, investigations were carried out in the years 2005–2008 in a long-term field experiment set up on brown forest soil at the University of Pannonia, Georgikon Faculty Keszthely. The lowest yields were obtained in the wheat–maize no-tillage system in comparison to the others. This was valid at high and low levels alike (good and unfavorable years). On the average of years the yield decrease was 10–15% as compared to the traditional cultivation. In the spring survey of the weed cover (%) in the wheat trials it was found that the weed coverage increased parallel with the N fertilizer amounts, and then declined in the treatment above 200 kg N. The relation of weeds v.s. N fertilizer is similar to the second power equation of the yield curve. In case of the maize trials, there were no significant differences between the N treatments (25–30%) regarding weed coverage. The gained results call attention to the fact that with the propagation of the reduced soil cultivation systems it is necessary to modify and harmonize the practice of weed control and fertilization. Instead of the schematic weed control and fertilization process, the application of scientifically well-established methods should be urged. In sustainable agriculture the data collection of weeds, the survey of dominant species, special herbicide combinations and the means of precision agriculture have to be taken into consideration.

Ecological changes in the highest temporary pond of western Crete (Greece): past, present and future

This study explores the past, present and future ecological changes in the highest Mediterranean temporary pond (Omalos pond) in western Crete, Greece. Data from downcore pollen analysis (including pollen and spores from both aquatic vegetation, and terrestrial herbaceous, arboreal and shrub vegetation), modern vegetation monitoring and existing climate scenarios have been combined to provide a picture of the ecological changes in the pond over the last 13,600 years. Downcore pollen analysis throughout the last 13,600 years indicated the presence of species typical of Mediterranean Temporary Pond (MTP) habitats and suggested relatively drier conditions towards the present. The low number of non-native, cultivated species (such as herbaceous Trifolium and Plantago species) observed over this period suggested relatively low impact from crop agriculture, despite the increasing grazing pressure in the area. In the absence of independent proxies, we cannot reliably distinguish between natural and human-induced changes. The presence of aquatic Isoetes in the palaeo-record indicates the existence of an ephemeral pond in the area as early as the beginning of the Holocene suggesting resilience of the ecosystem over time. However, the degraded state of pollen in depths over 55 cm (i.e. 3600 year BP) increases the uncertainty of the interpretation. Currently, the pond holds 76 plant species belonging to 25 families. Therophytes and chamaephytes were the most frequent, suggesting a typical ephemeral habitat life form spectrum. Species richness was found to increase during spring surveys whereas the highest turnover was observed between summer surveys of consecutive years. Cluster analysis demonstrated a distinct zonation in four vegetation belts from the periphery to the centre of the pond which is typical of these environments. Modelling, based on two IPPC scenarios (A2 and B2), predicted relatively low climate change impacts on the pond’s hydroperiod for the next 100 years (i.e. a decrease of 16 and 24 days, respectively). This reduction in the hydroperiod of the pond will have an effect on the physiognomy and spatial extent of vegetation, particularly for the transitional belts between the core and its outer area, while it will exert more pressure on the pond as a water resource for sheep in the region. However, cumulative effects and complex interactions of climate-driven environmental changes and other anthropogenic disturbances might act synergistically to accelerate impacts in the future.

Ecology of megabenthic bivalve communities from sandy beaches on the south coast of Portugal

Ecological aspects of 75 megabenthic bivalve species found on the south coast of Portugal (from Vila Real to Sagres) were studied based on the information provided by seasonal bivalve surveys from 2000 to 2007 (8600 hauls, simultaneously using a razor shell dredge and a clam dredge). Of the 75 species identified, 36 occurred less than 30 times, and thus were considered rare in the area. The remaining 39 bivalves were analysed according to their occurrence, bathymetric distribution, geographic preferences, seasonal preferences, burying-depth, beach exposure and river mouth proximity. All species belonging to the Pharidae and Solenidae families (razor shells) and most Tellinidae were significantly more frequent in the razor shell dredge (indicating deeper burying in the sediment), whilst the families Cardiidae and Donacidae were significantly more frequent in the clam dredge (indicating that these species are probably closer to the sediment surface). As for the season, most bivalve species occurred similarly in both seasons (19 sp; 49%), but a large proportion were more abundant during the autumn surveys (17 sp., 44%), whereas only three species were commoner during the spring surveys. Most species belonging to the families Cardiidae and Mactridae were commoner in the autumn surveys. The spatial distribution differed between species and cluster analysis identified four communities with greater geographic affinity. Species belonging to the family Cardiidae were preferably found in the western part (WB) and the eastern part (S) of the study area, whereas the families Donacidae, Mactridae and Tellinidae occurred mainly in the central area (EB) and the eastern (S) coastal sectors. Overall, shallower species (modal depth at 3-6 m) showed greater occurrences and abundances than the deeper ones, and the depth pattern observed did not change between seasons. Donacidae and Mactridae (except Mactra glauca ) were represented essentially by shallow species, whereas Cardiidae (except Acanthocardia tuberculata and Cerastoderma edule ) included mostly species occurring in deeper waters. Bathymetric sequence of species distribution within some families was observed.

Bathymetric and longitudinal distribution analyysis of the rockfish Helicolenus Dactylopterus (Delaroche, 1809) in the southern Tyrrhenian Sea (central Mediterranean)

This study provides information on bathymetric and longitudinal distribution heterogeneity of the rockfish Helicolenus dactylopterus in the southern Tyrrhenian Sea. Data were drawn from experimental bottom trawl (1996-2002) plus bottom trap (2001-02) surveys. The frequency of occurrence and mean relative density (N/km2) and biomass (kg/km2) indexes were calculated for two survey seasons (spring and autumn), four geographic sectors and three depth strata. MANOVA was used to test fish abundance among years, sectors and strata. Analysis of the length-frequency distributions was carried out by two-way (gears and depths) ANOVA, post hoc multiple comparisons for testing differences among depths and Student’s t test for testing differences between gears. Length-weight relationship was also estimated and the allometric coefficient was tested with the Student’s t test. The results showed a significant positive bathymetric gradient of sizes both for trawl and trap surveys; at same depths, fish caught by traps were significantly longer than those caught by trawl. In spring surveys, significant differences were found among strata for both abundance indexes; in autumn surveys, significant differences between depth strata were found only for density indices. The distribution and abundance patterns of H. dactylopterus along the southern Tyrrhenian Sea was homogeneous among sectors. Length-weight relationship showed a significant positive allometric growth.

Larval fish abundance and physical forcing in the Gulf of Alaska, 1981–2003

The present study investigates ecological patterns and relationships to environmental variables among a time-series of larval fish species abundance from late spring surveys (1981–2003) in the northwest Gulf of Alaska (GOA). Links between interannual variation in species abundance and the physical environment were explored using generalized additive modeling (GAM). Trends in larval abundance and connections with physical variables displayed patterns that indicate unique and complex responses among species to environmental forcing during the larval period. In particular, the observed patterns suggest that ontogenetic-specific responses, representing sub-intervals of early life, are important. In addition, a notable degree of synchrony in larval abundance trends, and similarity in links with physical variables, were observed among species with common early life history patterns. The deepwater spawners, northern lampfish, arrowtooth flounder, and Pacific halibut, were most abundant in the study area during the 1990s, in association with enhanced wind-driven onshore and alongshore transport. Years of high abundance for Pacific cod, walleye pollock, and northern rock sole were associated with cooler winters and enhanced alongshore winds during spring. High larval abundance for spring–summer spawning rockfish species and southern rock sole seemed to be favored by warmer spring temperatures later in the time-series. This apparent exposure–response coupling seems to be connected to both local-scale and basin-scale environmental signals, to varying degrees depending on specific early life history characteristics. Understanding such ecological connections contributes to the evaluation of vulnerability and resilience among GOA species’ early life history patterns to fluctuating climate and oceanographic conditions. This investigation also provides crucial information for the identification of “environmental indicators” that may have a broad-spectrum effect on multiple species early life history stages, as well as those that may be more species-specific in exerting control on early life history survival. Of particular interest was the emergence of the EP–NP (East Pacific–North Pacific) teleconnection index as the top-ranked variable in the GAM models exploring the connections between late spring larval abundance and the physical environment. The EP–NP index represents an important and often primary mode of spring–summer atmospheric variability in the northeast Pacific, with a strong expression in the GOA, and its connection with species in this study implies that it may be a climate mode of significant ecological importance.

DIVISION III / SERVICE MINOR PLANET CENTER

The activity of the Minor Planet Center continued generally to increase during the two triennia covered by this report, principally because of the continuing success of the surveys for near-earth objects. Chief among these has been the Lincoln (Laboratory) Near-Earth Asteroid Research Project, or LINEAR, which is credited with the discovery of slightly more than half of all the minor planets that have been numbered, although since 2005 the Catalina Sky Survey and Mount Lemmon Survey in Arizona and the Siding Spring Survey in New South Wales (all three of which, together with the long-lasting Spacewatch Survey, are operated from the University of Arizona) have come to dominate the field. The total number of observations of minor planets in the MPC's files more than doubled from 14.1 million in mid-2002 to 30.9 million in mid-2005, with almost another doubling, to 55.4 million, in mid-2008.