Foraging patterns of two syngnathid fishes: importance of harpacticoid copepods

The diets of juvenile ( less than 90 mm) Syngnathus scovelli and of Hippocampus zosterae, abundant members of a resident fish community in a Thalassia testudnum seagrass bed in Tampa Bay, Florida, were examined from Apnl to October 1984. Harpacticoid copepods comprised most of the diet, both in terms of percent number and percent biomass, for the smaller size classes of S. scovelli and for H. zosterae, and harpacticoids generally had the highest index of relative importance (IRI) for both syngnathids. S. scovelli displayed ontogenetic switching to larger food items, such as amphipods. shrimp and crustacean eggs. Harpacticus sp. 1 was the most common harpacticoid copepod species found in the guts of the 2 syngnathids, but was only rarely encountered in prey samples from seagrass blades. Three other harpacticoids, Paradactylopodia brevicornis sp., Dactylopodia tisboides and Harpacticus sp. 2 had high IRIS in H. zosterae but not in S. scovelli. Vanderploeg & Scavia's selectivity index (E') was calculated for sampling dates when both species of syngnathids were most abundant, using prey density on seagrass blades as a measure of prey avadabhty. Only the harpacticoid Harpacticus sp. 1 had high positive selectivity values

Response of small motile epifauna to complexity of epiphytic algae on seagrass blades

Field collections and experiments were performed to examine the relationship between the biomass of epiphytic algae (= habitat complexity) on Thalassia testudinum blades and the density of associated motile epifauna. Samples collected at Egmont Key, Florida indicated a significant positive association between the density of harpacticoid copepods, the most numerous taxon on seagrass blades, and biomass of the dominant epiphyte, Giffordia mitchelliae. Similar results were noted for nematodes, amphipods, and crustacean nauplii. Seagrass blades with large amounts of epiphytic algae are often older than blades with lesser amounts of algae, and have had a longer time to be colonized by epifauna. A recolonization experiment was conducted in a T. testudinum bed in the Indian River lagoon, Florida examining associations between the density of epifauna on blades of the “same” age (blades defaunated and replanted in the field) with various amounts of epiphytes. After 2 days a significant positive relationship between epiphyte biomass and density of dominant epifauna (copepods, crustacean nauplii, and nematodes) was recorded, suggesting that results were attributable to differential amounts of epiphytic algae since length of colonization time did not vary among blades. Recolonization experiments in a T. testudinum bed at Ft. Desoto, Florida using artificial blades (polypropylene ribbon) and 3 densities (no, intermediate, and high) of artificial epiphytes (clumps of cotton-polyester thread) produced results comparable to those above within 3 days. Highest densities of dominant epifauna (copepods, nematodes, and polychaetes) were found on blades in the high epiphyte treatment. Mean numbers of copepods and also polychaetes on high and intermediate epiphyte treatments were not significantly different from each other, but were significantly higher than on blades with no epiphytes. Nematode densities declined significantly with decreasing amounts of artificial epiphytes. These results suggest that much of the relationship observed between motile epifauna and epiphytic algae on seagrass blades may be attributed to the physical structure of the algae, given the similar responses of most fauna to both living and artificial plant material. The pattern observed for harpacticoid copepods and epiphytic algae on seagrass blades in field collections and experiments varied among species. Laophontid sp., Harpacticus sp., and Diosaccus sp. were strongly positively associated with the amount of epiphytic algae, however, Amphiascus sp., Ectinosomatid spp., and Dactylopodia tisboides showed little association. The results of this study demonstrate that relationships which have been shown for larger plant structure and fauna also hold for small motile epifauna and fine scale vegetative architecture

Community unity: Experimental evidence for meiofauna and macrofauna

The response of two different size classes of marine benthos, macrofauna and meiofauna, to manipulation of disturbance/predation and size specific utilization of biogenic structural refuges by each benthic size category were studied in an intertidal sandflat in Virginia. A field investigation was conducted during August and September 1980 in the same Diopatra tube system which Woodin (1978; 1981) previously utilized for macrofauna I experiments. Predator/disturber exclusion cages were employed to experimentally evaluate changes in patterns of abundance of both meiofauna and macrofauna in areas of varying Diopatra tube densities (0, 1, 3 or 6 Diopatra 0.01 m–2). Samples were collected for macrofauna and meiofauna in areas immediately adjacent to tubes (= inner) and in outer areas with no tubes present from all treatment (caged or uncaged) and tube density (0, 1, 3, 6) combinations after 2 and 4 weeks. A significant increase in total macrofaunal polychaetes, nematodes and copepods was recorded inside cages after 2 and 4 weeks. Those species which were numerically abundant in control sites were also dominant inside cages. Adult densities of the bivalve, Gemma gemma increased inside cages after 2 weeks but declined dramatically after 4 weeks. Juvenile Gemma abundances, unlike those of the adults, increased inside enclosures after both 2 and 4 weeks. Along with the density increases noted in cages, a variety of main effects (i.e., tube number or position) and interactions were revealed, but these were not consistent even among benthos of similar sizes. Although densities of both meiofauna and selected macrofauna increased over similar time scales in response to predator/disturber exclusion, their spatial patterns and relationships with tubes were highly variable. Our analyses of spatial patterns of macrofauna and meiofauna in caged and uncaged sites do not fit our a priori predictions necessary to support a refuge hypothesis for all meiofauna and macrofauna by Diopatra tubes. The discrepancies between the findings of this study and earlier reports of macrofaunal utilization of Diopatra tube-caps as refuges may be related to yearly changes in community composition and/or predator/disturber activity or possibly the time scale of experiments reported here. We suggest that simultaneous monitoring of various size classes from soft-bottom communities, coupled with field experimentation, would provide valuable insight into the relative importance of forces organizing soft-bottom assemblages

The benthic community of the eastern US continental shelf: A literature synopsis of benthic faunal resources

The existing scientific literature on offshore benthic assemblages (OBA) residing along the US East and Gulf of Mexico continental shelf was reviewed. Identification was made of any associations between the dominant OBA and particular sediment types and/or bathymetry. Of special interest was the evaluation of reported effects of sand dredge/mining activities on the dominant OBA and recognition of data deficiencies. One hundred and twenty-two references were selected and classified as to type of study with pertinent results extracted. Polychaetes were predominantly cited as the principal infaunal taxa present in studies from both the Gulf of Mexico and US Atlantic coast. Specifically, Prionospio cristata, Nephtys incisa, N. picta, and Spiophanes bombyx were consistently identified as a common part of the benthic community structure. Surveys from the East Coast indicated a greater diversity of dominant taxa not reported for the Gulf of Mexico than vice-versa. Robust animal–sediment or animal–depth relationships were not readily available. From the few studies available, it appears that general ‘‘recovery’’ from anthropogenic disturbance by benthic assemblages on the continental shelf occurs within three months to 2.5 years. Presently, it is difficult to draw conclusions about approximate benthic faunal recovery times following anthropogenic activities such as sand mining and/or disposal operations because of the paucity of studies

An Outbreak of Community-Acquired Foodborne Illness Caused by Methicillin-Resistant Staphylococcus aureus

Infections with methicillin-resistant Staphylococcus aureus (MRSA) are increasingly community acquired. We investigated an outbreak in which a food handler, food specimen, and three ill patrons were culture positive for the same toxin-producing strain of MRSA. This is the first report of an outbreak of gastrointestinal illness caused by community-acquired MRSA

Emergence of Hemagglutinin Mutations during the Course of Influenza Infection

Influenza remains a significant cause of disease mortality. The ongoing threat of influenza infection is partly attributable to the emergence of new mutations in the influenza genome. Among the influenza viral gene products, the hemagglutinin (HA) glycoprotein plays a critical role in influenza pathogenesis, is the target for vaccines and accumulates new mutations that may alter the efficacy of immunization. To study the emergence of HA mutations during the course of infection, we employed a deep-targeted sequencing method. We used samples from 17 patients with active H1N1 or H3N2 influenza infections. These patients were not treated with antivirals. In addition, we had samples from five patients who were analyzed longitudinally. Thus, we determined the quantitative changes in the fractional representation of HA mutations during the course of infection. Across individuals in the study, a series of novel HA mutations directly altered the HA coding sequence were identified. Serial viral sampling revealed HA mutations that either were stable, expanded or were reduced in representation during the course of the infection. Overall, we demonstrated the emergence of unique mutations specific to an infected individual and temporal genetic variation during infection

Selecting peach varieties for the Willamette Valley

Published September 1984. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo