Deep sea without limitsfour new closely related species of Emertonia Wilson, 1932 (Copepoda: Harpacticoida: Paramesochridae) show characters with a world-wide distribution.

The large-scale dispersal of deep-sea harpacticoid copepods is an increasing focus for ecological studies. A fundamental prerequisite for monitoring and explaining their geographical distribution is precise descriptions of their morphology. Four new, closely related species of the family Paramesochridae (Copepoda, Harpacticoida) were found in the deep sea of the Pacific (San Diego Trough and off Chile), the Atlantic Ocean (Porcupine Abyssal Plain and Angola Basin), and the Atlantic and Indian Ocean sectors of the Southern Ocean (Weddell Sea and off Crozet Island). The discovery of Emertonia berndi sp. nov., E. hessleri sp. nov., E. ilse sp. nov., and E. serrata sp. nov. increases the number of known deep-sea species in this genus to ten. The new species are placed in Emertonia Wilson, 1932 because of their one-segmented endopods on the second and third swimming legs. The presence of a two-segmented endopod on the fourth swimming leg allocates them to the andeep-group within this genus. The four species can be distinguished from their congeners by the strongly serrated spines on the exopods of their swimming legs and an outwardly directed flexible seta on the exopod of the fifth leg. It is conveivable that these two specific characters evolved only once in the genus Emertonia. Their apparently cosmopolitan distribution covers thousands of kilometres and spans all major oceans. This biogeographical pattern may be explained by resuspension events followed by passive transport by benthic currents. Discrepancies in their dispersal ranges may be a result of changing geological and oceanographic boundaries.

The mitochondrial genomes of Amphiascoides atopus and Schizopera knabeni (Harpacticoida: Miraciidae) reveal similarities between the copepod orders Harpacticoida and Poecilostomatoida.

Members of subclass Copepoda are abundant, diverse, and-as a result of their variety of ecological roles in marine and freshwater environments-important, but their phylogenetic interrelationships are unclear. Recent studies of arthropods have used gene arrangements in the mitochondrial (mt) genome to infer phylogenies, but for copepods, only seven complete mt genomes have been published. These data revealed several within-order and few among-order similarities. To increase the data available for comparisons, we sequenced the complete mt genome (13,831base pairs) of Amphiascoides atopus and 10,649base pairs of the mt genome of Schizopera knabeni (both in the family Miraciidae of the order Harpacticoida). Comparison of our data to those for Tigriopus japonicus (family Harpacticidae, order Harpacticoida) revealed similarities in gene arrangement among these three species that were consistent with those found within and among families of other copepod orders. Comparison of the mt genomes of our species with those known from other copepod orders revealed the arrangement of mt genes of our Harpacticoida species to be more similar to that of Sinergasilus polycolpus (order Poecilostomatoida) than to that of T. japonicus. The similarities between S. polycolpus and our species are the first to be noted across the boundaries of copepod orders and support the possibility that mt-gene arrangement might be used to infer copepod phylogenies. We also found that our two species had extremely truncated transfer RNAs and that gene overlaps occurred much more frequently than has been reported for other copepod mt genomes.

The relative impacts of spills of two alternative fuels on the microalgae of a sandy site: a microcosm study.

Electric power generation in the United States uses substantial amounts of fuel oil #6. Orimulsion, an emulsion of bitumen, water, and a surfactant, is an alternative. A portion of the information that managers need to compare the two fuels is their relative environmental impacts. Both fuels are shipped by sea, so the impact of spills on the marine benthos is a concern. We used microcosms to assess the relative impacts of simulated spills of these fuels on the microalgae of shallow subtidal sandy bottoms. Response variables included microalgal abundance, primary productivity, ratio of chlorophyll a to phaeophytin, and ratio of primary production to chlorophyll a. During our 88-day experiment, we found no significant differences between the fuels for any variable. We suggest that weathering before the spill reaches the shore removes the most toxic components, rendering the fuels essentially equal in their impact on benthic microalgae.

A microcosm system for the study of pollution effects in shallow, sandy, subtidal communities.

The introduction of pollutants into the marine environment is inevitable, so an understanding of their effects is needed. Because shallow, coastal waters are at greatest risk and many of these shorelines are sandy, a test system for the shallow, sandy, subtidal environment is required. We developed a microcosm system for this purpose and tested it for three months to determine whether the benthic community remained healthy. Furthermore, because long-term effects on the environment occur primarily in the sediment, an experimental method for administering pollutants to the sediment is necessary. We administered a 1-mm layer of clean sand (simulating a technique of administering pollutants as a coating on sand) and tested the benthic community for artifactual effects of the sand itself. Fifteen metrics of community health, including the abundance of benthic microalgae, nematodes, and copepods, were measured. Most metrics were not significantly affected either by containment in the microcosms or by the addition of a 1-mm layer of clean sand. These microcosms are suitable as a test system for the shallow, sandy, subtidal environment.

Spills of fuel oil #6 and Orimulsion can have indistinguishable effects on the benthic meiofauna.

Fuel oil #6 is used for the production of electrical power in the United States. Orimulsion is being considered as an alternative fuel, but its value and risk compared to fuel oil #6 need to be assessed. Our study examined the relative impact of accidental spills of the two hydrocarbons on the meiofaunal community. To do so, we maintained microcosms of the shallow, sandy, subtidal environment for three months. Treatment microcosms received a single application of hydrocarbon-coated sand. As indicators of effect, we used copepod and nematode abundance and copepod species diversity, sex ratio, fecundity, age structure, and neutral-lipid content. A comparison of the hydrocarbon treatments showed no significant differences. The tests had adequate power to detect ecologically significant changes. Our results indicate that a spill of Orimulsion would have approximately the same impact as a spill of fuel oil #6 on the meiofauna.

An experimental investigation of enhanced harpacticoid (Copepoda) abundances around isolated seagrass shoots.

At a site in the Gulf of Mexico (29°54.6'N, 81°31.4'W) off the coast of northern Florida, harpacticoid copepod abundance is significantly enhanced around isolated "plants" (technically short shoots) of the seagrass Syringodium filiforme. Using inanimate mimics of seagrass short shoots, we demonstrate, in the field, that the enhanced abundance does not results from the presence of the plant as a living entity. Our experiments reveal a two-fold increase in bacterial biomass around both short shoots and mimics; the harpacticoids appear to be responding to a local increase in their resources. We suggest that the flow field around a short shoot improves the rate of supply of oxygen and other materials to sedimentary bacteria, thereby driving the effect. Given the ubiquity of structures that have similar flow effects, localized bacterial enhancement may be common and should be considered in studies of the effects of surface structures on soft-bottom community organization.