Effects of salmon farming on benthic Crustacea

Scotland is the largest aquaculture producer in the European Union and utilizes almost all of its fjords for salmon culture. Recent UK policy has encouraged the movement of farm cages away from enclosed sites to areas with strong tidal flow because salmon farms are known to cause organic-enrichment of muddy substrata in areas with low tidal flow. This has resulted in a spate of applications to site cages over coralline algal gravel beds (termed maerl) that are usually strongly tidal and provide habitat for a diverse array of benthic Crustacea. In 2003 we studied the effects of farm waste on benthic crustaceans from a large salmon farm in Shetland that had been situated above a maerl bed since 1991. Annual monitoring reports showed a die-back of living maerl, periods of anoxia and an accumulation of organic material on the seabed within 25 m of the cages. Assessments of crustacean assemblages, quantified using 0.5-mm-sieved replicate (n = 5 per site) core samples, showed significant reductions in biodiversity near the farm. Some scavengers (e.g., the amphipod Socarnes erythrophthalmus) were far more abundant near the cages than at distances &gt;75 m from the cages, but many small crustaceans (e.g., the tanaids Leptognathia breviremis, Typhlotanais microcheles and Psudoparatanais batei; the cumaceans Nannastacus unguiculatus, Cumella pygmaea and Vaunthompsonia cristata; and the amphipod Austrosyrrhoe fimbriatus) were impoverished near the cages. We found that benthic Crustacea were significantly impacted by the salmon farm, despite the presence of strong currents, probably due to the combined effects of organic wastes and the use of toxins to combat parasitic copepods. We recommend that "fallowing", whereby farm cages are moved between sites to allow benthic recovery, is not carried out at sites where long-lived biogenic habitats such as maerl occur because this will likely increase the area of habitat degradation. </jats:p

The impact of CO2 emissions on 'nuisance' marine species

Anthropogenic CO2 emissions are being taken up from the atmosphere by the oceans, increasing the availability of dissolved inorganic carbon but reducing both the carbonate saturation and pH of seawater. This ocean acidification affects biological processes in a wide range of marine taxa. Here, we assess the likely responses of 'nuisance' species to ocean acidification, meaning those organisms that have undesirable effects from a human perspective. Based on a synthesis of evidence available to date, we predict increased growth and toxicity in harmful algal bloom species, and a significant increase in invasive algae in response to increased CO2 availability. Blooms of stinging jellyfish are also expected to increase since they are highly resilient to acidification. The effects of ocean acidification on invasive molluscs (eg, oyster drills), damaging echinoderms (eg, crown-of-thorns starfish), and a wide range of nuisance taxa will vary depending on species and location. In the USA, for example, the invasive crab Carcinus maenas is resilient to projected increases in CO2 and its impact on marine communities is expected to increase since it feeds on organisms that respond to ocean acidification with weaker defensive traits and lower recruitment. Conversely, the Red King Crab, Paralithodes camtschaticus, is adversely affected by acidification and so is expected to die back in the Barents Sea which it has invaded. Overall, we suspect that there will be an increase in nuisance species, as many have traits that are resilient to the combined warming and acidification caused by rising CO2 levels; region-specific assessments are needed to understand responses of nuisance species in local habitats. Finally, we highlight the need for targeted studies of the effects of global change on particularly harmful marine taxa such as the seaweed Caulerpa taxifolia, the starfish Asterias amurensis, several invasive ascidians, and the lionfish Pterois volitans

Student authoring, editing and electronic publishing

Millions of term papers have been written by college seniors who will be writing reports and publications as part of their professional responsibilities soon after graduation. While most term papers are graded and returned to student authors, a former student shared the observation that nothing less than an \u27A\u27 is acceptable on the job. Writing assignments can be made more meaningful by giving student authors responsibility for their writing similar to those professionals have; their work will be edited, read and used by others. Student papers were first published on the Department\u27s Cooperative Learning Center (CLC) local area network in 1991, after development of the Educators Software Package (ESP) for preparing hypertext information systems. Since then, over 2000 files have been published by CLC students in several courses. An immediate improvement in the quality of writing is observed when students know that the criterion for excellence is acceptable for publication, and their papers will be read by students for years to come. Editorial guidelines remind students that disciplined scientific writing is different from creative writing as a result of the comments of student editors. The student-authored information systems, complimented by professionally-authored files, are accessed through course, subject, and species menus. Search functions enable students to find information on our CLC network that others have written, and links to libraries and the World-Wide Web provide access to other publications. While the information on our CLC network is of significant value to the students, the greater long-term value lies in the development of professional responsibilities for writing and editing. Rather than writing a term paper and taking what they get for a grade, our students write and rewrite until their paper is accepted for publication. Student editors, graduate assistants, and course professors help the students reach that goal, and when it is reached, everyone benefits, including students in the future

Seasonal and depth-driven changes in rhodolith bed structure and associated macroalgae off Arvoredo island (southeastern Brazil)

Rhodoliths are formed by coralline red algae and can form heterogeneous substrata with high biodiversity. Here we describe a rhodolith bed at the southern limit of the known distribution of this habitat in the western Atlantic. We characterized rhodolith and macroalgal assemblages at 5, 10 and 15. m depth during summer and winter. Lithothamnion crispatum was dominant amongst the six rhodolith-forming species present. Most rhodoliths were spheroidal in shape indicating high mobility due to water movement. Rhodolith density decreased with increasing depth and during winter. Turf-forming seaweeds accounted for 60% of the biomass growing on rhodoliths. Macroalgae increased abundance and richness in the summer, but was similar between 5 and 15. m depth. They were less abundant and diverse than that recorded in rhodolith beds further north in Brazil. Both, season and depth, affected the structure of the macroalgae assemblages. We conclude that Lithothamniom is the most representative genus of Brazilian rhodolith beds. Summer is responsible for increasing the diversity and richness of macroalgae, as well as increasing rhodolith density. © 2013 Elsevier B.V