In 2006 and 2007, multiple deployments of current meters and optical sensors on landers and moorings were made in the first detailed in situ study of the particle supply to the coral community in the Mingulay Reef complex in the Sea of Hebrides at 140-m water depth. Two distinct and predictable supply mechanisms were resolved. One mechanism consisted of the rapid downwelling of surface water caused by hydraulic control of tidal flow that transports particles from the surface to the corals in less than an hour. The rapid downwelling was recorded on the reef top as a pulse of warm, fluorescent, and relatively clear water at the onset of the flood and ebb tides. The pulse was strongest after flood tide and lasted for up to 3 h. The second mechanism consisted of advection onto the reef of deep bottom water with a high suspended matter load. This advection occurred during peak tides and was combined with topographical current acceleration on the reef top, enhancing delivery of particles to the corals.

The number of offshore wind farms is increasing rapidly, leading to questions about the environmental impact of such farms. In the Netherlands, an extensive monitoring programme is being executed at the first offshore wind farm (Offshore Windfarm Egmond aan Zee, OWEZ). This letter compiles the short-term (two years) results on a large number of faunal groups obtained so far. Impacts were expected from the new hard substratum, the moving rotor blades, possible underwater noise and the exclusion of fisheries. The results indicate no short-term effects on the benthos in the sandy area between the generators, while the new hard substratum of the monopiles and the scouring protection led to the establishment of new species and new fauna communities. Bivalve recruitment was not impacted by the OWEZ wind farm. Species composition of recruits in OWEZ and the surrounding reference areas is correlated with mud content of the sediment and water depth irrespective the presence of OWEZ. Recruit abundances in OWEZ were correlated with mud content, most likely to be attributed not to the presence of the farm but to the absence of fisheries. The fish community was highly dynamic both in time and space. So far, only minor effects upon fish assemblages especially near the monopiles have been observed. Some fish species, such as cod, seem to find shelter inside the farm. More porpoise clicks were recorded inside the farm than in the reference areas outside the farm. Several bird species seem to avoid the park while others are indifferent or are even attracted. The effects of the wind farm on a highly variable ecosystem are described. Overall, the OWEZ wind farm acts as a new type of habitat with a higher biodiversity of benthic organisms, a possibly increased use of the area by the benthos, fish, marine mammals and some bird species and a decreased use by several other bird species.

Predation by the brown shrimp Crangon crangon causes a significant density-dependent mortality of 0-group plaice during and shortly after settling on tidal flats in the western Wadden Sea between February and May. Evidence was obtained from (1) laboratory experiments indicating that larger shrimps are able to prey on plaice S 3 0 mm; (2) field observations showing that each year the period of density-dependent mortality ends in May-June when the plaice population has reached a mean size of about 30 mm; (3) the occurrence of fin damage in the field, characteristic of unsuccessful attacks by shrimps, according to laboratory experiments; and (4) shrimp stomachs containing significant numbers of plaice otohths. The shrimp predation is density-dependent and accounts for the total mortahty in plaice 6 3 5 mm as estimated in a previous paper (van der Veer 1986). The observed dependence of mortality on density appears to be caused by the combined effect of a functional and numerical response of the predator to fluctuations in plaice density. The number of fin damages of a plaice does not seem to influence its survival. Predation by larger crabs seems to be of minor importance and occurs only after May. Shrimp predation appears to act as a fine control mechanism reducing between-year variations in year-class strength generated in the egg or larval stages in the open sea.

The Mingulay reef complex in the Sea of the Hebrides west of Scotland was first mapped in 2003 with a further survey in 2006 revealing previously unknown live coral reef areas at 120 to 190 m depth. Habitat mapping confirmed that distinctive mounded bathymetry was formed by reefs of Lophelia pertusa with surficial coral debris dating to almost 4000 yr. Benthic lander and mooring deployments revealed 2 dominant food supply mechanisms to the reefs: a regular rapid downwelling of surface water delivering pulses of warm fluorescent water, and periodic advection of high turbidity bottom waters. Closed chamber respirometry studies suggest that L. pertusa responds to seawater warming, such as that seen during the rapid downwelling events, with increases in metabolic rate. Lipid biomarker analysis implies that corals at Mingulay feed predominantly on herbivorous calanoid copepods. Integrating geophysical and hydrographical survey data allowed us to quantify the roles of these environmental factors in controlling biodiversity of attached epifaunal species across the reefs. Longitudinal structuring of these communities is striking: species richness (α) and turnover (β) change significantly west to east, with variation in community composition largely explained by bathymetric variables that are spatially structured on the reef complex. Vibro-cores through the reef mounds show abundant coral debris with significant hiatuses. High resolution side-scan sonar revealed trawl marks in areas south of the coral reefs where vessel monitoring system data showed the highest density of local fishing activity. The interdisciplinary approach in this study allowed us to record the food supply and hydrographic environment experienced by L. pertusa and determine how it may be ecophysiologically adapted to these conditions. Improved basic understanding of cold-water coral biology and biodiversity alongside efforts to map and date these long-lived habitats are vital to development of future conservation policies. KEY WORDS: Ecological engineer · Lophelia pertusa · Seamounts · Internal waves Resale or republication not permitted without written consent of the publisher Contribution to the Theme Section 'Conservation and management of deep-sea corals and coral reefs'

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We estimated the direct mortality of benthic fauna caused by one single passage of commercial beam and otter trawls in field experiments. The benthos dredge Triple-D was used to sample megafauna (>1 cm), while macrofauna (>1 mm) were sampled by means of a Reineck boxcorer and, in some cases, a van Veen grab. Direct mortalities ranging from about 5 up to 40% of the initial densities were observed for a number of gastropods, starfishes, small and medium-sized crustaceans, and annelid worms. For bivalve species, direct mortalities were found from about 20 up to 65%. Mortality per m 2 trawled area due to fishing with a 12-m beam trawl was not higher than that due to a 4-m beam trawl. For all species considered, the direct mortality was largely attributed to animals that died in the trawl track, either as a direct result of physical damage inflicted by the passage of the trawl or indirectly owing to disturbance, exposure, and subsequent predation. In 1994, the 12 m beam trawl with tickler chains was the dominant gear type in the Dutch sector, resulting in a mean annual trawling frequency of 1.23. The mean annual trawling frequencies with the 4 m beam trawl using tickler chains, the 4 m beam trawl with a chain mat, and the otter trawl were 0.13, 0.01, and 0.06, respectively. The annual fishing mortality in invertebrate megafaunal populations in the Dutch sector ranged from 5 up to 39%, with half of the species showing values of more than 20%. For all species studied, the 12 m beam-trawl fisheries caused higher annual fishing mortalities than the concerted action of the other fisheries. Only with respect to species restricted to sandy coastal areas did the 4 m beam-trawl fleet contribute substantially to the annual mortality. Implications of the impact of trawling on the composition of benthic communities are discussed. International Council for the Exploration of the SeaKey words: direct mortality of trawling, fishing mortality, impact of beam trawling, impact of otter trawling, megafauna.

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Larval immigration and subsequent settlement, abundance fluctuations, growth, and mortality of a 0-group flounder population were studied in a tidal flat area, the Balgzand, in the western Wadden Sea. Larvae entered the area from early April to early May. The first settled flounder were found about 1 mo after larval immigration started. Settled flounder were restricted to the siltier areas of the tidal flats. Growth did not seem to be food-limited within the density range observed over the years and depended only on prevailing water temperatures. The life history pattern of flounder was similar to that of plaice in the same area: year-class strength was generated in the open sea and after settlement a period of density-dependent mortality followed, most probably due to predation by crustaceans. The instantaneous mortality rate Z during summer seemed to be higher (0 08 d-l) than in plaice (0.03 dC1), probably due to a combination of higher water temperature and higher abundance of predators in summer than during the settlement of plaice in spring. No relationship between the year-class strengths of plaice and flounder was found