Greenshell TM mussel (Perna canaliculus) culture is the primary aquaculture industry in New Zealand. However, our knowledge of biofouling on Greenshell TM mussel farms, and its contribution to farm ecotrophic effects, is poor. We conducted a preliminary study of biofouling accumulation at two Greenshell TM mussel farms during Intermediate and Final seed on-growing stages (each of 6 months duration) with sampling of mussel ropes at 0, 3, 5 and 6 months during each on-growing stage. A diverse range of biofouling organisms (71 distinct taxa) accumulated on mussel ropes, with biofouling biomass dominated by suspension-feeding organisms (*88% of biofouling biomass) such as other bivalves, ascidians and, to a lesser degree, bryozoans. Biofouling biomass increased with culture time, varied between farms and was generally greater at 2 m than at 8 m depth. After 6 months, biofouling organisms on average comprised 54% of the total rope biomass. The reseeding of ropes between Intermediate and Final seed crops reduced the amount of non-Greenshell TM mussel biofouling. However, after 6 months, non-Greenshell TM mussel biofouling on average still comprised 15% of the total rope biomass. To evaluate potential ecotrophic effects of biofouling on Greenshell TM mussel farms, we compare the clearance rates of Greenshell TM mussel longlines based on Greenshell TM mussels alone and when combined with the two dominant biofouling species observed in our study (the mussel Mytilus galloprovincialis and the ascidian Ciona intestinalis). Our study shows that accumulated biofouling biomass on Greenshell TM mussel ropes can be significant and recommends further investigation as to actual ecotrophic effects of biofouling to ensure sustainable mussel farm practices.

Preventing the introduction of nonindigenous species (NIS) is the most efficient way to avoid the costs and impacts of biological invasions. The transport of fouling species on ship hulls is an important vector for the introduction of marine NIS. We use quantitative risk screening techniques to develop a predictive tool of the abundance and variety of organisms being transported by ocean-going yachts. We developed and calibrated an ordinal rank scale of the abundance of fouling assemblages on the hulls of international yacht hulls arriving in New Zealand. Fouling ranks were allocated to 783 international yachts that arrived in New Zealand between 2002 and 2004. Classification tree analysis was used to identify relationships between the fouling ranks and predictor variables that described the maintenance and travel history of the yachts. The fouling ranks provided reliable indications of the actual abundance and variety of fouling assemblages on the yachts and identified most (60%) yachts that had fouling on their hulls. However, classification tree models explained comparatively little of the variation in the distribution of fouling ranks (22.1%), had high misclassification rates (approximately 43%), and low predictive power. In agreement with other studies, the best model selected the age of the toxic antifouling paint on yacht hulls as the principal risk factor for hull fouling. Our study shows that the transport probability of fouling organisms is the result of a complex suite of interacting factors and that large sample sizes will be needed for calibration of robust risk models.

No abstract

The Istron area is located in northeastern Crete, Gulf of Mirabello, on an alluvial fan of Holocene age. The archaeological importance of this area is suggested not only by its archaeological remains, but also by its significant location. Many important Minoan sites, like Gournia, Kavousi, Pseira, have been discovered near Istro. There are indications of human installations from the Neolithic to the Roman period, proving the continuous human activity in this area. The significant geological location-it represents an area with intense tectonic activity-, geomorphological regime and climatic changes , have influenced regional settlement and the overall cultural development of the area. The study of sea-land interactions during the last seven millennia in relation to the eustatic sea level oscillations and the regional neotectonic regime, as well as the geomorphologic observations and analyses on deposited sediments, aims to reveal the paleogeographic evolution of the landscape and its impact on prehistoric, classical and Roman establishments. A geomorphological mapping of the coastal area along with the drilling of five boreholes and the excavation of six trenches, have therefore been accomplished. Moreover, pollen and microfaunal (benthic foraminifera and ostracodes) analyses have been performed. Six samples were dated using AMS and Conventional radiocarbon techniques providing temporal control of the sediments. Sea level rise along with sea-land interactions to the landscape evolution and the transgression of sea in 5000BP have been verified. Additionally, several implications for the use of land and human impact civilization have been made.

Phytoplankton biomass alone cannot predict growth and condition in the mussel Perna canaliculus. This study investigates whether food selection processes, low removal rates of small picophytoplankton-sized particles (0.2 to 2 μm) or additional heterotrophic food sources such as microzooplankton and bacteria may help explain this observation and therefore aid in predicting growth and condition in P. canaliculus. Three grazing experiments were run at different times of the year, using naturally varying planktonic assemblages. P. canaliculus did not feed efficiently on picophytoplankton or bacterial particles and higher filtration rates were always observed on larger phytoplankton (> 2 μm). Much of the 0.2 to 2 μm size fraction, whether heterotrophic or autotrophic, was not directly utilised for mussel growth. In terms of phytoplankton biomass, grazing and ingestion was often highest on naked flagellated cells. Results indicated that selection of some phytoplankton for ingestion was based on food quality, with both small and large naked flagellated cells with high carbon content often preferred over other morphotypes. P. canaliculus also supplemented its diet with heterotrophs, heavily grazing a range of microzooplankton. Grazing overall showed selection for naked flagellated or ciliated microzooplankton with high carbon content. The results indicate that rather than directly accessing picophytoplankton and bacteria, P. canaliculus accesses these populations through the food web by grazing upon microzooplankton, mixotrophic algae and, potentially, aggregates. This study adds to our ability to predict mussel condition by identifying key food sources for the growth of P. canaliculus.KEY WORDS: Phytoplankton · Size structure · Mussels · Picophytoplankton · Pelorus SoundResale or republication not permitted without written consent of the publisher