The recent increase in interest about effects of trawling and dredging on seafloor ecosystems and their fisheries can be understood by examining three phases in the history of conservation thinking. The primary focus in nonmarine conservation thinking and management worldwide is on maintaining biodiversity, while marine managers are still focused mainly on use of marine life. Marine conservatio...

1 Center for Marine Environmental Ecology, School of Environment Science and Engineering, Tianjin University, Tianjin, China, 2 School of Ecology, Environment and Resources, Qinghai University for Nationalities, Xining, China, 3 Duke Marine Laboratory, Nicholas School of the Environment, Duke University, Durham, NC, United States, 4 Key Laboratory of Systems Bioengineering (Ministry of Educatio...

The urgent need to reduce the intense pressure and destructive power that modern fishing practices apply to the world’s fisheries, and the oceans that support them, is now widely recognized (e.g. FAO 2002a, Hilborn et al. 2003). However, there is far less agreement over the exact levels to which fishing mortality must be reduced and over how to reduce the indirect effects of fishing (e.g. bycat...

Nanoplankton and picoplankton abundance and community grazing on picoplankton were deterrnined in surnmer and autumn at several stations in a productive coastal environment (Georges Bank. NW Atlantic Ocean) and in an oligotrophic oceanic ecosystem (Sargasso Sea). Ranges of heterotrophic nanoplankton (HNAN) abundance were 1.2 to 3.6 X 103 ceils rnl-' on Georges Bank, and 2.2 to 6.8 X 10' ceiis m...

Microbes dominate our planet, especially the Earth’s oceans. The distinguishing feature of microorganisms is their small size, usually defined as less than 200 micrometers (μm); they are all invisible to the naked eye. As a group, sea microbes are extremely diverse, and extremely versatile with respect to their abilities to make and eat food. All marine microbes are too small to swim against th...

Previous work has shown freshwater macrophytes from lake littoral zones to be "C-enriched compared to the same species collected from fast movlng nvers It is thought that carbon fixation In aquatic plants having thicker, stagnant boundary layers, such as that w h ~ c h occurs withln low turbulence lentic systems, will result in more positive F' 'C values due to greater d~ffusion resistance and ...

A model for nutrient uptake rate (V) in phytoplankton is derived: V = n A v S / ( l + h A v S ) where n is cellular number of uptake sites, A is area of the uptake site, h is time required for handling one nutrient ion, vis the mass transfer coefficient, and S i s substrate concentration. The model is based on 2 time requirements necessary for active uptake of nutrients: (i) time required for r...

Ammonium and nitrate uptake was measured in 6 European tidal estuaries (Ems. Rhine, Scheldt, Loire, Gironde and Douro) using I5N-tracer techniques. Uptake rates of ammonium and nitrate ranged from 0.005 to 1.56 pmol N 1-' h-I and 0.00025 to 0.25 pmol N 1-' h-I, respectively, and differed significantly between and within estuaries. Analysis of nitrogen uptake using the relative preferential inde...