Published August 30 Vol. 13: 237-248. 1983 Sedimentation of organic and inorganic particulate material in LindPspollene, a stratified, land-locked fjord in western Norway MARINE ECOLOGY - PROGRESS SERIES Mar. Ecol. Prog. Ser. Paul Wassmann Institute of Marine Biology, University of Bergen. N-5065 Blomsterdalen. Norway ABSTRACT: Sedimentation of particulate material to the bottom (90 m) was measured in Lindbspol- lene, a land-locked, highly stratified, west Norwegian fjord, receiving fresh water from a small glacier free watershed. Five cylindrical sediment traps positioned at 10, 20, 40, 70, and 85 m below the surface were exposed from April to November. Organic material con~prised 40 to 60 % of the sedimented matter. Sedimentation rates of particulate inorganic material (PIM) and particulate organic carbon (POC) decreased from 229 and 111 at 20 m to 71 and 22 g rn-'yr-', respectively, in the deeper water. Possible reasons for the low sedimentation in the stagnant water below 40 m are high mineralization rates in the upper 40 m and the lack of resuspension in the water below. Three pulses of POC and PON (particulate organic nitrogen) reached the bottom related to phytoplankton blooms in April and May. The pulse in April was the largest and the sedimented material consisted of unidentified aggregates, diatoms and some few fecal pellets. Few recognizable structures were found in the samples below 20 m except in April. This might indicate a low zooplankton grazing efficiency in April, but a high efficiency during the rest of the investigation period. INTRODUCTION Little is known about seasonal and depth-related changes in sedimentation of particulate material in Norwegian fjords. Wassmann (1981) and Gulliksen (1982) applied sediment traps to measure the supply of particulate material to the sediment surface in respec- tively Fanafjorden and Balsfjorden, whereas Skei (1983) measured the sedimentation in the poll Fram- varen. I present here the first data concerning the supply of particulate material to the sediment of Lindbspollene, a west Norwegian, highly stratified, land-locked fjord (Fig. 1). The supply of particulate matter to the sedi- ment depends partly on changes in the structure and function of the pelagic system. Monitoring the sedimentation cycle is, therefore, one important step towards the understanding of marine ecosystems (Smetacek, 1980a). The investigation is part of a pro- ject at the Institute of Marine Biology, University of Bergen. The ultimate aim of this project is to develop a dynamic mathematical model of the flows of energy and matter in the ecosystem (Dahl et al., 1973). The settling of particles through the water column O Inter-Research/Printed in F. R. Germany and onto the sea bed has been subject of thorough investigations in different parts of the world for about 2 decades (Table 5). This flux represents a loss of particulate organic matter from the euphotic zone and the main source of food and energy for the benthos and planktonic organisms living below this zone. The sink- ing of particles is also of interest for chemical and geochemical processes in the water column as well as in the sediment. Small, land-locked fjords ('polls') are very common along the west coast of Norway. Despite extensive investigations of 'polls' in the twenties and thirties (Gaarder, 1932; Gaarder and Bjerkan, 1934 ; Alvik, 1934; Str~m, 1936) little research has been done in Norway on such ecosystems until the sixties (e.g. Dybern, 1967; Lannergren, 1975, 1976, 1978; Dale, 1978; Skjoldal and Lannergren, 1978). Land-locked fjords have specific topographic, hy- drodynamic and biological characteristics, such as shallow sills, limited water exchange and stagnant bottom waters, and food chains which differ from those of more open fjords (Matthews and Heimdal, 1980). Land-locked fjords differ so much from typical fjords that it has been suggested that the Norwegian word