Production and fate of kelp detritus

Abstract

The flow of detritus between habitats is an important form of connectivity that affects regional productivity and the spatial organization of marine ecosystems. Kelps form highly productive beds or forests that produce detritus through incremental blade erosion, fragmentation of blades, and dislodgement of whole fronds and thalli. Rates of detrital production range from 8 to 2657 g C m −2 yr −1 for blade erosion and fragmentation, and from 22 to 839 g C m −2 yr −1 for loss of fronds and thalli. The estimated global average rate of detrital production by kelps is 706 g C m , accounting for 82% of annual kelp productivity. Detrital production rates are regulated by current and wave-driven hydrodynamic forces and are highest during severe storms and following blade weakening through damage by grazers and encrusting epibionts. Detritus settles within kelp beds or forests and is exported to neighboring or distant habitats, including sandy beaches, rocky intertidal shores, rocky and sedimentary subtidal areas, and the deep sea. Exported kelp detritus can provide a significant resource subsidy and enhance secondary production in these communities ranging from tens of meters to hundreds of kilometers from the source of production. Loss of kelp biomass is occurring worldwide through the combined effects of climate change, pollution, fishing, and harvesting of kelp, which can depress rates of detrital production and subsidy to adjacent communities, with large-scale consequences for productivity.KEY WORDS: Kelp bed · Kelp forest · Connectivity · Detritus · Resource subsidy · Local-regional productivity Resale or republication not permitted without written consent of the publisher

Seaweed aquaculture in Norway: recent industrial developments and future perspectives

“…Nutrient transfers form seaweeds and kelp forests to other ecosystems are key processes in nature, increasing food availability to otherwise nutrient-poor environments (Vetter 1995;Krumhansl and Scheibling 2012). However, besides acting as a temporary nutrient sink and having potentially positive effects on surrounding pelagic environments, large-scale seaweed cultivations may also cause high material deposits on the seafloor which could have adverse consequences on benthic ecosystems and biodiversity through decomposition processes and associated oxygen depletion (Viaroli et al 2008).…”

Disturbance effects of kelp thalli on structure and diversity of a coastal Arctic marine soft-bottom assemblage

“…1). Detached kelp may also persevere in and affect the fauna of coastal sedimentary habitats through partial thallus burial or increased drag from holdfast-attached rocks (Krumhansl and Scheibling 2012). Besides the continuous effects of stationary thalli, drifting seaweeds can also affect the ecology of sedimentary habitats in coastal areas (Krumhansl and Scheibling 2012).…”

“…Detached kelp may also persevere in and affect the fauna of coastal sedimentary habitats through partial thallus burial or increased drag from holdfast-attached rocks (Krumhansl and Scheibling 2012). Besides the continuous effects of stationary thalli, drifting seaweeds can also affect the ecology of sedimentary habitats in coastal areas (Krumhansl and Scheibling 2012). Soft-bottom benthos may benefit from storm-induced kelp debris as external food (Filbee-Dexter and Scheibling 2012) or through an increase in habitat complexity (Norkko and Bonsdorff 1996b).…”

“…Soft-bottom benthos may benefit from storm-induced kelp debris as external food (Filbee-Dexter and Scheibling 2012) or through an increase in habitat complexity (Norkko and Bonsdorff 1996b). Coverage by kelp, however, can disturb suspension feeding infauna through a reduction in the supply of food and oxygen (Hull 1987;Krumhansl and Scheibling 2012).…”

“…Young et al 2011), which may alter disturbance regimes and affect ecosystem properties (Hooper et al 2005). In particular, large sessile benthos like kelp will be affected by storms, provoking defoliation and export of kelp detritus to neighbouring and distant habitats (Filbee-Dexter and Scheibling 2012;Krumhansl and Scheibling 2012). The effects of waves on Arctic coastal ecosystems will amplify with the melt-down of protective sea ice.…”