Seaweed attachment to bedrock: biophysical evidence for a new geophycology paradigm

Abstract

Seaweeds are amongst the most obvious and ecologically important components of rocky shore communities worldwide but until now little has been known about the processes involved in their attachment. This multidisciplinary study investigated for the first time the interactions between marine macroalgal holdfasts and their underlying substrata, requiring the development of specialized sample preparation techniques to maintain the structural integrity of the holdfast-bedrock interface. Transmitted plane polarized light microscopy, scanning electron microscopy with energy dispersive spectroscopy and structured light illumination microscopy were used in the examination of the interface between Ascophyllum nodosum (Fucales, Heterokontophyta) and crustose red algae Lithothamnion sp. (Corallinales, Rhodophyta) on granite and limestone substrates. The new evidence presented here represents a paradigm shift in the way we view seaweed attachment because results show that the holdfasts exploit the physical characteristics of the rock-forming minerals in order to penetrate the bedrock and thus facilitate the attachment process. Mineral cleavage planes together with intercrystalline and intracrystalline boundaries and fractures provide penetration pathways for the holdfast tissue. This process causes disaggregation of rock-forming minerals to depths <10 mm and therefore assists in the bioerosion of coastal bedrock. It is concluded that seaweeds are able to cause weathering of natural rock and the term 'geophycology' is introduced to describe seaweed-bedrock interactions, including seaweed-induced weathering.

Frequency of Microplastics in Mesopelagic Fishes from the Northwest Atlantic

“…Two microplastic fibres were gold coated (Emitech K550, Quorum Technologies Ltd., West Sussex, United Kingdom) and subjected to scanning electron microscopy (SEM) in secondary electron mode using a Hitachi model S-4700 (Hitachinaka, Japan). The analyses were performed at an acceleration voltage of 20 kv, an emission current (Ic) of 10 µA and a working distance of 12 mm (Morrison et al, 2009). …”

Optimising the settlement and hatchery culture of Saccharina latissima (Phaeophyta) by manipulation of growth medium and substrate surface condition

“…(Woods and Fletcher unpublished results). Roughened areas are thought to improve the attachment strength in developing juvenile, due to the increased attachment area for the holdfast and the physical locking of holdfast rhizoids into microscopic crevices (Milligan and DeWreede 2000;Morrison et al 2009). Therefore, the improved survival seen maybe a consequence of less accidental detachment due to generally stronger attachment in the developing juveniles.…”

Simultaneous nitrate and phosphate removal from wastewater lacking organic matter through microbial oxidation of pyrrhotite coupled to nitrate reduction

“…K, Fe, S) (INCA ® ; Oxford Instruments; High Wycombe, UK). The analysis was performed at an acceleration voltage of 20 kV, an emission current (I e ) of 10 mA and a working distance of 12 mm (Morrison et al, 2009).…”