Susceptibility of Nereocystis luetkeana (Laminariales, Ochrophyta) and Eualaria fistulosa (Laminariales, Ochrophyta) spores to sedimentation

Abstract

The establishment of algal spores plays an essential role in adult kelp distribution and abundance patterns. Sedimentation is a key variable regulating algal spore settlement and success, possibly controlling species-specific dominance in situ. Laboratory experiments were used to determine spore attachment and survival rates of two Alaskan canopy-forming kelps, Nereocystis luetkeana (K. Mertens) Postels & Ruprecht and Eualaria fistulosa (Postels & Ruprecht) M. J. Wynne, to various types of sediment loading. Spore attachment for both species was significantly and similarly affected by three sediment treatments: suspended particles; settled sediment covering the substratum; and smothering of attached spores by settling sediment. Spore attachment decreased by approximately 90% at 420 mg sediment L -1, the highest sediment load tested here, under all three treatments for both species. These results suggest that increases in sedimentation may constrain the success of the spore stages, but sediment does not seem to be a likely factor explaining species-specific distribution patterns. However, while sedimentation affected spores of both species similarly, timing of spore release in relation to times of maximum sediment load in the water might differ for different species, possibly explaining kelp species distribution patterns.

Wasted effort: recruitment and persistence of kelp on algal turf

“…Chapman 1984, Connell & Russell 2010 by blocking spore settlement (Airoldi 2003, Deiman et al 2012 or creating an inimical microenvironment (reduced light, oxygen, or nutrients) for postsettlement survival of the early lifehistory stages of kelp (Daly & Mathieson 1977, Devinny & Volse 1978. As far as we are aware, our study is the first to document extensive macroscopic recruitment of kelp sporophytes to filamentous and coarsely branched turf algae in the northwest Atlantic.…”

“…Once established, turf algae can physically inhibit settlement of kelp spores by entrapping sediment (Airoldi 2003, Deiman et al 2012) and reducing the availability of coralline-covered rock upon which kelp spores normally settle (N orton & Fetter 1981, Kennelly 1987. Some species of turf algae may also chemically alter the substrate, preventing settlement of kelp spores even after the turf is removed (Kennelly 1987).…”

“…The sporophyte attaches to the rocky substrate via a holdfast, an anchoring structure with numerous branching extensions (haptera) that resists dislodgement by wave forces. Turf algae that have replaced kelp accumulate large quantities of inorganic sediment (FilbeeDexter et al 2016) that can prevent attachment of kelp spores (Devinny & Volse 1978, Deiman et al 2012, creating a physical barrier to settlement ). However, S. latissima has been reported an ecdotally to recruit on turf in the northeastern USA (Brady-Campbell et al 1984).…”

Factors influencing recruitment and appearance of bull kelp, Nereocystis luetkeana (phylum Ochrophyta)

“…Other factors that we did not explore may influence where the microscopic stages of bull kelp settle and complete their life stage transitions; for example, the effects of sedimentation as well as the combination of increased temperature and salinity may negatively influence the settlement and survival of microscopic stages (Deiman et al. , Lind and Konar ).…”

A review of protocols for the experimental release of kelp (Laminariales) zoospores

“…Zoospore release is a critical first step in the life cycle of kelps, and a prerequisite for culturing and studying their microscopic life stages. Our literature review revealed over 421 studies that utilized zoospore release protocols, with a strong bias toward ecological experiments testing zoospore and gametophyte performance under a range of environmental conditions (cf raw data provided on Dryad; see data availability statement) including temperature (Mabin, Gribben, Fischer, & Wright, ; Matson & Edwards, ; Mohring et al, ), UV radiation (Han & Kain, ; Huovinen, Oikari, Soimasuo, & Cherr, ), and sedimentation (Deiman, Iken, & Konar, ; Geange, Powell, Clemens‐Seely, & Cárdenas, ). This focus can likely be attributed to an interest in understanding the growing impacts of human activities on kelp forests.…”