DIFFERENTIAL EFFECTS OF SEDIMENTS ON SURVIVAL AND GROWTH OF FUCUS SERRATUS EMBRYOS (FUCALES, PHAEOPHYCEAE)¹

Abstract

Recruitment of seaweeds through small reproductive stages is limited on sediment inundated rocky shores and largely unsuccessful in soft sediment environments. Burial in sediment has several potentially negative effects for seaweed propagules, and these effects were differentiated in a laboratory experiment. We investigated how light deprivation, sediment type (grain size, organic content, and origin), and sediment chemistry (oxygen presence and toxicity through hydrogen sulfide) affected survivorship and growth of Fucus serratus L. embryos. Presence of hydrogen sulfide had overriding negative impacts on both survivorship and growth of Fucus embryos, independently of sediment type and light availability. In contrast, simple anaerobiosis generally did not impair survival or growth of the embryos. Fine sediments, 3 mm thick, significantly reduced embryo survivorship, presumably through accumulation of metabolic waste products in the immediate vicinity of the embryos as a consequence of constrained diffusion. This effect was equally pronounced in the presence of a 1‐mm layer of organically rich biodeposits. Irradiance levels did not affect survival of embryos but influenced growth. Decreasing thickness and increasing coarseness of sediments together represented a gradient of enhanced light penetration and diffusion. Growth of embryos increased along this gradient. In nature, soft sediment environments with organically enriched muds (e.g. tidal flats and salt marshes) represent habitats least favorable for colonization through small reproductive stages of seaweeds.

Interspecific competition between Enteromorpha (Ulvales: Chlorophyceae) and Fucus (Fucales: Phaeophyceae) germlings: effects of nutrient concentration, temperature, and settlement density

“…Although fucoid algae could be negatively influenced by secondary factors often associated with eutrophication, such as toxic wastes (Wikström et al 2000) and increased sedimentation (Chapman & Fletcher 2002, Eriksson et al 2002, their decline has commonly been attributed to competitive displacement by ephemeral algae. According to this hypothesis, ephemeral algae should benefit more from nutrient enrichment and/or be less negatively affected by other factors associated with eutrophication than the declining fucoids.…”

Effects of Pilayella littoralis on Fucus vesiculosus recruitment: implications for community composition

“…The positive effect of high concentrations of exudates on Fucus survival may indicate a process of germling 'hardening' -i.e. the surviving germlings have become more resistant during exposure to adverse conditions (Chapman & Fletcher 2002). It may also be reasonable to believe that the higher concentrations of exudates contained substances that stimulated surviving germlings.…”

Measuring Rates and Effects of Dredging-Induced Sedimentation: Results From a Survey of Experts

“…Fucus serratus embryos responded negatively to thicker layers of sediment, with a stronger negative reaction to fine and organically enriched sediments, and most strongly to the presence of sulfide (Chapman and Fletcher, 2002).…”

“…Based on species and life stages of concern, benthic fish eggs and larvae are highest priority and may be most tractable based on scale. Eggs and embryos can be on the milliliter scale (see Chapman and Fletcher 2002), whereas larvae and juveniles may require many liters to even mesocosm scales. Complexity of scaling effects becomes more difficult as the scale of organism increases.…”