Population ecology of Palmaria palmata (Palmariales, Rhodophyta) from harvested and non-harvested shores on Digby Neck, Nova Scotia, Canada

Abstract

Population ecology of Palmaria palmata is described from the intertidal zone of Digby Neck and adjacent islands of Nova Scotia. The primary objectives were: to evaluate the difference in habitat specialization and population structure of P. palmata between harvest and non-harvest shores, and to characterize differences in thallus structure and frond sizes between epilithic and epiphytic populations. Harvest shores were gently sloping boulder fields with boulders typically about 0.5-1.0 m with dense cover of P. palmata on many of the rocks. Non-harvest shores (with or without P. palmata) consisted of boulders that were smaller or larger than harvest shores, or bedrock; when P. palmata was present on nonharvest sites it was typically epiphytic on other algae (e.g., Fucus spp., Mastocarpus stellatus, Devaleraea ramentacea). Harvestable epiphytic populations occurred only in high current areas. While there was little difference in average cover of P. palmata harvest and non-harvest shores (31.2 ± 13.7% vs. 19.4 ± 7.3%, mean ± standard deviation [SD]), the cover of P. palmata on harvest shores was highly skewed such that individual boulders often had >90% cover while adjacent rocks had little. Frond length of large fronds was greater on harvested shores, and mean frond density (g m -2 ) was three times higher than the mean density on the non-harvested shores. Frond lengths of entire epiphytic and epilithic frond complements of 119 thalli from harvest beaches showed no difference in mean size of the largest fronds, and no difference in frond number per holdfast when epiphytic and epilithic thalli were compared.Key Words: Digby Neck; Dulse; Nova Scotia; Palmaria palmata; Palmariales; population ecology; seaweed harvesting INTRODUCTIONThe red alga Palmaria palmata (Linnaeus) Weber et Mohr is widely distributed in the cold waters of the North Atlantic and Arctic Oceans (Irvine and Guiry 1983, Bird and Van der Meer 1993, Guiry and Guiry 2011. Despite its cold water affinities, P. palmata occurs in warm temperate waters far south as New Jersey in the western Atlantic Ocean (Taylor 1957) and Portugal in Europe, with localized large populations in northern Spain (Faes and Viejo 2003). Throughout its range P. palmata may be an epiphyte, and it typically occurs in the low intertidal and subtidal zones to depths of about 20 m (Irvine and Guiry 1983, Faes and Viejo 2003, Vadas et al. 2004).In eastern Canada P. palmata occurs from the Bay of Fundy through to the Gulf of St. Lawrence and the island of Newfoundland (Taylor 1957, Edelstein et al. 1970, Wilson et al. 1979, South and Hooper 1980, South et al. 1988. In the outer reaches of the Bay of Fundy, this species can become abundant, and it forms the basis of commercial harvests (MacFarlane 1964, 1966, Ffrench 1974, Chopin and Ugarte 2006. P. palmata has a long history Received December 26, 2011, Accepted February 29, 2012 *Corresponding Author E-mail: dgarbary@gmail.com Tel: +1-902-867-2164+1-902-867- , Fax: +1-902-867-2389 This is an Open Access article distributed under ...

A mathematical model of the commercial harvest of Palmaria palmata (Palmariales, Rhodophyta) on Digby Neck, Nova Scotia, Canada

“…During late summer and fall fronds become increasing reproductive with spermatagia or tetrasporangia. Over the winter many large reproductive fronds may remain in the population, but as these fronds senesce the population becomes increasingly dominated by the new fronds developing from the holdfasts (Garbary et al 2012, Katelyn White unpublished data). We do not have sufficient information on the relative importance of vegetative regeneration from holdfasts (vs. reproduction through tetraspores) to effectively study the population from a multi-year perspective.…”

“…This is especially surprising for P. palmata given the paucity of study of the regional ecology in the context of resource management. Indeed, the current study, and the related paper by Garbary et al (2012) are the first detailed studies of Dulse ecology in Nova Scotia, and the first to document the state of the resource rather than simply harvest amounts (e.g., MacFarlane 1966, Ffrench 1974 or growth rates based on tank cultivation (e.g., Morgan et al 1980, Morgan and Simpson 1981a, 1981b, Corey et al 2011.…”

Concise review of the red macroalga dulse, Palmaria palmata (L.) Weber & Mohr

“…It is also commonly found as an epiphyte on other macroalgae, especially on the stipes of the kelp Laminaria hyperborea (Fig. 3) and Laminaria digitata, and fronds of Fucus serratus and Cystoseira baccata (Faes and Viejo 2003;Garbary et al 2012). As for other marine photosynthetic organisms, light is a major factor limiting its vertical distribution.…”

The marine macroalgae of Brier Island, Nova Scotia, Canada

“…Further physiological and ecological studies were carried out on Palmaria palmata (e.g. Garbary et al 2012), Prasiola stipitata (Kang et al 2014); Ascophyllum nodosum and Vertebrata lanosa (Garbary 2017a); and Prasiola crispa (Garbary and Hill 2017). There are complementary floristic studies from the western side of the Bay of Fundy in both Canada and USA.…”