STRUCTURE AND DYNAMICS OF A POPULATION OF PALMARIA PALMATA (RHODOPHYTA) IN NORTHERN SPAIN¹

Abstract

Palmaria palmata (Linnaeus) O. Kuntze (Rhodophyta, Palmariaceae) is a seaweed commercially harvested for human consumption. Its population density, size structure, and frond dynamics were investigated from May 1999 to May 2001 at one intertidal locality in the northern coast of Spain, which is within the southern distributional boundary of the species in the eastern Atlantic coasts. The effect of size, age, and the life‐history phase (haploid vs. diploid) on frond growth and mortality were also evaluated. The study was carried out by mapping and monitoring fronds in the field. New fronds (macroscopic recruits or sprouts) appeared in spring, but subsequent mortality of these young fronds and detachment of the host plant led to lower density values in January. Palmaria palmata exhibited a distinctive seasonal growth cycle, with positive net growth from March to August and breakage from August to March. Interannual differences were also detected, with higher net growth in 2000 than in 1999. Net growth was apparently independent of age, reproductive status (fertile vs. reproductive), and life‐history phase (haploid vs. diploid) but was dependent on size, as longer fronds showed minor growth or greater breakage than small ones. Mortality, on the other hand, was more dependent on age than on size in the period analyzed (March–May 2000). Results of the study indicate that both size and age should be included as state variables and temporal changes in transition probabilities considered in the development of demographic models of the species.

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

“…The range of growth rates is higher than that recorded from some non-aquaculture field samples, e.g., Faes and Viejo (2003), suggesting the growth rates for P. palmata in the Fundy region significantly exceed those in other regions (e.g., Spain, N. Ireland).…”

“…Environmental factors such as light level, water temperature, average wave height, etc., result in an intrinsic growth rate that is time-dependent (Faes and Viejo 2003). For instance, unpublished data from Northern Ireland showed that Palmaria palmata exhibited dominating growth in the summer months, whereas dominating decay through frond breakage occurred from August to March.…”

“…In an open-sea cultivation study, the maximal growth rate of Dulse was 14% of the initial fresh weight per day (Martínez et al 2006). On the other hand, in the natural environment, maximal specific growth rates reported range from 0.89% (Northern Ireland unpublished) to 1.5% (Spain) (Faes and Viejo 2003).…”

Recent developments in aquaculture of Palmaria palmata (Linnaeus) (Weber & Mohr 1805): cultivation and uses

“…However, the red seaweed does not survive temperatures above 20°C, limiting its ongrowth in summer and early autumn for some locations. Therefore, during the summer months, at sea, culture of P. palmata is not suitable in all locations, as high temperatures and irradiances can lead to a 'photoinhibition' (bleaching) of Palmaria fronds (Dion & Del epine 1981; Sanderson et al 2012), and a naturally occurring disintegration of frond tips (Mart ınez & Rico 2002;Faes & Viejo 2003;Edwards & Dring 2011). Choosing a site, where it is possible to deepen the nets or droppers if temperature and irradiance become critical, could extend the growth phase and can be beneficial for harvest results.…”

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

“…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). …”