MEPS 543:153-162 (2016)  -  DOI: https://doi.org/10.3354/meps11566

ABSTRACT: Previous research on the Laminariaceae in the Maritime Provinces of Canada was completed under the assumption that only 2 species, Saccharina latissima (including S. longicruris; simple blade) and Laminaria digitata (digitate blade), were present in the flora. However, the species S. nigripes, which can look morphologically similar to S. latissima and L. digitata, was recently recorded. We used molecular tools to observe how Laminariaceae community composition varied across fetch distances and years and to determine the relative abundance of S. nigripes in the Bay of Fundy intertidal zone. Over 2 years (2010 and 2011) we studied Laminariaceae across a fetch gradient (sheltered to wave-exposed) in 3 regions (Lepreau, Campobello and Grand Manan), with an additional 3 years (2012 to 2014) of data collected from the Lepreau region. Sheltered sites were most similar to each other and were composed of 99% S. latissima. S. nigripes was rare in its simple-bladed morphology, as well as at sheltered sites, and likely does not affect previous literature on S. latissima. Conversely, S. nigripes was the dominant digitate kelp in 2010 and 2011 at moderate and wave-exposed sites; however, it was rare from 2012 to 2014, which may be correlated with increased water temperature. Previous studies on the ecology and distribution of L. digitata in this region may have included S. nigripes in their observations; therefore, further studies on the Laminariaceae in Atlantic Canada must be performed to determine whether the ecology of L. digitata and S. nigripes differ, as S. nigripes is the dominant digitate kelp in certain years.

KEY WORDS: Community structure · Intertidal · Kelp · Laminariaceae · Molecular identity · Saccharina nigripes · Wave exposure