Arctic marine phytobenthos of northern Baffin Island

Abstract

Global climate change is expected to alter the polar bioregions faster than any other marine environment. This study assesses the biodiversity of seaweeds and associated eukaryotic pathogens of an established study site in northern Baffin Island (72° N), providing a baseline inventory for future work assessing impacts of the currently ongoing changes in the Arctic marine environment. A total of 33 Phaeophyceae, 24 Rhodophyceae, 2 Chlorophyceae, 12 Ulvophyceae, 1 Trebouxiophyceae, and 1 Dinophyceae are reported, based on collections of an expedition to the area in 2009, complemented by unpublished records of Robert T. Wilce and the first-ever photographic documentation of the phytobenthos of the American Arctic. Molecular barcoding of isolates raised from incubated substratum samples revealed the presence of 20 species of brown seaweeds, including gametophytes of kelp and of a previously unsequenced Desmarestia closely related to D. viridis, two species of Pylaiella, the kelp endophyte Laminariocolax aecidioides and 11 previously unsequenced species of the Ectocarpales, highlighting the necessity to include molecular techniques for fully unraveling cryptic algal diversity. This study also includes the first records of Eurychasma dicksonii, a eukaryotic pathogen affecting seaweeds, from the American Arctic. Overall, this study provides both the most accurate inventory of seaweed diversity of the northern Baffin Island region to date and can be used as an important basis to understand diversity changes with climate change.

Keywords: COI; Desmarestia; Phaeophyceae; Pylaiella; cox3; germling emergence; macroalgae; molecular barcoding.

Figure 1

Study area: (1) Cape Hatt, (2) the outer side of Bay 11/12, (3) the south of Ragged Island, (4) Bay 11/12, (5) Z lagoon.

Figure 2

In situ photographs of the phytobenthos of northern Baffin Island at exposed locations, taken during the 2009 expedition to northern Baffin Island. (A) Barren rocks, ~1 m below low water – only Pylaiella as a summer annual is visible in crevices. (B) Epilithic Pylaiella, ~2 m deep. (C) Halosiphon tomentosus, a typical representative of the upper sublittoral at ~3 m depth. (D) Fucus evanescens in the sublittoral at ~3 m depth. (E) Rocks at ~3 m depth, demonstrating the effects of ice scouring – the upper side of the rocks, which would harbor rich macroalgal vegetation anywhere else in the world outside the polar regions, is free of vegetation cover. (F) Dense canopy of the kelps Saccharina latissima, S. longicruris, Laminaria solidungula and Alaria esculenta at ~7 m depth. (G) Agarum clathratum is typical of the lower sublittoral vegetation at ~10–15 m depth. (H) Once the kelp forest becomes patchy and ultimately disappears at ~15 m depth, coralline red algae dominate hard substrata.

Figure 3

Underwater images of Platysiphon glacialis, taken off Cape Hatt in the Ragged Channel area of northern Baffin Island. Platysiphon can attach to a remarkable diversity of substrata, including rock, sea shells, coralline algae, marine snails, and sponges (A–F). The perennial form (previously denominated Punctaria glacialis, G and H) lives often detached and is commonly found on the back of sea urchins. (H) It shows a typical habitat of Platysiphon at ~10 m depth. Platysiphon is frequently found together with Halosiphon tomentosus (C–H).

Figure 4

Fjordic environments with low currents are characterized by masses of dead macrophyte biomass, covered by a layer of live filamentous algae and, occasionally, Platysiphon glacialis, Fucus evanescens, Saccharina latissima, S. longicruris, Laminaria solidungula, and Desmarestia aculeata. Typically, everything is covered with large amounts of fine sediment.

Figure 5

Neighbor‐Joining phylogram displaying 5′‐COI clustering of 63 brown algal sequences, including 37 public references and sequences of 26 clonal cultures raised from environmental samples collected at Baffin Island (taxon names starting with BI). The eight major clusters obtained, in part corresponding to known higher taxa, are numbered consecutively 1–8 to the right of the tree, their roots are indicated by dark circles. 1. Desmarestiales, 2. Laminariales, 3. Scytosiphonaceae, 4. Ectocarpaceae, 5. Chordariaceae, 6. Hincksia cluster, 7. Acinetospora cluster, 8. Pylaiella cluster. Clusters 6–8 are traditionally classified together in Acinetosporaceae, however, they did not form a single clade in our analyses.

Figure 6

Neighbor‐Joining phylogram displaying 3′‐COI clustering of 35 brown algal sequences, including 19 public references and sequences of 16 clonal cultures raised from environmental samples collected at Baffin Island (taxon names starting with BI). The major clusters obtained are provided as numbers, corresponding to the clusters in Figure 5. Cluster 7 is absent because of unavailable reference sequences.

Figure 7

Neighbor‐Joining phylogram displaying cox3 clustering of 42 brown algal sequences, including 17 public references and sequences of 25 clonal cultures raised from environmental samples collected at Baffin Island (designations starting with BI). The major clusters obtained are provided as numbers, corresponding to the clusters in Figure 5. Cluster 7 is absent because of unavailable reference sequences.

Figure 8

Micrographs of permanent mounts prepared from cultured isolates from substratum samples. (A) Gametophyte of Saccharina latissima (BI063); (B) gametophyte of Desmarestia aculeata (BI061); (C) gametophyte of a hitherto unsequenced, possibly novel Desmarestia sp. (BI064); (D–F) 3 examples of previously unsequenced, filamentous brown algae (D: BI0033, E: BI048, F: BI030).