Macrobenthos of the nearshore Aleutian Archipelago, with emphasis on invertebrates associated with Clathromorphum nereostratum (Rhodophyta, Corallinaceae)

Abstract

In the Aleutian Islands, Alaska, crustose coralline algae can be widespread in the low intertidal and shallow subtidal regions, and cover most available hard substrates. The longevity and slow growth-rate of coralline algae make them vulnerable to major disturbances, including anthropogenic disturbances and ocean acidification. Subtidal habitats dominated by crustose coralline algae are often associated with sea urchin-barren grounds and regarded as supporting limited invertebrate communities, especially compared with the adjacent kelp forests. Clathromorphum nereostratum is one of the most abundant crustose coralline algae found in the Aleutian Islands. Although the surface of this crustose alga exhibits little structural complexity, it can develop into crusts half-a-meter thick (2-10 cm in this study) that provide microhabitats for a variety of cryptic invertebrates. Despite the omnipresence of this alga throughout the nearshore Aleutians, very little is known about its associated faunal community. In the summers of 2006 and 2007, a benthic survey was conducted at 50 sites throughout the shallow (<20 m), nearshore Aleutian Islands as part of the Alaska Monitoring and Assessment Program.The habitat encountered at each site was categorized as soft sediment, macroalgae-dominated, or crustose corallinedominated. At each site, scuba divers sampled three 0.06-m 2 quadrats. Invertebrate communities associated with thick crustose coralline algae were compared with soft-sediment and macroalgae-dominated communities based on faunal abundance and diversity. Despite the depauperate appearance of crustose habitats, this study revealed that crustose environments support faunal communities as diverse and abundant as those found in rich macroalgal habitats.

The Coralline Genus Clathromorphum Foslie emend. Adey: Biological, Physiological, and Ecological Factors Controlling Carbonate Production in an Arctic-Subarctic Climate Archive

“…The coralline provides a surface for algal epiphytes, and both the corallines and the epiphytes are grazed by many invertebrates. They are also very important producers of secondary biomass, mostly by providing a porous, reef-like habitat to innumerable invertebrates that utilize mostly planktonic sources of primary production (Chenelot et al, 2011). Additionally, they provide significant ecosystem support for Subarctic-Arctic fisheries that are now expanding in importance.…”

“…In both the Atlantic and the Pacific, these carbonateencrusted bottoms have been widely referred to as "coralline, sea urchin barrens" (Mathieson et al, 1991;Estes and Duggins, 1995;Steneck et al, 2002); however, this description is certainly a misnomer, as they may well be among the richer shallow marine bottoms of the marine Holarctic (Himmelman, 1991;Chenelot et al, 2011). The Chenelot et al (2011) study focused on abundant invertebrates resident in Clathromorphum nereostratum in the Aleutian Islands, but it is likely that a similar relationship exists for cor-stromes in the northwestern North Atlantic.…”

“…The Chenelot et al (2011) study focused on abundant invertebrates resident in Clathromorphum nereostratum in the Aleutian Islands, but it is likely that a similar relationship exists for cor-stromes in the northwestern North Atlantic. Drying fragments of cor-strome on research vessel laboratory benches generally release large quantities of invertebrates, especially grazing chitons and filter-feeding brittle stars.…”

Editorial: Arctic marine biodiversity under change

“…Chenelot et al (2011) sampled at 50 sites (2006)(2007) from the Eastern to Western Aleutians Islands, Alaska, as part of the Alaska Monitoring and Assessment Program. Abundant, thick crustose coralline algae (Clathromorphum nereostratum) found at these sites provided microhabitats for 707 invertebrate taxa, many of which were cryptic within the 2-10 cm thick matrix of corallines.…”

Saccate thallus of the red alga Halosaccion glandiforme harbor diverse invertebrate fauna

“…Numerous invertebrates are dependent on seaweeds with varying morphological features, including the complex three-dimensional Macrocystis (Graham 2004), the compact spongy Codium (Trowbridge 1998;Bulleri et al 2006), the fan-like broad thallus of Chondrus (Janiak and Whitlatch 2012), the crustose coralline algae Clathromorphum (Chenelot et al 2011) and the calcareous rhodoliths (Foster 2001). Steller et al (2003) reported that the total number of organisms supported by the coralline red algal rhodoliths significantly increased with both complexity (branching density) and space available (thallus volume) when compared with adjacent sand community.…”