title: Large-scale spatial distribution patterns of echinoderms in nearshore rocky habitats.
abstract: This study examined echinoderm assemblages from nearshore rocky habitats for large-scale distribution patterns with specific emphasis on identifying latitudinal trends and large regional hotspots. Echinoderms were sampled from 76 globally-distributed sites within 12 ecoregions, following the standardized sampling protocol of the Census of Marine Life NaGISA project (www.nagisa.coml.org). Sample-based species richness was overall low (<1-5 species per site), with a total of 32 asteroid, 18 echinoid, 21 ophiuroid, and 15 holothuroid species. Abundance and species richness in intertidal assemblages sampled with visual methods (organisms >2 cm in 1 m(2) quadrats) was highest in the Caribbean ecoregions and echinoids dominated these assemblages with an average of 5 ind m(-2). In contrast, intertidal echinoderm assemblages collected from clearings of 0.0625 m(2) quadrats had the highest abundance and richness in the Northeast Pacific ecoregions where asteroids and holothurians dominated with an average of 14 ind 0.0625 m(-2). Distinct latitudinal trends existed for abundance and richness in intertidal assemblages with declines from peaks at high northern latitudes. No latitudinal trends were found for subtidal echinoderm assemblages with either sampling technique. Latitudinal gradients appear to be superseded by regional diversity hotspots. In these hotspots echinoderm assemblages may be driven by local and regional processes, such as overall productivity and evolutionary history. We also tested a set of 14 environmental variables (six natural and eight anthropogenic) as potential drivers of echinoderm assemblages by ecoregions. The natural variables of salinity, sea-surface temperature, chlorophyll a, and primary productivity were strongly correlated with echinoderm assemblages; the anthropogenic variables of inorganic pollution and nutrient contamination also contributed to correlations. Our results indicate that nearshore echinoderm assemblages appear to be shaped by a network of environmental and ecological processes, and by the differing responses of various echinoderm taxa, making generalizations about the patterns of nearshore rocky habitat echinoderm assemblages difficult.
authors.affiliation: School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, Alaska, United States of America. iken@ims.uaf.edu
authors.forename: Katrin
authors.initials: K
authors.lastname: Iken
authors.forename: Brenda
authors.initials: B
authors.lastname: Konar
authors.forename: Lisandro
authors.initials: L
authors.lastname: Benedetti-Cecchi
authors.forename: Juan José
authors.initials: JJ
authors.lastname: Cruz-Motta
authors.forename: Ann
authors.initials: A
authors.lastname: Knowlton
authors.forename: Gerhard
authors.initials: G
authors.lastname: Pohle
authors.forename: Angela
authors.initials: A
authors.lastname: Mead
authors.forename: Patricia
authors.initials: P
authors.lastname: Miloslavich
authors.forename: Melisa
authors.initials: M
authors.lastname: Wong
authors.forename: Thomas
authors.initials: T
authors.lastname: Trott
authors.forename: Nova
authors.initials: N
authors.lastname: Mieszkowska
authors.forename: Rafael
authors.initials: R
authors.lastname: Riosmena-Rodriguez
authors.forename: Laura
authors.initials: L
authors.lastname: Airoldi
authors.forename: Edward
authors.initials: E
authors.lastname: Kimani
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Shirayama
authors.forename: Simonetta
authors.initials: S
authors.lastname: Fraschetti
authors.forename: Manuel
authors.initials: M
authors.lastname: Ortiz-Touzet
authors.forename: Angelica
authors.initials: A
authors.lastname: Silva
mesh_terms: D000531:Altitude; D000818:Animals; D000864:Antarctic Regions; D001267:Atlantic Ocean; D044822:Biodiversity; D017691:Caribbean Region; D004447:Echinodermata / Q000145:classification / Q000254:growth & development*; D017753:Ecosystem; D004777:Environment; D005843:Geography; D009792:Oceans and Seas; D010140:Pacific Ocean; D011157:Population Dynamics; D013045:Species Specificity